Biodiesel Production from Jatropha curcas Oil

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Biodiesel is a low-emission diesel substitute fuel and the name is widely used for alkyl esters of fatty acids made from vegetable oils or animal fats. Some Asian and African countries are net importers of vegetable oils for human consumption and it is very difficult for these countries to use edible oils for production of biodiesel. India, hence is projecting non edible oils like J. curcas (Jatropha) and Pongamia glabra (karanja) as the main feedstock for the preparation of biodiesel. J. curcas oil is one of the best future renewable tree-borne non edible oil sources for biodiesel production based on its fatty acid composition and low content of unsaponifiable matter. The major drawback of this oil is higher content of free fatty acid and hence lot of care has to be taken during harvesting and handling of Jatropha seeds. Conventional methods of expelling and solvent extraction are being used for extraction of Jatropha oil from its seeds. The most common way to produce biodiesel is through transesterification, especially alkali-catalyzed transesterification. Pre-treatment methods like degumming and esterification are required before transesterification of Jatropha oil, if stringent international specifications of biodiesel are to be met. If Jatropha oil contains less than 1–2 % FFAs, alkali-catalyzed transesterification is the most suitable process for the preparation of biodiesel. In case free fatty acid content is more than 1–2 %, a two step process consisting of esterification followed by transesterification is an appropriate choice for biodiesel production. Homogeneous catalysts like alkali or acids cause various problems such as corrosion, catalyst separation, acid waste, environmental pollution, etc. and hence active research has been initiated by several research groups to replace homogenous catalysts with heterogeneous catalysts (either chemical or enzymatic) or non-catalytic processes for a greener process for the preparation of Jatropha biodiesel. The physico-chemical properties of Jatropha biodiesel almost match with the biodiesel of other feedstocks and conform to all the international specifications. Iodine value and pour points of Jatropha biodiesel are very attractive to exploit this in the colder regions. The cetane number of Jatropha oil-based biodiesel is very high compared to other oilseed sources. Effective utilization of by-products like deoiled-cake, glycerol, phytochemicals and fine chemicals would certainly help the economics of Jatropha biodiesel.