STUDY OF ESSENTIAL OIL DISTILLATION UNIT - CASE...

STUDY OF ESSENTIAL OIL DISTILLATION UNIT -

CASE STUDY FOR MENTHA CROP

RAJESH KATIYAR

CENTRE FOR RURAL DEVELOPMENT AND TECHNOLOGY

INDIAN INSTITUTE OF TECHNOLOGY DELHI

SEPTEMBER 2015

STUDY OF ESSENTIAL OIL DISTILLATION UNIT -

CASE STUDY FOR MENTHA CROP

by

RAJESH KATIYAR

Centre for Rural Development and Technology

Submitted

in fulfillment of the requirements of the degree of

Doctor of Philosophy

to the

INDIAN INSTITUTE OF TECHNOLOGY DELHI

SEPTEMBER 2015

Dedicated to My Parents

and my beloved Nisheet

i

Certificate

This is to certify that the thesis entitled “STUDY OF ESSENTIAL OIL DISTILLATION

UNIT - CASE STUDY FOR MENTHA CROP” being submitted by Mr. Rajesh Katiyar for

the award of the degree of DOCTOR OF PHILOSOPHY is a record of the original bonafide

research work carried out by him under my guidance and supervision at the Centre for Rural

Development and Technology, Indian Institute of Technology, Delhi. The work presented in this

thesis has not been submitted elsewhere either in part or full to any other University or Institute

for award of any degree or diploma.

(Professor S.N. Naik)

Centre for Rural Development & Technology

Indian Institute of Technology Delhi

Hauz Khas, New Delhi-110016, India

ii

Acknowledgements

It is my great honor to sincerely thank Prof. S. N. Naik for his valuable guidance, constructive

criticism, constant encouragement and help extended, whenever I approached him throughout

this research work. His research excellence and valuable analysis has really helped me in

extending my knowledge and learning skills.

I have been especially privileged one to receive valuable suggestions, analysis and constant

motivation from Prof. A. K. Gupta. Whenever I approached him, he has very happily spared his

valuable time in spite of his busy schedule. I sincerely thank Prof. K.K. Pant for his valuable

suggestions and constant encouragement during the period of my research. I extend my deep

appreciation for his support.

I am grateful to Prof. P.L. Dhar, Prof. Rajendra Prasad, Prof. Santosh, Prof. Satyawati Sharma,

Prof. V.K. Vijay, Dr. A. Malik, Dr. V.M.Chariar for their help provided immediately, whenever I

approached them.

I thank laboratory and office staff of the Centre for providing lab facilities and timely

requirements for my research work. I also thank Chemical Engg. Deptt. for providing TGA

facilities, and the staff of glass blowing workshop for their help.

The support received from QIP staff as well as library staff at IIT Delhi is really appreciable. I

also thank NISCAIR and INSDOC staff for their immediate help whenever I approached them.

I sincerely thank my Head of Department and Director at HBTI, Kanpur for sponsoring me for

my research program.

I very sincerely thank Shri H. N. Gogia, MD, Gogia Chemicals for providing me the GC and

GCMS facilities. I thank Meenakshi, Vibhana and other QC staff who joyfully spared their time

whenever I approached them though being very busy.

I sincerely thank and acknowledge Principal Director, FFDC, Kannauj and Director, FFDC,

Kanpur for allowing me to utilize their facilities and thank Mr. B. V. Shukla for his very

iii

generous help, whenever required. I thank their support staff for their immediate and prompt help

whenever approached.

I thank Shri S. K. Verma who helped me a lot during my field visits to his farms and distillation

units at village Barauli, Barabanki. I also thank Bihari, Deshraj, Pappu and Chotte who were

always with me whenever I visited and joined me in my travel and visits to all the adjoining

villages of the surrounding area.

I acknowledge and take the opportunity to thank Dr. R. K. Singh, Dr. Kiran Singh, Dr. Suman

and Mr. Paras for their constant motivation and good wishes. I thank Arushi, Anuroop and

Neeraj for their immediate support and help whenever required.

I thank Rambabu and Omprakash for their regular support, help and concern.

I feel pleased to acknowledge the help and good company received from Dipak, Narendra

Kumar, Pradhan, Prashant, Jadeja, Madhumita, Perminder, Narendra Sahoo, Lalit, Alok,

Pravakoor, Kiran, Sushil, Kanchan, Salil, Sunny, Sumant and Anil Verma.

