ADSORPTIVE CHARACTERISTICS OF CADMIUM AND LEAD ON THE GOETHITE-COATED SAND SURFACE

Abstract

This study was conducted to develop a heating process for coating crystalline goethite on the sand surface to utilize the adsorbent properties of the coating. Goethite-coated sand was investigated for adsorbing cadmium and lead ions from water by batch and column experiments. Chemical analysis (energy dispersive analysis of X-ray, EDAX) was used for characterizing the cadmium and lead adsorption sites on goethite-coated sand. From the results of the batch experiments, the cadmium and lead ions could be adsorbed effectively on the goethite-coated sand. Maximum adsorption capacity values for cadmium and lead were 319, 704 μg-Cd/g-sand and 702, 1241 μg-Pb/g-sand at pH = 5.0, pH = 6.0, respectively. The interaction between cadmium, lead ions and goethite on sand surface was primarily to cause the chemical bonding. Results from column experiments indicated that the cadmium and lead ions could be removed higher than 95% before 110, 130 and 66, 85 numbers of pore volume of influent were treated at pH = 5.0 and pH = 6.0, respectively.

Keywords:

• Adsorption
• Coating
• Goethite
• Heavy metal

ACKNOWLEDGMENTS

The authors express their gratitude to the National Science Council, Taiwan (Contract No: NSC 88-2211-E-242-003) and Fooyin Institute of Technology (Contract No: FIT-88-009) for their financial supports.