Dependence of pore diffusivity of protein on adsorption density in anion-exchange adsorbent

The ion-exchange adsorption kinetics of bovine serum albumin and gamma-globulin into a porous anion exchanger, DEAE Spherodex M, has been studied by batch adsorption experiments. The parallel diffusion model was employed to predict the pore and surface diffusivities in the model. The effect of the initial protein concentration and adsorption density on the pore diffusivity was investigated by assuming that the surface diffusivity was unchanged with these factors. It was found that the pore diffusivity decreased exponentially with increasing protein adsorption density in a wide range of average adsorption densities. Moreover, the pore diffusivity decreased with increasing the initial protein concentration because of the increase of the adsorption density or the steric hindrance effect for the proteins. The results reported in this paper provided an insight into the dependence of the pore diffusivity of macromolecules in porous adsorbents on adsorption density. (C) 2002 Elsevier Science B.V. All rights reserved.