Numerical Analysis of the Impact of Geometric Shape Patterns on the Performance of Miniaturized Chromatography Systems

Various chromatography systems are today widely applied for both analysis and preparation of chemical compounds from complex mixtures. Current trends aim at the miniaturization of such systems, for instance on microchips. One approach is to arrange arrays of small pillars in a micro channel. The pillar surfaces are functionalized such as to adsorb specific substances from a bulk fluid which flows through the channel. The performance of such miniaturized chromatography systems is particularly sensitive to the geometric shape pattern of the pillar array. Dead volumes that are often formed at the channel inlet, outlet and boundaries significantly contribute to the unwanted effect of bulk flow dispersion. The same is true for miniaturized chromatography systems using porous particles in a packed bed. We hence have implemented a two dimensional chromatography model for the analysis and optimization of structured micro pillar arrays. Dynamic surface interaction of solved molecules is taken into account by the kinetic Langmuir model. Variations of the pillar array geometry lead to deviations in the outlet concentration profiles. These deviations can not be described by the one dimensional models that are typically used for the simulation of chromatography on larger scales where the sizes of the channel and of the functionalized media differ by several orders of magnitude. We also have implemented a two dimensional model for studying the interplay of transport and sorption processes in packed bed chromatography with porous particles.