Investigating the Potential of Biodiesel Production In...
Transcript of Investigating the Potential of Biodiesel Production In...
Investigating the Potential of Biodiesel Production in Fiji:
Facilitating Sustainable Production in the Fiji Region
By
Radhika SINGH (BSc, PG Dip. Chem.)
A Thesis Submitted in Partial Fulfillment of the Requirements for the degree of
Master of Science in Chemistry
School of Biological and Chemical Sciences, Faculty of Science, Technology and Environment,
The University of the South Pacific.
November, 2008
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DECLARATION
I hereby declare that the work contained in this thesis is my very own and where I have used the thoughts and works of others I have clearly indicated this. Researcher:
Radhika Singh S01006753
We hereby confirm that the work contained in this thesis is the work of Radhika Singh unless otherwise stated. Principle supervisor: ____________________
Dr. Vincent. W. Bowry University of the South Pacific
Co-Supervisor 1: ____________________
Professor Subramanium Sotheeswaran University of the South Pacific
Co-Supervisor 2: ____________________
Associate Professor Sadaquat Ali University of the South Pacific
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DEDICATION
I would like to dedicate this thesis to my parents
Surendra Singh and Arun Kumari
for their invaluable love and support.
Thanks.
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ACKNOWLEDGEMENTS
This research has been exciting and sometimes challenging, but always an interesting
experience. It has been made possible through the support and encouragement of many
other people.
I would like to thank my research supervisors: Dr. Vincent Bowry, principle
supervisor, for his encouragement, guidance and correction of the manuscript; co-
supervisors, Professor Subramanium Sotheeswaran and Associate Professor
Sadaquat Ali, for their input and providing financial assistance from the Natural
Products funds.
This project was undertaken as part of the Biofuel Research awarded by jointly funded
SOPAC- USP Graduate Assistant Scholarship. I would like to thank Mr. Paul
Fairbain, the Manger of Community Lifelines Programme, SOPAC for providing me
the opportunity to be a part of his team. Also, thanks to Mr. Jan Cloin, Energy Advisor,
for the fruitful discussions on the local biofuel perspective and the staff of Community
Lifeline Programme – Energy Sector, for their cooperation and assistance in
literature search.
I am thankful to Associate Professor Roger Read for his guidance at the School of
Chemistry, University of New South Wales in the duration of my collaborative studies
there. I am indebted to Dr. Joseph Brophy, Honorary Fellow, for his kindness and
assistance in analysis of the research samples in Gas Chromatography/ Mass
Spectrometry.
I would like to gratefully acknowledge the assistance and cooperation of the chemistry
division technical staff at the University of the South Pacific. Mr. Steve Sutcliffe, Lab
Manager, for his efforts in organising the chemicals and accessories required in this
research and Mr. Sachin Singh, Scientific Officer, for providing training on
instrumentation and professional assistance. I would also like to thank Dr. Culwick
Togamana for his support.
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I wish to thank the Managers of franchise companies for providing valuable samples,
whose names cannot be disclosed as part of the agreement to take part in this research.
I would like to acknowledge my loving husband Mr . Sachin Singh, for his guidance
and support.
Finally, thanks to my sister, Mrs. Sarika Dayal and my brothers, Mr. Sachindra
Singh, Mr. Ram Aman Singh and Mr Rajeev Singh. It is always a privilege to be in
their company.
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ABSTRACT
Biodiesel an alternative renewable energy resource produced from alcohol and
vegetable oil. Its production and quality control has been explored extensively using the
available local raw materials. The final Biodiesel fuel produced has been characterised
by examining it physical and chemical properties.
Coconut oil was found to be the most suitable vegetable oil raw material having iodine
value of 7.9, free fatty acid content of 3.72%, less than 1% moisture content and non
detectable phosphorus content. These chemical analyses were carried out by
standardised AOCS methods. Other lipid sources investigated included used vegetable
oil (sourced from various franchise companies locally), canola oil and soybean oil.
Ethanol has the potential to be produced locally and thus was deemed as an alcohol
source. Methanol was also investigated. The catalysts investigated were sodium and
potassium hydroxide.
The synthetic methods investigated were designed to suit the FFA content of the lipid
raw materials used. These include Acid pretreatment, one step base catalyzed
transesterification (Method 1), One step base transesterification (Method 2A), Two step
base transesterifcation (Method 2B) and Base neutralization, one step base
transesterification (Method 3). Simple gravitation separation of glycerol layer was an
effective method of glycerol removal. This was confirmed by FTIR spectrometry
technique. Saline water washing was found to be most effective in removing
saponification products from the crude biodiesel mixture.
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The quality of the Biodiesel fuel produced using these methods were determined by
chemical and physical analysis. Gas chromatography (FID and MS) and Gel
Permeation Chromatography were employed to identify and quantify the alkyl ester and
total and bound glyceride content. These two methods were found to be a
complementary as far as the production and quality control of the final product is
concerned. Viscosities of the esters were also measured.
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TABLE OF CONTENT
DECLARATION ....................................ERROR! BOOKMARK NOT DEFINED.
DEDICATION.........................................................................................................III
ACKNOWLEDGEMENTS..................................................................................... IV
ABSTRACT............................................................................................................ VI
TABLE OF CONTENT ........................................................................................VIII
ACRONYMS AND DEFINITION.......................................................................... XI
LIST OF FIGURES...............................................................................................XIII
LIST OF TABLES .................................................................................................XV
1 CHAPTER 1: GENERAL OVERVIEW .................................................... 1
1.1 INTRODUCTION ...................................................................................... 1
1.2 AIMS ......................................................................................................6
2 CHAPTER 2: LITERATURE REVIEW AND BACKGROUND ........ ..... 7
2.1 HISTORY ................................................................................................ 7
2.2 GLOBAL PERSPECTIVE AND BIODIESEL STANDARDS ............................. 9
2.3 REGIONAL PERSPECTIVE AND PRODUCTION ....................................... 12
2.4 ENVIRONMENTAL BENEFITS OF BIODIESEL ......................................... 16
3 CHAPTER 3 – RAW MATERIALS – FEEDSTCK AVAILABLITY AN D
ANALYSIS................................................................................................. 21
3.1 INTRODUCTION .................................................................................... 21
3.2 IDENTIFYING & SURVEYING EDIBLE OIL FEEDSTOCKS. ..................... 23
3.2.1 Lipid source material........................................................................ 23
3.2.2 Alcohol as raw material.................................................................... 28
3.3 METHODOLOGY : ANALYSIS OF RAW M ATERIALS ............................... 32
3.3.1 Sampling methods............................................................................ 33
3.3.2 Chemical Analysis ........................................................................... 34
3.3.2.1 Free Fatty Acid (FFA) .............................................................. 34
3.3.2.2 Iodine Value (Wijs’ Method).................................................... 37
3.3.2.3 Phosphorus Analysis................................................................. 39
3.3.3 Physical Properties ........................................................................... 42
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3.3.3.1 Moisture and Volatile Matter.................................................... 42
3.4 RESULTS AND DISCUSSION ................................................................... 44
3.4.1 Chemical Analysis of Raw Materials................................................ 44
3.4.1.1 Free Fatty Acid Content............................................................ 44
3.4.1.2 Iodine Value............................................................................. 45
3.4.1.3 Phosphorous content................................................................. 46
3.4.2 Physical Analysis of Raw Materials ................................................. 48
3.4.2.1 Moisture content....................................................................... 48
3.4.3 Raw Material Used in this Research: Logistics Study ....................... 49
3.4.3.1 Lipid Raw Material................................................................... 50
4 CHAPTER 4 SYNTHESIS AND PURIFICATION................................. 52
4.1 INTRODUCTION .................................................................................... 52
4.2 METHODOLOGY .................................................................................. 58
4.2.1 Synthesis Process ............................................................................. 58
4.2.1.1 Method 1 Acid pretreatment, one-step base-catalysed
transesterification .................................................................... 60
4.2.1.2 Method 2A - One Step Base Transesterification (No pretreatment)
................................................................................................ 66
4.2.1.3 Method 2B – Two-Step Base Transesterification (No pretreatment)
................................................................................................ 70
4.2.1.4 Method 3 Base Neutralisation, One Step Base Transesterification71
4.3 RESULTS AND DISCUSSION................................................................... 75
4.3.1 Method Optimization ....................................................................... 75
4.3.2 Observations and results for the methodology used to prepare biodiesel
......................................................................................................... 79
4.3.3 Observations and results for purification process.............................. 83
4.3.3.1 Washing Method optimization.................................................. 83
4.3.3.2 Comparison of washing processes using distilled water and saline
water ....................................................................................... 85
5 CHAPTER 5 CHEMICAL AND PHYSICAL ANALYSIS OF BIODIES EL
.................................................................................................................... 89
5.1 INTRODUCTION .................................................................................... 89
5.2 METHYL AND ETHYL ESTERS (BIODIESEL ) .......................................... 95
5.2.1 Gas Chromatography – Flame Ionisation Detector (FID).................. 95
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5.2.1.1 Methodology ............................................................................ 95
5.2.1.2 Results...................................................................................... 98
5.2.1.3 Discussion .............................................................................. 101
5.2.2 Gel Permeation Chromatography.....................................................107
5.2.2.1 Methodology101 ...................................................................... 107
5.2.2.2 Results.................................................................................... 112
5.2.2.3 Discussion .............................................................................. 116
5.3 MONO-, DI- AND TRIGLYCERIDES (FREE AND TOTAL GLYCERIDES ) ....120
5.3.1 Gas Chromatography.......................................................................120
5.3.1.1 Methodology102 ...................................................................... 120
5.3.1.2 Results and Dicussion............................................................. 123
5.3.2 Gel Permeation Chromatography.....................................................124
5.3.2.1 Methodology .......................................................................... 124
5.3.2.2 Results.................................................................................... 129
5.3.2.3 Discussion .............................................................................. 133
5.3.3 Gas chromatography – Mass Spectrometry......................................139
5.3.3.1 Methodology .......................................................................... 139
5.3.3.2 Results.................................................................................... 140
5.4 PHYSICAL ANALYSIS ..........................................................................141
5.4.1 Viscocity.........................................................................................141
5.4.1.1 Methodology .......................................................................... 141
5.4.1.2 Results.................................................................................... 141
5.5 IN SUMMARY ......................................................................................142
6 CHAPTER 6 CONCLUSION AND RECOMMENDATION ............ .....145
REFERENCE.........................................................................................................151
APPENDIX............................................................................................................164
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ACRONYMS AND DEFINITION
Acronyms
ASTM American Standard Test Material
SOPAC Pacific Islands Geoscience Commission
COCOHOL Esterified Coconut Oil
SPC-CIRAD Secretariat for Pacific Commission – Agricultural Research
Centre for International Development.
PAH Polycyclic Aromatic Hydrocarbon.
NEB Net Energy Balance
GC-FID Gas Chromatography Flame Ionisation Detector
CI Compression Ignition
SI Spark Ignition
CEN European Committee of Standardisation
ROME Rapeseed Oil Methyl Ester
FAMAE Fatty Acid Monoalkyl Ester
FAME Fatty Acid Methyl Ester
VOME Vegetable Oil Methyl Ester
TG Triglyceride
DG Diglyceride
MG Monoglyceride
FFA Free Fatty Acid
AOCS American Oil Chemist Society
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Definitions
Viscosity The resistance of the fuel to flow at a given temperature.
Measured by ASTM D445 method.
Cetane Number The percentage of cetane (C16H34) in a amixture of ceatane and
methylnaphthalene that has the same ignition delay as the test
fuel, the higher the cetane number the shorter the ignition delay
(ASTM D613)
Flash Point
the temperature in which a liquid can be ignited in air (ASTM
D93).
Cloud Point
The temperature below which an oil becomes cloudy due to
crystal formation. Higher values give better performance in cold
conditions (ASTM D2500)
Pour Point
The temperature below which an oil ceases to flow under
prescribed conditions (per ASTM D97)
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LIST OF FIGURES
Figure 1.1 Transeterification of Triglycerides·····························································3
Figure 1.2 Chemical Structures of Oil, Biodiesel and Petrodiesel. ·······························4
Figure 2.1. Coconut Oil Production Potential and Exports of Pacific Island Countries19.
······················································································································ 12
Figure 2.2 Biodiesel Batch Process Plant at Lami. ···················································· 14
Figure 2.3 Some PAHs Emitted from Diesel Exhaust ··············································· 16
Figure 3.1 Lipid Classes and Some Fatty Acids and Found in Edible Oils.················· 23
Figure 3.2 Chemical and Physical Analysis of Lipid Raw Materials ·························· 32
Figure 3.3 Calibration Graph of Phosphorous Standards ··········································· 47
Figure 4.1 Transesterification of triglycerides - Three-step consecutive reactions······· 52
Figure 4.2 Mechanism of Acid Catalysed Transesterification of Lipids.····················· 54
Figure 4.3 Mechanism of Base Catalysed Transesterification of Lipids87··················· 55
Figure 4.4 Soap formation due to high FFA and deactivation of catalyst during Base
catalysed transesterification process ·································································56
Figure 4.5 Successful ester (biodiesel) synthetic methodologies. ······························· 58
Figure 4.6 Fate of Lipid Feedstock Depending of their Free Fatty Acid Content.········ 59
Figure 4.7 Flowchart Illustrating Procedure for Method 1········································· 60
Figure 4.8 Flowchart Illustrating Procedure for Synthetic Method 2A························ 67
Figure 4.9 Flowchart Illustrating Synthetic Procedure for Method 2B························ 70
Figure 4.10 Flowchart Illustrating Synthetic Procedure for Method 3························ 71
Figure 4.11 Miscibility Problems during Synthesis of Biodiesel································ 75
Figure 4.12 Treatment of Reaction Mixture to Obtain Purified Biodiesel ·················· 80
Figure 4.13 Soap formation while washing crude biodiesel (methanolysis) ··············· 81
Figure 4.14 Excess Soap Formation while Washing Crude Biodiesel (ethanolysis)····· 82
Figure 4.15 Infra Rad Spectra of Ester Before Purification Process ··························· 87
Figure 4.16 Infra Rad Spectra of Ester After Purification Process······························ 87
Figure 5.1 Intermediates formed from transesterification of trilauric acid ·················· 90
Figure 5.2 Purified Coconut Oil Methyl Ester Synthesized Using Method 2A.········· 102
Figure 5.3 Percentage of Methyl Laurate in Coconut Oil Methyl Ester (GC-FID)····· 103
Figure 5.4 Purified waste oil methyl ester synthesized using method 3 (GC-FID).···· 104
Figure 5.5 Percentage of Methyl Laurate in Coconut Oil Ethyl Ester (GC-FID) ······· 105
Figure 5.6 Purified Coconut Oil Ethyl Ester (GC-FID) showing similar profile. ······· 106
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Figure 5.7 Calibration Curve of Methyl Oleate······················································· 108
Figure 5.8 Calibration Curve of Methyl Laurate ····················································· 109
Figure 5.9 Calibration Curve of Ethyl Oleate ························································· 109
Figure 5.10 Calibration Curve of Ethyl Laurate······················································ 110
Figure 5.11 Percentage of Methyl Laurate in Coconut Oil Methyl Ester (GPC) ······· 117
Figure 5.12 Percentage of Ethyl Laurate in Coconut Oil Ethyl Ester (GPC) ············· 118
Figure 5.13 Calibration Curve of Trilauric Acid ····················································· 124
Figure 5.14 Calibration Curve of Dilauric Acid······················································ 125
Figure 5.15 Calibration Curve of Monolauric Acid················································· 126
Figure 5.16 Calibration Curve of Trioliec Acid ······················································ 126
Figure 5.17 Calibration Curve of Dioliec Acid ······················································· 127
Figure 5.18 Calibration Curve of Monoliec Acid···················································· 128
Figure 5.19 GPC chromatogram of Coconut oil Biodiesel Sample··························· 134
Figure 5.20 Percentage Concentration of Glyceride content in Coconut oil Methyl
Esters ··········································································································· 135
Figure 5.21 Percentage Concentrations of Glycerides in Coconut Oil Ethyl Esters ··· 136
Figure 5.22 Using Percentage Glyceride Content to Compare Different Synthetic
Methods. ······································································································ 137
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LIST OF TABLES
Table 2.1 Diesel Substitutes Made From or Based on Vegetable Oil 13 .........................8
Table 2.2 Fuel Properties of Biodiesel Compared to Conventional Diesel Fuel. ............9
Table 2.3 Biodiesel Fuel Standards in Europe Countries.............................................10
Table 2.4 Fuel Standards for Biodiesel in Australia 18.................................................11
Table 2.5 Coconut oil, Mixtures and Derivatives as Fuel in the Pacific. ......................13
Table 2.6 Emission Change in Biodiesel and Blended Biodiesel Fuel5. .......................18
Table 3.1 Comparisons Between Alkaline and Acidic Catalyst ...................................30
Table 3.2 Fatty Acid Composition of Commercial Oil Samples Analysed6. ................33
Table 3.3 Lipid Source Before Use from Three Different Outlets. ..............................34
Table 3.4 Specifications according to A.O.C.S Ca 5a-40 ............................................35
Table 3.5 Free Fatty Acid Values Reported as the Respective Fatty Acid ...................36
Table 3.6 Recommended Masses of Sample for Iodine Value.....................................38
Table 3.7 Preparation of Phosphorous Standards ........................................................41
Table 3.8 Free Fatty Acid Content of Commercial Oil for Biodiesel Synthesis ...........44
Table 3.9 Free Fatty Acid Content of Waste Oil for Biodiesel Synthesis.....................44
Table 3.10 Iodine values of commercial oil samples ...................................................46
Table 3.11 Iodine values of waste oil samples ............................................................46
Table 3.12 Phosphorous content of commercial oil samples .......................................47
Table 3.13 Moisture Content and Volatile Matter of Commercial Oil Samples ...........48
Table 3.14 Moisture Content and Volatile Matter of Waste Oil Samples.....................48
Table 4.1 Treatment of lipid raw materials undertaken prior to transesterification
reactions to produce biodiesel.............................................................................59
Table 4.2 Molecular weights of Triglycerides in Lipid Raw Material..........................66
Table 4.3 Trial for suitable catalyst for transesterification reaction and its observation76
Table 4.4 Optimizing Pretreatment Coconut Oil Using Acid Catalyst and Methanol...77
Table 4.5 Optimizing Pretreatment Process of Coconut Oil using Acid Catalyst and
Ethanol. ..............................................................................................................78
Table 4.6 Percentage Loss of water soluble during purification of biodiesel synthesized
using the methods investigated. ..........................................................................84
Table 4.7 Purification of Coconut Oil Ethyl Esters with Distilled and Saline Wash
Water..................................................................................................................86
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Table 5.1 Some Common Fatty Acids and There Esters..............................................89
Table 5.2 Property Data for Methyl Ester Biodiesel Fuels 91.......................................91
Table 5.3. Summary of Some Parameters for Analysing Biodiesel in Gas
Chromatography. ................................................................................................92
Table 5.4. Summary of Some Parameters for Analysing Biodiesel by High Performance
Liquid Chromatography97. ..................................................................................93
Table 5.5 Gas Chromatography FID Instrumentation Condition for Biodiesel Analysis
...........................................................................................................................96
Table 5.6 Calculation of the Percentage Methyl Ester in the Samples (GC-FID).........98
Table 5.7 Calculation of the Percentage Ethyl Ester in the Samples (GC- FID)...........99
Table 5.8 Calculation of the Percentage Methyl Ester in the Samples (GC-FID)....... 100
Table 5.9 Calculation of the Percentage Ethyl Ester in the Samples (GC-FID).......... 100
Table 5.10 Percentage Concentration of Methyl Esters Analysed by GC FID ........... 103
Table 5.11 Percentage Concentration of Ethyl Esters Analysed by GC-FID.............. 104
Table 5.12 Peak Area versus Concentration of Methyl Oleate................................... 108
Table 5.13 Peak Area versus Concentration of Methyl Laurate................................. 108
Table 5.14 Peak Area versus Concentration of Ethyl Oleate ..................................... 109
Table 5.15 Peak Area versus Concentration of Ethyl Laurate.................................... 110
Table 5.16 Gel Permeation Chromatography instrumentation conditions for Biodiesel
analysis............................................................................................................. 111
Table 5.17 Concentration of Methyl Oleate in Waste Oil Biodiesel Samples (GPC) . 112
Table 5.18 Concentratrion of Methyl Laurate in Coconut Oil Biodiesel Samples (GPC)
......................................................................................................................... 113
Table 5.19 Concentration of Ethyl Oleate in Waste Oil Biodiesel Samples (GPC) .... 114
Table 5.20 Concentratrion of Ethyl Laurate in Coconut Oil Biodiesel Samples (GPC)
......................................................................................................................... 115
Table 5.21 Percentage Concentration of Methyl Esters Analysed by GPC ................ 116
Table 5.22 Percentage Concentration of Ethyl Esters Analysed by GPC ................... 118
Table 5.23 Glycerides Calibration solutions for contaminants in biodiesel from waste
oil (GC-FID)..................................................................................................... 121
Table 5.24 Gas Chromatography (FID) Instrumentation Condition for Biodiesel
Contaminants Analysis ..................................................................................... 122
Table 5.25 Peak Area versus Concentration of Trilauric Acid................................... 125
Table 5.26 Peak Area versus Concentration of Dilauric Acid.................................... 125
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Table 5.27 Peak Area versus Concentration of Monolauric Acid .............................. 126
Table 5.28 Peak Area versus Concentration of Trioliec Acid .................................... 127
Table 5.29 Peak Area versus Concentration of Dioliec Acid..................................... 127
Table 5.30 Peak Area versus Concentration of Monoliec Acid ................................. 128
Table 5.31 Concentration of Bound Glycerides in Waste Oil Biodiesel Samples....... 129
Table 5.32 Concentration of Bound Glycerides in Coconut Oil Biodiesel Samples ... 130
Table 5.33 Concentration of Bound Glycerides in Waste Oil Biodiesel Samples....... 131
Table 5.34 Concentration of Bound Glycerides in Coconut Oil Biodiesel Samples ... 132
Table 5.35 Molecular weights of components in biodiesel samples analysed ............ 133
Table 5.36 Relative Response Factors of Glycerides to Esters. ................................. 135
Table 5.38 Mass Spectral Data of Fatty Acid Esters Analysed. ................................. 140
Table 5.39 Viscosity of biodiesel samples investigated............................................. 141
Table 5.40 Advantages and Disadvantages of Analysing Biodiesel using GC ........... 143
Table 5.41 Advantages and Disadvantages of Analysing Biodiesel using GPC ......... 144
Table A.15 Pretreatment of Coconut oil - METHANOLYSIS................................... 178
Table A.16 FFA of Pretreated Coconut Oil............................................................... 178
Table A.17 Transesterification of Pretreated Coconut Oil ......................................... 179
Table A.18 Pretreatment of Waste oil – METHANOLYSIS..................................... 179
Table A.19 Transesterification of Pretreated Oil ....................................................... 180
Table A.20 Coconut oil - METHANOLYSIS ........................................................... 181
Table A.22 Soybean oil - METHANOLYSIS ........................................................... 182
Table A.23 Soybean oil – ETHANOLYSIS.............................................................. 182
Table A.24 Canola oil – METHANOLYSIS............................................................. 182
Table A.25 Canola oil – ETHANOLYSIS ................................................................ 183
Table A.26 Transesterification of Waste Oil - ETHANOLYSIS ............................... 183
Table A.27 Transesterification of Coconut Oil - ETHANOLYSIS............................ 184
Chapter1: General Overview
1
1 CHAPTER 1: GENERAL OVERVIEW
1.1 INTRODUCTION
Depletion of the world’s fossil fuels and the high global demand in energy has led to a
relentless increase in fuel prices. Higher fuel prices have led to higher transport and
power costs, which, to make matters worse, have a multiplied effect on the prices of
goods and services. One way of offsetting this trend is to replace fossil fuel – in
dwindling supply and at the mercy of global politics – with renewable energy sources
such as wind, tidal and solar energy, and with biofuels. The replacement of fossil fuels
with renewable sources such as biofuel also benefits the environment since it helps to
reduce noxious emissions and the global warming effect of man-made CO2 emissions.
Security of fuel supply, fuel costs and the effect of fossil fuels on the environment have
become key issues that have spurred countries like Europe, Brazil and United States of
America to invest heavily in biofuel technologies. The United Nations (UN) has been
involved with supporting its member countries to move towards sustainable energy and
to develop it in their regions. The UN monitors the trends of energy production,
distribution and consumption and devises energy strategies, policies and programmes1.
For geographically isolated areas, such as the island nations of the South Pacific, the cost
and logistics of supplying petro-diesel are even more of a burden than in developed
nations. Producing biofuel in Fiji and the regions would improve the security of energy
supply and lead to the positive employment and social benefits of having a domestic
source of energy. Local production of biofuel would stimulate domestic economic growth
Chapter1: General Overview
2
and reduce the flow of capital offshore by relieving dependence on imported fossil fuel.
In 2006 the Pacific Islands Forum and Secretariat, which monitors Pacific fuel prices,
reported that the prices for kerosene and diesel were at historically high levels for the
early four month period of 20062. Since then the situation has worsened with highest-ever
crude-oil costs driving at-the-pump diesel and petrol prices up by 50% and more on 2007
levels.
Many countries in the South Pacific region have already resorted to biofuel technology to
solve this problem. Countries like Vanuatu, Marshall Islands, Samoa, Solomon Islands,
Papua New Guinea, Kiribati and Fiji, in the South Pacific have all been involved in
projects to assess the biomass of local raw materials in their countries in order to evaluate
the potential of local liquid biofuel production3. Vanuatu, the Solomons and Samoa have
replaced significant amounts of the diesel and kerosene used in generators, heaters and
lamps with local coconut oil. So far, this has only involved the edible oils themselves and
not chemically modified derivatives of the oils.
This research project explores the possibilities of a sustainable, alternative energy
resource for Fiji and the region. It focuses on the chemically modified (alcoholized)
product of vegetable oil commonly known as biodiesel as an alternative to diesel fuel.
The research examines chemical aspects of the process (as tested on various lab scales)
when it is applied to relevant oils such as coconut and available waste (used) oils. The
project has been aided in both investigation and application stages by SOPAC and by
Chapter1: General Overview
3
private enterprise with a view to supporting the production and quality control of
biodiesel in Fiji.
What is biodiesel ?
According to the specification for biodiesel (B100) American Standard Test Material
ASTM D6751-07a, biodiesel is defined as the
“monoalkyl esters of long chain fatty acids derived from renewable feedstock
such as vegetable oil or animal fat for use in compression ignition engines”4.
Bio-diesel is usually made by treating a fat or oil (trigyceride) with methyl or ethyl
alcohol and a small amount of a strong base such as sodium or potassium hydroxide as a
catalyst. Thus, e.g., coconut oil (consisting mainly of glyceryl trilaurate) when treated
with methanol (MeOH) containing a small amount of sodium hydroxide gives glycerol
(which separates as a byproduct) and coconut biodiesel (consisting mainly of methyl
laurate), as shown below (figure 1.0).
Figure 1.1 Transeterification of Triglycerides
CH2
CH
CH2
C11H22CO2
C11H22CO2
C11H22CO2
+ 3 x MeOH
CH2
CH
CH2
HO
HO
HO
base or acidcatalyst
+ 3 x C11H22CO2Me
glyceroltriglyceride
"biodiesel"(coconut methyl ester in
this example)
Chapter1: General Overview
4
The resulting long-chain fatty-acid esters, unlike the thicker parent oil, can safely be used
in unmodified diesel engines. The molecular structure of biodiesel is quite similar to
petrodiesel, see below.
Figure 1.2 Chemical Structures of Oil, Biodiesel and Petrodiesel.
The key difference between petrodiesel and biodiesel is replacement of a short segment
of the non-polar hydrocarbon chain by a polar carboxyl (CO2) group (figure1.1).
Accordingly, biodiesel made from various edible oils have similar viscosities to
petrodiesel5 and “engine performance of neat biodiesels and their blends was similar to
that of No. 2 diesel fuel with the same thermal efficiency, but higher fuel consumption.”6.
In comparison with unmodified vegetable oil, biodiesel eliminates the problems of engine
choking, deposit formation and ring sticking.
H3C
H2C
CH2
H2C
CH2
H2C
CH2
H2C
CH2
H2C
CH2
H2C
CH2
H2C
CH2
CH3
petrodiesel (represented by cetane, C16H34)
CCH2
H2C
CH2
H2C
CH2
H2C
CH2
H2C
CH2
H2C
H3C
O
OC
coconut biodiesel (represented by methyl laurate)
OH2C
CHO
H2C O
C CH2
H2C CH2
H2C CH2
H2C CH2
H2C CH2
H2C CH3
CH2C
CH2H2C
CH2H2C
CH2H2C
CH2H2C
CH2H3C
C CH2
H2C CH2
H2C CH2
H2C CH2
H2C CH2
H2C CH3
coconut oil (represented by trilauryl glycerol)
O
O
O
Chapter1: General Overview
5
Biodiesel has technical, practical and environmental advantages over petrodiesel. Thus,
it has a higher lubricity value, leading to less engine wear7. Compared to petro-diesel,
bio-diesel offers: a) a higher cetane rating8; b) a higher flashpoint (making it safer to
handle); c) lower toxicity to plants and animals9; and d) reduced exhaust emissions10.
Biodiesel is also: e) simple to phase in and out of use; f) a local renewable source of
energy; and g) highly biodegradable. Biodiesel also improves the quality of the
environment with a pleasant fruity odour and with less (and far less toxic) soot generated
in the exhaust of vehicles using it. Biodiesel has marine application10 and can also be
used in domestic and commercial boilers11. The most significant downsides of biodiesel
for use in vehicles are a greater affinity for water (due to the polar CO2 group), a greater
tendency to grow micro-organisms, and to go cloudy or set solid at low ambient
temperatures (i.e. at less than ca. 10 °C). Though the latter is clearly more of an issue in
temperate climates than in the tropical South Pacific.
Blends of biodiesel and petrodiesel have been adopted to help lower ‘greenhouse
emissions’5,12. Blended fuel is denoted as BXX, where XX denotes the percentage of
biodiesel by vol%; e.g. B20 indicates a blend of 20% of biodiesel and 80% of petro-diesel
by volume. The most popular biodiesel blend used in the United States is B20 which was
accepted by Congress in 1998 as an Environmental Pollution Act for the USA5.
Chapter1: General Overview
6
1.2 AIMS
The goals for this project were:
i. A literature study on bio-diesel production technologies, standards and
measurements (Chapter 2);
ii. To identify potential vegetable oil raw materials by assessing availability in
Fiji (Chapter 3) and suitability for producing quality bio-diesel in a local
context by examining their physical and chemical properties;
iii. To produce bio-diesel through transesterification by using the most suitable
oil available in Fiji (Chapter 4);
iv. A detailed examination of the chemical and physical properties of the bio-
diesel produced (Chapter 5); and
v. To document procedures to produce bio-diesel with the available equipment.
Chapter 2: Literature Review and Background
7
2 CHAPTER 2: LITERATURE REVIEW AND
BACKGROUND
2.1 HISTORY
In Rudolph Diesel’s 1893 paper "The Theory and Construction of a Rational Heat
Engine", the German inventor described a revolutionary engine in which air would be
compressed by a piston to a very high pressure thereby causing a sufficiently high
temperature to ignite non volatile oils (that is, to achieve compression ignition, CI, rather
than spark ignition, SI). His first working engine could run on various vegetable oils,
leading him to envision in 1911 that “the diesel engine can be fed with vegetable oils and
will help considerably in the development of the agriculture of the countries that use it”.
However, contrary to Mr. Diesel’s focus on vegetable oils, most CI engines since then
have run on petrodiesel and nearly all research has focused on how to improve the
performance and efficiency of engines using petroleum based fuel. Petrodiesel is safer to
store and transport than petrol, and CI diesel engines are both more robust and more
efficient (> 20% at high load) than SI petroleum engines. These advantages are reflected
in over seven percent of all crude oil being refined to diesel.
Many attempts have been made over the last century to use vegetable oils in CI engines
both in vehicles and for power generation. These have met with limited success, however,
since long term usage of straight vegetable oil causes problems like gumming and
Chapter 2: Literature Review and Background
8
deposits in the engine due to polymerization of vegetable oil. The combination of the
high viscosity and low volatility of vegetable oil caused delayed ignition and hampering
of engines. The relatively high freezing points and viscosities of vegetable oil limit their
use in cold conditions. However, with a few relatively simple modifications (such as fuel
preheating and altered engine timing), a standard CI engine can be made to run more-or-
less reliably and efficiently on vegetable oils such as coconut- or waste oils from food
industry (attempts to apply this strategy in the Pacific region are surveyed below).
Table 2.1 Diesel Substitutes Made From or Based on Vegetable Oil 13
Method Description Properties of fuel.
Pyrolysis
Thermal decomposition of triglycerides
affords, alkanes. Alkenes, alkadienes,
aromatic and carboxylic acids.
Low viscosity and high cetane
number compare to vegetable oil.
Acceptable amount of sulfur,
water and sediments.
Unacceptable ash carbon residue
and pour point.
Microemulsion
Stable dispersion of vegetable oil with
an ester and dispersant (cosolvent) or
of vegetable oil, an alcohol and
surfactant with or without diesel fuel.
The droplet diameter in a
microemulsion ranges from 100 Å -
1000 Å.
Reduced viscosity and nozzle
choking of the engine. But carbon
deposits on the injector nozzle
and exhaust valves.
Dilution
Vegetable oil diluted with diesel fuel or
solvent such as ethanol, paraffin and
naphthalene.
Reduced viscosity, heavy carbon
deposits causing nozzle choking.
Not appropriate for long term use
due to thickening of lubricants.
Transesterification
Chemical modification of edible oils
using methanol or ethanol to produce
methyl or ethyl fatty-acid esters.
Very similar or better properties
than diesel, rendering it the most
likely substitute for diesel fuel.
