Selective separation of copper and cadmium in aqueous solution using bis‐picolylamine functionalized resin

Abstract Coexistence of copper and cadmium in natural ores and waste materials including wastewater requires the separation of copper and cadmium from aqueous systems to produce pure respective metals and utilize metal resources comprehensively. Selective separation of Cu(II) and Cd(II) ions from synthetic solution using resin adsorption was explored by testing 30 resins bearing various functional groups. It was found that a chelating resin containing bis‐picolylamine functional groups, that is, Lewatit® MDS TP 220, had adsorption preference for copper ions over cadmium ions in the aqueous system. The effects of resin dosage, pH, contact time, adsorption temperature, and metal concentrations were investigated systematically using a batch process, and the optimum adsorption conditions were obtained at pH 2.5, resin dosage 0.03 g/mL, and contact time of 150 min. The adsorption results are very consistent with the Langmuir model from the isotherm modelling; the maximum adsorption capacities of the resin were 111 mg/g for Cu(II) and 40 mg/g for Cd(II), respectively. The values of the calculated thermodynamic parameters indicate that the nature of the metal adsorption process is spontaneous and exothermic; and the metal ion adsorption kinetics fit well for the pseudo‐second‐order model. At low metal concentration levels, the MDS TP 220 resin could be used as an efficient absorbent for the removal as well as selective recovery of copper ions from wastewater.