Modeling chromatographic columns: Non-equilibrium packed-bed adsorption with non-linear adsorption isotherms

In this work a new mathematical model, based on non-equilibrium conditions, describing the dynamic adsorption of proteins in columns packed with spherical adsorbent particles is used to study the performance of chromatographic systems. Simulations of frontal chromatography, including axial dispersion, for non-equilibrium systems with non-linear adsorption isotherms are made and compared to those of the experimentally determined protein A affinity chromatography breakthrough curves of hIgG, gathered from the literature. The non-equilibrium model developed here combines external mass transfer and intra-particle transport by solid (surface) diffusion, and permits the prediction of (time and bed height dependent) interface and average solid concentrations, along with interface and bulk liquid concentrations. The present non-equilibrium approach significantly improved the model predictions of experimentally observed distended breakthrough fronts over local equilibrium based models, and can be used to evaluate the influence of system parameters on the performance of chromatographic packed-bed adsorption columns.