biosorption fyp updated2

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THERMODYNAMIC STUDIES ON BIOSORPTION OF ZINC USING PALM

SHELL ACTIVATED CARBON

KAYATHRE A/P RAVEENDRAN

A project report submitted in partial fulfilment of the

requirements for the award of Bachelor of Engineering

(Hons.) Chemical Engineering

Faculty of Engineering and Science

Universiti Tunku Abdul Rahman

April 2012


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DECLARATION

I hereby declare that this project report is based on my original work except for

citations and quotations which have been duly acknowledged. I also declare that it

has not been previously and concurrently submitted for any other degree or award at

UTAR or other institutions.

Signature : _________________________

Name : Kayathre A/P Raveendran

ID No. : 08 UEB 03125

Date : 13th

April 2012


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APPROVAL FOR SUBMISSION

I certify that this project report entitled THERMODYNAMIC STUDIES ON

BIOSORPTION OF ZINC USING PALM SHELL ACTIVATED CARBON

was prepared by KAYATHRE A/P RAVEENDRAN has met the required standard

for submission in partial fulfilment of the requirements for the award of Bachelor of

Engineering (Hons.) Chemical Engineering at University Tunku Abdul Rahman.

Approved by,

Signature : _________________________

Supervisor : Dr. Gulnaziya Issabayeva

Date : _________________________


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The copyright of this report belongs to the author under the terms of the

copyright Act 1987 as qualified by Intellectual Property Policy of University Tunku

Abdul Rahman. Due acknowledgement shall always be made of the use of any

material contained in, or derived from, this report.

2012, Kayathre a/p Raveendran. All right reserved.


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Specially dedicated to

my beloved grandmother, late Madam Alamaloo, mother, S.Chitra Devi and my

beloved father S.Raveendran.


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ACKNOWLEDGEMENTS

I would like to thank everyone who had contributed to the successful completion of

this project. I would like to express my gratitude to my research supervisor, Dr.

Gulnaziya Issabayeva for his invaluable advice, guidance and his enormous patience

throughout the development of the research.

In addition, I would also like to express my gratitude to my loving parents

especially my mom who is always on my side, riding along with me on my ups and

downs as well as giving me the encouragement to pursue my dreams and friends who

had helped and given me encouragement throughout my research.

To my dear friends, Thilaga Laxmy Kannan, Vitya Kalaiselvam, Sumithra

Shanmugam, Yushshendrra Shrii Kumar, Parameswari Subramaniam and all close

members in Faculty of Engineering & Science, UTAR thanks for making my stayed

in UTAR so colourful and enjoyable, the memory of your friendships will forever

stay inside my heart.


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THERMODYNAMIC STUDIES ON BIOSORPTION OF ZINC() USING

PALM SHELL ACTIVATED CARBON

ABSTRACT

Toxic heavy metals in air, soil, and water are global problems that are

growing threat to humankind. The heavy metals, which include copper (Cu), zinc

(Zn), lead (Pb), mercury (Hg), nickel (Ni), cobalt (Co), and chromium (Cr), are

common trace constituents in the earth crust. Heavy metals are major toxicants found

in industrial wastewaters. Thus, the removal of heavy metals from wastewater is

necessary before any unpleasant things occur. A conventional method for removing

metals from industrial effluents includes chemical precipitation, coagulation, solvent

extraction, electrolysis, membrane separation, ion exchange and adsorption. Most of

these methods are high capital and regeneration costs of the materials. Therefore,

there is currently a need for new, innovative and cost effective methods for the

removal of toxic substances from wastewaters. Bio-sorption is an effective and

adaptable method and can be easily adopted in low cost to remove heavy metals from

large amount of industrial wastewaters. Biosorption is a physicochemical process

that occurs naturally in certain biomass which allows it to passively concentrate and

bind contaminants (heavy metals) onto the biosorbent cellular structure. This project

is focused more on the phenomenon of biosorption in particular, on the biosorption

of zinc, where this entire assessment is about the thermodynamics studies on

biosorption of zinc by different type of biosorbent materials covering the effect of

different temperatures, effect of pH on biosorption capacity, and particle size of

biosorbent and initial concentration of zinc aqueous solution. At the same time, the

thermodynamics parameters such as change in standard free energy ( , enthalpy

( and entropy ( will be determine using several equations.


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TABLE OF CONTENTS

DECLARATION ii

APPROVAL FOR SUBMISSION iii

ACKNOWLEDGEMENTS vi

ABSTRACT vii

TABLE OF CONTENTS viii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF SYMBOLS/ABBREVIATIONS xii

LIST OF APPENDICES xiii

CHAPTER

1 INTRODUCTION 1

1.1 Background 1

1.2 Aims and Objectives 2

2 LITERATURE REVIEW 3

2.1 Background 3

2.2 Effect of agitation speed and contact time 4

2.3 Effect of pH on the biosorption capacity 5

2.4 Temperature Effect 6

2.5 Initial concentration of Zinc 6

3 METHODOLOGY 10

3.1 Preparation of Biosorbents 10


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3.2 Preparation of stock solution, Zn(NO3)2 and blank solution,

NaNO3 10

3.3 Biosorption Experiments 11

3.3.1 Batch Experiment 11

3.3.2 Analytical Experiment 11

3.4 Adsorption Equilibrium Models 12

3.4.1 Langmuir Isotherm 12

3.4.2 Freundlich Isotherm 13

3.5 Biosorption Thermodynamics 14

4 RESULTS AND DISCUSSION 15

4.1 The Effect of initial zinc ion concentration 15

4.2 The Effect of Temperature 17

4.3 Adsorption Equilibrium Models 19

4.3.1 Langmuir Isotherm 20

4.3.2 Freundlich Isotherm 23

4.4 Thermodynamics properties for biosorption of Zinc() by

original PSAC 26

4.5 Comparison of biosorption of Zinc(II) with different

Adsorbents Reported in Literature 29

4.6 Comparison of pH changes for biosorption of Zinc() with

different adsorbent were revised 30

5 CONCLUSION AND RECOMMENDATIONS 31

5.1 Conclusion 31

5.2 Recommendations 32

REFERENCE 33

APPENDICES 36


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LIST OF TABLES

TABLE TITLE PAGE

Table 2.1: The Langmuir Isotherm parameters for Biosorption of

Zinc () with different biosorbents. 8

Table 2.2: The Freundlich Isotherm parameters for Biosorption of

Zinc () with different biosorbents 8

Table 4.1: Sorption Capacity at different temperatures and initial

concentration 16

Table 4.2: Freundlich and Langmuir model parameters for

biosorption of zinc (11) with original PSAC 18

Table 4.3: Values of 1/T and ln b for the Gibbs Energy Graph 26

Table 4.4: Gibbs Energy for Biosorption of Zinc () ions on

original PSAC 27

Table 4.5: The thermodynamics parameters for the entire

Biosoprtion of Zinc () ions on original PSAC 28

Table 4.6: Zinc() adsorption capacities (qm) of agricultural

waste materials 29

Table 4.7: The biosorption of Zinc() in different pH with

different biosorbents 30


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LIST OF FIGURES

FIGURE TITLE PAGE

Figure 4.1: The Sorption Capacity for biosorption of Zinc ()

ions on PSAC at different temperatures 16

Figure 4.2: The Adsorption capacity of Zinc () ions during thebiosorption process by PSAC 17

