Esterification of lauric acid using lipase immobilized in the micropores of a hollow-fiber membrane

Abstract

A porous anion-exchange hollow-fiber membrane was prepared by radiation-induced graft polymerization and chemical modification to immobilize lipase for enzymatic reaction in an organic solvent. The amount of anion-exchange group introduced to the porous hollow-fiber membrane was 2.5 mol/kgfiber. A lipase solution was allowed to permeate through the porous anion-exchange hollow-fiber membrane, and lipase molecules that adsorbed onto the grafted polymer brush were cross-linked with glutaraldehyde. The lipase was immobilized at a density of 0.14 kglipase/kgfiber, which was equivalent to a degree of multilayer binding of 20. Esterification was carried out by passing a solution of lauric acid and benzyl alcohol in anhydrous issoctane through the lipase-immobilized membrane, and lipase activity was determined. A reaction percentage of 50% was achieved at space velocity 68 h−1. The maximum immobilized lipase and native lipase activities were 8.9 and 0.38 mol/(h·kglipase), respectively. Thus, the activity of the immobilized lipase was 23.4 times higher than that of the native lipase.