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

- Mg-Al-Zr triple-metal composite was prepared by a facile co-precipitation method.
- The fluoride adsorption capacity can reach 22.9 mg/g at pH 7.
- The composite can be applied in the wide range of pH.
- The composite exhibited the excellent potential in the real water treatment.

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.

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