Page 131 - Advances in Eco-Fuels for a Sustainable Environment

Prospective ecofuel feedstocks for sustainable production 103

Radish oil (Raphanus sativus)
Radish (Raphanus sativus) belonging to the Brassicaceae family and is a perennial
plant whose oil has been exploited historically in Asia. The radish plant can grow rap-
idly, has tolerance to low temperatures, and possesses excellent ability to recycle soil
micronutrients [53]. The oil content in the Raphanus sativus seed is 40–54wt% and
the oil primarily consists of oleic acid (34.5wt%), linoleic acid (17.8wt%), erucic acid
(16.4wt%), linolenic acid (12.5wt%), and arachidic acid (10.0wt%) [17]. Domingos
et al. [53] found that around 99% conversion of radish oil to biodiesel has been
obtained at 38°C reaction temperature for ethanol to oil molar ratio of 11.7:1 in a reac-
tion time of 60min and using 0.6% (wt of oil) NaOH as a catalyst. Some of the prop-
erties displayed by ethyl esters of radish oil include a kinematic viscosity of
2
4.65–5.01mm /s, an acid value of 0.2mgKOH/g, and a flash point of 182–184°C [53].
Cardoon oil (Cynara cardunculus)
Cardoon (Cynara cardunculus) is a Mediterranean herbaceous perennial thistle
belonging to the Asteraceae family. It has a characteristic rosette of large spiny leaves,
a branched flowering system, and is cultivated for its branched leaf petioles. In many
parts of the Mediterranean, the branched leaf petioles are regarded as a great delicacy.
The free fatty acid (FFA) in cardoon seed oil is 25wt%. The fatty acid profile of car-
doon oil shows the presence of linoleic acid (56wt%) in high quantity while the
other fatty acids such as oleic acid (25.0wt%), palmitic acid (14.0wt%), and stearic
acid (3.0wt%) are present in significant quantities [17]. According to work carried out
by Sengo et al. [54], the methyl esters yield of 97% has been obtained from cardoon oil
in a reaction time of 30min at 52°C for a methanol to oil ratio of 6.4:1 and 1.4% (wt of
oil) CH 3 ONa catalyst. Some of the properties exhibited by methyl esters of cardoon oil
2
include a kinematic viscosity of 4.2mm /s, an acid value of 0.23mgKOH/g, a cetane
number of 51.6, and a flash point of 178°C [54].

Safflower oil (Carthamus tinctorius)
Safflower (Carthamus tinctorius) has been cultivated in the Far East, Central and
North Asia, America, North Africa, Europe, and Caucasia mainly for its seed (source
of a edible oil) and colorful petals (valued as a food coloring and flavoring agent) as
well as a source of red and yellow dyes for clothing and food. It belongs to the
Asteraceae family [55]. The principle producers of safflower are India, the United
States, and Mexico while other countries where safflower has been cultivated are
Kazakhstan, Ethiopia, Argentina, China, Uzbekistan, Australia, Russia, Pakistan,
and Spain. Safflower grows from 30 to 150cm tall with globular flower heads
and has many long, sharp spines on its leaves. There are 1–5 flower heads on a
branch and each head contains 15–20 seeds. The oil content in safflower seed is
35–45wt%. The fatty acid profile of safflower oil shows that it has a high quantity
of linoleic acid (76.0wt%), as well as oleic acid (14.2wt%), palmitic acid
(6.9wt%), and stearic acid (2.1wt%) [17]. As per Rashid and Anwar [55], the fatty
acid methyl ester yield of 98% has been obtained from safflower oil in a reaction time
of 120min for a methanol to oil ratio of 6:1 at a reaction temperature of 60°C and in the