I thank all my family members for their support and encouragement. They have motivated me a

lot and were very affectionate and considerate during the entire period of my research. I take the

opportunity to thank my wife Namita, daughter Ayushi and my son Suyash. I thank my parents,

for their moral support, love, great understanding, advice, motivation and help all throughout my

research work. I dedicate this thesis to my parents and my beloved nephew Nisheet Singh who

has made memorable contributions as Software Engineer during his tenure at Microsoft, USA.

New Delhi Rajesh Katiyar

iv

Abstract

Oil extracted from Mentha arvensis L., popularly known as corn mint, having menthol as a major

component is widely used in flavor, fragrance and pharmaceutical industry. Crop is aromatic

member of the Lamiaceae family whose essential oil is the richest source of natural menthol.

Around 225 x 10³ ha of land gets cultivated in the mint belt in geographical area of Indo-

Gangetic plains. The share of India in world mint oil market is around 55% to 60% and produces

around 35,000 metric ton of mint oil annually. Study of recovery of Mentha arvensis L. oil in

field level distillation units was done and process at laboratory level was studied. Both fresh as

well as partially dry crop was utilized for oil extraction. Process material balance identified the

loss routes of the essential oil during extraction. GC and GCMS analysis was done on the

capillary column under temperature programmed condition, and total 30 components were

identified. Laboratory, pilot plant level studies and mathematical modeling of kinetics of oil

recovery helped in identifying drawbacks of field level units. Possible utilization of by-products

of the process was explored, as 80% of the units used by small and medium farmers are water-

steam distillation type. This sector would be benefited by the results of the study carried out.

Water-steam distillation process is used extensively for essential oil extraction, and yield through

this process becomes important as oil is present in plant in low concentrations. Field level studies

provided information on the agricultural practices, process and operational details of the units

leading to identification of areas in which improvements were possible. Preliminary laboratory

distillation set-up similar to field unit, was utilized for extraction of oil. Clevenger set-up was

utilized at various stages to obtain oil content of the crop. Essential oil content determined by

v

Clevenger method under standard conditions for fresh crop was 0.83 ± 0.01%. Yields obtained

with water-steam distillation preliminary laboratory set-up was evaluated for its performance

with the help of the results obtained from standard procedure of Clevenger run for the crop of the

same lot. Process mass balance and composition analysis confirmed that oil which is not getting

extracted and remains with the crop is rich in menthol.

The main objective of the laboratory water-steam distillation modified set-up was to extract oil

from crop to a maximum value, reaching as near as oil content in the crop. In modified set-up,

around 1 g more oil was obtained from 1 kg of fresh crop in comparison to preliminary set-up.

Material balance results established that losses through various routes were reduced. Oil that was

extracted from modified set-up from fresh crop, contained menthol (77.01%) in good amount

and other major valuable components like menthone (5.15%), isomenthone (3.12%), menthyl

acetate (4.55%), neomenthol (2.63%) and isomenthol (0.32%) were in acceptable range along

with the other components qualitatively. Kinetic studies of the oil yield from fresh crop was

carried out keeping crop mass, feed water for steam generation, pack density of the crop

constant, and steam rate was varied. The amount of distillate water collected provided idea of

the steam utilized for the process. With the increase in steam rate, cumulative oil yield decreased.

Study on kinetics of oil yield from the partially dry crop revealed, that for nearly same steam

flow rate, partially dry crop provides around 15% more yield in comparison to fresh crop. For

partially dry crop, loss in drying was around 24%, cumulative oil yield was 0.795% and steam

rate was 0.75 ml/min. On the basis of drying studies and observations as well as results of

Clevenger runs, and oil yield obtained from modified set up, it was established that drying range

from 20% to 30% weight loss should be preferred. In the oil extracted from fresh crop, menthol

vi

was 77.01% and in the oil extracted from partially dry crop, menthol was 77.84%. As regards to

the remaining components, the difference was in very slight variation.

