Efficient and selective recovery of Au(III) from aqueous solution by functionalized UiO-67 materials: Cooperative effects of diamino-functionalization and charge modulation

The recovery and utilization of precious metals from secondary resources are important owing to their pivotal role in modern technology. In this study, we successfully grafted diamine onto UiO-67, modulated its charge and functionalization, and developed a highly efficient adsorbent for the extraction of Au(III) from waste solutions. The recovery rate of UiO-67-(NH2)(2) for trace gold is >99 % in the wide range of pH 3 to 9. The maximum adsorption capacity of UiO-67-(NH2)(2) at a temperature of 298 K is 482 mg/L. In addition, UiO-67-(NH2)(2) exhibits excellent selectivity to Au(III) in mixed metal ion waste solutions. After five cycles of adsorption-desorption experiments, the adsorption efficiency remains above 95 %. The identification of electrostatic interactions, coordination, and reduction as the primary adsorption mechanisms is supported by X-ray photoelectron spectroscopy (XPS) analysis of UiO-67-(NH2)(2) and density functional theory (DFT) calculations.