Figure 4.3: Langmuir isotherm for biosorption of Zinc () ions

on original PSAC at T = 30C 20


on original PSAC at T= 40C 21


on original PSAC at T = 50C 21


on original PSAC at T= 60C 22

Figure 4.7: Freundlich isotherm forbiosorption of Zinc () ions

on original PSAC at T= 30 C 23

Figure 4.8: Freundlich isotherm for biosorption of Zinc () ions


Figure 4.9: Freundlich isotherm for biosorption of Zinc () ionson original PSAC at T= 50 C 24

Figure 4.10: Freundlich isotherm for biosorption of Zinc () ions


Figure 4.11:Thermodynamics parameters (The Gibbs Energy) forbiosorption of Zinc () ions on original PSAC 26


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LIST OF SYMBOLS/ABBREVIATIONS

b/K ratio of adsorption, L/mg

Ci initial concentration of zinc ions, mg/L

Ce final concentration of zinc ions, mg/L

Ceq equilibrium concentration of metal , mg/L

KF Freundlich constant of adsorption capacity, mg/g

M mass of biosorbent, g

n Freundlich constant of adsorption intensity

q metal uptake, mg/g

qmax maximum metal uptake, mg/g

R2

correlation coefficient

RL dimensionless equilibrium parameter for Langmuir Isotherm

R gas constant, J/(mol.K)

T temperature, K

V solution volume, mL

standard free energy, kJ/mol

enthalpy, kJ/mol

entropy, kJ/mol.K

PSAC palm shell activated carbon

rpm revolution per minute


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LIST OF APPENDICES

APPENDIX TITLE PAGE

A Graphs/Tables 36

Figure A1.1 Percentage uptake of biosorption of Zinc () ions

on original PSAC 36

Figure A1.2 The qegraph for biosorption of Zinc () ions on

original PSAC 37

Figure A1.3 Thermodynamic parameter for biosorption of Zinc

() ions on original 37


on original PSAC 38


original PSAC 38


() ions on original 39


on original 40


original PSAC 40

Figure A1.9 Thermodynamic parameter for biosorption of Zinc() ions on original PSAC(T = 50 C) 41

Figure A1.10 Percentage uptake of Zinc () ions on original

PSAC (T = 60 C) 42


original PSAC 42


() ions on PSAC 43


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Figure A1.13 Calibration graph for biosorption Zinc () ions on

original PSAC 43

Table A2.1 The Calibration table for the biosorption of Zinc() ions on PSAC 44

Table A2.2 Sorption Capacity for different temperatures as

initial concentration varies 44

Table A2.3 Adsorption capacity for different Temperature as

initial concentration varies 45

B Calculations for thermodynamic parameters 46


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CHAPTER 1

1INTRODUCTION

1.1 Background

Toxic heavy metals in air, soil, and water are global problems that are growing threat

to humankind. The heavy metals, which include copper (Cu), zinc (Zn), lead (Pb),

mercury (Hg), nickel (Ni), cobalt (Co), and chromium (Cr), are common trace

constituents in the earth crust. The metals concentrations in the ambient environment

have increased significantly since the Industrial Revolution.

Heavy metals are major toxicants found in industrial wastewaters. The

increment of population throughout nation, leads to a rapid industrialization.

Therefore, it increases the effluents and domestic wastewaters into the aquatic

ecosystem. High usage of heavy metals in industrial activities has caused the

discharge of them in wastewater. The discharge of metallic ions in industrial wastage

is of great concern because their presence and accumulation have a toxic effect on

living species. Industrial wastewater containing metal ions such as nickel, lead,

copper, zinc and aluminum are common because the metals are used in a large

number of industries such as electroplating, batteries manufacturing, mining, metal

finishing, brewery, and pharmaceutical.

Heavy metal toxicity can result in damaged or reduced mental and central

nervous function, lower energy levels, and damage to blood composition, lungs,

kidneys, liver, and other vital organs (International Occupational Safety and Health

Information Centre, 1999). Thus, the removal of heavy metals from wastewater is

necessary before any unpleasant things occur.


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One of the gears that help to achieve the removal of heavy metal is by using

activated carbon. A conventional method for removing metals from industrial

effluents includes chemical precipitation, coagulation, solvent extraction, electrolysis,

membrane separation, ion exchange and adsorption.

Most of these methods are at high capital and regeneration costs of the

materials. Therefore, there is currently a need for new, innovative and cost effective

methods for the removal of toxic substances from wastewaters. Bio-sorption is an

effective and adaptable method and can be easily adopted in low cost to remove

heavy metals from large amount of industrial wastewaters.

1.2 Aims and Objectives

General Objective

The general objective of this experiment is about the thermodynamics studies on

biosorption of zinc by original Palm Shell activated carbon.

Specific Objectives

The specific objectives for this experiment are to investigate:

1. The biosorption of zinc using palm shell activated carbon.

2. The effect of biosorption of zinc using palm shell activated carbon at four

different temperature. (30 , 40 50 and 60)

3. The effect of biosorption of zinc using palm shell activated carbon at

different range of initial concentration of zinc.

4. The thermodynamics parameters such as change in standard free energy

(, enthalpy ( and entropy ( for the biosorption of zinc using

palm shell activated carbon.


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CHAPTER 2

2LITERATURE REVIEW

2.1 Background

This entire review is about the thermodynamics studies on biosorption of zinc by

different type of biosorbent materials covering the effect of different temperatures,

effect of pH on biosorption capacity, biosorption time, and particle size of biosorbent

and initial concentration of zinc aqueous solution. Also the review encloses the

effects of different condition for biosorption and some methodological aspects.

