green catalysts 2013
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Green Catalysts 2013TRANSCRIPT
GREEN CATALYSTS FOR THE PRE-TREATMENT OF
LOW GRADE CRUDE PALM OIL
ADEEB HAYYAN ALRAZZOUK
KHA100126
A THESIS SUBMITTED IN FULFILMENT OF THE
REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
FACULTY OF ENGINEERING
UNIVERSITY OF MALAYA
KUALA LUMPUR
2012
ii
ORIGINAL LITERARY WORK DECLARATION
Name of Candidate: ADEEB HAYYAN ALRAZZOUK (I.C/Passport No.: 006524507)
Registration/Matric No.: KHA100126
Name of Degree: Doctor of Philosophy (Ph.D.)
Title of Project Paper/Research Report/Dissertation/Thesis (“this Work”):
GREEN CATALYSTS FOR THE PRE-TREATMENT OF LOW GRADE CRUDE
PALM OIL
Field of Study: Chemical Engineering
I do solemnly and sincerely declare that:
(1) I am the sole author/writer of this Work;
(2) This Work is original;
(3) Any use of any work in which copyright exists was done by way of fair dealing and for
permitted purposes and any excerpt or extract from, or reference to or reproduction of any
copyright work has been disclosed expressly and sufficiently and the title of the Work and its
authorship have been acknowledged in this Work;
(4) I do not have any actual knowledge nor ought I reasonably to know that the making of
this work constitutes an infringement of any copyright work;
(5) I hereby assign all and every rights in the copyright to this Work to the University of
Malaya (“UM”), who henceforth shall be owner of the copyright in this Work and that any
reproduction or use in any form or by any means whatsoever is prohibited without the written
consent of UM having been first had and obtained;
(6) I am fully aware that if in the course of making this Work I have infringed any
copyright whether intentionally or otherwise, I may be subject to legal action or any other
action as may be determined by UM.
Candidate’s Signature Date: 21-11-2012
Subscribed and solemnly declared before,
Witness’s Signature Date: 21-11-2012
Name:
Designation: Department of Chemical Engineering,
Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
Tel. /Fax: +60 123002949/+60 379675311
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ABSTRACT
Exploring new bio-sources for fuel production is one of the priorities of
industrial oriented research. Alternatively, there are large amounts of acidic
crude palm oil (ACPO) with high FFA content produced from industrial mills
of oil palm. These could be converted to fatty acid methyl esters (FAME). The
main obstacle against producing biodiesel from ACPO is its high FFA content.
Therefore, it is required to undergo a pre-treatment stage in order to convert the
FFA into fatty acid methyl ester (FAME) before proceeding for biodiesel
production. An acid-catalyzed esterification process was carried out in
pretreatment of ACPO with alcohol to esterify the free fatty acid (FFA) before
trasestifying the triacylglycerols (TAG) with an alkaline catalyst to produce
biodiesel fuel. In this study, characterization of ACPO was investigated in
terms of fatty acid composition and physical properties. The first phase in this
study was screening of different types homogenous acids such as
ethanesulfonic acid (ESA), methanesulfonic acid (MSA), chromosulfuric acid
(CSA), benzenesulfonic acid (BZSA) and toluene-4-sulfonic acid monohydrate
(PTSA). The second phase of this study is conversion of selected homogenous
acid such as PTSA to deep eutectic solvent (DES) in order to improve the
physical properties of the acid. Different types of ammonium such as choline
chloride and phosphonium salts such as allyltriphenylphosphonium bromide
were used to prepare DES. DES was introduced as a solvent and catalyst in
esterification reaction of ACPO. This study develops a pre-treatment process
using DES to reduce the free fatty acid to the minimum acceptable limit for
biodiesel production. Conversion of PTSA to DES was improved the physical
properties of PTSA and this DES shows high catalytic activity in the
esterification reaction. There are unlimited possibilities, studies and
applications to synthesize potential DES for esterification and
transesterification reactions of wide range of oils and fats. The biodiesel
produced from ACPO was favorable as compared to EN 14214 and ASTM
D6751 standards.
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ACKNOWLEGMENTS
In the name of Allah, the Most Gracious and the Most Merciful.
In the first place, all the praises and thanks are to Allah Almighty for
granting us success in this work and giving us patience and strength to
complete this study as a fulfillment of the requirement of Doctorate of
Philosophy in Chemical Engineering successfully.
The author would like to extend his sincere thanks and gratitude to the
head of Centre for Ionic Liquids (UMCiL), Professor Dr. Mohd Ali Hashim for
his continued support, supervision, encouragement and valuable guidance
throughout the duration of this research study. The author wishes to express his
profound appreciation and gratitude to Assoc. Prof. Dr. Inas M. AlNashef and
Assoc. Prof. Dr. Farouq S. Mjalli for their support.
Finally, the author presents his most sincere thanks and warmest
gratitude to the great parents (may ALLAH SWT bless and reward them). The
warm gratitude and thanks are extended to all other author’s family members,
especially his wife, for their support during the period of study.
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TABLE OF CONTENTS
CHAPTER 1: INTRODUCTION ........................................................... 1
1.1 Overview
1.2 Problem Statement and Its Significance ........................................... 4
1.3 Research Philosophy............................................................................. 5
1.4 Research Objectives ............................................................................... 6
1.5 Problem Methodology ............................................................................. 6
1.6 Out Line of Thesis .................................................................................. 7
CHAPTER 2: LITERATURE REVIEW ................................................. 8
2.1 History Background of Biodiesel ........................................................... ..8
2.2 Definitions and Characteristics of Biodiesel Fuel ………………….10
2.3 Merits of Biodiesel Fuel .......................................................................... 11
2.4 Principal of Biodiesel Production……………………………………..12
2.4.1 Chemistry of Esterification Reaction .................................................. 13
2.4.2 Chemistry of Transsterification Reaction ............................................ 33
2.5 Overview of Cheap Sustainable Sources……………………………...17
2.6 Pre-treatment Processes of Oils and Fats………………………………20
2.6.1 Pre-treatment of oils and fats by esterification reaction…………......21
2.6.2 Pre-treatment of oils and fats using adsorbents…………….………..25
2.6.3 Pre-treatment Using Alkaline Neutralization…………….………….26
2.6.4 Pre-treatment of oils and fats by heating (Drying)…………………..26
2.6.5 Pre-treatment of oils and fats by column chromatography……….…28
2.6.6 Pre-treatment of oils and fats by glycerolysis……………………….28
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2.6.7 Pre-treatment of Oils and Fats Using Ultrasonic Energy…….………29
2.6.8 Pre-treatment of oils and fats using microwave energy………..……..30
2.6.9 Pre-treatment of oils and fats using sequence (multi) methods…..…..31
2.6.10 Degumming and Dewaxing of crude oils……………….…………..32
2.7 Pre-treatment Processes of Crude Biodiesel…………………………....33
2.7.1 Pre-treatment of Crude Biodiesel Using Microwave…………….……33
2.7.2 Pre-treatment of Crude Biodiesel Using Acid Neutralization…………34
2.7.3 Pre-treatment of Crude Biodiesel Using Rotary Evaporator…………..34
2.8 Factors Affecting the Pre-Treatment Process…………….………………35
2.8.1 Effect of Catalyst Type…………………………………………………36
2.8.2 Effect of Molar Ratio………….………………………………………..38
2.8.3Effect of Reaction Temperature…………………………………………39
2.8.4 Effect of Reaction Time…..……………………………………………..41
2.8.5 Effect of Stirrer Speed………………………………………………….42
2.9 Effect of the Pre-Treatment Process on the Transesterification Reaction
………………………………………………………………………..………43
2.10 Quality Control and the Limits of Pre-Treatment Process…….……….44
2.11 Recent Development of Acidic Catlaysts and their Challenges……….44
7. Summery and Remarks…………………………………..………………..46
CHAPTER 3: MATERIALS AND METHODS ..................................... 48
3.1 ASPO Sample Collection and Preparation……..……………………..48
3.2 Materials ................................................................................................. 48
3.3 Chemical Analytical Analysis …51
3.4 Synthesis of ChCl-DES……………………………………………………51
3.5 Synthesis of Biodiesel from ACPO
…………………………………………………………………………51
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CHAPTER 4: RESULTS AND DISCUSSION ....................................... 54
4.1 Characteristics of ACPO Physical properties of
ACPO………………………………..……….54
4.2. Screening of Different Types of Acids………………………………..…58
4.2.1 Effect of ESA Catalyst………………………………………………..58
4.2.2 Effect of MSA Catalyst ……………………………………………….65
4.2.3 Effect of CSA
Catalyst………………………………………………………………………..71
4.2.4 Effect of BZSA in the Reduction of FFA in ACPO
………………………………....................................................……………75
4.2.4 Effect of PTSA in the Reduction of FFA in ACPO (Presented in 2nd
International Conferences on Process Engineering and Advanced Materials
2012)…………………………………………………………………………..82
4.2 Conversion of Homogenoues Acids to DES………………………..86
4.2.1 PTSA converison to DES using phosphonium Salt
............................................................................……………………………86
4.4 PTSA converison to DES using Ammonium Salt
..........................………………………………………………………………..98
CHAPTER 5: CONCLUSIONS AND RECOMMENDATIONS 106
5.1 Study of ACPO Characteristics…………………………………..……..106
5. 2 Screening of Homogenous Acids………………………………………107
5.3 Development of Homogenous Acids via Conversion to DES…………108
Bibliography……………………………………………………………….110
APPENDIX A List of Achievements……………………………………….120
1
1 CHAPTER I
INTRODUCTION
1.1 Overview
Biodiesel is a promising biofuel made from natural bioresources such as
vegetable oils and animal fats (Demirbas, 2009; Hayyan et al., 2010a).
Malaysia being one of the largest world palm oil producers and exporters, has
the potential of leading the palm oil biodiesel production sector (Kalam and
Masjuki, 2002; Chew and Bhatia, 2008; Hayyan et al., 2011). Crude palm oil
(CPO) was used as an industrial raw material for biodiesel production because
of its availably as a product of industrial mills. CPO after the milling process is
non-edible due to its high FFA and impurities content. Hence, CPO is usually
sent to the refinery for further processing and purification. CPO is
conventionally used as a raw material for biodiesel production (Elsheikh et al.,
2011; Crabbe et al., 2001). According to annual statistical reports of MPOB
(Malaysian palm
oil board, 2010) the estimated production of CPO reached 17.5 million metric
tons in 2010. This report highlighted the fact that international prices of CPO
were fluctuating according to CPO global market demand. CPO is the raw
material for refined palm oil processing industries. Moreover, the composition
of CPO involves important constituents with high concentrations such as
carotenoids, tocopherols, tocotrienols, sterols, phospholipids, triterpene
alcohols, squalene, aliphatic alcohols and aliphatic hydrocarbons (Goh et al.,
1985; Gunstone, 2002). CPO value as an edible ingredient for refined palm oil
increases its economical importance. Due to limited annual production of CPO
and the increasing global market demand, the priority for palm oil mills is to
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sell CPO to palm oil refineries as a raw material for food processing. In view of
the above mentioned facts, many obstacles exist for the commercialization of
biodiesel produced from CPO. Hence, finding and highlighting new bio-
industrial resources for biodiesel production is one of the urgent priorities of the
industrial and academic community in order to make biodiesel production
economical and commercially feasible. Acidic crude palm oil (ACPO) is an
unfavorable type of CPO produced from palm oil mills due to different
operational and processing factors. Possible reasons for producing ACPO
involve technical milling problems, long time oil storage, delay of fruit
harvesting, unexpected climate changes, in addition to the variation of storage
environment and temperature. Usually, CPO with FFA lower than 5% is
considered as an acceptable CPO grade which can be sent directly to the palm
oil refinery. ACPO has an FFA content higher than 5% and consequently it
needs to undergo a pre-treatment stage to remove the high FFA before
proceeding to other palm oil refinery processing stages. FFA content is the
controlling key factor for pricing different verities of oils and fats. ACPO as an
agricultural raw material with a much lower price compared to CPO due to the
unfavorable higher FFA content of ACPO in addition to existence of other
undesirable impurities. From an economical point of view, ACPO is a
significant raw material for biodiesel production which can reduce the total cost
of biodiesel processing. Based on the abovementioned discussion, this study
proposes ACPO as a cheap alternative raw material for the biodiesel industry.
The cost of feedstock accounts for 60–75% of the total production cost of
biodiesel fuel (Krawczyk, 1996; Ma and Hanna, 1999).
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ACPO is a promising renewable raw material for biodiesel production which
can significantly reduce the total cost of biodiesel processing due to the huge
quantity of ACPO produced from the palm oil industry. The remaining cost is
related to processing expenses. Exploring ways to enhance process economy in
terms of reactor development and reaction engineering are the foci of current
biodiesel research studies. Catalyst technology has significant effect on the
biodiesel production industry. Many attempts have been made to produce
biodiesel using different types of homogenous catalysts such as
methanesulfonic acid and sulfuric acid (Aranda et al., 2008), as well as
heterogeneous catalysts such as tri-potassium phosphate (Guan et al., 2009).
Lipase enzyme was used as a biocatalyst in the esterification of high FFA
content of oils and fats for biodiesel production (Vieira et al., 2006).
Traditionally, sulphuric acid is used as the conventional catalyst in
esterification reactions to reduce the FFA content to the minimum level for
alkaline transesterification reactions (1% FFA is recommended) (Canakci and
Gerpen, 2001; Hayyan et al., 2011a). Many attempts have been made to
produce biodiesel using new types of catalysts such as ionic liquids (Elsheikh et
al., 2011). Ionic liquids (ILs) were used recently as catalysts and solvent in
organic reactions such as esterification reaction (Yue et al., 2011). ILs were
studied as catalysts to treat the crude palm oil for biodiesel production
(Elsheikh et al., 2011; Man et al., 2013). However, the problem associated with
using ILs in the biodiesel production is their high synthesis cost. Deep eutectic
solvents (DESs) are considered as a new generation of ILs, or their alternatives,
which gained enormous interest in both academic research as well as in
industrial applications. DESs are cheaper than conventional ILs due to easy
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procedure of preparation (Cooper et al., 2004). In addition, DESs share with ILs
other environmental merits such as biodegradability and non-flammability (Hu
et al., 2004; Abbott et al., 2008; Olivier-Bourbigou et al., 2010). A DES can be
prepared via mixing of hydrogen bond donor (HBD) such as urea and salt such
as choline chloride (ChCl) (Abbott et al., 2003). ChCl is the common salt used
for preparation of DES with a wide range of HBDs. Nevertheless, limited
studies were found in the literature for using DES as a catalyst in chemical
reactions. For instance, a ChCl-based DES was used as a catalyst in the carbon–
carbon bond formation in the rapid synthesis of β-hydroxy functionalized
derivatives (Singh et al., 2012). However, DES was not yet studied as catalyst
for pre-treatment of industrial acidic oils such as ACPO for biodiesel
production.
1.2 Problem Statement and Significance of Study
Acidic crude palm oil has an FFA content higher than 5% up to 15%. Above
this limit the oil is consider as SPO. ACPO is a promising renewable raw
material for biodiesel production which can significantly reduce the total cost
of biodiesel processing due to the huge quantity of LGCPO produced from the
palm oil industry.
The main obstacle against producing biodiesel from LGCPO is its high FFA
content. Due to this acidic oil high FFA content, it is required to undergo a pre-
treatment stage in order to convert the FFA into fatty acid methyl ester (FAME)
before proceeding to other palm oil refinery processes or for biodiesel
production.
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DES containing PTSA as a hydrogen bond donor has not been investigated
as a reaction solvent and as a catalyst for the practical FFA reduction in
industrial acidic oils, such as ACPO. Although PTSA has been used as a
catalyst in esterification reactions, its hygroscopic nature and storage and its
handling difficulties have prevented its commercial usage. Conversion of solid
organic acids such as PTSA into DES using simple technique will provide
opportunity to improve a wide range of catalysts in esterification and a host of
other chemical reactions. In addition, catalysts based on DESs are potential
alternatives to heterogeneous catalysts and their applications can simplify
downstream operation, such as the elimination of filtration and catalyst pre-
treatment.
There are unlimited research waiting of further studies to carry on
experiments using ILs or DES with wide range of acids for deep investigation
in terms of catalytic activity, recycling study, kinetics study and reaction
parameters. In addition, results of this study using IL supporting technique can
be applied and used for other types of reactions using homogenous catalyst and
potential to increase the selectivity of desired products and reduce the cost of
production significantly via recycling the homogenous catalysts.
1.3 Research Philosophy
It is vital to target the direct utilization energy for domestic and industrial
applications. A recent literature survey by the authors reveals a big gap between
the availability of different energy resources and their potential applications.
Technology is the main link between earth energy sources and their
applications. Therefore, improvement of technology using available sources to
generate energy is the main focal issue in research concerning energy and fuel.
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Biodiesel to be produced form available industrial feedstock such as ACPO will
decrease the production cost of biodiesel fuel. Production of biodiesel using
simple, cheap, safe, green and environmental technique will improve the role
of Biodiesel as alternative fossil fuel in the next era. Development of catalyst is
considered as one of the main contribution in pre-treatment biodiesel
processing. Conversion of organic acids such as PTSA into DES using simple
technique will provide opportunity to improve a wide range of catalysts in
esterification and a host of other chemical reactions.
1.4 Research Objectives
The objectives of this research are:
1. To treat the high acidic oils via esterification process and to reduce the
FFA content to the minimum acceptable limit for biodiesel production.
2. To investigate and characterize a new industrial raw materials for
biodiesel production. To develop this raw material via dilution with different
types of oils.
3. To investigate the catalytic activity and other operation conditions of
new liquid and solid acids and to screen the conventional acidic catalysts in
FFA content reduction.
4. To convert of selected homogeneous acids to DES for improvement of
physico-chemical properties. To investigate the catalytic activity of these types
DES in the esterification reaction.
1.5 Research Methodology
The specific stages of the research methodology are as listed below:
1) Characterization of ACPO in terms of chemical and physical properties.
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2) Screening of different types of acids. Investigation of optimum
conditions for esterification and transesterification processes using single factor
optimization.
3) Selection of potential acid catalyst for further improvement of
esterification process.
4) Conversion of acid to DES and application this DES in the pre-treatment
of ACPO for biodiesel production.
5) Study the effect of DES to different of operating conditions such as
solvent dosage, molar ratio, reaction time, reaction temperature and recycling
runs of DES after reaction.
6) Characterization of optimum product according to international standards
specifications of biodiesel fuel.
1.6 Outline of the Thesis
This thesis comprised five chapters, as follows:
Chapter I includes a brief background on biodiesel production from acidic raw
materials. The problem statement and philosophy of the research work are
mentioned followed by the objectives of the research, and finally the research
methodology. Chapter II discusses the background of biodiesel; methods of
FFA content reduction; its catalysts used and previous works done in
esterification with high acidic oils and fats. Chapter III discusses the detailed
research methodology of biodiesel production from ACPO and preparation of
DES. Materials, chemicals, equipment and analytical instruments involved in
the pre-treatment of ACPO using esterification reaction. Chapter IV comprises
the results and discussions. Chapter V includes conclusions and
recommendations for future work.
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2 CHAPTER II
LITERATURE REVIEW
2.1 Historical Background of Biodiesel
Transesterification of a vegetable oil was conducted as early as 1853, by
scientists E. Duffy and J. Patrick, many years before the first diesel engine
became functional. Life for the diesel engine began in 1893 when the famous
German inventor Dr. Rudolf Diesel published a paper entitled “The theory and
construction of a rational heat engine” (Gunstone and Hamilton, 2001). What
the paper described was a revolutionary engine in which air would be
compressed by a piston to a very high pressure thereby causing a high
temperature. Dr. Diesel designed the original diesel engine to run on vegetable
oil. Diesel received a patent in 1893 and demonstrated a workable engine in
1897. Today, diesel engines are classified as “compression-ignition” engines.
Dr. Diesel’s prime model, a single 3 m iron cylinder with a flywheel at its base,
ran on its own power for the first time in Augsburg, Germany on August 10,
1893. Diesel later demonstrated his engine and received the “Grand Prix”
(highest prize) at the World Fair in Paris, France in 1900 (Gunstone and
Hamilton, 2001). This engine stood as an example of Diesel’s vision because it
was powered by peanut oil, a biofuel, though not strictly biodiesel, since it was
not transesterified. Dr. Diesel believed that the utilization of a biomass fuel was
the real future of his engine.
In a 1912 speech, Dr. Diesel said “the use of vegetable oils for engine fuels
may seem insignificant today, but such oils may become, in the course of time,
as important as petroleum and the coal-tar products of the present time”. Dr.
Diesel pointed out ‘in any case, they (vegetable oil) make it certain that motor-
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power can still be produced from the heat of the sun, which is always available
for agricultural purposes, even when all our natural stores of solid and liquid
fuels are exhausted’. Up to approximately 1950, numerous other reports exist
on the use of vegetable oils as biofuel. The background at that time, as already
mentioned by Dr. Diesel (1912b), was largely that several European nations
wanted to provide their colonies in the tropical climate zone with a certain
degree of energy self-sufficiency. Several reports from that time are
noteworthy. In 1937, Chavanne received a patent on what now would be called
biodiesel. Chavanne (1937) claimed that a mixture of fatty acids and their
glycerol esters was converted into esters with alcohols of low molecular weight
in the presence of an acid catalyst. Acid-catalyzed formation of the ethyl esters
of palm oil was described in some suitable as a liquid fuel. The background of
this work was described by Chavanne (1943) in an additional publication. Van
den Abeele (1942) wrote an extensive report describing synthesis and use of
ethyl esters of palm oil. After 1950, the use of vegetable oils and their
derivatives as diesel fuel remained largely dormant (Gunstone and Hamilton,
2001). After 1950, the use of vegetable oils and their derivatives as diesel fuel
remained largely dormant. Bruwer et al., (1980) reported the use of sunflower
oil esters as alternative diesel fuel. Since about 1980 there has been significant
interest in the utilization of vegetable oils and their derivatives as alternative
fuels. Since the 1980s, biodiesel plants have opened in many European
countries, and some cities have run busses on biodiesel, or blends of petrodisesl
and biodiesel. Recent environmental and domestic economic concerns have
prompted resurgence in the use of biodiesel throughout the world. Commercial
production of biodiesel fuel did not begin until the late 1990. In 1991, The
10
European community proposed a 90% tax deduction for the use of biofuels,
including biodiesel. Biodiesel plants are now being built by several companies
in Europe; each of these plants will produce up to 1.5 million gallons of fuel per
year. The European Union accounted for nearly 89% of all biodiesel production
worldwide in 2005 (Demirbas, 2009a).
