International Journal of Renewable and Sustainable Energy

2014; 3(5): 92-98

Published online September 10, 2014 (http://www.sciencepublishinggroup.com/j/ijrse)
doi: 10.11648/j.ijrse.20140305.12
ISSN: 2326-9715 (Print); ISSN: 2326-9723 (Online)

Production of biodiesel from waste cooking oil and

factors affecting its formation: A review
Alemayehu Gashaw1, *, Abile Teshita2
1
Department of Chemistry, Faculty of Natural and Computational Sciences, Bule Hora University, Bule Hora, Ethiopia
2
Department of Biology, Faculty of Natural and Computational Sciences, Bule Hora University, Bule Hora, Ethiopia

Email address:
alexgashaw@gmail.com (A. Gashaw)

To cite this article:

Alemayehu Gashaw, Abile Teshita. Production of Biodiesel From Waste Cooking Oil and Factors Affecting Its Formation: A Review.
International Journal of Renewable and Sustainable Energy. Vol. 3, No. 5, 2014, pp. 92-98. doi: 10.11648/j.ijrse.20140305.12

Abstract: Growing concern regarding energy resources and the environment has increased interest in the study of
alternative sources of energy. To meet increasing energy requirements, there has been growing interest in alternative fuels
like biodiesel to provide a suitable diesel oil substitute for internal combustion engines. Biodiesels offer a very promising
alternative to diesel oil since they are renewable and have similar properties. It is a promising substitute as an alternative
fuel and has gained significant attention due to the predicted shortness of conventional fuels and environmental concern.
The utilization of liquid fuels such as biodiesel produced from waste cooking oil by transesterification process represents
one of the most promising options for the use of conventional fossil fuels. However, as the biodiesel is produced from
vegetable oils and animal fats, there are concerns that biodiesel feedstock may compete with food supply in the long-term.
Hence, the recent focus rely on using waste cooking oil as the substantial feed stocks for biodiesel production.

Keywords: Transesterification, Waste Cooking Oil, Micro-Emulsion Process, Pyrolysis

price. Used vegetable oil is described as a 'renewable fuel'

1. Introduction as it does not add any extra carbon dioxide gas to the
Today it is very essential to use alternative fuel because atmosphere, as opposed to fossil fuels, which cause
of energy security, environmental concerns and socio- changes in the atmosphere. Vegetable oil from plant sources
economic reasons. Escalating oil prices and depletion of oil is the best starting material to produce biodiesel because
reserves necessitate better alternatives of energy from fossil the conversion of pure triglyceride to fatty acid methyl
fuels. With the rise in concern for pollution caused by fossil ester is high and the reaction time is relatively short. The
fuels such as petroleum, coal and natural gas, alternative most common way to produce biodiesel is by
fuels and renewable sources of energy such as biodiesel are transesterification, which refers to a catalyzed chemical
coming in vogue (Garlapati et al., 2013). Besides, the side reaction involving vegetable oil and an alcohol to yield
effect of petroleum based fuels is that over the years there fatty acid alky estersand glycerol (Thirumarimurugan et al.,
has been a steady increase in the amount of pollution 2012).
produced by these fuels. The use of these energy sources The use of edible vegetable oils and animal fats for
over many years have resulted to the rise in global biodiesel production has recently been of great concern
temperature levels also known as global warming because they compete with food materials. As the demand
(Ogunwole, 2012). for vegetable oils for food has increased tremendously in
Over the last few years biodiesel has gained importance recent years, it is impossible to justify the use of these oils
as an alternative fuel for diesel engines. Manufacturing for fuel use purposes such as biodiesel production.
biodiesel from used vegetable oil is relatively easy and Moreover, these oils could be more expensive to use as fuel.
possesses many environmental benefits. The use of Hence, the contribution of non-edible oils such as jatropha
vegetable oils as frying oils produces significant amounts and soapnut will be significant as a non-edible plant oil
of used oils which may present a disposal problem. Their source for biodiesel production (Arjun et al., 2008).
use for biodiesel production has the advantage of their low The costs of raw materials for biodiesel production
accounts for large percent of the direct biodiesel production
 International Journal of Renewable and Sustainable Energy 2014; 3(5): 92-98 93

