(519e) Investigation of Solvent System for the Production of Biodiesel From Sludge Palm Oil (SPO) By Enzymatic Transesterification

Biodiesel is a non-toxic, renewable and environmental friendly fuel that can replace the fossil fuels which have issues on toxic emissions, unstable escalation of price and high depletion in reserve.  The high cost of common feedstocks of biodiesel can be reduced by using low cost and abundant waste oils such as sludge palm oil (SPO) especially in Malaysia which produces 40 million tons SPO per year.  In this study, SPO with a very high FFA content (51.64 ± 0.59% as palmitic acid) was used to produce biodiesel using locally-produced Candida cylindracea lipase from a low-cost based medium, palm oil mill effluent (POME).  The inhibition of lipase activity is reduced by studying the effects of several factors to the conversion of free fatty acids (FFA) into biodiesel and the total yield of biodiesel (Y_T).

In this study, sludge palm oil (SPO), a low grade and by-product of palm oil mill industry was used to produce biodiesel by direct enzymatic transesterification using locally produced Candida cylindracea lipases from palm oil mill effluent (POME). The solvent system was investigated by comparing the effect of methanol and ethanol. The yield of biodiesel and conversion of free fatty acids (FFAs) into biodiesel for ethanol were higher than the methanol. Ethanol was selected for the based on the findings of ethanol-to-SPO molar ratio, water content, and additional organic solvent. The optimum factors of ethanol solvent system were 4:1 ethanol/SPO molar ratio in the presence of small water content (1:15-1:10 water/SPO volume ratio).  The optimum factors of process conditions were 10 U, 40⁰C, 250 rpm and 24 hours for enzyme loading, reaction temperature, mixing speed and reaction time respectively.  The highest conversion and Y_T of the optimal conditions from OFAT method was 12.0% and 62.3 % (w/w SPO) respectively.