Evaluation of removal efficiency of fluoride from aqueous solution using nanosized fluorapatite

In this study, the potential of nanosized fluorapatite (nFAP) for fluoride removal from aqueous solution was evaluated. Several parameters including adsorbent dosage, contact time, initial fluoride concentration and pH were investigated for their effects on the removal of fluoride. A detailed analysis of the regression coefficients showed that Langmuir and Freundlich models adequately described the adsorption data, but the data were better fitted by the Langmuir isotherm. While the pseudo-second-order model was the best choice to describe the fluoride adsorption behavior, and thermodynamic studies revealed that the adsorption of flouride by nFAP was spontaneous and endothermic in nature. nFAP exhibited a great defluoridation capacity up to 7.45 mg/g, which was similar to that of nanosized hydroxyapatite (7.75 mg/g). In consideration of the lower cost and easier regeneration property of nFAP, it would provide an alternative for the adsorption and removal of fluoride from aqueous solution.