One-Pot Synthesis of Azine-Functionalized Zr-MOFs for Efficient Au(III) Adsorption: Mechanism and Performance

Efficient recovery of Au (III) from aqueous wastewater is of great significance for resource utilization and environmental protection. Herein, azine-functionalized Zr-based MOFs (hereinafter referred to as AZA-Zr-MOFs) were prepared via a facile one-pot solvothermal route using 2,2'-diamino-4,4'-(4-amino-1,2,4-triazole-3,5-diyl) dibenzoyl acid as the organic linker. The abundant triazole and amino groups on the MOF surface provide multiple active sites for multi-nitrogen synergistic coordination, thus enhancing the selective capture of Au (III) in aqueous solution. The obtained AZA-Zr-MOFs exhibit a high maximum uptake capacity of 1176 mg/g for Au(III), along with remarkable selectivity and excellent cycling stability (＞90 % efficiency after 5 cycles) over a wide pH range (2.0~9.0). Combined with experimental analyses (X-ray photoelectron spectroscopy (XPS), zeta potential, Fourier transform infrared spectroscopy (FTIR)) and density functional theory (DFT) calculations, the liquid-phase adsorption mechanism of Au (III) is clarified as a synergistic effect of amino-assisted reduction (Au (III)→Au (0)), nitrogen-centered coordination on the MOF surface, and electrostatic interfacial interaction via protonated amino groups. This work provides a feasible preparation method for MOF-based adsorbents and reveals the key role of surface functional groups in the interfacial adsorption of Au (III), which has potential application value for Au (III) recovery from actual aqueous wastewater.