2.2 Definitions and Characteristics of Biodiesel Fuel
Biodiesel made from renewable biological sources, such as vegetable oils,
animal fats (Ma and Hanna, 1999; Demirbas, 2009a). Biodiesel, defined as
“substitute for, or an additive to diesel fuel that is derive from the oils and fats
of plants and animals. Chemical definition of biodiesel is “monoalkyl esters of
long chain fatty acids derived from a renewable lipid feedstock, such as
vegetable oil or animal fat” according to the American Society for Testing and
Materials (ASTM). “Bio” represents its renewable and biological source in
contrast to traditional petroleum-based diesel fuel; “diesel” refers to its use in
diesel engines. Biodiesel is known as monoalkyl, such as fatty acid methyl ester
(FAME) and fatty acid ethyl esters (FAEE) derived from a renewable lipid
feedstock, such as vegetable oil or animal fat (Demirbas, 2009a). Biodiesel is a
mixture of methyl esters of long chain fatty acids like lauric, palmitic, steric,
oleic, etc. Typical examples are palm oil, rapeseed oil, canola oil, soybean oil,
and sunflower oil and its derivatives from vegetable sources. Beef and sheep
tallow and poultry oil from animal sources and cooking oil are also the sources
of raw materials. Biodiesel reaction is a reaction between oil or fat with alcohol
the presence of catalyst alkaline or acid to form biodiesel, and glycerin and this
reaction call transesterification reaction. The common international standard for
biodiesel is EN 14214 and ASTM D6751 (Hayyan et al., 2010). Biodiesel can
11
be used as B100 (neat) or in a blend with petrodiesel. A blend of 20 % biodiesel
with 80 % petrodiesel, by volume, is termed “B20”. A blend of 2% biodiesel
with 98 % petrodiesel is “B2”, and so on. The higher heating values of
biodiesels are relatively high. The higher heating values of biodiesels (39–41
MJ/kg) are slightly lower than that of gasoline (46 MJ/kg), petrodiesel (43
MJ/kg) or petroleum (42 MJ/kg), but higher than coal (32–37 MJ/kg)
(Demirbas, 2009a). Biodiesel is a clear amber-yellow liquid with a viscosity
similar to petrodiesel. It can be used as a fuel in diesel engine without any
modification. Biodiesel has physical properties very similar to petroleum-
derived diesel fuel, but its emission properties are superior. Using biodiesel in a
conventional diesel engine substantially reduces emissions of unburned
hydrocarbons, carbon monoxide, sulfates, polycyclic aromatic hydrocarbons,
nitrated polycyclic aromatic hydrocarbons, and particulate matter. Diesel blends
containing up to 20% biodiesel can be used in nearly all diesel-powered
equipment, and higher-level blends and pure biodiesel can be used in many
engines with little or no modification (Demirbas, 2009a). The most common
blend is a mix of 20% biodiesel with 80% petroleum diesel, or B20 under
recent scientific investigations; however, in Europe the current regulation
foresees a maximum 5.75% biodiesel (Demirbas, 2008; 2009a; Gunstone and
Hamilton, 2001).
2.3 Merits of Biodiesel Fuel
Generally there are five primary reasons for encouraging the development of
biodiesel It provides a market for excess production of vegetable oils and
animal fats.
12
i. It decreases the country's dependence on imported petroleum.
ii. Biodiesel is renewable and does not contribute to global warming due to
its closed carbon cycle.
iii. The exhaust emissions from biodiesel are lower than with regular diesel
fuel.
iv. Biodiesel has excellent lubricating properties.
2.4 Principal of Biodiesel Production
The principal methods of are by esterification reaction as shown in Equation
(2.1). This reaction was recommended if the oils or fats contain high FFA
(Canakci and Van Gerpen, 2001). The esterification reaction is as follows:
FFA + Methanol FAME + Water (2.1)
Another reaction is transesterification and this reaction is conventional reaction
to produce biodiesel fuel if FFA low in oils and fats. The transesterification
reaction is as follows in Equation (2.2):
Triacylglycerols + Methanol 3 FAME + Glycerol (2.2)
In the transesterification reaction, TG is converted to three individual esters.
Transesterification reactions can be base, acid or enzymatic catalyzed.
Transesterification is sometimes called alcoholysis, or if by a specific alcohol,
by corresponding names such as methanolysis or ethanolysis. The base-
catalyzed reaction takes about one hour at room temperature. Acid- catalyzed
13
and enzymatic transesterification require three to four days to complete
(Turner, 2005). A combined strategy called the two-stage process can be used
to maximize the amount of biodiesel produced, while minimizing the amount
of soap produced. The first stage is acid-catalyzed esterification of FFA and
followed by base-catalyzed transesterification. This approach is especially
effective for oils and fats which have high FFA content.
2.4.1 Chemistry of Esterification Reaction
Fatty acid esterification, which is known as Fischer esterfication as
shown in Equation (2.3), the overall equation is as follows:
RCOOH + CH3OH RCOOCH3 + H2O
(2.3)
FFA Methanol FAME Water
The esterification may be driven to the right either by using a significant excess
of one of the reactants or by removing one of the products. Water will form as
by product of reaction (Chi, 1999). Water may be removed either by distillation
or by the addition of a dehydrating agent such as magnesium sulfate or
molecular sieves. The mechanism of Fischer esterification involves an acid-
catalyzed nucleophilic acyl substitution. An alcohol is not a strong enough
nucleophile to attack the carbonyl group of a carboxylic acid; however, the acid
catalyst protonates the carbonyl group and activates it toward nucleophilic
attack. Loss of a proton gives the hydrate of an ester. Protonation of the alkoxyl
group allow it to leave as water, this protonated ester then loses a proton, giving
the ester. The mechanism of Fischer esterification of fatty acid by methanol is
illustrated in Equation (2.4) (Chi, 1999).
14
(2.4)
2.4.2 Chemistry of Transesterification Reaction
Vegetable oils and animal fats have remarkably similar chemical structures,
although they may have different flavor and color. Generally, they are the esters
of glycerol in which al1 three hydroxyl groups are esterified by saturated or
unsaturated (Cl2 to C20) long chain fatty acids. These TG can be transesterified
to lower the high viscosity of the oil or fat which otherwise may cause the
coking of the injectors, oil ring sticking and thickening of lubricating oil. The
high viscosity results from the high molar masses of the oils. The
transesterification of vegetable oil or fat lowers the molar mass to one third that
of TG. Typically, the cleavage of the oil or fat reduces the molar mass from
about 900 to 300 and the viscosity from 20cSt to 3-5cSt (Chi, 1999). The
15
reaction can be catalyzed by either base or acid. The overall chemistry of
transesterification with methanol is represented in Equation (2.5). Overall it
involves the interchange of the alkoxide group between an ester and an alcohol
to give a new ester and a new alcohol. The overall transesterification reaction as
shown in Equation (2.5) consists of a number of consecutive and reversible
reactions as follows:
a) The formation of DG Equation (2.5.1)
b) The formation of monoacylglycerol (MG) Equation (2.5.2)
c) The formation of glycerol Equation (2.5.3)
TG Methanol FAME
Glycerol
R = C12 to C20 straight saturated or unsaturated hydrocarbon chins
16
TG Methanol DG
FAME
DG Methanol MG
FAME
MG Methanol Glycerol
FAME
The stoichiometry of the reaction requires a 3:1 molar ratio of alcohol to TG.
Because esters and alcohols appear on both sides of the equation it might be
expected that equilibrium contents would be close to unity. However, the
17
glycerol moiety is usually not such a good nucleophile as the alcohol and
typically only a 6: 1 molar ratio is required to drive the transesterification to >
95% completion (Chi, 1999). Therefore, the presence of MG and DG at the end
of the reaction must be anticipated.
2.5 Overview of Cheap Sustainable Sources
Economic growth is mainly based on the diversity and availability of energy
sources. Energy is essential input for social development of countries and
improving the quality of life (Sahoo et al., 2007). Throughout the technological
age, many industrialized countries have focused on utilizing the earth’s
resources to generate renewable energy (Hayyan et al., 2008). Since their
exploration, fossil fuels continued to be the major conventional energy source.
The increasing trend of modernization and industrialization resulted in a surge
of growth of the world energy demand. This continuously escalating demand
has drawn the attention to utilize other fuel alternatives such as biodiesel.
Biodiesel as a fuel is receiving an upsurge interest as an alternative, sustainable
and renewable energy resource (Sahoo et al., 2007; Ma and Hana, 1999;
Demirbas, 2009; Hayyan et al., 2010a). Biodiesel has becomes more attractive
as an alternative fuel to petroleum diesel fuel (Pandey, 2009). Moreover,
recently, the increase in crude oil prices has participated in focusing the
attention for considering biodiesel as an alternative, relatively cheaper fuel.
Vegetable oils and animal fats are regarded as the major sources for producing
biodiesel fuels (Ma and Hana, 1999; Canakci and Van Gerpen, 2001). Biodiesel
production has many merits as an alternative, renewable, non-toxic fuel,
biodegradable and environment friendly (Canakci, M., Van Gerpen, 2003;
Hayyan et al., 2009a; Demirbas, 2009). However, various obstacles scenarios
18
have been faced biodiesel production. The availability of resources and the cost
of processing are the most important factors (Krawczyk, 1996; Ma and Hana,
1999; Demirbas, 2009; Hayyan et al., 2010b). The high cost of biodiesel
compared to petroleum diesel has been a major obstacle for the
commercialization of biodiesel (Canakci and Van Gerpen, 2001; Hayyan et al.,
2010a). Currently, edible vegetable oils, such as palm oil, soybean, rapeseed
and sunflower are the prevalent feedstocks for biodiesel production (Antolin et
al., 2002; Hayyan et al., 2010b; Hayyan et al., 2010c). Production of biodiesel
from edible vegetable oil results in the high price of biodiesel. Consequently,
exploring ways to reduce the cost of raw materials is the main focus in current
biodiesel research (Canakci and Van Gerpen, 2001; Canakci, 2007; Hayyan et
al., 2009a; Hayyan et al., 2010c). Mainly, there are three cheap sustainable
sources (CSS) for biodiesel production namely: Non-edible plant oils (Ghadge
and Raheman, 2005; Veljkovic et al., 2006), low grade by-products of oil
refinery industries (Chongkhong, et al., 2007; Echim, et al., 2009; Hayyan et
al., 2009b; Hayyan et al., 2010b) and waste cooking oils (WCO) or waste fats
from restaurants (Leung and Guo, 2006; Canakci and Van Gerpen, 2001;
Canakci, 2007; Bhatti et al., 2008). The use of CSS may lower the cost of
biodiesel production significantly. The problem facing these raw materials is
often the large amount of free fatty acid (FFA) that cannot be converted to
biodiesel using an alkaline catalyst (Canakci and Van Gerpen, 2001; Ma and
Hana, 1999). Usually, raw materials (oils or fats) from CSS are of very low
grade containing water, FFA, impurities and contaminants such as WCO or by-
product of oil industries (Canakci, 2007). However, developing a pre-treatment
process to treat low grade oils and fats from CSS before transesterification
19
process is a crucial step for producing biodiesel within the international
standard specifications of biodiesel fuel (Hayyan et al., 2010b). Imperative
considerations were paid in the selection of raw material, cost analysis pre-
treatment and production processes in biodiesel industry. Pre-treatment
processes are necessary to treat these CSS before biodiesel production by
conventional tranestrification process. Economically, in order to increase the
value of CSS and to decrease the cost of biodiesel production, an economical
pre-treatment process should be taken and studied in terms of cost, performance
and process efficiency before apply the technology in pilot scale. Countries are
looking forward for CSS and governments are supporting the utilization of any
promising local source of energy. The most interesting studies nowadays are
those dealing with discovering new renewable and sustainable energy and
linked with an economically viable technology. Biodiesel industries using low
grade oils or fats contain high FFA need comprehensive investigation on
improving the pre-treatment technologies. The use of CSS with low cost
process technologies will increase the socio-economic and energy management
of the country. Currently, most review studies on biodiesel production present
the most common technologies in the production stage and the effectiveness of
operating conditions (Ma and Hanna, 1999; Meher et al., 2006; Sharma et al.,
2008; Leung et al., 2009; Srivastava and Prasad, 2000). Mainly, pre-treatment
processes can be classified as a chemical pre-treatment such as the
esterification reaction and physical pre-treatment such as drying. There are
many techniques associated with these pre-treatment processes. Depending on
the nature, physical and chemical properties of feedstock, a pre-treatment
process is proposed to treat oils and fats with high FFA content. In this study,
20
the rationale for the variously proposed pre-treatment techniques are reviewed
in terms of their effectiveness, efficiency, merits, effect of conditions and
costing. A brief discussion of selected pre-treatment technologies was included
in order to present advantages and disadvantages of using the technology and to
investigate the potential use of each technology for a pilot plant scale.
2.6 Pre-treatment Processes of Oils and Fats
Different types of pre-treatment technologies have been used to treat oils or fats
prior to alkali transesterification reaction. Pre-treatment processes in the
biodiesel industry usually refer to the esterification reaction. Other pre-
treatment technologies were rarely used in biodiesel industry. The main target
of all pre-treatment technologies is to reduce the FFA content and to prepare
the oils or fats to be applicable chemically and physically to alkaline
transesterification reaction. The initial content of FFA of non-edible plant oils,
low grade byproduct of oil refinery industries and waste oils and fats from
restaurants would not be favorable for biodiesel production as the study by
Canakci and Van Gerpen (2001) indicated that transesterification reaction will
not occur if the FFA content in oil is more than 3%. Other studies reported FFA
content should not be less than 2 or 1% (Hayyan et al. 2010; 2012). Hence it is
necessary to go through some pre-processing of the raw material in order to
bring down the FFA content below this transesterification reaction constraint. In
the subsequent subsections, some details of the most frequently adopted pre-
treatment technologies are highlighted and discussed.
21
2.6.1 Pre-treatment of oils and fats by esterification reaction
During esterification process, FFA is converted to FAME in the presence of
acid catalyst. Whereas TG is converted to FAME through the transesterification
process in the presence of alkaline catalyst. The mechanism for the acid
esterification reaction is shown in Equation 2.6.
)6.2(233 LLLLLOHRCOOCHOHCHRCOOHCataystAcid
+ →←+
At present, fatty acid alkyl esters (FAAE) are obtained by reacting TAG with
lower alcohols, such as methanol or ethanol, in the presence of a strong base
used as catalyst. The reaction yields glycerol as by-product. Oils and fats used
in alkaline transesterification reactions should contain no more than 1% FFA
(Sahoo et al., 2007; Ma and Hana, 1999; Canakci and Van Gerpen, 2001;
Demirbas, 2009). If the FFA level exceeds this threshold, saponification
hinders separation of the ester from glycerol and reduces the yield and
formation rate of biodiesel. A number of researchers have worked on many
types of feedstock that have elevated FFA levels (Canakci and Van Gerpen,
2001). Due to high FFA content in waste cooking oils, the alkali catalyzed
transesterification to produce biodiesel gives low biodiesel yield because FFA
reacts with alkali to form soap, resulting in serious emulsification and
separation problems (Freedman et al., 1984; Canakci and Van Gerpen, 2001;
Demirbas, 2009). Researchers reported that the oil should not contain more
than 1% FFA for alkaline–catalyst transesterification reactions (Freedman et
al., 1984; Ma and Hana, 1999; Canakci and Van Gerpen, 2001; Demirbas,
2009). Pre-treatment of oils or fats before biodiesel production is an important
22
step in the production process especially if the raw material used is waste
cooking oils or oils and fats with high FFA such as palm oil fatty distillate
(Chongkhong et al., 2007), mahua (Ghadge and Raheman, 2005), sludge palm
oil (SPO) (Hayyan et al., 2008; 2009; 2010a), rubber seed oil (Ramadhas et al.,
2004), tobacco (nicotiana tabacum L.) seed oil (Veljkovic et al., 2006), mahua
(madhuca indica) (Ghadge and Raheman, 2005), Karanja (pongammia pinnata)
(Naik et al., 2008), yellow and brown grease (Canakci and Van Gerpen, 2001).
Thus, an acid–catalyzed pre-treatment step by esterification reaction to convert
the FFA to fatty acid methyl ester (FAME) followed by an alkali–catalyzed step
to convert the triglycerides to methyl esters and glycerol should provide an
effective and efficient method to convert high FFA feedstock to biodiesel
(Canakci and Van Gerpen, 2001; Naik et al., 2008). This pre-treatment process
usually utilizes an acid catalyst. The most commonly preferred acid catalysts
are sulfonic, hydrochloric, and sulfuric acid (Ma and Hana, 1999). Organic
sulfonic acid such as p-toluene sulfonic acid (PTSA) (Ma and Hanna, 1999;
Shahidi, 2005) has been used in the pretreatment of SPO (Hayyan et al., 2009)
and to reduce the high FFA content in soybean oil. It was reported that using
6.4x10-5
mol of PTSA as acid catalyst can decrease the FFA content in soybean
oil from 20.5% to 1.1% and the yield obtained after reaction obtained was 48%
with the reaction conditions of 12:1 molar ratio, 180oC reaction temperature,
and 60 minutes reaction time (Di Serio et al., 2008).
23
Table 1: Advantages and disadvantages of common acids used in the pre-
treatment process (esterification reaction) (Paolo, 2001). Acid catalyst Advantages Disadvantages
Sulfuric acid
High catalytic activity.
Low price.
Easy to remove after
neutralization.
Good catalytic activity in
esterification reaction
Corrosion problems.
Possible reaction with double
bonds.
Sulfates are not accepted by
glycerol refiners.
Transesterification very
difficult.
Dark colour of final product.
Hydrochloric
acid
Low price.
Easy to remove after
neutralization.
Suitable to use in esterification
reaction
Corrosion problems.
Dangerous & difficult to
storage and handling.
Forms toxic fumes
PTSA
Medium catalytic activity.
No side reactions with double
bonds.
Reasonable price if commercial
grade and expensive if analytical
grade.
Acceptable colour of final
product.
Good catalytic activity in
esterification reaction
Difficult to remove from
reaction mixture.
Highly hydroscopic powder
Transesterification very
difficult.
Final product will be blanched
24
It can be observed that both acid catalysts sulfuric acid and hydrochloric acid
cause corrosion problems in the chemical reactor and pipelines of the pilot plant
during production of biodiesel, however, PTSA was not reported as corrosive
acid in the biodiesel production. Sulfuric acid was reported to react with the
double bonds of oils and fats. The main disadvantage of using sulfuric acid was
the resulting ash sulfates in the crude glycerol. Purification of glycerol is very
difficult in case the crude glycerol contains sulfates ash. However, the main
advantage of using sulfuric acid in the pre-treatment of oils and fats and
biodiesel production is its high catalytic activity compared to other acid
catalysts in addition to its cheapest cost among other acids. Because of these
merits, sulfuric acid was used widely in pilot plants worldwide.
Hydrochloric acid was reported as the one of the difficult acids to storage and
handling because of its vapor which is very harmful. In addition it is important
to take special care in its handling and storage and use very expensive
containers and sophisticated safety precautions.
The catalytic efficiency of HCl is lower compared to sulfuric acid and PTSA
(Hayyan et al., 2008). However, these disadvantages were not found in PTSA.
The main advantage to propose PTSA as a suitable acid catalyst was the high
activity of PTSA in pre-treatment of oils and fats with high FFA such as SPO.
The FFA content was reduced from 46% to less than 2% FFA using 2% of
PTSA in the pre-treatment of SPO which was suitable to produce acceptable
yield of treated SPO and very pure biodiesel after the transesterification
reaction (Hayyan et al., 2008). However, the main drawback of using PTSA as
acid catalyst is its high price when compared to sulfuric acid. For industrial use,
25
the PTSA cost can be reduced when dealing with large quantities of
commercial grade instead of analytical grade.
Oils pre-treatment using solid catalysts involves an additional cost for the
removal of the spent catalyst from the biodiesel product before using it in
combustion engines. An improper purification process may cause serious
problems such as induced corrosion in the fuel tank, engine, pipes and
eventually wreak havoc on the overall vehicle. In terms of capital cost of the
pre-treatment process, it should be noted that the process with an acid-catalyzed
pretreatment step is more complex in terms of instrumentation due to the
addition of a pretreatment unit to the main production unit (transesterification)
resulting in an increase in the overall plant cost. For these reasons, it is a
common industrial practice to use alkaline-catalyzed processes with fewer and
simpler process equipment units (Leung et al., 2006; Guo et al., 2004).
2.6.2 Pre-treatment of oils and fats using adsorbents
Others methods for the pre-treatment of waste cooking oils exist using different
types of adsorbents such as silica gel, activated carbon, aluminium oxide and
acid –activated spent bleaching earth. These types of adsorbents were used to
reduce some of the poor quality parameters of the oils (Kheang et al., 2006).
Silica gel was found to be the most effective adsorbent in pre-treating waste
cooking oils (Kheang et al., 2006). Pre-treatment of oils and fats by adsorbents
has many advantages such as reducing the FFA in WCO, purifying oils and
fats, reusability, ease of separation in addition to its use for the extraction of
carotenoide as a byproduct of pre-treatment process which has many
commercial uses. Study of by-products of biodiesel production (such as
26
glycerol and carotenoide) will assess the direct and indirect impacts on the
national economy.
2.6.3 Pre-treatment of Oils and Fats Using Alkaline Neutralization
Neutralization of FFA in oils and fats can be carried out by the addition of
excess alkali; this method leads to the formation of soaps and to post reaction
separation problems (Suppalakpanya et al., 2008). This method can be used if
the FFA content in the oil was low. However, the cost of neutralization is low
due to lower chemicals used. Addition of more alkali may lead to the formation
of soap by saponification reaction; therefore the addition of alkali should be
limited. Neutralization of FFA content was used in the oil industries to reduce
the FFA content in the oil. The main disadvantage of using this method is its
deficiency to treat high FFA content oil. On the other hand, after the pre-
treatment of oils using this method, the excess alkaline catalyst will react with
triacylglycerols (TAG) in presence of methanol and consequently forms FAME
but in low concentration due to low dosage of alkaline catalyst or due to the
consumption of the catalyst during the pre-treatment process. High dosage of
alkaline catalyst will lead to form soap therefore catalyst dosage optimization is
very crucial during pre-treatment process.
2.6.4 Pre-treatment of oils and fats by heating (Drying)
Pre-treatment by heating is mainly done to reduce the water content and to
improve the settling of particles and impurities of WCO. Oils or fats with high
FFA content need heating in order to melt down and reduce its viscosity. Pre-
treatment of oils and fats by heating has many advantages in terms of cost
because of its simplicity and without using any expensive chemicals. Pre-
27
heating has been used for SPO and acidic crude palm oil because at room
temperature SPO usually exists in semisolid phase (Hayyan et al. 2010; 2011).
In case of used cooking oils (UCO) analysis showed that the differences
between UCO and virgin oil are not very substantial (Knothe, et al. 1997).
Therefore, in most cases, heating and removal by filtration of solid particles
suffices for subsequent transesterification (Enweremadu and Mbarawa, 2009).
However, in some cases the products of oil decomposition cause deterioration
in oil quality, which can lead to reduced ester yield during biodiesel production
and the formation of unwanted products. The negative effects of the undesirable
compounds can be avoided by the proper treatment of the UCO (Enweremadu
and Mbarawa, 2009).
Supple et al. (2002) used steam and sedimentation method to investigate the
effects of oil pre-treatment on the properties of UCO and the produced esters.
The study was carried out in two stages consisting of pretreatment and heating
of the oil at 65o C followed by sedimentation in both stages. The effects of
these treatments on the physical and chemical properties of UCO were studied.
Results after both stages of pretreatment showed that there was a reduction in
moisture content, free fatty acid and a substantial reduction in viscosity while
the calorific value increased. The pretreated UCO was transesterified with
methanol (6:1 molar ratio) using 1% KOH as the catalyst at 60o C. The
decrease in FFA (6.3–4.3%) and moisture content (1.4–0.4%), respectively
accounted for the substantial increase in ester yield (from 67.5% to 83.5%)
(Enweremadu and Mbarawa, 2009; Supple et al. 2002).
