Meyers J J, Crosser O K, Liapis A I
Department of Chemical Engineering and Biochemical Processing Institute, University of Missouri-Rolla, 65409-1230, USA.
J Chromatogr A. 2001 Jan 26;908(1-2):35-47. doi: 10.1016/s0021-9673(00)00795-0.
A three-dimensional pore network model for diffusion in porous adsorbent particles was employed in a dynamic adsorption model that simulates the adsorption of a solute in porous particles packed in a chromatographic column. The solution of the combined model yielded the dynamic profiles of the pore diffusion coefficient of beta-galactosidase along the radius of porous ion-exchange particles and along the length of the column as the loading of the adsorbate molecules on the surface of the pores occurred, and, the dynamic adsorptive capacity of the chromatographic column as a function of the design and operational parameters of the chromatographic system. The pore size distribution of the porous adsorbent particles and the chemistry of the adsorption sites were unchanged in the simulations. It was found that for a given column length the dynamic profiles of the pore diffusion coefficient were influenced by: (i) the superficial fluid velocity in the column, (ii) the diameter of the adsorbent particles and (iii) the pore connectivity of the porous structure of the adsorbent particles. The effect of the magnitude of the pore connectivity on the dynamic profiles of the pore diffusion coefficient increased as the diameter of the adsorbent particles and the superficial fluid velocity in the column increased. The dynamic adsorptive capacity of the column increased as: (a) the particle diameter and the superficial fluid velocity in the column decreased, and (b) the column length and the pore connectivity increased. In preparative chromatography, it is desirable to obtain high throughputs within acceptable pressure gradients, and this may require the employment of larger diameter adsorbent particles. In such a case, longer column lengths satisfying acceptable pressure gradients with adsorbent particles having higher pore connectivity values could provide high dynamic adsorptive capacities. An alternative chromatographic system could be comprised of a long column packed with large particles which have fractal pores (fractal particles) that have high pore connectivities and which allow high intraparticle diffusional and convective flow mass transfer rates providing high throughputs and high dynamic adsorptive capacities. If large scale monoliths could be made to be reproducible and operationally stable, they could also offer an alternative mode of operation that could provide high throughputs and high dynamic adsorptive capacities.
一种用于多孔吸附剂颗粒中扩散的三维孔网络模型被应用于一个动态吸附模型，该模型模拟溶质在填充于色谱柱中的多孔颗粒中的吸附。联合模型的求解得出了β-半乳糖苷酶的孔扩散系数沿多孔离子交换颗粒半径以及沿柱长的动态分布，这是在孔表面发生吸附质分子负载时的情况，同时还得出了色谱柱的动态吸附容量作为色谱系统设计和操作参数的函数。在模拟中，多孔吸附剂颗粒的孔径分布和吸附位点的化学性质保持不变。结果发现，对于给定的柱长，孔扩散系数的动态分布受以下因素影响：(i) 柱中的表观流体速度，(ii) 吸附剂颗粒的直径，以及(iii) 吸附剂颗粒多孔结构的孔连通性。随着吸附剂颗粒直径和柱中表观流体速度的增加，孔连通性大小对孔扩散系数动态分布的影响增大。柱的动态吸附容量随以下情况增加：(a) 颗粒直径和柱中表观流体速度减小，以及(b) 柱长和孔连通性增加。在制备色谱中，期望在可接受的压力梯度内获得高产量，这可能需要使用较大直径的吸附剂颗粒。在这种情况下，使用具有较高孔连通性值的吸附剂颗粒，满足可接受压力梯度的较长柱长可以提供高动态吸附容量。一种替代的色谱系统可以由填充有具有分形孔（分形颗粒）的大颗粒的长柱组成，这些分形孔具有高孔连通性，并且允许高颗粒内扩散和对流流动传质速率，从而提供高产量和高动态吸附容量。如果能够使大规模整体柱可重现且操作稳定，它们也可以提供一种替代的操作模式，能够提供高产量和高动态吸附容量。