Chapter 2: Literature Review and Background
9
Attempts have also been made to modify the properties of vegetable oil fuel for use in
unmodified CI engines.
Here the physical properties of the fuel are altered and optimized for use in standard
diesel engines. The main methods devised for this purpose involve pyrolysis, dilution
and/or chemical modification (see Table 2.1). The latter is the only fuel modification
method so-far devised that produces a liquid with essentially the same fuel properties as
petrodiesel (see Table 2.2 and compare Figure 1.2).
Table 2.2 Fuel Properties of Biodiesel Compared to Conventional Diesel Fuel.
Fuel properties Soybean Methyl Ester
(B100)8
Petrodiesel
Viscosity (mm2/s) 4.41 (at 40 ºC) 38SSU14
Cetane number 48.2 40 – 5615
Flash Point (ºC) 174 5614
Cloud Point (ºC) 1 -314
Pour Point (ºC) -4 -1216
2.2 GLOBAL PERSPECTIVE AND BIODIESEL STANDARDS
The introduction of a biodiesel industry has reduced an unhealthy reliance on foreign
fossil fuel in many countries around the world including Europe, Africa, America, Asia
and the Pacific. The increasing usage, as well as research and production interest in this
field, has spurred the need to have standards for biodiesel fuel. Standardisation of
biodiesel is essential for its marketing and commercialisation. Specifications are
necessary for authorities to maintain the homogenous quality of the biodiesel fuel. Also,
there is a need to guarantee the safety and environmental credentials of the product.
Chapter 2: Literature Review and Background
10
The standards for biodiesel in Europe are set by the European Committee for
Standardization (CEN), of which many European countries are members. However, each
of these countries has its own biodiesel standards tailored to the climate and raw material
availability (Table 2.3). The result is a standard of acceptable levels for the chemical and
physical properties of biodiesel fuel.
Table 2.3 Biodiesel Fuel Standards in Europe Countries.
Europe Country Biodiesel Fuel Standard Protocol Used
Austria Austria Biodiesel Standards ON or ONORM
Czech Republic Czech Republic Biodiesel Standards CSN
European Union European Union Biodiesel Standards prEN
France France Biodiesel Standards Journal Officel
Germany German Biodiesel Standards DIN
Sweden Sweden Biodiesel Standards SS
Italy Italy Biodiesel Standards UNI
Biodiesel is made from several alternative edible oils and is referred to by various names,
including: Rapeseed Oil Methyl Ester (ROME), Fatty Acid MonoAlkyl Ester (FAMAE),
Fatty Acid Methyl Ester (FAME) and Vegetable Oil Methyl Ester (VOME) in Europe.
Coconut biodiesel (coconut oil methyl ester) is conveniently referred to as COCOHOL
(cf. Table 2.5 below).
In the USA and Canada (which use the ASTM D6951standard) biodiesel production is
encouraged by a tax incentives scheme which lowers the cost of biodiesel at the pump17
Other, countries such as Brazil, Korea, Japan and Argentina has modified the European
and ASTM biodiesel fuel standards to make them suitable for their climate, environment
Chapter 2: Literature Review and Background
11
and consumer demands. In the Pacific region, Australia has specifications gazetted under
Section 21 of the Fuel Quality Standard Act 2000 (see Table 2.4)
Table 2.4 Fuel Standards for Biodiesel in Australia 18.
Property Testing Method Limits Units
Acid number ASTM D 664 0.80 max mg KOH/g
Alcohol prEN 14110 0.20 %m/m
Carbon Residue 10% EN ISO 10370 0.30 %mass
100% ASTM D4530 0.05 %mass
Cetane Number EN ISO 5165 or ASTM D613 51 min
Contamination (total) EN 12662 or ASTM 5452 24 max mg/kg
Copper Strip Corrosion (3hrs @ 50°C)
ASTM D130 No. 3 max
Density @ 15°C ASTM D1298 or EN ISO 3675 860-890 kg/m3
Distillation 90ºC ASTM D160 360 max ºC
Ester Content prEN 14103 96.5 min %m/m
Flash Point ASTM D93 120 min ºC
Glycerol Free ASTM D6584 0.020 max % mass
Glycerol Total ASTM D6584 0.250 max % mass
Metal Group I (Na, K) prEN 14108 & prEN 14109 5 mg/kg
Metal Group I (Ca, Mg) prEN 14538 5 mg/kg
Oxidation Stability (6hrs) PrEN 14112 or ASTM
D2274 (per biodiesel) 110 ºC
Phosphorus ASTM D4951 10 mg/kg
Sulfur ASTM D5453 10 mg/kg
Sulfate Ash ASTM D874 0.02 % mass
Viscosity 40°C ASTM D445 3.5-5.0 mm2
/s Water and Sediment ASTM D2709 0.05 % vol
a) ASTM followed by an alphanumeric code means the testing method developed by ASTM
International under the alphanumeric code; and b) prEN, EN and ISO EN followed by number means that the testing method developed by the
European committee for Standardisation (CEN) under the code number.
Chapter 2: Literature Review and Background
12
2.3 REGIONAL PERSPECTIVE AND PRODUCTION
Copra from coconuts is a major agricultural crop in the Pacific region. It was once an
important export for Fiji. The demand for this crop from Pacific Island countries has
fallen markedly, thus affecting revenue earned through export and forcing countries to
venture into other industries to survive. Since it is endogenous, abundant in supply, and
with a perfect climate for production, this crop has been explored widely as a biofuel in
the region. A survey carried out by Pacific Islands Applied Geoscience Commission
(SOPAC) has studied the potential of domestic coconut oil as a source of renewable
energy. It confirms that a “large potential exists” (Figure 2.1)19.
Figure 2.1. Coconut Oil Production Potential and Exports of Pacific Island Countries19.
17.47
3.06 3.44
53.91
10.927.1
0 0.29
30.51
0
10
20
30
40
50
60
Am
ount
of C
ocon
ut O
il (M
illio
n Li
ters
)
Fiji Isl
ands
Kiribat
i
Mars
hal Is
land
s
Papua
New Guin
ea
Samoa
Solomon
Islan
ds
Tonga
Tuvalu
Vanuat
u
Pacific Island Countries
Coconut Oil Production and Exports in the Pacific Islands
Chapter 2: Literature Review and Background
13
Coconut oil has been reported as a source of fuel and/or additive in fuel mixtures in the
early 1980s in Fiji. Because of the abundance of coconuts in the region and because of its
physical and chemical properties, coconut oil and mixtures containing coconut oil and
coconut oil derivatives are being actively investigated.
Table 2.5 Coconut oil, Mixtures and Derivatives as Fuel in the Pacific.
Biofuel Aim of Investigation Methodology Findings • Neat esterified
coconut oil (COCOHOL)
• Mixture of COCOHOL and Kerosene.
Suitability of esterified coconut oil as fuel substitute in kerosene hurricane lamps
Hurricane lamps fuel with respective biofuel were lit and observed. The luminosity of the flame and the wick length was measure after intervals.
Mixtures of COCOHOL and kerosene were acceptable substitutes for fuel in the lamps, with 10% COCOHOL mix performing as well as Kerosene 20.
• Coconut oil ethyl ester
The efficiency of ethyl esters as a substitute for petroleum fuel in domestic lamps and stoves was investigated
The combustion efficiency of ethyl ester and kerosene fuel was compared.
Coconut oil ethyl esters are as equally efficient as petroleum fuel for providing energy for domestic cooking and lightening in rural Pacific Island nations 21.
• Coconut oil • COCOHOL
esterified coconut oil
The performance of both coconut oil and esterified coconut oil COCOHOL as fuel was investigated on diesel engines.
The miscibility of each fuel with diesel oil was studied together with the thermal efficiency of fuel with engine loading.
• Coconut oil was found to be immiscible with diesel oil with decreasing efficiency with high engine loading. As a fuel coconut oil was found to be problematic during low temperatures.
• COCOHOL was miscible with diesel oil, ethanol and coconut oil. COCOHOL and ethanol blended fuel was observed to be as efficient as diesel oil even at high engine load. Less cylinder choking and exhaust smoke was reported 22.
• Coconut oil Specific fuel consumption
and contamination of fuel due to engine wear was studied using different fuel.
Coconut oil was blended with distillate diesel fuel and compare with results from using diesel fuel in engines.
Fuel containing coconut oil blend appeared to show reduced engine wear indicated by metal contamination in fuel 23.
Chapter 2: Literature Review and Background
14
Research on the efficiency of coconut oil and its derivatives as biofuel has been carried
out previously in Fiji20-23. However, the sources of coconut oil derivatives and methods of
production were not specified. The quality of the derivatized product was also not
examined, implying inconsistency in the engine efficiency results obtained from these
biofuels.
More recent energy-resource studies in Fiji have expanded the information on coconut oil
as biofuel. An joint initiative by Fiji Government, Department of Energy and SOPAC has
calculated that the total energy available from local coconuts is sufficient to cater for the
energy need of rural villages in Taveuni and Vanua Balavu. These projects have attracted
the support of the French Government and SPC-CIRAD24.
Figure 2.2 Biodiesel Batch Process Plant at Lami.
This plant was set up in 1982 for small batch process biodiesel production from coconut oil in Fiji.
Chapter 2: Literature Review and Background
15
Research on liquid biofuels in Pacific Island countries has shown that most island nations
could use coconut oil to supplement their energy requirements either in form of blended
mixtures or neat oil. Coconut oil produced in these island countries has a retail price
comparable with diesel or (esp. in recent times) considerably lower. Biofuel has become a
commercial product in the Solomon Islands, Papua New Guinea and Vanuatu. In
Vanuatu, “Island Fuel 80” is retailed at US$0.30 less than conventional diesel fuel. Island
Fuel 80 is a blend of 80% coconut oil and 20% kerosene that was trialed and optimized
for several years in the Port Vila Toyota dealership with excellent results for vehicle
maintenance and running costs before being up-scaled for commercial use. Following the
success of blended biofuel in Vanuatu, Samoa and the Solomon Islands have taken
initiatives to implement it in their countries. Blends of coconut oil with diesel have been
tested on government vehicles in Kiribati, while coconut oil has been used unsuccessfully
as fuel in diesel engines in the Marshal Islands19.
Of relevance to the local situation, there is a good deal of information about the
production and use of bio-diesel in the Philippines and Hawaii to draw upon; including
low-tech methods of producing coconut biodiesel and used-cooking-oil biodiesel in
isolated centers. Both countries have established commercial plants for mass production
and operate commercially, encouraging the use of biodiesel as an alternative renewable
energy fuel.
Chapter 2: Literature Review and Background
16
There is therefore an expanding need to research and establish a protocol for biodiesel
production and its quality control specifying appropriate standardisation in order to
generate a consistent sustainable renewable fuel with similar benefits.
2.4 ENVIRONMENTAL BENEFITS OF BIODIESEL
Concern about the health and environmental effects of diesel has played a major role in
spurring the recent upsurge of interest in biodiesel. Diesel exhaust is very toxic: it is a
known cause of lung cancer25 and more recently a strong link with heart disease has been
established26. Diesel soot contains polycyclic aromatic hydrocarbons (PAH) such as, (a)
pyrene, (b) benzo(a)pyrene and (c) nitropyrene which being lipophilic and slow to
metabolize are accumulated by humans (see Fig. 2.3).
Figure 2.3 Some PAHs Emitted from Diesel Exhaust
Not only these compounds (formed via incomplete burning of diesel) known to cause
adverse health effect to humans but the PAH’s in diesel soot may also react with OH and
a) pyrene
b) benzo(a)pyrene
NO2
c) Nitropyrene
Chapter 2: Literature Review and Background
17
NO3 radicals in the atmosphere to produce substances that have an even greater
mutagenic and carcinogenic property than the original hydrocarbons27.
The burning of diesel is a major contributor to the global man-made carbon dioxide
production that (according to a consensus of scientists) is responsible for a net global
warming effect that contributes to worsening environmental problems like intense storms
and rising sea levels. Atmospheric carbon dioxide concentration has increased over the
last decade at an alarming rate of 1.6ppm per year28. Biodiesel is derived mainly from
‘living carbon’ rather than fossil carbon. For living carbon, as much carbon is absorbed
from the atmosphere during its formation (in vegetable matter) as is released when it is
burned. This makes biodiesel as a renewable and sustainable energy resource; a resource
that is an integral part of the “Green Revolution Solution” to make the global
environment cleaner and safer to live in.
Notable quote: "In May 2000, bio-diesel became the only alternative fuel to successfully
complete the Environmental Protection Agency's Tier I and Tier II testing under Section
211 (b) of the Clean Air Act. The Department of Energy and the U.S. Department of
Agriculture have calculated carbon dioxide reductions of 78 percent for bio-diesel when
compared with petroleum diesel in a full life cycle analysis. Bio-diesel also reduces air
pollutants linked to cancer by 80-90 percent vs. petroleum diesel”29
Biodiesel fuel is essentially harmless to humans; indeed, France classifies biodiesel as a
‘food’ in its regulations pertaining to the transport of hazardous materials. The vapor is
non-poisonous and non-intoxicating to breathe (or even to ingest in small quantities),
whereas petroleum fuels contain aromatic compounds - such as benzene, xylene and
Chapter 2: Literature Review and Background
18
toluene - known to be acutely toxic as well as carcinogenic. When biodiesel is burned in a
diesel engine it produces less emissions and those emissions that are less toxic than for
petrodiesel. The methyl and ethyl esters of fatty acids are partially oxygenated
hydrocarbons; the CO2 groups contained in their structures improve combustion
efficiency, resulting in cleaner exhaust, less soot formation and lower carbon monoxide
emissions10. Moreover, any unburned fuel contained in the exhaust is less toxic for this
biofuel than for fossil fuel (see above). Unlike petrodiesel, biodiesel is naturally
lubricating (has a high ‘lubricity’) eliminating the need for sulfur-containing additives; it
therefore displays a 100% reduction in sulfur emission. This is significant because sulfate
in emissions generates sulfuric acid causing corrosive acid rain.
Table 2.6 Emission Change in Biodiesel and Blended Biodiesel Fuel5.
Neat Biodiesel (B100)* Blended Biodiesel (B20)**
Carbon Monoxide (CO) -43.2% -12.6%
Hydrocarbons (HC) -56.3% -11.0%
Particulate Matter (PM) -55.4% -18.0%
Nitrogen Oxides (NOx) +5.8% +1.2%
Air toxics -60% to –90% -12% to –20%
Mutagenicity -80% to –90% -20%
Carbon dioxide*** -78.3% -15.7%
*Average of data from 14 EPA FTP Heavy Duty Test Cycle tests, variety of stock engines **Average of data from 14 EPA FTP Heavy Duty Cycle tests, variety of stock engines ***Life cycle emissions
Toxic emissions. As shown in Table 2.6, biodiesel or its diesel blend B20 is much better
for the environment than petrodiesel, with a small (6%) increase in NOx production more
than offset by large reductions in toxic and particulate emissions.
Chapter 2: Literature Review and Background
19
Carbon dioxide. The use of plant-based renewable raw materials to produce biodiesel fuel
aids in recycling carbon dioxide emitted from vehicles: the carbon dioxide is derived
from plants and is absorbed back into the plants that are the raw material for biodiesel
production. Unlike the more controversial situation with cultivated crops (for which large
amounts of fossil-carbon-derived energy is expended in tilling, fertilizing, harvesting and
transport)30 biodiesel fuel from free-growing tropical crops like coconut qualifies as a
carbon neutral product.
Ozone. Emissions from ethanol-gasoline mixtures (in particular, the E85 or 85% ethanol
+ 15% gasoline mixture) contain formaldehyde and acetaldehyde, which have been
reported to increase ozone-related mortality and hospitalization compared to emissions
from fossil gasoline31. By contrast, the emissions from neat biodiesel significantly reduce
production of ozone-forming hydrocarbons.32
Biodegradation. Biodiesel undergoes rapid degradation by microbes in both terrestrial
and in aquatic environments33. Blended biodiesel is degraded more rapidly than pure
petrodiesel in the environment. Indeed, the addition of vegetable oil (or biodiesel) to
diesel or crude oil spills on water leads to accelerated biodegradation and clean-up. This
is an important attribute for sensitive coral-reef and small-island habitats as any fuel spills
that might occur would be relatively harmless to humans, plants and animals.
The next chapter investigates the raw materials available in Fiji for biodiesel production.
It identifies the most suitable lipid source through a series of chemical and physical
Chapter 2: Literature Review and Background
20
analysis. To determine the synthetic pathway of biodiesel as final product, the quality of
the lipid source is essential to obtain
Chapter 3 Raw Materials – Feedstock Availability and Analysis
21
3 CHAPTER 3 – RAW MATERIALS – FEEDSTOCK
AVAILABILITY AND ANALYSIS
3.1 INTRODUCTION
Raw materials for biodiesel production need to be selected according to their
availability and cost in the country or region. Economic feasibility studies of large-
scale production of vegetable oil-derived fuel have indicated that the raw materials
contribute 85-95% of the total production cost34. The production cost of biodiesel
depends mainly on feedstock cost even when there are low conversion yields35. This
underscores the importance of selecting the appropriate feedstock in a sustainable
biodiesel production process.
Equally important is the quality of raw materials used for production of biodiesel fuel.
Raw materials generally need to undergo treatment to upgrade the source materials to
acceptable quality. The chemical composition and the physical properties of source
materials affect both the production efficiency and the performance of the final
product. Chemical properties including free fatty acid content, phosphorus content
and iodine value determine the suitability of the lipid feedstock. Physical properties
such as moisture content and viscosity are also important for the production process.
A third consideration is the energy required to produce the oil. This includes energy
for cultivating, harvesting and extracting the lipid from the crop. For free-growing
lipid sources the energy overheads are smaller but we still need to consider labour
Chapter 3 Raw Materials – Feedstock Availability and Analysis
22
energy, facility energy and transportation energy. These energy factors need to be
minimised in order to gain a maximum benefit of biodiesel as an alternative fuel.
This chapter reports the first phase of my research project in which suitable biodiesel
lipid feedstocks were identified and the quality of local raw materials was
experimentally examined. This data-gathering phase of the work was done with the
assistance of survey reports and regional studies made available by SOPAC and
gathered while on secondment at their Mead Road offices. The method development
and the analysis were performed in the Chemistry Department of the USP.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
23
3.2 IDENTIFYING & SURVEYING EDIBLE OIL
FEEDSTOCKS.
3.2.1 Lipid source material
The bulk of the energy in the lipids of plants and animals is held in the glycerol-based
fats and oils.
Figure 3.1 Lipid Classes and Some Fatty Acids and Found in Edible Oils.
H2C
CH
H2C
O
O
C
O
R
C
O
R
OCR
O CO
OH
oleic acid (C18:1)
Free Fatty Acid, FFA RCO2H =
C
O
OH
lauric acid (C12:0)
C
O
OHmyristic acid (C14:0)
triglyceride (TG)
H2C
CH
H2C
O
OH
C
O
R
OCR
O
diglyceride (DG)
H2C
CH
H2C
OH
OH
OCR
O
monoglyceride (MG)
H2C
CH
H2C
OH
OH
HO
glycerol (G)
C
O
OH
linoleic acid (C18:2)
C
O
OH
palmitic acid (C16:0)
CO
OH
LIPID CLASSES SOME FATTY ACIDS IN EDIBLE OILS
arachidonic acid (C20:4)
major FA in canola& soyabean oil& hence 'waste oil'
polyunsaturated FA (PUFA) in sunflower oil& safflower oil
major FA in palm oil (esp. in palm fat)
an omega-6 fatty acid found in meat & egg yolk; cf. linolenic acid (C20:3), an omega-3 FA in fish oil.
major fatty acids in coconut oil
ω−13
6
Chapter 3 Raw Materials – Feedstock Availability and Analysis
24
Triglycerides (TG) along with varying smaller amounts of diglycerides (DG),
monoglycerides (MG) and free fatty acids (FFAs) make up the typical composition of
an oil or fat (see Fig. 3.1, noting that DG and MG are actually random mixtures of
positional isomers of the indicated glyceryl esters).
Early research in biodiesel production indicated that soybean oil, rapeseed oil and
sunflower oil were suitable lipid feedstocks. They met the criteria:
“To be a viable substitute for a fossil fuel, an alternative fuel should not only have
superior environmental benefits over the fossil fuel it displaces, be economically
competitive with it, and to be reproducible in sufficient quantities to make meaningful
impacts on energy demands, but it should also provide a net energy gain over the
energy sources used to produce it”30.
However, feasibility and sustainability assessments have pointed out problems with
this strategy; that the use of new oil from cultivated crops would detract from food
supplies and that it would be better to use low-grade or waste oil for biodiesel
production since an added demand for edible oil would drive up food prices. It was
found that biodiesel of similar quality and engine performance could be guaranteed
using a feedstock that is non-edible.
Suitable Feedstocks. The feedstock oil is made up of glycerides with varying fatty-
acid chain lengths and saturation (see Figure 3.1 for some examples). The fatty acid
composition of the oil is reflected in the properties of the final derivatized fuel, which
is simply the corresponding mixture of methyl (or ethyl) esters of the fatty acids
present in the glycerol lipid (cf. Figs 1.1 & 1.2).
Chapter 3 Raw Materials – Feedstock Availability and Analysis
25
Most vegetable and animal oils and fats (TGs) give alkyl esters that are satisfactory
(in terms of viscosity, energy content, cetane rating etc.) as substitutes for petrodiesel.
However, long-chain saturated fatty acid esters tend to have too high a melting point;
e.g. pure methyl stearate, Me18:0, has melts at 38 °C, precluding the use of (say)
methyl “beef tallow biodiesel” as a major component of pure or blended biodiesel.
While biodiesels made from highly unsaturated oils (as in high-PUFA oils from
safflower and linseed, e.g.) tend to undergo rapid and extensive autoxidation reactions.
C
CO
OMe
methyl linolenate in, say, fish oil- or flax oil biodiesel
H
H
HH
especially weak C-H bonds - undergo rapid autoxidation
ω−3
Autoxidation is the slow spontaneous reaction with oxygen. The weakest bonds in a
molecule participate most readily. PUFA oils and their derivatives have large concentrations
of the “bisallylic methylene” groups indicated above. The first stage is a free-radical reaction
that inserts molecular oxygen (from air) into these CH bonds..
C
H H
C
H O OH
lipid lipid hydroperoxide
O2 (from air), radical catalyzed
peroxidation
This peroxidation step results in a cascade of further reactions of the hydroperoxides
(including cyclization, cross-linking, polymerization, β-scission and condensation reactions)
that leads to oxygen-lipid co-polymers (cf. setting of linseed oil varnish) and formation in lipid
biofuel of gums and gels. – See, e.g.36
Thus, provided the freezing point is not too high, a more stable – longer shelf-life –
biodiesel can be made from mainly saturated oils like coconut and palm oils than from
Chapter 3 Raw Materials – Feedstock Availability and Analysis
26
high-PUFA oils like sunflower. Mainly mono-unsaturated oils like soybean and
canola oils (containing mainly oleic acid) afford biodiesels that are somewhat
oxidizable but with lower freeze & cloud points suitable for cooler climates.
A survey of the literature shows that biodiesel production typically uses several edible
oils that are also agricultural crops. These include: soybean oil37,38, rapeseed oil39,38,
corn oil40, coconut (copra)oil, palm kernel oil41, palm oil42, canola oil43,38, olive oil44,
sunflower oil45,46,47, hazelnut oil47, linseed oil48 , safflower oil48, castor oil49, fish oil50,
rice bran oil51, cotton seed, poppy seed oil40, nut sedge oil52, and Camelina oil
(Camelina sativa)43. Alternative lipid sources derived from food material not fit for
consumption include low grade salmon oil54 and heat damaged canola oil seeds55.
Non-edible lipids. These have been a recent “hot topic” for researchers who have
endeavoured to find organisms with high lipid content that is suitable for biodiesel
production. Azam et al, (2005)56 examined the fatty acid methyl esters of 75 oil-seed
and kernel-plant species and evaluated their use as biodiesel fuel. Fatty acid methyl
esters of 37 of the plant species studied were found to comply with major biodiesel
specifications of USA, Germany and the European Standard Organisation. The non-
edible plants species that can survive in marginal, non-cropped land included:
Jatropha (Jatropha curcas)57, Azadirachta indica, Calophyllum inophyllum, and
Pongamia pinnata. Other non-edible plant seeds that have been investigated as a lipid
raw material for biodiesel production are tobacco (Nicotiana tabacum. L)58, Mahua
(Madhuca indica) 59, Karanja (Pongamia glabra)60 and rubber seed oil61
Chapter 3 Raw Materials – Feedstock Availability and Analysis
27
Waste Oil. Used frying oil or waste oil is inferior in quality to fresh vegetable oil.
Being cheap or even free, however, it is a popular raw material for biodiesel
production62,63,64,43, especially for medium, small and ‘backyard’ operations. The
composition of used frying oil is complicated by its history of interaction between the
frying oil and the food material being fried. Some of the lipids from the frying food
become mixed with the frying oil, which will therefore often contain chicken and/or
beef fat. Thermal, oxidative and hydrolytic reactions occur during the frying process
resulting in formation of free radical products (see above), Schiff-base addition
products and volatile compounds like amides, acid nitriles, alkyl pyridines and
pyrroles65. All these induce physical and chemical changes to the oil such as increased
free fatty acid content, and viscosity, decreased iodine value, development of darker
colour and change in refractive index.
As with used frying oil62,66,67, tallow, lard37, meat bone meal68 and animal fat all have
naturally high free fatty-acids content. Canakci et al (2003)35 have conveniently
divided these feedstocks into yellow grease and brown grease relative to their free
fatty acid content of 9% max and 40% max, respectively. A two step synthesis
process resulting is 91% product yield has been reported for brown grease, showing
that even highly degraded frying fats and oils are viable for making biodiesel.
Lipids as raw materials have also been sourced from soap stock69,70 a by-product of
edible oil and rendered fat refining. Lipid filtered out from municipal sewage sludge71
has been explored as raw material for biodiesel production. The microbial algae72,73
Chlorella protothecoids, has been found to contain 55% of an crude lipid (mainly
Chapter 3 Raw Materials – Feedstock Availability and Analysis
28
composed of oleic acid and linoleic acid) that can be extracted and transesterified
using acid catalyst (see below) to produce biodiesel.
3.2.2 Alcohol as raw material
The most common type of alcohol used for transesterification is methanol due to its
ready availability and ease of use. Industrially, methanol is made in vast quantities
from natural gas via high temperature catalytic processes.
CH4 + H2O → CO + 3 H2 (Ni cat., 10-20 atm, 850 °C)
CO + 2 H2 → CH3OH (Cu-Zn-alumina cat., 50-100 atm., 250 °C)
Methanol is therefore quite cheap as a starting point for production of fuels and has a
comparatively small carbon footprint (since methane contains only one fossil carbon
per molecule). Methanol is principally used to make formaldehyde (for further
synthesis), to make fuel additives (like methyl t-butyl ether) and, increasingly, for the
production of biodiesel. However, in colder climates methyl biodiesels may have
unacceptably high melting points and cloud points. Biodiesels made with longer
alcohol chains (with ethanol, propanol etc.) have lower melting point/cloud points
than the corresponding methyl esters.
Ethanol. Ethyl alcohol offers an attractive alternative to methanol because ethanol is
less toxic and it is derived from a renewable energy source (from sugars made from
sugar cane, cassava etc.) that might be locally produced rather than imported. One
problem with ethanol is water: ethanol forms an azeotrope with water (96:4
ethanol/H2O) so it cannot be dried for biodiesel production – where it must be dry so
Chapter 3 Raw Materials – Feedstock Availability and Analysis
29
as not to inactivate the catalyst - using simple distillation (unlike methanol) (this is
also a hurdle to local production of dry ethanol as a petrol additive). Another problem
with ethanol (reported elsewhere and confirmed in this work) is that it tends to form
an emulsion after transesterification of oil, making separation of ester and glycerol
difficult. Mixtures of methanol and ethanol have been used to improve the solvent
properties and improve equilibrium conversion rate of esters74. Other alkyl alcohols
like t-butyl-, n-butyl-, n-propyl- and iso-propyl alcohols {(CH3)3COH,
CH3CH2CH2CH2OH, CH3CH2CH2OH, and (CH3)2CHOH} have been investigated as
raw materials for biodiesel production75. Of these, isopropyl alcohol (2-propanol) is
the cheapest but shares the ecological disadvantage of the others of being derived
from fossil oil.
Non-catalyzed Biodiesel Formation. Under supercritical treatment, alcohol is
subjected to supercritical temperature and pressure. Supercritical fluids have
thermophysical properties (such as dielectric constant, viscosity, specific gravity and
polarity) that are markedly different from the non supercritical solvents they are
produced from. Methanol has a critical temperature and pressure of 512.2K (239 °C)
and 8.1MPa (8,000 atm.!) respectively76. Reaction conditions can get as extreme as
350 ºC and 20-50MPa. The use of supercritical methanol as a reactant in biodiesel
production process vastly improves the ester formation efficiency, with yields as high
as 95% obtained in 10 minutes76. Supercritical alcohol can even be used with lipid
sources containing high free fatty acid content, without any pre-treatment process
being required. Little or no catalyst is required for the transesterification process
yielding high purity biodiesel. It is clear, however, that this non catalytic process is
Chapter 3 Raw Materials – Feedstock Availability and Analysis
30
not economically viable outside a major industrial complex, as reaction conditions are
very drastic.
3.2.3 Catalysts
There are several advantages and disadvantages of the various types of catalyst that
have been used in the biodiesel production. Recent research has focussed on
developing efficient and economically viable catalysts for biodiesel production.
Table 3.1 Comparisons Between Alkaline and Acidic Catalyst
Alkaline Catalyst
Advantages Disadvantages
• Higher conversion rate (4,000 times
faster) of esters under mild conditions
as compared to same amount of acid
catalyst equivalent.
• Smaller amounts are required
compared to acid catalysis.
• Compatible or less corrosive to
industrial equipment as compared to
acid catalysis. Normal carbon steel
based reactor materials can be used
• Alkali catalyst has limited usage with
low-grade lipid raw material. It gets
neutralized (destroyed) in the presence
of high free fatty acids in oil. This is
usually overcome by introducing a pre-
treatment process before
transesterification, which is an added
cost factor in biodiesel production
process.
Acid Catalyst
Advantages Disadvantages
• Can also be used with low grade oil
having high free fatty acids as acidic
catalyst would still be effective.
• Requires drastic reaction conditions
involving high temperature and
pressure for transesterification, making
it dangerous to work with.
Homogeneous alkaline catalysts include alkali metals, alkali metal alcoholates and
hydroxides, aqueous metal hydroxide solutions and strong organic bases.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
31
Heterogeneous alkaline catalysts include alkali-metal hydrogen carbonates, alkali-
metal oxides, alkaline-earth metal alcoholates, alkaline-earth metal oxides, alkaline-
earth metal hydroxides, strong anion exchange resins and alkali metal and alkaline
earth metal carbonates and salts of carboxylic acids. Homogenous acid catalysts
include mineral acids, aliphatic and aromatic sulfonic acids, as well as lipid-soluble
lewis acids like InI3. Strong cation exchange resin and metal phosphates are some of
the heterogenous acid catalyst77 that have been investigated. Transition metals and
silicated compounds have also been tried. Enzymatic catalysis process has been
applied to the transesterification of biodiesel, although, to date78, there are no
commercially viable processes based on enzymatic catalysts.
Summary
There are strong environmental, health, economic and energy-cost arguments for the
production and use of vegetable oils as a substitute for petrodiesel, especially in
regions that can utilize ‘free-growing’ feedstocks like coconut oil. Its net energy
balance (NEB) is overwhelmingly (93%) positive compared to other biofuels like
ethanol (25%)30. This means that biodiesel yields 93% more energy than the energy
required for its production and processing. Renewable energy that are non food based
or from waste biomass and benefit positively to environment could provide for much
greater supplies and have merit for being available at a cheaper cost.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
32
3.3 METHODOLOGY: ANALYSIS OF RAW MATERIALS
In this study, commercial oil samples and used vegetable cooking oil (waste oil)
were collected using the sampling methodology described below. The method was
designed to get a representative sampling of the whole population of each type of oil.
Each sample was later analysed for it chemical (free fatty acid content, iodine value
and phosphorous content) and physical (moisture content) properties (Figure 3.1).
This quality control protocol indicates the quality of the lipid source and suggests
which synthetic pathway to follow in order to produce quality biodiesel.
Figure 3.2 Chemical and Physical Analysis of Lipid Raw Materials
Fatty acid composition of waste oil (used oil) does not stay same and is not consistent.
In addition to the frying oil itself, fats and oils originating from foods that were fried
in the oil contribute to the fatty acid composition of the used vegetable oil.
FEEDSTOCK
2) Commercial Oil
1) Waste Oil
CHEMICAL ANALYSIS
1) Iodine Value
3) Phosphorous Content
2) Free Fatty Acids
PHYSICAL ANALYSIS
1) Moisture and VolatileMatter
Chapter 3 Raw Materials – Feedstock Availability and Analysis
33
Table 3.2 Fatty Acid Composition of Commercial Oil Samples Analysed6.
Fatty acid composition ( wt %)
Oil 12:0
Lauric
Acid
14:0
Myristic
Acid
16:0
Palmitic
Acid
18:0
Stearic Acid
18:1
Oleic Acid
18:2
Linoleic
Acid
18:3
Linolenic
Acid
22:1
Erucic
Acid
Soybean Oil 2.3-11.0 2.4-6.0 49.0-53.0* 22.0-30.8 2.0-10.5
Canola Oil 4.0-5.0 1.0-2.0 55.0-63.0* 20.0-31.0 9.0-10.0 1.0-2.0
Coconut Oil 44.0-51.0* 13.0-18.5 7.5-10.5 1.0-3.0 5.0-8.2 1.0-2.6
* Major fatty acid component of the oil type.
