The thesis investigates the synthesis of polyol from rice bran oil (RBO) through epoxidation and hydroxylation reactions. There were three studies: 1) Optimization of RBO epoxidation using acetic acid found optimal conditions were 4.3 h, 63.8°C with conversion increasing with time and temperature. 2) Epoxidation kinetics using formic acid determined rate constants and activation energy of 22.6 kJ/mol. Optimal conditions were 4 h, 60°C. 3) Hydroxylation optimization found optimal conditions were 125.5 min, 49°C with hydroxyl value increasing quadratically with time and temperature.

1. The Synthesis of Polyol from Rice Bran Oil
(RBO) through Epoxidation and
Hydroxylation Reactions
by
Edy Purwanto
School of Chemical Engineering
The University of Adelaide
A thesis submitted for the degree of
Master of Engineering Science
July 2010

2. ii
Declaration
This work contains no material which has been accepted for the award of any other
degree or diploma in any university or other tertiary institution to Edy Purwanto and,
to the best of my knowledge and belief, contains no material previously published or
written by another person, except where due reference has been made in the text.
I give consent to this copy of my thesis when deposited in the University Library,
being made available for loan and photocopying, subject to the provisions of the
Copyright Act 1968.
The author acknowledges that copyright of published works contained within this
thesis (as listed below) resides with the copyright holders(s) of those works.
Conference paper:
E. Purwanto, Y. Ngothai, B. O’Neill, and K. Bremmell, ‘Optimization of
epoxidation reaction of rice bran oil using response surface methodology’,
Proceedings: Chemeca 2009-37th Australasian Chemical Engineering Conference,
The Institution of Engineers, Perth, Australia, 27–30 September 2009, ISBN: 0-
85825-823-4, CD-ROM.
I also give permission for the digital version of my thesis to be made available on
the web, via the University’s digital research repository, the Library catalogue, the
Australasian Digital Theses Program (ADTP) and also through web search engines,
unless permission has been granted by the University to restrict access for a period
of time.
Mr. Edy Purwanto : …………….
Date : 9 July 2010

3. iii
Summary
Polyurethanes are valuable polymers with a wide variety of applications. They are
normally produced from polyol feedstocks derived from petroleum. As petroleum is
a non-renewable resource, an alternative source of feedstock is sought. A potential
source is rice bran oil. However, far too little attention has been paid to the
utilization of rice bran oil as a potential raw material to produce polyol as it contains
unsaturated fatty acids that can be converted to polyol and is the by product of rice
milling process and available at very low cost.
There are two sequential processes to produce polyol from rice bran oil, namely the
epoxidation and hydroxylation reactions. In this work, the optimal conditions in the
epoxidation reaction were investigated using acetic acid and formic acid as oxygen
carriers in terms of reaction time and temperature. Furthermore, the reaction kinetics
were also determined using formic acid as an oxygen carrier in the epoxidation step.
Finally, the influence of reaction time and temperature in the hydroxylation step
were also investigated in this study.
In order to determine the optimal condition, the epoxidation reaction was performed
in a three neck flask with the use of acetic and formic acid as oxygen carriers. Result
shows that the conversion of iodine value increased with reaction time and
temperature when acetic acid was used as an oxygen carrier (peroxyacetic acid).
Interestingly, the oxirane content increased with reaction time and temperature then
declined after having achieved the optimal point. The optimal condition was
achieved at a reaction time of 4.3 h and a temperature of 63.8o
C by performing
response surface methodology.
The conversion of iodine value also displayed similar behaviour during the
epoxidation reaction when formic acid was used as an oxygen carrier (peroxyformic
acid), namely the conversion increased with reaction time and temperature. The
measured rate constants were 0.172h-1
(40o
C), 0.304h-1
(50o
C), 0.374h-1
(60o
C),
0.425h-1
(70o
C) and 0.492h-1
(80o
C). The activation energy was 22.6 kJ/mol and the
epoxidation reaction was pseudo-first order with respect to the concentration of

4. iv
double bonds in the oil. Interestingly, peroxyformic acid shows improved
performance as indicated by higher content of maximal oxirane content 3.26%
compared to peroxyacetic acid which is only 2.62%. The optimal condition with the
use of formic acid as an oxygen carrier was obtained at reaction time of 4 h and
temperature of 60o
C.
In the hydroxylation step, results indicate that the hydroxyl value of polyol was a
quadratic function of reaction time and temperature and the optimal condition was
achieved at a reaction time of 125.5 min and temperature of 49o
C, with maximal
hydroxyl value 161.5 mg KOH/g oil by performing response surface methodology.
The viscosity of polyol increased with reaction time and temperature and resulted in
polyol with viscosity in the range 29.9 – 95.3 cP. Temperature was found to have the
most significant effect on the viscosity of polyol.
The results of this study confirm the potential of rice bran oil as a feedstock for
synthesis of polyol and show that the optimal conditions in the epoxidation and
hydroxylation reactions are a key control variable to obtain a high quality of polyol.

5. v
Acknowledgement
I would like to express my appreciation to numerous people who have greatly
contributed and assisted me to complete this research study. In particular I would
like to acknowledge:
• Dr Yung Ngothai, School of Chemical Engineering, University of Adelaide,
as principal supervisor for the supervision, motivation, ideas, discussions,
experience in the class and the opportunity to conduct research in the
laboratory.
• A/Prof Brian O’Neill, School of Chemical Engineering, University of
Adelaide, as co-supervisor for the supervision, support, ideas, discussions
and guidance for design of the experiments and the use of response surface
methodology which is a new knowledge for me.
• Dr Kristen Bremmell, School of Pharmacy and Medical Sciences, University
of South Australia, as co-supervisor for the supervision, ideas and
discussions through this project.
• A/Prof Dzuy Nguyen, School of Chemical Engineering, University of
Adelaide for permission to access Rheology Laboratory and viscometer
device.
• Andrew Wright, Leanne Redding, Jason Peak and the workshop for
assistance in the laboratory, construction and modification of apparatus;
Thana Deawwanich for guidance to operate viscometer apparatus; Gideon
Bani Kuncoro and Kan Li my colleagues, for support, motivation, and any
discussions in the office.
I would like to dedicate this thesis to my wife, Nanik Hasanah and my son, Nawfal
Adiva Purwanto.
I hope this thesis would provide a great contribution to the community and satisfy
with the expectations of the related people.

6. vi
Table of Contents
Declaration ii
Summary iii
Acknowledgment v
Table of Contents vi
List of Figures ix
List of Tables x
Nomenclature xv
1 INTRODUCTION 1
2 LITERATURE REVIEW 3
2.1 Rice Bran Oil (RBO) 3
2.2 Epoxidation Reaction 6
2.3 Hydroxylation Reaction 9
2.4 Synthesis of Polyol 11
2.5 Response Surface Methodology 12
2.6 Key Research Questions 13
2.7 Research Objectives 15
2.8 Significant/Contribution to the Discipline 15
3 MATERIALS and METHODS 18
3.1 Materials 18
3.2 Epoxidation Reaction 18
3.3 Hydroxylation Reaction 20
3.4 Epoxidation Test 21
3.4.1 Iodine Value Analysis 21
3.4.2 Oxirane Oxygen Content Analysis 22
3.5 Hydroxylation Test 23
3.5.1 Hydroxyl Value Analysis 23
3.5.2 Viscosity Analysis 24
4 EXPERIMENTAL RESULTS and DISCUSSION 25
4.1 Epoxidation of RBO - Acetic Acid as an Oxygen Carrier
(1st
Study) 25
4.1.1 Experimental Design and Optimization of the
Epoxidation Reaction 25

7. vii
4.1.2 Statistical Analysis 27
4.1.3 Effects of Reaction Time and Temperature on
Reaction Conversion 30
4.1.4 Effect of Reaction Time and Temperature on
Oxirane Content 31
4.2 Epoxidation of RBO – Formic Acid as an Alternate
Oxygen Carrier (2nd
Study) 33
4.2.1 Effects of Reaction Time and Temperature on
the Conversion 33
4.2.2 Reaction Kinetics 35
4.2.3 Effects of Reaction Time and Temperature on
Oxirane Content 38
4.3 Hydroxylation of Epoxidized RBO (3rd
Study) 41
4.3.1 Experimental Design and Optimization of
the Hydroxylation Reaction 41
4.3.2 Statistical Analysis 42
4.3.3 Effects of Reaction Time and Temperature on
Hydroxyl Value 45
4.3.4 Effects of Reaction Time and Temperature on
Viscosity of Polyol 48
5 CONCLUSION 52
6 RECOMMENDATIONS FOR FUTURE RESEARCH 53
REFERENCES 54
Appendix A – Calculation of Epoxidation Reaction 58
Appendix B – Calculation of Hydroxylation Reaction 61
Appendix C – Epoxidation Using Acetic Acid as an Oxygen Carrier
(1st
Study) 63
C.1 Experimental Design 63
C.2 Determination of Iodine Value and Conversion 65
C.3 Oxirane Content 66
C.4 Determination of the Optimal Condition 67

8. viii
Appendix D – Epoxidation Using Formic Acid as an Oxygen Carrier
(2nd
Study) 69
D.1 Determination of Iodine Value and Conversion 69
D.2 Reaction Kinetics 73
D.3 Oxirane Oxygen Content 80
Appendix E – Hydroxylation of Epoxidized Oil 84
E.1 Experimental Design 84
E.2 Determination of Hydroxyl Value 85
E.3 Determination of the Optimal Condition 88
E.4 Determination of the Viscosity of the Polyol Products 89

9. ix
List of Figures
Figure 2-1 Structure of rice kernel 4
Figure 2-2 An epoxide 7
Figure 2-3 Epoxidation reaction 7
Figure 2-4 Ring opening mechanism using acid catalyst 10
Figure 2-5 Ring opening mechanism using base catalyst 10
Figure 2-6 Epoxidation reaction mechanism 11
Figure 2-7 Hydroxylation reaction mechanism 12
Figure 3-1 Experimental apparatus of epoxidation reaction 19
Figure 3-2 Experimental apparatus of hydroxylation reaction 20
Figure 4-1 Effects of reaction time (X1) and temperature(X2) on
reaction conversion for acetic acid as an oxygen carrier 30
Figure 4-2 Effects of reaction time (X1)and temperature (X2) on
oxirane content for acetic acid as an oxygen carrier 32
Figure 4-3 Effects of reaction time (t) on reaction conversion (X) for
formic acid as an oxygen carrier at different temperatures 34
Figure 4-4 Determination of activation energy for epoxidation using
formic acid as an oxygen carrier 37
Figure 4-5 Effects of reaction time (t) and temperature on oxirane content
(%) for formic acid as an oxygen carrier at different temperatures 39
Figure 4-6 Effects of reaction time (X1) and temperature (X2) on
hydroxyl value of polyol 46
Figure 4-7 Effects of reaction time (X1) and temperature (X2) on
viscosity of polyol 49
Figure 4-8 Sample of polyol produced 50
Figure D-1 Plot reaction time vs ln1/(1-X) at T = 40o
C 75
Figure D-2 Plot reaction time vs ln1/(1-X) at T = 50o
C 76
Figure D-3 Plot reaction time vs ln1/(1-X) at T = 60o
C 77
Figure D-4 Plot reaction time vs ln1/(1-X) at T = 70o
C 78
Figure D-5 Plot reaction time vs ln1/(1-X) at T = 80o
C 79
Figure D-6 Plot ln(k) vs 1/T 80

10. x
List of Tables
Table 2-1 Typical fatty acid composition (wt%) of RBO 6
Table 2-2 Physical and chemical characteristics of RBO 6
Table 4-1 The range and levels of variables used in the RSM procedure
to determine the optimum conditions for the epoxidation reaction
of RBO 26
Table4-2 CCD and response in terms of conversion and oxirane content
during the epoxidation of RBO 27
Table 4-3 Regression statistics for conversion and oxirane content
for epoxidation of RBO 28
Table 4-4 Analysis of variance (ANOVA) for conversion and
oxirane content for epoxidation of RBO 28
Table 4-5 Significance of regression coefficients for conversion of
epoxidation of RBO 29
Table 4-6 Significance of regression coefficients for oxirane content
of epoxidation reaction 29
Table 4-7 Rate constant value at different temperature for
epoxidation using formic acid 36
Table 4-8 The range and levels of variables for hydroxylation reaction 42
Table 4-9 CCD and response in terms of hydroxyl value and
viscosity of polyol 43
Table 4-10 Regression statistics for hydroxyl value and viscosity of polyol 44
Table 4-11 Analyses Of Variance (ANOVA) for hydroxyl value and
viscosity of polyol 44
Table 4-12 Significance of regression coefficients for hydroxyl value of polyol 44
Table 4-13 Significance of regression coefficients for viscosity of polyol 45
Table A-1 Fatty acid composition of rice bran oil 58
Table C-1 Range and levels of variables 64
Table C-2 Experimental design of epoxidation using acetic acid
as an oxygen carrier 64
Table C-3 Experimental results of iodine value & conversion 66
Table C-4 Experimental results of oxirane oxygen content 67

