Crop description. J. curcas—commonly known as pourghere, ratanjyot, Barbados nut, physic nut, parvaranda, taua taua, tartago, saboo dam, jarak butte, or awla—belongs to the family Euphorbiaceae and grows in hot, dry, tropical climates (see Fig. 4.6). It originated from South America and is now found worldwide in tropical countries. It grows wild especially in West Africa, and is grown commercially in the Cape Verde Islands and Malagasy Republic. The tree reaches a height of 8 m and is a tough, drought-resistant plant that bears oil-rich seeds prolifically under optimum growing conditions [75]. The seeds contain about 55% oil [76]. The oil contains a toxic substance, curcasin, which has a strong purging effect. Major fatty acid composition consists of myristic acid (0-0.5%), palmitic acid (12-17%), stearic acid (5-6%), oleic acid (37-63%), and linoleic acid (19-40%) [77].

Main uses. It has been cultivated as a drought-resistant plant in mar­ginal areas to prevent soil erosion. The oil has been commercially used

Figure 4.6 Jatropha curcas. (Photo courtesy of Piet Van Wyk and EcoPort [www. ecoport. org].)

for lighting purposes, as lacquer, in soap manufacture, and as a textile lubricant. It is also used for medicinal purposes for its strong purging effect. The leaves are used in the treatment of malaria. Products useful as plasticizer, hide softeners, and hydraulic fluid have been obtained after halogenation [75]. The wood is used for fuel. The cake, after oil extraction, cannot be used for animal feed due to its toxicity, but is a good organic fertilizer. The wood is very flexible and is used for basket making. A water extract of the whole plant has molluscicide effects against various types of snail, as well as insecticidal properties [77].

Recently, there has been considerable interest in the use of the oil in small diesel engines. This oil has great potential for biodiesel production [78-80]. Foidl et al. transesterified J. curcas oil, using a solution of KOH (0.53 mol) in methanol (10.34 mol) and stirring at 30oC for 30 min [81]. The ester fuel has high quality and meets the existing standards for vegetable-oil-derived fuels. Some researchers have proposed the use of immobilized enzymes such as Chromobacterium viscosum, Candida rugosa, and Porcine pancreas as a catalyst [82, 83]. Modi et al. have proposed the use of propan-2-ol as an acyl acceptor for immobilized Candida antarctica lipase B. Best results have been obtained by means of 10% Novozym-435 based on oil weight, with a alcohol-oil molar ratio of 4:1 at 50oC for 8 h [84]. Zhu et al. have proposed the use of a heterogeneous solid superbase cat­alyst (catalyst dosage of 1.5%) and calcium oxide, at 70oC for 2.5 h, with a methanol-oil molar ratio of 9:1 to produce biodiesel [85]. The lubrication properties of this biodiesel have also been taken into consideration [51].