Page 124 - Advances in Eco-Fuels for a Sustainable Environment

96 Advances in Eco-Fuels for a Sustainable Environment

in coconut, it became a candidate for the production of biodiesel. Copra, the dried
flesh of the nut, is used for extracting coconut oil. Copra has 58–65wt% of oil content
[30]. Coconut oil starts solidifying at a temperature below 22°C and below 14°Cit
cannot flow at all, thus resulting in a drawback for the use of coconut oil in engines.
Caproic acid (0–0.8wt%), caprylic acid (5.0–9.0wt%), capric acid (6.0–10.0wt%),
lauric acid (44–52wt%), myristic acid (13–19wt%), palmitic acid (8–11wt%), stearic
acid (1–3wt%), arachidic acid (0–0.5wt%), oleic acid (5–8wt%), linoleic acid
(0–0.5wt%), and palmitoleic acid (2.5wt%) are the main fatty acids in coconut oil
[12]. As per Kumar et al. [31], the conversion of around 94% has been obtained from
crude coconut oil for a methanol to oil ratio of 8:1 at a reaction temperature of 60°Cin
a reaction time of 120min using 1% (wt of oil) KOH as a catalyst via ultrasound-
assisted transesterification reaction. The properties of ethyl esters of coconut oil
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include a kinematic viscosity of 2.61mm /s, an acid value of 0.17mgKOH/g, a cetane
number of 51, and a cold filter plugging point of 5°C [31].

Corn oil (Zea mays)
Corn (Zea mays) cannot be grown specifically for biodiesel production. It is mainly
grown in the United States for its starch and protein content because it is a starch crop.
It is not possible to produce a grade of oil from corn suitable enough for the production
of biodiesel by the extraction process. Corn is used for the production of ethanol by the
fermentation process [12]. During the production of ethanol by the fermentation pro-
cess, dried distiller’s grains (DDG) are produced as a byproduct, which forms the
source of corn oil, and it contains 8–10wt% corn oil. The free fatty acid (FFA) content
in corn oil extracted from DDG is around 7.0wt%, thus making a need for an alternate
method or acid-catalyzed pretreatment for the high yield of corresponding methyl
esters [17]. The oil content in DDG is around 48wt% and the fatty acids present in
corn oil are caprylic acid (4wt%), capric acid (7wt%), myristic acid (0.2–1.0wt%),
palmitic acid (8–12wt%), stearic acid (2–5wt%), oleic acid (19–49wt%), and linoleic
acid (34–62wt%) [12]. As per the work carried out by El Boulifi et al. [32], the max-
imum conversion of 98.75% of corn oil to its corresponding methyl esters has been
obtained with a methanol to oil molar ratio of 6:1 at a reaction temperature of
55.6°C in a reaction time of 60min using 1.18% (wt of oil) KOH catalyst. The prop-
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erties of methyl esters of corn oil include a kinematic viscosity of 5.82mm /s, an acid
value of 0.7mgKOH/g, a cloud point of 4°C, and a pour point of 6°C under normal
oxygen atmosphere [32].

Cottonseed oil (Gossypium hirsutum)
Cotton (Gossypium hirsutum) belongs to the Malvaceae family and is a herbaceous
annual plant that is harvested 3 months per year. The widely consumed and industri-
ally produced oldest vegetable oil in Brazil is cottonseed oil. In Brazil, cotton oil is
the third feedstock used for the production of biodiesel after soybean oil and beef tal-
low. The oil content in cottonseed is in the range of 18–25wt% and approximately
361kg/ha oil yield is obtained, resulting in the requirement of large planted areas
to obtain a small amount of oil [30]. The fatty acids present in cotton oil are myristic