11. xi
Table D-1 Experimental results of Iodine Value (IV) and Conversion (%X)
at 40o
C 71
Table D-2 Experimental results of Iodine Value (IV) and Conversion (%X)
at 50o
C 72
Table D-3 Experimental results of Iodine Value (IV) and Conversion (%X)
at 60o
C 72
Table D-4 Experimental results of Iodine Value (IV) and Conversion (%X)
at 70o
C 72
Table D-5 Experimental Results of Iodine Value (IV) and Conversion (%X)
at 80o
C 72
Table D-6 Determination of k value at 40o
C 75
Table D-7 Determination of k value at 50o
C 75
Table D-8 Determination of k value at 60o
C 76
Table D-9 Determination of k value at 70o
C 77
Table D-10 Determination of k value at 80o
C 78
Table D-11 Calculation of activation energy 79
Table D-12 Experimental results of oxirane oxygen content at T = 40o
C 82
Table D-13 Experimental results of oxirane oxygen content at T = 50o
C 82
Table D-14 Experimental results of oxirane oxygen content at T = 60o
C 82
Table D-15 Experimental results of oxirane oxygen content at T = 70o
C 83
Table D-16 Experimental results of oxirane oxygen content at T = 80o
C 83
Table E-1 Range and levels of hydroxylation reaction 85
Table E-2 Experimental design of hydroxylation reaction 85
Table E-3 Saponification value prior to acetylation 86
Table E-4 Saponification value after acetylation 87
Table E-5 Hydroxyl value of polyol 88
Table E-6 Viscosity at shear rate 149.79 s-1
, t = 120 min and T = 30o
C 90
Table E-7 Viscosity at shear rate 135.04 s-1
, t = 120 min and T = 30o
C 90
Table E-8 Viscosity at shear rate 114.92 s-1
, t = 120 min and T = 30o
C 91
Table E-9 Viscosity at shear rate 95.03 s-1
, t = 120 min and T = 30o
C 91
Table E-10 Viscosity at shear rate 74.89 s-1
, t = 120min and T = 30o
C 91
Table E-11 Viscosity at shear rate 55.00 s-1
, t = 120 min and T = 30o
C 92
Table E-12 Viscosity at shear rate 29.95 s-1
, t = 120 min and T = 30o
C 92
Table E-13 Viscosity at shear rate 147.79 s-1
, t = 80 min and T = 40o
C 93

12. xii
Table E-14 Viscosity at shear rate 135.04 s-1
, t = 80 min and T = 40o
C 93
Table E-15 Viscosity at shear rate 114.92 s-1
, t = 80 min and T = 40o
C 93
Table E-16 Viscosity at shear rate 95.03 s-1
, t = 80 min and T = 40o
C 94
Table E-17 Viscosity at shear rate 74.89 s-1
, t = 80 min and T = 40o
C 94
Table E-18 Viscosity at shear rate 55.00 s-1
, t = 80 min and T = 40o
C 94
Table E-19 Viscosity at shear rate 29.95 s-1
, t = 80 min and T = 40o
C 95
Table E-20 Viscosity at shear rate 149.79 s-1
, t = 160 min and T = 40o
C 96
Table E-21 Viscosity at shear rate 135.04 s-1
, t = 160 min and T = 40o
C 96
Table E-22 Viscosity at shear rate 114.92 s-1
, t = 160 min and T = 40o
C 96
Table E-23 Viscosity at shear rate 95.03 s-1
, t = 160 min and T = 40o
C 97
Table E-24 Viscosity at shear rate 74.89 s-1
, t = 160 min and T = 40o
C 97
Table E-25 Viscosity at shear rate 55.00s-1
, t = 160 min and T = 40o
C 97
Table E-26 Viscosity at shear rate 29.95 s-1
, t = 160 min and T = 40o
C 98
Table E-27 Viscosity at shear rate 149.79 s-1
, t = 40 min and T = 50o
C 99
Table E-28 Viscosity at shear rate 135.04 s-1
, t = 40 min and T = 50o
C 99
Table E-29 Viscosity at shear rate 114.92 s-1
, t = 40 min and T = 50o
C 99
Table E-30 Viscosity at shear rate 95.03 s-1
, t = 40 min and T = 50o
C 100
Table E-31 Viscosity at shear rate 74.89 s-1
, t = 40 min and T = 50o
C 100
Table E-32 Viscosity at shear rate 55.00 s-1
, t = 40 min and T = 50o
C 100
Table E-33 Viscosity at shear rate 29.95 s-1
, t = 40 min and T = 50o
C 101
Table E-34 Viscosity at shear rate 149.79 s-1
, t = 120 min and T = 50o
C 102
Table E-35 Viscosity at shear rate 139.96 s-1
, t = 120 min and T = 50o
C 102
Table E-36 Viscosity at shear rate 110.01 s-1
, t = 120 min and T = 50o
C 102
Table E-37 Viscosity at shear rate 84.95 s-1
, t = 120 min and T = 50o
C 103
Table E-38 Viscosity at shear rate 74.89 s-1
, t = 120 min and T = 50o
C 103
Table E-39 Viscosity at shear rate 50.09 s-1
, t = 120 min and T = 50o
C 103
Table E-40 Viscosity at shear rate 25.05 s-1
, t = 120 min and T = 50o
C 104
Table E-41 Viscosity at shear rate 149.79 s-1
, t = 200 min and T = 50o
C 105
Table E-42 Viscosity at shear rate 135.04 s-1
, t = 200 min and T = 50o
C 105
Table E-43 Viscosity at shear rate 114.92 s-1
, t = 200 min and T = 50o
C 105
Table E-44 Viscosity at shear rate 95.03 s-1
, t = 200 min and T = 50o
C 106
Table E-45 Viscosity at shear rate 74.89 s-1
, t = 200 min and T = 50o
C 106
Table E-46 Viscosity at shear rate 55.00 s-1
, t = 200 min and T = 50o
C 106
Table E-47 Viscosity at shear rate 29.95 s-1
, t = 200 min and T = 50o
C 107

13. xiii
Table E-48 Viscosity at shear rate 149.79 s-1
, t = 80 min and T = 60o
C 108
Table E-49 Viscosity at shear rate 114.92 s-1
, t = 80 min and T = 60o
C 108
Table E-50 Viscosity at shear rate 74.89 s-1
, t = 80 min and T = 60o
C 108
Table E-51 Viscosity at shear rate 29.95 s-1
, t = 80 min and T = 60o
C 109
Table E-52 Viscosity at shear rate 135.04 s-1
, t = 80 min and T = 60o
C 109
Table E-53 Viscosity at shear rate 95.03 s-1
, t = 80 min and T = 60o
C 109
Table E-54 Viscosity at shear rate 55.00 s-1
, t = 80 min and T = 60o
C 110
Table E-55 Viscosity at shear rate 149.79 s-1
, t = 160 min and T = 60o
C 111
Table E-56 Viscosity at shear rate 135.04 s-1
, t = 160 min and T = 60o
C 111
Table E-57 Viscosity at shear rate 114.92 s-1
, t = 160 min and T = 60o
C 111
Table E-58 Viscosity at shear rate 95.03 s-1
, t = 160 min and T = 60o
C 112
Table E-59 Viscosity at shear rate 74.89 s-1
, t = 160 min and T = 60o
C 112
Table E-60 Viscosity at shear rate 55.00 s-1
, t = 160 min and T = 60o
C 112
Table E-61 Viscosity at shear rate 29.95 s-1
, t = 160 min and T = 60o
C 113
Table E-62 Viscosity at shear rate 149.79 s-1
, t = 120 min and T = 70o
C 114
Table E-63 Viscosity at shear rate 135.04 s-1
, t = 120 min and T = 70o
C 114
Table E-64 Viscosity at shear rate 114.92 s-1
, t = 120 min and T = 70o
C 114
Table E-65 Viscosity at shear rate 95.03 s-1
, t = 120 min and T = 70o
C 115
Table E-66 Viscosity at shear rate 74.89 s-1
, t = 120 min and T = 70o
C 115
Table E-67 Viscosity at shear rate 55.00 s-1
, t = 120 min and T = 70o
C 115
Table E-68 Viscosity at shear rate 29.95 s-1
, t = 120 min and T = 70o
C 116
Table E-69 Viscosity at shear rate 149.79 s-1
, t = 120 min and T = 50o
C 117
Table E-70 Viscosity at shear rate 135.04 s-1
, t = 120 min and T = 50o
C 117
Table E-71 Viscosity at shear rate 114.92 s-1
, t = 120 min and T = 50o
C 117
Table E-72 Viscosity at shear rate 95.03 s-1
, t = 120 min and T = 50o
C 118
Table E-73 Viscosity at shear rate 74.89 s-1
, t = 120 min and T = 50o
C 118
Table E-74 Viscosity at shear rate 55.00 s-1
, t = 120 min and T = 50o
C 118
Table E-75 Viscosity at shear rate 29.95 s-1
, t = 120 min and T = 50o
C 119
Table E-76 Viscosity at shear rate 149.79 s-1
, t = 120 min and T = 50o
C 120
Table E-77 Viscosity at shear rate 135.04 s-1
, t = 120 min and T = 50o
C 120
Table E-78 Viscosity at shear rate 114.92 s-1
, t = 120 min and T = 50o
C 120
Table E-79 Viscosity at shear rate 95.03 s-1
, t = 120 min and T = 50o
C 121
Table E-80 Viscosity at shear rate 74.89 s-1
, t = 120 min and T = 50o
C 121
Table E-81 Viscosity at shear rate 55.00 s-1
, t = 120 min and T = 50o
C 121

14. xiv
Table E-82 Viscosity at shear rate 29.95 s-1
, t = 120 min and T = 50o
C 122

15. xv
Nomenclature
E activation energy (kJ/mol)
k reaction rate constant (h-1
)
m mass (g)
n reaction orders
n moles number (mol)
N normality (N)
R gas constant (J/mol.K)
R2
correlation coefficient
SA saponification value after acetylation (mg KOH/g oil)
SB saponification value before acetylation (mg KOH/g oil)
t reaction time (h, for epoxidation reaction)
t reaction time (min, for hydroxylation reaction)
T temperature (K)
V volume (mL)
x real value of independent variables
X coded value of independent variables
X reaction conversion
Y response variables
Greek
x∆ step change value
ρ density (g/mL)
τ shear stress (Pa)
•
γ shear rate (s-1
)
µ viscosity (cP)
Abbreviations
ANOVA analysis of variance
DB double bonds
EO epoxidized oil
FA formic acid

16. xvi
FFA free fatty acids
HV hydroxyl value
IV iodine value
MMT million metric tons
MW molecular weight
PFA peroxyformic acid
PL phospholipids
PPO polypropylene oxide
RBO rice bran oil
RSM response surface methodology
US united states

17. 1
1 INTRODUCTION
Polyurethanes were first discovered by Professor Otto Bayer in 1973 and are used in
a wide variety of applications (Chian et al., 1998). They have been exploited as
coatings, thermoset and thermoplastic materials, adhesives and rigid or non-rigid
foams (Guo et al., 2006; Lligadas et al., 2006; Wang et al., 2009). Hence, the
worldwide demand for polyols is projected to increase each year. Polyurethanes are
generally produced from the reaction between polyols and diisocyanate (Pechar et
al., 2006). Polyols are normally derived from petroleum feedstocks and are known
as petroleum-based polyols (Tu et al., 2007). As the demand for polyols is
increasing whilst the amount of petroleum is declining, alternative raw material for
the production of polyols are needed.
Worldwide rice production is roughly 500 million metric tons (MMT) per year
(Jahani et al., 2008). Rice bran oil (RBO) is a by product of the rice milling process;
hence it cheap and readily available. RBO is a potential raw material that has not
been explored as feedstock to produce polyol. RBO is attractive as it contains
unsaturated bonds that can be converted to hydroxyl groups called polyols. Hence,
RBO can be used as a raw material for polyol production. To date, rice bran has
been used as a mixture of livestock food and as biomass fuel for boiler feed. The oil
content of RBO is in the range of 15 – 23 wt% (Zullaikhah et al., 2005). Hence,
RBO has enormous potential as it is a renewable resource and research needs to be
undertaken to develop and add value by converting the double bonds present in
RBO to produce polyols. Moreover, the production cost of polyols could be reduced
with the utilization of such by products and low priced feedstock.
Polyol can be produced by two consecutive reactions, namely epoxidation and
hydroxylation (Petrovic et al., 2003). During the epoxidation stage, the double bonds
in the vegetable oils are converted into epoxide (oxirane) groups whereas in the
hydroxylation stage, the epoxide groups are converted to hydroxyl groups. The
resulting product is a polyol as it contains more than one hydroxyl groups.