28
2.6.5 Pre-treatment of oils and fats by column chromatography
The effects of pretreatment of UCO on ester yield by column chromatography
were studied by Ki-Teak and Foglia (2002). Used cooking oil containing 10.6%
FFA and 0.2% water was purified by passing it through 50% aluminum oxide
stationary phase. The FFA and water contents decreased from 10.6% to 0.23%
and from 0.2% to 0.02 wt%, respectively. The conversion of untreated WCO
before column chromatography was observed to have increased from 25% after
24 h of reaction, to 96% when pretreated oil was used (Ki-Teak and Foglia,
2002; Enweremadu and Mbarawa, 2009). This method can be used in order to
extract carotenoides as by-products of pre-treatment process. Carotenoides are
widely used in food product and other applications.
2.6.6 Pre-treatment of oils and fats by glycerolysis
Castor oil with an acid value of 4.7 mg KOH/g was neutralized with crude
glycerol (Sousa et al., 2010). The method was used crude glycerol as by
product of transesterification of castor oil with methanol in presents of
potassium hydroxide as alkaline catalyst. Crude glycerol was applied for a
period of 1 and 2 h, reducing the acid value of the oil to 2.7 and 0.44,
respectively. The results confirmed that glycerol can be used to neutralize the
oil before its use in the production of biodiesel (Sousa et al., 2010). The crude
glycerol-rich process stream often comprises methanol (avolatile component),
water, residual catalyst and a small amount of fatty acid salts or soaps that were
present in the starting material or unintentionally produced in the
transesterification reaction. Then neutralization effect of crude glycerol is
mostly caused by saponification of free fatty acids with residues of base
29
catalyst that remain with the glycerol after its separation from the methyl esters.
FFA was converted into salts and soaps, which was miscible to the crude
glycerol-rich phase and leave the oil-rich phase. This proposed neutralization
step helps to reduce the acid value of the oil and also helps to remove traces of
catalyst from crude glycerol (Sousa et al., 2010). In case that if the glycerol has
been used in the process the recovery, reclaiming and reusing a residue of
alkaline catalyst which contains in the crude glycerol will be highly desirable
process because this process had used the cycling the waste materials in a
closed loop, therefore recycling process results in a reduction of the total cost of
biodiesel production in many steps such as handling, managing and disposal of
the waste. Figure 1 shows proposed industrial flowchart to produce biodiesel
using pretreatment of caster oil by its crude glycerol. However, the process is
suitable if FFA was low in the raw materials such as waste cooking oils but it is
not suitable if the raw materials have high FFA such as yellow and brown
grease from restaurant. However, Glycerolysis technique involves adding
glycerol to the raw material and heating it to high temperature (200oC), can be
done without catalyst or by adding catalyst such as zinc chloride. The glycerol
reacts with the FFA to form monoacylglycerol (MAG) and diacylglycerols
(DAG) (Gerpen et al., 2004). Figure 2 shows the rate of decrease of the fatty
acid level in a batch of animal fat. The conditions were 100 g animal fat, 13 g
glycerol, 0.1 g ZnCl, 200 oC, 11 psi vacuum.
2.6.7 Pre-treatment of Oils and Fats Using Ultrasonic Energy
Ultrasonic energy was used for the pretreatment of SPO for biodiesel
production Hayyan et al. (2009b). The study used ultrasonic energy in order to
30
investigate the effect of sonication time on the reduction of FFA in SPO. The
results showed that the conversion of FFA to FAME by applying ultrasonic
energy is related to length of sonication time. The FFA content of SPO was
reduced from 24.5% to less than 3% using molar ratio 10:1, reaction
temperature 50oC and 2% wt/wt sulfuric acid to SPO in 300 minutes sonication
time. Santos et al. (2010) have used ultrasound assisted pretreatment of Nile
tilapia oil (Oreochromis niloticus) to produce biodiesel. Nile tilapia oil is a low
cost feedstocks and generally contains high amounts of FFA. The reaction was
carried out by applying low-frequency high-intensity ultrasound (40 kHz) under
atmospheric pressure and ambient temperature. The hypothesis of using
ultrasonic waves in pretreatment of oils and fats and producing biodiesel was
ultrasonic irradiation causes cavitation of bubbles near the phase boundary
between the alcohol and oil phases. As a result, micro fine bubbles are formed.
The asymmetric collapse of the cavitation bubbles disrupts the phase boundary.
Impinging of the liquids creates micro jets leading to intensive mixing of the
system near the phase boundary. The cavitation may also lead to a localized
increase in temperature at the phase boundary enhancing the transesterification
reaction. Neither agitation nor heating are required to produce biodiesel by
ultrasound application because of the formation of micro jets and localized
temperature increase (Stavarache et al., 2005; Stavaracheet al., 2006).
2.6.8 Pre-treatment of oils and fats using microwave energy
The common heating system for biodiesel production uses heating coils to heat
the raw material. This method consumes high energy (Suppalakpanya et al.,
2008). Using microwave for preparative chemistry, it is possible to accelerate
31
the rate of reactions and selectivity (Mazzocchia, et al., 2002). Hence, it was
possible to prepare biodiesel rapidly and with good conversions by microwave
heating (Mazzocchia et al., 2002).
Hayyan et al.(2008) have used microwave in order to evaporate the water
content, melt and purify SPO from the particles and other impurities before
using a chemical reactor for the esterification reaction. Saifuddin and Chua
(2004) have used microwave in the pre-treatment of UCO. The study used
filtration and drying using microwave oven at 60o C for 10 min.
2.6.9 Pre-treatment of oils and fats using sequence (multi) methods
Cvengros and Cvengrova (2004) used a sequence of pre-treatment methods to
reduce the FFA, water, and polymer content in UCO before carrying out a two-
stage transesterification with KOH as catalyst at 65o
C for 90 min. FFA was
removed by neutralization with alkalis (KOH or NaOH) and removed as soaps
while high polymer content was treated with activated carbon and removed by
adsorption. Film vacuum evaporation was found to be more suitable for de-
acidification and drying. While drying was performed under moderate
conditions of 159oC and 20 mbar, de-acidification required more severe
conditions of 200–280o
C and 0.1–8 mbar. The reported yield of methyl ester
obtained from the treated oil was 96%.
Prior to transesterification of UCO using alkali catalyst, Issariyakul et al.
(2007) carried out pretreatment by centrifuge to remove solid portion of the oil.
Water was removed by mixing WCO with 10 wt% silica gel (28–200 mesh)
followed by stirring and vacuum filtration. Recently, in their study, Dias et al.
(2008) filtered UCO under vacuum after dehydration overnight using
32
anhydrous sulfate, and finally filtered again under vacuum prior to
transesterification. To produce biodiesel from used frying sunflower oil,
Predojevic (2008) pretreated the oil by drying over calcium chloride and
filtered through cellulose filter to remove any suspended matter and calcium
chloride crystals. Other pretreatment methods have been reported in the
literature like drying over magnesium sulfate and subsequent filtration under
vacuum to remove any suspended matter and magnesium crystals (Felizardo et
al., 2006).
2.6.10 Degumming and Dewaxing of crude oils
The purpose of degumming and dewaxing is to remove fat-soluble impurities in
the oil. Dewaxing is especially required for RBO because of its high content of
wax esters (Pandey, 2009). Degumming is usually done by adding polar
solvents to the oil under adequate mixing to allow polar lipids to be extracted
into the polar phase. The mixture is then cooled and centrifuged whereby wet
gum is removed with the water phase. Water degumming is the preferred
method if minimal loss of bioactive compounds is desired. It was found that a
processing temperature of about 70°C and an addition of 4% water (based on
the oil weight) was enough to substantially remove the gums (Indira et al.
2000). A novel degumming process employed the use of 1% (v/w) CaCl2
solution, which achieved simultaneous degumming and dewaxing (Rajam et al.
2005).
33
2.7 Pre-treatment Processes of Crude Biodiesel
2.7.1 Pre-treatment of Crude Biodiesel Using Microwave
The addition of extra glycerol to the reaction mixture was found to be helpful in
glycerol separation (Encinar et al., 2007). Suppalakpanya et al. (2009) have
added pure glycerol at the end of the transesterification reaction before the
separation of crude biodiesel than crude glycerol by gravitation. This resulted in
the formation of an upper phase consisting of FAEE, and a lower phase
containing glycerol. The addition of 2–6 wt% of pure glycerin did not decrease
the glycerol content, because the pure glycerol dissolved in the FAEE, and
could not induce a separation reaction. Addition of more than 6 wt% of pure
glycerol greatly decreased the glycerol content due to separation from the
FAEE. The optimum amount of pure glycerol was found to be 10 wt%. When
pure glycerol was added in dosages more than 10 wt%, no significant effect
was observed on the glycerol content of FAEE. However, Encinar et al. (2007)
have added 25% of pure glycerol due to the different chemical and physical
properties of crude biodiesel used and some differences in the process used.
Excess ethanol in FAEE phase was evaporated by heating at 80oC, followed by
standing in a separatory funnel 30 min. Separation of glycerol decreased the
glycerol content in FAEE. The study of Suppalakpanya et al. (2009) found that
the glycerol content in FAEE before adding pure glycerol, after adding the
optimum amount of pure glycerol, and after evaporation of ethanol was 5.49,
1.47 and 0.21 wt%, respectively.
34
2.7.2 Pre-treatment of Crude Biodiesel Using Acid Neutralization
Crude biodiesel enters a neutralization step and then passes through an alcohol
stripper before the purification by washing step. In some cases, acid is added to
crude biodiesel to neutralize any remaining catalyst and to split any soap. Soaps
react with the acid to form water soluble salts and free fatty acids. Gerpen et al.,
(2004) stated that neutralization before the washing step reduces the materials
required for the washing step and minimizes the potential for emulsions being
formed during the washing step.
2.7.3 Pre-treatment of Crude Biodiesel Using Rotary Evaporator and
Distillation
The reaction was captured by immersing the mixture in an ice bath. The excess
of methanol was recovered under vacuum (10 ± 1 mm Hg) at 50 oC with a
rotational evaporator. Then, the mixture was centrifuged at 2000 rpm for 10
min and the mixture was separated into two layers. The upper layer contained
the FAME (crude biodiesel) with lighter color, and the lower layer was the
glycerol and catalyst. After separating the two layers, the methyl esters were
treated with activated carbon to dehydrate and discolor the product. The
glycerol layer was distilled and kept for reuse. The catalyst at the bottom of the
reactor was decanted. It could easily be separated and reused without any
further treatment. Biodiesel yield was calculated relative to the initial amount of
yellow horn oil by weight. At the end of the transesterification process, pure
glycerin (0–20 wt% of glycerin/oil) was added, and the resulting mixture was
heated in the microwave oven at 70W for 1 min. This resulted in the formation
of an upper phase consisting of ethyl esters and a lower phase containing
35
glycerin. After separation of the layers by sedimentation in a separator funnel,
excess ethanol in the ethylester phase was evaporated by heating at 80oC, and
then purified with bleaching earth (0–1.4 wt% of bleaching earth/oil), mixed for
5 min and separated by centrifuge. The residue of ethyl ester in spent bleaching
earth was extracted using hexane. The collected hexane was then evaporated at
80oC. Unreacted alcohol should be removed with distillation equipment before
the washing step to prevent excess alcohol from entering the wastewater
effluent.
2.8 Factors Affecting the Pre-Treatment Process
The acid esterification process is a typical method of producing biodiesel from
high FFA oil (Canakci and Van Genpen, 1999; 2001). Many studies revealed
that the biodiesel could be produced successfully from oil and fats containing
high FFA by two step process, acid-catalyzed esterification followed by the
alkali catalyzed transesterification. The first step converts the FFA in oil and
fats to FAME and results in the reduction of FFA level. The triacylglycerols
(TAG) in this low FFA pretreated oil are then converted to FAME in the second
step. Esterification followed by transesterification was recommended and
conducted by many studies in order to obtain high yield and quality of biodiesel
(Wang, et al., 2006; Canakci and Van Genpen, 2001; Naik et al., 2008;
Nakpong and Wootthikanokkhan, 2010). However, in order to obtain high yield
with high quality and purity, the process parameters should be investigated to
maximize the yield of biodiesel and minimize the cost of production. The most
important variables that effect both esterification and transesterification
processes are:
36
• Type of catalyst
• Methanol: Oil Molar Ratio
• Reaction temperature
• Reaction time and stirrer speed
2.8.1 Effect of Catalyst Type
The catalysts used in biodiesel production are generally classified into two
Main categories, acidic and alkaline. The most commonly preferred acidic
catalysts for the esterification process are sulfuric, hydrochloric , sulphonic and
PTSA acids. For the transesterification process, sodium hydroxide (NaOH),
sodium methoxide and potassium hydroxide (KOH) are preferred as alkaline
catalysts (Canakci, 2007). The cheapest and the best known homogeneous acid
catalyst used for the esterification reaction is H2SO4. A survey of the literature
revealed that a wide variety of heterogeneous base and acid catalysts are under
investigation. The most tested feedstock is waste cooking oil or synthetic acidic
feedstocks, and less the side stream refining products. The most frequently
cited heterogeneous catalysts are the strongly acidic sulfonated ion exchange
resins, zeolites, mixed metal oxide, mesostructured silicas and mesoporous
carbon. The use of biocatalysts (lipases) has also been reported (Jian-Xun et al.,
2007). One of the main disadvantages associated with biocatalysts use, is the
high price compared to chemical catalyst. A non-catalytic biodiesel production
route with supercritical methanol has also been developed (Demirbas, 2009).
Unlike the alkali-catalyzed method, the presence of water positively affected
the formation of methyl esters. However, the high excess of methanol, which
has to be used in supercritical conditions, makes the process economically
unfavorable. Sulfuric acid and KOH was used in esterification and
37
transesterification processes respectively in many studies. Coconut oil
containing 12.8% FFA was used as a feedstock to produce biodiesel by a two-
step process. In the first step, FFA level of the coconut oil was reduced to 0.6%
by esterification using sulfuric acid. In the second step, TAG in the product
from the first step were transesterified with methanol by using potassium
hydroxide (KOH) to produce methyl esters and glycerol. In the first step, the
FFA content in coconut oil was reduced from the initial value of 12.8 to 0.6%
by acid-catalyzed esterification. The optimum condition of this step was
methanol to oil ratio of 0.35 v/v, acid catalyst concentration of 0.7% v/v of oil,
reaction temperature of 60oC, and reaction time of 60 min. After that, the 0.6%
FFA oil was transesterified with methanol using an alkaline catalyst. The
optimum condition for this step was methanol-to-oil ratio of 0.4 v/v, KOH
catalyst concentration of 1.5% w/v of oil, reaction temperature of 60oC, and
reaction time of 60 min. The methyl ester content of the coconut biodiesel
product was achieved at 98.4% w (Nakpong et al., 2010). It was reported by Di
serio et al., (2008) that using 6.40×10-5
mol of PTSA as acid catalyst can
decrease the FFA content in soybean oil from 20.5% to 1.1% and the yield of
biodiesel after reaction obtained was only 48%. The reaction condition was
12:1 molar ratio, 180oC temperature, and 60 min reaction time. Wang, et al.,
(2006) conducted a comparison of two different processes to produce biodiesel
from waste cooking oil. In the first process biodiesel was prepared by sulfuric
acid, whereas the second process involved a two-step catalyzed processes in
which ferric sulfate –catalyst was used to convert FFA to FAME by an
esterification reaction and then an alkali catalyst was used in transesterification
reaction. The study concluded that the conversion of FFA of WCO into FAME
38
in the two-steps method was 97.22% at a reaction time of 4 hours, molar ration
10:1, while the conversion of acid catalyzed process was 90% at a reaction time
of 10 hours, molar ratio 20:1. Hence ferric sulfate showed much higher
catalytic activity compared to the acid catalyzed method. It was reported that
sulfuric acid is the most common acid catalyzed used in esterification because
of its low cost and availability (Canakci and Van Genpen, 2001). Naik et al.,
(2008) proposed Karanja oil as a new source for biodiesel production. The
study used sulfuric acid as a catalyst to treat the Karanja oil which has up to
20% FFA, 0.5% of sulfuric acid has reduced FFA content from 20% to less than
2% within 1 hour and 6:1 molar ratio methanol to FFA of Karanja oil. In
another study, Bhatti, et al., (2008) used waste tallow as low cost sustainable
potential feed stock for biodiesel production. The process was acid catalyzed
esterfication using sulfuric acid followed by base catalyzed transesterification
using potassium hydroxide. The optimal conditions for processing 5g of tallow
were: reaction temperature of 50 and 60oC; molar ratio oil/methanol of 1:30 and
1:30, amount of sulfuric acid 1.25 and 2.5 g for chicken and mutton tallow,
respectively. Under optimal conditions, chicken and mutton fat methyl esters
formation of 99.01% and 93.21% respectively were obtained after 24 hours in
the presence of sulfuric acid.
2.8.2 Effect of Molar Ratio
Methanol to Oil ratio is one of the important factors that affect the conversion
of FFA to FAME, as well as the overall production cost of biodiesel. The acid
catalyst process needs extra methanol than that needed by the transesterification
process. However, in practice, the molar ratio should be higher than that of the
stoichiometric ratio in order to drive the reaction towards completion
39
(Ramadhas, et al., 2004). Canakci and Van Gerpan, (1999; 2001) advocated the
use of large excess quantity of methanol (15:1-35:1) while using the sulfuric
acid as catalyst. Di Serio et al., (2008) have used 12:1 molar ratio to decrease
the FFA content in soybean oil from 20.5% to 1.1% using PTSA as acid
catalyst. (Chongkhong et al., 2007) have used 8:1 molar ratio methanol to palm
fatty acid distillate with 1.834 wt% of sulfuric acid at 70°C under its own
pressure with a retention time of 60 minutes. A study by Veljkovic et al., (2006)
used tobacco seed oil as an alternative raw material to produce biodiesel. The
results showed that the FFA content was reduced from 17 wt% to less than 2
wt% using a pretreatment step followed by alkali transesterification reaction.
The conditions of pretreatment were; a molar ratio of 18:1 of methanol to oil,
60 °C reaction temperature, at 25 minutes. For the case of waste cooking oil
catalyzed by sulfuric acid, biodiesel production increased rapidly within 1-6
hours and then dropped down, and when the molar ratio of methanol to oil
exceeded 16, waste cooking oil conversion increased rapidly, in addition waste
cooking oil conversion increased with the amount of sulfuric acid up to 4 wt%
(Wang, et al., 2006). Increasing the molar ratio of the methanol to oil increases
the rate of formation of the methyl esters. The reaction was faster with a high
molar, whereas longer reaction time was required for the lower molar ratio to
get the same conversion (Pandey, 2009).
2.8.3Effect of Reaction Temperature
The reaction temperature reported by most studies during different steps ranges
between 45-65oC. Increasing the reaction temperature up to the boiling point of
the methanol increases the rate of methyl ester formation. However, the same
yield can be achieved at room temperature by simply extending the reaction
40
time (Freedman et al., 1984). A reaction temperature above the boiling point of
the alcohol is avoided because at high temperature, it tends to accelerate the
saponification of the glycerides by the alkaline catalyst before completion of
the alcoholysis (Dorado et al. 2004). A study by Leung and Guo (2006) showed
that a temperature higher than 50oC has a negative impact on the product yield
for neat oil, but a positive effect for waste oil with higher viscosities. However,
The FFA of WCO were esterified with methanol catalyzed by ferric sulfate in
the first step, and the TG in WCO were transesterified with methanol catalyzed
by potassium hydroxide in the second step. The results showed that ferric
sulfate had high activity to catalyze the esterification of FFA with methanol.
The conversion rate of FFA reached 97.22% when 2 wt% of ferric sulfate was
added to the reaction system containing molar ratio of 10:1 composition and
reacted at 95oC for 4 h. The methanol was vacuum evaporated, and
transesterification of the remained TG was performed at 65oC for 1 h in a
reaction system containing 1 wt% of KOH and 6:1 mole ratio of methanol to
TG. The final product consisted of 97.02% biodiesel. Using heterogeneous
catalysts such as ferric acid necessitates high temperature compared to
homogenous acid catalysts. On the other hand, there are other merits of using
ferric acid heterogeneous catalyst such as its high efficiency, no acidic waste
water, low equipment cost and easy recovery of the catalyst. A two-step
technique combining pre-esterification catalyzed by cation exchange resin with
transesterification catalyzed by base alkali was developed to produce biodiesel
from rapeseed oil deodorizer distillate. The FFA in the rapeseed oil deodorizer
distillate was converted to FAME in the pre-esterification step using a column
reactor packed with cation exchange resin. The acid value of oil was reduced
41
from the initial 97.60 mg-KOH/g oil to 1.12 mgKOH/g oil under the conditions
of cation exchange resin D002 catalyst packed dosage of 18 wt%, oil to
methanol molar ratio 1:9, reaction temperature 60 °C, and reaction time 4 h.
The biodiesel yield by transesterification was 97.4% in 1.5 h using 0.8 wt%
KOH as catalyst and a molar ratio of oil to methanol 1:4 at 60°C. The
properties of rapeseed oil deodorizer distillate biodiesel production in a packed
column reactor followed by KOH catalyzed transesterification were measured
up the standards of EN14214 and ASTM6751-03.
2.8.4 Effect of Reaction Time
In order to achieve perfect mass transfer between the reagents and SPO during
esterification reaction, it must be stirred well at constant rate and sufficient
contact time. It was reported elsewhere that using 12 wt% methanol in oil at 70o
C, the acid value of oil was reduced from 14 mg-KOH/g oil to below 1 mg-
KOH/g-oil in 2 hr using 1% wt sulfuric acid. The conversion of FFA to FAME
was 97% using 4 wt% solid acid (Lu, et al., 2009). A study by Veljkovic et al.
(2006) showed that esterification reduced the FFA level from about 35% to less
than 2% in 25 and 50 minutes with molar ratios of 18:1 and 13:1, respectively.
Biodiesel production from a high content of FFA waste cooking oil catalyzed
by sulfuric acid increased rapidly within 1-6 hours and then dropped down, and
when the molar ratio of methanol to oil exceeded 16, waste cooking oil
conversion increased rapidly. In addition waste cooking oil conversion
increased with the amount of sulfuric acid up to 4 wt% (Wang, et al., 2006). It
was reported that using rice bran with high FFA content (approximately 75%),
the FAME content only increased from 80% in 30 min to about 87% in 5 h.
42
Adding more acid or methanol did not significantly affected the methyl esters
content (Pandey, 2009). Production of FAME from palm fatty acid distillate
(PFAD) having high free fatty acids (FFA) was investigated by chongkhong et
al., (2007). The optimum condition for the continuous esterification process
was a molar ratio of methanol to PFAD at 8:1 with 1.834wt% of sulfuric acid at
70oC under its own pressure with a retention time of 60 min. The amount of
FFA was reduced from 93 wt% to less than 2 wt% at the end of the
esterification process. The FAME was purified by neutralization with 3M
sodium hydroxide in water solution at a reaction temperature of 80oC for 15
min followed by transesterification process with 0.396M sodium hydroxide in
methanol solution at a reaction temperature of 65oC for 15 min.