For the purpose of extension and verification of the laboratory level results that were obtained,

runs on pilot scale water-steam distillation unit were carried out. The unit was also utilized for

obtaining yield data and parameters to scale up to field level, and oil extraction was carried out

with partially dried crop as well as for fresh crop. Maximum oil extracted was 7.75 g per kg of

the crop for partially dried crop to the extent of 27.8% loss in weight. In fresh crop, oil extracted

was 6.96 g per kg of crop. At laboratory level, maximum oil extracted was 7.95 g per kg of crop

for partially dry crop whereas for fresh crop it was 6.72 g. The shade dried crop in all cases has

provided higher yield than the maximum yield obtained from fresh crop. Composition of major

components, β-pinene (0.76%), β-myrcene (0.61%), limonene (2.32%), menthone (5.06%),

isomenthone (3.63%), menthyl acetate (3.37%), neomenthol (2.90%) and menthol (77.58%) of

oil extracted from partially dry crop confirm to its good quality and meet the specifications of

IS 528 : 1999, that is, Oil of Mentha Arvensis – Specification. Oil has a very good percentage of

menthol content above 77%, meeting high commercial value.

The initial distribution of solute within the solid substrate influences selection of possible model

of essential oil extraction from a crop. Mint species have major portion of oil born on its surface

and essential oil storage in glandular trichomes on leaf surface is a feature of the family

Lamiaceae. To model the yield of Mentha arvensis L. essential oil extraction process from its

crop, model based on one-dimensional unsteady-state diffusion through flake particle (flat

geometry) was utilized. Experimental yield data on laboratory modified set up and pilot scale

vii

unit were used for validation of the model. Diffusivity, D value obtained for the water-steam

distillation pilot scale run was 1.02877x10ˉ¹¹ m²/s. Experimental results of Mentha arvensis L.

oil extraction yield agree very well with the flake particle based unsteady state diffusion model.

Study of different characteristics of the spent biomass obtained after oil extraction was carried

out for comparison with different agricultural residues to explore its feasibility in better use as

alternative renewable bio-fuel. Physical and chemical characteristics of spent biomass were

examined for calorific value, ash content, TGA and CHNS. Distillate water being other

important by-product of process was examined, for its oil content. Oil in distillate water was

recovered through solvent hexane. The composition analysis of oil recovered from distillate

water established that menthol (81.06%) was present in higher percentage in comparison to oil

that was extracted from fresh crop as well as from partially dry crop. For efficient runs, oil in

distillate water was on lower side. On basis of the study results and recommendations made

regarding minor modifications and better operation, an efficient operating procedure under

standard conditions of operating parameters, for an existing water-steam distillation field unit has

been suggested. This would result in around 50% water saving, 30% increase in oil yield,

minimum 1 hour saving in batch time and around 15% to 20% saving in fuel.

viii

CONTENTS _____________________________________________________________________________

Page No.