3.3.1 Sampling methods
Commercial oil
The commercial bottled oils collected were soybean oil, canola oil and coconut oil.
The oil samples were refined quality edible oils bought from different supermarkets at
different times to ensure fair representation. There are two dominant commercial
suppliers of vegetable oil in Fiji, bottled oil from each supplier was labelled as brand
one and brand two. Random buying of samples for each brand of oil was carried out
in triplicates.
Waste oil
Waste oil was sampled from three different restaurants and fast food outlets around
Suva. These fast food outlets were chosen as they are reputable and use the same
frying oil in all there branches throughout Fiji.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
34
Table 3.3 Lipid Source Before Use from Three Different Outlets.
Used oil Source Original Lipid Before Use Major fat ty acid component
Source 1 Palm shortening Palmitic acid
Source 2 Soybean shortening Oleic acid
Source 3 Soybean oil Oleic acid
Random sampling from each location was carried out in triplicate. The waste oil
samples were collected in acid washed plastic bottles and filtered with cellulose filter
paper to remove small particulate matter originating from food fried in the oil. The
filtered oils were collected and stored in glass bottles at room temperature until
analysed for its chemical and physical properties.
3.3.2 Chemical Analysis
3.3.2.1 Free Fatty Acid (FFA)
(A.O.C.S. Official Method Ca 5a-40)79
The Acid Value is defined as the number of milligrams of potassium hydroxide
required to neutralize 1.0 g of an organic substance. This quantity is related to the free
fatty acid content via the mean molar mass of the fatty acid in the particular oil (mass
% of FFA in the oil).
PROCEDURE
Each oil sample was homogenised by inverting the bottle several times before
weighing out the required amount of oil (see table below) in an Erlenmeyer flask
using an analytical balance. The oil was dissolved in the required volume of
neutralised ethanol. Five drops of phenolphthalein indicator was added, and the
Chapter 3 Raw Materials – Feedstock Availability and Analysis
35
magnetically stirred mixture was titrated with 1.0N sodium hydroxide at 60°C to a
pale-pink end point.
Commercial oils were weighed out directly from the bottle. Free fatty acid content
analysis of each type of oil of a particular brand was carried out in triplicates and the
average free fatty acid content was obtained. For each type of commercial oil the
fatty acid was calculated based on the major fatty acid component it contained (Table
3.2 Fatty Acid Composition of Oils Analysed6)
Waste oil that was not liquid at room temperature was heated to melt and cooled
down to room temperature then weighed out. FFA content analysis was carried out in
triplicates and the average value was reported.
Table 3.4 Specifications according to A.O.C.S Ca 5a-40
F.F.A Range (%) Grams of Sample Alcohol (ml) Strength of Alkali
(N)
0.00-0.2 56.4±0.2 50 0.1
0.2-0.1 28.2±0.2 50 0.1
1.0-30.0 7.05±0.05 75 0.25
*30.0-50.0 7.05±0.05 100 0.25-1.0
50.0-100 3.525±.001 100 1.0
*Average % range of lauric acid (major component) in coconut oil.
The mass of sample, alcohol volume and the strength of alkali were determined using
Table 3.4. Calculation of the FFA content depended on the particular oil being tested
as per the following example of coconut oil (44-51% lauric acid).
Chapter 3 Raw Materials – Feedstock Availability and Analysis
36
CALCULATION
The percentage of free fatty acids in coconut oil is expressed as lauric acid.
i. Free Fatty acids as lauric,% = vol. of NaOH (ml) x N x 200 x 100%
1000 x Weight of sample (g)
Where:
N = normality of NaOH solution
Use the following constants respectively (Table 3.5):
Constant 200 = molecular weight of lauric acid.
Constant 282 = molecular weight of oleic acid.
Constant 256 = molecular weight of palmitic acid.
ii. Acid Value* = vol. of NaOH (ml) x N x 56.1
Weight of sample (g)
Where:
Acid value = mg of KOH required to neutralise acid in 1 g of sample (as per
definition).
N = normality of NaOH solution
56.1 = molecular weight of KOH
Table 3.5 Free Fatty Acid Values Reported as the Respective Fatty Acid
Oil sample Free fatty acid calculated as
Commercial oil
Soybean oil Oleic Acid
Canola oil Oleic Acid
Coconut oil Lauric Acid
Waste oil
Source 1(a) Palmitic acid
Source 2(b) Oleic acid
Source 3(c) Oleic acid
(a) source 1 used palm shortening for cooking; (b) source 2 used soybean shortening for cooking and (c)
source 3 used soybean oil for cooking
* the FFA% content was calculated as the respective FFA as these fatty acids are major components of
the lipid source.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
37
3.3.2.2 Iodine Value (Wijs’ Method)
(A. O. C. S. Official Method Cd 1-25)80
Iodine value measures the level of unsaturation determined by volumetric titration. It
is expressed as the percentage of iodine absorbed by the sample i.e. number of grams
of iodine absorbed by 100g of sample. In the original method an excess of Wijs’
solution (0.2N ICl in CCl4) is added to the oil; the excess ICl is converted to I2 by
adding KI solution and the I2 is then titrated with Na2S2O3 solution. The difference
between a blank titration and the oil containing titration gives the iodine value of the
oil. The original method (Wijs method) was modified according to a publication by
Pocklington, 199081. Modification involved the use of a 1:1 mixture of cyclohexane
and glacial acetic acid as solvent instead of carbon tetrachloride (which is
carcinogenic).
PROCEDURE – SAMPLE AND BLANK PREPARATION
Both commercial oil and waste oil were analysed using the following procedure.
Sample
The recommended mass of homogenised oil sample was added Wij’s solution to an
excess of 50-60% i.e 100-150% of the amount absorbed (Table 3.6). To the sample,
20ml of 1:1 mixture of cyclohexane and glacial acetic acid and 25ml of Wijs solution
(0.2N ICI solution) was added, consecutively. The mixture was stored in the dark for
30 minutes at room temperature. Then, added 20 ml of potassium iodide was added to
the solution followed by 100 ml of distilled water.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
38
Table 3.6 Recommended Masses of Sample for Iodine Value.
Sample weight Sample Iodine Value less
than…. 100% excess 150% excess
Coconut oil 20 1.5865 0.8461
Soybean oil 140 0.2266 0.1813
Canola oil 120 0.2644 0.2115
Palm oil 60 0.5288 0.4231
Blank
The blank was prepared by mixing the reagents in same quantity and storing for the
same time under the same conditions as for the sample. That is to say, the same
procedure was used for the blank as for the sample except the oil sample was not
added.
The resulting solution (sample or blank) were titrated with 0.1N sodium thiosulfate
using starch indicator (2 ml). Three trials were done for each sample.
CALCULATION
The iodine value = (B-S) x N x 12.69
Weight of sample
Where:
B = titration of blank
S = titration of sample
N = normality of Na2S2O3 solution.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
39
STANDARDISING SODIUM THIOSULPHATE SOLUTION
To 25ml of standard 0.100 N potassium dichromate solution (prepared by dissolving
4.900g in 1.000ι distilled water) in a conical flask, was added 25ml of hydrochloric
acid and 10ml of potassium iodide solution. The solution was swirled then allowed to
stand for 5 minutes before adding 100ml of distilled water and titrating it with sodium
thiosulfate solution until the yellow colour became pale upon which starch indicator
was added and titration continued till the bluish black colour disappeared to form a
colourless mixture. The normality of sodium thiosulphate was calculated using the
following equation.
Normality of Na2S2O3 solution = 2.5
Sodium thiosulfate solution required (ml)
3.3.2.3 Phosphorus Analysis
(A.O.C.S. Official Method Ca 12-55)82
This method involves ashing the oil sample in the presence of zinc oxide followed by
a colorimetric measurement of phosphorous as molybdenum blue. It determines the
phosphorous or the phosphorous equivalent phosphatide content in the oil sample.
PROCEDURE
Both commercial oil and waste oil was analysed using the following procedure.
Glassware treatment.
All glassware used for this analysis were rinsed with distilled water and carefully
soaked in warm 1M HCl solution for 4 hours. Then it was rinsed with fresh distilled
Chapter 3 Raw Materials – Feedstock Availability and Analysis
40
water and soaked in 1M HCl water bath for 12 hours before rinsing it with distilled
water and ensuring it is dry ready to use.
Sample (Ashing)
For each oil, a 3.05 ± 0.05g sample was weighed in a Vycor crucible and 0.5g of zinc
oxide was added. The mixture was heated until it thickened and the heat was then
increased to completely char. The sample crucible was then placed in the muffle in
the furnace at 550°C for 2 hours. After cooling to room temperature 5ml of distilled
water was added to the crucible along with 5ml of concentrated hydrochloric acid.
The crucible was covered and gently heated for 5 minutes over a hot plate.
The mixture was filtered into a 100ml volumetric flask and the filter paper was rinsed
with four 5ml hot distilled water washings of the crucible (including the lid). The
filtrate was cooled to room temperature and 50% potassium hydroxide was added to
neutralise the mixture to a slightly faint turbid solution. Upon doing this, zinc oxide
precipitates out of the solution; it was dissolved by adding 2 drops of concentrated
hydrochloric acid to get a clear solution. The solution was then made up to the mark
by adding distilled water and mixing thoroughly.
A 10 ml aliquot of this solution was quickly pipetted out into a clean dry 50 ml
volumetric flask and 8ml of 0.015 % hydrazine sulphate and then 2 ml of sodium
molybdate were added. The mixture was stoppered and inverted several times, then
heated for 10 minutes in a water bath at 100°C. The mixture was cooled to room
temperature (water bath) and finally topped up to the mark with distilled water. It was
mixed and transferred to a clean dry glass cuvette ready for analysis.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
41
Blank
The same procedure for sample preparation was followed except no oil sample was
used.
Standards
The volumes that are indicated in Table 3.7 of 0.01mg/ml standard phosphate solution
were pipetted into 50ml volumetric flasks to prepare the corresponding phosphorous
standards.
Table 3.7 Preparation of Phosphorous Standards
Standard Volume pipetted (ml) Phosphorous in standard (mg)
1 0.0 0.000
2 1.0 0.010
3 2.0 0.020
4 4.0 0.040
5 6.0 0.060
6 8.0 0.080
7 10.0 0.100
Each standard was diluted with 10ml of distilled water, then 8ml of hydrazine
sulphate and 2ml of sodium molybdate were added. The resulting mixture was
homogenised and heated in a boiling water bath before cooling and topping up to the
mark and the solution transferred into cuvettes for analysis.
A calibration graph of transmittance against phosphorus content in milligrams was
plotted to compare with the sample aliquots.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
42
ANALYSIS
The percentage transmittance of the sample, blank and standards were measured at
650nm using Cintra 5 UV double-beam spectrometer. The cuvette was thoroughly
rinsed with distilled water between analyses to minimise cross-contamination of
samples. Each sample was analysed in triplicate.
CALCULATION
Phosphorus % = 10 (A-B)
WV
Where:
A = phosphorus content of sample aliquot in mg*
B = phosphorus content of blank aliquot in mg*
W = Weight of sample in grams
V = Volume of aliquot = 10ml
* The phosphorus content of the sample and the blank were read from the
transmittance versus concentration calibration graph.
3.3.3 Physical Properties
3.3.3.1 Moisture and Volatile Matter
(A.O.C.S. Official Method Ca 2b-38)83
PROCEDURE
A 20.0 ±0.5 g sample of homogenized oil was weighed into a beaker then cooled and
dried in a desiccator. The beaker was carefully placed over a hot plate at 80 ºC and
heated with occasional swirling and avoiding splashing. The temperature was slowly
increased to 110 ºC and held at this temperature until the steam disappeared. Then
heated for another 10 minutes before cooling to room temperature in a desiccator. The
Chapter 3 Raw Materials – Feedstock Availability and Analysis
43
sample was weighed and heated over hot plate and cooling was repeated until a
constant weigh was recorded.
CALCULATION
Moisture and volatile Matter % = loss in weight x 100
Weight of sample
Chapter 3 Raw Materials – Feedstock Availability and Analysis
44
3.4 RESULTS AND DISCUSSION
3.4.1 Chemical Analysis of Raw Materials
3.4.1.1 Free Fatty Acid Content.
A large amount of free fatty acid is detrimental to the base-catalytic transesterification
process. Free fatty acid cannot be converted into biodiesel using alkali catalyst, it
reacts with the alkaline catalyst and produces soap that inhibits separation of the
glycerol, biodiesel and water layer before and during purification process. Freedman
et al, 198484, recommends a lipid source with FFA content of less than 0.5% (acid
value of 1) for maximum ester formation via alkali catalytic transesterification. The
results are summarised in Tables 3.8 and 3.9 below.
Table 3.8 Free Fatty Acid Content of Commercial Oil for Biodiesel Synthesis
Range Mean Standard Deviation
FFA (%) AV (mgKOH/g) FFA (%) AV
(mgKOH/g) FFA (%) AV (mgKOH/g)
Soybean Oil 0.1166-0.2141
0.2320-0.4260
0.1538 0.3059 0.0315 0.0626
Canola Oil 0.1558-0.3109
0.3100-0.6184
0.2086 0.4150 0.0496 0.0986
Coconut Oil 3.13-4.33 8.78-12.14 3.72 10.43 0.42 1.18
Table 3.9 Free Fatty Acid Content of Waste Oil for Biodiesel Synthesis
Range Mean Standard Deviation
FFA (%) AV (mgKOH/g) FFA (%) AV
(mgKOH/g) FFA (%) AV (mgKOH/g)
Source 1 1.60-12.85
3.51-28.16 6.75 14.79 4.8580 10.6460
Source 2 5.85-12.09
12.83-26.50
9.56 20.96 2.7942 6.1233
Source 3 0.48-0.95 1.05-2.09 0.75 1.65 0.1910 0.4183
Chapter 3 Raw Materials – Feedstock Availability and Analysis
45
Two commercial oil samples, namely soybean oil and canola oil have FFA value less
than 1% (see Appendix 1 table A1 and A2). However, coconut oil and waste oil (see
Appendix 1 table A3 and A4) contain higher FFA value exceeding 1% or an acid
value of 2. The FFA and Acid value of waste oil have a high standard deviation
indicating the inconsistency in the quality of oil. This amount is considered high and
is seen as a factor that would affect the final yield of biodiesel.
3.4.1.2 Iodine Value
The density and cetane number of fatty acid esters increase linearly with the iodine
number. Whereas, reducing the iodine value is reported to lead to a reduction in NOx
emissions from biodiesel in diesel engines. Biodiesel with an iodine value of 95 has
been demonstrated to emit NOx gases equivalent to certification fuel mean for
petrodiesel (4.59 g/BHP-hr for NOx)85.
Iodine value is inversely related to the storage capacity of the oil. It is the measure of
the unsaturation of fats and oils and is expressed in terms of the number of centigrams
of iodine absorbed per gram of oil (% iodine absorbed). The lower the iodine value
the longer the time it will take for the oil to oxidise under air. That is, low iodine
value oils can be stored for a longer period of time as compared to oil with high
iodine value. The iodine value of a triglyceride is expected to be be very close to that
of the transesterified product since the process does not destroy the double bond in the
fatty acid chain.
The measured iodine values are given in Appendix 1, Tables A5-A8. The results are
summarised in Tables 3.10 and 3.11
Chapter 3 Raw Materials – Feedstock Availability and Analysis
46
Table 3.10 Iodine values of commercial oil samples
Range Mean Standard Deviation
Soybean Oil 116.70-134.47 128.40 5.19
Canola Oil 111.02-132.92 119.97 6.55
Coconut Oil 6.08-9.26 7.91 0.83
Table 3.11 Iodine values of waste oil samples
Range Mean Standard Deviation
Source 1 46.20-51.47 49.27 1.85
Source 2 39.31-64.82 55.42 1.85
Source 3 40.90-70.03 58.81 10.58
3.4.1.3 Phosphorous content.
Phosphorous compounds are present in oil samples as phosphatides. These
compounds are known to be responsible for “gumminess” of oil. Phosphatides present
in biodiesel fuel promote accumulation of water that degrades its quality. Moreover,
phosphorous compounds in oil react with alkali catalysts to cause a reduction in the
final biodiesel yield84.
Chapter 3 Raw Materials – Feedstock Availability and Analysis
47
Figure 3.3 Calibration Graph of Phosphorous Standards
The graph in figure 3.3 was used to determine the:
A- phosphorous content of sample in aliquot (mg)
B- phosphorous content of blank (mg)
Table 3.12 Phosphorous content of commercial oil samples
Range % Mean Standard Deviation
Soybean Oil 0.0003-0.0277 0.0185 0.0131
Canola Oil 0.0001-0.0276 0.0139 0.0140
Coconut oil
Phosphorus content of coconut oil was very low and below significant range and
phosphorous was not detected using this method.
Waste oil
Phosphorus content of waste oil from all three sources was very low and below
significant range and was not detected using this method.
y = -1187.4x + 98.597
R2 = 0.9938
86.00
88.00
90.00
92.00
94.00
96.00
98.00
100.00
0.000 0.002 0.004 0.006 0.008 0.010 0.012
concentration of samples (mg/l)
Tra
nsm
ittan
ce (
%)
Chapter 3 Raw Materials – Feedstock Availability and Analysis
48
The phosphorous content of the commercial oil and waste oil were all very low and
insignificant as they have been degummed during refining process and degraded due
to the heat required for cooking. Thus, the phosphorous content in these oils will not
significantly affect the final biodiesel yield.
3.4.2 Physical Analysis of Raw Materials
3.4.2.1 Moisture content
(A.O.C.S. Official Method Ca 2b-38)80
For biodiesel production the raw material needs have minimal moisture content as
moisture causes soap production during the process.
Table 3.13 Moisture Content and Volatile Matter of Commercial Oil Samples
Range % Mean Standard Deviation
Soybean Oil 0.0179- 0.0862 0.0575 0.0127
Canola Oil 0.0464-0.0837 0.0551 0.0092
Coconut Oil 0.1223-0.4190 0.2854 0.0715
Table 3.14 Moisture Content and Volatile Matter of Waste Oil Samples
Range % Mean Standard Deviation
Source 1 0.0808-0.3785 0.1562 0.0887
Source 2 0.1416-0.2472 0.1925 0.0377
Source 3 0.1416-0.2472 0.1925 0.0377
The moisture content and volatile matter for all the lipid source (commercial and
waste oil) are comparatively below 1%. The amounts are present in a very low
Chapter 3 Raw Materials – Feedstock Availability and Analysis
49
quantity thus saponification during transesterification process due to moisture content
from oil will be low.
3.4.3 Raw Material Used in this Research: Logistics Study
The most significant factors affecting economic feasibility of a continuous biodiesel
production process are the plant capacity and prices of feedstock and biodiesel62. The
starting materials for biodiesel production are the alcohol, the catalyst and the lipid
feedstock. The Pacific region contains developing countries and has limited access to
technological advancement in the chemical reaction field. Thus, the choice of catalyst
and alcohol in the process of transesterification to produce biodiesel fuel will be
mainly determined by what is the cheapest and most readily available. This includes
potassium hydroxide and sodium hydroxide as potential base catalyst used. These
chemicals have wide use for agrochemical and cleaning purposes and are readily
available in local chemical agencies in the regions. Sulfuric acid might be used as an
acid catalyst because it is cheap and readily available.
As far as alcohol is concerned, methanol and ethanol are used in this study. Alcohol is
shipped into the region mainly from Australian chemical companies. Countries like
Fiji Island in the region have great potential to generated ethanol from sugar cane
industry. Fiji Sugar Cooperation are planning to or are researching on expanding and
venturing into ethanol production from baggase (a by product of sugar processing).
Other agricultural biomasses, with high starch content that are available include
cassava and dalo. There is limited range available in selecting the most feasible
catalyst and alcohol as raw material for biodiesel fuel production. In contrast, a
Chapter 3 Raw Materials – Feedstock Availability and Analysis
50
variety of lipid feedstocks are widely available consisting of different vegetable oils
both fresh and used oil.
3.4.3.1 Lipid Raw Material
Lipid sources from various origins are available in Fiji. The following criteria were
used to choose the lipid raw material for biodiesel production. The lipid source must
be:
1. in abundance and accessible,
2. affordable,
3. in consistent supply.
The scope was to cover all possible major lipid sources that were available in
abundance in Fiji. The two possible lipid sources that were explored were commercial
oil and waste oil.
Commercial oil
Vegetable oil is imported into the country and sold for cooking ingredients. The
refined edible oils include soybean oil, canola oil, sunflower oil and olive oil. Coconut
oil was considered suitable for biodiesel production in accordance with the criteria
described above. It is used in biodiesel production trials in the next chapter.
COCONUT OIL
Being a local product, coconut oil is the potential target as a main lipid source since it
abundant and in secure supply. There are coconut industry in Fiji comes under the
control of the Coconut Industries Development Authority (CIDA). Their Savusavu
Coconut mill produces most of the coconut oil and its products, in Fiji. As a lipid
Chapter 3 Raw Materials – Feedstock Availability and Analysis
51
source, it would contribute to reducing the cost of the lipid derivative ascertained as
the final product in biodiesel production.
SOYBEAN AND CANOLA OIL
Around the world the most common feedstock for biodiesel production are canola
(rapeseed) and soybean oil. In this research, soybean oil and canola oil have been used
as lipid source for reference purposes and to compare the result of analytical analysis
of lipids used.
Waste oil
Used oil from restaurants and fast food industries is an attractive feedstock for
biodiesel production. It can simply be collected and used instead of disposing of it as
waste. While unsuitable for re-use in food, used frying oil is the cheapest raw material
for biodiesel production. It contains very similar lipid constituents as non-used oil,
together with the lipids extracted from the food that is cooked in it making it rather
high in free fatty acids. Though not as abundant in supply as coconut oil, waste oil is a
viable lipid source for biodiesel production in Fiji as it is accessible and affordable.
Biodiesel production using waste oil is discussed in the following chapter.
Chapter 4 Synthesis and Purification
52
4 CHAPTER 4 SYNTHESIS AND PURIFICATION
4.1 INTRODUCTION
Biodiesel can be synthesized through acid-, base- or enzyme-catalyzed
transesterification reaction. Transesterification of lipids produces a mixture of fatty
acid alkyl esters (biodiesel) and glycerol as the by-product. It is a set of three
consecutive reversible reactions where diglycerides and monoglycerides are formed
as intermediates as shown in figure 4.186.
Figure 4.1 Transesterification of triglycerides - Three-step consecutive reactions
Several factors affect the transesterification reaction. These include the molar ratios of
products, type of catalyst, free fatty acid (FFA) content of the lipid raw material, time
of reaction and temperature at which reaction occurs. The molar ratio of triglyceride
and alcohol is 1:3, however excess alcohol is used to increase the yield of fatty acid
alkyl ester and allow its phase separation from the glycerol formed.
TG + DG + R1COOCH3
DG MG R2COOCH3
MG GL R3COOCH3
+ +
+ +Overall reaction
TG GL 3RCOOCH3
CH3OH
CH3OH
CH3OH
+ 3CH3OH +
Where: TG : triglyceride
DG : Diglyceride
MG : Monoglyceride
Chapter 4 Synthesis and Purification
53
The recovery of by-product glycerol and the excess alcohol from the final crude
mixture is incorporated as an essential step in commercial production of biodiesel fuel.
Returns from the by-product and recycling raw materials reduce the final cost of
production of biodiesel. Extracted and purified glycerol is used in food,
pharmaceutical and cosmetic industries.
Phase separation and purification of the product is also significantly important to the
final yield of biodiesel produced.
Acid Catalyzed Reaction
This is more suited for transesterification of lipid raw materials with high free fatty
acids as it also esterifies the fatty acid in the fats or oil. Acid-catalyzed reaction
enables production of long- and branched-chain esters that are difficult using alkaline
catalysts. However, when acid catalyst is used in high reaction temperatures it
promotes formation of unwanted secondary products such as dialkyl ether and
glycerol ethers.
Presence of any water in the (raw material or resulting from the reaction) is
detrimental to acid-catalyzed transesterification reaction. Esterification of FFA
produces water and this inhibits further reaction resulting in low conversion into alkyl
esters. Figure 4.2 illustrates the mechanism of acid transesterification reaction.
Chapter 4 Synthesis and Purification
54
Figure 4.2 Mechanism of Acid Catalysed Transesterification of Lipids.
Acid transesterification of lipids starts with (1) protonation of the carbonyl group by the
acid catalyst; (2) nucleophilic attack of the alcohol, forming a tetrahedral intermediate
after which the (3) proton migration and breakdown of the intermediate step continues.
The sequence (1-3) is repeated twice in case of a triglyceride as shown.
Base Catalyzed Reaction
Alkaline catalysts have a lot of advantages over other catalysts. It is more economical
and effective than acid catalysts as reaction proceeds faster and to completion more
quickly with higher yields in absence of water. This type of catalyst is less corrosive
and safer to handle which is why they are most favourably used for biodiesel
synthesis. See figure 4.3 for mechanism of base catalyzed transesterification.
CH CH2
H2C
OR"COO
OOCR'
C
O
R'" CH CH2
H2C
OR"COO
OOCR'
C
OH+
R'"H
+ (1)
CH CH2
H2C
OR"COO
OOCR'
C
OH+
R'" + R4OH
CH CH2
H2C
OR"COO
OOCR'
R'"O
+
H
R4
OH
(2)
CH CH2
H2C
OR"COO
OOCR'
R'"O
+
H
R4
OH
CH CH2
H2C
OHR"COO
OOCR'
+ O
R'''
OR4
+ H+ (3)
Chapter 4 Synthesis and Purification
55
Figure 4.3 Mechanism of Base Catalysed Transesterification of Lipids87
(1) Reaction of base with the alcohol, producing the alkoxide and the protonated
catalyst. (2) The nucleophilic alkoxide ion attacks at the carbonyl group of the
triglyceride generating a tetrahedral intermediate, which, in step (3), fragments to
release the alkyl ester (ROOCR”) and the corresponding anion of the diglyceride. In
step (4), the diglyceride anion is protonated regenerating the catalyst (B) for another
catalytic cycle. Diglycerides and monoglycerides are likewise converted by the same
mechanism to a mixture of alkyl esters and glycerol.
Other Production Processes
The use of raw material with different properties has already been explored in the
transesterification process. Examples include using homogenous, heterogenous and
enzymatic catalysts and supercritical methanol (chapter 3).
ROH + B RO- + BH
+
CH CH2
H2C
OR"COO
OOCR'
C
O
R'"+
CH CH2
H2C
OR"COO
OOCR'
C
O-
OR
R'"
CH CH2
H2C
OR"COO
OOCR'
C
O-
OR
R'"CH CH2
H2C O-
R"COO
OOCR'
+ ROOCR"'
CH CH2
H2C O-
R"COO
OOCR'
+ BH+
CH CH2
H2C OH
R"COO
OOCR'
+ B
(1)
(2)
(3)
(4)
-OR
Chapter 4 Synthesis and Purification
56
For good ester conversion via alkaline transesterification reaction, the low-grade
(containing high Free Fatty Acid or FFA content) lipid raw materials are pretreated
(hydrolysed) to reduce the content of free fatty acids. A simple two-step acid
catalyzed pretreatment process, reduced the acid values of lipid feed stock, namely,
yellow grease (acid value of 18.03mg KOH/g) and brown grease (acid value of
79.20mg KOH/g) to less than 2mg KOH/g35 (1) FFA reacts with alkali catalysts
forming undesirable by-products (soap and water). (2) Water deactivates the catalyst
that aids in soap formation. Thus the cycle continues eventually inhibiting (slowing
down) ester formation. Figure 4.4 describes this.
R
O
OH
+ NaOH ( or MeONa)
R
O
O-Na
+
+ H2O ( or MeOH)
Soap
R
O
OMe
+ H2O Base Catalyst
R
O
OH
+ MeOH
(1)
(2)
Figure 4.4 Soap formation due to high FFA and deactivation of catalyst during Base
catalysed transesterification process
Product Purification
After phase separation of the reaction mixture the product needs to be purified to
achieve maximum ester yield and optimum quality biodiesel. Excess methanol can be
removed by heating the ester layer, however this is not economical for commercial
production thus a much easier and safer alternative is to wash it with water. Saline
water can be used for easy separation. Washing also removes traces of glycerol. Most
glycerol gets separated out in the separation phase, however it can also be removed by
Chapter 4 Synthesis and Purification
57
converting it into FFA by adding alkaline catalyst. Acidified water is recommended
for this, which also clears out catalyst and alcohol residues. Acid washing requires
special equipment to facilitate safe purification process and adds on to the production
cost. Another way of purifying ester from FFA is by distillation (esters have lower
boiling point then its FFA).
This chapter investigates the synthetic methods and purification process of methyl and
ethyl esters (biodiesel). The locally available raw materials identified in pervious
chapter are used. The effect of parameters affecting tranesterification like high FFA
and water content of lipid raw material are reduce or eliminate by introducing
pretreatment processes. Optimization of pretreatment and transesterification process
are carried out to produce quality biodiesel. The effect of catalyst and alcohol is also
investigated together with different purification methodologies of crude biodiesel.
The quality of biodiesel is later determined using gas chromatography (GC) and gel
permeation chromatography (GPC) (Chapter 5).
Chapter 4 Synthesis and Purification
58
4.2 METHODOLOGY
4.2.1 Synthesis Process
The methods investigated for making biodiesel from various oils and alcohol are
categorized in the Venn diagram illustrated in figure 4.5.
Figure 4.5 Successful ester (biodiesel) synthetic methodologies.
A is the set of successful methodologies (acid or base catalyzed and one step or two step) used
for the synthesis of biodiesel (methyl or ethyl esters) from different lipid sources as described
in the text.
Method 1 – Acid pretreatment, one step base catalyzed transesterification,
Method 2A – One step base transesterification,
Method 2B – Two step base transesterifcation and
Method 3 – Base neutralization, one step base transesterification.
In chapter 3, it was found that some of the lipid raw materials contained too much
FFA (i.e., > 1.0%) or moisture content (>1.00% by weight of sample) for efficient
Coconut Oil Methyl Ester
Waste Oil
Methyl Ester
Coconut Oil Ethyl Ester
Waste Oil Ethyl
Ester
Soybean Oil Methyl Ester
Canola Oil Methyl Ester
Coconut Oil Methyl Ester
Coconut Oil Ethyl Ester
1
3
2A
2B A
Chapter 4 Synthesis and Purification
59
base-catalysed transesterification. The following actions were taken to make the raw
materials more suitable:
Table 4.1 Treatment of lipid raw materials undertaken prior to
transesterification reactions to produce biodiesel
Existing Unsuitable variables Solution/ treatment
High FFA% content of lipids • Acid pretreatment (method 1) process where the FFA is esterified.
• Base neutralisation (method 3), where excess base catalyst destroys FFA and transesterification of triglycerides is completed with catalyst amount of 1% by weight of oil.
High moisture content • Oil samples were heated over hotplates at 70ºC for 5-6 hours with constant stirring. This method was developed to ensure that the FFA% content remained same after dehydration process.
The flowchart illustrated below describes the fate of lipid raw material in the biodiesel
synthetic process. Determination of free fatty acid (FFA) content of oil (Chapter 3) is
an essential quality control measure that needs to be known prior to transesterification
reaction.
Figure 4.6 Fate of Lipid Feedstock Depending of their Free Fatty Acid Content.
Lipid Feedstock
Pretreatment: 1) Acid Catalyzed 2) Base Neutralised
Transesterification Using Base catalyst in
alcohol (methanol/ethanol)
FFA >1%
FFA>1%
Chapter 4 Synthesis and Purification
60
4.2.1.1 Method 1 Acid pretreatment, one-step base-catalysed transesterification
This method is used for lipid raw materials with high FFA content (>1.00% FFA or
acid value >2.00 mg KOH/g)88. These include only coconut and waste oils in this
research. All samples were pre-dried using the method in Table 4.1.
Figure 4.7 Flowchart Illustrating Procedure for Method 1
PR
ETR
EA
TM
EN
T
BA
SE
TR
AN
SE
STE
RFIC
ATIO
N
PU
RIF
ICA
TIO
N
Sulphuric acid +
Alcohol +
Oil with FFA% >1%
Pretreated Oil
Alcohol Layer
1
2
3
45 6
7
8
9
1 10
2
3
45 6
7
8
9
11
Oil + Acid + Alcohol
1
2
3
45 6
7
8
9
1 10
2
3
45 6
7
8
9
11
Stirrer
Base
catalyst +
Alcohol Pretreated oil + Base catalyst +
Alcohol
BIODIESEL
Wash water
Wash water (distilled or saline
water)
Chapter 4 Synthesis and Purification
61
PROCEDURE
Acid Pretreatment
To 200 ± 1g of coconut oil (FFA as lauric acid 3.52% as per analysis method of
chapter 3) in a round bottom flask was heated to 60 ºC and to this was added a
warmed (60 ºC) solution of concentrated sulfuric acid (0.4ml, representing 0.1g
H2SO4 per 1.0g FFA) in methanol (28.5ml representing 20 mole methanol per mole of
FFA, formally lauric acid Mr = 200g/mol)and the resulting mixture heated to reflux
with magnetic stirring for 1.5 hours before being transferred to a separating funnel,
cooled and separated. The triglyceride (lower) layer was washed three times with
10ml portions of methanol to remove the acid catalyst and water of reaction. The
exact quantities of ingredients used are given in the Appendix Table A15.
The FFA content of the pretreated oil (see Appendix Table A.16) was determined
using A.O.C.S official tentative method Ca 5a-40. If the FFA content was <1.00 % or
2.00 mg KOH/g then it was transesterified using one step base transesterification
process as described below. However, if this was not the case, further pretreatment
process was carried out in a similar manner as described, but this time with a 40:1
molar ratio of triglycerides to methanol. This followed a washing process with
absolute methanol and the FFA content was measured. Washed pretreated lipid layer
was then transesterified according to one step base transesterification process.