2.8.5 Effect of Stirrer Speed
In order to achieve perfect mass transfer between the reagents and oils during
the esterification pre-treatment step and the transesterification process,
continuous mixing at sufficient reaction time has noticeable effect on the degree
and rate of reaction completion. Mixing is very important in triglyceride
transesterification, as oils or fats are immiscible with alcoholic methanol
solution. Once the two phases are mixed by stirring and the reaction is started,
stirring is no longer needed (Ma et al., 1999; Pandey 2009). The mixing effect
is more significant during the slow rate region of the esterification and
transesterification reaction and when the single phase is established, mixing
becomes insignificant. Understanding the mixing effects on the kinetics of the
reaction process is a valuable tool in the process scale-up and design. After
adding the methanol and catalyst to the oil, stirring for 5 to 10 minutes
promotes a higher rate of conversion. This fact can be seen when the reaction
43
starts after adding the regents and operating the reactor mixer (Demirbas,
2009). A pre-treatment study of waste rapeseed oil with high FFA using 400
rpm has been conducted by Yuan, et al., (2008). Sahoo et al., (2007) have
carried out experiments to produce biodiesel from polanga seed oil with 450
rpm continuous stirring using a mechanical stirrer speed of 450 rpm. Al-
Widyan and Al-Shyoukh, (2002) produced biodiesel from waste palm oil by
efficient boiling of the reactants. Lifka and Ondruschka, (2004) compared
different methods of mixing using (magnetic stirrer, ultrasound and ultra turrax)
using PTSA as a catalyst. The study found that ultrasonic mixing was the
lowest in energy consumption.
2.9 Effect of the Pre-Treatment Process on the Transesterification
Reaction
The problem with substituting triacylglycerine for diesel fuel is mostly
associated with high viscosity, low volatility and polyunsaturated characters all
of these undesired properties can cause severe operational problems. During
esterification process, FFA and very small amount of triacylglycerols are
converted to FAME in the presence of acid catalyst. The remaining
triacylglycerols are then converted to FAME by transesterification process
using alkaline catalyst (Hayyan et al., 2010b). The remaining FFA in treated
SPO after esterification process was neutralized by alkaline catalyst during
transesterification process. SPO which was treated by esterification process in
optimum conditions was further transesterified under conditions. However
Common method to produce biodiesel was used homogeneous base catalyst,
44
such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) (Felizardo et
al., 2006, Kulkarni and Dalai, 2006; Lam et al., 2010).
2.10 Quality Control and the Limits of Pre-Treatment Process
There are no such international standard to qualify the pre-treatment process of
oils and fats. However, for pre-treatment of oils and fats there are limits of
physical and chemical properties and mainly FFA content is the most important
factor to qualify the pre-treatment process and its controlling conditions. The
properties of biodiesel fuel vary depending on their origins. Previous studies on
high FFA content oils (of different feed-stocks), revealed that, oil should not
contain more than 1% FFA to be suitable for use in an alkaline catalyzed
transesterification reaction (Freedman and pryde, 1982; Liu, 1994; Canakci and
Van Gerpen, 1999; Canakci and Van Gerpen, 2003; Lu et al., 2009).
Consequently, a prerequisite for any pre-treatment process is its ability to
achieve this FFA threshold.
2.11 Recent Development of Acidic Catlaysts and their Challenges
The key point in conducting efficient biodiesel production reactions is the
catalytic activity of the used catalyst. Hence, catalyst development gains high
attention by the scientific and industrial communities. The studies in this field
target improving the economy and production quality and throughput that can
be applied in an industrial scale. Besides, an economical catalyst with
environmental merits will be more industrially recommended in order to fulfill
the green applied energy goals. Biocatalysts such as lipase, was widely used for
biodiesel preparation (Atadashi et al., 2010; Chattopadhyay et al., 2011). The
high cost of the enzyme is the main problem for its commercial utilization as a
biocatalyst in chemical reactions. Different types of acidic solid catalysts were
45
applied in the pre-treatment of acidic oils such as acid exchange resins (Tesset
et al., 2010), ferric sulfate (Zhang et al., 2012; Montefrio et al., 2010) and
carbon nano tube based solid acid catalysts (Shu et al., 2009; Shu et al., 2010).
Recently, ligninderived carbonaceous catalyst (LCC) was used to reduce the
FFA content in acidic soybean soapstock for biodiesel production (Guo et al.,
2012). The reaction time for the esterification reaction using LCC was too long
compared to the corresponding homogenous catalyst. In addition, LCC needs
special equipment and conditions for the catalyst preparation. The common
acidic catalysts used for the esterification reaction are p-toluenesulfonic acid
(PTSA) (Di Serio et al., 2008), trifluoromethanesulfonic acid (Hashim et al.,
2011), sulfuric acid (Hayyan et al., 2011a) and methanesulfonic acid (Aranda et
al., 2008). These types of acids are readily commercially available and can be
used directly in the synthesis of materials and chemical reactions. The common
industrial catalyst for the esterification reaction is sulfuric acid (Haas et al.,
2003; Atadashi, 2012). The main obstacle for using homogeneous catalyst in
the biodiesel production is the separation of catalyst and purification of product.
Thus, recycling of homogeneous catalysts is one of the main reasons for losing
the catalyst in chemical reactions. Recently ionic liquids (ILs) and their
applications have triggered the interest of researchers in many fields (Olivier-
Bourbigou et al., 2010). ILs have applied successfully in versatile biological,
chemical, and electrochemical applications (Yue et al., 2011; Xue et al., 2006;
Hayyan et al., 2012). ILs have many advantages for the industrial use including
their undetectable vapor pressure and liquidity at a wide temperature range
(Xue et al., 2006; Naushad et al., 2012). ILs are usually expensive and
unavailable at industrial scale. Deep eutectic solvents (DESs) are categorized as
46
a cheap class of ILs (Abbott et al., 2003; Abbott 2008). DESs share many
merits and physical properties with ILs (Abbott 2008). In addition, the DES
preparation is very simple compared to conventional ILs (Cooper et al., 2004).
Choline chloride (ChCl) is the common salt used as the main ingredient in a
wide range of available DESs. The ChCl-urea based DES was one of the first
reported in literature, and was used later in many applications (Kareem et al.,
2010; Zhang et al., 2012). ChCl-based DESs were also used in
electrodeposition of zinc–tin alloys (Abbott et al., 2007), synthesis of
polyoxometalate based hybrids (Wang et al., 2010) and preparation of zeolite
(Cooper et al., 2004). A metal halide-based DES was made of ChCl.xZnCl2 and
introduced as a catalyst in the transesterification reaction (Long et al., 2010).
De Santi et al (2012) used quaternary ammonium methanesulfonate salts based
DES for esterification of carboxylic acids. Few studies reported the use of DES
with palm oil; examples are the removal of alkaline transesterification catalyst
and the separation of glycerol from biodiesel (Shahbaz et al., 2011). DESs
continging PTSA and ammoimum or phosphonium salts have not been
investigated as a reaction solvent and as a catalyst for the practical FFA
reduction in industrial acidic oils, such as ACPO. Although PTSA has been
used as a catalyst in esterification reactions, its hygroscopic nature and storage
and its handling difficulties have prevented its commercial usage (Di Serio et al
2008). Conversion of solid organic acids such as PTSA into DES using simple
technique will provide opportunity to improve a wide range of catalysts in
esterification and a host of other chemical reactions.
47
7. Summery and Remarks
Developing a pre-treatment process of oils and fats before conducting the
transesterification reaction is very essential to produce biodiesel within the
international standard specifications of biodiesel fuel. Selection of raw material,
economic pre-treatment and production processes in biodiesel industry should
be done carefully before applying the production technology. Studying the
chemical and physical properties has very great contribution in the selection of
proper pre-treatment processes. The current study concludes that any method of
pre-treatment can be used in biodiesel industry. Moreover, the cost of the pre-
treatment process and the process efficiency have a crucial role in biodiesel
production especially if the production is in pilot or full plant scale. The merits
and the cost of each process must be studied before the selection of a pre-
treatment process. This study reviewed pre-treatment technologies which have
successful impact on the large scale biodiesel production. New development in
pre-treatment technologies are still essential for improving product quality and
reducing production cost.
48
3 CHAPTER III
Experimental Methodology
3.1 ASPO Sample Collection and Preparation
ACPO sample was obtained from West Oil Mill, Carey Island, Selangor,
Malaysia. ACPO was preheated because it usually exists in semisolid phase
under ambient conditions The SPO was melted in an oven at 80oC. Melting
process also helped to evaporate the water and settled the impurities in ACPO.
In this study ACPO with different FFA content was used for pretreatment
process.
3.2 Materials
The studied salts and acids were purchased from different suppliers as listed in
Table 3.1 and 3.1. The structures of salts and PTSA are shown in Scheme 3.1.
Table 3.1: Name, Formula and Mwt of Acids used in this study
Acid name Formula Mwt
(g/mol)
Toluene-4-sulfonic acid monohydrate
(Water content : 8-13%)
C7H8O3S.H2O
190.22
Benzenesulfonic acid (Water content : <
2%)
(Sulfuric acid : < 1%)
C6H5SO3H 158.17
Methanesulfonic acid CH4O3S 96.11
Ethanesulfonic acid C2H6O3S 110.13
Trifluoromethanesulfonic acid CHF3O3S 150.08
Chromosulfuric acid
Synonyms: Dichromate-sulfuric acid
mixture
H2SO4 > 92,
CrO3 > 1.3
-
49
Table 0.2: Name, formula and Mwt of salts used in this study
Salt name Formula Mwt(g/mol) M.P
°C
Choline Chloride
(2-hydroxyethyl-
trimethylammonium)
C5H14ClNO 139.62 302
N,N-
Diethylethanolammonium
chloride
C6H16ClNO 153.65 133 -
136
Methyltriphenylphosphonium
bromide
C19H18BrP 357.22 230 -
233
Benzyltriphenylphosphonium
chloride
C25H22ClP 388.87
337
Allyltriphenylphosphonium
bromide
C21H20BrP 383.26
222 -
225
50
Scheme 0.1: Structures of PTSA, ammonium and phosphonium salts used in
this study
51
3.3 Chemical Analytical Analysis (published in Bioresource Technology
2011)
The ACPO FFA content after each experiment was determined according to the
American Oil Chemist’s Society (AOCS) official method Ca 5a-40 commercial
fats and oils (AOCS, 1997). Characteristics of ACPO were determined
according to MPOB test methods (Kuntom et al., 2005). The fatty acid
composition of ACPO was determined using GC/MS (Agilent Technologies
7890A gas chromatograph equipped with 5975C mass spectrometer), with a
capillary column DB-wax 122-7032. Ester content, mono-, diand
triacylglycerols (TAG), free and total glycerol content were determined using
GC/FID (Perkin Elmer Clarus 500).
3.4 Synthesis of ChCl-DES
Choline chloride salt and PTSA were dried at 60°C under vacuum, and then
mixed in a molar ratio of 1:3 salt to PTSA. A glass jacketed vessel with a
mechanical stirrer was used to prepare DES at a temperature of 60-70°C and a
stirrer rate of 350 rpm for 3 hours mixing time. The final mixture of DES
formed a viscous liquid at room temperature. The preparation was carried out
using isolated fume hood.
3.5 Synthesis of Biodiesel from ACPO
Acidic crude palm oil exists as a semisolid phase at room temperature which
leads to difficulties in the transferring, handling and to slow down the reaction.
Consequently, ACPO was heated at 70oC in the oven. Methanol was added to
the pre-heated ACPO and mixed for 5–10 min. In order to increase the
homogeneity among reactants, acid catalyst was added to the reactor after a
52
period of 30 min from reaction startup time. The FFA content of the treated
ACPO was measured and reported for all experiments. Biodiesel was produced
from ACPO via two catalyzed reactions (esterification and transesterification).
In the pre-treatment stage, the ACPO sample weight for each experiment was
500 gm. While in the second reaction potassium hydroxide (KOH) was used as
a catalyst in order to convert the triacylglycerols (TAG) to fatty acid methyl
ester (FAME). The product of the esterification reaction is considered as a raw
material for the transesterification reaction. Following transesterification
reaction, gravity separation and evaporation of excess methanol were
performed. The product was then treated by water washing to remove the
impurities, free glycerol, soap and residuals of alkaline catalyst. Validation
experiments were conducted several times in order to investigate the optimum
conditions of ACPO pre-treatment process. In the second stage, 1% wt KOH
was dissolved in methanol (10:1 M ratio) and then the mixture was added to the
pre-treated ACPO in the transesterification reactor after a period of 30 min
from reaction startup. Recyclability of acid catalyst was examined via
separating the spent catalyst and reusing it to treat ACPO for further
consecutive runs. The last stage of this study was the characterization of the
produced biodiesel using the EN 14214 and ASTM D6751 international
biodiesel standards. All experimental runs were performed in a lab scale batch
multiunit reactor system with methanol reflex. The reaction temperature and
mixing intensity were monitored and controlled using specially designed
feedback controllers. Figure 3.1 shows the flow chart of biodiesel production
from ACPO.
53
Figure 3.1: Flow chart of biodiesel production from ACPO
ESTERFICATION
Acid
Catalyzed
Potassium
Methoxide
TRANSESTERIFICATION
EVAPORATION
WASHING PROCESS
Crude Biodiesel
PURE BIODIESEL
Collection of ACPO after heating at 60oC
ES
TE
RIF
ICA
TIO
N
PR
OC
ES
Alcohol
TR
AN
SE
ST
ER
IFIC
AT
ION
PR
OC
ES
PU
RIF
ICA
TIO
N P
RO
CE
S
SETTLING PHASES Crude
Glycerol
54
4 CHAPTER IV
RESULTS AND DISCUSSIONS
4.1 Characteristics of ACPO
4.1.1 Physical properties of ACPO
Investigating feedstock characteristics during the early stage of research is a crucial
requirement for any industrial application. In this work ESA was used as sulfonic
acid based catalyst in the esterification reaction. The pre-treatment of high content
oils and fats by esterification reaction was proposed in different studies (Liu, 1994;
Canakci and Van Gerpen, 2001; Naik et al., 2008; Hayyan et al., 2010b). Pre-
treatment of acidic oils or fats before biodiesel production is considered as an
essential stage especially if the raw materials are of high FFA content (Ma and
Hanna, 1999; Canakci and Van Gerpen, 2001; Demirbas, 2009). Thus, an acid
catalyzed pre-treatment step by esterification reaction to convert the FFA to FAME
followed by transesterification reaction using alkali–catalyzed offers an effective
and efficient method to convert high FFA feedstock to biodiesel fuel (Canakci and
Van Gerpen, 2003). The physicochemical properties of various oils as products or
by-products of industrial palm oil mills vary in accordance with many factors such
as the milling process conditions, the location from which oil was produced (within
the mill), water content, storage time, technical problems during milling etc.
Sludge palm oil (SPO) was previously studied as a possible raw material for
biodiesel production (Hayyan et al., 2010b; 2011). The physicochemical properties
of SPO are very close to that of ACPO because both oils share the same origin
from industrial mills with different FFA content. ACPO and SPO have lower
55
quality compared to crude palm oil in terms of FFA, moisture and other
contaminants contents. Table 1 shows the similarities and differences between SPO
and ACPO. Generally, industrial mill byproducts such as SPO and ACPO are
traded based on FFA, moisture and impurities contents (Lin, 1989). Due to its
lower specifications, ACPO has less cost per ton than that of CPO. Table 1 shows
that the peroxide value of ACPO is higher than that of SPO. While the FFA
content in ACPO lies between that of SPO and CPO which indicates that ACPO
ranks after CPO and before SPO in terms of quality. ACPO and SPO are of lower
quality compared to CPO in terms of FFA, moisture and other contaminants
contents. The FFA content of ACPO in this study was 8.8% while the
corresponding CPO value was below 5% (Tan et al., 2009). An oil with FFA
content higher than 15% is considered as SPO (Lin, 1989). The water content in
SPO and ACPO was higher than that of CPO. Based on the saponification value of
ACPO, the calculated average molecular weight was 827 which was used in the
molar ratio calculation. ACPO has low grade characterization parameters such as
FFA, peroxide value and moisture content due to long storage conditions. Products
and byproducts of industrial palm oil mills such as CPO and SPO are generally
traded based on FFA, moisture and impurities contents (Lin, 1989). Table1 shows
a comparison of properties between SPO and ACPO. It is clear that ACPO has the
highest FFA content and poor quality indicators which highlight the importance of
a reliable pretreatment stage in its processing. Accordingly, an acid-based
esterification is needed prior to the main transesterification stage. Pretreatment of
acidic oils and fats via esterification reaction was proposed in different previous
studies (Canakci and Van Gerpen, 2001; Naik et al., 2008; Hayyan et al., 2010b;
56
Hayyan et al., 2011). Pretreatment of oils or fats before biodiesel production is
considered an important industrial stage especially if the raw materials have high
FFA content (Canakci and Van Gerpen, 2001). Thus, an acid catalyzed
pretreatment step by esterification reaction to convert the FFA to FAME followed
by a transesterification reaction using alkali–catalyst offers an effective method to
convert high FFA feedstock to biodiesel fuel (Canakci and Van Gerpen, 2001).
Table 4.1Characteristics of ACPO
Parameters SPO* ACPO
Free fatty acid, FFA (%) 22.33±0.77 8.6± 0.40 Peroxide value (ml mol/kg) 1.52± 0.40 7.45 ± 0.55 Moisture content (%) 1.20± 0.06 1.105±0.2 Iodine value, IV 53.4± 0.71 56± 0.52 Impurities (%) 0.05± 0.007 0.056±0.006 Saponification value (mg KOH/g oil) 190± 1.41 197.00 ± 1.70 Unsaponification matter (%) 1.47± 0.26 6.70± 0.26 Ash (%) 0.015± 0.001 0.011± 0.001 Anisidine Value (AV) - 3.3± 0.052 Acid value (mg KOH/mg) 48.88± 1.70 17.02± 0.5 DOBI (Index) 0.55±0.03 1.80± 0.033
*Hayyan et al., (2010b)
4.1.2 Fatty Acid Composition of ACPO
The fatty acid composition of ACPO plays an essential role in qualifying the
structure of oils and fats. Table 2 shows the fatty acid composition of ACPO. The
principal fatty acids are: oleic, palmitic, linoleic and stearic acid. Saturated fatty
acids in ACPO were 50.23 wt% while unsaturated fatty acids were 49.70 wt%. The
composition of saturated and unsaturated fatty acids obtained in this work were
slightly different compared to those reported by Elsheikh et al., (2011). According
to the results obtained by Hayyan et al., (2010b), saturated fatty acids in SPO were
57
47.17 wt% while the unsaturated fatty acids were 50.83 wt%. The chemical
compositions of fatty acids from various products and by-products of industrial
mills are very similar in many aspects.
FFA content of ACPO increased proportionally with storage time. It was observed
that FFA content of ACPO increased at room temperature by an amount of 1% after
6 months storage time. There are many other factors that affect the degree of oils
decomposition and increase the FFA content such as water content of oil, storage
time, environment and temperature of the storage place also the type of container
can effect if the container isolated or it was opened to air for long time etc. Solar
energy increases the oxidation reaction of oil and eventually decreases the quality
of oil. Storage time has a significant effect on the increase of high FFA content of
ACPO. ACPO exists in a semisolid or solid form at room temperature (27± 2oC)
due to the availability of saturated fatty acids and the high content of FFA
compared to CPO or refined palm oil. Therefore, ACPO has higher pour and cloud
points as compared to crude palm oil low FFA content. Consequently, ACPO
should be preheated before proceeding to the pretreatment stage using the
esterification reaction. On the other hand, higher saturated fatty acids in oils give a
higher cetane number and make the oil less prone to oxidation (Canakci and Van
Gerpen, 2001).
58
Table 4.2 Fatty acid composition of ACPO
Fatty
acids
Structure Type of
fatty acid
Fatty
acids
wt%
Lauric acid C12:0 Saturated 0.284+
Myristic
acid
C14:0 Saturated 1.00+
0.04 Palmitic
acid
C16:0 Saturated 44.8+
1.95 Palmitoleic C16:1 Unsaturated 0.30+
0.01 Stearic
acid
C18:0 Saturated 3.80+
0.8 Oleic acid C18:1 Unsaturated 39.90+
1.70 Linoleic
acid
C18:2 Unsaturated 9.28+
1.0 Alpha-
Linolenic
C18:3 Unsaturated 0.22+
0.03 Arachidic C20:0 Saturated 0.35+
4.3 Screening of Different Types of Acids
4.3.1 Effect of ESA Catalyst
4.3.2 4.2.1.1 Effect of ESA Dosage
Catalyst dosage plays a very important role during the esterification reaction.
Finding the optimum dosage of catalyst has the priority among all reaction
parameters due to its effectiveness to the whole process. Figure 4.1 shows the
effect of ESA dosages on reducing of FFA content in ACPO, conversion of FFA to
FAME and yield of treated ACPO. The FFA content was reduced from 8.6% to less
than 1% in the ranges of 0.75–3.5 wt%. Low ESA dosage such as 0.25 and 0.5 was
insufficient to decrease FFA content to less than 1%. It has been reported in Figure
1 that using 0.25% (ESA to ACPO) the FFA content was 2.22% while using 0.5%
the FFA content was 1.3%. Dosage at 0.5% was very close the limit and slightly
higher than 1% FFA content. According to study by Hayyan., et al., (2010b; 2011)
and Ramadhas et al., (2005) were noted that the FFA content below 2% can be
59
used for biodiesel production via alkaline transesterification. In order to enhance
the reaction and to increase the efficiency of pretreatment process 0.75% of ESA
was more recommended in this study for industrial application. ESA excessive
dosage did not show any improvement in ACPO FFA content reduction. TAG was
analyzed after esterification using ESA and it was found that 3-7% of TAG was
converted to FAME. According to Figure 1 there was no significant improvement
in the yield of treated ACPO. However treated ESA was slightly fluctuated within
the range of 92-96%. Using 0.75% of ESA reduced the FFA content from 8.6% to
0.43%. The ACPO yield was 96.68% while the conversion of FFA to FAME was
94.98%. ESA has same activity compared to other sulfonic-based acids such as
PTSA and therefore it can easily reduce the FFA content of oils. The reduction
achieved using ACPO is more than the corresponding reduction in SPO due to the
higher initial FFA content in the former. Another study by Di serio et al., (2008)
reported that using PTSA at 6.4x10-5
mol can reduce the high FFA content soybean
oil from 20.5% to 1.1%. However, the obtained yield of treated soybean after
esterification reaction was very low (48% only).
60
Figure 4.1 Effect of ESA dosages on FFA content reduction, conversion of FFA to
FAME and yield of treated ACPO
4.2.1.2 Effect of Molar Ratio
Methanol one is of the essential reactant in the pretreatment process via
esterification reaction. Molar ratio is significantly affecting the conversion of FFA
to FAME during the course of reaction. In economical point of view, controlling
the molar ratio results in the reduction of the overall production cost of biodiesel.