18. 2
In the epoxidation of rubber seed oil using peroxyacetic acid, the ring opening of
epoxide groups could be minimized when the epoxidation reaction was carried out at
an intermediate temperature of 50 – 60o
C. (Okieimen et al., 2002). In the
epoxidation of soybean oil using peroxyacetic acid followed by hydroxylation
reaction using methanol, the hydroxyl value of soy-polyol of 169 mg KOH/g oil
could be achieved whereas using olive oil as a raw material and m-
chloroperoxybenzoic acid, the hydroxyl value of polyol product was 138 mg KOH/g
oil (Petrovic et al., 2003). However, far too little attention has been paid to the
utilization of RBO as a potential raw material to produce polyol. Therefore, in the
synthesis of polyol from RBO, the optimal operating conditions in the epoxidation
and hydroxylation reactions have to be clearly defined to obtain a high quality of
polyol since different raw materials will have different characteristics. High quality
of polyol is indicated by high content of hydroxyl groups represented by hydroxyl
value.
The key goal of this project is to determine the optimal operating conditions for the
epoxidation and hydroxylation reactions to produce a polyol synthesized from rice
bran oil.

19. 3
2 LITERATURE REVIEW
This review will be divided into several parts. As mentioned in Chapter 1, the
composition of potential feedstock is a crucial factor for the successful synthesis of
polyol. Therefore, the first section will examine the potential of rice bran oil (RBO)
as raw material for synthesis of polyol. The next section will consider the synthesis
of polyol using epoxidation and hydroxylation reactions. As these reactions have
strong influence on the quality of polyol product, a review on epoxidation and
hydroxylation reactions will help to understand the process and contribution to
polyol product. Following this, response surface methodology (RSM) will be
discussed as a method to determine the optimal operating condition. Finally,
research questions, objectives and significance of this research will be discussed as
research direction and contribution of research topic to field area.
2.1 Rice Bran Oil (RBO)
Nowadays, polyol plays an important aspect as a raw material to produce
polyurethanes which have been widely used in polymer applications (Guo et al.,
2000, Hu et al., 2002, Lligadas et al., 2006, Wang et al., 2007). The demand for
polyol worldwide is predicted to increase each year. Generally, polyols are produced
from petroleum feedstocks. In recent years, interest has increased in the utilization
of vegetable oils as feedstock given environmental concerns and diminished
availability of raw materials for polyol production. Therefore, a number of
researchers have studied vegetable oils as alternative feedstock to substitute for
petroleum to provide sustainable development (Chen et al. 2002; Okieimen et al.,
2002; Petrovic et al., 2002 and 2003; Goud et al., 2006 and 2007; Setyopratomo et
al., 2006; Dinda et al., 2007; Benaniba et al., 2007; Ikhuoria et al., 2007; Lin et al.,
2008; Cai et al., 2008; Mungroo et al., 2008). One type of vegetable oils that can be
utilized as an alternative feedstock is rice bran oil (RBO). Hence, it needs to be
explored for various applications in particular polymer materials.
The term rice bran oil refers to the oil that comes from rice bran (Oryza sativa)
through an extraction process. Rice bran is a by product of rice milling process

20. 4
produced from the outer layer of rice kernel or during conversion of brown to white
rice. The rice kernel consists of endosperm, 70 – 72%; hull, 20%; bran, 7.0 – 8.5%;
and embrio, 2- 3% (Ju et al. 2005). The structure of rice kernel is illustrated in
Figure 2-1 below:
Figure 2-1 Structure of rice kernel (source www.ricebranoil.info)
Rice bran oil is widely used as cooking oil in numerous countries, in particular in
Indonesia, China, Japan, India and Korea. These countries have attractive and
productive agriculture especially for rice cultivation. Therefore, RBO is readily
available and develops for edible oil in food processing application since it offers
benefit for healthiness and rich on nutrition. RBO has different characteristic
compared to other oils in terms of its unsaponifiable matter.
Rice bran is a by product from the rice milling process. It is normally used as
biomass fuel for boilers or as a food source for animals. Therefore, effort is needed
to increase the added value of rice bran by extracting the oil content as it contains oil
in the range 15 – 23% (Zullaikhah et al., 2005). RBO can be utilized as a potential
raw material for synthesis of polyol since it contains double bond, readily available
and inexpensive raw material. The typical composition of RBO by weight percent
(wt%) is (Ghosh, 2007):
• Triglycerides : 81 – 84%
• Diglycerides : 2 – 3%
• Monoglycerides :1 – 2%
• Free fatty acids (FFA): 2 – 6%
• Wax : 3 – 4%
• Glycolipids : 0.8%
NOTE:
This figure is included on page 4
of the print copy of the thesis held in
the University of Adelaide Library.

21. 5
• Phospholipids (PL) : 1 – 2%
• Unsaponifiable matter: 4%
The unsaturated fatty acid content in the oil is an important factor for synthesis of
polyol as the double bonds are converted to polyol. The unsaturated fatty acid
content is quantified by the iodine value as the double bonds adsorb iodine to form
saturated compounds. The amount of iodine adsorbed indicates the number of
double bonds hence unsaturated fatty acid concentration in the oil. In broad
chemical terms, iodine value can be defined as the amount of iodine (grams)
adsorbed by 100 grams of oil or fat (Ketaren, 2005). Potential vegetable oils for use
as raw material to produce polyol must posses an iodine value in the range of 80 to
240 gram I2/100 gram oil to be economic. Vegetable oils with lower iodine values
will produce polyol with a very low hydroxyl value. Therefore, the iodine value of
feedstock is the key determinant of suitability for polyol synthesis (Petrovic et al.,
2003). RBO is a potentially attractive feedstock that can be used as a raw material
for polyol production because it has high content (about 74%) of unsaturated fatty
acids (oleic and linoleic acid) and an iodine value of 99.9 gram I2/ 100 gram oil.
The composition, physical and chemical characteristics of RBO are primarily
determined by soil conditions in the growing area. For example, the iodine value of
RBO produced from a rice plant in Texas was 102.3 gram I2/100 gram oil, whereas
RBO extracted in North America States has an iodine value 99.9 gram I2/100 gram
oil. Table 2.1 provides a typical chemical composition of RBO measured by
Jamieson (in Bailey, 1951) whereas Table 2.2 provides the physical and chemical
characteristic of RBO. Both tables are derived from rice cultivated in the Northern
US (Bailey, 1951). Saponification value indicates the amount of potassium
hydroxide (milligrams) required to saponify 1 gram oil or fat (Ketaren, 2005). In
addition, acid value shows the amount of potassium hydroxide (milligrams) required
to neutralize free fatty acid in 1 gram oil or fat (Ketaren, 2005).

22. 6
Table 2-1 Typical fatty acid composition (wt %) of RBO (Bailey, 1951)
Saturated fatty acid Composition
Myrictic acid (C14H28O2) 0.5 %
Palmitic acid (C16H32O2) 11.7 %
Stearic acid (C18H36O2) 1.7 %
Arachidic acid (C20H40O2) 0.5 %
Lignoceric acid (C24H48O2) 0.4 %
Unsaturated fatty acid Composition
Oleic acid (C18H34O2) 39.2 %
Linoleic acid (C18H32O2) 35.1 %
Unsaponifiable matter 4.64%
Table 2.2 Physical and chemical characteristics of RBO (Bailey, 1951)
Parameters Values
Iodine value 99.9 g I2/100 g oil
Saponification value 185.3 mg KOH/g oil
Acid value 73.7 mg KOH/ g oil
2.2 Epoxidation Reaction
The use of modified plant oils as a renewable feedstock in the chemical industry has
become more desirable. In particular, epoxidized fatty acid derivatives derived from
vegetable oil sources may be utilized as stabilizers and plasticizers in polymers, as
lubricant additives and as an intermediate product in the synthesis of polyol as
constituents of urethane foam. The utilization of epoxidized oil has become more
common over the past few years as such epoxidized oil derived from vegetable oils
is environmentally friendly (Wu et al., 2000). Moreover, plasticizers and additives
for polymer PVC derived from vegetable oil-based have been shown to have
improved performance in terms of high resistance to heat and light (Gan et al.,
1995).

23. 7
epoxidation
The term epoxidized oil is generally understood to denote an oil that is derived from
vegetable oils using the epoxidation reaction. Epoxidized oil contains epoxide
groups or oxirane rings. The term epoxide may be defined as cyclic ethers which
consist of three elements in the epoxide ring. The term oxirane is also usually used
to refer to epoxide according to categorization by IUPAC (Solomons, 1992). The
chemical structure of epoxide according to Solomons (1992) can be illustrated as
follows:
C C
O
Figure 2-2 An epoxide
The general process for synthesis of epoxide groups is known as an epoxidation
reaction wherein an alkene is reacted with an organic peroxy acid. The term peracid
is frequently used and refers to a peroxy acid. The simplified epoxidation reaction is
summarized as follows (Figure 2-3):
O O
R1CH = CHR2 + R’COOH R1HC CHR2 + R’COH
O
Alkene Peroxy acid Epoxide
(or oxirane)
Figure 2-3 Epoxidation reaction
The epoxidation reaction is an important step in the synthesis of polyol. It plays a
key role in contributing to the final hydroxyl groups because epoxide groups will be
converted to hydroxyl groups. A number of studies have shown that a variety of
vegetable oils such as linseed oil, rubber seed oil, mahua oil, karanja oil, soybean
oil, canola oil, cottonseed oil, sunflower oil, corn oil, jatropha oil and methyl esters
of parkia biglobosa seed oil can be used in the epoxidation reaction to produce
epoxidized oils (Chen et al., 2002, Okieimen et al., 2002; Petrovic et al., 2002; Goud
et al., 2006 and 2007; Ikhuoria et al., 2007; Dinda et al., 2007; Benaniba et al., 2007;
Cai et al., 2008; Mungroo et al., 2008). This is due to their high percentage of

24. 8
unsaturated bonds (indicated by high iodine values). For example, soybean oil has
the iodine value of 125 g I2/100 g oil while mahua oil with the iodine value 88 g
I2/100 g oil. In these studies, various factors influencing the kinetics of the
epoxidation step were investigated and are discussed below.
In Okieimen et al’s study (2002), epoxidation reaction by utilizing rubber seed oil as
a raw material to produce epoxidized rubber seed oil was investigated. The influence
of mole ratio of acetic acid and hydrogen peroxide to the oil and the temperature
versus the percentage oxirane oxygen content of epoxidized oil during the
epoxidation reaction were discussed. They concluded that the concentrations of
acetic acid as an oxygen carrier and hydrogen peroxide as an oxidizing agent have a
positive effect in term of increasing the formation of epoxide groups. It was also
reported that the ring opening of oxirane groups could be minimized when the
reaction was carried out at an intermediate temperature range (50 – 60o
C). One of
the limitations of this paper is that it did not discuss the mole ratio of unsaturated
bonds in the oil to hydrogen peroxide or acetic acid.
A study of the epoxidation of soybean oil was conducted by Petrovic et al. (2002).
Their results indicated that at higher temperature (80o
C), acetic acid is more
effective as an oxygen carrier than formic acid to attain high oxirane oxygen
content, whereas formic acid was more effective than acetic acid if the epoxidation
reaction was performed at 40 and 60o
C. In this study, Petrovic et al. (2002) also
investigated the reaction kinetics for epoxidation by determining the rate constant
and activation energy.
An investigation of the epoxidation reaction of mahua oil using hydrogen peroxide
was performed by Goud et al. (2006). They studied the influence of various factors
including catalyst type, temperature, molar ratio of reactant and mixing speed on the
epoxidation reaction. They concluded sulfuric acid is the best catalyst for the
epoxidation reaction producing a high conversion of double bonds to oxirane groups
when the epoxidation reaction was performed at an intermediate temperature of 55-
65o
C to reduce the hydrolysis reaction. In this work, they reported that the economic
value of mahua oil could be increased by converting the oil to an epoxidized mahua
oil.

