材料期刊网

以F127为模板剂,采用溶胶–凝胶法制备了环氧硅烷改性剂KH560修饰的二氧化硅(F-560-S),通过TG、FTIR、SEM和N2吸附–脱附等方法对样品表面性质和结构进行了表征.结果表明,F-560-S表面富含环氧基,且具有较大孔径和比表面积.以F-560-S为载体通过共价结合法固定南极假丝酵母脂肪酶B(CALB),结果表明环氧基和载体形貌共同影响固定化酶固载量和酶学性质.F-560-S对CALB的固载量达到375 mg/g support,为普通SiO2(U-S)的37.5倍;F-560-S固定的CALB在多种有机溶剂中催化1-苯乙醇与醋酸乙烯酯的反应时,催化转化率普遍高于U-S固定的CALB,热稳定性和操作稳定性均有明显改善,重复使用7次后F-560-S固定的CALB酶活力仍为初始活力的88.3%.

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 N2 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 con-trol experiment using free lipase gave very low ester production in the temperature range of 0–60℃. 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.