AN IMPROVED MODEL WITH TIME-DEPENDENT ADSORPTION FOR SIMULATING PROTEIN ULTRAFILTRATION

In a recent paper, Gekas et al. (Chem. Engng Sci. 48, 2753-2765) prese nted a theoretical approach to study the adsorption interplay in prote in ultrafiltration. The model is based on transient mass transfer in t he boundary layer and introduces as a novelty the kinetics of adsorpti on on the wall boundary of the membrane, an approach basically differe nt from that of semi-empirical models currently employed. The model us ed two independent kinetic equations: one for the quantity adsorbed at a given time (C-a) and the other for the additional resistance due to adsorption (R-ad) The aim of this paper is to develop and to improve this model, but keeping Gekas' valuable new approach. First, a critica l review of the model is made, correcting the problem statement but ma intaining the two independent kinetic equations formulated. Second, th e model has been modified and improved, using a unique kinetic equatio n for the adsorbed amount of protein, which allows the hydraulic resis tance due to the adsorption to be calculated directly. Results obtaine d with this improved model are compared with those of Gekas et al. The behaviour of fluxes, wall concentration and concentration profiles pr edicted by the improved model are explained more coherently. (C) 1997 Elsevier Science Ltd. All rights reserved.