Influence of impurities on biodiesel production from Jatropha curcas L. by supercritical methyl acetate process

Generally, water and free fatty acid (FFA) content in oils could cause a serious problem during conventional transesterification such as saponification. Thus, without any pre-treatment, vegetable oil, especially with high FFA content, will be affected. In this study, a non-catalytic supercritical methyl acetate (SCMA) process was utilized to produce biodiesel from Jatropha curcas L. oil. The effects of water and FFA content on the yield of biodiesel were investigated. The results obtained for the effects of water on the yield of biodiesel were compared with the supercritical methanol (SCM) process and conventional catalytic reaction. Results revealed that the catalytic reaction suffers from low yield with the presence of high water content in oil. Meanwhile, the yield of both the SCM and SCMA reactions were found to increase slightly with the increment of water content in the mixture. On the other hand, the results for the effect of FFA on the yield of biodiesel were compared with the SCM reaction. It was found that the presence of FFA has a negligible effect in both the SCMA and SCM reactions. These findings demonstrate that pre-treatment procedures are not necessary in the SCMA process for Jatropha oil which normally contains a high FFA content.