25. 9
In 2006, Goud et al. investigated the possible use of karanja oil as a feedstock to
produce epoxidized oil. They found that at intermediate temperature in the range of
55 to 65o
C the conversion of double bonds to oxirane groups was optimal and the
reaction time was minimized. It was further also reported that a molar ratio of acetic
acid to karanja oil is 0.5 mole and a mole ratio of 1.5 for hydrogen peroxide to oil
was the optimal concentration for epoxidation of karanja oil. However, this study
would have been much more interesting had the authors included the steps in
determining the reaction kinetics.
A previous study by Purwanto et al. (2006) reported that at temperatures of 60o
C
and higher, the hydroxyl value of the polyol product decreased with reaction time.
Hence, a temperature of 60o
C and 4 h reaction time is the optimal condition for
epoxidation of soybean oil as it has produced polyol with highest content of
hydroxyl value of 151.1 mg KOH/g oil. In addition, this research results in polyol
viscosities in the range of 59.3 to 78.0 centipoises.
Dinda et al. (2008) recently synthesized epoxidized oil from cottonseed oil using
hydrogen peroxide and inorganic acids as a catalyst. These workers reported that the
optimal operating conditions were achieved if the epoxidation reaction was
performed using H2SO4 (best catalyst) at a concentration approximately 2% by
weight, using a mole ratio of hydrogen peroxide to oil in the range 1.5 – 2.0, a mole
ratio of acetic acid as an oxygen carrier to oil of 0.5 at temperatures in the range of
50 – 60o
C. Using these conditions, a high content of oxirane groups was achieved
and degradation of oxirane ring was minimized.
2.3 Hydroxylation Reaction
Throughout this research report, the term hydroxylation reaction is used to refer to
the process of introducing hydroxyl groups into unsaturated bonds to the oil. There
are various sources of hydroxyl groups that can be used in the hydroxylation process
such as alcohols and water. Before the hydroxylation reaction occurs, the oxirane
ring must be opened. There are two ways to open an oxirane ring to permit the

26. 10
+H+
-H+
H-O-H
+
-H++
ROH
hydroxylation reaction to occur. Firstly, ring opening using acid catalyst is
performed (Solomon, 1992). The mechanism of this process can be described as:
C C C C
O O
H
HO C C O H HO C C OH
H
Figure 2-4 Ring opening mechanism using acid catalyst
Another pathway to open oxirane ring uses a base catalyst (Solomon, 1992). The
mechanism of this process is as follows:
RO:- + C C RO C C O- RO C C OH + RO:-
O
Figure 2-5 Ring opening mechanism using base catalyst
A number of studies have found that the hydroxylation reaction is a crucial step in
the synthesis of polyol since it also contributes to the hydroxyl value of polyol by
introducing hydroxyl groups into the oxirane groups (Petrovic et al., 2003;
Setyopratomo et al., 2006; Guo et al., 2006; Lin et al., 2008). They investigated
various epoxidized vegetable oils as raw materials to produce polyols such as
epoxidized soybean oil, safflower oil, sunflower oil, canola oil, corn oil, olive oil
and peanut oil. A variety of factors that may influence in the hydroxylation were
also studied for process optimization.
Extensive work on the hydroxylation of epoxidized oil was undertaken by Petrovic
et al. (2003). In this study, they found that the ratio of alcohol and water to vegetable
oils in the mixture of alcohol and water is important for success in the hydroxylation
reaction. Groups of alcohol that can be used for hydroxylation reaction include
methanol, ethanol, n-propanol, isopropanol and n-butanol. The study would have

27. 11
been more convincing if they had included the influence of temperature and reaction
time on the quality of polyol product.
Kinetic studies of oxirane degradation using methanol have been investigated by Lin
et al. (2008). They were able to produce polyol by reacting epoxidized soybean oil
and methanol without any catalyst in the mixture. The result indicated that
hydroxylation of epoxidized soybean oil was first and second order to the
concentration of epoxidized oil and methanol concentration, respectively. It is
envisaged that the hydroxylation reaction would have been faster had they used
catalyst to open the oxirane ring by using either an acid or base catalyst.
The comparison of performance of acid and base catalysts that influence the
hydroxyl value of polyol products has been investigated for the hydroxylation of
palm oil (Setyopratomo et al., 2006). An acid catalyst represented by H2SO4 shows
better performance than a base catalyst represented by NaOCH3 indicated by a
higher content of hydroxyl groups. The optimal operating condition using acid
catalyst was achieved at temperature of 50o
C and 2 h reaction time.
2.4 Synthesis of Polyol
From the previous section, it is clear that polyol can be synthesized from vegetable
oils that contain unsaturated bonds through two consecutive steps involving
epoxidation and then hydroxylation reactions. In the epoxidation step, the reaction
mechanism can be described as follows (Okieimen et al., 2002):
1. Formation of peroxyacid:
RCOOH + H2O2 RCOOOH + H2O
2. Epoxidation reaction:
R1CH=CHR2 + RCOOOH R1CH CHR2 + RCOOH
O
Figure 2-6 Epoxidation reaction mechanism

28. 12
In the hydroxylation step, the reaction mechanism can be depicted below (Purwanto
et al., 2006):
1. Reaction of epoxidized oil with water:
R1CHOCHR2 + H2O R1-CH-CHR2
OH OH
2. Reaction of epoxidized oil with alcohol:
R1CHOCHR2 + R3OH R1-CH-CHR2
R3O OH
Figure 2-7 Hydroxylation reaction mechanism
A variety of research studies have been undertaken using various raw materials to
synthesize polyol. So far, however, there has been little discussion about the
synthesis of polyol from rice bran oil (RBO). In fact, RBO is a cheap and readily
available by product and waste in the milling rice process which has high content of
unsaturated bonds. Thus, it is our belief that the synthesis of polyol from RBO needs
to be explored.
2.5 Response Surface Methodology
Response surface methodology (RSM) is method for performing process
optimization using mathematics and statistics to construct a model of the process to
determine the optimal process conditions (Myers, et al., 1995; Montgomery, 2005).
The relationship between independent variables (x) and dependent (response)
variables (y) is usually unknown and complex and RSM is applied to determine an
estimation equation that represents closely the relationship between x and response
variables (y). For ease of application, a low-order polynomial model is normally
employed to represent estimation function. The first order model is the simplest
model employed (Equation 2-1):
εββββ +++++= kk xxxy ...22110 (2-1)
or second order model (Equation 2-2):
εββββ ∑ ∑∑∑ ==
++++=
k
i
jiijiii
k
i
ii xxxxy
1
2
1
0 (2-2)

29. 13
The next step is to perform an experimental design and then this step is followed by
data analysis. The actual values of variables are normally expressed in coded values
for analysis. The coded value is given by equation (2-3):
i
i
i
x
xx
X
∆
−
= 0
(2-3)
Where: iX = the coded value of an independent variable
ix = the real value of an independent variable
0x = the real value of an independent variable at the centre point
ix∆ = the value of step change
Following this, the range and level of variables is determined to indicate scope of
variables includes the experimental design to determine the model parameters. The
fitted surface is then employed to analyze the response surface. If the resulting
response surface is statistically a good fit then the response surface will be a close
approximation of the real system.
Application of RSM for process optimization is a commonly used strategy. The
developed model can be easily maximized or minimized to determine the best
response variables. Thus in process optimization of a particular chemical process,
RSM can determine the optimal operating condition and offer benefits such as
reduced experimental time, a less complexity, and highly efficient process.
2.6 Key Research Question
Over the last a few decades, polyol derived from petroleum oil as feedstock has been
used to produce polyurethane to fulfill the world’s needs for this polymer. Recently,
a number of studies have been conducted to investigate the use of vegetable oils as a
renewable and sustainable feedstock to replace the use of petroleum oil. Many
researchers have concluded that vegetable oil can be exploited as an alternative raw
material to substitute for petroleum oil to produce polyol. Examples include soybean
oil, safflower oil, olive oil, canola oil, cottonseed oil, palm oil and rapeseed oil
(Petrovic et al., 2003). Vegetable oil – based polyol is a sustainable material which

30. 14
can be efficiently produced through two-consecutive steps, epoxidation and
hydroxylation reactions. Rice bran oil is a potential feedstock source.
The unsaturated fatty acid content in RBO is indicated by its iodine value. RBO with
an iodine value of 99.9 g I2/100 g oil has 74.3% of total unsaturated fatty acid (oleic
and linoleic acid) in the oil (Bailey, 1951). A key criterion to economically produce
polyol is to use vegetable oil with an iodine value in the range of 80 to 240 to
accomplish high hydroxyl value and consequently allow production high viscosity
of polyol product (Petrovic et al., 2003). To date, the normal route to produce polyol
is by converting unsaturated bonds in the oil in a two step process using epoxidation
followed by hydroxylation reactions.
Research conducted by Purwanto et al. (2006) and Lin et al. (2008) has shown that
the epoxidation and hydroxylation reactions contribute to hydroxyl value of the final
product of polyol. In the epoxidation step, unsaturated bonds in RBO are converted
to produce epoxy groups indicated by the percentage of oxygen content. A high
percentage of oxygen content in the epoxidized oil has more epoxy groups.
Therefore, this research investigated the influence of the reaction time, reaction
temperature and type of peroxy acid (peroxyacetic acid and peroxyformic acid) as
oxygen carrier in order to determine the optimal operation conditions in the
epoxidation reaction.
In the hydroxylation step, the epoxy groups in the epoxidized oil are converted to
form hydroxyl groups called polyol. A good quality of polyol is indicated by a high
hydroxyl value. Therefore, intensive research needs to be conducted to investigate
key process variable in the hydroxylation step that influence the final quality of the
product of polyol. In other words, the optimum operating conditions in the
hydroxylation step also need to be quantified, such as reaction time and temperature
to attain high quality of polyol products synthesized from rice bran oil.

