Ethyl ester production using immobilized lipase entrapped in loofa reinforced alginate carriers

Abstract

This work investigated the biodiesel production from purified palm oil and palm fatty acids by using free and immobilized lipases as biocatalysts. Two methods of lipase immobilizations were studied: 1) adsorption of lipase onto loofa (CRLA) and 2) entrapment of loofa-lipase in Ca-alginate matrix (CRLAE). CRLAE was prepared by using 10% lipase based on oil weight and 2% w/v Na-alginate. The reaction conditions were at 45oC, 250 rpm and 3 layers of alginate coated on CRLAE. For the biodiesel production, the optimal condition for using ethanol was at 99.9% ethanol, 0.001 M phosphate buffer and 36 h of reaction time, yielded approximately 78.87% and 96.18% ethyl ester by the free lipase and CRLAE, whereas the optimal condition for using methanol were at 99.9% methanol, 0.001 M phosphate buffer and 12 h of reaction time, the biodiesel production by the free lipase and immobilized lipase in CRLAE resulted in methyl ester yields of 96.97% and 97.92%, respectively. The results from the reuse of the immobilized lipases revealed the significant reduction of ethyl ester yield from the 1st run to the 2nd run and from the 1st run to the 5th run for methyl ester yield. On the other hand, when using the mixture of purified palm oil and palm fatty acid in the initial mass ratio of 70:30 as substrate, the result showed that, under semi-continuous feeding of palm fatty acid, the ethyl ester yields obtained by using 95.0% ethanol, 99.9% ethanol and 99.9% methanol were relatively high and the enzymatic activity remained constant during the 5 repeated uses