Study on the adsorption of cadmium(II) from aqueous solution by D152 resin

The feasibility of using D152 resin as an adsorbent for cadmium(II) was examined. The adsorption capacity of D152 resin for cadmium(II) ions was studied as a function of solution pH, temperature and contact time. The optimal pH for the adsorption of cadmium(II) ions was found to be 5.95 in the HAc-NaAc system. The maximum uptake capacity of cadmium(II) was estimated to 378 mg/g D152 resin at 298 K, at an initial pH value of 5.95. The results obtained from equilibrium adsorption studies were conformed to the Langmuir and Freundlich and the correlation coefficients have been evaluated. The apparent adsorption rate constant was k298K = 4.01 × 10−5 s−1, and the apparent activation energy was 2.78 kJ/mol. Thermodynamic parameters, ΔS was 108 J/(mol K), heat of adsorption (ΔH) value of 12.8 kJ/mol indicated the endothermic nature of the adsorption process, and a decrease of Gibbs free energy (ΔG) with increasing temperature also indicated the spontaneous nature of the process, respectively. The elution tests were carried out using various mixed reagents. The maximum elution percent of cadmium(II) ions were obtained when the reagent 0.5 mol/L HCl was used.