31. 15
2.7 Research Objectives
This study is divided into two steps. The first step deals with the determination of
optimal operating conditions in the epoxidation step in terms of reaction time and
temperature. The aims of the first step in this study are:
• to investigate the optimal operating condition in the epoxidation step using
acetic acid and formic acid as oxygen carriers (peroxyacetic and
peroxyformic acid respectively) to attain epoxidized oil with high oxygen
content.
• to determine the reaction kinetics in the epoxidation step using formic acid as
an oxygen carrier (peroxyformic acid).
• to compare the performance of acetic acid and formic acid as oxygen carriers
in the epoxidation step in converting double bonds to epoxy groups.
The optimum operating conditions obtained in the epoxidation step will be used to
generate epoxidized oil samples for the next step.
The second stage of this research considers the determination of the optimal
operating conditions in the hydroxylation step for the synthesis of polyol. The aim of
the second step in this study is to investigate the optimal reaction time and
temperature in the hydroxylation step to attain polyol of high quality indicated by a
high content of hydroxyl value with a reasonable viscosity. At present there is no
fixed specification for polyol viscosity.
2.8 Significant/Contribution to the Discipline
Vegetable oil particularly rice bran oil (RBO) is an alternative raw material to
produce polyol for the next generation. This is important since it can lessen the
world’s reliance on petroleum oil and the limited amount of non-renewable
resources can be saved as a heritage for future generations. Polyol derived from
vegetable oil could overcome the problem in the application of polyol derived from
petroleum since polypropylene oxide (PPO) triols derived from petroleum oil tend to
undergo oxidation processes, thus these materials are rather unstable. By contrast,
polyol from vegetable oils are resistant to oxidative degradation. Other benefits of

32. 16
polyurethanes produced from vegetable oil based-polyol are stability under thermal
stress and improved dielectric properties (Guo et al., 2000).
Over the past few decades, the world’s demand for polyurethanes has increased and
these polyurethane compounds can also be produced from vegetable oils (John et al.,
2002). Therefore, the use of RBO in particular, could increase the economic value of
RBO. Furthermore, the availability of RBO as a raw material can be guaranteed
since RBO-oil is a renewable resource. A high content of unsaturated bonds
indicated by high iodine value of RBO allows high yield of hydroxyl groups, a key
requirement for economic production of RBO based polyols.
Epoxidation and hydroxylation reactions are crucial steps to produce a high quality
of polyol as indicated by a high hydroxyl value with reasonable viscosities. The
synthesis of polyol with the utilization of soybean oil, corn oil, safflower oil,
sunflower oil, canola oil, olive oil and peanut oil has been studied extensively by
Petrovic, Guo, and Javni (2003). However, there is significant lack of information
on the use of RBO as a starting material to produce polyol. As the epoxidation and
hydroxylation steps also contribute to the final product of polyol, the optimum
operating conditions for reaction time and temperature in the epoxidation and
hydroxylation reactions must be determined. The best form of peroxy acid as
oxygen carrier (peroxyacetic acid or peroxyformic acid) in the epoxidation step must
also be investigated to determine the key parameters hydroxyl value and the
viscosity of polyol product. High grade polyols will have a high hydroxyl value with
reasonable viscosity.
Determination of the optimum operating conditions for polyol production in the
epoxidation and hydroxylation stages will result in a cheap, more efficient process.
Both reaction time and temperature have a close relationship with energy
consumption in the process hence, optimum reaction time and temperature could
prevent energy waste so that an efficient process could be attained. This could
produce many benefits such as reducing production cost and maximizing selection
process.

33. 17
In addition, if we can use RBO as a raw material to produce polyol, it can save
petroleum as a non-renewable resource. This research can also support the
establishment of vegetable oil–based polyol industries. Hence, it will automatically
create more work opportunities and also contribute largely to the national economy.
Furthermore, this research can encourage and support other research to use
renewable natural resources. Therefore, this research generally can encourage the
creation of renewable natural resources-based industry.

34. 18
3 MATERIALS and METHODS
The purpose of this research is as an initial study of the synthesis of polyol from rice
bran oil to increase its added value and to determine the optimal reaction conditions.
The two consecutive steps for the synthesis of polyol are epoxidation and
hydroxylation reactions. These reactions were investigated to determine the optimal
operating conditions in the epoxidation reaction using acetic acid and formic acid
where the oxygen carriers and the reaction kinetics using formic acid in the
epoxidation step and hydroxylation reaction are subjects of evaluation. Formic acid
was selected to study the reaction kinetics in the epoxidation step as the formation
rate of peroxyformic acid is faster than peroxyacetic acid (Kirk-Othmer
Encyclopedia of Chemical Technology, 1965). This chapter outlines the research
methods applied in this investigation.
3.1 Materials
The raw materials for this study of the epoxidation reaction were rice bran oil (Old
Fashioned Foods Ltd) which was purchased from a supermarket; glacial acetic acid
(Chem Supply); formic acid (Chem Supply); hydrogen peroxide 30 wt% (Ajax
Finechem); sulfuric acid 95 – 98 wt% (Ajax Finechem). Furthermore, methanol
(Chem Supply); isopropanol (Chem Supply); sulfuric acid 95 – 98 wt% (Ajax
Finechem); and water were used in the hydroxylation reaction.
3.2 Epoxidation Reaction
The epoxidation reaction was carried out in a 500 mL three neck flask batch reactor,
equipped with agitator, reflux condenser and thermocouple. The three neck flask
was immersed in a heating mantle whose temperature could be controlled to less
than ±2 K. A schematic of the experimental apparatus for the epoxidation reaction is
illustrated in Figure 3-1.

35. 19
Notes:
A. Three neck flask
B. Mechanical stirrer
C. Condenser
D. Heating mantle
E. Retort and stand
F. Thermocouple
Figure 3-1 Experimental apparatus of epoxidation reaction
In order to meet the research objectives for the epoxidation step, two initial studies
were performed. The first study determined the optimal operating condition for the
epoxidation reaction as a function of reaction time and temperature using acetic acid
as the oxygen carrier (peroxyacetic acid). A response surface methodology (RSM)
was then performed to obtain the optimal operating condition for this epoxidation
reaction using peroxyacetic acid. The second study focused on determining the
optimal operating condition using formic acid as the oxygen carrier (peroxyformic
acid) and investigated the reaction kinetics. The optimal condition obtained from
epoxidation step in terms of oxygen carrier, reaction time and temperature was used
for the next step in the synthesis of polyols from RBO through epoxidation and
hydroxylation reactions.
Prior to the epoxidation reaction, RBO was analyzed to determine its initial iodine
value. The RBO was then used as the feedstock for the epoxidation stage. The
experimental method for the epoxidation step (adapted from Goud et al., 2007) is as
follows: rice bran oil (RBO) in the amount of 200 mL was placed in the 500 mL
three neck flask equipped with reflux condenser. Formic acid or acetic acid at a
molar ratio of 0.5:1 to the oil and sulfuric acid catalyst 3% weight of hydrogen
peroxide and oxygen carrier was added into RBO. A hydrogen peroxide molar ratio

36. 20
of 1.5:1 to the oil was then added drop-wise into the mixture. This feeding strategy
was required to avoid overheating the system as the epoxidation reaction is highly
exothermic. The reaction was well mixed and was performed at a stirring speed of
1600 rpm under isothermal conditions at several temperatures and reaction times.
The product of the reaction was next cooled and decanted to effect a separation of
the organic-soluble compounds (epoxidized oil) from water-soluble phase. The
epoxidized oil was then washed with warm water (in small aliquots) to remove
residual contaminants. The product was then analyzed to determine its iodine value
and oxirane content.
3.3 Hydroxylation Reaction
The hydroxylation reaction was performed in a 1000 mL glass reactor, equipped
with stirrer, reflux condenser and thermocouple. The reactor was placed on a heating
plate with temperature control. A photograph of the experimental apparatus for
hydroxylation reaction is presented as Figure 3-2.
Figure 3-2 Experimental apparatus of hydroxylation reaction

37. 21
As noted earlier in order to determine the optimal operating condition for the
hydroxylation step, the optimal condition obtained from epoxidation reaction was
applied to produce the epoxidized oil feedstock. Therefore, epoxidation reaction at
the optimal operating condition was followed by hydroxylation reaction. To meet
the research objectives of determining the overall optimal process conditions, the
optimal operating parameters for the hydroxylation reaction were investigated in
terms of reaction time and temperature. Then RSM was performed to deduce the
optimal operating condition in the hydroxylation reaction.
The procedure for hydroxylation reaction (adapted from Petrovic et al., 2003) is as
follows: 150 mL epoxidized oil was hydroxilated using a mixture of alcohols
(methanol and isopropanol), water and sulfuric acid as a catalyst. Mixture of alcohol
(methanol and isopropanol) with molar ratio of 4:1 to the oil each and water at molar
ratio of 2:1 were mixed with the epoxidized RBO and sulfuric acid catalyst in the
reactor. The reaction was performed at several fixed temperatures and reaction
times. The reaction product (polyol) was then washed with warm water (in small
aliquots) to remove contaminants and then decanted to effect a separation of the
organic-soluble compounds (polyol) from water-soluble ones. The resulting polyol
produced from the hydroxylation process was then analyzed using two key
parameters: the hydroxyl value and the viscosity of the product polyol. Again RSM
was performed to determine the optimal operating conditions for the hydroxylation
process.
3.4 Epoxidation Test
This section summaries the analysis methods used to evaluate yield from the
epoxidation reaction evaluation in terms of the two key variables, namely iodine
value and oxirane oxygen content.
3.4.1 Iodine Value Analysis
Iodine value was determined by applying the Wijs method (Ketaren, 2005; Siggia,
1963; Sudarmaji et al., 1997). The sequence of the procedure is as follows: 0.1 to 0.5

38. 22
grams of sample were placed into the flask. 10 mL of chloroform was then added to
the sample. Following this, 15 mL Wijs iodine solution was added. Using the same
procedure, blank solution was also prepared. The mixture was then stored in a dark
place for at least 30 minutes at temperature of 25±5o
C and after that, 10 mL of 15
wt% potassium iodide (KI) solution and 50 mL of water were added into the
mixture. The iodine content in the mixture was then titrated using 0.1 N sodium
thiosulfate solution until the yellow colour of the solution almost disappeared. A few
drops of starch indicator solution were then added and titration was continued until
the blue color completely disappeared. The iodine value was calculated using the
following equation:
Iodine value
( ) ( )
C
xNxAB 69.12−
= (3-1)
Where:A = Volume of Na2S2O3 solution required for titration of the sample (mL).
B = Volume of Na2S2O3 solution required for titration of the blank solution
(mL).
C = weight of sample (gram).
N = normality of Na2S2O3 solution.
3.4.2 Oxirane Oxygen Content Analysis
The oxirane content of the epoxidized oil must be quantified to determine the
conversion of unsaturated bonds in RBO to oxirane groups. The procedure (adapted
from Siggia, 1963) is as follows: a calculated amount of epoxidized oil was added
into a flask. 5 mL of ethyl ether was used to wash the flask side and then 10 mL of
the hydrochlorination reagent (0.2 N HCl in ethyl ether) was added into the flask.
Simultaneously, a blank solution was prepared using an identical procedure. The
mixture was then allowed to stand for 3 hours at room temperature. The mixture was
then titrated with standard 0.1 N sodium hydroxide solution. Prior to this, a few
drops of phenolphthalein indicator solution and 5 0mL of ethanol solution were
added. The percentage of oxirane content was calculated using the following
equation:

39. 23
% oxirane oxygen content
( )
1000
10016
xW
xxNxVV sb −
= (3-2)
Where: bV = volume of NaOH used for blank (mL).
sV = volume of NaOH used for sample (mL).
N = normality of NaOH
W = weight of the sample (gram)
3.5 Hydroxylation Test
This section summaries the analysis techniques and methodology used for
evaluation of the hydroxylation step evaluation in terms of hydroxyl value and
viscosity.
3.5.1 Hydroxyl Value Analysis
The hydroxyl content of hydroxilated oil (polyol) must be determined as the
hydroxyl value of RBO based-polyol is a key measure of the quality of the resultant
polyol product. The procedure was adapted from the work of Ketaren (2005). Prior
to this, the saponification value of the sample must be determined before and after
the acetylation process. In the acetylation process, the hydroxyl groups in the oil are
converted to ester then analyzed in terms of their saponification value before and
after the acetylation process to determine the amount of hydroxyl groups.
In the acetylation process, 20 mL of oil sample was mixed with 20 mL of acetic
anhydride in a flask. The mixture was then boiled for 2 hours. Following this, 50 mL
of water was added into the mixture and the mixture was boiled for 15 minutes. It
was then cooled and washes water then used to effect a separation from the mixture.
After that, 50 mL of water was added and mixture was boiled for 15 minutes. This
procedure was repeated several times until the washing water was neutral. After the
washing water was separated, acetylated oil was dried over sodium sulfate
anhydrous and then filtered.