The FFA content of all oil samples pretreated in this experiment reduces to < 1% after
treatments.
Chapter 4 Synthesis and Purification
62
Note that the method explained is based on coconut oil as lipid raw material; waste oil
was also used to prepare methyl esters using this method.
CALCULATION
Amount of catalyst- sulphuric acid (ml)
Where:
1.8 g/moles is the density of absolute methanol
M (H2SO4) is the mass of sulphuric acid and is calculated using the following
equation;
Where:
M (FFA) is the mass of FFA in oil raw material weighed out and is calculated
using the following equation;
Where:
M (oil) is the mass of oil sample (g)
FFA% is the amount of FFA% of the oil sample obtained by A.O.C.S official
tentative method Ca 5a-40.
Volume of sulphuric acid = molesg
M SOH
/8.1)( 42
)()(10010
42 FFASOH MM ×=
)()(100
%oilFFA M
FFAM ×=
Chapter 4 Synthesis and Purification
63
Volume of methanol
Where:
0.791 g/moles is the density of absolute methanol
M (MeoH) is the mass of absolute methanol and is calculated using the
following equation;
* used 40 when calculating methanol volume for the second pretreatment process.
Where:
M (FFA) is the mass of FFA in oil raw material weighed out
Mr ( FFA) is the molecular weight of free fatty acid being analysed. Lauric
Acid in this case
Mr ( MeOH) is the molecular weight of methanol
Constant 20 is the molar ratio of triglyceride/methanol in the first
pretreatment process.
Base Transesterification of Pretreated Oil (One Step)
PROCEDURE
Sodium methoxide, the base catalyst for transesterification was prepared by
dissolving sodium hydroxide (analytical grade) in absolute methanol. The amount of
sodium hydroxide (1.09g) was calculated base on the amount required to neutralize
Volume of methanol =molesg
M MeOH
/791.0)(
)()(
)()( *20 MeOH
FFA
FFAMeOH Mr
Mr
MM ××=
Chapter 4 Synthesis and Purification
64
the FFA content of the pretreated lipid (FFA%, 0.49% or acid value, 1.38 mg KOH/g)
plus 1% of the unreacted oil mass. The volume of absolute methanol (38.2 ml) was
calculated based on the molar ratio of oil/absolute methanol which was 1:6. Sodium
hydroxide was then swirled at room temperature to dissolve in alcohol to make an
alkoxide catalyst (see Appendix Table A.17)
In a typical reaction, 100.5g of the oil was heated to 60 °C in a round-bottom flask
that was loosely stoppered to avoid introduction of moisture, which can destroy
catalyst and result in undesirable by-products such as soap. A preheated (60 °C)
solution of catalyst in methanol (prepared as above) was rapidly added to this through
a funnel and the resulting mixture was magnetically stirred and heated to boiling
under a reflux condenser. After two hours of boiling with magnetic stirring, the
reaction mixture was transfered to a separating funnel and allowed to cool to room
temperature. The lower glycerolic layer was removed and the upper ester layer (crude
biodiesel) was purified as described below (see 4.2.2 Purification).
Where ethanol was used instead of methanol the preheating temperature was
increased to 75 °C (just below the alcohol's boiling point).
CALCULATION
Amount of Catalyst
Where,
M (p. oil) is the mass of pretreated oil
Mass of catalyst to neutralize acid 4056
1
1000
)( ×××= ValueAcidM oilpretreated
Chapter 4 Synthesis and Purification
65
Acid Value (mg KOH/g) is obtained by AOCS official tentative method Ca 5a-40.
Constant 40 is the molecular weight of sodium hydroxide
Constant 56 is the molecular weight of potassium hydroxide
Amount of methanol
Where:
0.791 g/moles is the density of absolute methanol
M (MeoH) is the mass of absolute methanol and is calculated using the
following equation;
Where,
M (p. oil) is the mass of pretreated oil
Constant 6 is the molar ratio of excess amount of methanol
Constant 32 is the molecular weight of methanol
Mr( triglyceride) is the molecular weight of the triglyceride. Use the following molecular
weight of triglyceride when using the respective pretreated oil:
Volume of methanol =molesg
M MeOH
/791.0)(
326)()(
)( ××=detriglyceri
oilpretreated
Mr
MMeOHM
Chapter 4 Synthesis and Purification
66
Table 4.2 Molecular weights of Triglycerides in Lipid Raw Material.
Triglyceride Molecular weight (g/moles) Oil*
Trilauryl glycerol 639.00 Coconut oil
Trioleoyl glycerol 885.43 Soybean oil
Canola oil
Tripalmitoyl glycerol 806.74 Waste oil- source 1
Trioleoyl glycerol 885.43 Waste oil- source 2
- source 3
* Same molecular weights are used for calculation in preteated oil.
4.2.1.2 Method 2A - One Step Base Transesterification (No pretreatment)
This method is employed to produce methyl and ethyl esters from lipid source with
FFA content <1.00% or acid value <2.00 mgKOH/g. The oils used in this method
included canola oil, soybean oil, two samples of waste oil (FFA% was <1.00%), and
coconut oil which was used as comparison purposes.
This method was used to explore the variables affecting transesterification to produce
esters and their purification. These variables include:
Type of catalyst: sodium hydroxide versus potassium hydroxide
Types of alcohol: methanol versus ethanol
Chapter 4 Synthesis and Purification
67
Figure 4.8 Flowchart Illustrating Procedure for Synthetic Method 2A
PROCEDURE
The catalyst was prepared by dissolving the alkali (NaOH or KOH) in the alcohol
(methanol or ethanol) at room temperature taking care to avoid the introduction of
moisture.
BA
SE
TR
AN
SE
ST
ER
FIC
AT
ION
P
UR
IFIC
AT
ION
1
2
3
45 6
7
8
9
1 10
2
3
45 6
7
8
9
11
Base
catalyst +
Alcohol Lipid (oil) +
Base catalyst + Alcohol
BIODIESEL
Wash water
Wash water (distilled or saline
water)
Chapter 4 Synthesis and Purification
68
In a typical reaction, 200.0g of soybean oil was heated in a loosely stoppered round-
bottomed flask to 60 °C in a water-bath and to this was added (rapidly through a
funnel) a preheated (60 °C) solution of KOH (2.00g or 1.0% of the oil mass) in
methanol (55.11 mL, for a 6:1 methanol/triglyceride ratio). The resulting
heterogeneous mixture was magnetically stirred and heated to boiling under a reflux
condenser for 1.5 hours. The mixture was transferred to a separating funnel and
allowed to cool. The lower glycerolic layer was removed and the upper ester layer
(crude biodiesel) was purified as described below (see 4.2.2 Purification).
CALCULATION
Amount of Catalyst
Where,
M (oil) is the mass of oil
Amount of methanol
Where:
0.791 g/moles is the density of absolute methanol
M (MeoH) is the mass of absolute methanol and is calculated using the
following equation;
Where,
Mass of catalyst = 1001
)( ×oilM
Volume of methanol = molesg
M MeOH
/791.0
)(
M (MeOH) = 326)(
)()( ××=
detriglyceri
OilMeOH Mr
MM
Chapter 4 Synthesis and Purification
69
M (oil) is the mass of oil
Constant 6 is the molar ratio of excess amount of methanol
Constant 32 is the molecular weight of methanol
Mr( triglyceride) is the molecular weight of the triglyceride. Use the following molecular
weight of triglyceride when using the respective pretreated oil:
Chapter 4 Synthesis and Purification
70
4.2.1.3 Method 2B – Two-Step Base Transesterification (No pretreatment)
Figure 4.9 Flowchart Illustrating Synthetic Procedure for Method 2B
PROCEDURE
The two-step procedure 2B in the same as procedure 2A except that only 75% of the
catalyst mixture is added in the first step. The mixture was heated to reflux for 1.5
hours, transferred to a separating funnel, allowed to cool and the glycerolic layer
removed. The upper layer was transferred back to the round-bottom flask and the
remaining 25% of catalyst mixture was then added and the resulting mixture heated
under reflux with magnetic stirring for a further 1.0 hours. The reaction mixture was
finally transferred to a separating funnel, allowed to cool and the upper ester layer
(crude biodiesel) purified as described below (see 4.2.2 Purification).
BA
SE
TR
AN
SE
ST
ER
FIC
AT
ION
P
UR
IFIC
AT
ION
1
2
3
45 6
7
8
9
1 10
2
3
45 6
7
8
9
11
Base
catalyst +
Alcohol
Lipid (oil) + Base catalyst +
Alcohol
BIODIESEL
Wash water
Wash water (distilled or saline
water)
¾ of the mixture is added at the beginning of reaction and ¼ after an hour.
Chapter 4 Synthesis and Purification
71
Note: In some cases, no separation occurred, and the remaining catalyst mixture was
still added to complete transesterification process.
4.2.1.4 Method 3 Base Neutralisation, One Step Base Transesterification
This method was used for preparing ethyl esters from oil containing high FFA
(>1.00% or acid value of 2.00mgKOH/g). Coconut oil and waste oil both have high
FFA and used as lipid sources for this method.
Figure 4.10 Flowchart Illustrating Synthetic Procedure for Method 3
BA
SE
TR
AN
SE
ST
ER
FIC
AT
ION
P
UR
IFIC
AT
ION
1
2
3
45 6
7
8
9
1 10
2
3
45 6
7
8
9
11
Lipid (oil) + Base catalyst +
Alcohol
BIODIESEL
Wash water
Wash water (distilled or saline
water)
Base catalyst (MOLAR EXCESS)
+ Alcohol
Chapter 4 Synthesis and Purification
72
PROCEDURE
Potassium hydroxide (1.36g) was used as catalyst for ethanolysis reaction. The
amount was calculated based on the FFA amount in the feedstock i.e. the amount of
catalyst required to neutralize the FFA in oil plus 1% of the oil sample. A 6: 1 molar
ratio of ethanol: triglyceride was used. See Appendix, tables A.26 and A.27. The
catalyst mixture preparation and transesterfication process was same as the steps
described in method 2A. The preheating and reaction temperature was 75ºC if ethanol
was used.
4.2.2 Purification
Purification process involved washing of ester layer collected after transesterification
to remove water-soluble contaminants like unreacted catalyst and alcohol. The use of
saline water was explored as an effective washing agent relative to distilled water at
room temperature. Saline water is readily available in the Pacific region and could be
utilized for washing process reducing the cost factor of production.
PROCEDURE
Comparison between using distilled water and saline water washing was made. The
washing technique was also tried which included spraying water with:
1. garden spray (fine nozzle);
2. wash bottle (direct and strong dispersion); and
3. adding an equal volume of water and shaking in a separating funnel (agitation)
Chapter 4 Synthesis and Purification
73
The best washing technique was determined based on the time required for the ester
layer and wash water layer to separate. The visual clarity of the wash water layer was
also compared with other wash water layer from esters prepared using the same
method. The best washing technique was then employed to purify all subsequent
biodiesel samples.
Distilled water washing
25-50ml of crude ester layer was taken in a separating funnel and washed (sprayed)
with distilled water. After each washing process the mixture was allowed to separate
for 12 hours before any observations were made. The lower layer (water and water
solubles) was discarded and the upper layer (containing esters) was washed with the
next portion of water. Each sample was washed three times with equal amount of
water adding up to 3 times more water as the sample.
Saline water washing
Moderate saline water (3.5g of NaCl in 1liter of distilled water) was prepared to
depict the seawater. This was then sprayed on to 25-50 ml of crude ester sample in a
separating funnel and left to settle for 12 hours. The lower layer (water and water
solubles) was discarded and the upper layer (containing esters) was washed with the
next portion of water. The samples were washed with equal portions of saltwater
amounting to 3 times more than the sample volume. After the third washing similar
washing process was continued with distilled water to remove the salinity introduced
via salt water cleansing.
Chapter 4 Synthesis and Purification
74
Infra red (IR) analysis
After washing process IR analysis of each sample was carried out to ensure that
alcohol and water was not present in the samples. This was done using Perkin Elmer
FT-IR spectrometer spectum 1000 instrument using winlab software.
Samples were prepared for analysis by placing a drop of sample between two cleaned
and dried sodium chloride discs. The percentage transmittance (T%) was obtained by
scanning between 400-4000 cm1− wavelengths.
Chapter 4 Synthesis and Purification
75
4.3 RESULTS AND DISCUSSION
4.3.1 Method Optimization
Type of catalyst
Potassium hydroxide and sodium hydroxide were investigated as basic catalyst for
transesterifcation reaction to produce biodiesel.
Sodium hydroxide dissolved in ethanol
results in a semi solid solution after
some time. When this is heated and
added to preheated (75 ºC) coconut oil
it forms a jelly solution. This causes
difficulty in stirring the mixture during
Figure 4.11 Miscibility Problems during Synthesis of Biodiesel
transesterification process. Even if the mixture turns into liquid state due to heating
and stirring, it jells back after the mixture is cooled to room temperature which is not
ideal for fuel. The jelling effect of coconut oil is accentuated by high amounts of
FFA% content in the oil89. This was not observed when the catalytic mixture was
added to soybean or canola oil.
Potassium hydroxide was used alternatively to avoid the jellying problem during
ethanolysis reaction. It is compatible with both ethanol and methanol solvents.
Chapter 4 Synthesis and Purification
76
The optimum percentage of each catalyst was determined by observing the amount of
soap (off white layer that floats on water layer, just below ester layer) produced and
the amount of water required to completely clean the crude biodiesel.
Table 4.3 Trial for suitable catalyst for transesterification reaction and its
observation
Trials Observations Methanolysis
1% NaOH with oils containing low FFA% (<1.00%)
- catalyst easily miscible with methanol during catalyst preparation - no soap produced - good separation of wash water and lipid layer.
1% NaOH with oils containing high FFA% (>1.00%)
- Observations were similar to reaction with low FFA% oil but soap was produced in this case and required several washing before it cleared out.
Ethanolysis 1% and 0.5% NaOH with oils containing low FFA%
- catalyst forms jell after some time with ethanol during catalyst preparation
- no soap produced - good separation of wash water and lipid layer.
1% NaOH with oils containing high FFA%
- catalyst forms jell after some time with ethanol during catalyst preparation
- soap produced that requires several (8-10 times with equal amount of water as the ester layer, each time) washing with water.
- No good separation of wash water and lipid layer as heaps of soap is produced.
0.5% NaOH with oils containing high FFA%
- catalyst forms jell after some time with ethanol during catalyst preparation
- less soap produced that requires bit less (5-7 times with equal amount of water as the ester layer, each time)washing with water to clear out.
- No good separation of wash water and lipid layer as heaps of - soap is produced.
1% KOH with oils containing high FFA%
- catalyst is miscible with ethanol during catalyst preparation - soap produced that requires several (8-10 times with equal amount of
water as the ester layer, each time) washing with water. - No good separation of wash water and lipid layer as heaps of soap is
produced. 0.5% NaOH with oils containing high FFA%
- catalyst is miscible with ethanol during catalyst preparation - less soap produced that requires bit less (5-7 times with equal amount
of water as the ester layer, each time)washing with water to clear out. - No good separation of wash water and lipid layer as heaps of soap is
produced.
Chapter 4 Synthesis and Purification
77
Pretreatment trials (Method 1)
The purpose of pretreatment is to reduce the FFA % content of lipid raw material
containing high FFA% to meet the prerequisites for base transesterification i.e. FFA%
should be < 1.00%.
The molar ratio of alcohol/FFA and the catalyst content was explored in order to
determine the best system of pretreatment. The experimental trials carried out are
summarized in Table 4.4 below.
Table 4.4 Optimizing Pretreatment Coconut Oil Using Acid Catalyst and
Methanol.
Molar excess of methanol to FFA 20:1
Catalyst amount 10% (a) Catalyst amount 5% (a)
1 2 3 1 2 3
FFA % before pretreatment
3.58 3.52 3.52 3.92 4.03 4.11
FFA% after pretreatment
0.52 0.53 0.78 1.14 1.55 1.63
Ratio of FFA% reduced(b)
6.07 6.64 4.5 3.44 2.60 2.52
(a) acid catalyst – sulfuric acid, amount calculated based on mass of coconut oil.
(b) calculated for comparison purposes: (FFA% before pretreatment/FFA% after pretreatment)
From the pretreatment trial it can be observed that the ration of FFA% reduced is
greater when a molar ratio of 20:1 (methanol/FFA) is used with 10% catalyst
(calculated based on mass of oil). This combination effectively reduces the FFA% to
the required level as suggested by Canakci. M et al, 200188. However, Canakci’s
study was carried out using lipid raw material with higher FFA% as compared to this
research, thus the 5% catalytic content was considered to be investigated. Kinetic
Chapter 4 Synthesis and Purification
78
studies on esterification of FFA with methanol in presence of sulphuric acid proves
that much higher molar ratios alcohol can be used achieve similar results in less time90.
This method could not be used to produce ethyl esters as the ethanol and lipid layers
could not be separated after acid pretreatment. This is due to the fact that the oil is
more soluble in ethanol than in methanol. Several trials were carried out using ethanol
as alcohol source for pretreatment process but it was observed that the FFA%
decreased very slightly with 20: 1 (ethanol/FFA) molar ratio with both the10% and
5% catalyst content. However, increasing the molar ratio to 40:1 (ethanol/FFA in oil)
it was seen that the hydrolysis of FFA was greater (Table 4.5). Also having a greater
molar ratio induces good separation of the alcohol/water/acid layer from the lipid
layer.
Table 4.5 Optimizing Pretreatment Process of Coconut Oil using Acid Catalyst
and Ethanol.
Excess molar ratio of ethanol/FFA in coconut oil
40:1 20:1
Catalyst amount (a) Catalyst amount (a)
10% 5% 10% 5%
FFA % before pretrteatment
3.92 4.04 3.66 3.92
FFA% after pretreament
1.31 2.36 2.22 2.22
Ratio of FFA% reduced(b)
2.98 1.71 1.64 1.77
(a) acid catalyst – sulfuric acid, amount calculated based on mass of coconut oil.
(b) calculated for comparison purposes: (FFA% before pretreatment/FFA% after pretreatment)
It was also noted that the separation of coconut oil and methanol layer was less
obvious than waste oil and methanol layer during the pretreatment process. The
chemical composition of each oil influences its miscibility with the solvents used.
Coconut oil has a greater composition of average length lipids (C8-C20), whereas
Chapter 4 Synthesis and Purification
79
used oil contains major constituents that are longer chains of fatty acids (> C20) some
of which gets introduced
from the food stuff cooked in it.
Thus from the trial carried out, 20:1 (methanol/FFA) and 10% catalyst is optimum for
pretreatment of an oil under going methanolysis. Using ethanol in a molar excess >
40:1 (ethanol/FFA) for pretreatment of oil undergoing ethanolysis process to produce
ethyl esters (biodiesel).
4.3.2 Observations and results for the methodology used to prepare biodiesel
Acid pretreatment, one-step base transesterification (1)
Methanolysis
The methanol/water/acid layer was evidently separated from the lipid layer after
pretreatment process. After the methanolysis of pretreated oil the glycerol layer and
ester layer were also obviously separated without any intermediate layers (A). The
washing process of ester layer was efficient, as the wash water became clear (B) in a
few washings (3-4 times). However it should be noted that using higher molar ratios
of alcohol limits phase separation of the glycerol and biodiesel layer after
tranesterification.
Chapter 4 Synthesis and Purification
80
Figure 4.12 Treatment of Reaction Mixture to Obtain Purified Biodiesel
A – Showing very distinct separation of the glycerol and crude biodiesel layers. The later is then
purified through washing process. B shows the purified biodiesel sample with excellent clarity after
washing.
Ethanolysis
No ethanolysis was carried out as the ethanol and lipid layer does not separate after
pretreatment process. Attempts were made to remove the ethanol layer using
rotavapour technique or heating but in each case only the ethanol get removed leaving
the water and acid (from acid catalyst, sulphuric acid) content in the solution. This
was known from the FFA% content of the pretreated oil as the FFA% content
increased after treatment and removal of ethanol as compared to the FFA% of the oil.
For commercial production these methods would not be practical as it would add onto
the cost of production and demand more energy input as heating in involved.
One step base transesterification (2A) and two steps base transesterification (2B)
Methanolysis
For all types of oil, methanolysis showed results as predicted. There was homogenous
mixing of catalyst solution (sodium hydroxide and methanol) with oil when added. At
the end of the reaction the glycerol layer and ester layer separated distinctly with no
Crude Biodiesel
Crude Glycerol
A
Biodiesel
Wash Water
B
Chapter 4 Synthesis and Purification
81
intermediate layers thus only the ester layer was introduced to the purification stage.
Soap was produced when washing methyl esters of lipids with high FFA content such
as coconut oil.
Methyl esters from soybean oil and canola oil were
easy to purify as the wash water became clear after
3-4 washings. Once water was sprayed onto the
ester layer the separation of ester and water layer
was separated quickly (10 minutes). With coconut
oil this was not the case (figure 4.13). Several
washings were required (5-8 times) before the
wash water became clear.
Figure 4.13 Soap formation while washing crude biodiesel (methanolysis)
The time for ester layer and water layer to separate after the first few washing took at
most 12 hours. But the layers required less time to separate well in the later washings.
Ethanolysis
It was observed that the glycerol and the ethyl ester did not separate at all for any of
the lipid raw materials explored so far. This is due to the excess ethanol present in the
crude ethyl ester mixture. Thus where 50ml of the crude biodiesel and glycerol layer
was washed with water the glycerol and ester layers separate after a few washings.
This is due to the removal of excess ethanol with wash water in the solution. The
amount of washing and the time required for the wash water and ester layers to
separate were similar to those for methanolysis after that. More washing was required
Chapter 4 Synthesis and Purification
82
for coconut oil than for soybean or canola oil and the time required for the water and
ester layers to separate was slower for coconut oil ethyl esters in its first few washings.
Washings were more easily separable.
Base Neutralisation One-Step Base Transesterification (3)
This method is specifically targeted for the ethanolysis of lipid raw material with high
FFA% content. During and after the reaction process the separation of glycerol and
ester layer is not evident. (Thus, 50ml of the crude biodiesel and glycerol layer is
washed).
The excess base that is used to neutralize the FFA of
lipids also creates problems during the washing process
because it forms soap. For the chemical equation see 4.1.
Introduction. This eventually gets washed out and the
pale biodiesel layer becomes more evident.
Figure 4.14 Excess Soap Formation while Washing Crude Biodiesel (ethanolysis)
Thus, in the purification process of this method there is a lot of soap formation,
though the ester layer can still be purified. This method is not recommended for use
with lipid raw material with very high FFA% as excessive amount of soap will be
formed and the esters formed will be lost during purification process.
Chapter 4 Synthesis and Purification
83
4.3.3 Observations and results for purification process
4.3.3.1 Washing Method optimization
The following methods of water washing were investigated to purify the ester
produced.
Garden spray (fine nozzle)
This was found to be the best way of washing the ester with water. It was observed
that very fine droplets of water dispensed from the nozzle settle in the bottom layer
having passing through the organic layer collecting water-solubles over a larger area.
The wash water became clear after only a few washings and the time required to settle
and separate the water from the ester layer was moderate (4-6hours).
Wash bottle (direct and strong dispersion)
The wash water obtained after using wash bottle for washing was still milky even
after 5-8 washes. This was due to the water being sprouted on only one spot of the
ester layer and washing only that portion. It was observed that the whole layer does
not get washed during washing, as water being dispensed from the wash bottle does
not cover the whole ester layer surface. But the time required for the separation of
ester and water layer was very quick (15-30 min) and no emulsion was formed
between the organic and aqueous layers.
Adding equal amount of water and shaking the separating funnel (agitation)
This was found to be the most unfavourable method as shaking the transesterified
mixture causes an emulsion, which took several hours to separate (sometimes more
Chapter 4 Synthesis and Purification
84
than 12 hours). On the plus side, the wash water was usually clear after a few
washings. In some occasions, however, an intermediate layer was formed which was
difficult to get rid of, even with extended hours of settling.
The percentage of water-soluble products lost during washing process aids in
mapping out the best method for biodiesel synthesis. These products include excess
alcohol, soluble glycerides and soap. It has been observed that loss of ester occurs
when there is great formation of soap as it gets trapped in between and washed away.
Thus it is important to note the percentage of purified biodiesel retrieved after the
washing crude biodiesel. As the molar ratio of the reactants are similar for all methods
investigated comparison can be done. The following formula was used :
Table 4.6 Percentage Loss of water soluble during purification of biodiesel
synthesized using the methods investigated.
Samples Method of
Synthesis
Range (%) Median (%)
Coconut Oil Methyl Esters 1 12.10-20.56 16.44
2A 15.72-24.07 19.32
2B 15.40-27.76 19.57
Coconut Oil Ethyl Esters 2A 38.108-55.05 44.21
2B 33.90-66.21 43.05
3 55.15-74.83 61.66
Waste Oil Methyl Esters 1 16.22-25.33 18.61
Waste Oil Ethyl Esters 3 75.64-89.91 85.71
Comparing the results (medians) relative to the method of synthesis used it can be
seen that there is less % loss of water solubles in methanolysis than ethanolysis.
% Loss of water-soluble = (Mass of crude Biodiesel - Mass of washed Biodiesel) x 100 Mass of crude Biodiesel
Chapter 4 Synthesis and Purification
85
Method 3 is not an efficient method as more than 50% of the crude product is lost
before biodiesel purifies, with 61.66% and 85.71% lost in washing. Note that the
decision that the product is purified is based on the clarity of the washed biodiesel.
Methods 2A and 2B are more effective for methanolysis (19.32% and 19.57%
respectively) of coconut oil than ethanolysis (44.21% and 43.05%). Out of all the
methods investigated for methanolysis of vegatable oil, method 1 was the best with %
loss of water solubles as 18.61% and 16.44% for waste oil and coconut oil,
respectively.
4.3.3.2 Comparison of washing processes using distilled water and saline water
Saline water
Use of saline water during washing is appropriate when there is soap formation in the
mixture after transesterification. It has a salting out effect that makes it easier for the
soap to fall out of solution and form a distinct layer between the ester and water layers.
This way removal of soap from the solution becomes more efficient than using
distilled water. One of the drawbacks of this wash water is that the salinity
accumulated during saline water wash needs to be completely removed or else it will
corrode the engine parts when used as fuel. Thus, for this reason the ester layer was
given a final wash with distilled water in a similar amount as saline water.
Distilled water on the other hand is best for transesterified products that have low or
no soap formation. These can be produced from lipid source with low FFA% or
pretreated oils, which have high FFA%. Using distilled water saves washing time and
resources required to about half, as extra washing is not needed.
Chapter 4 Synthesis and Purification
86
Table 4.7 Purification of Coconut Oil Ethyl Esters with Distilled and Saline
Wash Water
Sample A - mass of crude ester before washing
Mass of empty bottle
Mass of bottle with washed ester
B - mass of washed ester
% loss of water solubles due to washing (A-B)/A x 100
C001coco-2A-WBDE 25 25.5454 40.1992 14.6538 41.38 C001coco-2A-WBDE-salt 25 25.5491 40.4395 14.8904 40.44 C001coco-2B-WBDE 25 25.628 39.7261 14.0981 43.61 C001coco-2B-WBDE-salt 25 25.8449 40.0898 14.2449 43.02 C001coco-3-WBDE 25 16.1625 24.8592 8.6967 65.21 C001coco-3-WBDE-salt 25 15.9422 24.8822 8.94 64.24
C021coco-2A-WBDE 25 25.6014 39.2408 13.6394 45.44 C021coco-2A-WBDE-salt 25 25.6908 39.2962 13.6054 45.58 C021coco-2B-WBDE 25 25.5599 39.0032 13.4433 46.23 C021coco-2B-WBDE-salt 25 25.6606 39.9213 14.2607 42.96 C021coco-3-WBDE 25 16.2675 24.6076 8.3401 66.64 C021coco-3-WBDE-salt 25 16.1945 24.995 8.8005 64.80
C031coco-2A-WBDE 25 25.8077 37.6745 11.8668 52.53 C031coco-2A-WBDE-salt 25 15.953 30.2057 14.2527 42.99 C031coco-2B-WBDE 25 15.9737 24.4222 8.4485 66.21 C031coco-2B-WBDE-salt 25 25.4518 36.1783 10.7265 57.09 C031coco-3-WBDE 25 16.2017 25.9154 9.7137 61.15 C031coco-3-WBDE-salt 25 16.2799 26.4193 10.1394 59.44
C002coco-2A-WBDE 25 15.9467 27.1843 11.2376 55.05 C002coco-2A-WBDE-salt 25 25.5156 39.1568 13.6412 45.44 C002coco-2B-WBDE 25 25.7683 40.2516 14.4833 42.07 C002coco-2B-WBDE-salt 25 25.6595 42.1851 16.5256 33.90 C002coco-3-WBDE 25 16.2226 26.1304 9.9078 60.37 C002coco-3-WBDE-salt 25 16.2431 26.6536 10.4105 58.36
C022coco-2A-WBDE 25 25.5768 37.1604 11.5836 53.67 C022coco-2A-WBDE-salt 25 25.6593 40.4089 14.7496 41.00 C022coco-2B-WBDE 25 25.5353 39.7721 14.2368 43.05 C022coco-2B-WBDE-salt 25 25.5353 39.7721 14.2368 43.05 C022coco-3-WBDE 25 15.8318 22.1236 6.2918 74.83 C022coco-3-WBDE-salt 25 16.2012 25.6564 9.4552 62.18
C032coco-2A-WBDE 25 25.7651 42.6591 14.5321 41.87 C032coco-2A-WBDE-salt 25 25.7459 41.2189 15.473 38.11 C032coco-2B-WBDE 25 25.6933 39.3702 13.6769 45.29 C032coco-2B-WBDE-salt 25 25.7043 41.3233 15.619 37.52 C032coco-3-WBDE 25 15.8611 26.7554 10.8943 56.42 C032coco-3-WBDE-salt 25 16.2131 27.4264 11.2133 55.15
Note: samples washed with saline water are denoted with prefix – salt.
Chapter 4 Synthesis and Purification
87
As can be seen for table 4.7 the percentage of water solubles lost during the process of
washing is slightly less or equivalent to samples washed in both samples that are
washed with distilled water and saline water. It should be noted that major loss of
ester does not occur due to extra washing required to remove salinity when washed
with saline water.
4.3.4 Infrared analysis
After washing the Infrared analysis of each sample was carried out. The spectra
Figure 4.15 Infrared Spectra of Ester Before Purification Process
Figure 4.16 Infrared Spectra of Ester After Purification Process
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
0.0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
84.9
cm-1
%T
3457,78
3005,32
2926,0
2853,4
1740,1
1652,76
1644,78
1463,28
1373,36
1345,54
1302,48
1243,33
1181,16
1113,49
1097,45
1034,41
970,78
916,74 859,74
724,49
2734,792677,79
Chapter 4 Synthesis and Purification
88
The characteristic absorption peak of alcohol is usually a strong broad band between
3400-3650 cm-1. Peak at 3525 cm-1 and 3457 cm-1 in figure 4.16 explains the presence
of methanol/ethanol/water in the sample. This peak confirms that there is extremely
low amount of alcohol or water present.
Chapter 5 Chemical and Physical Analysis of Biodiesel
89
5 CHAPTER 5 CHEMICAL AND PHYSICAL ANALYSIS
OF BIODIESEL
5.1 INTRODUCTION
The use of biodiesel as an alternative to automotive diesel fuel and its efficiency as
fuel depends solely on its quality. Biodiesel standards have been established to
maintain the consistency in the fuel quality by characterizing biodiesel fuel, see
chapter 2. The fatty acid composition of the lipid raw material is the major factor
influencing the fuel properties of biodiesel fuel. These include its physical and
chemical properties. As a consequence the quality control of the oleo chemical
products is essential in biodiesel production. Some common fatty acids and their ester
are listed in table 5.1 below. Accordingly the analytical methods employed to
determine these are of great significance.
Table 5.1 Some Common Fatty Acids and There Esters
Fatty Acid Structure of Its Esters* Common Acronym
(Methyl)/(Ethyl) Ester
Lauric acid/ Dodecanoic acid
R-(CH2)10-CH3 C12:0 M/E Laurate or M/E Dodecanoate
Palmitic acid/ Hexadecanoic acid
R-(CH2)14-CH3 C16:0 M/E Palmitate M/E Hexadecanoate
Stearic acid/ Octadecanoic acid
R-(CH2)16-CH3 C18:0 M/E Stearate M/E Octadecanoate
Oleic acid/ 9(Z)- Octadecanoic acid
R-(CH2)7-CH= CH-(CH2)7-CH3
C18:1 M/E Oleate M/E 9(Z)- octadecanoate
Linoleic acid/ 9(Z),12(Z)-
octadecadienoic acid
R-(CH2)7-CH= CH-CH2-CH=CH-(CH2)4-CH3
C18:2 M/E Linoleate M/E 9(Z),12(Z)-
octadecadienoate Linolenic acid/
9(Z),12(Z),15(Z)- octadecatrienoic
R-(CH2)7-(CH= CH-CH2)3-CH3
C18:3 M/E Linolenate M/E 9(Z),12(Z),
15(Z) octadecatrienoate * Methyl ester R = -CO2-CH3 and Ethyl Esters R = -CO2-C2H5
Chapter 5 Chemical and Physical Analysis of Biodiesel
90
Factors Affecting Fuel Quality
The chemical contaminants escaping through the purification processes are a major
cause of degradation in the quality of biodiesel fuel. Contaminant can be by-products,
reactants or incomplete transesterified products. Unreacted triglyceride and other
acylglycerols intermediates (monoglyceride and diglycerides) are formed during the
course of transesterification reaction. For example, intermediates formed when
trilauric acid undergoes transesterification shown in figure 5.1. The triglycerides,
diglycerides and monoglycerides are partially composed of bound glycerol. This is
added to free glycerol to get total glycerol. Together with these contaminants, residual
alcohol and wash water content have an existing limit for its permissible levels in
biodiesel fuel.