costs required. Thus, one way of reducing the biodiesel proposed to be promising alternatives to diesel, as they are
production costs is to use the less expensive raw material produced in rural areas. The oil produced from seeds can
containing fatty acids such as animal fats, non edible oils, provide self employment opportunities (Mulimani et al.,
and waste cooking oils and by products of the refining 2012).
vegetables oils (Ogunwole, 2012). Alnuami (2014) This paper reviews the technologies vital for production
compares the cost of biodiesel production based on the of biodiesel starting with the direct use or blending of oils,
materials used. It can be seen that amongst the four continuing with micro emulsion and pyrolysis and finishing
materials such as palm oil, jatropha oil, soya bean oil and with an emphasis on the current process of choice,
waste cooking oil, waste cooking oil can be seen as the transesterification. Besides, it deals with the factors
cheapest and most economical raw material for biodiesel affecting biodiesel production process such as temperature,
production. reaction time, methanol to oil molar ratio, type and amount
However, production of biodiesel from edible oils of catalyst, stirring rate and free fatty acid and moisture
competes with the use of those oils as food resource for content.
human being. Thus, finding cheaper and non edible oils for
biodiesel production is an important target. Therefore, some 2. Waste/Used Cooking Oil
non edible oils and frying oils have been gained more
attention as feedstocks for biodiesel production. However, The feedstock coming from waste vegetable oils or
oils of higher free fatty acid (FFA) content cannot be commonly known as waste cooking oils is one of the
transesterified in the presence of an alkaline base catalyst alternative sources among other higher grade or refine oils.
for it leads to catalyst deactivation and soap formation. As a Waste cooking oil is easy to collect from other industries
result, the FFA content should be reduced A dual step such as domestic usage and restaurant and also cheaper
transesterification namely acid base transesterification than other oils (refine oils). Hence, by using these oils as
(ABTE) was used to reduce the high FFA contents of oils or the raw material, we can reduce the cost in biodiesel
fats. The oil is pretreated with an acid dissolved in production. The advantages of using waste cooking oils to
methanol, where as the second step is base catalyzed produce biodiesel are the low cost and prevention of
transesterification in which oil reacts with methanol in the environment pollution. These oils need to be treating before
presence of an alkaline catalyst to form ester and glycerol dispose to the environment to prevent pollution. Due to the
(Fadhil et al., 2012). high cost of disposal, many individuals dispose waste
Biodiesel can be defined as the alkyl monoesters of fatty cooking oils directly to the environment especially in rural
acids from vegetable or animal fats. It can be used as an area. So that, the use of waste cooking oils is an effective
alternative for petro diesel for it is renewable, non toxic and way to reduce the cost of biodiesel production (Arifin,
biodegradable fuel (Fadhil et al., 2012). As an alternative 2009).
fuel, it has many advantages as it is derived from a Used cooking oil has sufficient potential to fuel the
renewable, domestic resource, thereby relieving compression ignition engines. The kinematic viscosity of
dependence on petroleum fuel trade in. It is biodegradable used cooking oil (UCO) is about 10 times greater, and its
and nontoxic when compared to petroleum based diesel, density is about 10% higher than that of mineral diesel.
biodiesel has a more favorable combustion emission profile, These properties play vital role in the combustion; therefore
such as low emissions of carbon monoxide, particulate these must be modified prior to the use of UCO in the
matter and unburned hydrocarbons. Carbon dioxide engine. Many techniques have been developed to reduce
produced by combustion of biodiesel can be recycled by the kinematic viscosity and specific gravity of vegetable
photosynthesis, thus minimizing the impact of biodiesel oils, which include pyrolysis, emulsification, leaning and
combustion on the greenhouse effect. Biodiesel has a transesterification. Among these techniques,
relatively high flash point, which makes it less volatile and transesterification is the hot favorite. This is because of the
safer to transport or handle than petroleum diesel. Engine fact that this method is relatively easy, carried out at normal
wear and long engine life are advantages that can be conditions, and gives the best conversion efficiency and
provided by biodiesel as it does have lubricating properties. quality of the converted fuel (Shahid et al., 2012).
Therefore, use of biodiesel is being grown vividly during
the last years (Ogunwole, 2012). 3. Biodiesel
Diesel engines are widely used for different application
in industrial power plants, transportation, agriculture etc. Biodiesel is increased attention as an alternative, non-
Despite these advantages, the environmental pollution toxic, biodegradable, and renewable diesel fuel. Biodiesel
caused by diesel engines becomes a major concern is usually produced by the transesterification of vegetable
throughout the world. Diesel engines produce smoke, oil or animal fat with short chain alcohol such as methanol
particulate matter, oxides of nitrogen (NOX), oxides of or ethanol. It has higher oxygen content than petroleum
carbon (CO & CO2) and unburnt hydrocarbon. Several diesel and its use in diesel engines have shown great
alternative fuels have been studied to either substitute reductions in emission of particulate matter, carbon
diesel fuel partially or completely. Vegetable oils are monoxide, sulfur, polyaromatics, hydrocarbons, smoke and
94 Alemayehu Gashaw and Abile Teshita: Production of Biodiesel From Waste Cooking Oil and Factors Affecting Its Formation:
A Review