40. 24
In the saponification process, a calculated amount of oil was placed into a flask. 20
mL of alcoholic potassium hydroxide (0.5 N) was then added into the flask and the
mixture was boiled to form saponificable oil. The mixture was then cooled and the
flask side was washed with little water. After that, a few drops of phenolphthalein
indicator were added and the mixture was then titrated with 0.5 N hydrochloric acid
solution until the red color entirely disappeared. Using the same procedure, a blank
solution was prepared and then titrated with hydrochloric acid solution. The
hydroxyl value of polyol was calculated using the following equation:
Saponification value
( )
G
xBA 05.28−
= (3-3)
Where: A = milliliters of 0.5N HCl required for blank solution.
B = milliliters of 0.5N HCl required for sample.
G = weight of the sample (g).
05.28 = a half value of molecular weight of KOH
Hydroxyl value
( )SA
SBSA
00075.01−
−
= (3-4)
Where: SA = saponification value after acetylation process
SB = saponification value before acetylation process
3.5.2 Viscosity Analysis
The viscosity of RBO based-polyol were measured at 25o
C using Brookfield
viscometer VT 550 connected to computer software. The procedure is as follows:
the computer connected to viscometer apparatus was turned on. Prior to turning on
the viscometer apparatus, the “job manager” in the computer program was opened.
After that, the polyol samples were filled in into the cup. Following this, the cup was
inserted into temperature control vessel and secured by screwing at the bottom. In
order to control temperature at 25o
C, a water bath equipped with controller with a
fixed set point temperature in the water bath. Once the file job was opened on the
computer, the speed level was selected and then rotor started to rotate. The collected
data was checked in data manager and then changed into shear stress )(τ and shear
rate )(
•
γ . The viscosity was measured as the ratio of shear stress and shear rate.

41. 25
4 EXPERIMENTAL RESULTS and DISCUSSION
This section summarizes the results obtained from the experiments performed in the
laboratory. Specifically, it will discuss critically the synthesis of polyol from RBO
through epoxidation and hydroxylation steps. Hence, it is divided into three sections
consisting of epoxidation using acetic acid and formic acid as oxygen carriers
followed by hydroxylation of epoxidized oil to determine the optimal operating
conditions for the two stage involved in the synthesis of polyol from RBO.
4.1 Epoxidation of RBO - Acetic Acid as an Oxygen Carrier
(1st
Study)
During the epoxidation reaction, double bonds in the oil are converted to oxirane
rings. Hence, the objective function for determining the optimal condition in the
epoxidation reaction using acetic acid as an oxygen carrier is to maximize the
amount of oxirane groups as indicated by a high amount of oxirane oxygen content.
Response surface methodology (RSM) provides an efficient experimental strategy to
study the influence of imposed variables to discover a final optimum condition
(Montgomery 2005, p. 405). Furthermore, RSM has additional benefits such as it
allows determination of interaction effects between variables (Wang et al., 2008)
and saves time as a reduced number of experiments are required (Doddapaneni et
al., 2007).
4.1.1 Experimental Design and Optimization of the Epoxidation
Reaction
Full factorial central composite design (CCD) was employed and the total number of
treatment combinations can be represented as 022 nkk
++ (Doddapaneni et al.,
2007).
Where: k
2 = factorial design
k2 = star point
k = the number of independent variables

42. 26
0n = the number of replications at the centre point
This first study evaluated the effect of two independent variables (reaction time and
temperature) of epoxidation reaction on the response variables (% conversion and %
oxirane content). The central values of the independent variables in the epoxidation
of RBO using acetic acid as an oxygen carrier were a batch reaction time of 4 hours
at a temperature of 60o
C. The two independent variables to be optimized were coded
1X and 2X at five levels (-2, -1, 0, 1, 2) using the equation below:
i
i
i
x
xx
X
∆
−
= 0
(4-1)
Where: iX = the coded value of an independent variable
ix = the real value of an independent variable
0x = the real value of an independent variable at the centre point
ix∆ = the value of step change
The distribution of coded 1X and 2X at five levels is indicated in Table 4-1. At this
stage, 4 points factorial design, 4 star points and 3 replicates at the central points (all
factors at level 0) were performed to fit with the second order polynomial model.
Hence, 11 experiments were conducted for the epoxidation of RBO using acetic acid
as an oxygen carrier.
Table 4-1 The range and levels of variables used in the RSM procedure to determine
the optimum conditions for the epoxidation reaction of RBO
Variables Symbol coded Range and levels
-2 -1 0 1 2
Reaction times (h)
Temperatures (o
C)
1X
2X
2 3 4 5 6
40 50 60 70 80

43. 27
4.1.2 Statistical Analysis
A second-order polynomial model (Equation 4-2) was fitted to represent the
experimental data presented in Table 4-2.
2112
2
222
2
11122110 XXXXXXY ββββββ +++++= (4-2)
Where )21( −=iYi is the response ( 1Y = % conversion and 2Y = % oxirane content);
0β is a constant; 1β and 2β represent the linear coefficients; whilst 11β and 22β are
the quadratic coefficients; 12β is the interaction coefficient.
Table 4-2 CCD and response in terms of conversion and oxirane content during the
epoxidation of RBO
Reaction time
(h)
Temperature
(o
C)
Conversion
(%)
Oxirane
(%)
Exp. No.
1X 2X 1Y 2Y
1 -1 -1 50.5 1.69
2 1 -1 67.7 2.16
3 -1 1 67.7 2.48
4 1 1 81.4 2.32
5 -2 0 42.7 1.76
6 2 0 78.6 2.40
7 0 -2 23.7 1.65
8 0 2 88.0 2.20
9 0 0 67.7 2.61
10 0 0 65.2 2.62
11 0 0 65.5 2.58
Microsoft Excel was used to analyze the results in the form of an analysis of
variance (ANOVA).
For each reaction time and corresponding temperature, the conversion ( )1Y and
oxirane content( )2Y were determined for the epoxidation process. The correlation of
the responses 1Y and 2Y to the coded values of variables was estimated using

44. 28
multiple linear regression. The obtained regression coefficients are presented in
Table 4-3 and the analysis of variance (ANOVA) is provided as Table 4-4. Analysis
of regression statistics from the analysis of variance indicated a good fit and
reasonable significance F < 0.01.
Table 4-3 Regression statistics for conversion and oxirane content for epoxidation
of RBO
Regression statistics Conversion ( )1Y Oxirane content ( )2Y
Multiple R
R Square
Adjusted R Square
Standard Error
Observations
0.963
0.927
0.854
7.033
11
0.965
0.931
0.861
0.138
11
Table 4-4 Analysis of variance (ANOVA) for conversion and oxirane content for
epoxidation of RBO
Source DF SS MS F Significance F
Conversion
Oxirane
content
Regression
Residual
Total
Regression
Residual
Total
5
5
10
5
5
10
3146.0
247.3
3393.3
1.273
0.095
1.37
629.2
49.5
0.254
0.019
12.72
13.40
0.0072
0.0064

45. 29
Table 4-5 Significance of regression coefficients for conversion of epoxidation of
RBO
Coefficients Standard Error t Statistic P-value
Intercept 68.079 3.608 18.870 7.7E-06a
1X 8.554 2.030 4.213 0.0084b
2X 13.294 2.030 6.548 0.0012b
2
1X -1.490 1.601 -0.931 0.3947
2
2X -2.694 1.601 -1.683 0.1532
21 XX -0.887 3.517 -0.252 0.8109
a
Significant at 0.1% (p<0.001)
b
Significant at 1.0% (p<0.01)
Table 4-6 Significance of regression coefficients for oxirane content of epoxidation
reaction
Coefficients Standard Error t Statistic P-value
Intercept 2.543 0.0707 35.961 3.13E-07a
1X 0.132 0.0398 3.324 0.0209c
2X 0.170 0.0398 4.271 0.0079b
2
1X -0.127 0.0313 -4.043 0.0099b
2
2X -0.165 0.0314 -5.264 0.0033b
21 XX -0.161 0.0689 -2.336 0.0667
a
Significant at 0.1% (p<0.001)
b
Significant at 1.0% (p<0.01)
c
Significant at 5.0% (p<0.05)
The model is a good fit of the experimental data as indicated by high values of the
correlation coefficients (R2
) for the responses. The data analysis for regression was
undertaken using Microsoft Excel whereas Matlab plotting software was employed
to visualize the results.

46. 30
4.1.3 Effects of Reaction Time and Temperature on Reaction
Conversion
The experimental data from the central composite design was fitted with a second-
order polynomial model by performing multiple linear regressions. The correlation
between conversions of iodine value 1Y and the two independent variables (reaction
time and temperature) in coded units after applying of response surface
methodology can be represented by equation:
21
2
2
2
1211 89.069.249.129.1355.808.68 XXXXXXY −−−++= (4-3)
Where 1Y (conversion of iodine value in %) is the response, and 1X and 2X are the
coded values of the independent variables (reaction time and temperature).
Figure 4-1 Effects of reaction time (X1) and temperature (X2) on reaction
conversion for acetic acid as an oxygen carrier
The result indicates that the conversion of iodine value in the RBO increases linearly
with the rise of reaction time and temperature, and at a faster rate with temperature
than with reaction time (Figure 4-1). These effects are positive and significant at p <
0.01 confidence level for both reaction time and temperature (Table 4-5).

47. 31
Unsaturated double bonds present in the oil are converted to oxirane rings through
the epoxidation reaction as indicated by the decrease in the iodine value. This value
in the RBO represents the concentration of double bonds and it decreases with
reaction time (Petrovic et al., 2002). Therefore, the reaction conversion increases
with reaction time and temperature. These findings are also consistent for
epoxidation of cottonseed oil with those Dinda et al. (2008) who also reported a
similar behaviour.
4.1.4 Effect of Reaction Time and Temperature on Oxirane
Content
The empirical relationship between oxirane content and the two independent
variables (reaction time and batch temperature) in coded units is represented as:
21
2
2
2
1212 161.0165.0127.0170.0132.0543.2 XXXXXXY −−−++= (4-4)
The regression result (Table 4-6) shows that oxirane content in the RBO is a
quadratic function of reaction time and temperature. All the observed effects were
significant at p < 0.05 (Table 4-6). As can be seen from Figure 4-2, the amount of
oxirane content increases with reaction time and temperature and then that value
reaches the maximal level. Following this, the oxirane content decreases with
reaction time and temperature.

48. 32
Figure 4-2 Effects of reaction time (X1) and temperature (X2) on oxirane content for
acetic acid as an oxygen carrier
There are two major reactions involved in the epoxidation reaction (Petrovic et al,
2002; Milchert et al., 2009). During the first stage, peroxyacetic acid is formed from
the reaction of acetic acid and hydrogen peroxide as summarized by:
CH3COOH + H2O2 CH3COOOH + H2O (4-5)
During the second stage, epoxidized oil is produced from the reaction between
peroxyacetic acid and double bonds in the oil, illustrated as:
CH3COOOH + CH CH CH CH + CH3COOH (4-6)
O
The maximum oxirane content was achieved at a reaction time (coded) 0.28 and at a
temperature (coded) 0.38 (Appendix C.4). These coded values were attained using
calculation to determine the function’s stationary points by taking partial derivatives
of the polynomial equation of oxirane content. The real values of variables at the

49. 33
optimal condition was deduced by converting these coded values to the original
scale using equation (4-1) and the optimal condition for the epoxidation reaction
occurred with reaction time of 4.3 h at a batch temperature of 63.8o
C. At higher
reaction time and temperature, the reaction results in lower oxirane content. This is a
result of a high temperature of epoxidation reaction favouring a high rate of oxirane
ring opening thereby producing a product with reduced oxirane content (Purwanto et
al., 2006). Therefore, higher side reaction products may be formed above the
optimal temperature such as reaction between oxirane rings and acetic acid or water
and a dimerization reaction may occur (Petrovic et al., 2002; Milchert 2009). These
findings are also consistent with those of Dinda et al. (2008) who found at higher
temperature (60o
C or higher) the relative conversion to oxirane increased to an
optimal operating point and then declined gradually in the epoxidation of cottonseed
oil.
4.2 Epoxidation of RBO – Formic Acid as an Alternate Oxygen
Carrier (2nd
Study)
This section presents results and critical discussions for epoxidation using formic
acid as an oxygen carrier (peroxyformic acid generated in situ). Experiments were
performed to investigate reaction conversion and oxirane content of epoxidized oil.
The results will be utilized to study the influence of reaction time and temperature
on the reaction conversion, kinetics and oxirane content. The purpose is to determine
the optimal operating condition utilizing peroxyformic acid generated in situ and
also to determine if formic acid is better than acetic acid as an oxygen carrier.
4.2.1 Effects of Reaction Time and Temperature on the Conversion
The results of this study indicate the reaction conversion increases with increasing
reaction time and temperature (Figure 4-3). It means that the concentration of double
bonds decreases with increasing reaction time and temperature since double bonds
are represented by the iodine value (Petrovic et al., 2002). This finding supports
previous research with the utilization of cottonseed oil as a raw material to produce
epoxidized oil (Dinda et al., 2008). This result can be explained by the fact that

