Immobilization of Lipase on KH560 Modified Silica by Sol-Gel Process

An epoxy-functionalized silica support was prepared through 3-glycidoxypropyltrimethoxylsilane(KH560) modified silica sol in the presence of triblock copolymer F127(F-560-S). Surface chemistry, micromorphology and pore structure of the supports were characterized by TG, FTIR, SEM and N sub(2) adsorption-desorption, which showed that the BET surface area and pore volume of epoxy-activated supports increased with the addition of F127. The Candida Antarctica Lipase B(CALB) was immobilized on the resulting carrier by covalent link. The amounts of lipases immobilized were 10 mg/g support and 375 mg/g support on the unmodified silica(U-S) and modified silica(F-560-S), respectively. The immobilized lipases were examined as biocatalysts for transesterification of 1-phenethanol and vinyl acetate in nonaqueous medium. The effects of solvents and temperature on immobilized lipases were systematically investigated. The catalytic activity of the CALB immobilized on F-560-S was improved in various solvents, especially in polar solvents. The immobilized CALBs maintained high activity, while the control experiment using free lipase gave very low ester production in the temperature range of 0-60 [degrees]C. Furthermore, thermal stability of CALB immobilized on F-560-S was improved as compared to the CALB on U-S was observed. The CALB immobilized on F-560-S exhibited high operational stability in organic media which still retained 88.3% of its original activity for 12 h consecutive 7 runs.