Modeling of Sorption Dynamics in Transition Metal Ion–Weak-Base Ion Exchanger Systems in Terms of Surface Complexation Theory

Abstract

A model is constructed for sorption dynamics in multicomponent ion-exchange systems with a weak-base ion exchanger. The model is based on computer-solved nonlinear material balances and internal-diffusion kinetic equations. The multicomponent equilibria involving a weak-base ion exchanger are described in terms of surface complexation theory. According to this theory, the fixed amino groups of the ion exchanger (Lewis bases) and sorbate anions form complexes with metal cations (Lewis acids). These complexes are located in different Stern layers at different distances from the surface. Sorption dynamics models are considered for the frontal ion-exchange chromatographic separation of the H+/A/B/X (A, B; = Cu2+, Zn2+, Ni2+, Cd2+; X = Cl−, SO42−) systems on the amino-containing weak-base ion exchangers Purolite A-109 and Fuji PEI-CS-07. Frontal ion-exchange chromatograms are compared for a number of multicomponent systems.