50. 34
through the epoxidation reaction double bonds in the oil were converted to
epoxidized oil. A model that can illustrate for rate constant increases with
temperature is Arrhenius’ law (Levenspiel, 1972; Fogler, 2006):
RTE
ekk /
0 . −
= (4-7)
Where: 0k = frequency factor
E = activation energy
R = gas constant
T = absolute temperature (in Kelvin)
From Equation (4-7), it is clear that reaction constant ( )k is a function of reaction
temperature( )T . If the reaction temperature goes up, the reaction constant value will
increase. Hence, it will increase the reaction rate of epoxidation and in this case a
higher final conversion resulted.
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
0 1 2 3 4 5 6 7
t (h)
X(%)
40 C 50 C 60C 70 C 80 C
Figure 4-3 Effects of reaction time (t) on reaction conversion (X) for formic acid as
an oxygen carrier at different temperatures

51. 35
4.2.2 Reaction Kinetics
Epoxidation reaction using peroxyformic acid generated in situ was performed with
a high stirring speed at 1600 rpm to avoid mass transfer resistance and to achieve an
homogenized two phase system. Research that has been conducted by Goud et al.
(2006) confirms that epoxidation of mahua oil is not controlled by mass transfer
resistance if stirring speed exceed 1500 rpm. Therefore, in this research stirring
speed at 1600 rpm was used to ensure that the epoxidation reaction was controlled
by chemical reaction. The experimental results for conversion of iodine value were
employed to determine the reaction kinetics in the epoxidation using peroxyformic
acid in terms of reaction order, rate constant and activation energy.
There are two major reactions involved in the epoxidation reaction (Petrovic et al.
2002). During the first stage, peroxyformic acid is formed from the reaction of
formic acid and hydrogen peroxide as summarized by:
HCOOH + H2O2 HCOOOH + H2O (4-8)
During the second stage, epoxidized oil is produced from the reaction between
peroxyformic acid and double bonds in the oil illustrated as:
HCOOOH + CH CH CH CH + HCOOH (4-9)
O
General form of rate equation for conversion of double bonds by peroxyformic acid
in Equation (4-10) may be written as:
[ ]
[ ] [ ]1 2
3
n nd DB
k DB PFA
dt
− = (4-10)
Where:
[ ]DB = Molar concentration of double bonds
[ ]PFA = Molar concentration of peroxyformic acid
3k = Reaction rate constant
1n = Reaction orders with respect to the double bonds concentration

52. 36
2n = Reaction orders with respect to the peroxyformic acid concentration
If it is assumed that epoxidation is pseudo-first order with respect to the double
bonds, the rate equation for pseudo-first order can be expressed as:
[ ]
[ ]
d DB
k DB
dt
− = (4-11)
Where: [ ] 2
3
n
k k PFA=
Then rate equation data for the epoxidation reaction using peroxyformic acid is
fitted with Equation (4-11). If X is expressed as the conversion of double bonds in
the oil, after integration the equation above can be defined as [ ] [ ] ( )0
1DB DB X= −
and the equation (4-11) can be integrated to give:
tk
X
.
1
1
ln =



−
(4-12)
The rate constant ( )k value for each temperature can be determined as the slope of
the plot of 



− X1
1
ln versus reaction time (t) and the results summarized in Table 4-
7.
Table 4-7 Rate constant value at different temperatures for epoxidation using
formic acid
Temperature (o
C) k value (h-1
) R2
40 0.172 0.9525
50 0.304 0.9423
60 0.374 0.877
70 0.425 0.862
80 0.492 0.8261
The result shows that k value increases with reaction temperatures. The present
findings are consistent with the Arrhenius equation which states that the rate
constant (k) value is dependent on temperature (T). The most interesting finding was
that the rate equation model indicated a good fit as a high significance is indicated
by high value of the correlation coefficient. Hence, it can be concluded that
epoxidation of RBO using formic acid as an oxygen carrier is pseudo-first order

53. 37
with respect to the concentration of double bonds. Another important finding was
that at higher temperature, epoxidation reaction deviates from pseudo-first order
model since the plot of 



− X1
1
ln versus reaction time ( )t become less linear as
indicated by reducing correlation coefficient values as temperature increases (Table
4-7). The experimental data was taken at five different temperatures of 40, 50, 60,
70 and 80o
C. Samples were taken every 1 hour reaction time and maximal 6 hour
reaction time.
The activation energy of epoxidation reaction with the use of peroxyformic acid was
calculated from k values at different temperatures by performing Arrhenius
equation:
RTE
ekk /
0 . −
= (4-13)
RT
E
kk −= 0lnln (4-14)
The activation energy was calculated from the slope plot of kln versus T/1 (Figure
4-4)
Figure 4-4 Determination of activation energy for epoxidation using formic acid
as an oxygen carrier
ln(k)= -2716.2(1/T) + 7.072
R2 = 0.9065
-2
-1.8
-1.6
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.0028 0.0029 0.003 0.0031 0.0032 0.0033
1/T
ln(k)
Experimental values

54. 38
The result indicates the activation energy of epoxidation reaction using
peroxyformic acid is 22.6 kJ/mol. This value of activation energy is lower than the
results of Petrovic et al. (2002) for epoxidation of soybean oil using peroxyformic
acid (E = 35.94 kJ/mol). The lower value for the activation energy of rice bran oil is
probably related to the characteristic of the feed source. Soybean oil has a higher
concentration of double bonds in the oil with an iodine value of 125 gram iodine per
100 gram oil whereas in this research the iodine value of rice bran oil is 98.2 gram
iodine per 100 gram oil.
4.2.3 Effects of Reaction Time and Temperature on Oxirane
Content
In the synthesis of polyol, epoxidation reaction is a key aspect to obtain polyol
products with high hydroxyl value. Hence, the optimal operating condition in the
epoxidation step must be clearly defined to achieve high content of epoxy groups
since it will be used to generate raw material to produce polyol. In the epoxidation
of RBO using formic acid as an oxygen carrier as indicated in Figure 4-5, the
oxirane content of epoxidized oil increases with reaction time at lower temperatures
(40 and 50o
C). From Figure 4-5, it is apparent that at higher temperatures (60, 70
and 80o
C) the oxirane content increases with reaction time then achieves optimal
level before declining. These findings are also consistent with those of Dinda et al.
(2008) who found for epoxidation of cottonseed oil that at higher temperature (60o
C
or higher) the relative conversion to epoxy groups increased to an optimal operating
point and then declined gradually. Maximum oxirane content of 3.26% was
achieved at 4 hours reaction time and temperature of 60o
C. Hence, the results of this
study indicate that the optimal operating condition for epoxidation reaction was
achieved at a reaction time of 4 hours and a temperature of 60o
C.

55. 39
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5 6 7
t (h)
%oxirane 40 C
50 C
60 C
70 C
80 C
Figure 4-5 Effects of reaction time (t) on oxirane content (%) for formic acid as an
oxygen carrier at different temperatures
Given the question of which acid (acetic or formic acid) is the most suitable oxygen
carrier for epoxidation reaction, this study found that formic acid shows better
performance than acetic acid as indicated by higher content of epoxy groups with a
3.26% of oxirane content in the epoxidized oil for formic acid. In contrast to early
findings using acetic acid in Section 4.1, however only about 2.62% of maximum
value of oxirane content could be achieved. It seems possible that these results are
due to a different reactivity of acetic acid and formic acid involved in the
epoxidation reaction to produce peroxyacetic acid and peroxyformic acid. At the
first stage before the epoxidation reaction, peroxyacetic acid or peroxyformic acid
were formed from the reaction between hydrogen peroxide and acetic acid or formic
acid as follows:
CH3COOH + H2O2 CH3COOOH + H2O (peroxyacetic acid) (4-15)
HCOOH + H2O2 HCOOOH + H2O (peroxyformic acid) (4-16)
Formic acid and hydrogen peroxide in the reaction mixture will achieve equilibrium
to form peroxyformic acid at a faster rate than acetic acid (Kirk-Othmer, 1965).
Therefore a possibility to react with double bonds in the oil in the next step of the

56. 40
H+
H+
epoxidation reaction will be higher. For this reason, peroxyformic acid was selected
as the best peroxy acid for the epoxidation step at the optimal operating condition at
a reaction time of 4 hour and a batch temperature of 60o
C prior to determining the
optimal condition for the hydroxylation step in the synthesis of polyol.
Another important finding was that at higher reaction times and temperatures than
the optimal conditions a lower oxirane content will result. A possible explanation for
this observation might be that higher reaction times and temperatures favour a high
rate of oxirane ring opening thereby producing epoxidized oil with a lower oxirane
content (Purwanto et al., 2006). Therefore, side reaction products may be formed as
the oxirane ring may be decomposed due to reaction mixture contains materials that
are likely to react with the oxirane rings such as sulfuric acid, formic acid, and water
(Milchert et al., 2009). The unwanted reaction in the epoxidation reaction is
illustrated as follows:
o Hydrolysis reaction:
CH CH + H2O CH CH (4-17)
O OH OH
o Acylation reaction:
CH CH + HCOOH CH CH (4-18)
O OH OCOOH
Reaction temperatures higher than 60o
C result in lower oxirane content indicated by
a reduced amount of oxirane content with reaction time (Figure 4-5). This result may
be explained by the fact that epoxidation reaction using peroxy acid in this case
peroxyformic acid is highly exothermic (Milchert et al., 2009). Hence, high
temperatures during the epoxidation reaction may cause the decomposition rate of
epoxy groups to be higher than the formation rate. As a result, lower epoxy groups
will be produced.

57. 41
4.3 Hydroxylation of Epoxidized RBO (3rd
Study)
During the hydroxylation reaction, epoxy groups in the epoxidized oil are converted
to hydroxyl groups. Hence, the objective function for determining the optimal
condition in the hydroxylation reaction is to maximize the concentration of hydroxyl
groups as indicated by a high hydroxyl value.
4.3.1 Experimental Design and Optimization of the Hydroxylation
Reaction
A full factorial central composite design (CCD) was employed and the total number
of treatment combinations can be represented as 022 nkk
++ (Doddapaneni et al.,
2007).
Where: k
2 = factorial design
k2 = star point
k = the number of independent variables
0n = the number of replications at the centre point
This third study evaluated the effect of two independent variables (reaction time and
temperature) of the hydroxylation reaction on the response variables (hydroxyl value
and viscosity). The central values of the independent variables in the hydroxylation
of epoxidized oil were a batch reaction time of 120 minutes at a temperature of
50o
C. The two independent variables to be optimized were coded 1X and 2X at five
levels (-2, -1, 0, 1, 2) using the equation (4-19).
i
i
i
x
xx
X
∆
−
= 0
(4-19)
Where: iX = the coded value of an independent variable
ix = the real value of an independent variable
0x = the real value of an independent variable at the centre point
ix∆ = the value of step change
The distribution of coded 1X and 2X at five levels is indicated in Table 4-8. At this
stage, 4 points factorial design, 4 star points and 3 replicates at the central points (all

58. 42
factors at level 0) were performed to fit with the second order polynomial model.
Hence, 11 experiments were conducted for the hydroxylation of epoxidized oil.
Table 4-8 The range and levels of variables for hydroxylation reaction
Variables Symbol coded Range and levels
-2 -1 0 1 2
Reaction times (min)
Temperatures (o
C)
1X
2X
40 80 120 160 200
30 40 50 60 70
4.3.2 Statistical Analysis
A second-order polynomial model (Equation 4-20) was fitted to represent the
experimental data presented in Table 4-9.
2112
2
222
2
11122110 XXXXXXY ββββββ +++++= (4-20)
Where )21( −=iYi is the response ( 1Y = hydroxyl value and 2Y = viscosity); 0β is a
constant; 1β and 2β represent the linear coefficients; whilst 11β and 22β are the
quadratic coefficients; 12β is the interaction coefficients.