Certificate i

Acknowledgements ii

Abstract iv

Contents viii

List of Figures xiii

List of Tables xv

List of Plates xvii

CHAPTER – 1 INTRODUCTION 1-18

1.1 Background 1

1.2 Essential oil and its extraction 4

1.2.1 Essential oils 4

1.2.2 Essential oil extraction and fractionation 5

1.2.3 Theoretical aspects of distillation and distillation of miscible liquids 6

1.2.4 Distillation of two immiscible liquids 7

1.2.5 Isolation of the essential oil from the plant tissues 8

1.2.6 Classification of distillation techniques and their comparative application 9

1.2.6.1 Hydro-distillation 10

1.2.6.2 Water-steam distillation 11

1.2.6.3 Steam distillation 11

1.2.7 Utility of distillation techniques in relevance to cornmint oil 12

1.3 Need for study 14

1.4 Aim and Scope of present study 14

1.5 Objectives of present study 17

1.5.1 Main objective 17

1.5.2 Specific objectives 17

CHAPTER - 2 REVIEW OF LITERATURE 19-48

2.1 Status of cultivation and crop pattern of mint in north India 19

2.1.1 Cultivation and crop pattern adopted for cornmint 20

2.2 Nutrient management and oil biosynthesis 21

2.2.1 Glandular trichomes and their development 23

2.3 Oil content in mint species 24

2.3.1 Oil content in different mint species 25

ix

2.3.2 Oil content in different parts of cornmint 25

2.3.3 Plant age and oil content in Mentha arvensis L. 26

2.3.4 Optimum harvest time for Mentha arvensis L. 27

2.4 Preprocessing of the essential oil bearing crop before oil extraction 27

2.4.1 Preprocessing of Mentha longifolia L. 29

2.4.2 Preprocessing of Mentha piperita L. 30

2.4.3 Preprocessing of Mentha arvensis L. 31

2.5 Essential oil isolation techniques 32

2.5.1 Application of microwave heating in essential oil extraction 33

2.5.2 Application of additive in essential oil extraction 34

2.5.3 Distillation techniques in essential oil extraction 35

2.5.4 Essential oil extraction by distillation: Major factors affecting yield 37

2.5.4.1 Nature of essential oil components influencing distillation 38

process

2.5.4.2 Role of heat transfer in distillation process 40

2.6 Kinetic studies and mathematical analysis of process of essential oil isolation 41

2.6.1 Modeling essential oil extraction from plant species of Lamiaceae family 43

2.7 Spent biomass from aromatic crop: a potential category of lingo-cellulosic 44

biomass for better utilization

2.7.1 Conversions of biomass into products of utility 45

2.7.2 Utility of spent biomass of cornmint crop 46

2.8 Summary 46

2.8.1 Research gaps identified 47

CHAPTER – 3 FIELD LEVEL STUDIES 49-61

3.1 Agricultural practice and details of Mentha arvensis L. cultivation 50

3.1.1 Details of cultivar being used for plantation 52

3.1.2 Preprocessing and transportation of the crop 53

3.2 Process details for extraction of oil from crop 54

3.2.1 Process equipment details 54

3.2.2 Details of the procedure being followed 56

3.3 Limitations observed in the water-steam field distillation unit 59

CHAPTER – 4 EXPERIMENTAL 62-101

4.1 Materials and their preparation 62

4.1.1 Crop used for experiments 62

4.1.2 Harvesting and subsequent processing of the crop 63

x

4.2 Drying of the crop 65

4.2.1 Drying of the crop under ambient conditions 65

4.2.2 Loss of drying (in oven) 66

4.3 Estimation of moisture and oil content of the crop 66

4.3.1 Determination of moisture content in the crop 67

4.3.2 Clevenger distillation for determination of oil content in the crop 68

4.3.2.1 Description 68

4.3.2.2 Procedure and use of Clevenger set-up 68

4.4 Preliminary set up for water-steam distillation 69

4.4.1 Description 70

4.4.2 Procedure 71

4.5 Modified set-up for water-steam distillation 73


4.5.2 Procedure 78

4.6 Pilot scale water-steam distillation unit 80


4.6.1.1 Design of major components 82

4.6.2 Procedure 86

4.7 Material balance 92

4.7.1 Material balance utility 92

4.7.2 Material balance procedure 94

4.8 Analysis of the oil isolated 95

4.8.1 GC analysis of the oil samples 96

4.8.2 GCMS analysis of the oil samples 96

4.9 Analysis of biomass of Mentha arvensis L. 97

4.9.1 Determination of ash content in the biomass 98

4.9.2 Determination calorific value of the biomass 99

4.9.3 Thermo-gravimetric analysis (TGA) of the biomass 99

4.9.4 Elemental analysis of the biomass 100

4.9.5 Determination of extractives in biomass 101

4.10 Estimation of oil in the distillate water 101

CHAPTER – 5 RESULTS AND DISCUSSION 102-148

5.1 Preliminary laboratory set-up (water-steam distillation with 102

charge in overhead vessel)

5.1.1 Mass balance 103

5.1.2 Mass balance procedure and results 105

xi

5.1.3 Conclusions 107

5.2 Modified laboratory set-up (water-steam distillation with charge 108

in base vessel supported on packing)

