Kinetics of Sorption of Cu(II)−Ethylenediaminetetraacetic Acid Chelated Anions on Cross-Linked, Polyaminated Chitosan Beads

Rates of sorption of Cu(II)−ethylenediaminetetraacetic acid (EDTA) chelated anions from aqueous solutions on cross-linked, poly(ethylenimine) (PEI)-modified chitosan beads were measured in a batch stirred vessel. All experiments were carried out in an equimolar solution of Cu(II) and EDTA (0.47−3.15 mol/m3). It was shown that the rates of sorption increased with an increase in the initial concentration of Cu(II), pH, and temperature but decreased with an increase in the molecular weight of PEI introduced in the beads. The widely used homogeneous diffusion model based on Fick's law and the shrinking core model cannot describe the sorption process. On the contrary, the kinetic data were well fit by the Elovich equation. The apparent activation energies evaluated (3.5−8.4 kcal/mol at pH 3) indicated the combined film and particle diffusion mechanism.