In this study molar ratio was studied in the range (1:1-20:1). Figure 4.2 shows the
effect of molar ration on the reduction of high FFA content in ACPO, conversion of
FFA to FAME and yield of treated ACPO. Low loading of methanol makes the
reaction insufficient to decrease FFA content to the target FFA level. According to
Figure 4.2, reduction of FFA content using molar ratio at 1:1 and 5:1 were 5.66%
and 2.32% respectively. It is mentioned that the stoichiometry of the esterification
reaction a molar ratio of 1:1 is needed in order to drive the reaction towards
0
20
40
60
80
100
120
0
2
4
6
8
10
0 0.5 1 1.5 2 2.5 3 3.5 4
Yie
ld%
& C
on
ve
rsio
n%
FF
A%
Dosage of ESA wt%
FFA%
Limits of FFA%
Yield% of ACPO
Conv. of FFA to FAME
61
completion (Demirbas, 2009; Park et al., 2010). On the other hand, results of this
study showed that 1:1 molar ration was very low amount to reduce the FFA content
to 1%. Practically, the molar ratio of esterification reaction should be much higher
than 5:1. Hence, further molar ratios were studied in order to select the optimum
molar ratio and to satisfy the pretreatment economically. The FFA content was
decreased from 8.6% to less than 1% in the range of 10:1- 20:1. Molar ratio at 10:1
was sufficient to decrease the high FFA content in ACPO from 8.6% to 0.56%.
Excess molar ratio did not show any improvement in the reduction of FFA content.
Therefore, 10:1 was selected as optimum molar ratio for esterification reaction
using ESA catalyst. Yield of treated ACPO was 96% while the conversion of FFA
to FAME was 93.47%. Hayyan et al., (2010b: 2011) was used 10:1 also as
optimum condition to teat SPO for biodiesel production.
Figure 4.2 Effect of molar ratio on FFA content reduction, conversion of FFA to
FAME and yield of treated ACPO
0
20
40
60
80
100
120
0
2
4
6
8
10
0 2 4 6 8 10 12 14 16 18 20 22
Yie
ld%
& C
on
vers
ion
%
FF
A%
Molar Ratio
FFA% Limits of FFA%
Yield% of treated ACPO Conv.% of FFA to FAME
62
4.2.1.3 Effect of Reaction Temperature
Biodiesel production reactors involve a highly complex set of chemical reactions
and heat transfer characteristics (Mjalli et al., 2009). Reaction temperature has
crucial effect and conceded as one of the important factors affecting the reduction
of FFA content in high oil acidity as well as in the conversion of FFA to FAME.
Due to high temperature, methanol tends to evaporate faster and finally the
reaction loses one of the important ingredients in esterification reaction. Moreover,
energy consumption for industrial scale production will increase with the increase
of reaction temperature and the total operating cost of process will be higher. In
this study reaction temperature was varied from 40oC to 70
oC. Figure 4.3 shows
the effect of the reaction temperature on the reduction of high FFA content in
ACPO, conversion of FFA to FAME and yield of treated ACPO. Low reaction
temperature such as 40oC was not sufficient enough to reduce the FFA content in
ACPO. While the FFA content using 50oC reaction temperature was exactly 1%.
The recommended FFA content for transesterification was less than 1%. Higher
reaction temperature such as 70oC showed significant reduction of FFA content and
slightly lower FFA content compared to that of 60oC. In order to save the energy of
pretreatment process to the minimum level, 70oC was eliminated. Hence, 60
oC was
selected as optimum reaction temperature for pretreatment of ACPO using ESA.
Reaction temperature at 60oC was achieved successfully FFA content 0.5%, 98%
yield of treated ACPO and 94.14% conversion of FFA to FAME. Optimum reaction
temperature in this study was within the range (45 – 65oC) of the reaction
temperatures maintained by most researchers (Sharma et al. 2008).
63
Figure 4.3 Effect of temperature on FFA content reduction, conversion of FFA to
FAME and yield of treated ACPO
4.2.1.4 Effect of Reaction Time
Chemically, reaction time one of the most important and essentially operating
conditions in all reactions. This study was examined the reaction time at 3-120
minutes. Figure 4.4 presents the effect of the reaction time on the reduction of high
FFA content in ACPO, conversion of FFA to FAME and yield of treated ACPO.
Based on the results it was investigated that ESA has high catalytic activity due the
rapid reduction in FFA content at first 10 minutes. Demirbas, (2009) was
mentioned that after adding reactant to the oil, stirring for 5–10 min promotes a
higher rate of conversion. The reduction in FFA content at 10 and 15 minutes were
2.4% and 1.4% respectively. FFA content at 30 minutes was 0.43% which is below
the limit of FFA content for transesterification reaction. There was no significant
improvement at long reaction time higher than 30 minutes as shown in Figure 4.
Therefore, 30 minutes was selected as optimum reaction time for esterification
0
20
40
60
80
100
120
0
2
4
6
8
10
0 10 20 30 40 50 60 70 80 90
Yie
ld%
& c
on
ve
rsio
n%
FFA
%
Temperature oC
FFA% Limits of FFA%
Yield% of treated ACPO Conv.% of FFA to FAME
64
reaction. Conversion of FFA to FAME was 94.9% while the yield was 95%.
Reaction time at 30 minutes was achieved successfully FFA content 0.5%, 98%
yield of treated ACPO and 94.14% conversion of FFA to FAME. According to
Hayyan et al., (2010b) used sludge palm oil with 22.33% and the time of
pretreatment process was 60 minutes while in this study the reaction time required
to treat the high FFA content in ACPO was 15-30 minutes. Therefore, it can be
estimated simple correlation between FFA content and reaction time which is every
1% FFA content equal 2.5-3.5 minutes. However, this correlation is approximately
can give an idea about the reaction time because there are other conditions can
affect the reaction time such as the quality of oils and the oil source.
Figure 4.4 Effect of reaction time on FFA content reduction, conversion of FFA to
FAME and yield of treated ACPO
4.2.1.5 Validation of Optimal Esterification Conditions
The Optimum conditions for esterification reaction using ESA were found to be
0.75% (wt/wt) dosage of ESA to ACPO, 10:1 molar ratio, 60oC temperature and
0
20
40
60
80
100
120
0
2
4
6
8
10
0 30 60 90 120 150
Yie
ld%
& C
on
ve
rsio
n%
FFA
%
Reaction Time min
FFA%
Limits of FFA%
Yield% of treated ACPO
conv.% of FFA to FAME
65
30 minutes reaction time. Using these optimum conditions the FFA was reduced
from 8.6% to 0.8%, with 96% yield of treated ACPO and 90.7% conversion of FFA
to FAME.
4.3.3 Effect of MSA Catalyst (published in Chemical Papers 2011)
4.3.3.1 Effect of MSA Dosage
The catalyst dosage is an essential factor with an important role in the reaction and
the total production cost. Fig. 4.5 shows the effect of the MSA dosage on reducing
acidity in the ACPO, conversion of FFAs to FAMEs and the corresponding yield of
the treated ACPO. The oils or fats should have an acid value of no more than 1 mg
KOH g−1
which is equivalent to approximately 0.5 % FFA content (Ma & Hanna,
1999; Sharma et al., 2008; Demirbas, 2009). All materials or chemicals or fatty
acid sources for biodiesel production should be substantially anhydrous (Ma &
Hanna, 1999). Use of a small dosage of MSA has a large effect on reducing the
acidity of the ACPO. Acid dosages of 0.25 % and 0.5 % were insufficient to
reduce the acid value to the target limit for the transesterification reaction. A
dosage of 0.75 % resulted in an acid value reduction to the limit of the acceptable
value, while 1 % showed more catalytic activity. Higher MSA dosages did not
contribute to the reduction of oil acidity and might increase the cost of the pre-
treatment process due to extra and unnecessary catalyst use. Hence, a 1 % MSA
catalyst dosage was selected as the optimum operating value for the esterification
reaction. The yield of the treated ACPO did not change with varying MSA
dosages. However, the yield of the treated ACPO attained a maximum of 96 %.
Triacylglycerols (TAGs) were measured using a GC-FID after the pre-treatment
66
reaction with MSA. It was found that 2−6.5 % of TAGs contained in the ACPO
were converted to FAMEs. Accordingly, conversion to FAMEs reduced the
reaction time in the second reaction (transesterification).
Fig 4.5 Effect of MSA dosages on acid value reduction and yield of treated ACPO
at 10 : 1 molar ratio, 60 °C reaction temperature, 60 min reaction time, and 400
rpm stirrer speed. (●) − Acid value, (-) − limit of acidity, (▲) − yield of treated
ACPO.
4.2.2.2 Effect of the Methanol to ACPO Molar Ratio
In the course of the esterification reaction, the methanol to ACPO molar ratio
significantly affects the FFA conversion to FAMEs. In addition, from a cost
perspective, the molar ratio affects the total cost of biodiesel production. Fig. 4.6
shows the effect of molar ratio on the reduction of acidity and yield of the treated
ACPO after the pre-treatment process. The molar ratio was examined within a
range of from 4 : 1 to 20 : 1 (methanol to the ACPO). The yield of the treated
ACPO was almost constant at different molar ratios and there was no significant
0
5
10
15
20
0 1 2 3 4
Dosage of MSA /%
Acid
valu
e /(m
g g
−1)
0
30
60
90
120
Yie
ld /%
67
improvement, as shown in Fig. 4.6. It was observed that a small loading of
methanol below 8 : 1 could reduce the acidity to above the limit of the
transesterification reaction. A value of 8 : 1 was sufficient to attain the target acid
value (1.0 mg KOH g−1
). Acid values at higher molar ratios fluctuated slightly
below 1 mg KOH g−1. A molar ratio of 20 : 1 (methanol to ACPO) resulted in the
lowest acid value reported, which was (0.3 mg KOH g−1). The problem associated
with high molar ratios is the high energy cost entailed in evaporating the excess
methanol, as well as the cost of the methanol. Therefore, the 8 : 1 molar ratio was
selected as the optimum ratio in order to support the reaction with sufficient
methanol and to conserve energy.
Fig. 4.6 Effect of molar ratio on acid value reduction and yield of treated ACPO at
1 % dosage of MSA to ACPO, 60 °C reaction temperature, 60 min reaction time,
and 400 rpm stirrer speed. (●) − Acid value, (-) − limit of acidity, (▲) − yield of
treated ACPO.
4.2.2.3Effect of Reaction Temperature
Most studies have maintained the reaction temperatures range of 45−65 °C
(Sharma et al., 2008; Hayyan et al., 2011b). Therefore, the experiments in this
0
5
10
15
20
0 4 8 12 16 20
Molar ratio
Acid
valu
e /(m
g g
−1)
0
30
60
90
120
Yie
ld /%
68
study were monitored in a range of from 40 °C to 80 °C. Fig. 4.7 shows that a
higher temperature strongly affects the reduction of the acidity in the ACPO, while
there is no significant effect on the yield of the treated ACPO. It is known that the
temperature enhances the esterification reaction and, in most studies, the use of
higher temperatures, around 50 °C or 60 °C has been suggested for homogeneous
acid-catalysed pre-treatment processes (Chongkhong et al., 2007; Hayyan et al.,
2010a, 2011b). Lower temperatures of 40 °C or 50 °C showed low acidity
reduction, while temperatures of from 60 °C to 70 °C showed a significant
reduction in the acid value of the ACPO (18 mg KOH g−1
to less than 1.0 mg KOH
g−1
). The higher reaction temperature of 70 °C was regarded as the optimum but
required a significant amount of energy. Therefore, 60 °C was selected as the
optimum for esterification of the ACPO. In recent studies, ionic liquids were used
as a new class of catalysts in which higher reaction temperatures of 160 °C or 170
°C were reported (Han et al., 2009; Elsheikh et al., 2011). This indicates that, in
terms of energy requirements, sulphonic-based acid catalysts perform much better
than ionic liquids.
69
Fig. 4.7 Effect of reaction temperature on acid value reduction and yield of treated
ACPO at 1 % dosage of MSA to ACPO, 8 : 1 molar ratio, 60 min reaction time,
and 400 rpm stirrer speed. (●) − Acid value, (-) − limit of acidity, (▲) − yield of
treated ACPO.
4.2.2.4 Effect of Reaction Time
In order to reach steady state conditions with a complete esterification reaction,
adequate reaction time must be allowed (Hayyan et al., 2011a). Reaction time was
varied within a range of from 3 min to 150 min to determine the optimum
conditions. Fig. 4.8 presents the effect of the reaction time on the reduction of
acidity and yield of the treated ACPO. Over the first 10 min, most of the acidity
was reduced, and the reduction was (5.0 mg KOH g−1
). The rapid reduction reflects
the catalytic activity of the sulphonic group in MSA. Fig. 4.8 shows that the acid
value decreased significantly with the increase in reaction time. Half an hour was
sufficient to reduce the acid value to less than 1.0 mg KOH g−1
.. Hence, 30 min
0
5
10
15
20
0 30 60 90
Temperature /°C
Ac
id v
alu
e /
(mg
g−
1)
0
30
60
90
120
Yie
ld /
%
70
was selected as the optimum reaction time for pre-treatment of the ACPO using
MSA.
Many studies have reported one hour as the optimum reaction time for the
esterification reaction (Chongkhong et al., 2007; Di Serio et al., 2008; Hayyan et
al., 2010a, 2011a). This study reports half that period (30 min) of reaction in order
to obtain a high yield and acidity reduction in comparison with previous studies.
However, the reaction time is affected by the level of the FFAs content, which is
responsible for the acidity of oils.
Fig. 4.8 Effect of reaction time on acid value reduction and yield of treated ACPO
at 1 % dosage of MSA to ACPO, 8 : 1 molar ratio, 60 °C reaction temperature, and
400 rpm stirrer speed. (●) − Acid value, (-) − limit of acidity, (▲) − yield of
treated ACPO.
4.2.2.5Validation of Optimum Esterification Conditions
The optimum conditions of the esterification reaction using the MSA catalyst were
1 % dosage of the MSA catalyst to the ACPO, a molar ratio (methanol to the
0
5
10
15
20
0 40 80 120 160
Reaction time /min
Acid
valu
e /(m
g g
−1)
0
30
60
90
120
Yie
ld /%
71
ACPO) of 8 : 1, the temperature of 60 °C and the 30 min reaction time. Using these
optimum conditions, the acidity was reduced from 18 mg KOH g−1 to slightly
below the acceptable limit with a yield of the treated ACPO of 93−98 %.
4.2.3 Effect of CSA Catalyst (Accepted in Bulgarian Chemical Communications
2012)
4.2.3.1 Effect of CSA dosage
Using a fixed reaction time (30 min) and fixed molar ratio (10:1), the dosage of
CSA was varied in the range of 0.25- 3.5 wt%. The results showed that CSA was a
very effective catalyst in the esterification reaction. Figure 4.9 shows the effect of
different dosage of CSA on the reduction of FFA content, conversion of FFA to
FAME and yield of treated LGCPO. A FFA content of less than 1% was achieved
using a CSA dosage of more than 1 wt%. To minimize catalyst usage, a catalyst
dosage value of 0.75% was selected as optimum dosage to reduce the FFA content
to the acceptable limit. The conversion of FFAs to fatty acid methyl ester (FAME)
was 86.77% after the esterification process. The FFA content of LGCPO was
reduced from 7.0% to 0.92%. In a similar work on SPO, it was reported that 0.75
wt% of the catalyst (such as PTSA) was the optimum dosage needed to reduce the
high FFA content.
Figure
4.2.3.2 Effect of molar ratio
Molar ratio is one of the important factors affecting the conversion of FFA to
FAME, as well as the overall production cost of biodiesel. In this study, the molar
ratio of methanol to
describes the effect of molar ratio on the reduction of FFA content, conversion of
FFA to FAME and yield of treated LGCPO. No significant change observed in the
reduction of FFA within the molar ratio range of 10:1 to 20:1. On the other hand, a
minimum of
from 7.0 % to below than 1%, which is the limit of FFA for a successful
transesterification reaction. In order to save methanol consumption, a molar ratio
of 10:1 was sufficient for the est
optimum ratio reported for the esterification of SPO
72
Figure 4.9 Effect of CSA dosages on FFA content reduction, conversion of
FFA to FAME and yield of treated LGCPO
Effect of molar ratio
Molar ratio is one of the important factors affecting the conversion of FFA to
FAME, as well as the overall production cost of biodiesel. In this study, the molar
ratio of methanol to LGCPO was varied between 2:1 and 20:1. Fig
describes the effect of molar ratio on the reduction of FFA content, conversion of
FFA to FAME and yield of treated LGCPO. No significant change observed in the
reduction of FFA within the molar ratio range of 10:1 to 20:1. On the other hand, a
minimum of 10:1 molar ratio were required to reduce the FFA content of LGCPO
from 7.0 % to below than 1%, which is the limit of FFA for a successful
transesterification reaction. In order to save methanol consumption, a molar ratio
of 10:1 was sufficient for the esterification reaction. This ratio was also the
optimum ratio reported for the esterification of SPO using PTSA as acid catalyst
Effect of CSA dosages on FFA content reduction, conversion of
FFA to FAME and yield of treated LGCPO
Molar ratio is one of the important factors affecting the conversion of FFA to
FAME, as well as the overall production cost of biodiesel. In this study, the molar
LGCPO was varied between 2:1 and 20:1. Figure 4.10
describes the effect of molar ratio on the reduction of FFA content, conversion of
FFA to FAME and yield of treated LGCPO. No significant change observed in the
reduction of FFA within the molar ratio range of 10:1 to 20:1. On the other hand, a
10:1 molar ratio were required to reduce the FFA content of LGCPO
from 7.0 % to below than 1%, which is the limit of FFA for a successful
transesterification reaction. In order to save methanol consumption, a molar ratio
erification reaction. This ratio was also the
using PTSA as acid catalyst.
Figure 4.10
4.2.3.3 Effect of
The reaction
40 - 70oC. Figure 4
of FFAs content of LGCPO. In this study, it was fou
temperature to reduce the FFA content in LGCPO was 60
the FFAs content was reduced from 7.0 % to below 1%, with a very high
conversion of FFA to FAME. Therefore, a reaction temperature of 60
selected for the esterification of LGCPO.
73
Effect of molar ratio on FFA content reduction, conversion of FFA to
FAME and yield of treated LGCPO
Effect of Reaction Temperature
The reaction temperature during the different steps was reported to range between
C. Figure 4.11 presents the effect of reaction temperature on the reduction
of FFAs content of LGCPO. In this study, it was found that the lowest reaction
temperature to reduce the FFA content in LGCPO was 60
the FFAs content was reduced from 7.0 % to below 1%, with a very high
conversion of FFA to FAME. Therefore, a reaction temperature of 60
for the esterification of LGCPO.
Effect of molar ratio on FFA content reduction, conversion of FFA to
FAME and yield of treated LGCPO
temperature during the different steps was reported to range between
presents the effect of reaction temperature on the reduction
nd that the lowest reaction
temperature to reduce the FFA content in LGCPO was 60oC. At this temperature
the FFAs content was reduced from 7.0 % to below 1%, with a very high
conversion of FFA to FAME. Therefore, a reaction temperature of 60oC was
Figure 4.11
4.2.3.4 Effect of
In order to determine the optimum reaction time, esterification reaction time was
varied in the range (3
time on the reduction of FFA content, conversion of FFA to FAME and yield of
treated LGCPO.
most of FFA was removed as shown in Figure 5. The fast reduction reflects the
catalytic activity of
significantly with the increase in re
sufficient to reduce the FFA content to less than 1%. It was found that after 30
74
11 Effect of reaction temperature on FFA content reduction, conversion
of FFA to FAME and yield of treated LGCPO
Effect of Reaction Time
In order to determine the optimum reaction time, esterification reaction time was
varied in the range (3-150 minutes). Figure 4.12 shows the effect of the reaction
time on the reduction of FFA content, conversion of FFA to FAME and yield of
treated LGCPO. During the course of the reaction and at the first 10
most of FFA was removed as shown in Figure 5. The fast reduction reflects the
catalytic activity of CSA. As shown in Figure 5, the FFA content decreased
significantly with the increase in reaction time. A bout 30 to 60 min was
sufficient to reduce the FFA content to less than 1%. It was found that after 30
Effect of reaction temperature on FFA content reduction, conversion
of FFA to FAME and yield of treated LGCPO
In order to determine the optimum reaction time, esterification reaction time was
shows the effect of the reaction
time on the reduction of FFA content, conversion of FFA to FAME and yield of
During the course of the reaction and at the first 10-20 minutes,
most of FFA was removed as shown in Figure 5. The fast reduction reflects the
. As shown in Figure 5, the FFA content decreased
action time. A bout 30 to 60 min was
sufficient to reduce the FFA content to less than 1%. It was found that after 30
min there was no improvement in the reduction of the acidity along reaction time.
Hence, in order to optimize the reaction time, 30 minute
shortest reaction time for the pre
can be considered as the optimum value due to the additional cost entailed with
longer reaction time.
Figure 4.12
4.2.3.4 Validation of
This study concludes that LGCPO is a suitable feedstock for biodiesel production
with a pre-treatment stage using
LGCPO) with 10:1 molar ratio and
Using these conditions the FFA content was reduced from 7.0 % to less than 1%.
The yield of biodiesel was 85% with 0.14 % FFA and ester
mol−1
).
75
min there was no improvement in the reduction of the acidity along reaction time.
Hence, in order to optimize the reaction time, 30 minute
shortest reaction time for the pre-treatment of LGCPO. The shortest reaction time
can be considered as the optimum value due to the additional cost entailed with
longer reaction time.
12 Effect of reaction time on FFA content reduction, conversion of FFA
to FAME and yield of treated LGCPO
Validation of Optimum Esterification Conditions
concludes that LGCPO is a suitable feedstock for biodiesel production
treatment stage using CSA as a catalyst at 0.75% wt/wt (catalyst to
LGCPO) with 10:1 molar ratio and 60o
C at 30 min and 200 rpm as stirrer speed.
sing these conditions the FFA content was reduced from 7.0 % to less than 1%.
The yield of biodiesel was 85% with 0.14 % FFA and ester
min there was no improvement in the reduction of the acidity along reaction time.
Hence, in order to optimize the reaction time, 30 minutes was selected as the
treatment of LGCPO. The shortest reaction time
can be considered as the optimum value due to the additional cost entailed with
ent reduction, conversion of FFA
to FAME and yield of treated LGCPO
onditions
concludes that LGCPO is a suitable feedstock for biodiesel production
as a catalyst at 0.75% wt/wt (catalyst to
C at 30 min and 200 rpm as stirrer speed.
sing these conditions the FFA content was reduced from 7.0 % to less than 1%.
The yield of biodiesel was 85% with 0.14 % FFA and ester content 97.5% (mol
76
4.2.4 Effect of BZSA in the Reduction of FFA in ACPO (Accepted In
International J of Green Energy)
4.2.4.1 Effect of BZSA catalyst
The BZSA catalyst was varied in order to achieve low FFA reduction. The FFA
content was set to the industrial standard level of 1%. Figure 4.13 shows the influence
of BZSA at different concentrations on the reduction of FFA in LGCPO and yield of
treated LGCPO. Initially, the FFA content was 9.3% and after esterification the FFA
was reduced to less than 1% within the catalyst dosage range of 0.75–3.5 wt%. FFA
content after esterification reaction was high when the BZSA loading was low due to
insufficient catalyst dosage. High FFA content in the treated oil would not be
favorable for biodiesel production. When the used catalyst dosage was set to 0.25%
and 0.5% the residual FFA content was reduced to 1.82% and 1.52% respectively.
