Cadmium(II) Removal by Modified Zeolite from Micro-Polluted Water

Abstract

Cadmium(II) in water sources has threatened the availability of safe drinking water and, thus, human health. Therefore, development of a feasible technique for cadmium(II) removal from micro-polluted water is urgently needed. In this study, modified zeolite powder, a new adsorbent, was prepared from natural zeolite powders, chitosan, and sodium hydroxide and was analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy. It was used to remove cadmium(II) from a micro-polluted water source. The effect of adsorption time, pH, initial cadmium(II) concentration, and zeolite powder dosages on the removal of cadmium(II) was investigated. Results show that the cluster structures became porous structures in the modified zeolite powder. Chitosan was supported on the zeolite. The process formed porous structures with a large inner specific surface area. Under the experimental conditions, maximum cadmium(II) adsorption capacities were 0.159 mg·g−1 for the natural zeolite powder and 1.011 mg·g−1 for the modified zeolite powder. Cadmium(II) was more effectively removed by the modified zeolite powder than by natural zeolite powder. Equilibrium adsorption data were analyzed by Langmuir, Freundlich, and Dubinin-Kaganer-Radushkevich isotherm models. A pseudo second-order adsorption kinetics model was used to describe the adsorption processes.