Jatropha curcas is a species of flowering plant in the spurge family, Euphorbiaceae, which is native to the American tropics, most likely Mexico and Central America. It is cultivated in tropical and subtropical regions around the world, becoming naturalized in some areas. Jatropha curcas is a non-edible oil crop predominantly used to produce bio-diesel. The seeds contain 27-40% oil (average: 34.4%) that can be processed to produce a high-quality biodiesel fuel, usable in a standard diesel engine. In this study, Jatropha seeds for extraction of oil were obtained from Meru and Tharaka Nithi, Kibwezi, Oyugis and Funyula research plots. Straight Jatropha oil was extracted and its physical and chemical properties were analysed according to the American Standards Testing Materials (ASTM D4052) protocols. The oil was then trans-esterified to produce their methyl ester as Jatropha biodiesel. The physical and chemical properties of biodiesel were also analysed. It was found that the density of Jatropha seed oil was between 1.0802 - 1.0864 g/cm3 at 20Â°C whereas that of biodiesel was in the range of 0.8786â€“0.8808 g/cm3. Acid value of Jatropha oil was between 1.35 - 4.19 mgKOH/g and that of the biodiesel was between 0.31 - 0.86 mgKOH/g, and kinematic viscosity of biodiesel was between 4.3 to 4.8mm2/s at 40Â°C. From the results obtained, it is concluded that straight Jatropha oil after trans-esterification process to produce biodiesel, was found to be suitable for direct usage as fossil fuel substitute. The parameters of the biodiesel produced were within the limits of those set out in the ASTM standards for biodiesel and can therefore be a suitable substitute for fossil fuel based diesel. Using Jatropha as a source of biodiesel in Kenya would save on foreign exchange used to import fossifuels, create jobs for youth and contribute to reduction of the effects of greenhouse gases emissions.
Keywords: Jatropha curcas, biodiesel, physico-chemical characterization