How Microscopic Characteristics of the Adsorption Kinetics Impact Macroscale Transport in Chromatographic Beds

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• 作者：Dzmitry Hlushkou ; Fabrice Gritti ; Anton Daneyko ; Georges Guiochon ; Ulrich Tallarek
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：November 7, 2013
• 年：2013
• 卷：117
• 期：44
• 页码：22974-22985
• 全文大小：485K
• 年卷期：v.117,no.44(November 7, 2013)
• ISSN：1932-7455

文摘

Chromatography aims at maximizing the differential migration (separation) of analytes relative to their dispersive transport (peak broadening). This dynamics involves a complex transport scheme with a hierarchy of characteristic time and length scales, from analyte鈥搒urface interactions to effective macroscale transport behavior. Here we report on results obtained with a comprehensive modeling approach that combines three-dimensional pore-scale simulations of fluid flow and mass transport, i.e., advection鈥揹iffusion in the interstitial void space of a random packing of polydisperse hard spheres (representing a chromatographic bed) with the stochastic model of analyte sorption at the solid鈥搇iquid interface of the packing. The retention factor of an analyte is constructed by independent adjustment of the adsorption probability and the mean adsorption time. The approach can realize any microscopic model of the adsorption kinetics based on a distribution of adsorption sojourn times expressed in analytical or numerical form. We study the impact of the retention factor, adsorption probability, and distribution function for the adsorption sojourn times on the chromatographic plate height in dependence of the mobile phase flow velocity. Our results show that the randomness of both the sorption event and the adsorption sojourn time affect peak broadening. For a given retention factor and flow velocity, a reduction of the average adsorption time leads to a decrease in plate height. This work recovers that models of adsorption chromatography cannot describe the separation process adequately without addressing the microscopic details of sorption at the solid鈥搇iquid interface.