This chapter is focused more on the phenomenon of biosorption in particular,

on the biosorption of zinc. Heavy metals are common in industrial application such

as manufacturing of pesticides, batteries, alloys, electroplating metal parts, textile

dyes, and steel. Zinc is one of the most crucial metals often found in effluents

discharged from manufacturing industries. Elimination of heavy metal by biosorption

plays an important part in wastewater treatment. Biosorption is a physicochemical

process that occurs naturally in certain biomass which allows it to passively

concentrate and bind contaminants onto the biosorbent cellular structure. The

scientists and engineers hope, this remedy will provide an economical alternative for

removing toxic heavy metals from industrial wastewater. The adsorbing biomass, or

biosorbents, can remove harmful metals like: arsenic, lead, cadmium, cobalt,

chromium, zinc and uranium. Biosorption can be used as an environmentally friendly

filtering technique. There is no uncertainty that the world could benefit from more


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precise filtering of harmful pollutants created by industrial processes. Biosorption

uses biomass raw materials which are either abundant or wastes from other industrial

operations. The metal-sorbing performances of certain types of biomass depend on

the type of biomass, the mixture in the solution, the type of biomass preparation, and

the chemico-physical environment. These studies enclose the biosorption of heavy

metal zinc using maize leaf, egg shell powder, chicken feather, fungal biomass,

wheat based biosorbent, rice husk, and activated carbon (Jonathan Fabrito & Aline

Nathasiah,2009).The effect of different operating parameters such as initial

concentration of zinc and adsorbent, temperature, particle size, effect of pH on the

biosorption capacity, effect of agitation speed, contact time and mass on the uptake

of zinc ions by biosorbents are enfold in this review. In addition, the biosorption

equilibrium thermodynamic parameters for the removal of zinc using those

biosorbents as mentioned above are enlighten in this review as well.

2.2 Effect of agitation speed and contact time

The agitation speed is required to enhance the chemical reaction by the biosorbent

with the zinc ions. As the agitation speed increases, the movement of the biosorbent

and the zinc ions increases as well, where it ensures the biosorbent and the zinc ions

collide together. Hence, the zinc ions will bind on the cellular structure of the

biosorbents. It is obvious that the removal efficiency of zinc ions increases

extensively at agitation speed between 100 rpm and 350 rpm (Shuguang Lua et al.,

2007).

In addition, contact time also plays a part for the removal efficiency of zinc

ions, where as the contact time increases the highest removal of zinc ions is achieved.

The contact time for each biosorbent to absorb the metal ions is depends on the

nature of the biosorbents. It is clearly illustrated by P.King et al., where the optimum

time for the removal of zinc using biomassAzaclirachta Indica bark is at 45 minutes.

Further time increases, there are no significant change is observed. So for this

biosorbents the optimum time of 45 minute has been chosen for effective removal of

zinc ions. Similarly, Jin-Ho Joo et.al permits that highest biosorption of zinc ions


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was observed at after 30 minutes using bacteria biomass as the biosorbents. This

short time required for biosorption in accordance with the results given by other

authors showed that the maximum absorption of zinc was reached after 30 minutes.

Overall, at the beginning of the biosorbent is added to the metal solution, the reaction

will be very prompt within the first 5 minutes of contact. This is due to the high

initial concentration at the initial stage, where the binding site on the biosorbent

cellular structure is still empty.

2.3 Effect of pH on the biosorption capacity

It is acknowledged that biosorption of heavy metal ions by biosorbents depends on

the pH solution. The pH medium influences the solubility of metal ions and the

concentration of counter ions. In addition, the pH affects the speciation of metal ions

in solution and the metal binding sites on biosorbent surface. The both carboxyl and

hydrogen ions presence in the solution, depends on the pH value. As the pH value

increases, the amount of carboxyl ions presence will be increases as well and vice

versa for the amount of hydrogen ions. Since zinc ions are positively charged, it is

preferable that the surface of the biosorbent will have higher negative charge density.

On the other hand, at lower pH values zinc removal was inhibited, perhaps as a result

of the competition of between hydrogen ions and zinc ions on the sorption sites.

Therefore, the efficiency of biosorption of zinc ions can be observed at pH above 4

(Sibel Tunali and Tamer Akar, 2005). Similar results were also reported in literature

for different biomass system. (Y.Prasanna Kumar et al.)


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2.4 Temperature Effect

The temperature parameter is found to be an important tool for the sorption of zinc

ions dealing with the thermodynamics of the biosorption process. It is promptly

correlates to the kinetic energy of the zinc ions. Apart from that, an increase or

decrease in temperature will cause a change in the amount of zinc being absorbed by

the biosorbents. Temperature changes will affect a number of factors which are

important in heavy metal ion biosorption(T.Kutsal et al.). Some of the factors include:

i. the stability of the metal ion species initially placed in solution;ii. the stability of micro organism-metal complex depending on the biosorption

sites;

iii. the effect of temperature on the micro organism cell wall configuration;iv. the ionization of chemical moieties on the cell wall

The temperature has two major effects on the adsorption process. One is that

increasing the temperature will increase the rate of adsorbate diffusion across the

external boundary layer and in the internal pores of the adsorbate particles because

liquid viscosity decreases as temperature increase and the other one is that it effects

the equilibrium capacity of the adsorbate depending on whether the process isexothermic and endothermic (Al-Qodah).

2.5 Initial concentration of Zinc

The initial zinc concentration is one of the key to determine the efficiency in removal

of zinc ions. As the zinc concentration is increased, the uptake of zinc ions increases

as well for certain level only. An increase in the concentration of zinc ions would

cause more hydrogen ions to be released, hence causing the pH value to decrease.

This would consistently lead to decrease in biosorption efficiency at high zinc ions

concentration. The higher concentration of zinc ions makes the biosorption capacity

reached a saturation value, where it doesnt give any further changes with initial zinc

ions concentration. The review that done, for this part were found to be comparable

with many of the reported literature. (Shuguang Lua et al., 2007).


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2.1.5 Effect of biosorbent particle size

The size of the biosorbent will influence the biosorption capacity. As the particle size

increases, the surface area is reduced and, therefore the binding area is reduced as

well. So, it will results in lower value of biosorption as the particle size increases (M.

Tukaram Bai et al. 2010). Hence, a smaller biosorbent particle size with a larger

surface area is more preferable.

