Multicomponent Adsorption and Chromatography with Uneven Saturation Capacities

In chromatographic separations involving elutes with large differences in the molecular size, the adsorption saturation capacities of the elutes may differ because of the differences in the degree of size exclusion. With uneven saturation capacities, isotherm crossovers may occur, which often results in selectivity reversal. In this work, a new multicomponent isotherm has been developed for this kind of system. The isotherm is an extension of the common multicomponent Langmuir isotherm and introduces no or a very limited number of new parumeters for its construction. The isotherm crossover conditions have also been derived. Simulations based on a general rate model using the new isotherm have successfully demonstrated the phenomena of peak reversal and crossover of breakthrough curves.