Page 127 - Advances in Eco-Fuels for a Sustainable Environment

Prospective ecofuel feedstocks for sustainable production 99

Neem oil (Azadirachta indica)
The evergreen neem tree (Azadirachta indica A. Juss.) is native to India and Burma
and belongs to the mahogany family. It can grow everywhere from semiarid and
semihumid conditions up to 1500m above sea level and its life is >200years. Within
3–5years, neem trees start bearing harvestable seeds and full production may be
reached in 10years. Each year, about 30–50kg of fruit may be produced. Oil yield from
neem seeds is 40–60wt% [39]. The color of Neem oil is light to dark brown and the
taste is bitter. The main constituent of the neem seed oil is Azadirachtin and it varies
from 300 to 2500rpm, depending on the quality of neem seeds and the extraction tech-
nology. The fatty acids present in neem oil are myristic acid (0.2–2.6wt%), palmitic
acid (13.6–16.2wt%), stearic acid (14.4–24wt%), oleic acid (49–62wt%), linoleic
acid (2.3–15.8wt%), and arachidic acid (0.8–3.4wt%) [12]. As per the work carried
out by Awolu and Layokun [40], around 85.13% conversion of crude neem oil to neem
oil methyl esters has been obtained via two-step transesterification method for a
methanol to oil molar ratio of 3:1 at a reaction temperature of 50°C in a reaction time
of 60min using 0.70% (wt of oil) NaOH as a basic catalyst and 1wt% H 2 SO 4 as acid
catalyst [40]. The properties exhibited by neem oil biodiesel includes a kinematic
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viscosity of 3.2–10.9mm /s, a calorific value of 39.6–40.2MJ/kg, a cloud point of 9°C,
and a pour point of 2°C [39].
Mahua oil (Mahua longifolia)
Mahua (Madhuca longifolia) is a tropical tree that is grown in the northern and central
plains and forests of India. It belongs to the family Sapotaceae. The Mahua tree grows
to a height of approximately 20m quickly. It possesses evergreen and semievergreen
foliages and it is adapted even to the arid environments [17]. For the Mahua tree, it
takes 8–15years to mature fully and up to 60years, the mature tree can bear fruit
[12]. Mahua oil is a nonedible vegetable oil obtained from the Mahua tree. Mahua
oil makes as a good initiator for the transesterification process because it possesses
a high content of free fatty acids (FFA). Mahua oil can be transesterified using meth-
anol, ethanol, and butanol into methyl esters, ethyl esters, and butyl esters, respec-
tively [41]. Due to increased thermal efficiency, high efficiency, and a low
stoichiometric air to fuel ratio, methanol is used rather than other alcohols for trans-
esterification. The free fatty acid (FFA) content in Mahua oil is 20wt%, Mahua oil is
characterized by a relatively high percentage of saturated fatty acids such as palmitic
acid (20–25wt%) and stearic acid (20–25wt%) and unsaturated fatty acids such as
oleic acid (41–51wt%) and linoleic acid (10–14wt%) [12]. As proposed by
Muthukumaran et al. [41], the biodiesel yield of 88.71% has been obtained at 60°C
with 1.5% (wt of oil) KOH catalyst in a reaction time of 90min. Mahua biodiesel
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exhibits properties such as a kinematic viscosity of 5.9mm /s, an acid value of
0.30mg of KOH/g, a cloud point of 11°C, and a pour point of 3°C [41].

Jojoba oil (Simmondsia chinensis)
Jojoba (Simmondsia chinensis) belongs to the family Simmondsiaceae and is a peren-
nial shrub that is native to the Mojave and Sonoran deserts of Mexico, California, and
Arizona. It has a lifespan of about 100–200years. The lipid content of the Jojoba seed