2.1.6 Biosorption Isotherm

The equilibrium of the biosorption process is often described by fitting the

experimental points with models (Gadd, et al. 1988) usually used for the

representation of isotherm adsorption equilibrium. The Langmuir isotherms equation

is valid for monolayer sorption onto surface containing finite number of identical

sorption sites which is described by the following equation

(2.1)

where q is milligrams of metal accumulated per gram of the biosorbent material; Ceq

is the metal residual concentration in solution; qmax is the maximum specific uptake

corresponding to the site saturation and b is the ratio of adsorption and desorption

rates. This is a theoretical model for monolayer adsorption. Another empirical model

for monolayer adsorption is the Freundlich Isotherm, which is represented by the

following equation

(2.2)

where KF (mg g1) and n are the Freundlich constants related to adsorption capacity

and adsorption intensity, respectively. The adsorption capacities of the adsorbents for

the biosorption of Zn (II) have been compared with those of other adsorbents

reported in literature and the values of adsorption capacities have been presented in

Table 2.1 and Table 2.2. The values reported in the form of monolayer adsorption

capacity. The experimental data of the present investigations are comparable with the

reported values. In this literature reviews studies, it is clearly shown that the

Langmuir Isotherm fits the best compared to the Freundlich Isotherm.


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Table 2.1: The Langmuir Isotherm parameters for Biosorption of Zinc () with

different biosorbents.

Biosorbents Langmuir Isotherm

b (L/mg) qmax (mg/g) R2 Reference

P.simplicissimum 0.025 77.52 0.992 Ting Fan et al.2007

Clarified Sludge 0.299 15.53 0.9971 Bhattacharya et al.

Activated

alumina

0.102 13.69 0.9932 Bhattacharya et al.

Neem Bark 0.047 13.29 0.9923 Bhattacharya et al.

Table 2.2: The Freundlich Isotherm parameters for Biosorption of Zinc () with

different biosorbents

Biosorbents Freundlich Isotherm

Kf(mg/g) n R2 Reference

P.simplicissimum 8.248 0.4 0.887 Ting Fan et al. 2007

Clarified Sludge 3.16 0.705 0.9964 Bhattacharya et al.

Activated alumina 1.34 0.701 0.9923 Bhattacharya et al.

Neem bark 0.687 0.755 0.9913 Bhattacharya et al.


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2.1.7 Thermodynamics of Biosorption

The recent study of biosorption of Zinc (II) Ions by Calymperes erosum were carried

out by N.A. Adesola Babarinde with the authors working mates .Thermodynamic

parameters were obtained by varying temperature conditions over the range of 21-

37 C by keeping other variables constant. The values of the thermodynamic

parameters such as enthalpy energy H, Gibbs energy, G and entropy energy S

describes the biosorption of zinc ions by Calymperes erosum. The biosorption

process can be regarded as a heterogeneous and reversible process at equilibrium.

The biosorption of zinc ions with different biosorbent will give negative value for

Gibbs energy at various temperatures and the negative value indicates the biosorption

is a feasible process (Ting Fan et al. 2007).


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CHAPTER 3

3METHODOLOGY

3.1 Preparation of Biosorbents

Palm shell activated carbon (PSAC) was provided by Bravo Green Sdn. Bhd. a

manufacturer of the material located in Kuching, Sarawak, Malaysia. The material is

obtained using steam in the physical activation process. Oil-palm shells of various

size fractions, namely 1.0-2.0, 2.0-2.8 and 2.8-4.0 mm were used for the preparation

of activated carbons. Detailed preparation procedures can be found elsewhere. Themass of palm shell activated carbon was measured in the range of 0.2495 mg to

0.2505 mg.

3.2 Preparation of stock solution, Zn(NO3)2 and blank solution, NaNO3

Stock solutions of zinc concentration 6539 mg/L was prepared by dissolving 14.87 g

of Zn (NO3)2 in 500 mL of blank solution. The blank solution, NaNO3 was prepared

by dissolving 63.75 g of NaNO3 in 5 L deionised water. The solution of zinc nitrate

was prepared using standard flasks. The range of concentration of the prepared metal

solutions varied between 10 and 200 mg/L. The solutions were prepared by diluting

the zinc stock solution, which were obtained by dissolving in blank solution. The pH

of the solutions was adjusted with 0.1M HCI and 0.1M NaOH.


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3.3 Biosorption Experiments

3.3.1 Batch Experiment

Batch biosorption equilibrium experiments were conducted in 250 mL

conical flasks at a constant agitation speed that is 220 rpm. The experiments were

carried out at four different temperatures, that were 30 , 40 50

and 60 for twelve sets readings of zinc concentration. The experiments were

carried out in duplicate, where the total number of samples will be collected are there

hundred sixty samples. The first run of experiment will be using the palm shell

activated carbon. Around 10 mL of samples solution is being transferred into the test

tube. The conical flasks that contain the sample are being placed inside the orbital

shaker overnight. After 24 hrs, the samples were filtrated, and collected in a test tube

for further analytical experiments lines.

3.3.2 Analytical ExperimentThe mixture samples of the zinc ions and original PSAC were before batch

experiment and after batch experiment were collected in a test tube. The

measurement of the initial and equilibrium metal ions concentrations was carried out

using ICP-OES (Optima 7000DV, Perkin Elmer).The amount of metal absorbed by

palm shell activated carbon was calculated from the differences between metal

quantity added to the biomass and metal content of the supernatant using thefollowing equation: Equilibrium sorption capacity, (mg/g)

(3.1)

Where is the metal uptake (mg/g), and are the initial and final metal

concentrations in the solution (mg/L), respectively, V the solution volume (mL) and

M is the mass of biosorbent (g).


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3.4 Adsorption Equilibrium Models

3.4.1 Langmuir Isotherm

The relationship between the PSAC and the zinc ions was quantified by fitting the

obtained sorption values to the Langmuir isotherm. In this case, the following form

of the Langmuir equation is applied in Equation 3.2

(3.2)Where qm is the maximum sorption uptake per unit mass of adsorbent in mg/g, Ce is

the equilibrium concentration of heavy metal ions in mg/L and b is the Langmuir

constant of sorption and desorption rate.

To get the equilibrium data, initial zinc

(II) concentration were varied while the adsorbent mass in each sample was kept

constant.

If the metal ions are taken up independently on a single type of binding site in

such a way that the uptake of the first metal ion does not affect the sorption of the

next ion, then the sorption process would follow the Langmuir adsorption isotherm.

(Mubashir Hussain Nasir et. al, 2007) A further analysis of the Langmuir equation

can be made on the basis of a dimensionless equilibrium parameter, RL (L.K. Koopal

et. al 1994) also known as the separation factor, given by

(3.3)

The value of RL lies between 0 and 1 for a favorable adsorption, while RL > 1

represents an unfavorable adsorption, and RL = 1 represents the linear adsorption,

while the adsorption operation is irreversible if RL =0.


