The dependence of sorbed copper and nickel cyanide speciation on ion exchange resin type

The present study investigates the influence of functional group structure and resin matrix on the speciation of copper and nickel cyanides sorbed onto two commercially available ion exchange resins. Batch experiments were performed using synthetic copper and nickel solutions containing 50 and 200 mg/L free cyanide, respectively. Despite the presence of Cu(CN)32- and Cu(CN)43- in solution, it has been found using Raman spectroscopy that the Imac HP555s resin, which has a polystyrene_divinylbenzene matrix, loads predominantly the Cu(CN)32- complex. In contrast, the polyacrylic resin, Amberlite IRA958, sorbed significant amounts of both Cu(CN)32- and Cu(CN)H-. It has been found that the speciation of nickel cyanide sorbed onto each resin was the same. A recently developed mathematical model based on statistical thermodynamic principles has been used as a tool to understand further the equilibrium sorption of copper and nickel cyanide complexes onto each resin studied. A higher sorption energy for nickel compared to copper has been observed for the sorption onto Imac HP555s. In contrast, the sorption energy for copper was found to be higher than for nickel for the polyacrylic resin, Amberlite IRA958. The values of the model parameters obtained were correlated with the chemical features of each complex in solution as well as sorbed onto the resins.