High‐Efficiency Recovery of Au (III) From Acidic Metallurgical Wastewater Using Sulfonic Acid‐Functionalized UIO‐67‐NH ₂ Metal–Organic Frameworks

ABSTRACT A robust metal–organic framework (MOF) material, UIO67‐PS, was synthesized by grafting sulfonic acid groups onto the UIO67‐NH 2 framework. This modification significantly enhances the electronegativity and coordination‐site density on the MOF surface, enabling threefold higher Au (III) adsorption capacity (536.4 mg/g at pH 2.0 temperature 25°C and agitation speed 120 rpm) compared to pristine UIO67‐NH 2 (168.4 mg/g). The material exhibits exceptional acid resistance and recyclability (91% capacity retention after three cycles). Density functional theory (DFT) calculations and X‐ray photoelectron spectroscopy (XPS) analyses reveal that the adsorption mechanism is governed by synergistic electrostatic interactions and chelation, wherein electron‐rich oxygen/nitrogen‐containing functional groups on the adsorbent surface coordinate with metal ions via covalent bonds to form stable five‐membered ring complexes. Kinetic studies confirm rapid adsorption equilibrium (< 240 min), while thermodynamic analysis indicates an endothermic, entropy‐driven process. Notably, UIO67‐PS demonstrates superior selectivity for Au (III) over competing ions (e.g., Zn 2+ and Cu 2+ ) in simulated e‐waste leachates. Achieving removal rates as high as 80% in real metallurgical wastewater highlights its potential for practical application. This work reveals key coordination interactions, including complexation and electrostatic attraction, within a simulated e‐waste leachate system containing competing ions such as copper and nickel. These insights advance the design strategies of MOFs for sustainable Au (III) recovery and provide a scalable platform for industrial wastewater treatment, contributing to environmental protection and the sustainable utilization of critical material resources.