noise. In addition, burning of vegetable oil based fuel does variety of small molecules. The pyrolysis of vegetable oil
not contribute to net atmospheric CO2 levels because such to produce biofuels has been studied and found to produce
fuel is made from agricultural materials which are produced alkanes, alkenes, alkadienes, aromatics and carboxylic
via photosynthetic carbon fixation (Sukjit and Punsuvon, acids in various proportions. The equipment for thermal
2013). cracking and pyrolysis is expensive for modest biodiesel
production particularly in developing countries.
4. Process of Synthesizing Biodiesel Furthermore, the removal of oxygen during the thermal
processing also removes any environmental benefits of
There are different processes which can be applied to using an oxygenated fuel. Another disadvantage of
synthesize biodiesel such as direct use and blending, micro pyrolysis is the need for separate distillation equipment for
emulsion process, thermal cracking process and the most separation of the various fractions. Also the product
conventional way is transesterification process. obtained is similar to gasoline containing sulphur which
makes it less ecofriendly (Parawira, 2010). Pyrolytic
4.1. Direct Use and Blending chemistry is difficult to characterize because of the variety
The direct use of vegetable oils in diesel engine is not of reaction path and the variety of reaction products that
favorable and problematic because it has many inherent may be obtained from the reaction occur. The pyrolyzed
failings. Even though the vegetable oils have familiar material can be vegetable oils, animal fats, natural fatty
properties as biodiesel fuel, it required some chemical acids and methyl esters of fatty acids. The first pyrolysis of
modification before can be used into the engine. It has only vegetable oil was conducted in an attempt to synthesize
been researched extensively for the past couple of decades, petroleum from vegetable (Arifin, 2009).
but has been experimented with for almost hundred years. 4.4. Transesterification
Although some diesel engine can run pure vegetable oils,
turbocharged direct injection engine such as trucks are The most common way to produce biodiesel is the
prone to many problems. Energy consumption with the use transesterification method, which refers to a catalyzed
of pure vegetable oils was found to be similar to that of chemical reaction involving vegetable oil and alcohol to
diesel fuel. For short term use, ratio of 1:10 to 2:10 oil to yield fatty acid alkyl esters (i.e., biodiesel) and glycerol.
diesel has been found to be successful (Arifin, 2009). The reaction requires a catalyst, usually a strong base, such
as sodium and potassium hydroxide or sodium methylate. A
4.2. Micro-Emulsion Process catalyst is usually used to improve the reaction rate and the
The problem of the high viscosity of vegetable oils was yield. Since the reaction is reversible, excess alcohol is
solved by micro-emulsions with solvents such as methanol, used to shift the equilibrium to the product side. Especially
ethanol, and 1-butanol. Micro-emulsion is defined as a methanol is used as alcohol because of its low cost and its
colloidal equilibrium dispersion of optically isotropic fluid physical and chemical advantages. Methanol can quickly
microstructures with dimensions generally in the 1-150 nm react with vegetable oil and NaOH can easily dissolve in it.
range formed spontaneously from two normally immiscible To complete a transesterification reaction stoichiometrically,
liquids and one or more ionic or non-ionic amphiphiles a 3:1 molar ratio of alcohol to triglycerides is necessary. In
(Arifin, 2009; Parawira, 2010). practice, the ratio needs to be higher to drive the
The components of a biodiesel micro-emulsion include equilibrium to a maximum ester yield (Sarıbıyık et al.,
diesel fuel, vegetable oil, alcohol, and surfactant and cetane 2012; Antony Raja et al., 2011).
improver in suitable proportions. Alcohols such as The triglycerides are reacted with a suitable alcohol
methanol and ethanol are used as viscosity lowering (Methyl, Ethyl, or others) in the presence of a catalyst
additives, higher alcohols are used as surfactants and alkyl under a controlled temperature for a given length of time.
nitrates are used as cetane improvers. Microemulsions can The final products are Alkyl esters and Glycerin. The Alkyl
improve spray properties by explosive vaporisation of the esters, having favorable properties as fuels for use in CI
low boiling constituents in the micelles. Micro-emulsion engines, are the main product and the Glycerin, is a by-
results in reduction in viscosity increase in cetane number product. The chemical reaction of the tri-glyceride with
and good spray characters in the biodiesel. However, methyl alcohol is shown below. With higher alcohols the
continuous use of micro-emulsified diesel in engines causes chemical equation would change correspondingly
problems like injector needle sticking, carbon deposit (Jaichandar and Annamalai, 2011).
formation and incomplete combustion (Parawira, 2010).