Figure 5.1 Intermediates formed from transesterification of trilauric acid
Physical parameters also contribute to the quality of biodiesel fuel. The physical
factors are also majorly due to the type and source of the lipid raw material and the
synthetic process. Some of these fuel properties are also applicable to conventional
diesel fuel. The lipid raw material of biodiesel fuel is basically reflected by the nature
and composition of fatty acids present in it. This has an effect on the oxidation and
stability of the final biodiesel product. Some physical factors include viscosity, cold
temperature properties, cetane number, heating value, flash point and density.
CH2OH
CH2OH
CH2OOR1
Monoglyceride
CH2OH
CH2OOR1
CH2OOR1 Diglyceride
Where R1 = (CH2)10-CH3
Chapter 5 Chemical and Physical Analysis of Biodiesel
91
Table 5.2 Property Data for Methyl Ester Biodiesel Fuels 91
Source oil Density
Viscosity
cSt@40 C
Cetane
Heating Value
MJ/kg
Cloud point C
Palm 0.880 5.7 62 37.8 +13
Soybean 0.884 4.08 46.2 39.8 +2
Sunflower 0.880 4.6 49 38.1 +1
Tallow 0.887 4.1 58 39.9 +12
Biodiesel Analytical Methods
Several chromatographic, spectrometric and wet chemistry (mostly to determine
physical properties) analytical methods have been carried out to determine the quality
of fuel. Gas chromatography (GC) technique has been identified as the most common
instrumentation method for biodiesel characterization. High Pressure Liquid
Chromatography (HPLC) 92 technique is the next popular. Other methods include
Thin Layer Chromatography (TLC), Nuclear Magnetic Resonance (NMR)
spectroscopy93, Ultraviolet (UV) spectroscopy94 and Near Infrared (NIR)
spectroscopy95.
The ester contents and in biodiesel using gas chromatographic techniques have been
carried out using Flame Ionization Detectors (FID). Its quantification has been done
using the method of internal standards, external standards or calibration method.
Methyl heptadecanoate is considered to be a common internal standard mainly as
heptadecanoic acid is an uncommon naturally occurring fatty acid in some vegetable
oils. However, its natural presence has been found in animal fat and oil which resulted
in showing increased ester content (2-7%w/w) as compared to results obtained using
EN 14103 uniform European quality standard method for fatty acid methyl ester
(FAME). Other detectors used includes Mass Spectorscopy (MS) detector that is
Chapter 5 Chemical and Physical Analysis of Biodiesel
92
coupled with GC for fragment identification. Use of appropriate temperature-
programming methods in GC technique enable separating and quantification of short
chain fatty acid esters (C8-C12) in coconut, palm and kernel oil. Some parameters of
analyzing biodiesel in Gas Chromatography are given in table 5.3.
For analysis of contaminants in biodiesel described earlier, derivatisation during
sample preparation is essential as this improves the irregularity in to procedure by
showing excellent peak shapes, good recoveries and low detection limits. Some
derivatising agents used include N, O-bis trimethylsilyltrifluoroacetamide (BSTFA),
N-Methyl –N-trimethylsilyltrifluoroacetamide (MSTFA). 1,4-butanediol and 1,2,4-
butanetriol have been used as internal standards for free glycerol detection.
Table 5.3. Summary of Some Parameters for Analysing Biodiesel in Gas
Chromatography.
Column Details
l x id x ft (phase)
Detector*
Temperature
(˚C)
Injector
Temperature
(˚C)
Oven Program
30m x 0.25mm x 0.25µm
(Polyethylene glycol)
250 250 165-180˚C (4 ˚C/min)
180-200˚C (5 ˚C/min)
200-260˚C (15
˚C/min)
260˚C (2 min)
25m x 0.53mm x 1µm
(acidified polyethylene glycol)
- - 180-200˚C (4 ˚C/min)
25m x 0.32mm x 0.52 µm (5%
diphenyl and 95% dimethyl
polysiloxane)
280 250 150-225˚C (5 ˚C/min)
30m x 0.32mm x 1µm 300 300 190-215˚C (6 ˚C/min)
215-300˚C (4 ˚C/min)
* Flame Ionization Detector
Atmospheric Pressure Chemical Ionisation Mass Spectrometry (APCI-MS) detection
technique when coupled with reverse phase HPLC was found to be most suitable for
Chapter 5 Chemical and Physical Analysis of Biodiesel
93
analysis of biodiesel. This was reported by Holcapek et. al (1999) after an extensive
study on different detectors used with HPLC analytical technique. UV detection at
205nm and Evaporative Light Scattering Detectors (ELSD) were also explored.
Gel Permeation Chromatography (GPC) or gel filtration chromatography, also known
as Size Exclusion Chromatography (SEC) employees a separation mechanism
technique. Separation of analyte occurs according to its hydrodynamic volume or
hydrodynamic diameter. It encompasses similar instrumentation set up to HPLC
(technique by physical state of mobile phase) except the nature of the column. More
than one column can be used for better separation96. Table 5.4 contains a summary of
some analytical condition used during HPLC analysis.
Table 5.4. Summary of Some Parameters for Analysing Biodiesel by High
Performance Liquid Chromatography97.
Column Details
l x id ( TM)
Flow
Rate
(ml/min)
Injection
Loop (µl)
Temperature
(˚C)
Mobile Phase
250mm x 4.6mm (STRODS-II) 1 - 40 Methanol
250mm x 4mm (LiChro CART
RP-C18)
1 10 - Hexane:isopropano
l:methanol
300mm x 7.8mm (GPC-
Styragel)
1 500 - Toluene
300mm x 7.5mm (GPC-
Styragel)
- 35-40 tetrahydrofuran
So far in this research the suitable raw materials have been identified (chapter 3) and
these have been used to synthesize biodiesel through the various tranesterification
methods described in chapter 4. After the purification process these samples are now
ready for chemical and physical analysis.
Chapter 5 Chemical and Physical Analysis of Biodiesel
94
This chapter greatly investigates Gas Chromatography and Gel Permeation
Chromatography as suitable chemical analysis for biodiesel analysis in Fiji. These
methods are greatly explored in the next section. It discusses the analysis of methyl
and ethyl ester (biodiesel) followed by analysis of mono-, di- and triglycerides
(contaminants). Gas Chromatography – Mass Spectrocopy analysis was carried
overseas for confirmation of the biodiesel composition. The viscosity of these
biodiesel samples is also determined as a physical parameter. The pros and cons of
GC and GPC are later discussed.
Chapter 5 Chemical and Physical Analysis of Biodiesel
95
5.2 METHYL AND ETHYL ESTERS (BIODIESEL)
5.2.1 Gas Chromatography – Flame Ionisation Detector (FID)
5.2.1.1 Methodology
Sample preparation
250 mg of biodiesel sample was accurately weighed on an analytical balance in two
10ml screw cap glass vial. 5 ml of freshly prepared 10mg/ml methyl heptadecanoate
solution (internal standard) which was prepared in a 50ml volumetric flask by
dissolving 500mg of methyl heptadecanoate in heptane and diluting up to the mark
was then added to one vial So. To the other vial added 5ml of heptane was added and
this was labeled Rf. The vials were closed and shaken homogeneously after which 1µl
of this solution was analyzed for its ester content in gas chromatography. After each
injection the syringe was washed with heptane and then washed with the sample
several times. Washing was carried out repeatedly to ensure that the syringe is clean
and there is no contamination. This procedure was carried out for methyl and ethyl
esters of waste oil and methyl and ethyl ester of coconut oil analysis.
Feedstock such as animal fat and lauric oils may contain naturally occurring
heptadecanoate acids (C17:0). In a recent study, Schober et al98 discovered that, when
esterified, the peaks areas of heptadecanoate esters in biodiesel samples interfere with
the internal standard resulting in lowering of the real ester content in the sample. Also,
the shorter chain fatty acid esters from caprylic (C8:0) and lauric (C12:0) acid are
excluded from the calculation according to the European standards EN 14103 method.
Thus the method described is a modification of EN 14103 method that has been
Chapter 5 Chemical and Physical Analysis of Biodiesel
96
recommended for biodiesel derived from animal fat and lauric oil such as coconut oil
and some waste oil.
Chromatographic analysis
Determination of ester content of the samples were analysed by gas chromatography
technique on a Clarus 500 GC apparatus equipped with Total Chrom version 6.2.0
software. A non-bonded cyanosilicone phase capillary column was used.
Table 5.5 Gas Chromatography FID Instrumentation Condition for Biodiesel
Analysis
Column: SP2330 (supelco)
60m x 0.32mm ID x 0.20µm film.
Cat. No: 2-4074
Oven: Initial temperature: 200°C,
Initial hold: 0.00 min
Equiliberation time: 2.00min
Ramp 1: 2.0 °C/min to 210°C, hold for 10.00 min
Ramp 2: 4.0 °C/min to 250°C, hold for 0.00 min
Total run time: 25.00 min
Carrier: Nitrogen at 10.8 psi Head pressure
Injector: Split mode
Temperature: 290°C
Injection volume 1 µl
Detector:
Flame Ionization Detector
Temperature: 250°C
Spilt flow ratio: 100:1
Split flow rate: 71 ml/min
Chapter 5 Chemical and Physical Analysis of Biodiesel
97
Expression of results
The ester content C is expressed as percentage (wt %) and is calculated using this
equation:
Where;
ΣA is the total peak area from the methyl ester C14 to that in C24:1,
AEI is the peak corresponding to methyl heptadecanoate in sample So,
AER is the peak corresponding to methyl heptadecanoate of the Rf sample,
CEI is the concentration (mg/ml) of methyl heptadecanoate solution being used,
VEI is the volume (ml) of the methyl heptadecanote solution being used,
W is the weight (mg) of sample.
C =( ) ( )
( ) 100××
×−
−−∑W
VC
AA
AAAEIEI
EREI
EREI
Chapter 5 Chemical and Physical Analysis of Biodiesel
98
5.2.1.2 Results
Methyl esters of Coconut oil
Table 5.6 Calculation of the Percentage Methyl Ester in the Samples (GC-FID)
Samples
W mass of sample (mg)
∑∑∑∑A E
(∑A-Aei)/Aei
F (Cei x Vei)/W
E x F x 100* (%)
1 C001coco-2A-WBDM 252.30 140051.61 4.9093 0.1982 97.2919 2 C001coco-2B-WBDM 253.30 144437.91 4.6349 0.1974 91.4912 3 C001coco-1-WBDM 253.00 136726.27 4.6189 0.1976 91.2817
4 C021coco-2A-WBDM 252.30 125583.44 4.8768 0.1982 96.6467 5 C021coco-2B-WBDM 250.60 137748.08 5.3466 0.1995 106.6758 6 C021coco-1-WBDM 252.40 135660.29 6.1843 0.1981 122.5102
7 C031coco-2A-WBDM 250.20 122219.33 4.9788 0.1998 99.4960 8 C031coco-2B-WBDM 250.30 163201.93 5.6480 0.1998 112.8239 9 C031coco-1-WBDM 253.10 131789.07 4.6481 0.1976 91.8243
10 C002coco-2A-WBDM 254.20 123112.32 5.4693 0.1967 107.5793 11 C002coco-2B-WBDM 250.30 129949.29 4.0949 0.1998 81.7998 12 C002coco-1-WBDM 254.00 145470.09 5.0082 0.1969 98.5871
13 C022coco-2A-WBDM 253.70 112880.61 4.6391 0.1971 91.4298 14 C022coco-2B-WBDM 254.40 148341.01 4.8351 0.1965 95.0289 15 C022coco-1-WBDM 251.70 149325.53 4.8535 0.1986 96.4135
16 C032coco-2A-WBDM 251.80 134128.02 5.8776 0.1986 116.7125 17 C032coco-2B-WBDM 254.20 134329.30 4.7768 0.1967 93.9570 18 C032coco-1-WBDM 253.80 110627.59 4.8742 0.1970 96.0235
* The percentage is calculated based on the peaks identified in table A.28.
Chapter 5 Chemical and Physical Analysis of Biodiesel
99
Ethyl esters of Coconut oil
Table 5.7 Calculation of the Percentage Ethyl Ester in the Samples (GC- FID)
Samples W mass of sample
(mg)
åA E (åA-
Aei)/Aei
F (Cei x Vei)/W
E x F x 100* (%)
1 C001coco-2A-WBDE 253.5 33452.31 0.2703 0.1972 5.3310
2 C001coco-2A-WBDE-salt 252.3 35404.15 0.3557 0.1982 7.0492
3 C001coco-2B-WBDE 253.6 29217.72 0.0292 0.1972 0.5762
4 C001coco-2B-WBDE-salt 254.7 27367.37 0.0315 0.1963 0.6184
5 C001coco-3-WBDE 251.5 131553.15 3.8810 0.1988 77.1579
6 C001coco-3-WBDE-salt 250.6 128503.41 4.5513 0.1995 90.8073
7 C021coco-2A-WBDE 252.1 28378.31 0.0678 0.1983 1.3444
8 C021coco-2A-WBDE-salt 251.3 29709.83 0.0809 0.1990 1.6103
9 C021coco-2B-WBDE 254.9 24894.99 0.0444 0.1962 0.8706
10 C021coco-2B-WBDE-salt 252 28859.51 0.0429 0.1984 0.8519
11 C021coco-3-WBDE 251.4 119417.17 3.3303 0.1989 66.2348
12 C021coco-3-WBDE-salt 254 97876.76 2.8172 0.1969 55.4564
13 C031coco-2A-WBDE 253.4 28766.12 0.0804 0.1973 1.5856
14 C031coco-2A-WBDE-salt 250.6 28006.84 0.0974 0.1995 1.9437
14 C031coco-2B-WBDE 255.6 24074.63 0.0307 0.1956 0.6011
15 C031coco-2B-WBDE-salt 251.3 27534.14 0.0253 0.1990 0.5036
16 C031coco-3-WBDE 254 128703.70 4.6807 0.1969 92.1398
17 C031coco-3-WBDE-salt 254.7 102474.90 2.8173 0.1963 55.3067
18 C002coco-2A-WBDE 252.8 24301.17 0.1385 0.1978 2.7384
19 C002coco-2A-WBDE-salt 252.6 25664.37 0.1478 0.1979 2.9261
20 C002coco-2B-WBDE 254.6 28104.67 0.0280 0.1964 0.5497
21 C002coco-2B-WBDE-salt 253.5 28611.76 0.0391 0.1972 0.7719
22 C002coco-3-WBDE 254.2 84947.90 3.1197 0.1967 61.3630
23 C002coco-3-WBDE-salt 252.7 86142.09 2.3411 0.1979 46.3227
24 C022coco-2A-WBDE 251.8 30447.54 0.2728 0.1986 5.4176
25 C022coco-2A-WBDE-salt 254.3 32147.52 0.2858 0.1966 5.6189
26 C022coco-2B-WBDE 251.3 28823.51 0.0550 0.1990 1.0943
27 C022coco-2B-WBDE-salt 250.5 25173.87 0.0741 0.1996 1.4793
28 C022coco-3-WBDE 250.5 102020.43 2.4436 0.1996 48.7754
29 C022coco-3-WBDE-salt 251.2 73587.66 3.1845 0.1990 63.3852
30 C032coco-2A-WBDE 251.2 42506.32 0.6173 0.1990 12.2873
31 C032coco-2A-WBDE-salt 254.3 28096.31 0.5914 0.1966 11.6276
32 C032coco-2B-WBDE 251 28576.43 0.3510 0.1992 6.9926
33 C032coco-2B-WBDE-salt 252 29241.07 0.3301 0.1984 6.5489
34 C032coco-3-WBDE 253.5 74071.81 2.6956 0.1972 53.1683
35 C032coco-3-WBDE-salt 251.1 71051.09 3.1011 0.1991 61.7512 * The percentage is calculated based on the peaks identified in table A.29.
Chapter 5 Chemical and Physical Analysis of Biodiesel
100
Methyl esters of Waste Oil
Table 5.8 Calculation of the Percentage Methyl Ester in the Samples (GC-FID)
Samples
W mass of sample
(mg)
∑∑∑∑A E
(∑A-Aei)/Aei
F (Cei x Vei)/W
E x F x 100* (%)
1 W001p-1-WBDM 250.40 4289.25 1.4507 0.1997 28.9672 2 W021p-1-WBDM 250.20 5784.92 1.4115 0.1998 28.2072 3 W031p-1-WBDM 252.60 5417.45 1.4550 0.1979 28.8007
4 W002s-1-WBDM 254.90 4492.35 1.5033 0.1962 29.4881 5 W022s-1-WBDM 251.40 6015.81 1.2644 0.1989 25.1475 6 W032s-1-WBDM 251.90 10317.08 2.9247 0.1985 58.0521
7 W003s-2A-WBDM 254.20 3788.11 1.4421 0.1967 28.3657 8 W023s-1-WBDM 252.90 4643.76 1.3625 0.1977 26.9374 9 W033s-2A-WBDM 251.90 4599.13 1.2861 0.1985 25.5289
* The percentage is calculated based on the peaks identified in table A.30.
Ethyl esters of waste oil
Table 5.9 Calculation of the Percentage Ethyl Ester in the Samples (GC-FID)
Samples
W mass of sample
(mg)
∑∑∑∑A E
(∑A-Aei)/Aei
F (Cei x Vei)/W
E x F x 100* (%)
1 W001p-3-WBDE 252.50 4428.10 1.5205 0.1980 30.1096
2 W021p-3-WBDE 253.70 2698.43 1.4579 0.1971 28.7328
3 W031p-3-WBDE 251.30 2954.77 1.5481 0.1990 30.8017
4 W002s-3-WBDE 250.90 2509.48 1.4281 0.1993 28.4594
5 W022s-3-WBDE 252.50 2714.15 1.3256 0.1980 26.2497
6 W032s-3-WBDE 252.60 2664.04 1.3066 0.1979 25.8624
7 W003s-3-WBDE 254.00 3656.53 1.5167 0.1969 29.8558
8 W023s-3-WBDE 254.50 3848.14 1.4248 0.1965 27.9925
9 W033s-3-WBDE 253.70 3055.85 1.3181 0.1971 25.9774 * The percentage is calculated based on the peaks identified in table A.31.
Chapter 5 Chemical and Physical Analysis of Biodiesel
101
5.2.1.3 Discussion
The following ester components were identified from the coconut oil esters prepared
using different experimental methods:
Caprylic acid methyl ester (C8:0), Capric acid methyl ester (C10:0), Lauric acid
methyl ester (C12:0), Myristic acid methyl ester (C14:0), Palmitic acid methyl ester
(C16:0), Stearic acid methyl ester (C18:0), Oleic acid methyl ester (C18:1), Linoleic
acid methyl ester (C18:2). These esters were used in calculating the percentage yield.
Similarly, the ethyl forms of these esters were also identified in ethyl esters of
coconut oil samples produced.
The analytical methodology given in the gas chromatography instrumentation
standard methods are modified as it is not suitable for kennel or palm oil ester.
Temperature programming has been employed to distinctly separate and prevent
overlap of low carbon ester peaks present in coconut oil. Columns with different
polarity were also investigated. Several trials of different temperature programming
methods have been done and the most efficient methodology was used for analysis.
Adaptation of other GC instrumentation methods for biodiesel99 and its
contaminant100 analysis proved to be useful.
Also note that naturally occurring methyl heptadecanoate does not interfere with other
ester peaks present in coconut oil biodiesel samples as seen figure 5.2 chromatogram
A and B
Chapter 5 Chemical and Physical Analysis of Biodiesel
102
4
6
8
10
12
14
16
18
20
8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5
10.74
10.36
9.82
11.21 11.61 12.24
9.45
9.22
9.06
Chromatogram A: C002coco-2A-WBDM-So
4
6
8
10
12
14
16
18
20
22
24
8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5
8.919.07
9.29
9.65
10.20
11.0311.45
12.06
Chromatogram B: C002coco-2A-WBDM-Rf Figure 5.2 Purified Coconut Oil Methyl Ester Synthesized Using Method 2A.
Chromatogram B shows absence of naturally occurring methyl heptadecanoate (MH) in
sample c.f chromatogram A (spiked with MH).
As there was not any methyl heptadecanoate naturally occurring in the sample, the
correction by subtraction as documented in the method was not carried out.
Methyl heptdecanoate
Chapter 5 Chemical and Physical Analysis of Biodiesel
103
Table 5.10 Percentage Concentration of Methyl Esters Analysed by GC FID
Methyl ester Method Range (%) Median (%) Waste oil (Methyl
oleate)
1 28.49-25.15 28.21
Coconut oil (Methyl
laurate)
1 122.51-91.28 96.22
2A 116.71-91.43 98.39
2B 112.82-81.80 94.49
The retention times of the esters used for identification of the respective peaks are
given in the Appendix
Figure 5.3 Percentage of Methyl Laurate in Coconut Oil Methyl Ester (GC-FID)
When comparing the coconut oil esters from different methods of production,
synthetic method 2A indicated to be a better method in terms of the median
percentage of ester . However, method 2A has a wider percentage range (116.71%-
91.43%) that overlaps with the percentage range obtained using synthesis method 1
96.22
98.39
94.49
92
93
94
95
96
97
98
99
Est
er C
onte
nt (
%)
1 2A 2B
Biodiesel Synthetic Methods
Ester Content of Biodiesel in Coconut Oil Methyl Es ters
Chapter 5 Chemical and Physical Analysis of Biodiesel
104
(122.51%-91.28%). Thus, method 1 is as effective as 2A. Synthetic method 2B has a
slightly lower yield comparatively.
Methyl esters from waste oil showed percentage yield from 28.49%-25.15%. More
ester constituents were considered while calculating these values that makes it
incomparable with coconut oil methyl esters prepared using different methods.
However, it still indicates a very low yield even after considering the unidentified
peaks.
Figure 5.4 Purified waste oil methyl ester synthesized using method 3 (GC-FID).
Table 5.11 Percentage Concentration of Ethyl Esters Analysed by GC-FID
Ethyl ester Method Range (%) Median (%)
Ethyl oleate 3 30.80-25.86 28.46
Ethyl laurate 3 92.14-46.32 61.56
2A 12.29-1.34 4.13
2B 6.99-0.50 0.81
5.00
5.10
5.20
5.30
5.40
5.50
5.60
7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5
7.72 8.16
8.83
9.79
10.16
10.74
Chapter 5 Chemical and Physical Analysis of Biodiesel
105
4.130.82
61.56
0
10
20
30
40
50
60
70
Est
er C
onte
nt (
%)
2A 2B 3
Biodiesel Synthetic Methods
Ester Content of Biodiesle in Coconut Oil Ethyl Est ers
Figure 5.5 Percentage of Methyl Laurate in Coconut Oil Ethyl Ester (GC-FID)
For ethyl ester, similar comparison is done to determine the best method of biodiesel
synthesis. Method 3 is the best of the other 2 methods employed (method 2A and
method 2B). The percentage yields of ester obtained are lower than methyl esters for
the same oil. However, unlike coconut oil ethyl esters, waste oil ethyl esters show
percentage yield to be consistence with its methyl esters.
There was no difference in the composition of esters observed with coconut oil ethyl
esters when washed with saline water as expected. Saline water can be used
efficiently in the purification process as described in chapter 4. This can be done
without compromising the quality of biodiesel.
Chapter 5 Chemical and Physical Analysis of Biodiesel
106
Figure 5.6 Purified Coconut Oil Ethyl Ester (GC-FID) showing similar profile.
Purification by salt water and distilled water show similar profile
6
8
10
12
14
16
7.8 8.0 8.2 8.4 8.6 8.8 9.0 9.2 9.4 9.6 9.8 10.0 10.2 10.4 10.6 10.8 11.0 11.2 11.4 11.6 11.8
8.188.34
8.57
8.96
9.57
10.5710.96 11.63
Chromatogram: C001coco-3-WBDE-salt So
Chapter 5 Chemical and Physical Analysis of Biodiesel
107
5.2.2 Gel Permeation Chromatography
5.2.2.1 Methodology101
Sample preparation
300mg of biodiesel sample was weighed out on an analytical balance in a 10ml screw
cap vial and diluted with 5ml HPLC grade tetrahydrofuran. The solution was mixed
well after closing the vial and filtered using a glass syringe having a 0.2µm nylon
syringe filter.10µl of the filtered solution was then analyzed in gel permeation
chromatography (GPC) instrument. Tetrahydrofuran was filtered with 0.45µm nylon
filter paper before use. All glassware used for this analysis was made of glass.
Standard preparation
The respective methyl and ethyl ester standards were quantified in coconut oil and
waste oil. Methyl ester standards included methyl oleate (waste oil) and methyl
laurate (coconut oil) while Ethyl ester standards were Ethyl Oleate (waste oil) and
Ethyl Laurate (coconut oil). These standards were prepared in different
concentrations (table 5.12 – table 5.15) and 10µl of each were analyzed in a GPC
system described below.
A calibration curve was plotted using the peak area of these standards versus its
concentration to determine the concentration of methyl the respective methyl and
ethyl ester in coconut and waste oil biodiesel prepared using the various synthetic
methods in this research.
Chapter 5 Chemical and Physical Analysis of Biodiesel
108
Table 5.12 Peak Area versus Concentration of Methyl Oleate
Concentration (mg/ml) Area (V*sec)
26.0 1400000
25.5 1360002
22.0 1161610
19.5 1003473
16.0 862090
13.5 720942
Figure 5.7 Calibration Curve of Methyl Oleate
Table 5.13 Peak Area versus Concentration of Methyl Laurate
Concentration (mg/ml) Area (V*sec)
10 217013
12 247119
14 279945
16 323461
18 370137
20 403793
y = 53679x - 11267
R2 = 0.9957
0
200000
400000
600000
800000
1000000
1200000
1400000
1600000
0 5 10 15 20 25 30
Concentration (mg/ml)
Are
a (M
V)
Chapter 5 Chemical and Physical Analysis of Biodiesel
109
Figure 5.8 Calibration Curve of Methyl Laurate
Table 5.14 Peak Area versus Concentration of Ethyl Oleate
Concentration (mg/ml) Area (V*sec)
20 1068207
18 961203
16 853980
14 743750
12 639060
10 540325
Figure 5.9 Calibration Curve of Ethyl Oleate
y = 19235x + 18382
R2 = 0.9946
050000
100000150000200000250000300000350000400000450000
0 5 10 15 20 25
Concentration (mg/ml)
Are
a (M
V)
y = 53087x + 4787
R2 = 0.9997
0
200000
400000
600000
800000
1000000
1200000
0 5 10 15 20 25
Concentration (mg/ml)
Are
a (M
V)
Chapter 5 Chemical and Physical Analysis of Biodiesel
110
Table 5.15 Peak Area versus Concentration of Ethyl Laurate
Concentration (mg/ml) Area (V*sec)
0.5 7988
3.5 60063
6.5 99945
9.5 160007
12.5 210232
15.5 260371
17.5 300012
Figure 5.10 Calibration Curve of Ethyl Laurate
Chromatographic analysis
The biodiesel samples were analyzed for its ester content and contaminants such as
glycerides using size exclusion chromatography. The GPC system consists of Water
1515 isocratic HPLC pump, Waters 717 plus Autosampler, Waters 2414 Refractive
Index (RI) Detector and Breeze software.
y = 17108x - 3133.5
R2 = 0.9985
0
50000
100000
150000
200000
250000
300000
350000
0 5 10 15 20
Concentration (mg/ml)
Are
a (M
V)
Chapter 5 Chemical and Physical Analysis of Biodiesel
111
Table 5.16 Gel Permeation Chromatography instrumentation conditions for
Biodiesel analysis
Column Two phenogel 50 Å (phenomenex) connected in series
300mm x 7.8mm x 5 microns
Mobile phase Tetrahydrofuran (HPLC grade)
Flow rate 1 ml/min at room temperature.
RI detector Temperature 28.7 °C
Sensitivity 4
Injection volume 10 µl
Run time 22 min
Chapter 5 Chemical and Physical Analysis of Biodiesel
112
5.2.2.2 Results
Methyl esters of Waste oil
Table 5.17 Concentration of Methyl Oleate in Waste Oil Biodiesel Samples (GPC)
Sample Retention
time (min)
Methyl
Oleate
peak area
(V*sec)
A Concentration
of Methyl oleate
(mg/ml)
B mass of
sample
[(A x
5ml*)/B] x
100 (%)
W001p-1-WBDM 13.433 1263283 23.324 303.5 38.4253
W021p-1-WBDM 13.44 1247793 23.036 304.1 37.8750
W031p-1-WBDM 13.388 1215638 22.437 303.3 22.5532
W002s-1-WBDM 13.434 1314988 24.287 304.7 39.8545
W022s-1-WBDM 13.386 1177009 21.717 300.4 36.1467
W032s-1-WBDM 13.389 1040084 19.166 300.9 31.8480
W003s-1-WBDM 13.387 1258811 23.241 301.7 38.5164
W023s-1-WBDM 13.426 1283123 23.694 304.9 38.8549
W033s-1-WBDM 13.419 1240500 22.899 301.4 37.9889
* 5ml is the volume of THF
Note: all samples were prepared using Acid pretreatment methodology.
Chapter 5 Chemical and Physical Analysis of Biodiesel
113
Methyl esters of Coconut oil
Table 5.18 Concentratrion of Methyl Laurate in Coconut Oil Biodiesel Samples
(GPC)
Sample Methyl
Laurate
peak
area
B
Mass of
samples
(g)
A
Concentration of Methyl
Laurate (mg/ml)
[(A x 5ml*)/B] x 100
(%)
2A 2B 1 2A 2B 1
C001coco-2A-WBDM 349482 301.6 17.213 28.537
C001coco-2B-WBDM 329675 305.1 16.184 26.522
C001coco-1-WBDM 343967 301 16.927 28.117
C021coco-2A-WBDM 331957 300.5 16.302 27.125
C021coco-2B-WBDM 331914 302.7 16.300 26.925
C021coco-1-WBDM 347752 301.5 17.123 28.397
C031coco-2A-WBDM 343272 304.8 16.891 27.529
C031coco-2B-WBDM 324389 302.8 15.909 26.270
C031coco-1-WBDM 350460 303.1 17.264 28.479
C002coco-2A-WBDM 313523 302.5 15.344 25.362
C002coco-2B-WBDM 289013 304.3 14.070 23.118
C002coco-1-WBDM 338022 302.1 16.618 27.504
C022coco-2A-WBDM 336835 300.7 16.556 27.529
C022coco-2B-WBDM 332735 301.3 16.343 27.120
C022coco-1-WBDM 340914 304.9 16.768 27.498
C032coco-2A-WBDM 346318 301.8 17.049 28.245
C032coco-2B-WBDM 342281 302.8 16.839 27.806
C032coco-1-WBDM 342763 301.3 16.864 27.986
2A (One Step Base Transesterification), 2B (Two Step Base Transesterification) and 1 (Acid
pretreatment, one-step basic transesterification) are synthetic methods for biodiesel production used
in this research (refer to chapter 4).
Chapter 5 Chemical and Physical Analysis of Biodiesel
114
Ethyl esters of Waste oil
Table 5.19 Concentration of Ethyl Oleate in Waste Oil Biodiesel Samples (GPC)
Sample Retenti
on time
(min)
Ethyl
Oleate
peak area
A Concentration
of Methyl oleate
(mg/ml)
B mass
of
sample
[(A x 5ml*)/B]
x 100 (%)
W001p-3-WBDE 13.05 987922 18.519 302.6 30.6003
W021p-3-WBDE 13.012 579300 10.822 301.4 17.9531
W031p-3-WBDE 13.019 756459 14.159 304.9 23.2195
W002s-3-WBDE 13.022 637504 11.918 301.6 19.7588
W022s-3-WBDE 12.996 788110 14.755 302.8 24.3650
W032s-3-WBDE 12.984 703472 13.161 302.0 21.7900
W003s-3-WBDE 13.007 934246 17.508 303.9 28.8059
W023s-3-WBDE 13.034 1028822 19.290 305.0 31.6225
W033s-3-WBDE 13.064 912674 17.102 303.4 28.1837
* 5ml is the volume of THF.
All samples were prepared using synthetic method 3 (Base Neutralisation One Step Base
Transesterification).
Chapter 5 Chemical and Physical Analysis of Biodiesel
115
Ethyl esters of Coconut oil
Table 5.20 Concentratrion of Ethyl Laurate in Coconut Oil Biodiesel Samples
(GPC)
Sample Ethyl Laurate
peak area
Concentration of Ethyl Laurate (mg/ml)
B mass of
sample
[(A x 5ml*)/B] x 100 (%)
2A 2B 3 2A 2B 3 C001coco-2A-WBDE 30942 1.625 301.8 2.693 C001coco-2A-WBDE-salt 33394 1.769 305.8 2.892 C001coco-2B-WBDE 14389 0.658 301.6 1.603 C001coco-2B-WBDE-salt 19847 0.977 302 1.618 C001coco-3-WBDE 276079 15.954 305.2 26.137 C021coco-2A-WBDE 23409 1.185 302.6 1.958 C021coco-2A-WBDE-salt 23539 1.193 304.7 1.957 C021coco-2B-WBDE 19952 0.983 302.5 1.625 C021coco-2B-WBDE-salt 20293 1.003 303.4 1.653 C021coco-3-WBDE 197916 11.096 301.4 18.888 C021coco-3-WBDE-salt 192957 11.385 302.6 18.334 C031coco-2A-WBDE 18715 0.911 305.5 1.556 C031coco-2A-WBDE-salt 15597 0.951 302.9 1.203 C031coco-2B-WBDE 17369 0.832 305.5 1.362$ C031coco-2B-WBDE-salt 19395 0.729 302.9 1.503 C031coco-3-WBDE 179787 10.326 302.9 17.045 C031coco-3-WBDE-salt 186599 10.724 301.2 17.802 C002coco-2A-WBDE 10650 1.439 302.2 0.727 C002coco-2A-WBDE-salt 22554 1.135 304.1 1.866 C002coco-2B-WBDE 18092 0.874 302.5 1.445 C002coco-2B-WBDE-salt 17828 0.859 302.3 1.421 C002coco-3-WBDE 176481 10.133 304.3 16.649 C002coco-3-WBDE-salt 180224 10.351 302.3 17.121 C022coco-2A-WBDE 22635 1.140 305.5 1.866 C022coco-2A-WBDE-salt 25336 1.298 302.8 2.143 C022coco-2B-WBDE 21355 1.065 303.5 1.755 C022coco-2B-WBDE-salt 18089 0.874 303.9 1.438 C022coco-3-WBDE 169043 9.698 302.6 16.024 C022coco-3-WBDE-salt 175800 10.093 304.5 16.573 C032coco-2A-WBDE 50912 2.793 302 4.624 C032coco-2A-WBDE-salt 45798 2.494 302.8 4.118 C032coco-2B-WBDE 21357 1.065 301 1.769 C032coco-2B-WBDE-salt 21918 1.098 300.7 1.826 C032coco-3-WBDE 156865 8.986 303.9 14.784 C032coco-3-WBDE-salt 166676 9.559 304.5 15.697
2A (One Step Base Transesterification), 2B (Two Step Base Transesterification) and 3 (Base
Neutralisation One Step Base Transesterification) are synthetic methods for biodiesel production
used in this research (refer to chapter 4).