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3.4.2 Freundlich Isotherm

The Freundlich isotherm equation describes the biosorption of zinc ions from

liquid to solid surface (PSAC) and assumes that the stronger binding sites are

occupied first and that the binding strength decreases with the increasing degree of

site occupation. The Freundlich isotherm assumes a heterogeneous surface with a

non-uniform distribution of heat of adsorption over the surface. This isotherm can be

described as equation 3.4.

(3.4)

where

= equilibrium metal uptake, mg/g

KF= Freundlich constant of adsorption capacity, mg/g

Ce = final concentration of zinc ions, mg/L

n = Freundlich constant of adsorption intensity

Equation 3.5 can be transformed into a linear equation form as follows:

(3.5)

Where, KF and n are physical constants of Freundlich adsorption isotherm. Also, KF

and n are indicators of adsorption capacity and adsorption intensity, respectively. The

slope and intercept of linear Freundlich equation are equal to n and ln KF,

respectively. If the n value is in the range of 0 < n < 1, it indicates a favorable

adsorption (M.Tukaram Bai et al, 2010).


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3.5 Biosorption Thermodynamics

The thermodynamics studies were carried out by conducting batch biosorption

experiments with different initial zinc concentrations and temperature. Samples were

taken at constant periods and analyzed for their zinc concentration. The values of the

thermodynamic parameters such as H, G and S describing zinc ions

biosorption by PSAC, were calculated using the thermodynamic equations described

below. The biosorption process can be regarded as a heterogeneous and reversible

process at equilibrium.

The thermodynamic parameter such as the Gibbs free energy change

indicates the degree of spontaneity of a process. A higher and negative value

indicates a more energetically favorable process. Therefore, it can be used to evaluate

the thermodynamic feasibility of the adsorption of zinc ions on PSAC. The Gibbs

free energy change of the sorption reaction is given by equation 3.6 and 3.7.

(3.6)

RT

H

R

SK

ln (3.7)

where

= standard free energy, kJ/mol

= enthalpy, kJ/mol

T= temperature, K= entropy, kJ/mol.K

K = equilibrium constant from Langmuir isotherm


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CHAPTER 4

4RESULTS AND DISCUSSION

4.1 The Effect of initial zinc ion concentration

The effect of initial zinc ion concentration on biosorption was studied at temperature30 C, 40 C, 50C and 60 C at pH 5 with a constant agitation speed of 220 rpm.

Figure 4.1 shows that all the curves have the same pattern for the initial zinc ion

concentration against the adsorption percentage, where the adsorption percentage

declined as the initial zinc ion concentration increased. The figure 4.1 and 4.2 shows

that the metal uptake increases and the percentage adsorption of zinc decreases with

increase in metal ion concentration at different range of temperature.

The increment of metal uptake was tabulated in table 4.1 at different range of

temperature and initial concentration of zinc ions. However, the percentage

adsorption of zinc ions on PSAC was decreased from 73.1 % to 36.12 %

(temperature 30 C). Though an increase in metal uptake was observed, the decrease

in percentage adsorption may be attributed to lack of sufficient surface area to

accommodate much more metal ions available in the solution. The percentage

adsorption at higher concentration levels shows a decreasing trend whereas the

equilibrium uptake of zinc displays an opposite trend.


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At lower concentrations, all zinc ions present in solution could interact with

the binding sites and thus the percentage adsorption was higher than those at higher

zinc ion concentrations. At higher concentrations, lower adsorption yield is due to

the saturation of adsorption sites. As a result, the purification yield can be increased

by diluting the aqueous solutions containing high metal ion concentrations.

Figure 4.1: The Sorption Capacity for biosorption of Zinc () ions on PSAC at

different temperatures

Table 4.1: Sorption Capacity at different temperatures and initial concentration

Varies

Ci, mg/L

qe , mg g-1

Temperature, C30 40 50 60

10 3.248 1.062 1.237 3.712

20 5.654 3.837 3.849 6.033

30 7.884 4.606 3.996 7.568

40 10.560 4.812 3.988 9.336

50 11.632 5.217 4.940 9.520

70 17.484 5.940 5.664 10.632

90 20.272 6.532 5.864 12.216

120 25.188 6.776 6.184 11.812150 27.088 8.204 5.520 15.120


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Figure 4.2: The Adsorption capacity of Zinc () ions during the biosorption process

by PSAC

4.2 The Effect of Temperature

Temperature is found to be an important parameter for the sorption of zinc ions

dealing with the thermodynamics of the biosorption process. The studies on

biosorption of Zinc with PSAC were carried out with four different temperatures

which were 30 C, 40 C, 50 C and 60 C. It is directly related to the kinetic energy

of the zinc ions. Temperature changes will affect a number of factors which are

important in heavy metal ion biosorption. Some of the factors include: (Sag, Y. and T.

Kutsal, 2000.)

a. The stability of the metal ion species initially placed in solution.b. The stability of micro organism-metal complex depending on the biosorption

sites;

c. The effect of temperature on the microorganism cell wall configuration;d. The ionization of chemical moieties on the cell wall.


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The both figure 4.1 and 4.2 at the pre shows the relationship of temperature

with adsorption percentage and the sorption capacity based on the initial zinc ions

metal concentration. Based on the Figure 4.1 it can be seen that for the adsorption of

zinc ions initially the uptake capacity increases in a linear way with rising

equilibrium concentration. Uptake capacity is eventually limited by the fixed number

of uptake active sites on the adsorbent and a resulting plateau can be observed. This

plateau would represent the maximum uptake capacity of the adsorbent for zinc ions

at different temperature values. From the below table 4.2 it was found that qmax for

zinc ions are 52.083, 8.503, 7.032 and 13.00 mgg1

at temperature values of 303, 313,

323 and 333 K, respectively.

Table 4.2: Freundlich and Langmuir model parameters for biosorption of zinc (11)

with original PSAC

Temperature

( K )Langmuir Isotherm Freundlich Isotherm

b (L/mg) qmax

(mg/g)

R2

RL Kf(mg/g) n R2

303

313

323

333

0.0163

0.118

0.137

0.220

52.083

8.503

7.032

13.000

0.9576

0.9775

0.9513

0.9635

0.229 -0.847

0.074 -0.735

0.033 -0.578

0.021-0.263

1.153

1.093

1.041

1.574

0.7075

0.4898

0.5438

0.0307

0.9739

0.8759

0.8009

0.9652

The initial zinc concentration may provide a driving force to overcome all

mass transfer resistances between the adsorbent and the adsorption medium. Hence

higher sorption capacities were obtained at higher initial concentrations of zinc point

up by T.Fan (2001). Figure 4.1 shows that the uptake capacity of zinc ions increases

as the temperature increases.

