“Perfusion chromatography”. The effects of intra-particle convective velocity and microsphere size on column performance

Abstract

A mathematical model describing the dynamic adsorption in columns with spherical bidisperse perfusive or spherical bidisperse purely diffusive adsorbent particles is presented and its solution is obtained numerically. The adsorption of bovine serum albumin on spherical anion-exchange porous particles was studied for different values of the intraparticle Peclet number, Pe intra, and of the microsphere diameter, d m. The results show a departure from spherical symmetry of the isoconcentration profiles of the adsorbate in the porous adsorbent particle as Pe intra increases. This spherical asymmetry increases the adsorbate availability in the pore fluid of the macroporous region and also increases the concentration of the adsorbate in the adsorbed phase in the upstream half of the spherical adsorbent particle. If, for example, the concentration profiles of the adsorbate in the adsorbed phase of the porous adsorbent particles could be determined experimentally and if these profiles show a departure from spherical symmetry, then this result could suggest that the porous adsorbent particles may have exhibited perfusion behavior under the conditions of operation of the column. The dynamic percentage utilization of the adsorptive capacity of the column increases as Pe intra increases and d m decreases. The percentage breakthrough to be selected for column switching is influenced by the magnitude of Pe intra because of its effect on the dynamic percentage utilization of the adsorptive capacity of the column.