This document summarizes the process of manufacturing biodiesel from waste cooking oil. It involves analyzing the fatty acid content of the waste oil, performing a trans-esterification process using methanol and sodium hydroxide as catalyst to convert the oil to biodiesel and glycerol, separating the biodiesel and glycerol, washing the biodiesel, and testing the biodiesel properties including density, viscosity, copper corrosion, and flash point. Using waste cooking oil is beneficial as it reduces biodiesel production costs compared to using edible plant oils and helps manage waste oil.

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R.V COLLEGE OF ENGINEERING,BANGALORE
MANFUCTURE OF BIODIESEL FROM WASTE
COOKING OIL By – Asheesh Padiyar &
Manas Likhit
Department of Chemical
Engineering

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Keywords: Waste cooking oil, alternate energy, biodiesel.
1. Introduction
Increasing uncertainty about global energy production and supply, environmental concerns due to
the use of fossil fuels, and the high price of petroleum products are the major reasons to search for
alternatives to petro diesel. It is being claimed that the global supply of oil and natural gas from the
conventional sources is unlikely to meet the growth in energy demand over the next 25 years. In this
perspective, considerable attention has been given towards the production of biodiesel as a diesel
substitute. Moreover, biodiesel fuel has become more attractive because of its environmental benefits
, due to the fact that plants and vegetable oils and animal fats are renewable biomass sources.
Compared to petroleum diesel, biodiesel has lower emission of pollutants and enhances the engine
Lubricity and contributes to sustainability. Biodiesel has a higher Cetane number than diesel fuel, no
aromatics, no sulfur, and contains 10–11%oxygen by weight.
Use of neat (unprocessed) vegetable oils in the compression ignition engines is reported to cause
several problems due to its high viscosity. Biodiesel which is accepted as an attractive alternative
fuel, is prepared by trans-esterification of vegetable oils and animal fats with an alcohol in presence of
a catalyst. However, the land use for production of edible oil for biodiesel feedstock competes with the
use of land for food production. Moreover, the price of edible plant and vegetable oils is usually higher
thanpetro-diesel. The use of waste cooking oil as biodiesel feedstock reduces the cost of biodiesel
production since the feedstock costs constitutes approximately 70-95% of the overall cost of
biodiesel production. Hence, the use of waste cooking oils and non-edible oils should be given
higher priority over the edible oils as biodiesel feedstock.

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1.1. Potential of waste cooking oil as a feedstock for biodiesel source:
Huge quantities of waste cooking oils and animal fats are available throughout the world, especially
in the developed countries. Management of such oils and fats pose a significant challenge because of
their disposal problems and possible contamination of the water and land resources. Even though some
of this waste cooking oil is used for soap production, a major part of it is discharged into the
environment.
Diesel fuel consumption significantly contributes to the formation of greenhouse gases (GHG) and
other global pollutant emissions. Petroleum diesel is also the major source
for the emission of NOx, SOx, CO, particulate matter and volatile organic compounds (VOCs).
Emission of such pollutants not only has negative impacts to the global environment but also severe
impacts in human health due to their persistence in the environment.
The use of waste cooking oil as a biodiesel source has a potential to reduce CO2, particulate matter
andother greenhouse gases as the carbon contained in biomass-derived fuel is largely biogenic and
renewable.
Waste cooking oil, which is otherwise wasted, is one of the most economical choices to produce
biodiesel. Since one of the major concerns on biodiesel production is the price of feedstock, utilization
of waste cooking oil significantly enhances the economic viability of biodiesel production.

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Procedure:
2.1. Fatty Acid Content Analysis
Fatty acid contents are the major indicators of the properties of biodiesel. Usually the acids that are
present in vegetable oil include oleic acid linoleic acid, linolenic acid, palmitic acid, stearic acid,
ecosenoic acid.
For effective conversion, the FFA content must be lesser than 4%. If found greater than 4%
esterification is carried out to decrease the FFA content below 4%.
2.1.1 Titration process:
Sodium hydroxide was used as catalyst in this experiment. The amount of catalyst has an impact in
the conversion of esters during the transesterificationprocess. The titration was carried out in order to
determine the optimum amount of catalyst concentrate for efficient transesterification.
First, 0.1 N NaOH was taken in a 50 ml burette. To a clean 250 ml conical flask , 50 ml isopropyl
alcohol was added and 2-3 drops of NaOH from the burette was added to neutralize isopropyl alcohol.
To this solution 10 g of oil was added. The solution was stirred well and heated to 60⁰ C. The solution
was cooled under tap water and 2-3 drops of Phenolphthalein indicator was added. The color of the
solutionobtained was milky yellow. Then it was titrated against 0.1 N NaOH. At the end point the color
changes to red.

