A diffusion-reaction kinetic model for the removal of aqueous 4-chlorophenol with immobilized peroxidase

Abstract

A diffusion-reaction kinetic model is presented for the kinetic analysis of the removal process of phenolic compounds using hydrogen peroxide and immobilized peroxidase. The good results obtained in the fitting of the experimental data to the model confirm its validity, in the experimental range considered, as well as the one of the extended version of the Dunford mechanism proposed in a previous paper.The phenomenon of enzyme deactivation and/or sequestration by the precipitated olygomers/polymers, which has been widely described in the literature, is here modeled as the growth of a polymeric film over the external surface and inside the pores of the catalytic particles that contain the enzyme, thus determining the appearance of diffusional limitations and an increasing loss of activity. The deactivation phenomena, interpreted and modeled in terms of the effectiveness factor, are included in the kinetic model.To confirm the validity of the model, several series of experiments were carried out in a discontinuous tank reactor. Some of these experimental series were used to obtain the values of the kinetic parameters by numerical calculation and using an error minimization algorithm. Since the model reproduces the behavior of the system for the series of experiments not used for the determination of the parameters, it can be affirmed that the model is suitable for the kinetic analysis of the system under study.