The entire experimental results for organic reaction of biosorption indicated

that adsorption of zinc ions was endothermic (29.72 kJ/mol). The increment in

temperature may lead to a swelling effect within the internal structure of adsorbent

enabling metal ions to penetrate further (Ozer, 2001). The rise in temperature wouldalso cause a rise in kinetic energy of sorbent particles.


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First, the collision frequency between sorbent and sorbate would increase,

this results in the enhanced sorption on to the surface of the sorbent. Second, at high

temperature due to bond rupture of functional groups on adsorbent surface there may

be an increase in number of active sorption sites, which may also lead to enhance

sorption with the rise in temperature (E.Malkoc et al., 2005)

4.3 Adsorption Equilibrium Models

The biosorption of Zn (II) was investigated as a function of concentration at different

temperatures in the range of 10

200 mgL using 0.2495 mg to 0.2505 mg of

adsorbent, 250 mL of adsorbate solution, and 24 hours shaking time at a shaking

speed of 220 rpm. The results indicated that the uptake of metal ions was above 60%

at low adsorbate concentrations (1090 mgL1

) and 6 % 59 % at high

concentrations (100200 mgL1). The equilibrium data for the adsorption of Zn(II)

on original Palm shell activated carbon (PSAC) was tested with two adsorption

isotherm models (Langmuir, and Freundlich, isotherm) among which two models

were found to be suitable for the Zn(II) adsorption.

The Langmuir isotherm model applied to the estimation of maximum

adsorption capacity corresponding to complete monolayer coverage on the PSAC

surface. The equilibrium models are extensively used to investigate the amounts of

zinc ions absorbed by a certain PSAC. The distribution of zinc ions between solution

and PSAC is a measure of the position of equilibrium and can be expressed by one or

more isotherms. The equilibrium distribution is important in determining the

maximum biosorption capacity. The Langmuir isotherm model was chosen toestimate the maximum adsorption capacity corresponding to complete monolayer

coverage on the biomass surface. The Freundlich model was chosen to estimate the

adsorption intensity of the biosorbent towards the biomass.


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4.3.1 Langmuir Isotherm

The isotherm represents the equilibrium relationship between the metal

uptake by the adsorbent and the final metal concentration in the aqueous phase,

showing the adsorption capacity of the adsorbent. The pH value of 5.0 was chosen as

the experimental condition for the determination of adsorption isotherms. All the

datas were fitted into Langmuir isotherm for all the four diffe rent temperature. The

Figure 4.3, Figure 4.4, Figure 4.5 and Figure 4.6 were generated from the Langmuir

isotherm respectively. The best-fit equilibrium model was determined based on the

linear regression correlation coefficient R2.

Figure 4.3: Langmuir isotherm for biosorption of Zinc () ions on original PSAC at

T = 30C


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T= 40C


T = 50C


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T= 60C

Here we consider Langmuir model with its main assumptions: (Leszek Czepirksi et

al.)

a. Adsorption only takes place only at specific localized sites on the surface andthe saturation coverage corresponds to complete occupancy of these sites.

b. Each site can accommodate one and only one molecular or atom.c. The surface is energetically homogeneous, and there is no interaction

between neighboring and adsorbed molecules or atoms.

d. There are no phase transitions.

The RL values calculated were between 0.229 and 0.847 (Table 4.2)

indicating highly favorable biosorption of Zn (II) on PSAC for temperature 303 K.

Overall, the entire inorganic reactions for different temperature is favorable and by

referring to the RL values in table 4.2, the biosorption of Zn (II) at temperature 333 K

gives the lowest range of RL, (0.021-0.263). This is due to the high temperature,

where the low range of RL value probably caused by a change in the texture of the

PSAC and a loss in the sorption capacity due to material deterioration. (Volesky,

2003)


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The validity of Langmuir isotherm suggests that adsorption is a monolayer

process and adsorption of all species requires equal activation energy. As Table 4.2

shows, b increases with increasing of temperature, indicating that adsorption of zinc

ions onto PSAC surfaces increases with temperature. The results also implied that the

affinity of the binding sites increased with temperature. (Moradi et al. ,2011) page.

4.3.2 Freundlich Isotherm

The results of present study indicates that the Freundlich model does not fit the

experimental data since the R2

values were 0.9739, 0.8759, 0.8009 and 0.9652,

respectively, for 303, 313, 323 and 333 K. Below are the figure 4.7, figure 4.8, figure

4.9 and figure 4.10 shows has the n value in the range of 0 < n < 1 for the biosorption

of zinc ions using original PSAC. Thus, the adsorptions for different temperature

with the variations of initial concentration of zinc are favorable.

Figure 4.7: Freundlich isotherm for biosorption of Zinc () ions on original PSAC at

T= 30 C


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T= 40 C


T= 50 C


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Figure 4.10: Freundlich isotherm for biosorption of Zinc () ions on original PSAC

at T= 60 C

Freundlich isotherm does not describe the saturation behavior of adsorbents.

Regarding the coefficients of Freundlich model, KF increased with temperature,

revealing that adsorption capacity increased with temperature. Like KF, n increased

with temperature as well. Since all n values obtained from the isotherms exceeded

unity, the zinc ions were favorably adsorbed onto PSAC surfaces. The highest values

of n were 0.7075 at 303K.These data indicate favorable adsorption. Refer to table 4.2.

For all cases, the Langmuir equation fits the experimental data better than the

Freundlich equation. This isotherm does not predict any saturation of the adsorbent

by the sorbate. Instead, infinite surface coverage is predicted, indicating multilayer

sorption on the surface.


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4.4 Thermodynamics properties for biosorption of Zinc() by originalPSAC

In the present study, thermodynamic parameters were obtained by varying

temperature conditions over the range 303-333 K and varying initial concentrations

by keeping other variables constant. Thermodynamic parameters were calculated to

confirm the adsorption nature of the present study. The thermodynamic constants,

free energy change G, enthalpy change, H and entropy change, S were

calculated to evaluate the thermodynamic feasibility of the process and to confirm

the nature of the biosorption process. Those parameters were evaluated using the

equation 3.6 and 3.7.

