Removal of fluoride from aqueous solution by Mg-Al-Zr triple-metal composite

Mg-Al-Zr triple-metal composite was fabricated by a facile co-precipitation method for fluoride removal. The as-prepared composite was characterized by various technologies. The adsorption experiment was carried out to investigate the fluoride removal performance. The results showed that the uncalcined Mg-Al-Zr composite exhibited the best fluoride removal capacity of 22.9 mg/g from the Langmuir isotherm model. The adsorption kinetics followed the pseudo-second-order model, and the adsorption isotherm could be better described by Langmuir and Freundlich isotherm model. In a wide pH range (3-10), the fluoride adsorption capacity of the composite was relatively high. Adsorption thermodynamics result indicated the adsorption process of fluoride onto Mg-Al-Zr composite was the endothermic reaction. The as-prepared composite exhibited the excellent fluoride removal ability in the real ground water and surface water. Based on the characterization, the fluoride removal mechanism onto the Mg-Al-Zr composite was proposed, including the ion-exchange by hydroxyl group and NO3 and the complexation by hydroxyl group. (C) 2017 Elsevier B.V. All rights reserved.