Nonlinear model of liquid chromatography considering finite rates of adsorption-desorption kinetics and core-shell adsorbents

Abstract

A nonlinear general rate model is numerically approximated to simulate fixed-bed chromatographic columns packed with core-shell particles. The model incorporates explicitly the effect of finite rates of adsorption and desorption at the adsorption sites, typically assumed to be very fast compared to the rates of the various transport processes. Using core-shell particles as a stationary phase can have advantages over applying a fully-porous stationary phase, such as higher efficiencies and better resolution of the sample components. A high resolution finite volume scheme is extended and applied to approximate the model equations. Ranges of the kinetic parameters in which limited rates of the intrinsic adsorption and desorption steps needs to be taken into account are estimated. A few case studies of predicting the elution of single-component and two-component mixtures are considered to evaluate the effects of adsorption and desorption rate constants, core-radius fraction, axial-dispersion coefficient, film mass transfer, and intraparticle diffusion on the elution profiles. Furthermore, it is demonstrated that optimum values of the inert core radius can be obtained by evaluating a typical criterion for process performance.