Chapter 5 Chemical and Physical Analysis of Biodiesel
116
5.2.2.3 Discussion
The ester content in biodiesel from waste oil and coconut oil is quantified as a single
component unlike Gas Chomatography. The analytical standards used are: methyl
oleate and ethyl laurate in biodiesle from coconut oil and methyl oleate and ethyl
oleate in waste oil biodiesel. The esters of the fatty acid in the lipid raw material will
be present in similar percentage composition as its fatty acids in oil. The
transesterification of all fatty acids into esters occur proportionately which makes it
correct to quantify an ester and use it for comparing synthetic method of biodiesel
production. These standards have been used to determine the most efficient method of
producing biodiesel.
Methanol and ethanol as solvents cannot be used for comparative purposes as they
both have different rate of reaction with the catalyst (acidic and alkali) for biodiesel
production
Methyl Esters
Table 5.21 Percentage Concentration of Methyl Esters Analysed by GPC
Methyl ester Method Range (mg/ml) Median (mg/ml)
Waste oil (Methyl
oleate)
1 22.55-39.85 37.99
Coconut oil (Methyl
laurate)
1 27.50-28.48 28.05
2A 25.36-28.54 27.53
2B 23.12-27.81 26.72
Chapter 5 Chemical and Physical Analysis of Biodiesel
117
Figure 5.11 Percentage of Methyl Laurate in Coconut Oil Methyl Ester (GPC)
The table above discusses methyl esters from coconut oil and waste oil produced from
different esterification methods. For waste oil the major component quantified was
Methyl oleate and Methyl laurate in coconut oil.
Similar to results obtained from Gas Chromatography analysis, all synthetic method
were found to be of similar effectiveness with slight variation relative to each other.
Method 1 had the highest percentage median, followed by 2A than synthetic method
2B.
Lower production of ester in methodology 2A (one step base transesterfication) and
2B (two step base transesterification) resulted from formation of soap due to presence
of high free fatty acid content in lipid feedstock prior to transesterification reaction
also hindered the reaction. Whereas in method 1, high FFA content was pretreated
with acid catalyst and all products (water) were removed by washing with alcohol
before tranesterification. This step made the lipid feedstock more ready for
27.53
26.72
28.05
26
27
27
28
28
29
Est
er C
onte
nt (
%)
2A 2B 1
Biodiesel Synthetic Methods
Ester Content of Coconut Oil Methyl Esters
Chapter 5 Chemical and Physical Analysis of Biodiesel
118
transesterification reaction as the catalyst would react with more glycerides and
convert them into ester.
Comparing method 2A and 2B, 2A was found to be the better method. Partial addition
of catalyst mixture hinders higher ester formation.
Ethyl Esters
Table 5.22 Percentage Concentration of Ethyl Esters Analysed by GPC
Ethyl ester Method Range (mg/ml) Median (mg/ml)
Waste oil (Ethyl
oleate)
3 17.95-31.62 24.37
Coconut oil (Ethyl
laurate)
3 14.78-26.14 17.04
2A 0.73-1.82 1.96
2B 1.36-4.62 1.61
Figure 5.12 Percentage of Ethyl Laurate in Coconut Oil Ethyl Ester (GPC)
2.24 2.36 1.59 1.58
18.25 17.11
0.00
5.00
10.00
15.00
20.00
Est
er C
onte
nt (
%)
2A
2A sa
lt 2B
2B sa
lt 33
salt
Biodiesel Synthetic Methods
Ester Content of Coconut Oil Ethyl Esters
Chapter 5 Chemical and Physical Analysis of Biodiesel
119
The table above clearly indicates that methods 3 is a better method to use for ethyl
ester production. Relatively, method 2A was found to be better than 2B as also seen in
methyl ester analysis.
It was also observed that the samples washed with salt had greater concentration of
ethyl laurate as compare to samples washed with distilled water.
Methyl Ester versus Ethyl Ester
When comparing the analysis of both esters from the sample oil, it was observed that
the quantity of methyl esters were greater than its ethyl esters under the same
synthetic method and analysis condition. This was observed as the solubility of
methanol with oil is better than ethanol and oil.
When biodiesel was produced from the same type of sample oil (and keeping the
synthetic methods and analysis conditions unaltered), methyl esters were found to be
formed in greater quantity than ethyl esters. This is primarily due to oil being more
miscible in methanol than with ethanol.
The catalyst mixture (bound to the alcohol) is able to interact and give a faster
reaction time, which in turn promotes a greater yield.
In ethanol the oil is less miscible, thus there is less reactants available in a reactive
state. The result is a reduced yield.
Chapter 5 Chemical and Physical Analysis of Biodiesel
120
5.3 MONO-, DI- AND TRIGLYCERIDES (FREE AND
TOTAL GLYCERIDES)
5.3.1 Gas Chromatography
5.3.1.1 Methodology102
Sample preparation
Accurately weighed 100mg of biodiesel sample in a 10ml glass vial. To this 80µl of
internal standard 1 (1mg/ml butanetriol), 100µl of internal standard 2 (8mg/ml 1,2,3-
tricaproylglycerol) and 100µl of derivatising agent: N-methyl, N-
trimethylsilyltrifluoroacetamide (MSTFA) was added using micropipettes. Internal
standard 1 was intended for free glycerol determination and internal standard 2 was
for determining mono-,di- and triglycerides. The vial was quickly closed and shaken
vigorously then left at room temperature for 45minutes before adding 8ml heptane to
it. 5µl of this was then analyzed in gas chromatography instrument equipped with FID
detector. All glassware was dry and clean before use and contact to moisture was
avoided.
Preparation of standards and internal standards
Internal standard 1 (IS #1) (1mg/ml): 50mg of 1,2,4 butanetriol was dissolved in
pyridine and made up to the mark in a 50ml glass stoppered volumetric flask. Inverted
the flask to ensure homogenous mixing of solution.
Chapter 5 Chemical and Physical Analysis of Biodiesel
121
Internal standard 2 (IS #2) (8mg/ml): 80mg of 1,2,3-tricaprroylglycerol was
dissolved in a 10ml glass stoppered volumetric flask and made up o the mark with
pyridine. Inverted the flask to ensure homogenous mixing of solution.
Glycerol (0.5mg/ml): dissolved 50mg of glycerol in a 10ml volumetric and made up
to the mark with pyridine. 1 ml of this solution was transferred into another 10ml
glass stoppered volumetric flask and diluted up to the mark. Inverted the flask to
ensure homogenous mixing of solution.
Glyceride (5mg/ml): Prepared 5mg/ml solutions of mono, di and triglyceride
standards. Lauric acid glycerides and oleic acid glycerides were used to prepare
standards for coconut oil and waste oil. 50mg of each glycerides were weighed out
separately in 10ml glass stoppered volumetric flasks and made up to the mark with
pyridine. Inverted each flask to ensure homogenous mixing of solution.
Calibration solutions
Composition of glycerides and internal standards was mixed to prepare the calibration
solutions in 10ml glass vials. The volumes of each solution are given in the table
below.
Table 5.23 Glycerides Calibration solutions for contaminants in biodiesel from
waste oil (GC-FID)
Vial 1 Vial 2 Vial 3 Vial 4
µl of glycerol solution 10 40 70 100
µl of monolein solution* 50 120 190 250
µl of diolein solution* 10 40 70 100
µl of triolein solution* 10 30 60 80
µl of IS #1 solution 80 80 80 80
µl of IS #2 solution 100 100 100 100
• mono-, di- and trilauric solutions were used when preparing calibration solution for contaminants in coconut oil .
Chapter 5 Chemical and Physical Analysis of Biodiesel
122
To each of the four calibration solution vials, 100µl of derivatising agent MSTFA was
added using a micro pipette and vigorously shaken before storing it at room
temperature for 45 minutes for completion of derivatisation reaction. 8 ml of heptane
was then added to each vial and homogenously mixed. The derivatised calibration
solutions are only stable for a few hours thus freshly prepared samples were analyzed
quickly using gas chromatography.
Chromatographic analysis
The derivatised samples and calibration solution were ananlysed using gas
chromatography instrument, clarus 500, equipped with FID detector. The injection
syringe was made free of any contamination by washing it several times with heptane
and the sample to be injected. The conditions for analysis are given in the table below.
Table 5.24 Gas Chromatography (FID) Instrumentation Condition for Biodiesel
Contaminants Analysis
Column: ATTM –5MS(Alltech)
30m x 0.25mm ID x 0.25µm film.
Oven: Initial temperature: 50°C,
Initial hold: 1.00 min
Equiliberation time: 2.00min
Ramp 1: 15.0 °C/min to 180°C, hold for 10.00 min
Ramp 2: 7.0 °C/min to 230°C, hold for 0.00 min
Ramp 3: 10.0 °C/min to 350°C, hold for 5.00 min
Total run time: 33.80 min
Carrier: Nitrogen at 10.8 psi
Injector: Split mode
Temperature: 200°C
Injection volume 5 µl
Detector:
Flame Ionization Detector
Temperature: 300°C
Spilt flow ratio: 100:1
Split flow rate: 60.1 ml/min
Chapter 5 Chemical and Physical Analysis of Biodiesel
123
5.3.1.2 Results and Dicussion
Quantification of bound and free glycerides could not be carried out as the
derivatising agent degraded. The peaks of the derivatising agent observed in the
chromatograms overlapped the peaks of the sample and the standards used in this
method. Thus the quantification of the bound and free glycerides was inhibited. It is
recommended to use other appropriate derivatising agent.
Derivatising Agent - MSTFA
MSTFA is a better derivating agent over other common silylating agents like BSTFA
as it requires no heating and complete derivatisation reaction occurs at room
temperature. Inert storage conditions were required for this reagent. MSTFA reagent
bottle was store in a desicator purged with nitrogen gas (N2) and the bottle was always
purged with N2 gas whenever it was opened and before recapping. Despite such
precautionary measures MSTFA degraded, resulting in numerous peaks through out
the chromatogram. MSTFA is also moisture sensitive and is unsuitable to be used for
analysis in a very humid environment. Such chemicals require special chambers (inert
gas) for sample preparation, thus is not recommended for use in tropical countries
without appropriate facilities.
Chapter 5 Chemical and Physical Analysis of Biodiesel
124
5.3.2 Gel Permeation Chromatography
5.3.2.1 Methodology
Sample preparation
The procedure for the analysis of contaminant in biodiesel using GPC was the same as
GPC method for ester content101 determination see section 5.3.1.1. The standard
preparation for calibration were prepared according to the table below
Standard preparation
The respective glyceride standards were quantified in coconut oil and waste oil.
Monolien, Diolien, and Triolien standards represented the glycerides in waste oil.
Monolauric, Dilauric and trilauric standards represented the glyceride in coconut
oil. These standards were prepared in different concentrations (table 5.25 to table 5.30)
and 10ul of each were analyzed in a GPC system described below.
A calibration curve was plotted using the peak area of these standards versus its
concentration. It was used to determine the concentration of glycerides in the
respective biodiesel samples synthesized from coconut and waste oil.
Figure 5.13 Calibration Curve of Trilauric Acid
y = 19166x + 70.615
R2 = 0.9927
0
200
400
600
800
1000
1200
0.0000 0.0100 0.0200 0.0300 0.0400 0.0500 0.0600
Concentration (mg/ml)
Are
a (V
*sec
)
Chapter 5 Chemical and Physical Analysis of Biodiesel
125
Table 5.25 Peak Area versus Concentration of Trilauric Acid
Concentration (mg/ml) Peak Area (V*sec)
0.0061 208
0.0177 384
0.0285 630
0.0387 779
0.0482 1020
Figure 5.14 Calibration Curve of Dilauric Acid
Table 5.26 Peak Area versus Concentration of Dilauric Acid
Concentration (mg/ml) Peak Area (V*sec)
0.0061 117
0.0236 618
0.0400 1334
0.0552 1815
0.0696 2390
y = 36173x - 152.47
R2 = 0.9962
0
500
1000
1500
2000
2500
3000
0.0000 0.0200 0.0400 0.0600 0.0800
Concentration (mg/ml)
Are
a (V
*sec
)
Chapter 5 Chemical and Physical Analysis of Biodiesel
126
Figure 5.15 Calibration Curve of Monolauric Acid
Table 5.27 Peak Area versus Concentration of Monolauric Acid
Concentration (mg/ml) Peak Area (V*sec)
0.0306 1577
0.0708 2387
0.1084 3347
0.1436 4386
0.1767 5280
Figure 5.16 Calibration Curve of Trioliec Acid
y = 39842x - 165.89R2 = 0.9946
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0.0000 0.0100 0.0200 0.0300 0.0400 0.0500 0.0600
Concentration (mg/ml)
Are
a (V
*sec
)
y = 25704x + 670
R2 = 0.9951
0
1000
2000
3000
4000
5000
6000
0.0000 0.0200 0.0400 0.0600 0.0800 0.1000 0.1200 0.1400 0.1600 0.1800 0.2000
Concentration (mg/ml)
Are
a (V
*sec
)
Chapter 5 Chemical and Physical Analysis of Biodiesel
127
Table 5.28 Peak Area versus Concentration of Trioliec Acid
Concentration (mg/ml) Peak Area (V*sec)
0.0061 101
0.0177 561
0.0285 903
0.0387 1344
0.0482 1808
Figure 5.17 Calibration Curve of Dioliec Acid
Table 5.29 Peak Area versus Concentration of Dioliec Acid
Concentration (mg/ml) Peak Area (V*sec)
0.0061 117
0.0236 830
0.0400 1873
0.0552 2685
0.0696 3595
y = 55425x - 336.47R2 = 0.9948
0
500
1000
1500
2000
2500
3000
3500
4000
0.0000 0.0200 0.0400 0.0600 0.0800
Concentration (mg/ml)
Are
a (V
*sec
)
Chapter 5 Chemical and Physical Analysis of Biodiesel
128
Figure 5.18 Calibration Curve of Monoliec Acid
Table 5.30 Peak Area versus Concentration of Monoliec Acid
Concentration (mg/ml) Peak Area (V*sec)
0.0305 1012
0.0708 2472
0.1084 3766
0.1436 4863
0.1767 6129
0.2125 7561
y = 35486x - 91.964
R2 = 0.9987
0
1000
2000
3000
4000
5000
6000
7000
8000
0 0.05 0.1 0.15 0.2 0.25
Concentration (mg/ml)A
rea
(V*s
ec)
Chapter 5 Chemical and Physical Analysis of Biodiesel
129
5.3.2.2 Results
Mono, Di and Tri-glyceride in Waste Oil Methyl Esters
Table 5.31 Concentration of Bound Glycerides in Waste Oil Biodiesel Samples
Sample Glycerides
peak area
(V*sec)
B
Mass of
sample
A Concentration
of Bound
Glycerides
(mg/ml)
[(A x 5ml)/B] x
100
(%)
W001p-1-WBDM 14869 303.5 0.422 - 0.377 0.695 – 0.622
W021p-1-WBDM 23014 304.1 0.651 - 0.582 1.071 – 0.957
W031p-1-WBDM 5920 303.3 0.169 - 0.153 0.279 – 0.252
W002s-1-WBDM 29066 304.7 0.822 - 0.734 1.348 – 1.204
W022s-1-WBDM 23544 300.4 0.666 - 0.595 1.109 – 0.991
W032s-1-WBDM 14507 300.9 0.411 - 0.368 0.684 – 0.612
W003s-1-WBDM 24666 301.7 0.698 - 0.623 1.156 – 1.033
W023s-1-WBDM 36021 304.9 1.018 - 0.909 1.669 – 1.489
W033s-1-WBDM 40440 301.4 1.142 - 0.019 1.895 – 1.691
Note: all samples were prepared using Acid pretreatment methodology
Chapter 5 Chemical and Physical Analysis of Biodiesel
130
Mono, Di and Tri-glyceride in Coconut Oil Methyl Esters
Table 5.32 Concentration of Bound Glycerides in Coconut Oil Biodiesel Samples
Sample Glycerides
peak area
(V*sec)
B
Mass of
sample
A
Concentration
of Bound
Glycerides
(mg/ml)
[(A x 5ml)/B] x
100
(%)
C001coco-2A-WBDM 36949 301.6 1.411 – 1.924 2.340 – 3.190
C001coco-2B-WBDM 59862 305.1 2.303 – 3.120 3.774 – 5.113
C001coco-1-WBDM
C021coco-2A-WBDM 51703 300.5 1.985 – 2.694 3.304 – 4.482
C021coco-2B-WBDM 79874 302.7 3.081 – 4.164 5.090 – 6.878
C021coco-1-WBDM
C031coco-2A-WBDM 25788 304.8 0.977 – 1.342 1.603 – 2.201
C031coco-2B-WBDM 119056 302.8 4.606 – 6.208 7.605 – 10.251
C031coco-1-WBDM
C002coco-2A-WBDM 146220 302.5 5.663 – 7.625 9.360 – 12.604
C002coco-2B-WBDM 267621 304.3 10.386 – 13.960 17.065 – 22.937
C002coco-1-WBDM
C022coco-2A-WBDM 47218 300.7 1.811 – 2.460 3.011 – 4.090
C022coco-2B-WBDM 111217 301.3 4.301 – 5.799 7.137 – 9.624
C022coco-1-WBDM 5979 304.9 0.207 – 0.308 0.339 – 0.506
C032coco-2A-WBDM 14026 301.8 0.520 – 0.728 0.861 – 1.206
C032coco-2B-WBDM 3084 302.8 0.094 – 0.157 0.155 – 0.260
C032coco-1-WBDM 10960 301.3 0.400 – 0.568 0.664 – 0.943
Chapter 5 Chemical and Physical Analysis of Biodiesel
131
Mono, Di and Tri-glyceride in Waste Oil Ethyl Esters
Table 5.33 Concentration of Bound Glycerides in Waste Oil Biodiesel Samples
A
Concentration of
Bound Glycerides
(mg/ml)
B
Mass of
sample
(mg)
(A x 5ml)/B] x 100
(%)
W001p-3-WBDE 134994 3.807 – 3.392 302.6 6.290 – 5.605
W021p-3-WBDE 358596 10.108 – 9.005 301.4 16.768 – 14.938
W031p-3-WBDE 381059 10.741 – 9.568 304.9 17.614 – 15.691
W002s-3-WBDE 319819 9.015 – 8.031 301.6 14.946 – 13.315
W022s-3-WBDE 441287 12.438 – 11.080 302.8 20.538 – 18.296
W032s-3-WBDE 464014 13.079 – 11.651 302.0 21.653 – 19.289
W003s-3-WBDE 207861 5.860 – 5.221 303.9 9.642 – 8.590
W023s-3-WBDE 199744 5.631 – 5.018 305.0 9.232 – 8.226
W033s-3-WBDE 187175 5.277 – 4.702 303.4 8.697 – 7.749
Chapter 5 Chemical and Physical Analysis of Biodiesel
132
Mono, Di and Tri-glyceride in Coconut Oil Ethyl Esters
Table 5.34 Concentration of Bound Glycerides in Coconut Oil Biodiesel Samples
Sample Ethyl Laurate
peak area
A Concentration of
Bound Glycerides (mg/ml)
B Mass of sample (mg)
[(A x 5ml)/B] x 100 (%)
C001coco-2A-WBDE 145630 5.640 – 7.595 301.8 9.343 – 12.582 C001coco-2A-WBDE-salt 153938 5.963 – 8.028 305.8 9.749 – 13.127
C001coco-2B-WBDE 136863 5.299 – 7.137 301.6 8.784 – 11.832 C001coco-2B-WBDE-salt 137703 5.331 – 7.181 302 8.826 – 11.889
C001coco-3-WBDE 42896 1.643 – 2.234 305.2 2.691 – 3.660 C021coco-2A-WBDE 142429 5.515 – 7.428 302.6 9.113 – 12.273
C021coco-2A-WBDE-salt 139779 5.412 – 7.289 304.7 8.881 – 11.962 C021coco-2B-WBDE 142005 5.499 –7.406 302.5 9.089 – 12.241
C021coco-2B-WBDE-salt 144977 5.614 – 7.561 303.4 9.252 – 12.460 C021coco-3-WBDE 59299 2.281 – 3.090 301.4 3.7840 – 5.126
C021coco-3-WBDE-salt 58722 2.258 – 3.060 302.6 3.732 – 5.057 C031coco-2A-WBDE 147954 5.730 – 7.716 305.5 9.378 – 12.628
C031coco-2A-WBDE-salt 137351 5.317 – 7.163 302.9 8.778 – 11.824 C031coco-2B-WBDE 152523 5.908 – 7.954 305.5 9.670 – 13.019
C031coco-2B-WBDE-salt 162474 6.295 – 8.474 302.9 10.391 – 13.987 C031coco-3-WBDE 76917 2.966 – 4.020 302.9 4.8970 – 6.619
C031coco-3-WBDE-salt 81894 3.160 – 4.269 301.2 5.246 – 7.087 C002coco-2A-WBDE 146290 5.665 – 7.629 302.2 9.373 – 12.623
C002coco-2A-WBDE-salt 147928 5.729 – 7.715 304.1 9.420 – 12.684 C002coco-2B-WBDE 144717 5.604 – 7.547 302.5 9.263 – 12.474
C002coco-2B-WBDE-salt 143282 5.548 – 7.472 302.3 9.177 – 12.359 C002coco-3-WBDE 80573 3.109 – 4.200 304.3 5.108 – 6.902
C002coco-3-WBDE-salt 73277 2.825 – 3.820 302.3 4.672 – 6.318 C022coco-2A-WBDE 144116 5.581 – 7.516 305.5 9.134 – 12.301
C022coco-2A-WBDE-salt 142891 5.533 – 7.452 302.8 9.136 – 12.305 C022coco-2B-WBDE 145315 5.627 – 7.578 303.5 9.271 – 12.485
C022coco-2B-WBDE-salt 146767 5.684 – 7.654 303.9 9.352 – 12.593 C022coco-3-WBDE 74611 2.877 – 3.889 302.6 4.753 – 6.426
C022coco-3-WBDE-salt 74060 2.855 – 3.861 304.5 4.688 – 6.339 C032coco-2A-WBDE 136399 5.280 – 7.113 302 8.743 – 11.777
C032coco-2A-WBDE-salt 120304 4.654 – 6.273 302.8 7.685 – 10.359 C032coco-2B-WBDE 134972 5.225 – 7.039 301 8.680 – 11.692
C032coco-2B-WBDE-salt 140388 5.436 – 7.321 300.7 9.038 – 12.174 C032coco-3-WBDE 91767 3.544 – 4.784 303.9 5.831 – 7.872
C032coco-3-WBDE-salt 91628 3.539 – 4.777 304.5 5.811 – 7.844
Chapter 5 Chemical and Physical Analysis of Biodiesel
133
5.3.2.3 Discussion
When using standards which are glycerides (mono-, di- and triglycerides) of high
purity, the peaks distinctly separates but this does not occur in biodiesel samples.
However, the mono-, di- and triglycerides overlap each other forming a clump of
peaks with slight bumps indicating each group of glycerides, see figure below. The
components are separated according to their molecular weight, eluting in a descending
order.
The negative peaks can be accounted for as components with the refractive index (RI)
less than that of the mobile phase (THF). These contaminants are likely to be ethanol,
methanol or water that was present in the reaction mixture.
The column used separates small organics (components of interest in biodiesel sample
analysed) with molecular weight exclusion limit between 100 - 3K. The molecular
weights of the components of interest to be analysed in coconut oil and waste oil
biodiesel are given in the table 5.35.
Table 5.35 Molecular weights of components in biodiesel samples analysed
Acylglyceride Esters
Monoglyceride Diglyceride Triglyceride Methyl Ethy l
Coconut oil (Lauric
acid/ester) 274.4 456.7 639.0 214.3 228.4
Waste oil
(Oleic acid/ester) 356.5 621.0 885.4 296.5 310.5
According to the column specification more resolution of peaks were expected.
However, the cluster of peaks observed was unavoidable with the existing setup. This
could be corrected by connecting more similar columns or columns with larger pore
size in series. In a research conducted by Arzamendhi G, et. al.103 resolution of
Chapter 5 Chemical and Physical Analysis of Biodiesel
134
glyceride (contaminant) peaks in biodiesel was effective when using three columns in
series. Two columns of which were similar with the third one having a smaller pore
size.
The results obtained by analyzing the synthesized biodiesel samples were acceptable
and quantification of the characterized group (total glyceride) was possible.
Figure 5.19 GPC chromatogram of Coconut oil Biodiesel Sample
In coconut oil biodiesel, the glycerides are quantified as lauric acid: monolauric acid,
dilauric acid and trilauric acid and in waste oil biodiesel the glycerides are represented
as oleic acid glycerides. Its quantification is carried out using calibration method of
glycerides described in the methodology. Percentages of total glycerides are given as
a range which encompasses the minimum and maximum percentage that could be
present in the sample. The minimum percentage is calculated based on the calibration
of triglycerides which has the lowest response factor relative to its esters. The
maximum range is deduced from monoglycerides calibration with the highest
response factor relative to its esters. See table 5.35.
Triglyceride
Diglyceride
Monoglycerides
Chapter 5 Chemical and Physical Analysis of Biodiesel
135
Table 5.36 Relative Response Factors of Glycerides to Esters.
Glycerides Relative to Ester Relative Response Fact or
Methyl Oleate 0.308 Trioleic Acid
Ethyl Oleate 0.310
Methyl Oleate 0.356 Dioleic Acid
Ethyl Oleate 0.359
Methyl Oleate 0.614 Monoleic Acid
Ethyl Oleate 0.619
1.571 Trilauric Acid Methyl Laurate
Ethyl Laurate 2.134
Methyl Laurate 0.884 Dilauric Acid
Ethyl Laurate 1.201
Methyl Laurate 2.375 Monolauric Acid
Ethyl Laurate 3.225
It should be noted that the percentage of glycerides are represented as the major fatty
acid component in the lipid raw material of biodiesel. Thus, these results are
comparable only within this thesis.
Figure 5.20 Percentage Concentration of Glyceride content in Coconut oil Methyl
Esters
4.02
7.99
0.61
012345678
Bou
nd G
lyce
rides
(%
)
2A 2B 1
Biodiesel Synthetic Methods
Glyceride Content of Coconut Oil Methyl Esters
Chapter 5 Chemical and Physical Analysis of Biodiesel
136
Acid pretreatment followed by base transesterification production process contains
the least glycerides relative to other biodiesel synthetic methods. These results were
as expected as free fatty acids are hydrolysed leaving high concentration of glycerides
for the next base transesterification process. As free fatty acids are removed, the
alkaline catalysts react with the glycerides to form esters in presences of alcohol.
Imperatively, methods 2A and 2B both result in higher glyceride content in the
biodiesel samples. This is due to high free fatty acid content in the lipid raw material
(coconut oil). Straight base tranesterification is this case would result is high
concentration of unreacted glycerides as seen. In method 2B where the phases (upper
biodiesel and lower glycerol layer) are allowed to separate and removed (intermediate
process), transesterification reaction is slowed down. In the intermediate process the
reaction vessel cools, separation occurs and vessel is reheated after adding the
remaining catalytic mixture. This reduces the efficiency of glyceride conversion to
esters.
Figure 5.21 Percentage Concentrations of Glycerides in Coconut Oil Ethyl Esters
10.77 10.49 10.71 10.96
5.31 5.68
0
2
4
6
8
10
12
Bou
nd G
lyce
rides
(%
)
2A
2A sa
lt 2B
2B sa
lt 33
salt
Biodiesel Synthetic Methods
Glyceride Content of Coconut Oil Ethyl Esters
Chapter 5 Chemical and Physical Analysis of Biodiesel
137
As observed in methyl esters samples of biodiesel, the percentage of glycerides in
ethyl ester samples produced from 2A and 2B was high relative to synthetic method 3
(Base Neutralisation – one step bse transesterification).
Method 3 had excess alkaline catalyst to neutralize the free fatty acids present in the
lipid raw material (coconut oil). The remaining catalysts reacted with the glycerides to
form esters. It can be seen that a higher percentage of glycerides have been converted
to esters via method 3 than 2A or 2B.
Another important experiment conducted was the effect of saline water washing of
biodiesel during purification process. It is clear from the results tha saline water
washing has no effect on reducing the glyceride content in the biodiesel samples.
Figure 5.22 Using Percentage Glyceride Content to Compare Different Synthetic
Methods.
The glyceride conversion into esters is more effective using methanol as alcohol
source as compared to ethanol.
1.04 0.61
13.17
5.31
0
5
10
15
Bou
nd
Gly
cerid
e (%
)
1 3
Biodiesel Synthetic Methods
Glyceride Content in Biodiesel from Different Synthetic Methods
Waste Oil Biodiesel Coconut Oil Biodiesel
Chapter 5 Chemical and Physical Analysis of Biodiesel
138
Method 3 - Base Neutralization (excess base), one step base transesterfication and
method 1 – Acid Pretreatment, one step base transesterification were found to be the
better methods for higher conversion of glycerides into esters. The effect of high free
fatty acid is seen in the figure above where the glyceride contents of Waste oil
biodiesel and coconut oil biodiesel is compared. Waste oil used to prepare the
biodiesel sample has a higher free fatty acid content as compare to coconut oil (lipid
source for coconut oil esters). In the samples from both the methods (1and 3) waste
oil has a lower conversion of glycerides to esters than coconut oil with a lower free
fatty acid value.
Chapter 5 Chemical and Physical Analysis of Biodiesel
139
5.3.3 Gas chromatography – Mass Spectrometry
5.3.3.1 Methodology
Sample preparation
1 µl of biodiesel sample was diluted in n-pentane and 1 µl of this was injected using
an auto-sampler, which was purged before each batch of analysis, and the syringe was
washed thoroughly with the solvent and the sample mixture.
Table 5.37 GCMS Instrument Condition for Analysis of Biodiesel Samples
Column: BP 20 (SGE)
30m x 0.25mm ID x 0.25µm film.
Oven: Initial temperature: 100°C,
Initial hold: 5.00 min
Equiliberation time: 0.50min
Ramp 1: 5.0 °C/min to 220°C, hold for 25.00 min
Total run time: 54.00 min
Carrier: Nitrogen at 0.9 ml/min
Injector: Split mode
Temperature: 250°C
Injection volume 1 µl
Detector: Mass Spectrometer Detector 1.5KV
Mass range 41 m/z – 450m/z
Spilt flow ratio: 25:1
Chapter 5 Chemical and Physical Analysis of Biodiesel
140
5.3.3.2 Results
Table 5.38 Mass Spectral Data of Fatty Acid Esters Analysed.
Samples M + Mass Spectral data
(m/z)
Esters
214 = [C13H26O2]+ Methyl laurate (C 12)
242 = [C15H30O2]+ Methyl tetradecanoate (C 14)
270 = [C17H34O2]+ Methyl hexadecanoate (C 16)
298 = [C19H38O2]+ Methyl octadecanoate (C 18)
Coconut oil methyl
ester
326 = [C21H42O2]+ Methyl Eicosanoate (C 20)
354 = [C23H46O2]+ Methyl docsanoate (C 22)
228= [C14H28O2]+ Ethyl laurate (C 12)
256 = [C16H32O2]+ Ethyl tetradecanoate (C 14)
284 = [C18H36O2]+ Ethyl hexadecanoate (C16)
312 = [C20H40O2]+ Ethyl octdecanoate (C 18)
340 = [C22H44O2]+ Ethyl eicosanoate(C 20)
Coconut oil ethyl
ester
368 = [C24H48O2]+ Ethyl docsanoate (C 22)
Waste oil methyl 270 = [C17H34O2]+ Methyl hexadecanoate (C 16)
ester 298 = [C19H38O2]+ Methyl octadecanoate (C 18)
326 = [C21H42O2]+ Methyl Eicosanoate (C 20)
354 = [C23H46O2]+ Methyl docosanoate (C 22)
382 = [C25H50O2]+ Methyl tetracosanoate (C 24)
Waste oil ethyl ester 284 = [C18H36O2]+ Ethyl hexadecanoate (C16)
312 = [C20H40O2]+ Ethyl octdecanoate (C 18)
340 = [C22H44O2]+ Ethyl eicosanoate(C 20)
368 = [C24H48O2]+ Ethyl docsanoate (C 22)
396 = [C26H52O2]+ Ethyl tetracosanoate (C 24)
Branched chain fatty acids are not included.
Chapter 5 Chemical and Physical Analysis of Biodiesel
141
5.4 PHYSICAL ANALYSIS
5.4.1 Viscocity
5.4.1.1 Methodology
Viscosity of biodiesel samples produced using the various lipid raw materials studied
in chapter 3 was obtained. This was measured using a HAAKE model viscotester
VT6/7 L with L1 (spindle No.1 for low viscosity test fluids) at 200 rpm and 60 rpm.