Table 4.3: Values of 1/T and ln b for the Gibbs Energy Graph

T (C)Temperature

(K)1/T K ln K

30 303 0.0033 0.8493 -0.1633

40 313 0.0032 0.9999 -0.0001

50 323 0.0031 0.9656 -0.0350

60 333 0.0030 2.8547 1.0490

Figure 4.11:Thermodynamics parameters (The Gibbs Energy) for biosorption

of Zinc () ions on original PSAC


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The thermodynamic parameters of enthalpy energy, H and entropy energy,

S were obtained from the slope and intercept of vant Hoff plot of ln K against 1/T

(Fig. 4.11 and table 4.3). The negative G values for Zn (II) at various temperatures

approved the adsorption processes were spontaneous, and the values ofG (Table

4.4) decreased with an increase in temperature, indicated that the spontaneous nature

of adsorption of Zn (II) were inversely proportional to the temperature. Enhancement

of adsorption capacity at higher temperatures may be attributed to the enlargement of

pore size and activation of the PSAC surface.

The biosorption process at temperature 303 K gives a positive value of Gibbs

energy of 0.8314 kJ/mol tabulated at table 4.4. The author thinks that the positive

value of Gibbs energy was because the process was non-spontaneous enough to give

a negative value of Gibbs energy.

Table 4.4: Gibbs Energy for Biosorption of Zinc () ions on original PSAC

Based from Figure 4.11, the enthalpy and entropy were evaluated by

multiplying the gas constant, R referring to the equation 3.7. Therefore, the values of

the entropy and enthalpy were 95.34 J/mol.K and 29.72 kJ/mol. The positive value of

enthalpy energy H, 29.72 kJ/mol illuminated the endothermic nature of zinc ions

biosorption.

The thermodynamic parameters for the biosorption of zinc ions using original

PSAC were tabularize in table 4.5. The positive value of entropy energy S, 0.095

kJ/mol.K suggested the increase randomness at the solid or solution interface during

the biosorption of zinc ions on PSAC.

Temperature

(K)

G

(kJ/mol)

Process

303 0.8314 Non feasible

313 -0.12 feasible

323 -1.08 feasible

333 -2.03 feasible


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As the temperature increases, the Gibbs free energy decreases with more

negative values, which it indicates the degree of spontaneity of the biosorption

process, and the more negative values reflect a more energetically favorable

biosorption process of zinc ions onto original PSAC. In addition, from the table 4.5

below, the Langmuir constant, b (L/mg) is proportional to the temperature, which

eventually gives a negative declining value of Gibbs energy. Since Gibbs energy

related to the spontaneous of the biosorption process, thus at higher temperature of

333 K the degree of spontaneity was higher due to the kinetic movement of the

PSAC and zinc ions increases as well.

Table 4.5: The thermodynamics parameters for the entire Biosoprtion of Zinc ()

ions on original PSAC

Temperature,

Kb (L/mg) R

2

H

(kJ/mol)

S

(kJ/mol)

G

(kJ/mol)

303 0.0163

0.6627 29.72 0.095

0.8314

313 0.1180 -0.12

323 0.1370 -1.08

333 0.2200 -2.03


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4.5 Comparison of biosorption of Zinc(II) with different AdsorbentsReported in Literature

The adsorption capacities of the adsorbents for the biosorption of Zinc(II) have been

compared with those of other adsorbents reported in literature and the values of

adsorption capacities have been presented in Table 4.6. The values reported in the

form of monolayer adsorption capacity. The experimental data of the present

investigations are comparable with the reported values. From the Table 4.6, it is

observed that palm shell activated carbon gives the highest adsorption capacity

compared to the other biosorbents. Another thing, the author thinks that the high

adsorption capacity for PSAC was due to the parameter of pH and agitation speed of

220 rpm during the biosorption of zinc ions.

Table 4.6: Zinc() adsorption capacities (qm) of agricultural waste materials

Biosorbent qm, mg/g Equilibrium Model Reference

PSAC 52.08 Freudlich,Langmuir Present Study

Sugar beet pulp 35.60 Freudlich Pehlivan et al.,2006

Almond husk activated carbon 35.34 Freudlich,Langmuir Hasar et al.

Bengal gram husk 33.81 Freudlich,Langmuir Saeed et al.Cassava waste 11.06 - Abia et al.

Peanut hulls 9.00 - Brown at al.

Coir Fibers 8.60 - Shukla et al.

Pecan Shell carbon 7.38 Freundlich Bansode et al

Banana peel 5.80 Freundlich Annadurai et al.

Barlew straw 5.30 - Larsen & Schierup

Orange peel 5.25 Freundlich Annadurai et al.

Cocoa shell 2.92 - Meunier et al.


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4.6 Comparison of pH changes for biosorption of Zinc() with differentadsorbent were revised

The biosorption of Zinc() ions with PSAC was carried out under pH 5. Based, on

the literature review studies, it was observed that the optimum pH range were 4 to 6

to achieve the maximum sorption capacity. The Table 4.9 indicates the optimum pH

for biosorption of Zinc() ions using different biosorbents. It is well known that the

pH value of the medium affects the solubility of Zinc ions and the concentration of

the counter ions, on the functional groups of the PSAC cell walls. A PSAC presents a

high content of ionizable groups (carboxyl groups) on the cell wall polysaccharides,

which makes it very liable to the influence of the pH value. As shown in Table 4.7

the uptake of free ionic zinc depends on pH. The biosorption of metallic zinc ion was

observed to increase with increase in pH up to a value of 6.

These functional groups from PSAC carry negative charges that allow the

functional cell wall components to be potential binding sites for cations (P.Yin et al,

1999). Since high proton concentration at lower pH, zinc ions uptake was decreased

because of the positive charge density on metal binding sites. Namely hydrogen ionseffectively compete with zinc ions to bind the sites. The negative charge density on

the PSAC surface increases with increasing in pH due to deprotonation of the metal

binding sites.

Table 4.7: The biosorption of Zinc() in different pH with different biosorbents

Biosorbent qmax ( mg/g) pH Reference

Syzygium cumini L. 35.84 6.0 N.Rakesh (2006)

A.indica bark 33.49 6.0 King et al.

PSAC 52.08 5.0 Present study

Tectona grandis 16.42 5.0 Prasanna Kumar

Activated carbon 31.11 4.5 Mohan et al.

Sargassum sp. 24.35 4.5 Erteves et al.


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CHAPTER 5

5CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion

The current study shows that the biomass of original Palm Shell Activated Carbon

was used as effective biosorbents for the biosorption of Zn (II) from aqueous solution.