59. 43
Table 4-9 CCD and response in terms of hydroxyl value and viscosity of polyol
Reaction time
(minute)
Temperature
(o
C)
Hydroxyl value
(mg KOH/g oil)
Viscosity
(cP)
Exp. No.
1X 2X 1Y 2Y
1 -1 -1 126.0 34.3
2 1 -1 158.4 42.7
3 -1 1 152.6 43.8
4 1 1 107.3 61.7
5 -2 0 50.3 42.0
6 2 0 82.3 47.3
7 0 -2 119.2 29.9
8 0 2 136.2 95.3
9 0 0 159.2 43.3
10 0 0 161.5 45.1
11 0 0 159.4 44.5
The software Microsoft Excel was performed to analyze the results in the form
analysis of variance (ANOVA).
For each reaction time and corresponding temperature, the hydroxyl value ( )1Y and
viscosity ( )2Y were measured following the hydroxylation reaction. The correlation
of the responses 1Y and 2Y to coded values of variables was estimated by multiple
linear regression. The obtained regression statistics are presented in Table 4-10 and
the analysis of variance (ANOVA) is provided as Table 4-11. Analysis of regression
statistics and analysis of variance indicated a good fit and significance F < 0.05).

60. 44
Table 4-10 Regression statistics for hydroxyl value and viscosity of polyol
Regression statistics Hydroxyl Value
( )1Y
Viscosity
( )2Y
Multiple R
R Square
Adjusted R Square
Standard Error
Observations
0.971
0.942
0.884
12.399
11
0.945
0.892
0.784
8.142
11
Table 4-11 Analyses Of Variance (ANOVA) for hydroxyl value and
viscosity of polyol
Source DF SS MS F Significance F
Hydroxyl value
(mg KOH/g oil)
Viscosity
(cP)
Regression
Residual
Total
Regression
Residual
Total
5
5
10
5
5
10
12534.6
768.6
13303.2
2737.0
331.4
3068.5
2506.9
153.7
547.4
66.3
16.31
8.26
0.0041
0.018
Table 4-12 Significance of regression coefficients for hydroxyl value of polyol
Coefficients Standard Error t Statistic P-value
Intercept 163.187 6.360 25.657 1.68E-06a)
1X 4.252 3.579 1.188 0.28820
2X 0.775 3.579 0.217 0.83714
2
1X -23.627 2.822 -8.372 0.00040a)
2
2X -8.278 2.822 -2.933 0.03252b)
21 XX -19.419 6.199 -3.133 0.02588b)
a
Significant at 0.1% (p<0.001)
b
Significant at 5.0% (p<0.05)

61. 45
Table 4-13 Significance of regression coefficients for viscosity of polyol
Coefficients Standard Error t Statistic P-value
Intercept 42.875 4.177 10.26582 0.00015a)
1X 3.083 2.350 1.311759 0.24660
2X 13.275 2.350 5.648356 0.00242b)
2
1X 0.174 1.853 0.09381 0.92890
2
2X 4.670 1.853 2.520 0.05317
21 XX 2.380 4.071 0.585 0.58423
a
Significant at 0.1% (p<0.001)
b
Significant at 1.0% (p<0.01)
c
Significant at 5.0% (p<0.05)
The model is a good fit of the experimental data as indicated by the high values of
the correlation coefficients (R2
) for the responses. The data analysis for regression
was undertaken using Microsoft Excel whereas Matlab plotting software was
employed to visualize the results.
4.3.3 Effects of Reaction Time and Temperature on Hydroxyl
Value
The empirical relationship between hydroxyl value and the two independent
variables (reaction time and temperature) in coded units is illustrated as:
21
2
2
2
1211 419.19277.8626.23775.0252.4187.163 XXXXXXY −−−++= (4-21)
Based on Table 4-12, all the observed data was significant at p < 0.05. The results of
this study indicate that hydroxyl value is a quadratic function of reaction time and
temperature.

62. 46
H+
+
+
.. +
Figure 4-6 Effects of reaction time (X1) and temperature (X2) on hydroxyl value
of polyol
The hydroxylation reaction using acid catalyst follows SN1 mechanism of reaction
with the formation of carbocation (Solomons, 1992). There are three main steps in
the opening ring of oxirane of epoxidized oil using acid catalyst. The detail of each
step is summarized as follows:
Step 1:
C C C C (carbocation) (4-22)
O O
H
Step 2:
C C + H O H HO C C O H (4-23)
O H
H

63. 47
+
.. +
+
..
+
+
+
-H+
-H+
+ -H+
C C + CH3OH HO C C OCH3 (4-24)
O H
H
CH3
C C + CH3CHCH3 OH C C O CH (4-25)
O OH H CH3
H
Step 3:
HO C C O H OH C C OH (4-26)
H
HO C C OCH3 OH C C OCH3 (4-27)
H
CH3 CH3
OH C C O CH OH C C O CH (4-28)
H CH3 CH3
The maximal hydroxyl value was achieved at a coded reaction time 0.137 and at
coded temperature -0.113. These coded values were determined by finding
stationary points by calculation of partial derivatives of the polynomial equation for
the hydroxyl value. The real values of variables at the optimal operating condition in
the hydroxylation reaction were deduced by converting the coded values to their
original values using equation (4-19). The optimal condition for hydroxylation
reaction occurred with reaction time of 126 min at temperature of 49 o
C and
produced a polyol with a maximum hydroxyl value of 161.5 mg KOH/g oil. The
result suggests that RBO is suitable as a potential feedstock for polyol production
compared to previous research by Petrovic et al. (2003) for epoxidation of corn oil
resulted a polyol with hydroxyl value of 140 mg KOH/g oil.

64. 48
As illustrated in Figure 4-6, the hydroxyl value of hydroxilated oil (polyol) increases
with reaction time and temperature and then that value reaches an optimal level.
After that, the hydroxyl value decreases with reaction time and temperature.
Setyopratomo et al., (2006) have also reported a similar behaviour for polyol
synthesis from palm oil. A possible explanation is that after attaining the optimal
condition, the hydroxyl groups were substituted by a strong nucleophile CH3O-
from
methanol excess in the mixture, as nucleophile CH3O-
is stronger than nucleophile –
OH. Below is the level of reactivity for some nucleophiles according to Solomon
(1992):
RO-
> HO-
>> RCO2
-
> ROH > H2O
Another possible explanation for this might be that the obtained hydroxyl groups
react with epoxy groups (Kiatsimkul et al., 2008). Explanation regarding this reason
will be discussed more in Section 4.3.4.
4.3.4 Effects of Reaction Time and Temperature on Viscosity of
Polyol
The experimental data of central composite design was fitted with a second-order
polynomial model by performing multiple linear regressions. The correlation
between viscosity of polyol products ( 2Y ) and the two independent variables
(reaction time and temperature) in coded units after applying of response surface
methodology can be correlated by the following equation:
21
2
2
2
1212 380.2670.4174.0275.13083.3875.42 XXXXXXY +++++= (4-29)
Where 2Y (viscosity of polyol in centipoise (cP)) is the response and 1X , 2X are the
coded values of independent variables (reaction time and temperature, respectively).

65. 49
Figure 4-7 Effects of reaction time (X1) and temperature (X2) on viscosity of polyol
The result shows that the viscosity of polyol increases linearly with the rise of
temperature and this effect are positive and significant at p < 0.01 for temperature
effect only (Table 4-13). As can be seen from Figure 4-7 the viscosity of polyols
increases with reaction time and temperature and at a faster rate with temperature
than with reaction time. Through the hydroxylation reaction, viscosity of polyols
increases with reaction time and temperature until the optimal condition is attained,
as hydroxyl groups were introduced into epoxy groups to produce polyol with higher
molecular weight. In this research, results indicate that after achieving the optimal
hydroxyl value, the viscosity of polyols increases with reaction time and
temperature. A possible explanation for this might be that unexpected reaction take
place in the mixture such as polymerization or cross linking. Molecular weight or
chain length is the key factor influences the viscosity of polymer materials. The
viscosity of polymers increases with molecular weight or chain length (Billmeyer,
1984). In the mixture, hydroxyl groups may react with oxirane groups through the
reaction depicted below (Kiatsimkul et al., 2008):

66. 50
OR’
OR’ RC CR’’
RC CR’’ + R’’’C CR’’’’ O (4-30)
OH O R’’’C CR’’’’
OH
This reaction may result in a product with higher molecular weight and will produce
polyols with higher viscosity. The viscosity of polyols in this research is in the range
between 29.9 – 95.3 cP and is considered as a reasonable viscosity. This study
confirms that the viscosity of polyol resulted from this research is close to the
typical characteristic of methyl esters polyol with viscosity of 0.1 Pa.s (100 cP)
(Petrovic, 2008). The viscosity of the polyol product in this research is lower than
another type of polyol 173 with viscosity of 5 Pa.s (5000 cP) undertaken by Petrovic
(2008). A possible explanation for this might be that as methanol was present in the
reaction, it may cause a transesterification reaction as methanol is the most reactive
alcohol (Petrovic et al., 2003). Thus, methyl ester polyol with lower viscosity
product will result. Thus, the amount or ratio of alcohol is a crucial factor in the
hydroxylation step to achieve polyol with desirable viscosity.
Figure 4-8 Sample of polyol produced

67. 51
Figure 4-8 shows the sample of polyol product synthesized from rice bran oil
through epoxidation and hydroxylation reactions. The current conclusion is that the
economic value of rice bran oil could be increased by converting it to a polyol
product through epoxidation and hydroxylation reactions. The result suggests that
RBO is suitable as a potential feedstock for production of polyol. The starting RBO
with iodine value of 98.2 g I2/100g oil could attain maximal hydroxyl value of 161.5
mg KOH/g oil.

68. 52
5 CONCLUSIONS
This research report has considered the possibility to use rice bran oil as a potential
feedstock for polyol production to increase its economic value. This project was
undertaken to determine the optimal operating conditions in the epoxidation and
hydroxylation steps to produce a polyol synthesized from RBO. Two initial studies
have found that generally the reaction conversion in the epoxidation reaction using
peroxyacetic acid and peroxyformic acid increases with reaction time and
temperature. A detailed study of the epoxidation step with the use of formic acid as
an oxygen carrier was performed and the kinetic parameters for a pseudo-first order
model were determined at 40, 50, 60, 70 and 80o
C. The measured reaction rate for
epoxidation with peroxyformic acid were 0.172h-1
(40o
C), 0.304h-1
(50o
C), 0.374h-
1
(60o
C), 0.425h-1
(70o
C) and 0.492h-1
(80o
C). The activation energy of epoxidation
with peroxyformic acid was found to equal 22.6 kJ/mol and the epoxidation reaction
was pseudo-first order with respect to the concentration of double bonds in the oil.
The oxirane content of epoxidized oil was also studied in the second study and the
result revealed that the oxirane content, represented by oxirane groups, increased
with reaction time and temperature to a maximum and then declined after achieving
the optimal point. The optimal condition for epoxidation reaction using peroxyacetic
acid was achieved at a reaction time of 4.3 hour and temperature of 63.8o
C, whereas
with peroxyformic acid it was achieved at a reaction time of 4 hour and temperature
of 60o
C. Another important finding is that formic acid produced a maximal oxirane
content of 3.26% was found to show improved performance compare to acetic acid
with an optimal oxirane content of only 2.62%. The final study for the hydroxylation
step has shown that the hydroxyl value of polyol is a quadratic function of reaction
time and temperature and the optimal condition was achieved at reaction time of
125.5 minute and temperature of 49o
C. In terms of polyol viscosity, this value
increased with reaction time and temperature with viscosity in the range of 29.9 –
95.3 cP and temperature was found to have the most significant effect on the
viscosity of polyol. Response surface method (RSM) was employed to determine the
optimal condition in the epoxidation with peroxyacetic acid and in the hydroxylation
step. This optimization was time saving, less complex, and yet highly efficient.

69. 53
6 RECOMMENDATIONS FOR FUTURE RESEARCH
It is recommended that further research be undertaken in the following areas:
o To investigate other factors that influence in the epoxidation reaction such as
mole ratio of hydrogen peroxide to oil, mole ratio of oxygen carrier to oil,
stirring speed, kinds and concentration of catalyst to achieve a high content
of epoxy groups in the epoxidized oil.
o To perform other methods achieving a high amount of oxirane groups in the
epoxidation step such as using metal as a catalyst.
o To investigate significant factors that have an effect on the hydroxylation
reaction to achieve a desirable viscosity of polyol such as the amount or ratio
of alcohol and water to the oil.
o To devise a process flow sheet and to perform an economic analysis of the
likely cost of an optimized process for the product of polyol from rice bran
oil.