4.3. Thermal Cracking (Pyrolysis)

Pyrolysis can be defined as the conversion of one

substance into another by means of heat in the absence of
air (or oxygen) or by heat in the presence of a catalyst
which result in cleavage of bonds and formation of a Figure 1. General equation for transesterification of triglycerides.
 International Journal of Renewable and Sustainable Energy 2014; 3(5): 92-98 95

5. Biodiesel Production Processes material (Garlapati et al., 2013).

Biodiesel derived from biological resources is a 5.5. Biodiesel Washing

renewable fuel, which has drawn more and more attention
recently. A fatty acid methyl ester is the chemical After transesterification the upper ester layer may
composition of biodiesel. Transesterification is widely used contain traces of NaOH, methanol and glycerol. Since the
for the transformation of triglyceride into fatty acid methyl remaining unreacted methanol in the biodiesel has
ester. The manufacturing process is based on the safety risks and can corrode engine components, the
transesterification of triglycerides by alcohols to fatty acid residual catalyst (NaOH) can damage engine components,
methyl esters, with glycerol as a byproduct. The base and glycerol in the biodiesel can reduce fuel lubricity and
catalyzed production of biodiesel generally has the cause injector coking and other deposits. These being
following processes. water soluble is removed by washing (4 -6 times) the
biodiesel with water maintained at 40-50ºC. Washing is
5.1. Mixing of Alcohol and Catalyst carried out by spraying hot water over the biodiesel;
precautions were taken to avoid soap formation (Mulimani,
This typical process is mainly done by mixing alkali et al., 2012). The washed biodiesel needs drying in order to
hydroxide (commonly potassium hydroxide and sodium remove trace impurities. In some processes washing step is
hydroxide) with common alcohols (methanol and ethanol) not necessary depending on the quality of biodiesel
in the mixer with standard agitator to facilitate the mixing. produced (Garlapati et al., 2013).
Alkali hydroxide is dissolved in the alcohol to produce After the completion of washing process the biodiesel
alkoxide solution (Garlapati et al., 2013). may contain some traces of water. Biodiesel is heated to
5.2. Chemical Reaction 110 0C to remove the trapped traces of water (for drying)
(Mulimani, et al., 2012).
The alcohol and catalyst mixture is then charged into a
Vegetable oil
closed reaction vessel and the oil is added. The reaction
system is totally closed to the atmosphere to prevent the
loss of alcohol, since it easily vaporizable. The reaction Heating on Magnetic Stirrer (65-75oC)
mixture is kept just near the boiling point of the alcohol to
Alcohol(CH3OH)
speed up the reaction. Excess alcohol is normally used to + Transesterification
ensure total conversion of the oil to its esters as there is no Catalyst(NaOH)
problem of recovering of the alcohol for later use after Settling down Glycerin
recycling.