5.2.1 Mass balance results 110

5.3 Discussion: Comparison of results 111

5.4 Composition of (extracted) essential oils: GC and GCMS analysis 112

5.4.1 Discussion: Composition of oils from preliminary and modified set-up 113

5.4.2 Quality of extracted essential oil from modified water-steam 114

distillation set-up

5.5 Effect of operating parameters on oil yield 117

5.5.1 Effect of steam rate 117

5.5.1.1 Effect of steam rate on the fresh crop 117

5.6 State of the crop used for extraction 120

5.6.1 Preliminary studies 120

5.6.2 Effect of partially drying the crop on oil yield 123

5.6.3 Chemical composition of the oil extracted from 125

partially dried crop

5.6.4 Comparative oil yield from partially dried crop 127

5.6.5 Comparative chemical composition of oil extracted from 128

fresh and partially dry crop

5.7 Pilot scale water-steam distillation unit 129

5.7.1 Oil extraction with partially dry crop 131

5.7.2 Yield data for the partially dry crop 132

5.7.3 Yield data for the fresh crop 132

5.7.4 Discussion: Oil yield for the fresh and partially dry crop 134

5.7.5 Comparative chemical composition of oil extracted from 136


5.8 Spent biomass 139

5.8.1 Ash content of the biomass 139

5.8.2 Calorific value of the biomass 140

5.8.3 (Thermo-gravimertric analysis) TGA of the biomass 141

5.8.4 Elemental analysis of the biomass 143

5.8.5 Extractives of the biomass 144

5.9 Distillate water 145

5.10 Extraction of essential oil from other plant materials: a comparison 146

5.11 Conclusions 147

xii

CHAPTER – 6 MASS TRANSFER STUDIES 149-165

6.1 Introduction 149

6.1.1 Distribution of solute in different particle types 149

6.1.2 Modeling essential oil extraction process 150

6.2 Aim of mass transfer studies 152

6.3 Mathematical Analysis of the Extraction Process 152

6.3.1 Diffusion from (flat geometry) flake particle model 152

6.4 Analysis of experimental data 156

6.4.1 Extraction of essential oil from Mentha arvensis L. crop 156

on the water- steam distillation laboratory set-up

6.4.2 Extraction of essential oil from Mentha arvensis L. crop on 159

the pilot scale water-steam distillation unit

6.5 Results obtained 163

6.6 Concluding remarks 165

CHAPTER – 7 SUMMARY, CONCLUSION AND RECOMMENDATIONS 166-185

7.1 Summary 166

7.1.1 Conclusions corresponding to objectives of research 173

7.2 Recommendations for the field units of water-steam distillation 178

7.2.1 General recommendations 178

7.2.2 Recommendations of minor modifications 179

7.2.3 Recommendations for better operation 181

7.2.4 Standard conditions of operating parameters 182

7.2 Recommendations for further work/ study 185

References 186-194

Appendices 195-210

Bio-data 211

xiii

LIST OF FIGURES

Page No.

Figure 1.1 Cultivation of Mentha arvensis L. in the areas of Indo-Gangetic

plains

16

Figure 4.1 Water-steam distillation with charge in overhead vessel 70

Figure 4.2 Water-steam distillation with charge in base vessel supported

on packing

74

Figure 4.3

Design drawing of the modified set-up for water-steam

distillation

77

Figure 4.4 Design drawing of pilot scale water-steam distillation unit 81

Figure 4.5 General process flow diagram for carrying out MB 93

Figure 5.1 Yield for the fresh crop under different steam flow rates 119

Figure 5.2 Weight of the crop versus time under ambient drying 122

Figure 5.3 Comparative maximum yield from fresh and dry crop 124

Figure 5.4 Cumulative oil yield from partially dry crop 127

Figure 5.5 Kinetic data of the oil extracted 131

Figure 5.6 Comparison of cumulative oil yield for the fresh and dry crop 135

Figure 6.1 Plot of ln [1/1-E(t)] vs. Extraction time of oil from Mentha

arvensis L. crop on water-steam distillation laboratory set-up

157

Figure 6.2 Comparison of experimental and model predicted essential oil

yields on water-steam distillation laboratory set-up

159

Figure 6.3 Plot of ln [1/1-E(t)] vs. Extraction time of oil from Mentha

arvensis L. crop on pilot scale water-steam distillation unit

161

Figure 6.4 Comparison of experimental and model predicted essential oil

yields on pilot scale water-steam distillation unit

163

Figure 6.5 Yield curves of essential oil extraction from Mentha arvensis L.

by water-steam distillation: mathematical models and pilot

scale data

165

Figure 7.1 Operating procedures to be followed on water-steam field

distillation unit

184

xiv

Page No.