Five readings for each sample were taken and the average was noted.
5.4.1.2 Results
Table 5.39 Viscosity of biodiesel samples investigated
Samples Viscosity (mPas) @ 27.5 ºC
Coconut oil methyl ester @ 200 rpm 8-9
Coconut oil ethyl esters @ 60 rpm 80-81
Waste oil methyl esters @ 200 rpm 12-14
Waste oil ethyl esters @ 60 rpm 85-87
Relatively the ethyl esters are more viscous than methyl esters as seen. However, the
waste oil esters are relatively more viscous than coconut oil esters. There are higher
percentage composition of longer chain fatty acids in waste oil (C20 and higher)
which are more viscous than short chain fatty acids (C8 and higher) in coconut oil.
Chapter 5 Chemical and Physical Analysis of Biodiesel
142
5.5 IN SUMMARY
Comparison of Analytical Methods
The chromatography analytical techniques employed to determine the quality of
biodiesel includes Gas Chromatography (GC) and Gel Permeation Chromatography
(GPC). Using these techniques the contaminats and ester content can be successfully
determined using respective standard calibration. The suitability of these analytical
techniques to be incorporated as a quality control measure in our region are
determined by looking at the following factors.
Gas Chromatography
Quantification of glycerides (contaminants) and esters are done separately with
different sample preparation and instrumentation methods. Each analysis also used
different columns.
Chapter 5 Chemical and Physical Analysis of Biodiesel
143
Table 5.40 Advantages and Disadvantages of Analysing Biodiesel using GC
Sample
Preparation
Glyceride analysis
Tedious in glyceride quantification.
Requires 45 min of sample derivatisation before dilution.
Derivatising agent is very sensitive to humidity, thus proper storage
procedures need to be followed to prevent degradation of agent.
Derivatised samples are only stable for 2-3 hours.
Ester analysis
Simple dilution of sample.
In both analysis the internal standard regent is pyridine (enhances
stability of standard) and the dilution regent is heptane.
Analysis Glyceride analysis time was 33 minutes and ester run time was 25
minutes.
Data Analysis For both analysis:
Every single component in the sample is quantified.
Identification of the different peak is required in order to group them as
esters or contaminants, then only the total percentage of each in the
sample can be denoted.
Gel Permeation Chromatography
Quantification of each lipid or ester component in the biodiesel sample is impossible
with GPC103. However it is useful in characterising the biodiesel components. This is
greatly an efficient and acceptable method as the standardisation of biodiesel requires
quantification of characterised component rather than the quantification of a specific
component in the biodiesel fuel. For example, according to the Australian Fuel
Quality Standard for biodiesel the specification requires total ester content but not a
specific ester composition, which can be ethyl palmitate, methyl stearate, etc.
Similarly, quantification of total and free glycerol content is required, not mono
palmitic acid, di stearic acid, etc.
Chapter 5 Chemical and Physical Analysis of Biodiesel
144
The importance of quantifying specific components should not be overlooked. Each
component has its own properties and influences the fuel properties of biodiesel when
present is large quantities.
Quantification of glycerides and esters were of homogenous nature. Both parameters
were determined in a single run with the same sample preparation and instrumentation
conditions. This method of analysis can also be used during transesterication reaction
process after diluting and neutralising the samples. Water and alcohol as contaminant
can be analysed together with acylglycerides.
Table 5.41 Advantages and Disadvantages of Analysing Biodiesel using GPC
Sample
Preparation
In both analyses, simple dilution of sample with Tetrahydrofuran was
carried out. No other regents were required.
Analysis Analysis time was 22 minutes.
Data Analysis Glyceride constituents appeared as an overlap of peak that was
quantified as contaminant. The well separated peaks of esters
appeared at a later retention time from which the ester content was
deduced. It required less time to interpret data.
Chapter 6 Conclusion
145
6 CHAPTER 6 CONCLUSION AND
RECOMMENDATION
Raw material analysis
The four lipid sources were analysed for free fatty acid content, iodine value (degree
of saturation), phosphorus and moisture content.
Lipid Source Iodine Value Free Fatty Acid Phosphoru s
content
Moisture
Content
Canola 111.02-132.92 < 1% < 0.03% < 1%
Soybean 116.70-134.47 < 1% < 0.03% < 1%
Waste 40.90-70.03 > 1% Below detection < 1%
Coconut 6.08-9.26 > 1% Below detection < 1%
Coconut oil and waste oil were identified to be the most suitable lipid source for
biodiesle production in Fiji. They are both :
available locally in abundance and accessible,
affordable ,
in consistent supply.
The high FFA content in coconut and waste oil are easily overcome by pre-treatment
procedures like acid pre-treatment process or excess base transesterification process
as investigated in this project. Moisture content of all lipids were less than 1%, thus
considered negligible for transesterification reaction.
Chapter 6 Conclusion
146
The other two tests denote the oxidative stability of the corresponding esters produced
from these lipids. Biodiesel from coconut oil should be the most stable followed by
waste, canola and soybean oil.
Pretreatment Methods
The most suitable catalyst for methanolysis and ethanolysis process was 1% sodium
hydroxide and 0.5% potassium hydroxide, respectively.
When comparing molar ratio of alcohol/FFA and catalyst amount in Acid pre-
treatment process, a 20:1 (methanol/FFA) molar ratio with 10% catalyst was the
most suitable mixture for methanolysis. For ethanolysis this was 40:1 (ethanol/FFA)
with 10% catalyst mixture.
Biodiesel Synthetic Methods
Method 1- Acid Pretreatment – One step base transesterification
Methanolysis using method 1 had good separation of layers and no soap formation.
This method had the lowest loss of water solubles during purification with median
loss values of 16.44% for coconut oil biodiesel and 18.61% for waste oil biodiesel.
Coconut oil methyl ester had greater yield with 96.22% (as methyl laurate) percentage
esters and waste oil methyl ester had 28.21% (as methyl oleate). The bound glyceride
content of coconut oil methyl ester sample was 0.61% and waste oil methyl ester
sample had 1.04%.
Chapter 6 Conclusion
147
In Ethanolysis there was no separation of acid and lipid layers. This method was
unsuccessful.
It is recommended that for method 1 the reaction time should be increased with lipid
source containing longer chain or branched fatty acids
Method 2A - One step base transesterification
When the reaction was via methanolysis, less than 25% of water solubles were lost
during washing. One step transesterification worked best with coconut oil methyl
esters with percentage yield of 98.39% (as methyl laurate). The bound glyceride
content was found to 4.02% in coconut oil methyl esters.
For ethanolysis less than 56% of water solubles were lost during washing. Separation
of phases became difficult after first few washing. A lot of soap produced. The
percentage of esters was 94.26% (as ethyl laurate), 4.13% less than the methyl esters
prepared using similar method. The bound glyceride content was found to 10.77% in
coconut oil ethyl esters.
It is recommended that method 2A not be used for biodiesel synthesis using lipid
sources with high FFA content. For ethanolysis, a cosolvent such as tetrahydrofuran
can be used to aid separation of the product and by product layers
Chapter 6 Conclusion
148
Method 2B - Two step Base Transesterification
Major problem during methanolysis was the high amount of soap production. Less
than 28% of water solubles were lost during washing.Two step base transesterification
had a percentage yield of 94.49% (as methyl laurate).The bound glyceride content
was found to 7.99% in coconut oil methyl esters.
The percentage ester yield obtained via ethanolysis was 93.67% (as ethyl laurate),
0.82%, less than the methyl esters prepare using similar method. There was major loss
of crude biodiesel during washing due to phase separation problems. Less than 67%
of water solubles were lost during washing. The bound glyceride content was found to
10.71% in coconut oil ethyl esters.
Method 2B is also not recommended for lipid sources with high FFA content. For
better ester conversion rates the reaction time should be increased.
Method 3 - Base Neutralisation – One Step base transesterfication.
Coconut oil ethyl ester synthesised using ethanolysis had a greater yield relative to
coconut esters synthesised using other methods (2A and 2B). the yield for coconut oil
ethyl esters was 61.56% (as ethyl laurate) and 28.46% (as ethyl oleate) for . waste oil
ethyl esters. A lot of soap was produced during washing with less than 75% water
solubles lost. The bound glyceride content of coconut oil methyl ester sample was
5.31% and waste oil methyl ester sample had 13.17% bound glyceride content.
Chapter 6 Conclusion
149
In this synthetic methodology it is recommended to use saline water washing before
normal water washing for purification process. This synthetic method can be used to
produce quality biodiesel from lipid sources with high FFA value.
Generally, one step base transesterification reaction (method 2A) is more efficient
than two step base (method 2B) transesterification reaction for both cases: Ethanolysis
and methanolysis.
Purification
Fine nozzle dispersion of water was found to be the most effective method of washing.
Salnine water is more effective in removing soap than using only distilled water.
Saline washing does not affect the ester content of biodiesel. It must be noted that the
salinity must be removed by washing with plain water before using biodiesel as fuel.
Analysis and Quantification
The ethyl esters of coconut oil and waste oil were more viscous than its methyl esters.
GPC is a better analytical technique to monitor the progress of biodiesel reaction as it
indicated the contaminants as a group of peak which can easily be quantified. The
general standards for biodiesel requires the total amount of contaminants thus this is
sufficient.
GC techniques complement GPC as it aids in providing extra quality control
information like the exact concentration/percentage of a particular fatty acid ester in
the sample. This information is vital in terms of influence on the physical properties
of biodiesel. Having a higher concentration of a branched or longer chain fatty acid
Chapter 6 Conclusion
150
ester increases the vicosity, ignition, cloud and pour point properties of the biodiesel.
See 5.1 Introduction.
Waste oil esters indicate a higher percentage in GPC compared to GC results though
the percentage of esters is represented as Methyl or ethyl oleate. This clearly indicated
the need to identify all of the ester peak in GC analysis to determine the total ester
content. In this respect GPC analysis in more preferred.
Appendix
151
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Appendix
164
APPENDIX
FREE FATTY ACID
Table A1. Free Fatty Acid and Acid Values of Soybean oil
Titer Volume
(ml)
Weight of Sample (g)
Normality of NaOH Solution
(N)
Free Fatty Acid (FFA)
% Acid Value
C001soy A 1.60 28.2088 0.1000 0.16 0.32
Oleic acid B 1.50 28.2003 0.1000 0.15 0.30
C 1.60 28.2102 0.1000 0.16 0.32
C021soy A 2.20 28.0434 0.0968 0.21 0.43
Oleic acid B 2.20 28.0451 0.0968 0.21 0.43
C 2.20 28.0710 0.0968 0.21 0.43
C031soy A 1.70 28.0337 0.0968 0.17 0.33
Oleic acid B 1.70 28.0020 0.0968 0.17 0.33
C 1.60 28.0282 0.0968 0.16 0.31
C002soy A 1.40 28.0267 0.0968 0.14 0.27
Oleic acid B 1.30 28.0221 0.0968 0.13 0.25
C 1.40 28.0050 0.0968 0.14 0.27
C022soy A 1.20 28.0895 0.0968 0.12 0.23
Oleic acid B 1.30 28.0847 0.0968 0.13 0.25
C 1.30 28.0661 0.0968 0.13 0.25
C032soy A 1.40 28.0001 0.0968 0.14 0.27
Oleic acid B 1.40 28.0020 0.0968 0.14 0.27
C 1.30 28.0282 0.0968 0.13 0.25
Where:
C001soy – brand 1, soybean oil bottle 1
C021soy – brand 1, soybean oil bottle 2
C031soy – brand 1, soybean oil bottle 3
C002soy – brand 2, soybean oil bottle 1
C022soy – brand 2, soybean oil bottle 2
C032soy – brand 2, soybean oil bottle 3
Appendix
165
Table A2. Free Fatty Acid and Acid Values of Canola oil
Titer
Volume (ml)
Weight of Sample (g)
Normality of NaOH Solution
(N)
Free Fatty Acid (FFA)
% Acid Value
C001can A 1.90 28.2234 0.1000 0.19 0.38 Oleic acid B 1..90 28.2162 0.1000 0.19 0.38
C 1.80 28.2162 0.1000 0.18 0.36 C021can A 1.70 28.0243 0.0968 0.17 0.33 Oleic acid B 1.60 28.0247 0.0968 0.16 0.31
C 1.70 28.0769 0.0968 0.17 0.33 C031can A 1.70 28.0924 0.0968 0.17 0.33 Oleic acid B 1.70 28.0696 0.0986 0.17 0.34 C 1.70 28.0812 0.0968 0.17 0.33 C002can A 2.20 28.0330 0.0968 0.21 0.43 Oleic acid B 2.30 28.0140 0.0968 0.22 0.45 C 2.20 28.0509 0.0968 0.21 0.43 C022can A 3.10 28.0062 0.0968 0.30 0.60 Oleic acid B 3.10 28.0049 0.0968 0.30 0.60 C 3.20 28.0987 0.0968 0.31 0.62 C032can A 2.20 28.0920 0.0968 0.21 0.43 Oleic acid B 2.20 28.0892 0.0968 0.21 0.43 C 2.20 28.0236 0.0968 0.21 0.43
Where: C001can – brand 1, canola oil bottle 1 C021can – brand 1, canola oil bottle 2 C031can – brand 1, canola oil bottle 3 C002can – brand 2, canola oil bottle 1 C022can – brand 2, canola oil bottle 2 C032can – brand 2, canola oil bottle 3
Appendix
166
Table A3. Free Fatty Acid and Acid Values of Coconut oil
Titer Volume
(ml)
Weight of Sample (g)
Normality of NaOH Solution
(N)
Free Fatty Acid (FFA)
% Acid Value
C001coco A 5.30 7.0178 0.2393 3.61 10.14 Lauric acid B 5.20 7.0481 0.2393 3.53 9.90
C 5.30 7.0319 0.2393 3.61 10.12
C021coco A 5.20 7.0169 0.2393 3.55 9.95 Lauric acid B 5.10 7.0383 0.2393 3.47 9.73
C 5.20 7.0113 0.2393 3.55 9.96
C031coco A 5.20 7.0445 0.2393 3.53 9.91 Lauric acid B 5.10 7.0189 0.2393 3.48 9.75
C 5.20 7.0379 0.2393 3.54 9.92
C002coco A 4.60 7.0848 0.2447 3.18 8.91 Lauric acid B 4.60 7.0612 0.2447 3.19 8.94
C 4.50 7.0340 0.2447 3.13 8.78
C022coco A 6.05 7.0384 0.2470 4.25 11.91 Lauric acid B 6.05 7.0271 0.2470 4.25 11.93
C 6.10 7.0450 0.2470 4.28 12.00
C032coco A 6.20 7.0188 0.2447 4.32 12.13 Lauric acid B 6.20 7.0114 0.2447 4.33 12.14
C 6.00 7.0920 0.2447 4.14 11.61
Where:
C001coco – brand 1, coconut oil bottle 1
C021coco – brand 1, coconut oil bottle 2
C031coco – brand 1, coconut oil bottle 3
C002coco – brand 2, coconut oil bottle 1
C022coco – brand 2, coconut oil bottle 2
C032coco – brand 2, coconut oil bottle 3
Appendix
167
Table A4. Free Fatty Acid and Acid Values of Waste Oil
Titer Volume
(ml)
Weight of Sample (g)
Normality of NaOH Solution
(N)
Free Fatty Acid (FFA)
% Acid Value
W001p A 1.85 7.0786 0.2393 1.60 3.51
Palmitic acid B 1.90 7.0312 0.2393 1.66 3.63
C 1.85 7.0473 0.2393 1.61 3.52
W021p A 6.70 7.0392 0.2393 5.83 12.78
Palmitic acid B 6.80 7.0512 0.2393 5.91 12.95
C 6.80 7.0207 0.2393 5.93 13.00
W031p A 14.70 7.0067 0.2393 12.85 28.16
Palmitic acid B 14.50 7.0263 0.2393 12.64 27.70
C 14.60 7.0282 0.2393 12.73 27.89
W002s A 12.70 7.0619 0.2393 11.02 24.14
Oleic acid B 12.60 7.0435 0.2393 10.96 24.02
C 12.60 7.0326 0.2393 10.98 24.05
W022s A 6.75 7.0492 0.2393 5.87 12.85
Oleic acid B 6.75 7.0635 0.2393 5.85 12.83
C 6.80 7.0481 0.2393 5.91 12.95
W032s A 13.70 7.0341 0.2393 11.93 26.15
Oleic acid B 13.85 7.0154 0.2393 12.09 26.50
C 13.20 7.0523 0.2393 11.47 25.13
W003s A 0.60 7.0133 0.2393 0.52 1.15
Oleic acid B 0.55 7.0529 0.2393 0.48 1.05
C 0.60 7.0288 0.2393 0.52 1.15
W023s A 1.10 7.0751 0.2393 0.95 2.09
Oleic acid B 1.05 7.0608 0.2393 0.91 2.00
C 1.05 7.0495 0.2393 0.91 2.00
W033s A 1.00 7.0378 0.2393 0.87 1.91
Oleic acid B 0.95 7.0314 0.2393 0.83 1.81
C 0.90 7.0472 0.2393 0.78 1.71
Where: W001p – waste oil from source 1, batch 1
W021p – waste oil from source 1, batch 2
W031p – waste oil from source 1, batch 3
W002s – waste oil from source 2, batch 1
W022s – waste oil from source 2, batch 2
W032s – waste oil from source 2, batch 3
W003s – waste oil from source 3, batch 1
W023s – waste oil from source 3, batch 2
W033s – waste oil from source 3, batch 3
Appendix
168
IODINE VALUE
Table A5. Iodine value of Soybean oil
Iodine value calculated ranged from 116.70 - 134.47 (Table 3.10)
Soybean oil
Rep
licat
es A
Titer Volume of Blank
(ml)
B Titer
Volume of Sample
(ml)
A-B (ml)
Weight of
Sample (g)
Normality of
Na2S2O3 Solution
(N)
Iodine Value
Average Iodine Value
C001soy A 49.70 28.90 20.80 0.2120 0.1042 129.7349 B 49.70 29.00 20.70 0.2063 0.1042 132.6785 C 49.70 28.90 20.80 0.2080 0.1042 132.2298
131.55
C021soy A 50.10 28.25 21.85 0.2182 0.1042 132.4116 B 50.10 30.00 20.10 0.2009 0.1042 132.2956 C 50.10 29.14 20.96 0.2135 0.1042 129.8144
131.51
C031soy A 52.05 31.30 20.75 0.2015 0.1029 134.4683 B 52.05 30.65 21.40 0.2091 0.1029 133.6401 C 52.05 30.70 21.35 0.2122 0.1029 131.3801
133.16
C002soy A 51.20 30.60 20.60 0.2094 0.1029 128.4599 B 51.20 30.10 21.10 0.2128 0.1029 129.4756 C 51.20 30.70 20.50 0.2070 0.1029 129.3185
129.08
C022soy A 51.20 30.50 20.70 0.2088 0.1029 129.4544 B 51.20 31.40 19.80 0.2048 0.1029 126.2444 C 51.20 31.80 19.40 0.2060 0.1029 122.9735
126.22
C032soy A 50.85 29.50 21.35 0.2389 0.1029 116.6967 B 50.85 29.20 21.65 0.2357 0.1029 119.9431 C 50.85 28.70 22.15 0.2410 0.1029 120.0145
118.88
Appendix
169
Table A6. Iodine value of Canola Oil
Iodine value calculated ranged from 111.02-132.92 (Table 3.10)
Canola oil
Rep
licat
es
A Titer
Volume of Blank (ml)
B Titer
Volume of
Sample (ml)
A-B (ml)
Weight of
Sample (g)
Normality of
Na2S2O3 Solution
(N)
Iodine Value
Average Iodine Value
C001can A 49.70 27.40 22.30 0.2428 0.1042 121.447
B 49.70 28.20 21.50 0.2342 0.1042 121.389
C 49.70 28.60 21.10 0.2303 0.1042 121.148 121.33
C021can A 50.10 29.30 20.80 0.2372 0.1042 115.952
B 50.10 29.20 20.90 0.2383 0.1042 115.972
C 50.10 28.95 21.15 0.2331 0.1042 119.977 117.30
C031can A 52.05 30.10 21.95 0.2309 0.1029 124.133
B 52.05 28.90 23.15 0.2457 0.1029 123.033
C 52.05 29.30 22.75 0.2445 0.1029 121.501 122.89
C002can A 51.20 30.10 21.10 0.2410 0.1029 114.325
B 51.20 29.95 21.25 0.2473 0.1029 112.205
C 51.20 30.20 21.00 0.2470 0.1029 111.020 112.52
C022can A 51.20 30.50 20.70 0.2305 0.1029 117.267
B 51.20 30.50 20.70 0.2339 0.1029 115.563
C 51.20 30.55 20.65 0.2427 0.1029 111.103 114.64
C032can A 50.85 29.80 21.05 0.2068 0.1029 132.917
B 50.85 29.80 21.05 0.2089 0.1029 131.580
C 50.85 29.50 21.35 0.2161 0.1029 129.009 131.17
Appendix
170
Table A7. Iodine value of Coconut oil
Iodine value calculated ranged from 6.08-9.26 (Table 3.10)
A Titer
Volume of Blank (ml)
B Titer
Volume of Sample
(ml)
A-B (ml)
Weight of
Sample (g)
Normality of
Na2S2O3 Solution
(N)
Iodine Value
Average Iodine Value
C001coco A 49.70 43.55 6.15 1.2209 0.1042 6.6608
B 49.70 43.00 6.70 1.2353 0.1042 7.1719
C 49.70 42.85 6.85 1.2188 0.1042 7.4317 7.09
C021coco A 50.10 42.90 7.20 1.2228 0.1042 7.7859
B 50.10 42.95 7.15 1.2134 0.1042 7.7917
C 50.10 43.25 6.85 1.2254 0.1042 7.3917 7.66
C031coco A 52.05 44.20 7.85 1.2174 0.1029 8.4200
B 52.05 44.30 7.75 1.2240 0.1029 8.2679
C 52.05 45.35 6.70 1.2154 0.1029 7.1951 7.96
C002coco A 51.20 43.10 8.10 1.2243 0.1029 8.6392
B 51.20 43.60 7.60 1.2397 0.1029 8.0052
C 51.20 43.90 7.30 1.2182 0.1029 7.8249 8.16
C022coco A 51.20 45.60 5.60 1.2033 0.1029 6.0770
B 51.20 43.50 7.70 1.2140 0.1029 8.2823
C 51.20 43.55 7.65 1.2152 0.1029 8.2204 7.53
C032coco A 50.85 42.60 8.25 1.2176 0.1029 8.8476
B 50.85 42.25 8.60 1.2128 0.1029 9.2595
C 50.85 42.40 8.45 1.2126 0.1029 9.0995 9.07
Appendix
171
Table A8. Iodine value of Waste oil
Iodine value calculated ranged from 46.69 – 68.95 (Table 3.11)
A Titer
Volume of Blank (ml)
B Titer
Volume of Sample
(ml)
A-B (ml)
Weight of
Sample (g)
Normality of
Na2S2O3 Solution
(N)
Iodine Value
Average Iodine Value
W001p A 51.10 33.50 17.60 0.4465 0.1029 51.4717
B 51.10 32.30 18.80 0.4836 0.1029 50.7631
C 51.10 32.20 18.90 0.4838 0.1029 51.0121 51.08
W021p A 51.10 32.55 18.55 0.4757 0.1018 50.3756 B 51.10 32.30 18.80 0.4850 0.1018 50.0755
C 51.10 33.30 17.80 0.4801 0.1018 47.8958 49.45
W031p A 51.10 33.80 17.30 0.4837 0.1018 46.2040
B 51.10 33.60 17.50 0.4709 0.1018 48.0086
C 51.10 33.50 17.60 0.4770 0.1018 47.6654 47.29
W002s A 51.10 41.15 9.95 0.2090 0.1029 62.1661 B 51.10 40.50 10.60 0.2174 0.1029 63.6683
C 51.10 40.70 10.40 0.2095 0.1029 64.8226 63.55
W022s A 51.10 40.95 10.15 0.2144 0.1018 61.1576
B 51.10 42.70 8.40 0.2097 0.1018 51.7476
C 51.10 41.90 9.20 0.2155 0.1018 55.1506 56.02
W032s A 51.10 41.55 9.55 0.2147 0.1018 57.4620 B 51.10 44.00 7.10 0.2118 0.1018 43.3054
C 51.10 44.70 6.40 0.2103 0.1018 39.3143 46.69
W003s A 51.10 40.50 10.60 0.2041 0.1029 67.8172
B 51.10 40.40 10.70 0.2025 0.1029 68.9979
C 51.10 39.50 11.60 0.2163 0.1029 70.0291 68.95
W023s A 51.10 44.30 6.80 0.2148 0.1018 40.8963 B 51.10 44.35 6.75 0.2031 0.1018 42.9342
C 51.10 41.70 9.40 0.2125 0.1018 57.1450 46.99
W033s A 51.10 41.70 9.40 0.2016 0.1018 60.2347
B 51.10 41.70 9.40 0.2011 0.1018 60.3845
C 51.10 41.20 9.90 0.2101 0.1018 60.8721 60.50
Appendix
172
PHOSPHOROUS CONTENT
Table A9. Phosphorous Content of Soybean oil
Phosphorus content of soybean oil ranged from 0.0003%-0.0277 % (table 3.12)
A Phosporous Content of Sample in
Aliquot (mg)
B Phosphorous
Content of Blank (mg)
A-B (mg)
W Weight of Sample
(g)
Phosphorus % 10(A-B)/WV
Average (%)
C001soy A 0.0830 0.0003 0.0833 3.0307 0.0275 B 0.0830 0.0003 0.0833 3.0287 0.0275
C 0.0830 0.0003 0.0833 3.0470 0.0274
0.03
C021soy A 0.0015 0.0003 0.0018 3.0315 0.0006 B 0.0010 0.0003 0.0013 3.0211 0.0004
C 0.0830 0.0003 0.0833 3.0060 0.0277
0.01
C031soy A 0.0005 0.0003 0.0008 3.0186 0.0003 B 0.0006 0.0003 0.0009 3.0246 0.0003
C 0.0830 0.0003 0.0833 3.0481 0.0273
0.01
C002soy A 0.0008 0.0003 0.0011 3.0258 0.0004 B 0.0042 0.0003 0.0045 3.0010 0.0015
C 0.0830 0.0003 0.0834 3.0124 0.0277
0.01
C022soy A 0.0830 0.0003 0.0834 3.0238 0.0276 B 0.0830 0.0003 0.0834 3.0377 0.0274
C 0.0830 0.0003 0.0834 3.0262 0.0275
0.03
C032soy A 0.0830 0.0003 0.0834 3.0510 0.0273 B 0.0830 0.0003 0.0834 3.0347 0.0275
C 0.0830 0.0003 0.0834 3.0383 0.0274
0.03
Appendix
173
Table A10. Phosphorous Content of Canola Oil
Phosphorus content of canola oil ranged from 0.0001%-0.0276% (table 3.12)
A Phosporous Content of Sample in
Aliquot (mg)
B Phosphorous
Content of Blank (mg)
A-B
W Weight of Sample
(g)
Phosphorus % 10(A-B)/WV
Average (%)
C002can A 0.0014 0.0003 0.0018 3.0570 0.0006 B 0.0015 0.0003 0.0018 3.0980 0.0006
C 0.0010 0.0003 0.0013 3.0718 0.0004
ND
C022can A 0.0001 0.0003 0.0004 3.0408 0.0001 B 0.0014 0.0003 0.0017 3.0971 0.0005
C 0.0013 0.0003 0.0016 3.0479 0.0005
ND
C032can A -0.0002 0.0003 0.0002 3.0211 0.0001 B 0.0001 0.0003 0.0004 3.0210 0.0001
C 0.0001 0.0003 0.0004 3.0150 0.0001
ND
C001can A 0.0830 0.0001 0.0832 3.0156 0.0276 B 0.0830 0.0001 0.0832 3.0303 0.0274 C 0.0830 0.0001 0.0832 3.0180 0.0276
0.03
C021can A 0.0830 0.0001 0.0832 3.0200 0.0275 B 0.0830 0.0001 0.0832 3.0110 0.0276
C 0.0830 0.0001 0.0832 3.0320 0.0274
0.03
C031can A 0.0830 0.0001 0.0832 3.0185 0.0275 B 0.0830 0.0001 0.0832 3.0348 0.0274
C 0.0830 0.0001 0.0832 3.0182 0.0276
0.03
ND – not detectable, percentage of phosphorous is below significant range.
Appendix
174
MOISTURE AND VOLATILE MATTER
Table A11. Moisture Content and Volatile Matter of Soybean oil
Soybean Oil
Initial
weight (A)
Final weight
(B)
Weight loss (C) A-B
(D) Weight of sample (g)
Moisture and Volatile Matter
Content (C/100)/D
A 52.1399 52.1363 0.0036 20.16 0.0179
B 51.7189 51.7081 0.0108 20.16 0.0536
C00
1soy
C 53.2781 53.2676 0.0105 20.0172 0.0525 A 52.5399 52.527 0.0129 20.0091 0.0645
B 51.0513 51.0399 0.0114 20.0266 0.0569
C02
1soy
C 52.8001 52.7895 0.0106 20.0158 0.0530 A 53.2363 53.2251 0.0112 20.0407 0.0559
B 52.8782 52.8664 0.0118 20.1392 0.0586
C03
1soy
C 52.4063 52.3965 0.0098 19.6533 0.0499
A 38.7112 38.6991 0.0121 19.9945 0.0605
B 38.4621 38.4501 0.012 20.1751 0.0595
C00
2soy
C 39.6221 39.6101 0.012 19.9839 0.0600
A 38.6321 38.6205 0.0116 20.001 0.0580 B 39.7397 39.7272 0.0125 20.005 0.0625
C02
2soy
C 41.6468 41.6354 0.0114 19.8313 0.0575
A 39.3884 39.3713 0.0171 19.8296 0.0862 B 39.6743 39.6622 0.0121 20.0177 0.0604
C03
2soy
C 38.7287 38.7152 0.0135 20.0713 0.0673
Appendix
175
Table A12. Moisture Content and Volatile Matter of Canola oil
Canola Oil
Initial
weight (A)
Final weight
(B)
Weight loss (C) A-B
(D) Weight of sample (g)
Moisture and Volatile Matter
Content (C/100)/D
A 51.7033 51.693 0.0103 20.0109 0.0515 B 52.1775 52.1669 0.0106 19.9974 0.0530
C00
1can
C 52.7434 52.7329 0.0105 20.0059 0.0525
A 52.0226 52.0102 0.0124 20.009 0.0620
B 53.06651 53.0561 0.01041 20.0457 0.0519
C02
1can
C 51.8279 51.8181 0.0098 20.0305 0.0489
A 52.5649 52.5556 0.0093 20.0399 0.0464
B 52.7089 52.6974 0.0115 20.5099 0.0561
C03
1can
C 52.4755 52.4587 0.0168 20.0712 0.0837
A 46.5871 46.5767 0.0104 20.0624 0.0518
B 51.1944 51.18 0.0144 20.0068 0.0720
C00
2can
C 52.5624 52.5528 0.0096 20.0574 0.0479
A 51.3157 51.3061 0.0096 20.0048 0.0480 B 52.1811 52.1704 0.0107 20.0178 0.0535
C02
2can
C 53.0312 53.0204 0.0108 20.0233 0.0539
A 56.3132 56.3025 0.0107 20.0061 0.0535
B 52.1091 52.0981 0.011 20.0166 0.0550
C03
2can
C 46.9241 46.9139 0.0102 20.043 0.0509
Appendix
176
Table A13. Moisture Content and Volatile Matter of Coconut oil
Coconut Oil
Initial
weight (A)
Final weight
(B)
Weight loss (C) A-B
(D) Weight of sample (g)
Moisture and Volatile Matter
Content (C/100)/D
A 38.3768 38.3226 0.0542 19.8037 0.2737
B 37.3445 37.3201 0.0244 19.9517 0.1223 C00
1coc
o
C 39.8921 39.8351 0.057 20.158 0.2828 A 38.3345 38.2758 0.0587 19.995 0.2936
B 38.623 38.5666 0.0564 20.0017 0.2820 C02
1coc
o
C 38.7602 38.7058 0.0544 20.0871 0.2708
A 38.1878 38.1221 0.0657 20.0809 0.3272
B 38.7479 38.6869 0.061 20.0571 0.3041 C03
1coc
o
C 39.5678 39.515 0.0528 20.0202 0.2637
A 21.4876 21.4682 0.0194 9.9937 0.1941
B 20.3899 20.3605 0.0294 10.0235 0.2933 C00
2coc
o
C 21.9874 21.9589 0.0285 10.0641 0.2832
A 50.2021 50.1209 0.0812 20.5037 0.3960
B 51.0862 51.0066 0.0796 20.0162 0.3977 C02
2coc
o
C 68.4494 68.3661 0.0833 19.8821 0.4190 A 21.6142 21.5874 0.0268 9.9653 0.2689
B 28.7247 28.6998 0.0249 10.073 0.2472 C03
2coc
o
C 31.6382 31.6164 0.0218 10.0149 0.2177
Appendix
177
Table A14. Moisture Content and Volatile Matter of Waste oil
Waste Oil
Initial
weight (A)
Final weight
(B)
Weight loss (C) A-B
(D) Weight of sample (g)
Moisture and Volatile Matter
Content (C/100)/D
A 38.003 37.9818 0.0212 19.255 0.1101 B 38.0366 38.0195 0.0171 19.3569 0.0883
W00
1p
C 37.9992 37.9708 0.0284 19.295 0.1472
A 38.6443 38.6167 0.0276 19.7718 0.1396
B 38.2741 38.1999 0.0742 19.6048 0.3785
W02
1p
C 39.3456 39.3195 0.0261 19.7571 0.1321
A 70.9569 70.9407 0.0162 20.048 0.0808
B 46.3302 46.2962 0.034 20.0409 0.1697
W03
1p
C 52.235 52.2031 0.0319 19.9561 0.1599
A 37.9908 37.9505 0.0403 20.0256 0.2012
B 38.084 38.0429 0.0411 19.9961 0.2055
W00
2s
C 38.0547 38.0102 0.0445 19.9674 0.2229
A 39.0682 39.0395 0.0287 19.4728 0.1474 B 38.5366 38.5043 0.0323 19.7786 0.1633
W02
2s
C 38.4749 38.4469 0.028 19.7795 0.1416
A 51.5518 51.5059 0.0459 19.9691 0.2299
B 38.0771 38.0422 0.0349 20.0867 0.1737
W03
2s
C 51.915 51.8657 0.0493 19.9403 0.2472
A 38.0671 38.0546 0.0125 19.9725 0.0626
B 37.9598 37.9443 0.0155 19.9366 0.0777
W00
3s
C 37.9953 37.9817 0.0136 19.7988 0.0687
A 38.6315 38.6287 0.0028 19.9357 0.0140
B 39.5839 39.5708 0.0131 19.7973 0.0662
W02
3s
C 38.839 38.8264 0.0126 20.111 0.0627
A 72.0262 71.8519 0.1743 20.0709 0.8684 B 50.0249 49.876 0.1489 19.9803 0.7452
W03
3s
C 52.9749 52.8251 0.1498 20.0925 0.7456
Appendix
178
BIODIESEL SYNTHESIS
Acid pretreatment, one-step basic transesterification (Method 1) – coconut oil methyl esters
– waste oil methyl ester
Table A.15 Pretreatment of Coconut oil - METHANOLYSIS
C001coco C021coco C031coco C002coco C022coco C032co co Coconut Oil Properties . Mass of feedstock (g) 200.39 200.06 200.04 200.39 200.35 200.56 Free Fatty Acids (%) 3.5843 3.5214 3.5155 3.1656 4.2589 4.2637 Mass of FFA in stock (g) 7.1826 7.0449 7.0324 6.3435 8.5327 8.5513 Mr. of Free fatty Acid (g/moles) 200.3 200.3 200.3 200.3 200.3 200.3
Moles of Free fatty Acid (moles) 0.0359 0.0352 0.0351 0.0317 0.0426 0.0427 Methanol Properties Moles of Methanol (moles) 0.7172 0.7034 0.7022 0.6334 0.8520 0.8538 Mr. of Methanol (g/moles) 32 32 32 32 32 32 Mass of Methanol (g) 22.9498 22.5100 22.4700 20.2689 27.2638 27.3231 Density of Methanol (g/ml) 0.791 0.791 0.791 0.791 0.791 0.791
Volume of Methanol (ml) 29.0137 28.4576 28.4071 25.6245 34.4675 34.5425 Acid Properties
Mass of H2SO4 ( 10% of FFA) g 0.7183 0.7045 0.7032 0.6344 0.8533 0.8551 Density of H2SO4 (g/ml) 1.8 1.8 1.8 1.8 1.8 1.8
Volume of H2SO4 (ml) 0.3990 0.3914 0.3907 0.3524 0.4740 0.4751 Condition set for coconut oil methanol pretreatment: 20:1methanol to FFA, 10% sulphuric acid.