5.3. Separation Biodiesel Washing Purification

After the reaction is completed, there exists glycerol and Soap/Pears/ Candle
Heating
biodiesel formation. Both have a significant amount of the
(110oC)
excess alcohol that was used in the reaction which is in
need of being recovered. The reacted mixture is sometimes
Pure Biodiesel
neutralized at this step if the basic media that is caused by
alkali hydroxide is occurred. The glycerol phase is much Figure 2. Flow chart of Biodiesel production process (Mulimani, et al.,
denser than biodiesel phase, making biodiesel to be floated. 2012).
The two products can be separated by gravity using settling
vessel. The glycerol is drawn off at the bottom of the 6. Factors Affecting Biodiesel
settling vessel and biodiesel is drawn off at the top. In some
cases, a centrifuge is used to separate the two materials Production
faster by screening both phases (Garlapati et al., 2013).
The process of transesterification brings about drastic
5.4. Alcohol Removal change in viscosity of the vegetable oil. The high viscosity
component, glycerol, is removed and hence the product has
After the glycerol and biodiesel phases have been low viscosity like the fossil fuels. The biodiesel produced is
separated, the excess alcohol in each phase is removed with totally miscible with mineral diesel in any proportion. Flash
a flash evaporation process or by distillation commonly. point of the biodiesel is lowered after transesterification
But currently extractive distillation can instead be used to and the cetane number is improved. The yield of biodiesel
fasten the process and to be more economical. On the other in the process of transesterification is affected by several
hand, the alcohol is removed and the mixture neutralized process parameters which include; presence of moisture
before the glycerol and esters have been separated to and free fatty acids (FFA), reaction time, reaction
prevent the effect of basic media inside the reactor. After temperature, catalyst and molar ratio of alcohol and oil
the alcohol is being recovered it is used as main raw (Parawira, 2010).
96 Alemayehu Gashaw and Abile Teshita: Production of Biodiesel From Waste Cooking Oil and Factors Affecting Its Formation:
A Review

The main factors affecting the transesterificationare introducing an excess amount of methanol to shift the
molar ratio of alcohol to oil, amount and catalyst type, equilibrium to the right hand side (Anitha and Dawn, 2010).
reaction time, reaction temperature, stirring rate, presence Methanol, ethanol, propanol, butanol and amyl alcohol
of free fatty acids and moisture (Mulimani et al., 2012; can be used in the transesterification reaction, amongst
Highina, et al., 2012). these alcohols methanol is applied more frequently as its
cost is low and it is physically and chemically
6.1. Temperature advantageous (polar and shortest chain alcohol) over the
Reaction temperature is the important factor that will other alcohols. In contrast, ethanol is also preferred alcohol
affect the yield of biodiesel. For example, higher reaction for using in the transesterification process compared to
temperature increases the reaction rate and shortened the methanol since it is derived from agricultural products and
reaction time due to the reduction in viscosity of oils. is renewable and biologically less offensive in the
However, the increase in reaction temperature beyond the environment. The effect of volumetric ratio of methanol
optimal level leads to decrease of biodiesel yield, because and ethanol to oil was studied. Results exhibit that highest
higher reaction temperature accelerates the saponification biodiesel yield is nearly 99.5% at 1:6 oil/methanol. In
of triglycerides (Mathiyazhagan and Ganapathi, 2011) and comparison, biodiesel yield using methanol continuously
causes methanol to vaporize resulting in decreased yield increases with the raise of methanol molar ratio (Hossain
(Anitha and Dawn, 2010). and Boyce, 2009).
Usually the transesterification reaction temperature 6.4. Type and Amount of Catalyst
should be below the boiling point of alcohol in order to
prevent the alcohol evaporation. The range of optimal Biodiesel formation is also affected by the concentration
reaction temperature may vary from 50°C to 60°C depends of catalyst. Most commonly used catalyst for biodiesel
upon the oils or fats used (Mathiyazhagan and Ganapathi, production is sodium hydroxide (NaOH) or Potassium
2011). Therefore, the reaction temperature near the boiling hydroxide (KOH) (Mathiyazhagan and Ganapathi, 2011).
point of the alcohol is recommended for faster conversion The type and amount of catalyst required in the
by various literatures. At room temperature, there is up to transesterification process usually depend on the quality of
78% conversion after 60 minutes, and this indicated that the the feedstock and method applied for the transesterification
methyl esterification of the FFAs could be carried out process. For a purified feedstock, any type of catalyst could
appreciably at room temperature but might require a longer be used for the transesterification process. However, for
reaction time. In butyl esterification, however, temperature feedstock with high moisture and free fatty acids contents,
had stronger influence. Temperature increases the energy of homogenous transesterification process is unsuitable due to
the reacting molecules and also improves the miscibility of high possibility of saponification process instead of
the alcoholic polar media into a non-polar oily phase, transesterification process to occur.
resulting in much faster reactions (Ogbu and Ajiwe, 2013). The yield of fatty acid alkyl esters generally increases
with increasing amount of catalyst. This is due to
6.2. Reaction Time availability of more active sites by additions of larger
The increase in fatty acid esters conversion observed amount of catalyst in the transesterification process.
when there is an increase in reaction time. The reaction is However, on economic perspective, larger amount of
slow at the beginning due to mixing and dispersion of catalyst may not be profitable due to cost ofthe catalyst
alcohol and oil. After that the reaction proceeds very fast. itself. Therefore, similar to the ratio of oil to alcohol,
However the maximum ester conversion was achieved optimization process is necessary to determine the optimum
within < 90 min. Further increase in reaction time does not amount of catalyst required in the transesterification
increase the yield product i.e. biodiesel/mono alkyl ester. process (Kansedo, 2009; Jagadale and Jugulkar, 2012).
Besides, longer reaction time leads to the reduction of end 6.5. Mixing Intensity
product (biodiesel) due to the reversible reaction of
transesterification resulting in loss of esters as well as soap Oils and alcohols are not totally miscible, thus reaction
formation (Mathiyazhagan and Ganapathi, 2011; Jagadale can only occur in the interfacial region between the liquids
and Jugulkar, 2012). and transesterification reaction is a moderately slow
process. So, Mixing is very important in the
6.3. Methanol to Oil Molar Ratio transesterification process, adequate mixing between these
One of the most important parameters affecting the yield two types of feedstock is necessary to promote contact
of biodiesel is the molar ratio of alcohol to triglyceride. between these two feed stocks, therefore enhance the
Stoichiometrically 3 moles of alcohol and 1 mole of transesterification reactions to occur. Mechanical mixing is
triglyceride are required for transesterification to yield 3 commonly used in the transesterification process. The
moles of fatty acid methyl/ethyl esters and 1 mole of intensity of the mixing could be varied depending on its
glycerol is used. It is varied from 5.6 – 7.8:1 for both the necessity in the transesterification process. In general, the
catalyst systems. Biodiesel yield could be elevated by mixing intensity must be increased to ensure good and
 International Journal of Renewable and Sustainable Energy 2014; 3(5): 92-98 97

