(118c) Continuous Annular Chromatography: Simulation of Multicomponent Separation Via the General Rate Model for Nonlinear Adsorption Isotherms

Chromatography is a highly selective process of separation which is often employed in the separation of complex mixtures such as sugars, proteins, pharmaceuticals, fine chemicals, flavorings, foods, enantiomers and isomers. Conventional preparative elution chromatography is a batch process. As opposed to conventional batch chromatography continuous chromatographic separation processes, have gained greater interest in the last decades due to its advantages in terms of productivity and eluent consumption. Continuous Annular Chromatography (CAC) is a potential and promising process intensified technology that allows large-scale continuous preparative chromatographic separation and purification of multi-component mixtures. The interest on continuous chromatography has motivated a great deal of theoretical work to achieve a better understanding of CAC to devise useful simulation procedures for design and process development purposes. In the literature CAC models have been proposed and solved [1] where, it is assumed that the equilibration of a solute between the mobile and stationary phase is an infinitely rapid process. Any contributions from hydrodynamic effects or mass transfer phenomena are neglected. However, for the preparative separations of several large molecular compounds such as proteins the diffusion of solute in the stationary phase is slow since mass transfer resistances are abundant. Therefore in order to obtain sufficiently accurate simulation results, use of accurate mathematical models is required. The general rate model (GR) accounts external and intraparticle mass transfer resistances, as well as dispersion [2]. The solution of the GR model based CAC governing equations involves the employment of advanced numerical techniques that requires considerable machine time. For homogeneous diffusion, Özdural et al. [3] proposed a new algorithm for numerical solution of the GR model in chromatographic columns. The advantage of this methodology lays in the fact that it does not require the solution of coupled partial differential equations; instead the stationary phase concentrations were evaluated through unsteady state component mass balance expressions written in discretization schemes. Thus the number of partial differential equations to be solved reduces to one and the computation time significantly lessens. In this study this technique is extended to multicomponent systems and applied to Langmuir type nonlinear isotherms in CAC separation systems. This is the first of its kind where a sophisticated chromatography model, i.e. the GR model, is employed in CAC simulation studies. Use of this new methodology allows us to suggest protocols for system operation parameters and/or scale-up processes, especially for the continuous chromatographic separation of biomolecules where mass transfer resistances are usually high. [1] Thiele A., Falk T., Tobiska, A. Seidel-Morgenstern L. (2001) Prediction of elution profiles in annular chromatography. Computers and Chemical Engineering, 25: 1089?1101. [2] Guiochon G., Lin B. (2003) Modeling for Preparative Chromatography. San Diego: Academic Press. [3] Özdural A.R., Alkan A., Kerkhof P.A.J.M. (2004) Modeling chromatographic columns: Non-equilibrium packed-bed adsorption with non-linear adsorption isotherms. Journal of Chromatography A, 1041: 77-85.