The specific objectives of this study had been accomplished by carrying out the

experiment according to the methodology, and then the thermodynamics parameters

were evaluated based on the tabulated datas. The initial concentrations of zinc affect

the sorption capacity of PSAC. The sorption capacity is relative to the initial

concentration. The highest sorption capacity was achieved at temperature 303 K.Zinc biosorption by original PSAC was fitted well with the Langmuir and Freundlich

adsorption isotherms equations in the studied metal concentration range. The

thermodynamic parameters include H, G and S. Those parameters were

strongly affected by the temperature and initial concentration of zinc ions. The effect

of temperature clearly observed during the computation of Gibbs free energy, where

the temperature is proportional to the Gibbs energy. The positive value of H

(29.72 kJ/mol) indicates an endothermic process. Hence S (0.095 kJ/mol) has to be

positive value as well.


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5.2 Recommendations

The entire studies of thermodynamics properties for biosorption of zinc metal using

original palm shell activated carbon was successfully accomplished. As a conclusion,

the highest adsorption capacity (73.1 % ) for biosorption of zinc metal using original

PSAC was achieved at temperature 303 K with the initial concentration of 10 mg/L.

For this present study, the Gibbs energy obtained at temperature 303 K is a positive

value, where the reaction is not spontaneous. So, for further studies in future, it is

recommended to decrease the initial concentration of zinc metal, to attain an

adsorption capacity of above 90% or even up to 100 % and to carry out at the same

temperature again. In addition, other parameters can be adjusted to obtain a higher

adsorption capacity.

Since, this study of using original PSAC manage to obtain adsorption

capacity of 73.1%, it is a good option to replace the original PSAC with the

biomodified PSAC in future studies, so that the sorption capacity of zinc can be

increase. Furthermore, base on the literature review studies and present work, at pH

range of 5 to 6 the biosoprtion of zinc will be at the optimum stage. Hence, it isanother alternative way to increase the sorption capacity of zinc by increasing the pH

value to 5.5 or 6.


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Jin-Ho Joo 1, S. H.-E. (2010). Comparative study of biosorption of Zn by Pseudomonas

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APPENDICES

APPENDIX A1: Graphs

Temperature 30 C

Figure B1.1: Percentage uptake of biosorption of Zinc () ions on original PSAC

(T = 30 C)


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Figure C1.2: The qegraph for biosorption of Zinc () ions on original PSAC

(T = 30 C)

Figure D1.3: Thermodynamic parameter for biosorption of Zinc () ions on original

PSAC (T = 30 C)


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Parameter: Temperature 40 C

Figure E1.4: Percentage uptake of biosorption of Zinc () ions on original PSAC

(T = 40 C)

Figure F1.5: The qegraph for biosorption of Zinc () ions on original PSAC (T = 40 C)


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Figure G1.6: Thermodynamic parameter for biosorption of Zinc () ions on original

PSAC(T = 40 C)


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Figure H1.7: Percentage uptake of biosorption of Zinc () ions on original

PSAC(T = 50 C)

Figure I1.8:The qegraph for biosorption of Zinc () ions on original PSAC

(T = 50 C)


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Figure J1.9: Thermodynamic parameter for biosorption of Zinc () ions on original

PSAC(T = 50 C)


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Figure K1.10: Percentage uptake of Zinc () ions on original PSAC (T = 60 C)

Figure L1.11: The qegraph for biosorption of Zinc () ions on original PSAC

(T = 60 C)


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Figure M1.12: Thermodynamic parameter for biosorption of Zinc () ions on PSAC

(T = 60 C)

Figure N1.13: Calibration graph for biosorption Zinc () ions on original PSAC

(T = 60 C)

R = 1

0200000

400000

600000

800000

1000000

1200000

1400000

0 200000 400000 600000 800000 1000000 1200000 1400000

Correctedi

ntensity

Net intensity


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APPENDIX O2: Tables

Table P2.1: The Calibration table for the biosorption of Zinc () ions on PSAC

Table Q2.2: Sorption Capacity for different temperatures as initial

concentration varies

Solution Net intensity Corrected intensity

Blank solution 59.9 59.9

Standard

1:10ppm

59327.6 59267.7

Standard

3:50ppm

288304.8 288244.9

Standard

3:100ppm

594518.7 594458.8

Standard

3:150ppm

914531.3 914471.4

Standard

3:200ppm

1238441.2 1238381.2

qe , mg g-1

Ci, mg/L Temperature, C

30 40 50 60

10 3.248 1.062 1.237 3.712

20 5.654 3.837 3.849 6.03330 7.884 4.606 3.996 7.568

40 10.560 4.812 3.988 9.336

50 11.632 5.217 4.940 9.520

70 17.484 5.940 5.664 10.632

90 20.272 6.532 5.864 12.216

120 25.188 6.776 6.184 11.812

150 27.088 8.204 5.520 15.120


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Table R2.3: Adsorption capacity for different Temperature as initial concentration

varies

Adsorption %

Concentration,ppm Temperature,C

30 40 50 60

10 73.1 66.94 57.15 72.89

20 65.89 60.45 63 64.05

30 63.23 58.42 59.28 56.33

40 59.57 56.59 53.15 53

50 59.33 56.07 52.23 43.64

70 62.35 40.1 42.92 35.95

90 54.56 26.63 31.93 31.23

120 48.89 26.45 26.62 21.38

150 46.54 26.22 9.24 14.74

170 46.39 23.75 8.73 15.74


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APPENDIX S: Calculations for thermodynamic parameters

Sample Calculation

Temperature 303 K

1. Langmuir Isotherm

From the Figure 4.3 the equation obtain from the graph is

Compare the above equation with equation 4.1:

From the comparison we can evaluate the b and qm value.

Gradient from the figure 4.3,

;

Then evaluate the b value,

Next, evaluate the dimensionless equilibrium parameter, RL from equation 4.2

Co = 11.259 mg/L

b = 0.0163 L/mg


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2. Freundlich Isotherm

From the Figure 4.3 the equation obtain from the graph is

Compare the above equation with equation 4.4

From the comparison of the two equations, need to evaluate the KF and n value.

Freundlich constant of adsorption intensity, n = 0.7075

Freundlich constant of adsorption capacity, KF =

so, KF = 1.153 mg/g

Thermodynamics Parameter

The parameter consists of Gibbs energy, entropy and enthalpy.

The Figure 4.11 was used to evaluate the above parameters. Figure 4.11 was plotted

according to the equation 4.6 :

This equation was obtained from the figure 4.11

Thus, we can evaluate the entropy and enthalpy.

Using gas constant, R = 8.314 J/mol.K

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