Oxidation of glucose on immobilized glucose oxidase.

Abstract

Oxidation of glucose on immobilized enzymes was carried out to study the effect of intraparticle mass transfer of oxygen on the global rate of the reaction. The catalyst employed, which consisted of both glucose oxidase and catalase supported on activated carbon, was prepared by the carbodiimide method. The experiments were performed in 0.1M acetate buffer solution (pH=5.5) and at 25°C. The initial rates of reaction were determined from the absorption rates of oxygen gas, under conditions of no external mass transfer resistances. Nonlinear least-squares analysis gave values of the maximum velocity (V), the Michaelis constant (Km), the effective diffusivity of oxygen (D6) and the tortuosity factor of the particles (τ) of V=8.30×10-6 [mol/ (g-cat·s)], Km=9.46×10-5 [mol/cm3], De=7.70×10-6 [cm2/s] and τ=2.0 [-], respectively. The effectiveness factor calculated from these values indicated that the intraparticle mass transfer of oxygen in the liquid significantly influences the global rate of reaction.