Cadmium Adsorption by Activated Carbon Granules Coated with Iron Nanoparticles from Aqueous Solution: Kinetics, Isotherms and Adsorption Mechanism Studies

Background and Cadmium (Cd) is a toxic heavy metal that pollutes the environment via industrial, domestic and agricultural effluents. Its accumulation in aquatic ecosystem could have adverse effects on human health so, its removal from aquatic environment is of great importance. The aim of this study was to evaluate the performance of activated carbon coated iron nanoparticles for the removal of cadmium from aqueous solution. Moreover, kinetic and isotherm models were used to fit experimental data. This fundamental and applied study was performed in laboratory. Adsorbent characterization was determined using X-ray dilatometer (XRD), scanning electron microscope (SEM), and FTIR. Factors affecting the adsorption process such as concentrations of cadmium, pH, time and adsorbent dose in removal of cadmium from aqueous solution were selected and evaluated. The experimental data were evaluated by various isotherm and kinetic models. Data analysis was performed using SPSS V.16. Results of XRD and SEM showed that nanoparticles diameter were 20 nm that was well coated on to activated carbon. With increase in pH, time, concentration, and decreasing of Cd concentration, the rate of cadmium adsorption increased. The highest adsorption rate(approximately 90%) was obtained at pH 9.The results of cadmium adsorption were found to fit well with Freundlich isotherm model (R2> 0.94). Adsorption followed second-order kinetics. FTIR analysis revealed that O-H, C-O-H and amine groups played an important role in sorption of cadmium. According to the results, coated nanoparticles could be used to increase the adsorption efficiency of cadmium and as an effective method in removing of cadmium.