Kinetics of copper adsorption on ion exchange complexing resins

In order to predict the efficiency of a SPE procedure, both the thermodynamics and the kinetics of the sorption is important. The thermodynamic aspects of the sorption of metal ions were previously investigated on the basis of the Gibbs-Donnan model for the ion exchange resins1,2. The fraction of metal adsorbed at equilibrium, obtained experimentally, and that calculated from the sorption equilibria are in good agreement. The kinetics of the removal of copper(II) from aqueous solutions by some complexing resins, such as IC Chelate and Amberlite CG 50 is here investigated. These resins are widely used for separation of heavy metal ions from complex matrices. The effects of different variables the initial metal ion concentration, the presence of ligands, the stirring rate and the acidity, were studied by a batch procedure. The adsorption of Cu(II) on the carboxylic macroporous Amberlite CG50 occurs in 80-100 min, while a much longer time is required for the equilibration with IC Chelate, an iminodioacetic resin with a microporous morphology. For this resin, not only the adsorption equilibria but also the the adsorption kinetics is pH dependent. There is only one rate limiting step in the case of Amberlite CG50, but different rate limiting steps for IC Chelate. This is confirmed by the results obtained using the dynamic fixed-bed column methods. The rate constants obtained from static adsorption experiments are in agreement with the kinetical parameter obtained from dynamic experiments in column. Combining the thermodynamic and kinetical information, it is possible to predict the recovery of copper(II) by SPE.