Recovery Strategy Of Lipase In The Aqueous Phase Of Enzymatic Production Of Biodiesel

As a clean and renewable energy, Biodiesel (fatty acid methyl ester, FAME) has been proved to be an important alternative for fossil diesel. Using free lipase to produce biodiesel is a new research area. The development of biodiesel industry is restricted by the high cost of lipase. In order to recycle the enzyme, in this paper, free lipase in the aqueous phase was recovered by foam separation and macroporous resin adsorption.Free lipase in the aqueous phase can be recovered and enriched by foam separation. Orthogonal experiments were first employed to investigate the effects of air flow rate, initial enzyme concentration and pH value on enrichment ratio, recovery of protein and recovery of enzyme activity. The experimental results showed that the recoveries of protein and enzyme activity reached almost 100% with enrichment ratio of 3.67 while air flow rate, initial enzyme concentration and pH value of feed solution were 10 L/(L.h),0.2 g/L and 7.0, respectively. It was found that initial enzyme concentration significantly influenced enrichment ratio; and pH value palled on all of the response variables. The enzyme activity was well kept during foam separation process. The effects of methanol, glycerol and biodiesel on enzyme recovery were further investigated. It was found that:the presence of methanol dramatically increased the foam formation and enzyme recovery rate; glycerol decreased the enrichment ratio; and biodiesel destroyed the stability of foam. The experimental results indicated that biodiesel concentration should be lower than 0.01% to obtain stable foam formation.Free lipase in the aqueous phase also can be recovered by macroporous resin. The best macroporous resin D3520 was chosen in the actual system. Orthogonal experiments were first employed to investigate the effects of temperature, time, initial enzyme concentration and the ratio of resin/enzyme on recovery of protein. The experimental results showed that the recoveries of protein reached about 95% when the ratio of resin/enzyme was 0.05:1 and the time was more than 2 hours. It was found that the ratio of resin/enzyme significantly influenced on the recovery of protein, and the influence of temperature was very small. The effects of methanol, glycerol and biodiesel on enzyme recovery were further investigated. It was found that:methanol had no influence on the recovery of protein; the presence of glycerol would decrease the recovery of protein rate. The experimental results indicated that biodiesel concentration should be lower than or equal 0.01% to recovery protein.We also investigated the catalyze of resin with absorbed enzyme. The experimental results showed that the resin could stable catalyze 20 batches in tert-butyl system. In aqueous system, the resin with absorbed enzyme could also obtain high yeild of biodiesel, but the lipase was desorbed gradually.