Ligand sorption kinetics of aromatic amines on new ligand-exchanger sporopollenin in cobalt ion form

An approach to study of intraparticle ion-exchange kinetics of aromatic amines such as p-chloroaniline, p-toluidine, and p-nitroaniline as ligands on Co2+ loaded-ligand exchanger of sporopollenin (carboxylated epichlorohydrine [CEP]–sporopollenin) is presented and the ligand-exchange reaction in the resin matrix is shown to be rate-determining. Kinetic studies of aromatic amines as ligands on the CEP–sporopollenin have been performed using continuous column runs. The observed rate seems to be related to the rate of ligand sorption with the mobile phase (ion) and pH in the aqueous phase. The rate of attainment of equilibrium sorption and breakthrough curves of aromatic amines is seen to be nearly similar. With the sorption mechanism deduced to be dominantly particle diffusion-controlled, diffusion coefficients determined were found to range from 1.10−8 to 1.0 10−9 cm2s−1. Coupled with the fact that different concentrations of solution were employed, these results may be interpreted as indicating that particle diffusion is the rate-determining step; on the contrary, film diffusion was not a rate-controlling step in the ligand-sorption process under the conditions employed. © 1995 John Wiley & Sons, Inc.