Dosage in excess to 0.75% showed no noticeable improvement in terms of FFA. Low
catalyst strength might not be sufficient to treat the oil due to the low catalytic activity
of BZSA relative to high FFA during the course of esterification reaction. Based on
the treated LGCPO, a 0.75 wt/wt% (BZSA to LGCPO) resulted in 0.90% FFA content,
LGCPO yield of 97% and FAME conversion of 92.4%. It was reported that using
0.75% (PTSA) can reduced the FFA in SPO from 22.33% to less than 2% only with
the optimum conditions of 10:1 molar ratio, 60oC temperature of reaction, and 60
minutes reaction time (Hayyan et al., 2010a). There is a correspondence in the BZSA
dosage in the present study and that of the previous study using PTSA. However, the
chemical structure of BZSA resembles the simplest aromatic sulfonic acids used for
the pre-treatment of LGCPO in esterification reaction. Treated LGCPO was analyzed
77
using. GC-MS in order to investigate the conversion of triacylglycerols to fatty acid
methyl ester using BZSA. The FAME conversion was less than 10% at 1 hour
reaction time. This result give conclusion that BZSA is suitable catalyst for
esterification while in trasesterification it shows low catalytic activity. Therefore,
BZSA in the esterification followed by potassium hydroxide in the
trasesterification will be perfect method to save the time to produce high quality
biodiesel.
Figure 4.13. Effect of BZSA dosage on the FFA reduction and yield of treated
LGCPO
4.2.4.2 Molar Ratio Effect
Molar ratio was varied from 4:1 to 20:1. Figure 4.14 presents the molar ratio effect on
the FFA content reduction in LGCPO and the treated LGCPO yield. According to
Figure 4.14 the treated LGCPO yield was slightly increased with increasing molar
ratio from 4:1 to 6:1 with no significant enhancement after 6:1. The FFA content was
reduced when 4:1 molar ratio was used in the esterification reaction and the FFA
0
2
4
6
8
10
0 0.5 1 1.5 2 2.5 3 3.5 4Dosage of BZSA wt%
FF
A%
0
20
40
60
80
100
120
Yie
ld%
FFA%
Limits of FFA%
Yield% of treated LGCPO
78
reduction was from 9.3% to 2.4%. As mentioned earlier, the FFA target in this study is
1%, therefore, the ratio of 4:1 did not achieve this target. The FFA content using a
molar ratio of 6:1 was 1.93% which is still slightly higher than the recommended FFA
limit in this study. Figure 4.14 shows that there is no significant improvement in the
reaction by increasing the molar ratio from 8:1 to 20:1. The economy of the process is
highly affected by using higher reactants molar ratio. Hence, in order to save energy
the optimum ratio of methanol to LGCPO was selected to be 8:1 which reduced the
FFA content from 9.3% to 0.6% which is below the targeted FFA content. The FAME
conversion was 92.8% and the yield of treated LGCPO was 96%. Based on the study
of Hayyan et al., (Hayyan et al., 2011a) and the findings of this study, lower loading of
methanol can be used effectively to reduce the high acidity of oils such as SPO and
LGCPO.
Figure 4.14 Effect of molar ratio on the FFA reduction and the yield of treated LGCPO at
0.75 % dosage of BZSA to LGCPO, 60oC reaction temperature, 60 min reaction time, and
300 min-1
stirrer speed.
0
2
4
6
8
10
0 2 4 6 8 10 12 14 16 18 20 22
Molar Ratio
FF
A%
0
20
40
60
80
100
120
Yie
ld%
FFA% Limits of FFA% Yield% of treated LGCPO
79
4.2.4.3 Reaction Temperature Effect
In this study, the reaction temperature was varied within a wide range in order to
achieve the optimum conditions for biodiesel production. The temperature range
studied was from 40°C to 80°C. The results showed that the FFA content decreased
gradually from lower to higher temperatures. As indicated from Figure 4.15 there was
no significant effect on FFA reduction at high temperatures. On the other hand, a high
reaction temperature of 70-80oC is not recommended since it will be difficult to control
the reaction at these operating conditions. However, a suitable reaction temperature
must be provided. An FFA conversion to FAME of 3% and 1.5% were achieved for
the temperatures 40°C and 50°C respectively. The reaction at these temperatures is
slow with little enhancement in reaction yield. At these low temperatures, the reaction
did not proceed to completion. The FFA content in treated LGCPO at 60°C was 0.5%
which is lower than that achieved at lower temperatures and achieving the targeted
FFA as illustrated in Figure 4.15. In addition, sufficient reaction temperature such as
60°C will shorten the reaction time, saves the energy and consequently decreases the
production cost. At 60°C, a high yield of treated LGCPO (96%) was obtained, with a
2% FFA reduction and a 90.93% FAME conversion.
80
Figure 4.15 Effect of reaction temperature on the FFA reduction and the yield of treated
LGCPO at 0.75 % dosage of BZSA to LGCPO, 8:1 molar ratio, 60 min reaction time, and
300 min−1
stirrer speed.
4.2.4.4 Reaction Time Effect
Reaction time was varied from 3-150 minutes. The influence is presented in Figure
4.16 which shows the FFA reduction and the yield of treated LGCPO at different
reaction times. As can be seen from Figure 4.16, the treated LGCPO yield was slightly
increased when the reaction time was increased. At the reaction time of 15 minutes,
the FFA reduction was 1.4%, which is higher than the limits of transesterification
reaction, while the FFA content at 30-150 minutes was less than 1% FFA. In order to
decrease the cost of the pre-treatment process, 30 minutes of reaction time is sufficient
0
2
4
6
8
10
0 10 20 30 40 50 60 70 80 90
Temperature oC
FF
A%
0
20
40
60
80
100
120
Yie
ld%
FFA% Limits of FFA% Yield% of treated LGCPO
81
to reduce the FFA from 9.3% to less than 1%. Yield of treated LGCPO at these
conditions was 96% with a 90.93% FAME conversion.
Fig. 4.16 Effect of reaction time on the FFA reduction and yield of treated LGCPO at 0.75
% dosage of BZSA to LGCPO, 8: 1 molar ratio, 60oC reaction temperature, and 300 min−1
stirrer speed.
4.2.4.5 Validation of Optimum Conditions
The optimum esterification conditions using BZSA were 0.75% (wt/wt) BZSA to
LGCPO, 8:1 molar ratio, 60oC temperature, and 30 minutes reaction time. These
optimum conditions in this study achieved a treated LGCPO with 0.91% FFA content,
96% yield and 90.35% FAME conversion. The properties of final product after
transesterification and purification of biodiesel was 88.67% with 0.07% FFA and 95%
ester content.
0
20
40
60
80
100
120
0
2
4
6
8
10
0 30 60 90 120 150
Yie
ld%
FF
A%
Reaction Time min
FFA%
Limits of FFA%
Yield% of treated LGCPO
82
4.2.4 Effect of PTSA in the Reduction of FFA in ACPO (Presented in 2nd International
Conferences on Process Engineering and Advanced Materials 2012)
4.2.4.1 Effect of PTSA Dosage Catalyst dosage was varied in order to achieve low FFA content reduction, high
yield of treated oil and high conversion of FFA to FAME. In this study, the FFA
content was set to the recommended minimum FFA content level of 1%. Figure
4.17 shows the effect of different dosages of PTSA on the reduction of FFA
content in LGCPO and the corresponding yield of treated LGCPO. The dosage of
PTSA to LGCPO ranged from (0.25-3.5 wt/wt %). The results showed that PTSA
is a very active catalyst in the pre-treatment of LGCPO via esterification reaction.
The dosages values of 0.25 and 0.5 wt% PTSA to LGCPO attained a lower
reduction of the FFA in LGCPO. The high FFA content in LGCPO after reaction
exceeded the target limit because the PTSA loading was low and the catalytic
activity was insufficient to enhance the pre-treatment reaction. The targeted FFA
content for the transesterification reaction was below 1% and the results of this
study showed that the PTSA catalyst has the ability to achieve this limit at a
catalyst dosage of 0.75%. The FFA content was reduced in LGCPO significantly
from 9.5% to less than 1% using 0.75% up to 3.5%. Figure 1 illustrates that there
was no further reduction of FFA content using a dosage higher than 0.75%.
Fig. 4.17 Effect of PTSA dosages on acid value reduction and yield of treated LGCPO
4.2.4.2 Effect of the methanol to LGCPO molar ratio
Methanol is one of the main reactants in the esterification reaction that affect the
conversion of FFA content to FAME. The es
methanol to complete the reaction. In this study the molar ratio of methanol to
LGCPO was v
ratio on the FFA content reduction in LGCPO and the yield
was found that the yield of treated LGCPO slightly increased when the molar ratio
was increased from 4:1 to 6:1, and no significant change was observed with higher
molar ratios (6:1
content of LGCPO from 9.5% to 2.0%, which is above the limit set for the FFA in
this study. Molar ratio of 8 : 1 was sufficient to attain the target FFA content.
While no significant changes in the molar ratio above 10:1 up to 20:1.
83
Effect of PTSA dosages on acid value reduction and yield of treated LGCPO
Effect of the methanol to LGCPO molar ratio
Methanol is one of the main reactants in the esterification reaction that affect the
conversion of FFA content to FAME. The esterification reaction needs sufficient
methanol to complete the reaction. In this study the molar ratio of methanol to
LGCPO was varied from 4:1 to 20:1. Figure 4.18 presents the effect of the molar
ratio on the FFA content reduction in LGCPO and the yield
was found that the yield of treated LGCPO slightly increased when the molar ratio
was increased from 4:1 to 6:1, and no significant change was observed with higher
molar ratios (6:1-20:1). The minimum molar ratio of 4:1 decreased the
content of LGCPO from 9.5% to 2.0%, which is above the limit set for the FFA in
this study. Molar ratio of 8 : 1 was sufficient to attain the target FFA content.
While no significant changes in the molar ratio above 10:1 up to 20:1.
Effect of PTSA dosages on acid value reduction and yield of treated LGCPO
Methanol is one of the main reactants in the esterification reaction that affect the
terification reaction needs sufficient
methanol to complete the reaction. In this study the molar ratio of methanol to
presents the effect of the molar
ratio on the FFA content reduction in LGCPO and the yield of treated LGCPO. It
was found that the yield of treated LGCPO slightly increased when the molar ratio
was increased from 4:1 to 6:1, and no significant change was observed with higher
20:1). The minimum molar ratio of 4:1 decreased the FFA
content of LGCPO from 9.5% to 2.0%, which is above the limit set for the FFA in
this study. Molar ratio of 8 : 1 was sufficient to attain the target FFA content.
While no significant changes in the molar ratio above 10:1 up to 20:1.
Fig.4.18 Effect of molar ratio on FFA content reduction and yield of treated LGCPO
4.2.4.3 Effect of reaction temperature
In the current study, the reaction temperature was varied from 40°C to 80°C in
order to determine the optimum conditions for the p
4.19 shows the effect of the reaction temperature on the reduction of the FFA
content and yield of treated LGCPO. It was found that an optimum reaction
temperature of 60
from 9.5% to 0.30%, and the conversion of FFA to FAME was 96.7%. The yield
of treated LGCPO was 98% which is considered a high yield for biodiesel
production. With an increase in reaction temperature higher than 60
significant change in the y
temperature has many disadvantages such as high consumption of energy and the
loss of methanol due to the high degree of evaporation. Therefore it is not
recommended to use high reaction temperature in th
84
of molar ratio on FFA content reduction and yield of treated LGCPO
Effect of reaction temperature
In the current study, the reaction temperature was varied from 40°C to 80°C in
order to determine the optimum conditions for the pre-treatment reaction. Figure
shows the effect of the reaction temperature on the reduction of the FFA
content and yield of treated LGCPO. It was found that an optimum reaction
temperature of 60oC is needed. At this temperature, the FFA content was de
from 9.5% to 0.30%, and the conversion of FFA to FAME was 96.7%. The yield
of treated LGCPO was 98% which is considered a high yield for biodiesel
production. With an increase in reaction temperature higher than 60
significant change in the yield of treated LGCPO was observed. Higher reaction
temperature has many disadvantages such as high consumption of energy and the
loss of methanol due to the high degree of evaporation. Therefore it is not
recommended to use high reaction temperature in the pre-
of molar ratio on FFA content reduction and yield of treated LGCPO
In the current study, the reaction temperature was varied from 40°C to 80°C in
treatment reaction. Figure
shows the effect of the reaction temperature on the reduction of the FFA
content and yield of treated LGCPO. It was found that an optimum reaction
C is needed. At this temperature, the FFA content was decreased
from 9.5% to 0.30%, and the conversion of FFA to FAME was 96.7%. The yield
of treated LGCPO was 98% which is considered a high yield for biodiesel
production. With an increase in reaction temperature higher than 60oC, no
ield of treated LGCPO was observed. Higher reaction
temperature has many disadvantages such as high consumption of energy and the
loss of methanol due to the high degree of evaporation. Therefore it is not
-treatment of LGCPO.
Fig. 4.19 Effect of reaction temperature on FFA reduction and yield of treated LGCPO
4.2.4.4 Effect of reaction time
The reaction time was varied in a wide range (3
It was observed that the reduction of FFA content increased with an increase in
reaction time. During the first 10 minutes of reaction, the FFA content was
decreased from 9.5% to 2.5. After 15 minutes of reaction, the FFA content was
1.40%, which is slig
transesterification reaction. On the other hand, less 1% FFA was achieved for 30
up to 120 minutes of reaction time. In order to optimize the cost of the
pretreatment reaction, 30 minutes of reaction time
completion of the esterification reaction.
It was found that after 60 minutes of LGCPO esterification reaction, 3
triacylglycerols were converted to FAME. Conversion of FFA and some of
triacylglycols to FAME during este
of the transesterification reaction. The final FFA content after 30 minutes was
85
Effect of reaction temperature on FFA reduction and yield of treated LGCPO
Effect of reaction time
The reaction time was varied in a wide range (3-150 min) as shown in Figure
It was observed that the reduction of FFA content increased with an increase in
reaction time. During the first 10 minutes of reaction, the FFA content was
decreased from 9.5% to 2.5. After 15 minutes of reaction, the FFA content was
1.40%, which is slightly higher than the limits of FFA for the alkaline
transesterification reaction. On the other hand, less 1% FFA was achieved for 30
up to 120 minutes of reaction time. In order to optimize the cost of the
pretreatment reaction, 30 minutes of reaction time is very suitable for the
completion of the esterification reaction.
It was found that after 60 minutes of LGCPO esterification reaction, 3
triacylglycerols were converted to FAME. Conversion of FFA and some of
triacylglycols to FAME during esterification results in decreasing the reaction time
of the transesterification reaction. The final FFA content after 30 minutes was
Effect of reaction temperature on FFA reduction and yield of treated LGCPO
150 min) as shown in Figure 4.20.
It was observed that the reduction of FFA content increased with an increase in
reaction time. During the first 10 minutes of reaction, the FFA content was
decreased from 9.5% to 2.5. After 15 minutes of reaction, the FFA content was
htly higher than the limits of FFA for the alkaline
transesterification reaction. On the other hand, less 1% FFA was achieved for 30
up to 120 minutes of reaction time. In order to optimize the cost of the
is very suitable for the
It was found that after 60 minutes of LGCPO esterification reaction, 3-6% of the
triacylglycerols were converted to FAME. Conversion of FFA and some of
rification results in decreasing the reaction time
of the transesterification reaction. The final FFA content after 30 minutes was
0.20%. This low FFA content promotes the potential of successful
transesterification reaction.
Fig. 4.20 Effect of reaction time on FFA content reduction and yield of treated LGCPO
4.2.4.5Validation of optimum esterification conditions
After optimizing the esterification reaction conditions it was found that the
optimum conditions for the pre
LGCPO, 8:1 molar ratio, 60
optimum conditions the FFA was reduced from 9.5% to 1%.
4.4 Conversion of Homogenoues Acids
4.4.1 PTSA
4.3.1.1 Esterification of LGCPO using P
Esterification reaction was carried out in order to achieve the acceptable industrial
limit of FFA content. The acid catalyst dosages, molar ratio, reaction temperature,
reaction time and mixing intensity are th
esterification reaction. Figure
86
0.20%. This low FFA content promotes the potential of successful
transesterification reaction.
Effect of reaction time on FFA content reduction and yield of treated LGCPO
Validation of optimum esterification conditions
After optimizing the esterification reaction conditions it was found that the
optimum conditions for the pre-treatment stage were: 0.75% (wt/wt) PTSA to
, 8:1 molar ratio, 60oC temperature, 30 minutes reaction time. Using these
optimum conditions the FFA was reduced from 9.5% to 1%.
Conversion of Homogenoues Acids to DES
PTSA converison to DES using phosphonium Salt
Esterification of LGCPO using P-DES
Esterification reaction was carried out in order to achieve the acceptable industrial
limit of FFA content. The acid catalyst dosages, molar ratio, reaction temperature,
reaction time and mixing intensity are the main parameters affecting the
esterification reaction. Figure 4.22 shows the esterification reaction for the pre
0.20%. This low FFA content promotes the potential of successful
Effect of reaction time on FFA content reduction and yield of treated LGCPO
After optimizing the esterification reaction conditions it was found that the
stage were: 0.75% (wt/wt) PTSA to
C temperature, 30 minutes reaction time. Using these
optimum conditions the FFA was reduced from 9.5% to 1%.
Salt
Esterification reaction was carried out in order to achieve the acceptable industrial
limit of FFA content. The acid catalyst dosages, molar ratio, reaction temperature,
e main parameters affecting the
shows the esterification reaction for the pre-
87
treatment of LGCPO using P-DES catalyst. In order to confirm the successful
synthesis of P-DES, the melting point (M.P) was measured and it was in the range
of 43-47 °C which is much lower than the corresponding values of the individual
constituting compound (phoshoium salt and PTSA). This reduction in M.P after
mixing confirmed the formation of P-DES. The formation of the P-DES (Figure
4.21) was due to the hydrogen bonding between phoshonium salt and the hydrogen
bond donor (PTSA). These bonds tend to dislocalize the charge distribution around
the salt molecule causing a reduction in melting point.
Fig.4.21 Synthesis of P-DES
88
Fig.4.22 Esterification reaction using P-DES
4.3.1.2 Effect of P-DES catalyst
The P-DES catalyst dosage was optimized in the ranges of 1–3.5 wt%. The FFA
content limit was fixed to the recommended FFA content, i.e. 2% (Hayyan et al.,
2010a; 2011a). Figure 4.23 shows the effect of P-DES in LGCPO towards the yield
of treated oil, FFA content and their conversion to FAME. As mentioned above, the
FFA content in LGCPO was 9.3. This amount was reduced after a low loading of
catalyst to LGCPO (such as 0.25% and 0.5%), however, the FFA content was still
high and above the target limit. Using a catalyst dosage of 0.25%, 0.5% and 0.75%,
the achieved residual FFA content was 4.12%, 3.072 and 2.677%, respectively. On
the other hand, when the catalyst dosage was increased to 1% of P-DES to
LGCPO, the FFA content was reduced significantly to less than 2%. This High
catalytic strength is sufficient to treat the LGCPO during the course of the
esterification reaction. It was also found that small concentrations of TAG (less
than 10%) in LGCPO, can be converted to FAME using 1% of P-DES. There was
no enhancement in the treated LGCPO yield after pre-treatment and it was within
the range of 93-97%. Based on the yield of treated LGCPO, 1 wt/wt% (P-DES to
FFA + Methanol FAME + Water
89
LGCPO) resulted in 1.91% FFA content and the treated LGCPO yield was 96.6%
and a FAME conversion was 79.4%. Its worth mentioning that Hayyan et al.
(2010a) used 0.75% of PTSA to reduce the high FFA content (22.33%) in SPO to
less than 2% while Di Serio et al. (2008) used 6.4X10-5
mol of PTSA to treat the
FFA content in soybean oil from 20.5% to 1.1%.
Fig.4.23 Effect of P-DES dosage on the FFA reduction and yield of treated
LGCPO
4.3.1.3 Molar ratio effect
Sufficient molar ratio should be provided in order to effectively complete the
esterification reaction. The esterification reaction stoichiometry (Figure 2) shows
an ideal molar ratio of 1:1. Practically, this ratio is not enough to reduce the high
FFA content in acidic oils such as LGCPO. Therefore, the methanol loading was
varied at different ratios (1:1 to 20:1) as shown in Figure 4.24. Low loading of
0
20
40
60
80
100
120
0
2
4
6
8
10
0 0.5 1 1.5 2 2.5 3 3.5 4
Yie
ld%
& C
on
vers
ion
%
FF
A%
Dosage of P-DES wt%
FFA%
Limits of FFA%
Yield% of LGCPO
Conv. of FFA to FAME
90
methanol such as 1:1 or 1:5 resulted in a low reduction in FFA content. Based on
these results, reacting the FFA with insufficient amount of methanol, the reaction
tends to be slower, thus decreasing the FAME conversion significantly. A molar
ratio of 10:1 can reduce the FFA content significantly to less than 2%. Molar ratio
more than 10:1 did not enhance the FFA reduction. Therefore, in order to minimize
the consumption of methanol and to save the energy required to evaporate the
excess methanol, 10:1 molar ratio is selected as the optimum ratio for the pre-
treatment LGCPO using P-DES. At this molar ratio the FFA content was reduced
from 9.3% to 1.10% and the FAME conversion was 88.1%. While the yield of
treated LGCPO was in the range of 94-98% and there is no significant reduction
achieved at higher molar ratios. Hayyan et al (2010a) used PTSA to treat the high
FFA content in SPO and their study reported a similar optimum molar ratio. Man et
al.(2013), used 15:1 to treat the FFA content (3.49%) in CPO.
0
20
40
60
80
100
120
0
2
4
6
8
10
0 2 4 6 8 10 12 14 16 18 20 22
Yie
ld%
& C
on
vers
ion
%
FF
A%
Molar Ratio
FFA% Limits of FFA%
Yield% of treated LGCPO Conv.% of FFA to FAME
91
Fig.4.24 Effect of molar ratio on the FFA reduction, conversion of FFA to FAME
and the yield of treated LGCPO
4.3.1.4 Reaction temperature effect
Reaction temperature has an important role in the enhancement of chemical
reactions such as esterification. The esterification temperature was varied from a
low temperature of 40 °C to a high temperature of 80 °C, Figure 4.25. This is to
understand the temperature effect on the progress of the reation. In addition, the
results may be used for a further reaction kinetics investigation. As shown in
Figure 6, a reaction temperature of 80 °C shows a negative effect and the FFA
content was 2.07. On the other hand, a reaction temperature of 70 °C resulted in an
FFA content of 1.44% which is with the industrial acceptable limit. A lower
reaction temprature of 40 °C shows low conversion and FFA content reduction. An
FFA conversion to FAME of 3.75% and 2.57% were obtained for the temperatures
40 °C and 50 °C respectively. To optimize the energy requirements of the reaction,
a reaction temperature of 60 °C was selected. At this temperature, a high yield of
treated LGCPO and conversion of FFA to FAME was obtained, with a 1.52% FFA
reduction. Other of studies reported a similar reaction temperature as the optimum
for the esterification of acidic oils (Hayyan et al., 2010a; 2011a; 2011b; 2012a).
