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Prospective ecofuel feedstocks for sustainable production 95

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by sunflower oil methyl esters include a kinematic viscosity of 4.3mm /s, an acid
value 0.3mg/KOH, a cetane number of 46.9, and cloud point of 1°C [25].

4.2.1.2 Potential edible oils
The following are the potential edible oils used for the production of biodiesel.

Rice bran oil (Oryza sativum)
Rice bran (Oryza sativum), which is treated as agricultural waste in rice-producing
countries, forms the source from which the crude rice bran oil is extracted. It is con-
sidered an alternative low-cost feedstock for the production of biodiesel when com-
pared to other feedstocks such as soybean, canola, rapeseed, and sunflower oils. Only
a small portion (<10%) of crude rice bran oil could be converted to edible oil due to
the difficulties in the refinement process because it contains a high content of free fatty
acids [26]. The fatty acid profile of inedible rice bran oil shows that the oil is high
in oleic acid (43.1wt%), linoleic acid (33.2wt%), and palmitic acid (18.8wt%);
the other fatty acids present are myristic acid (0.4–1.0wt%), stearic acid
(1.0–3.0wt%), arachidic acid (<2.5wt%), and linolenic acid (0.5–1.0wt%) [9].As
per the work carried out by Sinha et al. [27], maximum conversion of crude rice
bran oil to its corresponding ethyl esters has been obtained at a reaction temperature
of 55°C for a methanol to oil molar ratio of 9:1 in a reaction time of 60min using
0.75% (wt of oil) NaOH catalyst. The properties of methyl esters of rice bran oil
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include a kinematic viscosity of 5.29mm /s, a calorific value of 42.2MJ/kg, a cetane
number of 63.8, a cloud point of 9°C, and pour point of 2°C [27].

Sesame oil (Sesamum indicum)
Sesame (Sesamum indicum) belongs to the family Pedaliaceae. It is an annual herba-
ceous flowering plant that has also been adapted to semiarid climates. It is cultivated
in many regions of the world as an important oilseed crop. About 44–58wt% of oil is
present in sesame seeds [17]. The sesame oil contains antioxidant substances such as
sesamolin, sesamine, and sesamol, because of which the oil is quite stable. The fatty
acid profile of sesame oil shows the presence of linoleic acid (42.9–54wt%), oleic acid
(31.6–42wt%), palmitic acid (7.2–9.7wt%), and stearic acid (3.8–5.6wt%) [28].
Saydut et al. [29], obtained the maximum conversion of 74% of crude sesame oil
to its corresponding ester for a methanol to oil ratio of 6:1 at 60°C reaction temper-
ature using 0.6% (wt of oil) NaOH as a catalyst in a reaction time of 2h. The properties
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of methyl esters of sesame oil include a kinematic viscosity of 4.2mm /s, a cetane
number of 50.48, a cloud point of 6°C, and a pour point of 4°C [29].
Coconut oil (Cocos nucifera)
Coconut (Cocos nucifera) belongs to the Arecaceae family and is a perennial species
that is widely distributed in the tropics. Typica Nar (tall variety) and Nana Griff
(Dwarf variety) are the two basic types of coconut trees. A hybrid of these varieties
is also available. High oil yield has been obtained from tall and hybrid varieties and the
dwarf variety has a high production of coconut water. Because of the high oil content