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2.1.2 Calculation:
FFA content in our sample was found to be 0.7896 g
2.2 Trans- esterification process:
One liter of sample oil was taken in a 3 neck flask and heated to 60⁰ C. The sample was continuously
stirred using magnetic stirrer for uniform distribution of heat throughout the sample.
When the temperature of the sample reaches 60⁰ C methoxidecatalyst was added to the flask. The
catalyst consisted of 300 ml methanol and NaOH. The amount of NaOH depends on the FFA content.
The catalyst was added only when temperature reached 60⁰ C. The oil was made to react for 1.5 hours.
The end of the reaction was marked by the slight separation of the two liquids (impure biodiesel and
glycerol).

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2.3 Separation Process:
The contents of the 3 neck flask were transferred to a separating funnel. The separating funnel was
kept undisturbed for 3-4 hours, allowing the liquids to separate. Glycerol being denser than the bio-
diesel , occupied the lower portion of the separating funnel bio-diesel being the top layer. Glycerol was
then separated and transferred to another flask. It can be noted that glycerol is one of the most
important components in soap making and hence the glycerol obtained could be used for the same
purpose. The liquid left behind is nothing but the impure bio diesel which is further purified.
2.4. Biodiesel Washing
Washing of final ester products is a very important activity during biodiesel processing. The ester
was washed several times through the distilled water creating fine mist from the top through a spray.
The washing of the biodiesel is repeated till the pH of the water reaches 7. Fine mist washing, which
causesless agitation, results in less soap formation. Washing can improved by using hot wash water of
50⁰-60⁰C.
3. Tests:
The Indian Oil Corporation conducts more than 250 tests to test the quality of the fuel. Of these 4
primary tests were conducted. Once the convincing results are obtained the fuel is subjected to further
analysis and tests.
3.1. Density test:
Density of the biodiesel was obtained by using hydro-meter. Sufficient quantity of bio-diesel was

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taken in a measuring beaker. The hydro-meter was then immersed in the biodiesel and the
corresponding reading was noted.
The density of the biodiesel usually obtained lies between 0.8-0.9 g/cc. The density of the biodiesel
obtained was found to be 0.965 g/cc.
3.2 Viscosity test:
Viscosity of the biodiesel was obtained using viscometer. The viscosity test is conducted at 40⁰ C.
The biodiesel was transferred to a viscometer. The viscometer was submerged into water which was
preheated to 40⁰ C . The time taken for the biodiesel to flow between two marked points in the
viscometertube was found. Using the calibrated values of the viscometer and the time taken for the
flow the viscosity was calculated. The viscosity of the biodiesel obtained was found to have a value of
5.68
3.3 Copper Corrosion test:
The amount of acid content in the biodiesel is tested by this method. The presence of acids in the
fuel leads to corrosion of the various engine parts . The biodiesel was taken in a metallic container and a

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copper strip is dipped in it. The container was heated at 60⁰ C for 3 hours. The heating at 60⁰C was done
to mimic the conditions in the engine parts. After 3 hours the copper strip is taken out and checked for
any corrosion signs. If the corrosion signs are found, it can be concluded that the biodiesel obtained is
too acidic for the engine parts.
The biodiesel that was obtained was not found to be corrosive because the copper strip that was
submerged in the biodiesel had no spots.
3.4 Flash Point test:
This test is used to find out the lowest temperature at which the biodiesel can vaporize to form an
ignitable mixture in air.The biodiesel was taken in a closed container and was progressively heated to
100⁰C. At this point the lid of the container was opened and an ignition source(match stick) was
brought near the lid .If a bright flash is seen then this is the flash point temperature of the volatile
material. If not the temperature is progressively increased to higher temperatures and tested for flash
point.
For ordinary diesel the flash point usually occurs at 60-70⁰ C. It was found that there was there no
flash at 100⁰C, 110⁰C,120⁰ C and 130⁰ C , for the biodiesel obtained, indicating it is less volatile .

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4.Conclusion:
The land use for production of edible oil for biodiesel feedstock competes with the use of land for
food production. Moreover, the price of edible plant and vegetable oils is usually higher than
Petro-diesel. The use of waste cooking oil as biodiesel feedstock reduces the cost of biodiesel
production since the feedstock costs constitutes approximately 70-95% of the overall cost of biodiesel
production. Hence, the use of waste cooking oils and non-edible oils should be given higher priority over
the edible oils as biodiesel feedstock.
The above process provides a cheap effective method for the conversion of waste cooking oil to
Bio-diesel. Although the biodiesel entirely cannot be used to for the normal diesel engines it can be
blend with the ordinary diesel and used. Doing this has two advantages. Firstly it will reduce the
severity of water pollution. And secondly, cuts down the rate at which the fossil fuel is being depleted.
It’s clear that biodiesel that we are producing is not an 100% substitute to the normal diesel but it can
surely extend the time of exhaustion of fossil fuel, giving time for other energy technologies to develop
so that it must be fully efficient and satisfies our increasing energy needs.

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Acknowledgements:
We would like to thank our college R.V College of Engineering ,Bangalore for providing all the
necessary instruments and laboratory equipment’s required for this project. We also thank our guide
Prof. C.Manjunatha who has been with us throughout extending his helping hand.