92
Fig.4.25. Effect of reaction temperature on the FFA reduction, conversion of FFA
to FAME and the yield of treated LGCPO
4.3.1.5 Effect of reaction time
The reaction time is a very important operating parameter due to its direct effect on
the cost and quality of biodiesel. Sufficient but not excessive reaction time must be
provided to achieve a complete and perfect reaction. The esterification reaction
time was optimized in the range of 3-120 min (Figure 4.26). There is no significant
effect on the yield of treated LGCPO at differ reaction time. It was found that the
majority of FFA content in LGCPO was removed within the first 30 minutes. 30
min reaction time can serve as the optimum reaction time for the esterification of
LGCPO. Half an hour of reaction time is sufficient to decrease the FFA content
from 9.3% to less than 1%. The yield of treated LGCPO was 96% with a 88.95%
FAME conversion. This indicates that the consumption rate of FFA in LGCPO was
found to be short. The results shown in Figure 4.26 indicated that additional
0
20
40
60
80
100
120
0
2
4
6
8
10
0 10 20 30 40 50 60 70 80 90
Yie
ld%
& c
on
ve
rsio
n%
FFA
%
Temperature oC
FFA% Limits of FFA%
Yield% of treated ACPO Conv.% of FFA to FAME
93
reaction time more than 30 minutes did not contributed in improving the reaction.
The fact that short reaction time is needed to complete the reaction indicates the
high catalytic activity of P-DES due the presence of the sulfonic group SO3H from
hydrogen bond donor (PTSA). The current results are much better than those
reported by a recent application of the IL 1-butyl-3-methyl-
imidazolium hydrogensulfate [bmim][HSO4] and triethylammoium
hydrogensulfate in the pre-treatment of FFA in CPO (Elsheikh et al., 2011; Man et
al., 2013). The reaction time required to reduce the FFA content to the minimum
limit was 120 min using [bmim][HSO4] and 180 min using (Et3NHSO4) (Elsheikh
et al., 2011; Man et al., 2013). The short reaction time for the esterification of
LGCPO will decrease the cost of the pre-treatment process significantly.
Fig.4.26. Effect of reaction time on the FFA reduction, conversion of FFA to
FAME and the yield of treated LGCPO
0
20
40
60
80
100
120
0
2
4
6
8
10
0 30 60 90 120 150
Yie
ld%
& C
on
vers
ion
%
FF
A%
Reaction Time min
FFA%
Limits of FFA%
Yield% of treated LGCPO
94
4.3.1.6 Validation of optimum conditions and catalyst recyclability study
The optimum esterification operating conditions using P-DES were 1% (wt/wt) P-
DES to LGCPO, 10:1 molar ratio, 60oC temperature, and 30 minutes reaction time.
At these reaction conditions, 0.88% FFA content was achieved, with 96% yield of
treated LGCPO and 84.2% FAME conversion. The yield of the final product after
transesterification and purification was 88.67% with 0.06% FFA and 97% ester
content. Figure 4.27 shows the FAME high conversion using P-DES in the
esterification of LGCPO within the first three recycle runs. It can be seen from
Figure 7 that the forth recycle run was slightly lower in terms of FAME
conversions due to lose of catalyst as a consequence of reuse. The catalyst loading
decreased due to some losses when the reactant was transferred between units as
well as the traces of catalyst remaining in the treated LGCPO. This change in
catalyst loading has considerable influence on the equilibrium FAME conversion
which explains the variation in reaction time among the different reaction cycles.
Therefore, in order to achieve the target (2% FFA content) without using new
dosage of catalyst, high loading of methanol as well as an increase in the reaction
time are recommended. The main advantage of using P-DES is due to its
recyclability, Using PTSA alone as a catalyst will no facilitate its recycling due to
its lose in the product.
95
Fig 4.27. FFA to FAME conversion at different catalyst recycling runs
4.3.1.8 Suggested Process Plant Layout
Figure 4.28 shows the layout of the proposed LGCPO pre-treatment process. In
order to prepare the P-DES, a Teflon coated mixer is recommended in the mixing
the PTSA and P-salt.
The process consists mainly of an esterification and transesterification reactors, an
evaporator to remove the excess methanol and the free water produced as by-
product from first and second reactions, a centrifuge to recover the catalyst and
separate the two phases (biodiesel and crude glycerol) and finally, a washing vessel
to purify the crude biodiesel produced after transesterification reaction. The
esterification reactor output is transferred to the evaporator followed by the
centrifuge to recover the catalyst. The treated LGCPO is then fed to the
transesterification reactor and potassium methoxide is added to carry out the
0
20
40
60
80
100
1 2 3 4
Recycle Runs
Co
nv
ers
ion
of
FF
A t
o F
AM
E
96
reaction. Untreated biodiesel and the crude glycerol are fed to the evaporator and
centrifuge in order to purify the products from excess methanol and to facilitate
fast separation. The crude biodiesel is finally fed to the washing vessel to purify
the product from contaminants, soap and traces of crude glycerol. The studied P-
DES will be then recycled for four times with the same experimental conditions as
indicated previously. The temperature is set at 60oC, and the molar ratio to 10:1.
97
Fig.4.28. Proposed schematic for the pre-treatment and biodiesel production form
of LGCPO. 1. Esterification reactor, 2. Evaporator, 3. Centrifuge,
4.Transesterification reactor, 5. Evaporator, 6. Centrifuge, 7.washing vessel.
Methanol
Tank
P-DES
KOH
LGCPO
Tank
1
4
Excess Methanol
2 Treated LGCPO
5 3
6
7
PURE CRUDE
GLYCEROL
PTSA
Allyl triphenyl
phosphonium
bromide
Recycled P-DES
98
4.4PTSA converison to DES using Ammonium Salt
4.3.1.1 Esterification of LGCPO using P-DES
3.2. Effect of ChCl-DES dosage
Using a fixed reaction time (60 min) and fixed molar ratio (10:1), the dosage of
ChCl-DES was varied in the range of 0.25-3.5wt%. Figure 4.29 shows the
preparation of ChCl-DES. While Figure 4.30 shows the influence of ChCl-DES on
the FAME conversion and the treated ACPO yield. Low dosage of ChCl-DES such
as 0.25 and 0.5% showed low conversion of FAME. A dosage above 0.5% attained
high catalytic activity. Catalyst dosage ratios of more than 0.5wt% attained a high
FAME conversion. There was no significant change in the yield of treated ACPO
under all tested catalyst dosage ratios. Based on the highest conversion of FFA to
FAME, 0.75wt/wt % was selected as optimum dosage of solvent for esterification
of ACPO. The FFA content reduced from 9% to 0.43% using 0.75 wt/wt % while
the FAME conversion and treated SPO yield were 95% and 96%. The FAME
conversion was almost equivalent at high dosages (1-3.5wt/wt %) of solvent
loading because the reaction has reached equilibrium and the majority of FFA
content has already converted to FAME.
The results showed that the yield of treated ACPO is proportionally related to the
solvent dosage. The catalyst consumption (C.C.) of ChCl-DES at 0.75% was 7.8
mg of solvent to produce 1 gram of treated ACPO. After 0.75% the yield was not
changed significantly with an increase in C.C. This increase in C.C. will result in
increasing the cost of ACPO pre-treatment and consequently, the biodiesel
production cost. Hayyan et al (2010a; 2011b) used PTSA and ESA as acidic
esterification catalysts and they reported that the optimum catalyst to oil dosage
needed to reduce the FFA content to the acceptable limit prior to the
transesterification reaction is 0.75%.
ChCl Salt
99
needed to reduce the FFA content to the acceptable limit prior to the
transesterification reaction is 0.75%.
ChCl-DES
Figure 4.29 Preparation of ChCl based DES
ChCl-DES
needed to reduce the FFA content to the acceptable limit prior to the
Preparation of ChCl based DES
PTSA
Figure 4.30 Effect of ChCl
3.3. Effect of molar ratio
The alcohol is one of the ingredients that affects to the overall production cost of
biodiesel. In this study the molar ratio of methanol to
range of 3:1 to 20:1. Figure
FFA to FAME and the corresponding yield of treated ACPO. No significant FAME
conversion change was observed for molar ratios larger than 10:1. The yield of
treated oil was almost constant for the differen
minimum of 10:1 molar ratio was required to covert the FFA content of
FAME with high conversion (96.6%) suitable for transesterification reaction.
100
Effect of ChCl-DES dosage ratio on the conversion of FFA to FAME
and the corresponding yield of treated ACPO
.3. Effect of molar ratio
The alcohol is one of the ingredients that affects to the overall production cost of
In this study the molar ratio of methanol to
range of 3:1 to 20:1. Figure 4.31 depicts the effect of molar ratio on conversion of
FFA to FAME and the corresponding yield of treated ACPO. No significant FAME
conversion change was observed for molar ratios larger than 10:1. The yield of
treated oil was almost constant for the different ratios of methanol to
minimum of 10:1 molar ratio was required to covert the FFA content of
FAME with high conversion (96.6%) suitable for transesterification reaction.
DES dosage ratio on the conversion of FFA to FAME
ACPO
The alcohol is one of the ingredients that affects to the overall production cost of
In this study the molar ratio of methanol to ACPO was varied in the
depicts the effect of molar ratio on conversion of
FFA to FAME and the corresponding yield of treated ACPO. No significant FAME
conversion change was observed for molar ratios larger than 10:1. The yield of
t ratios of methanol to ACPO. A
minimum of 10:1 molar ratio was required to covert the FFA content of ACPO to
FAME with high conversion (96.6%) suitable for transesterification reaction.
101
Figure 4.31: Effect of molar ratio on conversion of FFA to FAME and the
corresponding yield of treated ACPO
3.4. Effect of reaction temperature
Figure 4.32 shows the influence of temperature on the esterification reaction. The
results indicated that the increase in reaction temperature enhanced the reaction to
completion within 30-60 minutes. Figure 4.32 indicates that a reaction temperature
of 60oC was kinetically enough to reach a stable high conversion and further
increase in the reaction temperature did not show any significant effect in the
conversion of FFA to FAME and yield of treated ACPO. Both yield of treated oil
and conversion were high at 60oC compared to the lower reaction temperature of
40oC and 50
oC. Hence, an optimum reaction temperature of 60
oC was selected for
esterification of FFA content in ACPO in order to minimize use of energy and to
make the pre-treatment process economically feasible.
0
10
20
30
40
50
60
70
80
90
100
110
0 2 4 6 8 10 12 14 16 18 20 22
Yie
ld &
Co
nvers
ion
%
Molar Ratio
Yield% of treated ACPO Conv.% of FFA to FAME
102
Figure 4.32 Effect of reaction temperature on conversion of FFA to FAME and
the corresponding yield of treated ACPO
3.5. Effect of reaction time
Reaction time plays a crucial role in the progress and extent of chemical reactions.
It is used as an important parameter in kinetics studies and design of reactors.
Figure 4.33, illustrates the effect of reaction time on the conversion of ACPO FFA
content to FAME as well as the yield of treated ACPO. In order to thoroughly
investigate the effect of esterification reaction time on the extent of ACPO pre-
treatment, the current study considered a wide range of reaction time (3-150 min).
The FAME conversion increased as the reaction time evolved. At the first 10
minutes of reaction, the FFA content was reduced to form FAME in high
concentration as shown in Figure 4.33. Sufficient loading of active ChCl-DES
0
10
20
30
40
50
60
70
80
90
100
110
0 10 20 30 40 50 60 70 80 90
Yie
ld &
Co
nve
rsio
n%
Temperature oC
Yield% of treated ACPO Conv.% of FFA to FAME
103
catalyst with enough reaction time increases the conversion significantly. After 30
minutes of reaction, the FAME conversion to reached equilibrium. Therefore, it is
concluded that a reaction time of 30 minters was sufficient to complete the
esterification reaction. Many studies found 60 min as an optimum reaction time
for esterification of acidic oils such as waste cooking oil, SPO and ACPO.
Figure 4.33: Effect of reaction time on the conversion of FFA to FAME and
the corresponding yield of treated ACPO
3.6. Validation of Optimal Pre-treatment Conditions
From the previous sections, the optimum conditions using the ChCl-DES catalyst
were: 0.75% (wt/wt) dosage of acid to ACPO, 10:1 molar ratio, 60oC reaction
temperature at 30 minutes reaction time. The use of this catalyst was verified by
conducting the esterification reaction at these optimum operating. Using these
0102030405060708090
100110
0 30 60 90 120 150
Yie
ld &
Co
nvers
ion
%
Reaction Time min
Yield% of treated ACPO conv.% of FFA to FAME
104
optimum conditions, the amount of FFA was reduced from 9% to less than 1%.
FFA conversion to FAME was 96% while the yield of treated ACPO was 97%.
3.7. Catalyst recycling study
Recyclability experiments of the catalyst under consideration revealed that the first
(fresh ChCl-DES) and second recycling runs attained high conversion of FFA to
FAME as shown in Table 1. The third catalyst reuse run showed a slight reduction
in the conversion hence more reaction time is recommended to reach the same
reaction yield of the previous two runs. These three recycle experiments were
performed without adding any new amount of ChCl-DES which gives an
indication that this catalyst has high activity in the esterification reaction compared
to conventional acidic catalysts. The successful recycling of ChCl-DES depends on
the catalyst separation efficiency via centrifugation. These results reflect that
ChCl-DES can be reused in the esterification reaction of ACPO before considering
catalyst regeneration.
Table 1: Effect of recycling runs of ChCl-DES on the FFA conversion to
FAME
Run
#
Conversion
(%)
Yield
(%)
1 97 96
2 96 95
3 89 95
105
Proposed process flowsheet
The abovementioned ACPO processing strategy may be practically realized in a
process flowsheet as depicted in Figure 4.34. ACPO is pre-heated first due to its
high viscosity. The ChCl-DES is prepared by mixing 1 mole ChCl salt with 3
moles PTSA at a temperature between 60-70°C and a stirrer speed of 350 rpm for 3
hours. A high mixing temperature is not recommended due to the possibility of
PTSA decomposition. Therefore, a special isolated mixing reactor should be used.
The reactor should be coated with Teflon to avoid corrosion issues during the
course of mixing. Special care must be taken during the mixing and PTSA should
be added to the salt in small consecutive quantities.
The ChCl-DES is mixed with methanol and fed to the esterification reactor. The
pre-heated mixture of ChCl-DES and methanol is reacted under the optimum
conditions to produce treated ACPO. After the esterification reaction, the treated
ACPO and the mixture of two solvents (Methanol and ChCl-DES) are transferred
to the evaporation system to recover excess methanol and to mix again with ChCl-
DES. In the centrifugation stage, the mixture of treated ACPO and ChCl-DES is
separated due to differences in the density and viscosity of the two materials.
Thirty minutes of mixing time is sufficient to separate the treated ACPO from
ChCl-DES. The separated solvent is mixed again with methanol in the mixing
vessel. Treated ACPO which is the raw material for biodiesel production is sent to
the alkaline transesterification reactor. KOH is preferred over NaOH as an alkaline
catalyst due to its lower soap formation. The esterification reaction is followed by
evaporation to purify the crude biodiesel and to recycle the excess methanol. In
106
order to separate the two products (crude glycerol and biodiesel), a settling vessel
is used. After settling, crude biodiesel is washed with water to remove impurities
of soap and the traces of catalyst.
Figure 4.34 Proposed process flowchart to produce biodiesel from ACPO using
ChCl-DES
5
Mixing
Methanol
ChCl-DES
ACP
Methanol and
ChCl-DES
Evaporation Pre-heating Esterification
Centrifugatio
Methanol
and KOH
Treated
ACPO Washing TransesterificatioEvaporation Settling
Mixing
ChCl PTSA
Biodiesel Crude Glycerol
107
6 CHAPTER V
CONCLUSIONS AND RECOMMENDATIONS
5.1 Study of ACPO Characteristics
Study of characteristics of the material can estimate the right way of selection of
process, subsequently decreasing the cost of process and increasing the selectivity
of desired products. It was found that the characteristics of ACPO used in this
study are within the ranges of other feedstocks (ACPO) from different mills in
Malaysia. Average molecular weight was calculated based on saponification value,
and it was 816 g/mole. Study of fatty acid compositions of ACPO are very
important to identify the carbon chains and its properties. The results showed that
the highest fatty acids in SPO were oleic, palmitic, linoleic and stearic acid.
Saturated fatty acids in SPO were 47.17 wt% while unsaturated fatty acids were
52.83 wt%. Due its high percentage of saturated fatty acids and FFA, SPO exists in
semisolid phase or solid phase at room temperature (30±2oC). As a result, SPO has
higher pour and cloud point as compared to normal CPO. Study of characteristics
of SPO shows that SPO was low quality and non edible oil, which was the main
reason for low price of SPO. Consequently the low price of feedstock for biodiesel
production gives an advantage to the process technology and the total cost of
production will be lower.
5. 2 Screening of Homogenous Acids
Laboratory scale batch-wise experiments were conducted to produce high quality
biodiesel from ACPO as agro-industrial feedstock. ACPO is significant raw material
for biodiesel production with a pre-treatment process by an esterification reaction
108
using ESA as a catalyst. The optimum conditions for esterification reaction using
homogenous catalyst such as ESA, MSA, CSA and BZSA and PTSA were 0.75%
wt/wt acid to ACPO with 10:1 molar ratio, 60oC reaction temperature at 30
minutes. After validating, the FFA content was reduced from 8-10 % to less than
1% with high yield of treated ACPO and conversion of FFA to FAME. Results of
this study showed that these types of homogenous acids have high catalytic
activity. The biodiesel produced met the standards specifications for biodiesel fuel
(EN 14214 and ASTM D6751). PTSA was used for further studies due to low cost
of this acid and the high catalytic activity.
5.3 Development of Homogenous Acids via Conversion these Acids to DES
This study was conducted in order to evaluate the feasibility of producing
biodiesel from ACPO using a DES as a catalyst. The study revealed that ACPO is a
suitable feedstock for biodiesel production using a pre-treatment stage with
ammonium or phosphonium based DES. The treated ACPO is a promising
industrial raw material for biodiesel production using a second stage
transesterification reaction. The produced biodiesel was characterized and
compared to other standard biodiesels. The optimum esterification reaction
conditions were 0.75% wt/wt (catalyst to ACPO) for ammonium based DES while
the optimum dosage of catalyst for phosphnuim was 1%. The molar ratio of both
DES is 10:1 molar ratio at 30 minutes reaction time and 60oC. Using these
conditions the conversion of FAME was 96% and the yield of treated ACPO was
97%. The catalytic activity of ammonium based DES is higher than phosphnuim
based DES. The yield of biodiesel was 92% with 0.07% FFA content (0.14% acid
value) while ester content was 96%. The biodiesel produced from ACPO met the
109
international standard specification EN 14214.
The main novelties of this work are listed below:
1- This is the first work in the world for DES application in biodiesel
production using two stage processes.
2- This study proposed new class of deep eutectic solvent as alternative to ILs
and can be designed according to the application.
3- When PTSA converted to DES the unfavorable physical properties such
hygroscopic will be eliminated because DES is moisture stable as well as the
corrosion and toxicity levels will be decreased.
4- The current study converted PTSA to DES and we reported for first time
recycling of the catalyst. This technique can be applied for wide a range of acids.
5- DES can be design according to the application and then can be applied for
different types of reactions.
6- Because DES can be synthesized in such a way that it is solid form at room
temperature, then the storage and transport will be much easier than powder or
liquid forms.
7- DES can be directly applied for industrial applications due to their above-
mentioned merits.
8- There are limited studies in the application of industrial low grade crude
palm oil, and in our paper we highlighted the importance of using this Bio-
industrial resource for biodiesel production.
110
Bibliography
Abbott AP, Capper G, Davies DL, Rasheed RK, Tambyrajah V. Novel solvent
properties of choline chloride/urea mixtures. Chem Com 2003: 70-71.
Abbott AP, Capper G, McKenzie KJ, Ryder KS. Electrodeposition of zinc–tin
alloys from deep eutectic solvents based on choline chloride. J Electroanal Chem
2007; 599: 288-294.
Abbott AP, Griffith J, Nandhra S, O'Connor C, Postlethwaite S, Ryder KS, et al.
Sustained electroless deposition of metallic silver from a choline chloride-based
ionic liquid. Surf Coat Technol, 2008; 202: 2033-2039.
Abbott, A.P., Capper, G., Davies, D.L., Rasheed, R.K., Tambyrajah, V., 2003.
Novel solvent properties of choline chloride/urea mixtures. Chem. Com. 70-71.
Abbott, A.P., Griffith, J., Nandhra, S., O’Connor, C., Postlethwaite, S., Ryder,
K.S., Smith, E.L. 2008. Sustained electroless deposition of metallic silver from a
choline chloride-based ionic liquid. Surf. Coat. Technol. 202, 2033–2039.
Abraham MA. Sustainability seince and engineering defining principles. Toledo,
OH, USA. Elsevier; 2006.
Alamu, O.J., Akintola, T.A., Enweremadu, C.C., Adeleke, A.E. 2008.
Characterization of palm-kernel oil biodiesel produced through NaOH-catalysed
transesterification Process. Sci Res Essays 3, 308-311.
American Oil Chemists’ Society (AOCS), 1997. Ca 5a-40: free fatty acids. In:
Official
Antolin, G., Tinaut, F.V., Briceno, Y., Castrano, V., Perez C, Ramirez. A.I., 2002.
Optimization of biodiesel production by sunflower oil transesterification.
Bioresour. Technol. 83, 111-114.
Aranda, D.A.G., Santos, R.T.P., Tapanes, N.C.O., Ramos, A.L.D., Antunes,
O.A.C., 2008. Acid-catalyzed homogenous esterification reaction for palm fatty
acids. Catal Lett. 122: 20-25.
Ashok Pandey, 2009, Hand book of plant-based biofuels. CRC Press, Taylor &
Francis Group, LLC. New York.
Atadashi IM, Aroua MK, Abdul Aziz AR, Sulaiman NMN. The effects of water on
biodiesel production and refining technologies: A review. Renew Sustain Energy
Rev 2012; 16: 3456-3470.
Atadashi IM, Aroua MK, Aziz AA. High quality biodiesel and its diesel engine
application: A review. Renew Sustain Energy Rev, 2010; 14: 1999-2008.
111
Berrios M, Skelton RL. Comparison of purification methods for biodiesel. Chem
Eng J 2008; 144: 459–465.
Bhatti, H. N., Hanif, M. A., Qasim, M., Rehman, A. U., 2008. Biodiesel from
waste tallow. Fuel. 87, 2961-2966.
Canackci M, Gerpen JV. Biodiesel production from oils and fats with high free
fatty acids. Trans ASAE 2001; 44(6) : 1429–1436.
Canakci, M. (2007). The potential of restaurant waste lipids as biodiesel
feedstocks. Bioresource Technology, 98, 183–190.
Canakci, M., van Gerpen, J., 2001. Biodiesel production from oils and fats with
high fatty acid feedstocks. Trans. ASAE 46 (4), 945–954.
Canakci, M., van Gerpen, J., 2003. A pilot plant to produce biodiesel from high
free
Chattopadhyay S, Karemore A, Das S, Deysarkar A, Sen R. Biocatalytic
production of biodiesel from cottonseed oil: Standardization of process parameters
and comparison of fuel characteristics. Appl Energ 2011; 88: 1251-1256.
Chew, T.L. and Bhatia, S. (2008). Cataytic processes towards the production of
biofuels in a palm oil and oil palm biomass-based biorefinery. Bioresource
Technology, 99, 7911-7922.