Table A.16 FFA of Pretreated Coconut Oil.
Titer Volume
(ml)
Weight of Sample (g)
Normality of NaOH Solution
(N)
Free Fatty Acid (FFA)
%
Acid Value (mg
KOH/g)
C001coco-1-Oil 6.60 28.2597 0.1095 0.5115 1.4347 C021coco-1-Oil 6.80 28.2553 0.1095 0.5271 1.4784 C031coco-1-Oil 10.05 28.3894 0.1095 0.7753 2.1746 C002coco-1-Oil 11.60 28.2218 0.1095 0.9002 2.5249 C022coco-1-Oil 6.85 28.2666 0.1095 0.5307 1.4887
C032coco-1-Oil 6.35 28.2848 0.1095 0.4917 1.3791 Acid Value = (ml)(N)(56.1*)/(g)
* 56.1 = molecular weight (or equivalent weight) of KOH.
Appendix
179
Table A.17 Transesterification of Pretreated Coconut Oil
Catalyst to neutralise leftover FFA before transesterification
C001coco-
1-oil C021coco-
1-oil C031coco-
1-oil C002coco-
1-oil C022coco-
1-oil C032coco-
1-oil Mass of pretreated oil (g) 100.7400 100.2700 100.9600 100.5800 100.4900 100.3900 Acid Value (mg KOH/g) 1.4347 1.4784 2.5249 2.5249 1.4887 1.3791 Mass of KOH catalyst (neutralising) g 0.1445 0.1482 0.2549 0.2540 0.1496 0.1384 Mass of NaOH catalyst (neutralising) g 0.0852 0.0874 0.1503 0.1498 0.0882 0.0816 Mass of NaOH catalyst (1% of Oil) g 1.0074 1.0027 1.0096 1.0058 1.0049 1.0039
Total mass of catalyst (g) 1.0926 1.0901 1.1599 1.1556 1.0931 1.0855
C001coco-
1-oil C021coco-
1-oil C031coco-
1-oil C002coco-
1-oil C022coco-
1-oil C032coco-
1-oil Oil Properties Mass of feedstock (g) 100.7400 100.2700 100.9600 100.5800 100.4900 100.3900 Mr. of triglyceride (Lauric) (g/moles) 639.0000 639.0000 639.0000 639.0000 639.0000 639.0000 Moles of triglyceride (moles) 0.1577 0.1569 0.1580 0.1574 0.1573 0.1571 Methanol Properties Moles of Methanol (moles) 0.9459 0.9415 0.9480 0.9444 0.9436 0.9426 Mr. of Methanol (g/moles) 32.0000 32.0000 32.0000 32.0000 32.0000 32.0000 Mass of Methanol (g) 30.2693 30.1281 30.3354 30.2212 30.1942 30.1641 Density of Methanol (g/ml) 0.7910 0.7910 0.7910 0.7910 0.7910 0.7910
Volume of Methanol (ml) 38.2671 38.0886 38.3507 38.2063 38.1722 38.1342
Table A.18 Pretreatment of Waste oil – METHANOLYSIS
20:1methanol to FFA, 10% sulphuric acid.
W001p W021p W031p W002s W022s W032s W023s
Oil Properties . . . . . Mass of feedstock (g) 200.64 200.53 200.1 200.14 200.3 200.26 200.69 Free Fatty Acids (%) 1.6215 5.8907 12.7402 12.0995 6.4738 13.0323 1.0193 Mass of FFA in stock (g) 3.2534 11.8126 25.4931 24.2159 12.9670 26.0985 2.0456 Mr. of Free fatty Acid (g/moles) 256.42 256.42 256.42 282.46 282.46 282.46 282.46 Moles of Free fatty Acid (moles) 0.0127 0.0461 0.0994 0.0857 0.0459 0.0924 0.0072
Methanol Properties Moles of Methanol (moles) 0.2538 0.9213 1.9884 1.7146 0.9181 1.8479 0.1448 Mr. of Methanol (g/moles) 32 32 32 32 32 32 32 Mass of Methanol (g) 8.1201 29.4832 63.6285 54.8687 29.3808 59.1341 4.6350 Density of Methanol (g/ml) 0.791 0.791 0.791 0.791 0.791 0.791 0.791 Volume of Methanol (ml) 10.2656 37.2733 80.4405 69.3662 37.1438 74.7587 5.8597
Acid Properties Mass of H2SO4 ( 10% of FFA) g 0.3253 1.1813 2.5493 2.4216 1.2967 2.6098 0.2046 Density of H2SO4 (g/ml) 1.8 1.8 1.8 1.8 1.8 1.8 1.8
Appendix
180
Volume of H2SO4 (ml) 0.1807 0.6563 1.4163 1.3453 0.7204 1.4499 0.1136
Molecular weight of palitic acid 256.42 Molecular weight of oliec acid 282.46
Table A.19 Transesterification of Pretreated Oil
Catalyst to neutralise leftover FFA before transesterification Catalyst W001p W021p W031p W002s W022s W032s W023s
Mass of pretreated oil (g) 100.5200 100.6100 100.7500 100.1600 100.8800 100.4400 100.8900 Acid Value (mg KOH/g) 0.9953 0.0000 0.0000 0.0000 0.0000 0.0000 1.8398 Mass of KOH catalyst (neutralising) g 0.1001 0.0000 0.0000 0.0000 0.0000 0.0000 0.1856 Mass of NaOH catalyst (neutralising) g
0.0590 0.0000 0.0000 0.0000 0.0000 0.0000 0.1095
Mass of NaOH catalyst (1% of Oil) g 1.0052 1.0061 1.0075 1.0016 1.0088 1.0044 1.0089 Total mass of catalyst (g) 1.0642 1.0061 1.0075 1.0016 1.0088 1.0044 1.1184
Oil Properties Mass of feedstock (g) 100.5200 100.6100 100.7500 100.1600 100.8800 100.4400 100.8900 Mr. of triglyceride (palmitic) (g/moles) 806.7360 806.7360 806.7360 885.4300 885.4300 885.4300 885.4300 Moles of triglyceride (moles) 0.1246 0.1247 0.1249 0.1131 0.1139 0.1134 0.1139 Methanol Properties Moles of Methanol (moles) 0.7476 0.7483 0.7493 0.6787 0.6836 0.6806 0.6837 Mr. of Methanol (g/moles) 32.0000 32.0000 32.0000 32.0000 32.0000 32.0000 32.0000 Mass of Methanol (g) 23.9234 23.9448 23.9781 21.7191 21.8752 21.7798 21.8774 Density of Methanol (g/ml) 0.7910 0.7910 0.7910 0.7910 0.7910 0.7910 0.7910 Volume of Methanol (ml) 30.2445 30.2715 30.3137 27.4577 27.6551 27.5345 27.6579
Molecular weight of tripalmitoyl glycerol 806.736 Molecular weight of trioleoyl glycerol 885.43
Appendix
181
One Step Base Transesterification (Method 2A) and T wo Step Base Transesterification
(Method 2B)
– Coconut oil Methyl and ethyl esters
– Soybean oil methyl and ethyl esters
– Canola oil methyl and ethyl esters
Table A.20 Coconut oil - METHANOLYSIS
Oil Properties C001coco C021coco C031coco C002coco C022coco C032coco Mass of feedstock (g) 100.0600 100.4500 100.2100 100.1300 100.1500 100.1900 Mr. of triglyceride (Lauric) (g/moles) 639.0000 639.0000 639.0000 639.0000 639.0000 639.0000 Moles of triglyceride (moles) 0.1566 0.1572 0.1568 0.1567 0.1567 0.1568 Methanol Properties Moles of Methanol (moles) 0.9395 0.9432 0.9409 0.9402 0.9404 0.9408 Mr. of Methanol (g/moles) 32.0000 32.0000 32.0000 32.0000 32.0000 32.0000 Mass of Methanol (g) 30.0650 30.1822 30.1100 30.0860 30.0920 30.1040 Density of Methanol (g/ml) 0.7910 0.7910 0.7910 0.7910 0.7910 0.7910 Volume of Methanol (ml) 38.0088 38.1570 38.0658 38.0354 38.0430 38.0582 Catalyst Mass of NaOH catalyst (1% of Oil) g 1.0006 1.0045 1.0021 1.0013 1.0015 1.0019 Molecular weight of trilauryl glycerol 639.00
Table A.21 Coconut oil – ETHANOLYSIS
Oil Properties C001coco C021coco C031coco C002coco C022coco C032coco Mass of feedstock (g) 100.2600 100.2400 100.1800 100.0200 100.4200 100.1000 Mr. of triglyceride (lauric) (g/moles) 639.0000 639.0000 639.0000 639.0000 639.0000 639.0000 Moles of triglyceride (moles) 0.1569 0.1569 0.1568 0.1565 0.1572 0.1567 Methanol Properties Moles of Methanol (moles) 0.9414 0.9412 0.9407 0.9392 0.9429 0.9399 Mr. of Methanol (g/moles) 46.0000 46.0000 46.0000 46.0000 46.0000 46.0000 Mass of Methanol (g) 43.3048 43.2962 43.2702 43.2011 43.3739 43.2357 Density of Methanol (g/ml) 0.7890 0.7890 0.7890 0.7890 0.7890 0.7890 Volume of Methanol (ml) 54.8857 54.8747 54.8419 54.7543 54.9733 54.7981 Catalyst Mass of KOH catalyst (0.5% of Oil) g 0.5013 0.5012 0.5009 0.5001 0.5021 0.5005
Molecular weight of trilauryl glycerol 639.00
Appendix
182
Table A.22 Soybean oil - METHANOLYSIS
Oil Properties C001soy C021soy C031soy C002soy C022soy C032soy Mass of feedstock (g) 200.0000 200.5700 200.9600 200.0300 200.7100 200.2400 Mr. of triglyceride (oleic) (g/moles) 885.43 885.43 885.43 885.43 885.43 885.43 Moles of triglyceride (moles) 0.2259 0.2265 0.2270 0.2259 0.2267 0.2262 Methanol Properties Moles of Methanol (moles) 1.3553 1.3591 1.3618 1.3555 1.3601 1.3569 Mr. of Methanol (g/moles) 32.0000 32.0000 32.0000 32.0000 32.0000 32.0000 Mass of Methanol (g) 43.3688 43.4924 43.5769 43.3753 43.5227 43.4208 Density of Methanol (g/ml) 0.7910 0.7910 0.7910 0.7910 0.7910 0.7910 Volume of Methanol (ml) 54.8278 54.9840 55.0909 54.8360 55.0224 54.8936 Catalyst Mass of NaOH catalyst (1% of Oil) g 2.0000 2.0057 2.0096 2.0003 2.0071 2.0024
Table A.23 Soybean oil – ETHANOLYSIS
Oil Properties C001soy C021soy C031soy C002soy C022soy C032soy Mass of feedstock (g) 100.5000 100.4300 100.2300 100.7900 101.0700 100.0300 Mr. of triglyceride (oleic) (g/moles) 885.43 885.43 885.43 885.43 885.43 885.43 Moles of triglyceride (moles) 0.1135 0.1134 0.1132 0.1138 0.1141 0.1130 Methanol Properties Moles of Methanol (moles) 0.6810 0.6806 0.6792 0.6830 0.6849 0.6778 Mr. of Methanol (g/moles) 46.0000 46.0000 46.0000 46.0000 46.0000 46.0000 Mass of Methanol (g) 31.3272 31.3053 31.2430 31.4175 31.5048 31.1806 Density of Methanol (g/ml) 0.7890 0.7890 0.7890 0.7890 0.7890 0.7890 Volume of Methanol (ml) 39.7049 39.6772 39.5982 39.8195 39.9301 39.5192 Catalyst Mass of KOH catalyst (0.5% of Oil) g 0.5025 0.5022 0.5012 0.5040 0.5054 0.5002
Table A.24 Canola oil – METHANOLYSIS
Oil Properties C001can C021can C031can C002can C022can C032can Mass of feedstock (g) 200.7400 205.0800 200.5800 202.5400 200.9400 202.9700 Mr. of triglyceride (oleic) (g/moles) 885.43 885.43 885.43 885.43 885.43 885.43 Moles of triglyceride (moles) 0.2267 0.2316 0.2265 0.2287 0.2269 0.2292 Methanol Properties Moles of Methanol (moles) 1.3603 1.3897 1.3592 1.3725 1.3616 1.3754 Mr. of Methanol (g/moles) 32.0000 32.0000 32.0000 32.0000 32.0000 32.0000 Mass of Methanol (g) 43.5292 44.4703 43.4945 43.9195 43.5726 44.0128 Density of Methanol (g/ml) 0.7910 0.7910 0.7910 0.7910 0.7910 0.7910 Volume of Methanol (ml) 55.0306 56.2204 54.9868 55.5241 55.0855 55.6420 Catalyst Mass of NaOH catalyst (1% of Oil) g 2.0074 2.0508 2.0058 2.0254 2.0094 2.0297
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183
Table A.25 Canola oil – ETHANOLYSIS
Oil Properties C001can C021can C031can C002can C022can C032can Mass of feedstock (g) 101.2700 100.2400 101.0200 100.7400 101.1100 100.6300 Mr. of triglyceride (oleic) (g/moles) 885.43 885.43 885.43 885.43 885.43 885.43 Moles of triglyceride (moles) 0.1144 0.1132 0.1141 0.1138 0.1142 0.1137 Methanol Properties Moles of Methanol (moles) 0.6862 0.6793 0.6845 0.6827 0.6852 0.6819 Mr. of Methanol (g/moles) 46.0000 46.0000 46.0000 46.0000 46.0000 46.0000 Mass of Methanol (g) 31.5672 31.2461 31.4892 31.4020 31.5173 31.3677 Density of Methanol (g/ml) 0.7890 0.7890 0.7890 0.7890 0.7890 0.7890 Volume of Methanol (ml) 40.0091 39.6022 39.9103 39.7997 39.9459 39.7562 Catalyst Mass of KOH catalyst (0.5% of Oil) g 0.5064 0.5012 0.5051 0.5037 0.5056 0.5032
Base Neutralisation One Step Base Transesterification (Method 3)
– Coconut oil ethyl esters
– Waste oil ethyl esters
–
Table A.26 Transesterification of Waste Oil - ETHANOLYSIS
Catalyst KOH W001p W021p W031p W002s W022s W032s W003s W023s W033s
Mass of waste oil (g) 100.3300 100.3800 100.2900 100.3100 100.9900 100.4900 100.1900 100.7000 100.7000 Acid Value (mg KOH/g) 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Mass of KOH catalyst (neutralising) g 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Mass of KOH catalyst (1% of Oil) g 1.0033 1.0038 1.0029 1.0031 1.0099 1.0049 1.0019 1.0070 1.0070 Total mass of catalyst (g) 1.0033 1.0038 1.0029 1.0031 1.0099 1.0049 1.0019 1.0070 1.0070
Oil Properties Mass of feedstock - waste oil (g) 100.3300 100.3800 100.2900 100.3100 100.9900 100.4900 100.1900 100.7000 100.7000 Mr. of triglyceride (palmitic) (g/moles) 806.7360 806.7360 806.7360 885.4300 885.4300 885.4300 885.4300 885.4300 885.4300 Moles of triglyceride (moles) 0.1244 0.1244 0.1243 0.1133 0.1141 0.1135 0.1132 0.1137 0.1137 Methanol Properties Moles of Ethanol (moles) 0.7462 0.7466 0.7459 0.6797 0.6843 0.6810 0.6789 0.6824 0.6824 Mr. of Ethanol (g/moles) 46.0000 46.0000 46.0000 46.0000 46.0000 46.0000 46.0000 46.0000 46.0000 Mass of Ethanol (g) 34.3248 34.3419 34.3112 31.2679 31.4799 31.3240 31.2305 31.3895 31.3895 Density of Ethanol (g/ml) 0.7890 0.7890 0.7890 0.7890 0.7890 0.7890 0.7890 0.7890 0.7890
Volume of Ethanol (ml) 43.5042 43.5259 43.4869 39.6298 39.8985 39.7009 39.5824 39.7839 39.7839 Tripalmitoyl glycerol 806.736
trioleoyl glycerol 885.43
Appendix
184
Table A.27 Transesterification of Coconut Oil - ETHANOLYSIS
Catalyst KOH C001coco C021coco C031coco C002coco C022coco C032coco
Mass of coconut oil (g) 100.3400 100.1800 100.5800 100.2300 100.5900 100.2600 Acid Value (mg KOH/g) 10.05369 9.877451 9.861161 8.87956 11.94628 11.95847 Mass of KOH catalyst (neutralising) g 1.0088 0.9895 0.9918 0.8900 1.2017 1.1990 Mass of KOH catalyst (1% of Oil) g 1.0034 1.0018 1.0058 1.0023 1.0059 1.0026
Total mass of catalyst (g) 2.0122 1.9913 1.9976 1.8923 2.2076 2.2016
Oil Properties Mass of feedstock - waste oil (g) 100.3400 100.1800 100.5800 100.2300 100.5900 100.2600 Mr. of triglyceride (oleic) (g/moles) 639.0000 639.0000 639.0000 639.0000 639.0000 639.0000
Moles of triglyceride (moles) 0.1570 0.1568 0.1574 0.1569 0.1574 0.1569
Methanol Properties
Moles of Ethanol (moles) 0.9422 0.9407 0.9444 0.9411 0.9445 0.9414 Mr. of Ethanol (g/moles) 46.0000 46.0000 46.0000 46.0000 46.0000 46.0000 Mass of Ethanol (g) 43.3393 43.2702 43.4430 43.2918 43.4473 43.3048 Density of Ethanol (g/ml) 0.7890 0.7890 0.7890 0.7890 0.7890 0.7890
Volume of Ethanol (ml) 54.9295 54.8419 55.0608 54.8692 55.0663 54.8857 trilauryl glycerol (C39H74O6)
Appendix
185
ANALYSIS OF BIODIESEL
Table A28 Peak Areas of Coconut Oil Methyl Ester from Its Respective Fatty Acids. (GC-FID Analysis)
Samples C8 C10 C12 C14 C16 IS C18:0 C18:1 C18:2
Peak Areas (mvs-1) 1 C001coco-2A-WBDM 10215.54 8059.59 59282.94 20161.48 9008.21 23700.01 2736.90 5673.82 1213.12 2 C001coco-2B-WBDM 10114.54 8028.96 60056.33 20857.75 9485.01 25632.54 2944.62 6037.05 1281.11 3 C001coco-1-WBDM 7265.51 7047.01 56975.60 20670.90 9707.00 24333.47 3060.19 6369.89 1296.70
4 C021coco-2A-WBDM 9897.43 7659.50 53610.55 17205.11 7648.62 21369.39 2331.06 4920.37 941.41 5 C021coco-2B-WBDM 10001.15 7966.37 60628.70 20521.86 7762.22 21704.26 2612.82 5485.09 1065.61 6 C021coco-1-WBDM 8507.26 8459.70 67078.09 15442.25 7260.49 18882.84 2236.44 4839.08 2954.14
7 C031coco-2A-WBDM 9317.21 7063.61 50976.50 17090.40 7926.20 20442.19 2438.58 5760.38 1204.26 8 C031coco-2B-WBDM 10829.11 9847.58 73178.46 23642.27 10128.08 24549.16 2839.04 6763.62 1424.61 9 C031coco-1-WBDM 7809.92 7126.74 54717.43 19475.34 9162.03 23333.15 2853.60 6120.80 1190.06
10 C002coco-2A-WBDM 10131.50 7941.32 53551.11 16857.89 7361.37 19030.15 2172.71 4882.28 1183.99 11 C002coco-2B-WBDM 9568.89 7388.01 53500.94 17520.96 7717.11 25505.77 2337.26 5160.14 1250.21 12 C002coco-1-WBDM 9000.55 8132.87 61803.37 21247.43 9939.57 24211.82 3026.01 6724.84 1383.63
13 C022coco-2A-WBDM 8312.85 6360.19 46441.51 15931.09 7414.05 20017.31 2198.41 5072.04 1133.16 14 C022coco-2B-WBDM 10863.12 8820.08 63867.73 20559.06 8947.06 25422.31 2606.11 5885.24 1370.30 15 C022coco-1-WBDM 8200.26 7839.19 62901.34 22294.11 10837.10 25510.67 3468.16 7026.05 1248.65
16 C032coco-2A-WBDM 9698.10 7865.13 58772.27 19377.50 8754.04 19502.04 2499.07 6306.26 1353.61 17 C032coco-2B-WBDM 8652.75 7257.95 55278.53 19343.31 9350.65 23253.34 2769.60 6945.83 1477.34 18 C032coco-1-WBDM 7025.58 5916.02 44150.10 16850.99 8513.24 18832.94 2769.43 5591.67 977.62
Appendix
186
Table A29 Peak Areas of Coconut Oil Ethyl Ester From Its Respective Fatty Acids. (GC-FID).
Samples C8 C10 C12 C14 C16 IS C18:0 C18:1 C18:2 Peak Areas (mvs -1 )
1 C001coco-2A-WBDE 675.32 423.64 61.70 3278.54 954.69 567.45 26334.57 223.45 678.32 254.63 2 C001coco-2A-WBDE-salt 774.46 606.42 74.30 4317.96 1498.28 694.57 26114.95 236.10 779.69 307.42 3 C001coco-2B-WBDE 143.17 48.00 114.03 271.32 102.42 50.10 28388.09 30.88 55.14 14.57 4 C001coco-2B-WBDE-salt 112.97 48.08 107.65 301.65 114.52 54.69 26531.65 23.33 59.11 13.72 5 C001coco-3-WBDE 6674.18 5905.16 48413.27 17504.08 7221.63 26951.85 2990.29 13394.36 2498.33 6 C001coco-3-WBDE-salt 8146.84 7733.45 53945.37 19126.54 6758.85 23148.51 2761.64 5710.93 1171.28
7 C021coco-2A-WBDE 186.14 93.70 88.79 922.27 255.20 112.12 26576.78 21.58 68.95 52.78 8 C021coco-2A-WBDE-salt 303.02 214.85 141.55 849.07 303.95 251.48 27485.39 45.60 97.55 17.37 9 C021coco-2B-WBDE 208.95 76.80 109.77 399.16 141.52 62.09 23837.00 7.06 43.05 9.59 10 C021coco-2B-WBDE-salt 180.67 92.01 83.84 463.25 178.14 79.48 27671.40 19.72 83.98 7.02 11 C021coco-3-WBDE 6986.68 6877.41 44202.20 15585.03 6506.77 27577.20 2155.08 8447.94 1078.86 12 C021coco-3-WBDE-salt 5992.85 5097.28 36337.56 12878.63 5653.19 25641.07 1701.55 3707.90 866.73
13 C031coco-2A-WBDE 324.03 159.73 71.77 643.07 200.12 78.93 26626.44 79.59 525.66 56.78 14 C031coco-2A-WBDE-salt 493.75 302.36 19.22 1242.74 214.52 70.07 25520.69 25.88 80.98 36.63 14 C031coco-2B-WBDE 83.32 38.22 93.03 293.50 99.27 42.51 23356.90 19.48 37.70 10.70 15 C031coco-2B-WBDE-salt 61.89 37.49 107.38 255.53 89.02 43.02 26854.45 19.73 43.16 22.47 16 C031coco-3-WBDE 5699.87 36962.02 92.28 38448.41 14115.13 5770.47 22656.30 1369.41 2870.31 719.50 17 C031coco-3-WBDE-salt 5826.36 4987.62 38541.52 13136.01 6145.60 26844.71 2003.97 4108.77 880.34
18 C002coco-2A-WBDE 282.23 210.66 83.59 1405.22 489.72 233.47 21345.78 67.68 152.70 30.12 19 C002coco-2A-WBDE-salt 352.53 273.22 59.63 1637.29 522.66 214.42 22359.10 72.33 154.98 18.21 20 C002coco-2B-WBDE 133.24 36.36 79.85 294.75 104.13 47.32 27339.47 10.26 51.18 8.11 21 C002coco-2B-WBDE-salt 164.69 81.22 92.63 439.09 153.06 69.18 27534.24 25.39 43.47 8.79 22 C002coco-3-WBDE 4404.28 3755.62 32121.40 11966.95 5709.11 20619.96 1779.38 3833.96 757.24
Appendix
187
Continued….
23 C002coco-3-WBDE-salt 3444.03 3221.65 30278.34 11506.59 5557.40 25782.18 1849.07 3844.37 658.46
24 C022coco-2A-WBDE 562.12 449.97 62.24 3325.86 1149.38 530.25 23921.11 131.71 256.71 58.19 25 C022coco-2A-WBDE-salt 681.38 519.44 78.73 3485.20 1209.19 553.72 25002.42 155.59 385.11 76.74 26 C022coco-2B-WBDE 162.93 108.38 75.47 660.01 237.13 115.63 27320.91 26.12 103.59 13.34 27 C022coco-2B-WBDE-salt 390.65 170.05 106.57 602.78 214.90 107.49 23436.94 34.36 89.24 20.89 28 C022coco-3-WBDE 4844.15 4922.24 32556.23 12376.17 6024.35 29625.69 4784.14 3863.02 3024.44 29 C022coco-3-WBDE-salt 3920.95 3408.68 27705.71 10527.98 5127.04 17585.89 1521.23 3144.66 645.52
30 C032coco-2A-WBDE 1426.06 1239.84 28.14 8313.67 2740.36 1240.52 26282.06 337.66 712.65 185.36 31 C032coco-2A-WBDE-salt 930.69 722.45 26.24 5083.73 1804.16 871.29 17655.30 251.93 628.67 121.85 32 C032coco-2B-WBDE 783.74 583.52 37.78 3642.12 1182.47 579.77 21151.61 166.94 395.68 52.80 33 C032coco-2B-WBDE-salt 787.12 600.77 46.05 3442.73 1230.16 570.59 21984.72 159.11 360.65 59.17 34 C032coco-3-WBDE 3861.97 3607.02 26925.61 9932.80 4703.76 20043.07 1479.26 2941.03 577.29 35 C032coco-3-WBDE-salt 4128.85 3419.59 26481.73 9962.63 4703.60 17324.70 1468.45 2973.21 588.33
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188
Table A30 Peak Areas of Waste Oil Methyl Ester From Its Respective Fatty Acids. (GC Analysis).
Samples 7.74 8.18 8.84 9.14 9.82 10.08 IS 10.75 11.56
Peak Areas (mvs-1 ) 1 W001p-1-WBDM 14.94 43.80 1963.95 194.28 0.00 1750.23 322.05 2 W021p-1-WBDM 63.42 2569.02 264.56 0.00 2398.90 489.02 3 W031p-1-WBDM 11.77 53.01 2370.95 98.39 291.14 2206.69 385.50 4 W002s-1-WBDM 29.98 1350.92 71.05 287.28 344.16 1794.57 307.39 307.00 5 W022s-1-WBDM 37.79 1701.54 86.35 436.66 613.05 2656.67 447.44 36.31 6 W032s-1-WBDM 36.41 1551.48 115.27 4734.29 817.57 2628.78 388.96 44.32 7 W003s-2A-WBDM 33.42 1351.55 194.06 1551.16 620.00 37.92 8 W023s-1-WBDM 12.46 45.35 1961.59 201.28 1965.62 457.46 9 W033s-2A-WBDM 13.34 43.85 1801.87 197.25 2011.74 505.62 25.46
Table A.31 Peak Areas of Waste Oil Ethyl Ester From Its Respective Fatty Acids.
Samples 7.81 8.3 9.04 9.37 10 10.37 10.93is 11.11 1 1.6 11.86 12.02
Peak Areas (mvs-1 ) 1 W001p-3-WBDE 16.22 47.89 2056.50 9.78 190.21 0.00 1756.81 329.88 15.33 1.48 4.00 2 W021p-3-WBDE 11.94 27.31 1202.62 8.83 122.08 0.00 1097.86 214.67 8.78 1.80 2.54 3 W031p-3-WBDE 8.56 31.95 1319.59 56.63 149.69 0.00 1159.60 213.04 7.69 3.36 4.66
4 W002s-3-WBDE 4.48 23.06 874.01 50.44 162.70 159.54 1033.52 182.88 6.83 7.18 4.84 5 W022s-3-WBDE 2.94 19.14 812.12 45.50 199.32 262.89 1167.07 182.52 9.44 8.90 4.31 6 W032s-3-WBDE 5.36 25.72 861.78 43.45 178.32 185.65 1154.98 185.79 8.78 6.23 7.98
7 W003s-3-WBDE 11.41 34.54 1320.66 9.54 181.98 0.00 1452.92 597.88 13.86 28.55 5.19 8 W023s-3-WBDE 11.48 39.70 1635.42 3.02 164.40 2.62 1586.98 377.43 14.41 7.26 5.42 9 W033s-3-WBDE 9.00 29.87 1214.92 4.35 131.92 2.68 1318.26 315.55 12.77 11.60 4.93
Appendix
189
Methyl Oleate
Ethyl esters of Waste Oil
Chromatogram: W033s-3-WBDE
Figure A.1 GC chromatogram of waste oil ethyl ester
Methyl oleate
Chromatogram of methyl ester of waste oil from synthetic method 1:
Figure A.2 GPC chromatogram of waste oil methyl ester
5.00
5.05
5.10
5.15
5.20
5.25
5.30
5.35
5.40
7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0
7.76 8.25
8.99
10.06
10.42
10.99
11.49
11.74
11.90
Methyl Oleate
Appendix
190
Methyl laurate
Chromatogram of coconut oil methyl ester from synthetic method 1:
Figure A.3 GPC chromatogram of coconut oil methyl ester synthesized using method 1.
Chromatogram of coconut oil methyl ester from synthetic method 2A:
Figure A.4 GPC chromatogram of coconut oil methyl ester synthesized using method 2A.
Methyl Laurate
Methyl Laurate
Appendix
191
Chromatogram of coconut oil methyl ester from synthetic method 2B:
Figure A.5 GPC chromatogram of coconut oil methyl ester synthesized using method 2B.
Ethyl oleate Chromatogram of waste oil ethyl ester from synthetic method 3 :
Figure A.6 GPC chromatogram of waste oil ethyl ester synthesized using method 3.
Methyl Laurate
Ethyl oleate
Appendix
192
Ethyl laurate
Chromatogram of coconut oil ethyl ester from synthetic method 2A:
Figure A.7 GPC chromatogram of coconut oil ethyl ester synthesized using method 2A.
Chromatogram of coconut oil ethyl ester from synthetic method 2B:
Ethyl laurate
Ethyl laurate
Appendix
193
Figure A.8 GPC chromatogram of coconut oil ethyl ester synthesized using method 2B.
Chromatogram of coconut oil ethyl ester from synthetic method 3:
Figure A.9 GPC chromatogram of coconut oil ethyl ester synthesized using method 3.
Ethyl laurate