Abstract

This study investigated ethanolysis of both crude and pre-treated Jatropha oil using immobilized lipase from Pseudomonas cepacia. The methods employed were stepwise addition of ethanol and n-hexane as solvent. The ethanol was added three times in a stepwise way so as to prevent enzyme inhibition. The effects of reaction temperature and oil to ethanol ratio were studied. Maximum yields of fatty acid ethyl ester (FAEE) of 66.7 wt%, 72.1 wt% and 58.8 wt% were obtained at oil to ethanol ratio of 1:4 for crude Jatropha curcas oil at reaction temperatures of 30, 40, and 50 ^oC respectively. Each run of the experiment took an overall reaction period of 48 h. These results showed the best optimized reaction temperature to be 40 ^oC. A maximum FAEE yield of 96.1 wt% was obtained when pre-treated Jatropha curcas oil was transesterified at the best optimized conditions. The loss noticed after 13 cycles in the activity of the enzyme was quite negligible. This proved it to be a stable one. The physical properties of the biodiesel obtained from the pre-treated Jatropha oil met the ASTM standard of D-6751.

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