Immobilized Pseudornonas cepacia lipase for biodiesel fuel production from soybean oil,

Enzymatic transesterification of soybean oil with methanol and ethanol was studied. 0f the nine lipases that were tested in the initial screening. lipase PS from Pseudornonas cepacia resulted in the highest yield of alkyl esters. Lipase from Pseudornonas cepacia was further investigated in immobilized from with in chemically inert, hydrophobic sol-gel support. The gel-entrapped lipase was prepared by polycondenzation of hydrolyzed tetramethoxysilane and iso-butyltrirnethoxysilene Using the immobilized lipase PS, the effects of water and :alcohol concentration. enzyme loading, enzyme thermal stability, and temperature in the transesterification reaction were investigated. The optimal conditions for processing log of soybean oil were: 35'C. 1:7.5 oil methanol molar ratio, 0.5g water and 475mg lipase with the reactions with methanol, and 35"C, 1:15.2 oil ethanol molar ratio 0.3s water, 4751ng lipase for the reactions with ethanol. Subject to the optimal conditions, methyl and ethyl esters formation of 67 and 65mol'Z8 in I h of reaction were obtained for the immobilized enz yme reactions. Upon the reaction with the immobilized lipase. the triglycerides reached negligible levels after the first 30min of the reaction and the immobilized lipase was consistently more active than the free enzyme. The immobilized lipase also proved to be table and lost little activity when was subjected to repeated uses.