Equilibrium and kinetic studies on removal of Cu2+ and Cr3+ from aqueous solutions using a chelating resin

In this study, a chelating resin, Diaion CR 11. was studied in order to selectively remove Cu2+ and Cr3+ present in synthetic effluents. Single-component equilibrium isotherm was determined in batch experiments for copper, and an exchange equilibrium based model was used to correlate the experimental data of the binary system Cu2+/H+. It was observed that the maximum capacity of the resin increased 2.3 times when the pH varied from 2 to 5 at 25 degrees C. The equilibrium constant increased 1.4 times when the temperature changed from 25 to 50 degrees C at initial pH of 3. For the operating conditions tested, it was found that the resin exhibited a better selectivity for Cu2+ over Cr3+. A mathematical dynamic model was successfully implemented for describing the saturation behavior of the multicomponent system Cu2+/Cr-t/H+ in the column operation. The regeneration of the resin was also experimentally studied by using HCl followed by a mixture of NaOH/H2O2. High efficiencies were observed for copper during the first step, where it was almost fully eluted from the resin with 1 M HCl. The use of those regenerant agents in the presence of iron seems to effectively strip chromium from the resin. (C) 2011 Elsevier B.V. All rights reserved.