Improving the reusability of an immobilized lipase-ionic liquid system for biodiesel production

Commercial applications of enzymatic biodiesel production have been hindered by the enzyme's high cost and poor reusability. Ionic liquids (ILs) have been proposed as alternatives to organic solvents conventionally used in enzymatic biodiesel production. In this work, the reusability of an enzyme-IL system was tested at different methanol-to-oil molar ratios for four consecutive cycles, of 60 and 120 min each. Extracting biodiesel alone by n-hexane resulted in a sharp drop in the overall activity due to the accumulation of the by-product, glycerol. Extracting glycerol by 1-butanol enhanced the stability and allowed the enzyme-IL to be used successfully for four cycles. This study also shows the effect of methanol inhibition on the enzyme stability. The results of this work provide important information for the success of using enzyme-IL systems for biodiesel production, which is essential for the process to be economic.