Permeation decomposition of urea through asymmetrically urease-immobilized ethylene-vinyl alcohol copolymer membranes

Abstract

Urease-immobilized ethylene-vinyl alcohol copolymer (EVA)s membrane was prepared by the covalent bonding of urease on EVA membrane activated with cyanuric chloride. The urease-immobilized EVA membrane had optimum pH at about 7.0 similar to native urease. The Michaelis constant (Km) and the maximum velocity (Vm) of the urease-immobilized EVA membrane were smaller than those of native urease. When the EVA membrane, prepared on a polyethylene (PE) plate by the phase inversion method, was used as a support, urease was asymmetrically distributed in the direction of cross section of the urease-immobilized EVA membrane. The permeation decomposition of urea through the asymmetrically urease-immobilized EVA membrane depended on the asymmetric distribution of urease in the membrane. © 1997 John Wiley & Sons, Inc.