Al(iii)-based MOF for the selective adsorption of phosphate and arsenate from aqueous solutions

Abstract

The occurrence of harmful ions in water can damage ecosystems and human health. For this, we reported an Al(III)-based MOF (DUT-5), which was synthesized via the solvothermal method and applied to remove phosphate and arsenate from aqueous solutions. DUT-5 displayed high adsorption capacity and stability in the pH range from 4 to 9, besides a high selectivity for phosphate removal and outstanding reusability. The maximum adsorption capacities for phosphate and arsenate were 233.26 and 131.32 mg g⁻¹, respectively. The modeling of the experimental data indicated that chemical forces were involved in the adsorption process since this followed the PSO and Freundlinch models. In addition, the mechanism was elucidated by FTIR and XPS analysis, confirming the possible interactions of the arsenate and phosphate with DUT-5 during the adsorption process. Hydrogen bonding and electrostatic interactions were exhibited for arsenate and hydrogen bonding for phosphate removal. Furthermore, this study confirms that DUT-5 is a suitable adsorbent, significantly contributing to water treatment.