(395l) Characteristics and Defluoridation Performance of Synthesized Zr-La Binary Oxide

Chen, J. P., National University of Singapore
Li, G., National University of Singapore
Ma, Y., National University of Singapore


The Zr-La binary oxide synthesized under optimized conditions and its adsorption behavior for fluoride removal was investigated. The best molar ratio of Zr/La was proved to be 1:2, and the best co-precipitation pH was selected to be pH 11.0. By potentiometric titration study, the pH of zero point charge of the sorbent was found to be around 4.2. The kinetic study showed that the uptake of fluoride reached an equilibrium adsorption by 10 h. The kinetic data correlated well with the pseudo-second-order kinetics model and it indicates that the adsorption process might be chemical sorption. For fluoride removal, Langmuir model fitted the isotherm data better and the maximum adsorption capacity can be calculated as 88.06 mg/g. These coexisting anions such as bicarbonate, phosphate and silicate significantly affected the uptake of fluoride by competitive adsorption, while the coexistence of sulphate, arsenate and humic acid had a negligible influence on fluoride adsorption.