Simulating Complex Displacement Chromatography Systems

Abstract

A mathematical description is developed for complex displacement chromatography (CDC) systems. It consists of mathematical models of the stationary state of each forming zone. It is noted that the theoretical analysis of elution systems is based on the principle of successively considering equilibria and calculating the concentrations of all varieties of ions in both phases. Numerical experiments are performed on eluting rare earth elements (REEs) on sulpho cation exchangers using eluents based on diethylenetriaminepentaacetic acid (DTPA). It is shown that increasing the pH and concentration of the eluent and the buffering species introduced into the eluent sharpen the displacement fronts. It is concluded that in the zone of a sorbed complexone, its concentration is many times greater than in the initial eluent. It is shown that raising the concentration of the displacing agent raises the pH and concentration of the eluted component, due to an increase in the amount of introduced alkali and the introduction of additional complexing or buffering species. A maximum is found on the curve of the REE content in the solid phase, which corresponds to the HETP minimum.