Chongkhong, S., Tongurai, C., Chetpattananondh, P., Bunyakan, C., 2007.
Biodiesel production by esterification of palm oil fatty acid distillate. Biomass
Bioenerg. 31, 563-568.
Cooper, E.R., Andrews, C.D., Wheatly, P.S., Webb, P.B., Wormald, P., Morris,
R.E. 2004. Ionic liquids and eutectic mixtures as solvent and template in synthesis
of zeolite analogous. Nature 340, 1012–1016.
Crabbe, E., Nolasco-Hipolito, C., Kobayashi, G., Sonomoto, K., Ishizaki, A., 2001.
Biodiesel production from crude palm oil and evaluation of butanol extraction and
fuel properties. Process Biochem. 37, 65-71.
Cvengros J, Cvengrosova Z. Used frying oils and fats and their utilization in the
production of methyl esters of high fatty acids. Biomass Bioenergy 2004; 27:173–
181.
D.Y.C. Leung, X. Wu, M.K.H. Leung. “A review on biodiesel production using
catalyzed transesterification”. J Applied Energy, 2009;
doi:10.1016/j.apenergy.2009.10.006.
112
De Santi, V., Cardellini, F., Brinchi, L., Germani, R., 2012. Novel brønsted acidic
deep eutectic solvent as reaction media for esterification of carboxylic acid with
alcohols. Tetrahedron Lett. 53, 5151-5155.
Demirbas, A., 2009. Green Energy and Technology. Springer, London.
Di Serio M, Tesser R, Pengmei L, Santacesaria E. Heterogenous catalyst for
biodiesel production. Energy Fuels 2008; 22: 207–217.
Dias JM, Alvim-Ferraz MCM, Almeida MF. Comparison of different
homogeneous alkali catalysts during transesterification of waste and virgin oils and
evaluation of biodiesel quality. Fuel 2008; 87:3572–3580.
Echim, C., Verhe, R., De Greyt, W., Stevens, C., 2009. Production of biodiesel
from side-stream refining products. Energ. Environ. Sci. 2, 1131–1141.
Elsheikh, Y.A., Man, Z., Bustam, M.A., Yusup, S., Wilfred, C.D., 2011. Brønsted
imidazolium ionic liquids: Synthesis and comparison of their catalytic activities as
pre-catalyst for biodiesel production through two stage process. Energ. Convers.
Manage. 52, 804–809.
Encinar JM, Gonzlez JF, Rodrguez-Reinares A. Ethanolysis of used frying oil.
Biodiesel preparation and characterization. Fuel Proc Technol 2007; 88 (5):513–
522.
Enweremadu CC, Mbarawa MM. Technical aspects of production and analysis of
biodiesel from used cooking oil – A review. Renew Sustain Energy Rev (2009),
doi:10.1016/j.reser.2009.06.007.
Felizardo P, Correia MJN, Raposo I, Mendes JF, Berkemeier R, Bordado J.
Production of biodiesel from waste frying oil. Waste Manage 2006;26: 487–494.
Felizardo P, Correia MJN, Raposo I, Mendes JF, Berkemeier R, Bordado J.
Production of biodiesel from waste frying oil. Waste Manage 2006;26: 487–494.
free fatty acids. Trans. ASAE 44 (6), 1429–1436.
Freedman B, Pryde EH, Mounts TL. Variables affecting the yields of fatty esters
from transesterified vegetable oils. JAOCS 1984; 61 (10):1638-1643.
Freedman, B., Pryde, E.H., Mounts, T.L., 1984. Variables affecting the yields of
fatty 580 esters from transesterified vegetable oils. JAOCS 61 (10), 1638–1643.
Gerpen JV, Shanks B, Pruszko R, Clements D, Knothe G. Biodiesel production
technology: Subcontractor Report,NREL/SR, Colorado, 2004; pp 50-54.
113
Ghadge SV, Raheman H. Biodiesel production from mahua (Madhuca indica) oil
having high free fatty acids. Biomass Bioenerg 2005; 28: 601–605.
Goh, S. H., Choo, Y.M., Ong, A.S.H., 1985. Minor components of palm oil. J. Am.
Oil Chem. Soc. 62, 237-240.
Guan, G., Kusakabe, K., Yamasaki, S., 2009. Tri-potassium phosphate as a solid
catalyst for biodiesel production from waste cooking oil. Fuel Process. Technol.
90, 520-524.
Gunstone, F.D., 2002. Vegetable oils in food technology composition, properties
and uses. Blackwell publishing Ltd. Oxford.
Guo F, Xiu ZL, Liang ZX. Synthesis of biodiesel from acidified soybean soapstock
using a lignin-derived carbonaceous catalyst. Appl Energ 2012; 98: 47-52.
Haas M, Michalski P, Runyon S, Nunez A, Scott K. Production of FAME from
acid oil, a by-product of vegetable oil refining. Journal of the American Oil
Chemists' Society, 2003; 80: 97-102.
Hashim MA, Hayyan A, Mjalli FS, Hayyan M, AlNashef IM. Pre-treatment of
crude palm oil using super acid for biodiesel productionInt. J of Sus Water & Envi
Syst 2011; 3: 19-24.
Hayyan A, Alam Md Z, Kabbashi NA, Mirghani MES, Hakimi NI NM, Siran YM.
Pretreatment of sludge palm oil for biodiesel production by esterification. In:
Symposium of Malaysian Chemical Engineers; 2008. 2.p. 485-490.
Hayyan A, Alam Md Z, Kabbashi NA, Mirghani MES, Hakimi NINM, Siran YM,
Tahiruddin S, Al-Saadi MA. Biodiesel production from sludge palm oil by
ultrasonic energy In: Malaysian International Conference on Trends in Bioprocess
Engineering (MICOTriBE); 2009b. p. 510-516.
Hayyan M, Mjalli FS, Hashim, MA, AlNashef IM, Al-Zahrani SM, Chooi KL.
Generation of superoxide ion in 1-butyl-1-methylpyrrolidinium trifluoroacetate and
its application in the destruction of chloroethanes. J Mol Liq 2012;167: 28-33.
Hayyan, A., Alam, M.Z., Mirghani, M.E.S., Kabbashi, N.A., Hakimi, N.I.N.M.,
Siran, Y.M., Tahiruddin, S., 2011a. Reduction of high content of free fatty acid in
sludge palm oil via acid catalyst for biodiesel production. Fuel Process. Technol.
92, 920-924.
Hayyan, A., Alam, Md. Z., Mirghani, M.E.S., Kabbashi, N.A., Hakimi, N.I.N.M.,
Siran, Y.M., Tahiruddin, S., 2011a. Hayyan, A Reduction of high content of free
fatty acid in sludge palm oil via acid catalyst for biodiesel production. Fuel
Process. Technol. 92, 920–924.
114
Hayyan, A., Mjalli, F. S., Hashim, M. A., Hayyan, M., AlNashef, I. M., Al-
Zahrani, S. M., Al-Saadi, M. A. 2011b. Ethanesulfonic acid-based esterification of
industrial acidic crude palm oil for biodiesel production. Bioresour. Technol. 102,
9564−9570.
Hayyan, M., Mjalli, F. S., Hashim, M. A., AlNashef, I. M., 2010a. A novel
technique for separating glycerine from palm oil-based biodiesel using ionic
liquids, Fuel Process. Technol. 91, 116-120.
Helwani, Z., Othman, M.R., Aziz, N., Fernando, W.J.N., Kim, J. (2009).
Technologies for production of biodiesel focusing on green catalytic techniques: A
review. Fuel Processing Technology 90 ,1502–1514.
Hu, Y., Wang, Z., Huang, X., Chen, L., 2004. Physical and electrochemical
properties of new binary room-temperature molten salt electrolyte based on
LiBETI and acetamide. Solid State Ionics 175, 277–280.
Indira, T. N., J. Hemavathy, S. Khatoon, A. G. G. Krishna, and S. Bhattacharya.
2000. Water degumming of rice bran oil: A response surface approach. J. Food
Eng. 43: 83–90.
Issariyakul T, Kulkarni MG, Dalai AK, Bakhshi NN. Production of biodiesel from
waste fryer grease using mixed methanol/ethanol system. Fuel Process Technol
2007;88:429–436.
Issariyakul T, Kulkarni MG, Dalai AK, Bakhshi NN. Production of biodiesel from
waste fryer grease using mixed methanol/ethanol system. Fuel Process Technol
2007; 88: 429-436.
Kalam, M.A., and Masjuki, H.H., 2002. Biodiesel from palm oil-an analysis of its
proerties and potential. Biomass Bioenerg. 23, 471- 479.
Karaosmonoglu F. (1999). Vegetable oil fuels: a review. Energy Source; 21:221–
31.
Kareem MA, Mjalli FS, Hashim MA, AlNashef IM. Phosphonium-based ionic
liquids analogues and their physical properties. J Chem Eng Data 2010; 55: 4632-
4637.
Kheang LS, Foon CS, May CY, Nagan MA. A study of residue oils recovered
from spent bleaching earth. Am J Appl Sci 2006; 10: 2063-2067.
Kheang LS, May CY, Foon CS, Ngan MA. Recovery and conversion of palm
olein-derived used frying oil to methyl estyers for biodiesel. J palm oil research
2006; 18: 247-252.
115
Kheang LS, May CY, Foon CS, Ngan MA. Recovery and conversion of palm
olein-derived used frying oil to methyl estyers for biodiesel. J palm oil research
2006; 18: 247-252.
Ki-Teak L, Foglia TA. Production of alkyl ester as biodiesel from fractionated lard
and restaurant grease. J Am Oil Chem Soc 2002;79(2):191–5.
Knothe G, Dunn RO, Bagby MO. Biodiesel: the use of vegetable oils and their
derivatives as alternative diesel fuels. In: ACS symposium series no. 666: fuels and
chemicals from biomass; 1997.p. 172–208.
Krawczyk, T., 1996. Biodiesel – alternative fuel makes inroads but hurdles remain.
INFORM 7, 801–829.
Kuntom, A., Lin, S.W., Ai,T.Y., Idris, N.A., Yusof, M., Sue, T.T., Ibrahim, N.A.,
2005. Malaysian Palm Oil Board (MPOB) Test Methods. MPOB, Bangi. Malaysia.
Leung, D. Y. C., Guo, Y., 2006. Transesterification of neat and used frying oil:
Optimization for biodiesel production. Fuel process Technology. 87, 883-890.
Lin, S. W., 1989. Quality Index for crude palm oil. PORIM. 89, (00149) d.
Liu, K., 1994. Preparation of fatty acid methyl esters for gas-chromatographic
analysis of lipids in biological materials. J. Am. Oil Chem. Soc. 71 (11), 1179–
1187.
Long T, Deng Y, Gan S, Chen J. Application of choline chloride·xZnCl2 ionic
liquids for preparation of biodiesel. Chin J Chem Eng 2010; 18: 322-327.
Long, T., Deng, Y., Gan, S., Chen, J., 2010. Application of Choline
Chloride·xZnCl2 Ionic Liquids for Preparation of Biodiesel. Chin. J. Chem. Eng.
18, 322-327.
Lotero, E., Liu, Y., Lopez, D.E., Suwannakarn, K., Bruce, D.A., and Goodwin,
J.G. (2005). Synthesis of biodiesel via acid catalysis. Industrial and Engineering
Chemistry Research, 44, 5353-5363.
M. Naik, L.C. Meher, S.N. Naik, L.M. Das, Production of biodiesel from high free
fatty acid Karanja (pongamia pinnata) oil, Biomass Bioenerg 32 (2008) 354-357.
Ma, F., Hanna, M.A., 1999. Biodiesel production: a review. Bioresour. Technol.
70, 1–15
Malaysian palm oil board. 2010. Annual Statistics report, MPOB, Bangi. Malaysia.
116
Man, Z., Elsheikh, Y.A., Bustam, M.A., Yusup, S., Mutalib, M.I.A., Muhammad,
N., 2013. A Brønsted ammonium ionic liquid-KOH two-stage catalyst for biodiesel
synthesis from crude palm oil. Ind Crops Products. 41, 144-149.
Mazzocchia C, Modica G, Nannicini R, Kaddouri A. Fatty acid methyl esters
synthesis from triglycerides over heterogeneous catalysts in presence of
microwaves. CR Chimie 2002 ;7: 601.
Mazzocchia C, Modica G, Nannicini R, Kaddouri A. Fatty acid methyl esters
synthesis from triglycerides over heterogeneous catalysts in presence of
microwaves. CR Chimie ;7: 601.
Meher, L.C., Vidya Sagar, D., and Naik, S.N. (2006). Technical aspects of
biodiesel production by transesterification–A review. Renewable and Sustainable
Energy Reviews, 10:248–268.
Methods and Recommended Practices of the AOCS, fifth ed. American Oil
Chemists’ Society Press, Champaign, IL.
Mjalli, F.S., Hussain, M.A., 2009. Approximate predictive versus self-tuning
daptive control strategies of biodiesel reactors. Ind. Eng. Chem. Res. 48, 11034–
11047.
Mjalli, F.S., San, L.K. Yin, K.C., Hussain, M.A., 2009. Dynamics and control of a
biodiesel transesterification reactor. Chem. Eng. Technol. 32 (1), 13-26.
Montefrio MJ, Xinwen T, Obbard JP. Recovery and pre-treatment of fats, oil and
grease from grease interceptors for biodiesel production. Appl Energ 2010; 87:
3155-3161.
Naik, M., Meher, L.C., Naik, S.N., Das, L.M., 2008. Production of biodiesel from
high free fatty acid Karanja (Pongamia pinnata) oil. Biomass Bioenergy 32, 354–
357.
Naushad M, Alothman ZA, Khan AB, Ali M, Effect of ionic liquid on activity,
stability, and structure of enzymes: A review. Int J Biol Macromol 2012; 51: 555-
560.
Olivier-Bourbigou, H., Magna, L., Morvan, D. 2010. Ionic Liquids and Catalysis:
Recent progress from knowledge to applications. Applied Catalysis A: General,
373:1-56.
Paolo B, Lubricants and hydraulic fluids. In: Gunstone FD, Hamilton RJ, editors.
Oleochemical manufacture and application, England: Sheffield Academic Press;
2001, p. 83-84.
Park, J.Y., Kim, D.K., Lee, J.S., 2010. Esterification of free fatty acids using
117
water-tolerable Amberlyst as a heterogeneous catalyst. Bioresour. Technol. 101,
S62–S65.
Predojevic ZJ. The production of biodiesel from waste frying oils: a comparison of
different purification steps. Fuel 2008; 87:3522–3528.
Rajam, L., D. R. S. Kumar, A. Sundaresan, and C. Arumughan. 2005. A novel
process for physically refining rice bran oil through simultaneous degumming and
dewaxing. J. Am. Oil Chem. Soc. 82(3): 213–220.
Ramadhas, A.S., Jayaraj, S., Muraleedharan, C., 2005. Biodiesel production from
high FA rubber seed oil. Fuel 84, 335–340.
Sahoo, P.K., Das, L.M., Babu, M.K.G, and Naik, S.N. (2007). Biodiesel
development from high acid value polanga seed oil and performance evaluation in
a CI engine. Fuel, 86 448-454.
Saifuddin N, Chua KH. Production of ethyl ester (biodiesel) from used frying oil:
optimization of transesterification process using microwave irradiation. Malaysian
J Chem 2004; 6(1):77–82.
Saifuddin N, Chua KH. Production of ethyl ester (biodiesel) from used frying oil:
optimization of transesterification process using microwave irradiation. Malaysian
J Chem 2004; 6(1):77–82.
Santos FFP, Malveira JQ, Cruz MGA, Fernandes FAN production of biodiesel by
ultrasound assisted esterification of Oreochromis niloticus oil. Fuel 2010; 89: 275-
279.
Shahbaz K, Mjalli FS, Hashim MA, AlNashef IM. Eutectic solvents for the
removal of residual palm oil-based biodiesel catalyst. Sep Purif Technol 2011; 81:
216-222.
Shahidi, F., 2005. Bailey’s industrial oil & fat products. Vol 6. Published by John
Wily & Sons, Inc., Hoboken, New Jersey.
Sharma, Y.C., Singh, B., and Upadhyay S.N. (2008) Advancements in
development and characterization of biodiesel: A review, Fuel, 87 2355-2373.
Shu Q, Gao J, Nawaz Z, Liao Y, Wang D, Wang J. Synthesis of biodiesel from
waste vegetable oil with large amounts of free fatty acids using a carbon-based
solid acid catalyst. Appl Energ, 87; 2010: 2589-2596.
Shu Q, Zhang Q, Xu GH, Wang JF. Preparation of biodiesel using s-MWCNT
catalysts and the coupling of reaction and separation. Food Bioprod Process 2009;
8:164-70.
118
Singh, B.S., Lobo, H.R., Shankarling, G.S., 2012. Choline chloride based eutectic
solvents: Magical catalytic system for carbon–carbon bond formation in the rapid
synthesis of β-hydroxy functionalized derivatives. Catal. Commun. 24, 70-74.
Singh, S.P., and Singh, D. (2010). Biodiesel production through the use of
different sources and characterization of oils and their esters as the substitute of
diesel: A review. Renewable and Sustainable Energy Reviews, 14, 200–216.
Sousa LL, Lucena IL, Fernandes FAN. Transesterification of castor oil: Effect of
the acid value and neutralization of the oil. Fuel Process Technol 2010; 91: 194-
196.
Srivastava, A., and Prasad, R. (2000). Triglycerides-based diesel fuels. Renewable
and Sustainable Energy Reviews, 4, 111-133.
Stavarache C, Vinatoru M, Maeda Y. Ultrasonic versus silent methylation of
vegetable oils. Ultrason Sonochem 2006;13:401–407.
Stavarache C, Vinatoru M, Nishimura R, Maeda Y. Fatty acids methyl esters from
vegetable oil by means of ultrasonic energy. Ultrason Sonochem 2005;12:367372.
Suppalakpanya k, Ratanawilai SB, Tongurai C. Production of ethyl ester from
esterified crude palm oil by microwave with dry washing by bleaching earth. Appl
Energy 2010; doi:10.1016/j.apenergy.2009.12.006
Supple B, Holward-Hildige R, Gonzalez-Gomez E, Leahy JJ. The effect of steam
treating waste cooking oil on the yield of methyl ester. J Am Oil Chem Soc
2002;79(2):175–8.
Tan. C.H., Ghazali, H.M., Kuntom, A., Tan, C.P., Ariffin, A.A., 2009.Extraction
and physicochemical properties of low free fatty acid crude palm oil. Food
Chemistry, 113, 645-650.
Tesser R, Casale L, Verde D, Di Serio M, Santacesaria E. Kinetics and modeling
of fatty acids esterification on acid exchange resins. Chem Eng J 2010; 157:539-
550.
Veljkovic VB, Lakicevic SH, Stamenkovic OS, Todorovic ZB, Lazic ML.
Biodiesel production from tobacco (Nicotiana tabacum L.) seed oil with a high
content of free fatty acids. Fuel 2006; 85: 2671–5.
Vieira, A.P.de A., Da Silva, M.A.P., Langone, M.A.P., 2006. Biodiesel production
via esterification reactions catalyzed by lipase. Lat. Am. Appl. Res. 36,283-288.
Wang SM, Chen WL, Wang EB, Li YG, Feng XJ, Liu L. Three new
polyoxometalate-based hybrids prepared from choline chloride/urea deep eutectic
mixture at room temperature. Inorg Chem Commun 2010; 13: 972-975.
119
Wang, W.G., Lyons, D.W., Clark, N.N., Gautam, M., Norton, P.M., 2000.
Emissions from nine heavy trucks fueled by diesel and biodiesel blend without
engine modification. Environ. Sci. Technol. 34, 933-939.
Xue H, Verma R, Shreeve JM. Review of ionic liquids with fluorine-
containing anions. J Fluorine Chem 2006; 127: 159-176.
Y. Guo, D.Y.C. Leung, An important affecting factor in biodiesel production:
intensity of mixing, Proc. 29th Annual Conference of the Solar Energy Society of
Canada Inc. 21–25 Aug, The University of Waterloo, Canada. CD-ROM, (2004).
Yue C, Fang D, Liu L, Yi TF. Synthesis and application of task-specific ionic
liquids used as catalysts and/or solvents in organic unit reactions. J Mol Liq 2011;
163: 99-121.
Zhang J, Zhang L, Jia L. Variables affecting biodiesel production from
zanthoxylum bungeanum seed oil with high free fatty acids. Ind Eng Chem Res
2012; 51: 3525-3530.
Zhang Q, De Oliveira Vigier K, Royer S, Jerome F. Deep eutectic solvents:
syntheses, properties and applications. Chem Soc Rev 2012; 41: 7108-7146.
120
7 APPENDICES
APPENDIX A
List of Achievements
Patents
1) Invention Title: A Method for Producing Biodiesel from crude plant-
derived oil using deep eutectic solvent
Filing Number: PI No: PI 2012700963, Filing Date: 20/11/2012.
Publications (Published and accepted papers)
1) Bioresource Technology (Impact Factor 4.980).Q1
Adeeb Hayyan, Farouq S. Mjalli, Mohd Ali Hashim, Maan Hayyan, Inas M.
AlNashef, Saeed M. Al-Zahrani, Mohammed A. Al-Saadi. (2011). Ethanesulfonic
acid-based esterification of industrial acidic crude palm oil for biodiesel
production. Bioresource Technology 102 (2011) 9564–9570. (ISI-Cited Publication/ Elsevier).
2) Chemical Engineering Science (Impact Factor 2.431)Q1
(Accepted)
Adeeb Hayyan, Mohd Ali Hashim, Farouq S. Mjalli, Maan Hayyan, Inas M.
AlNashef. A Novel Phosphonium-Based Deep Eutectic Catalyst for Biodiesel
Production from Low grade Crude Palm Oil. (ISI-Cited Publication/ Elsevier).
3) Thermochimica Acta (Impact Factor 1.805)Q2
Adeeb Hayyan, Farouq S. Mjalli, Inas M. AlNashef, Talal Al-Wahaibi, Yahya M.
Al-Wahaibi, Mohd Ali Hashim. Fruit sugar-based deep eutectic solvents and their
physical properties. Thermochimica Acta 541 (2012) 70– 75. (ISI-Cited
Publication/ Elsevier).
4) Chemical Papers (Impact Factor 1.096)Q3
121
Adeeb Hayyan, Farouq S. Mjalli, Mohamed E.S. Mirghani, Mohd Ali
Hashim, Maan Hayyan, Inas M. AlNashef, Saeed M. Al-Zahrani,. (2011).
Palm Oil Acidity Treatment for Fatty Acid Methyl Ester Production,
Chemical Papers 66 (1) 39–46 (2012). (ISI-Cited Publication/ Springer).
5) International Journal of Green Energy (Impact Factor: 1.188)Q2
Adeeb Hayyan, Farouq S. Mjalli, Mohd Ali Hashim, Maan Hayyan, Inas M.
AlNashef, Talal Al-Wahaibi, Yahya M. Al-Wahaibi. A Solid Organic Acid
Catalyst for the Pre-treatment of Low Grade Crude Palm Oil and biodiesel
production. International Journal of Green Energy. (ISI-Cited Publication/Taylor &
Francis)Q2.
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