Figure A1.1

GC profile of run on laboratory water-steam distillation

preliminary set up

195

Figure A1.2 GC profile of run on laboratory water-steam distillation

modified set-up

196

Figure A1.3 GCMS profile of run on laboratory water-steam distillation

modified set-up

197

Figure A1.4 GC profile (peaks of major components) 198

Figure A1.5 GC profile of oil extracted from partially dry crop on water-

steam distillation pilot scale unit

199

Figure A1.6 GCMS profile of oil extracted from partially dry crop on water-

steam distillation pilot scale unit

200

Figure A1.7 GC profile of oil extracted from fresh crop on water-steam

distillation pilot scale unit

201

Figure A1.8 GCMS profile of oil extracted from fresh crop on water-steam

distillation pilot scale unit

202

Figure A1.9 GCMS profile of oil extracted from water-steam distillation unit

operating on field

203

Figure A1.10 GC profile of the oil extracted from distillate water 204

Figure A2.1 TGA profile of spent biomass from water-steam distillation

laboratory run

205

Figure A2.2 DTG profile of spent biomass from water-steam distillation

laboratory run

206

Figure A2.3 TGA profile of unprocessed crop biomass 207

Figure A2.4 DTG profile of unprocessed crop biomass 208

Figure A2.5 TGA profile of spent biomass after oil extraction process on

water-steam distillation pilot scale unit

209

Figure A 2.6 DTG profile of spent biomass after oil extraction process on

water-steam distillation pilot scale unit

210

xv

LIST OF TABLES

Page No.

Table 4.1 Details of the streams shown in the general PFD of Figure 4.5 93

Table 5.1 Representative run data (on preliminary laboratory set-up) 103

Table 5.2 Stream wise compositions before mass balance 104

Table 5.3 Stream wise compositions after mass balance 106

Table 5. 4 Representative run data (on modified laboratory set-up) 109

Table 5.5 Stream wise compositions after mass balance 110

Table 5.6 Comparative results obtained after material balance 111

Table 5.7 Comparative compositions after GC and GCMS analysis 114

Table 5.8 Composition of isolated oil from run with 0.66% yield on

water-steam distillation modified set- up

116

Table 5.9 Kinetic study of oil extraction with fresh crop 118

Table 5.10 Composition of oil with yield of 0.795% (partially dry crop) on

water-steam distillation modified set-up

126

Table 5.11 Comparative composition of major components of oil from


129

Table 5.12 Representative run data (partially dry crop) on pilot scale water-

steam distillation unit

130

Table 5.13 Yield data for the partially dry crop 133

Table 5.14 Yield data for the fresh crop 134

Table 5.15 Comparative composition of the oil extracted from partially dry

crop and fresh crop on water-steam distillation pilot scale unit

138

Table 5.16 CHNS analysis results 143

Table 5.17 Yields of the extractives of the biomass of Mentha arvensis L. 144

Table 5.18 Major components of trapped oil from distillate water 145

xvi

Page No.

Table 6.1 Experimental Data for extraction of oil from Mentha arvensis

L. crop on water-steam distillation laboratory set-up

156

Table 6.2 Analysis of Experimental Data by flake particle model on

water-steam distillation laboratory set-up

158

Table 6.3 Experimental Data for extraction of oil from Mentha arvensis

L. crop on pilot scale water-steam distillation unit

160

Table 6.4 Analysis of Experimental Data by flake particle model on pilot

scale water-steam distillation unit

162

xvii

LIST OF PLATES

Page No.

Plate 3.1 Mentha arvesnsis L. cultivation in village Barauli, District

Barabanki

51

Plate 3.2 Single shoot of Mentha arvensis L. cultivar 52

Plate 3.3 Water-steam distillation unit at field 55

Plate 3.4 Collection of distillate water from the field 58

Plate 3.5 Firing to carry out heating of the distillation still 58

Plate 4.1 Mentha arvensis L. plantation at FFDC, Kanpur 63

Plate 4.2 Storage of the crop before experiment 64

Plate 4.3 Separator used in process 72

Plate 4.4 Metal Pall ring packing 78

Plate 4.5 Loading of the crop 78

Plate 4.6 Pilot scale water-steam distillation unit 86

Plate 4.7 Harvesting of the crop 88

Plate 4.8 Shade dried crop 88

Plate 4.9 Self-supporting bottom grid 89

Plate 4.10 Loading of the still 89

Plate 4.11 Distillation being carried out 91

Plate 4.12 Unloaded still 91

Plate 4.13 Dried spent biomass 98

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