COMPARISON OF THE PERFORMANCES OF OVERLOADED ELUTION AND DISPLACEMENT CHROMATOGRAPHY FOR A GIVEN COLUMN

Using the semi-ideal model, chromatograms were calculated for the separation of a binary mixture on a given column by displacement and elution chromatography. The optimum conditions for the maximum production rate with or without a recovery yield constraint were determined using the simplex algorithm. Mixtures of relative retention 1.20 and 1.70 and relative composition 1:3 and 3:1 were considered. The maximum production rates achieved in both modes of chromatography are close. In all instances studied the ratio of the production rates of the two modes was between 0.5 and 2. Without a yield constraint, for the cases studied the recovery yield achieved in overloaded elution is much higher than that achieved in displacement chromatography. However, the concentration of the fraction collected in the displacement mode is one to two orders of magnitude higher than that of the fraction collected in the elution mode. The choice between the modes of operation will depend largely on the comparative economics of displacer recovery and fraction concentrations.