Removal of Cadmium, Zinc, Lead and Copper by Sorption on Leaching Residue from Nickel Production

A leaching resudue from the nickel production (LRNi), was used to study the removal of selected bivalent cations (Cd, Pb, Cu and Zn) from model aqueous solutions. Batch-type experiments have been performed in solutions with initial concentrations of heavy metals in the range of 20-400 mg.L-1 and the adsorbent dosage 2 g.L-1. All adsorption experiments were carried out at ambient temperature (22+1°C) in orbital shaker. The experimental data were modeled with Langmuir and Freundlich isotherms. The relatively high uptake indicated that LRNi can adsorb considerable amounts of cadmium and zinc (maximum uptake capacity for cadmium: 25 mg/g at pH 7.2 and ca. 40 mg/g for zinc at pH 7). A significant uptake was also observed for copper and lead at pH 5.8 and 6 respectively, which was attributed to the precipitation of the respective insoluble hydroxides.