Synthesis and Characterization of Ce-La Binary Oxide for Efficient Fluoride Removal

Abstract

In this study, a novel Ce-La binary oxide sorbent was synthesized by a co-precipitation method and the adsorption performance of the sorbent for fluoride removal was investigated. The best molar ratio of Ce/La was proved to be 1:2, and the co-precipitation pH was selected as pH 11.0. By potentiometric titration study, the pH_zpc of the sorbent was found to be around pH 7.8. Adsorption kinetics study showed that most fluoride uptake took place at the first 4 h followed by a relative slow process, and the adsorption equilibrium could be obtained within 10 h. The kinetic data correlated well with the pseudo-second-order kinetics model. The optimum pH range for the fluoride adsorption is 3-10. Isotherm study indicated that the Langmuir model can be well used for the description of the fluoride adsorption. These coexisting anions such as bicarbonate, phosphate and silicate significantly affected the uptake of fluoride by competitive adsorption.