Enzyme Catalysed Biodiesel Production from Rubber Seed Oil Containing High Free Fatty Acid

Unrefined rubber seed oil contains high levels of free fatty acids and moisture which make the conventional chemical catalysed transesterification unsuitable. The method of enzyme catalysed transesterification is well suited for biodiesel production from rubber seed oil as the enzymes are insensitive to the free fatty acids. In the present work, rubber seed oil was extracted from preserved rubber seed cake by mechanical means. The extraction process was designed and optimised through 2⁴ full factorial design. Extracted oil was subjected to enzymatic transesterification using four different lipases to identify the best one for the purpose. Transesterification process was optimised by considering three influencing variables for biodiesel production viz. methanol/oil molar ratio, catalyst concentration (% w/v) and solvent content (% v/v). A 2³ full factorial design was applied to design the experiments and optimise the biodiesel production. The interactive effects of the independent variables on biodiesel yield were analysed and regression models were developed for each set of enzyme reactions. Among the four lipases, Thermomysis Lanugonosus Lipase was found to be the most suitable for the transesterification of rubber seed oil with a biodiesel conversion of 92.83% at a molar ratio of 4 and 5%(w/v) enzyme concentration in solvent free reaction medium.