uniform mixing of the feedstock. When vegetable oils with 7. Conclusion

high kinematic viscosity are used as the feedstock,
intensive mechanical mixing is required to overcome the With exception of hydropower and nuclear energy, the
negative effect of viscosity to the mass transfer between oil, major part of all energy consumed worldwide comes from
alcohol and catalyst (Jagadale and Jugulkar, 2012; Kansedo, petroleum, charcoal and natural gas. However, these
2009). sources are limited, and will be exhausted in the near future.
Agitation speed plays an important role in the formation Thus, Biodiesel is an alternative and renewable fuel for
of end product (mono alkyl ester or biodiesel), because diesel engines and has become more attractive in recent
agitation of oil and catalyst mixture enhances the reaction. times. The catalysts used in the production of biodiesel are
For example the mixing intensities chosen were 200 rpm, acids, bases and enzymes. Transesterification is a
400 rpm, 600 rpm and 800 rpm for 60 min while other commonly employed method to reduce the viscosity during
parameters were kept constant. At 400 rpm higher the production of biodiesel. The purpose of this method is
conversion of end product were obtained. Because, lower to reduce the viscosity of oil or fat using acid or base
stirring speed shows lower product formation. On the other catalyst in the presence of methanol or ethanol. However,
hand higher stirring speed favors formation of soap. This is the biodiesel production by transesterification is strongly
due to the reverse behavior of transesterification reaction affected by molar ratio of alcohol, reaction temperature,
(Mathiyazhagan and Ganapathi, 2011). reaction time and catalyst concentration. The main
advantage in biodiesel usage is attributed to lesser exhaust
6.6. Free Fatty Acid and Moisture Content emissions in terms of carbon monoxide, hydrocarbons and
particulate matter. Hence, the paper concentrates on the
The free fatty acid and moisture content are the key development of economically viable as well as ecofriendly
parameters for determining the viability of vegetable oils to substrates such as waste cooking oil for biodiesel
be used in transesterification process. Presence of moisture production and briefly discusses the factors that will affect
content in the oil increases the amount of free fatty acids. the biodiesel production.
To carry out this reaction to completion, less than 3% free
fatty acid content in oils is needed.
Base-catalyzed transesterification reaction requires water
free and low acid value (< 1) raw materials for biodiesel
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