Multi-component perfusion chromatography in fixed bed and periodic counter current column operation

A mathematical model of multi-component dynamic adsorption in columns with spherical perfusive and spherical purely diffusive adsorbent particles with a bidisperse porous structure is constructed, solved, and used to study the performance of a binary adsorption system in a single-column fixed-bed process and in a two-column periodic counter-current process in which the adsorbent, is equally distributed over two beds. The total length of the two-column periodic counter-current system is equal to the length of the single-column fixed-bed system. The performance of fixed-bed and periodic counter-current systems with both perfusive and purely diffusive adsorbent particles is examined for different values of the macropore void fraction, epsilon(p), the particle diameter, d(p), the inlet concentration of the least preferentially adsorbed component 2, C-d2,C-in, and the superficial velocity, V-f. For the binary adsorption system studied in this work, the results show that the adsorption column must be operated in the periodic counter-current mode at low values of the superficial velocity, V-f, in order to achieve high relative separation efficiency. Under these conditions, the performance of the adsorption column does not depend upon epsilon(p), or d(p). The relative separation efficiency decreases somewhat and is no longer independent of epsilon(p) and d(p) when V-f is increased moderately. At high values of V-f, the relative separation efficiency is unsatisfactory for all cases. The performance of systems with perfusive adsorbent particles is slightly better than the performance of systems with purely diffusive adsorbent particles for some values of V-f.