Abstract
Biodiesel is a biodegradable, environment friendly, renewable and energy efficiency fuel. It is
becoming the most prominent alternative to petro-diesel. Due to current environmental concerns,
quality and properties of biodiesel have to be optimized to remove its limitations. The use of
oxygenates additives have proved to play such important role. The purpose of this research work
was to compare the effects of oxygenates on biodiesel properties such as viscosity, heat content,
density, specific gravity, and flash point, pour and cloud point. Tiger and neem oil were extracted
from tiger and neem seed and were used to produce biodiesel. The properties of produced biodiesel
were studied and compared to ASTM standards. Oxygenates additives (methanol, ethanol and
diethyl ether) were added to the biodiesel at different ratios (10%, 20% and 30%) to study their
effect on the quality of biodiesel produced. The kinematic viscosity of pure Neem Oil Methyl ester
(NOME) and Tiger
Introduction
Depletion of fossil fuels, increasing in greenhouse effects and evolution in energy demands have
led to the search for new alternatives to fossil fuels. Researchers proved that many sources of
fossil-fuels around the world are nearly close to their maximum production. This simply means
that fossil-fossil is not a sustainable source of energy and there is a limited supply of it
(Sivalakshmi, 2011).The only solution to this issue was to look and develop alternatives sources
of energy (biofuel). Among biofuels alternatives, biodiesel was found to be the most effective one.
Many researches have studied on advantages of biodiesel as biofuel, its production and
characterization.
1.1. Biodiesel
Biodiesel is a biodegradable, environment friendly, renewable, energy efficient fuel that is
used as a substitute of fossil fuel to solve the crisis in fossil fuel diminution and environmental
degradation. It is known that biodiesel has ability to be used as pure (Vijayan V, 2013). However,
due to the current concerns on the environment; properties of biodiesel have to be improved in
order to reduce problems related to its fuel properties. Because of this, recent researches are not
only interested in biodiesel production, but maximization of the biodiesel quality and
characteristics.
Therefore, in this project, we will look at how biodiesel properties can be improved. Recent
researches have proved that compounds which contain oxygen in their structure can be used to
improve the properties of biodiesel. Oxygenates are among the compounds with oxygen in their
chemical structure.
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1.2. Biodiesel over fossil fuel
Currently, production of biodiesel is getting much consideration worldwide. This consideration is
due to the fact that it is non-toxic, biodegradable and produces less emission of particulates to the
atmosphere. It was reported that any fatty acid sources such as vegetable oil or animal fat oil can
be used to produce biodiesel (Elkady, 2009).
It was confirmed that biodiesel is more environmental friendly than fossil fuel. Due to the current
issue of climate change, today’s world is more caring on environment. To use biodiesel
effectively, its environmental hazards have to be minimized as much as possible, as well as its heat
content as an alternative source of energy has to be improved. To match these requirements,
oxygenates were found to play such roles (Barminas JT, 2013)
1.3. Tigernut
Tigernut oil is a type of oil extracted from tigernut seed. Tigernut was discovered 400 years
ago and since then it has been used as human consumption and livestock. Tigernut (plant of
Cyperus esculentus) can be found in almost every part of Nigeria. This plant is now cultivated in
Northern Nigeria and it can be found in the markets throughout the year. It is known in Nigeria as
Aya in Hausa, Ofio in Yoruba and Akihausa in Ibo. It can be found in three different varieties
(black, brown and yellow). Yellow variety is the most preferable one because it can be gotten in
bigger size and attractive color. Tigernut has many applications including flavoring agent, in ice
cream making and others. Most importantly, its composition such as high fiber and starch content
makes it to be a good feedstock for biodiesel production. (Gambo, 2014).
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1.3.1. Composition of dried Tigernut
Constituents Yellow variety (%) Brown variety (%)
Moisture 3.50 3.78
Crude Protein 7.15 9.70
Lipid 32.13 35.43
Crude Fibre 6.26 5.62
Carbohydrates 46.99 41.22
Ash 3.97 4.25
Energy (KJ) 1343 1511
Table 1: Composition of dried Tigernut
1.4 Neem seed
Neem oil is type of oil extracted from neem seed. Neem oil is composed of many
biologically active compounds. Neem oil has numerous applications such as in soap making
(Neem soap), making drugs and so on (Vinod Vijayan, 2013).
1.5 Biodiesel production
Biodiesel is produced by the reaction of transesterification. Transesterication is the process
whereby fat or oil reacts with an alcohol in the presence of a base catalyst to form the mixture of
esters and glycerol. The presence of excess alcohol as catalyst drives the production of large
amount of biodiesel. After the production of methyl ester and glycerol, the next step is filtration
where upper layer is collected as methyl ester and lower layer is glycerin. Biodiesel produced
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contains much content of alcohol and base. Therefore, this biodiesel must be washed with hot
water to obtain pure biodiesel (Singh Yadav, 2013)
Figure 1: Schematic of biodiesel production
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The following is the reaction for biodiesel production
1.6. Oxygenates
This project is mainly looking at how biodiesel properties can be improved. Recent
researches have proved that oxygenates can be used to improve the properties of biodiesel.
Oxygenates are among the compounds with oxygen in their chemical structure. These are usually
used as additives to reduce carbon monoxide and soot that is created during the burning of fuel.
Traditionally, in USA oxygenates were used to increase energy efficiency of gasoline because they
have relatively high octane rating. During energy crisis in 1974, Oxygenates such as ethanol and
Methyl-Ter-Butyl ether were used to improve properties of gasoline.
According to American Petroleum Institute, oxygenates have been used to primarily
improve gasoline octane number and to reduce carbon monoxide emission and greenhouse effects.
Several experimental researches have proven that oxygenates improve octane rating of biodiesel
and reduce particulate emissions to the atmosphere. “These studies have proved that this reduction
does not only depend on the oxygen content but also on the molecular structure and the different
oxygen functional groups”.
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1.6.1. Physical properties of oxygenates
The following table illustrates some physical properties of oxygenates
Oxygenates Blending
octane
Blending
RVP
Boiling
point(F)
Energy
content(MBTU/gal)
Oxygen
content
Water
solubility
(%)
Methyl TerButyl
Ether(MTBE)
110 8.0 131 93.5 18.2 4.3
Ethyl TerButyl
Ether(ETBE)
112 4.0 161 96.9 15.7 1.2
Ethanol 115 18 173 76 34.8 Infinite
TBA 100 9.0 181 94.1 21.6 Infinite
Propanol 106 14.0 180 87.4 26.7 Infinite
Butanol 102 5.0 226 95.1 21.6 10
Table 2: Physical properties of oxygenates
By Jose Gomez etal, 2011
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1.7 Aims and significance
The purpose of this research is to develop new alternative source of energy (biofuel). This
research is also designed to upgrade biodiesel by improving its properties (Viscosity, heat content).
Additionally, this project will compensate for energy consumption and protection of environment
by using clean fuels. All these aims will be achieved by using oxygenates as additives to improve
biodiesel properties.
In this project, two different biodiesels are synthesized from different vegetable oil by
solvent extraction method using ethanol as a solvent. First biodiesel is synthesized from tiger oil
and another is synthesized from Neem oil. The research will also look at the essential fuel
properties of biodiesel such as density, flash point, viscosity, and acid number.