Adsorption of Zn2+, Cd2+ and Cu2+ on zeolites coated by manganese and iron oxides

Abstract

Adsorption of copper, cadmium and zinc on manganese and iron oxide coated zeolite from aqueous solution was investigated in a batch mode. Experiments were conducted to investigate the effects of the initial concentration of metals, initial pH, contact time and temperature on the adsorption of ions. According to the results, adsorption of ions on manganese and iron oxide coated zeolite increased with the enhancement of initial Cu 2+ , Zn 2+ and Cd 2+ concentrations and contact time and also with increase of temperature. The results showed that at the beginning, the adsorption rate of Cu 2+ and Cd 2+ was more than 90 %. This rate continued to be slower for Zn 2+ in both zeolites. Furthermore, the amount of Cu 2+ , Zn 2+, and Cd 2+ adsorption on the manganese oxide coated zeolite (qe) was equal to 14 mg/g, 9 mg/g and 16 mg/g and on the iron oxide coated zeolite it was 11 mg/g, 7 mg/g and 13mg/g, respectively. It was shown that at the concentrations below 100 mg/dm 3 adsorption was rapid and almost all heavy metals were adsorbed. As a result, the significant factor affecting qe is the proportion of weight to liquid and pH in the solutions. Finally, the results showed that the adsorption of Zn 2+ , Cu 2+ and Cd 2+ onto the manganese oxide coated zeolite followed both the Langmuir and Freundlich isotherm models.