Candida rugosa lipase immobilized by a specially designed microstructure in the PVA/PTFE composite membrane

Abstract

A composite membrane made of a hydrophobic synthetic material, PTFE, and a biocompatible material, PVA, is proposed to immobilize lipase. The structure of this composite membrane is specially designed and includes a porous PTFE layer and an ultrafiltration PVA layer. In the present study, enzymes were absorbed in pores of PTFE layer and deposited on the interface between the two layers by a filtration process. The ultrafiltration PVA layer rejects enzymes to control the enzyme loading and prevents enzymes from being dissolved into the aqueous phase. The porous PTFE layer with micrometer pores supplies a hydrophobic environment for immobilized lipases which is propitious to the activation of lipase. An immobilized lipase membrane was employed in a biphasic membrane reactor (BMR) for the hydrolysis of olive oil. The volumetric reaction rate of the BMR was used to evaluate the catalytic ability of immobilized lipase membrane. The effect of the structure of the PTFE support layer and the PVA layer, the lipase loading density and the BMR stability was investigated, and The maximum reaction rate per unit of membrane area (9.25 μmol/h cm 2) in experimental conditions was found to be higher than the value reported in some literature. The leakage of immobilized lipases was small and did not have a great effect on the catalytic ability when an immobilized lipase membrane was employed in the BMR.