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 °C. The equilibrium constant increased 1.4 times when the temperature changed from 25 to 50 °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+/Crt/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.

► A chelating resin, Diaion CR 11, was used to remove copper and trivalent chromium.
► The resin exhibited a better selectivity for copper over chromium.
► Multicomponent breakthrough curves were well described by a dynamic model.
► Regeneration of the resin was achieved by using HCl and NaOH/H2O2.