Efficient extraction of gold from aqueous solution by azo-phenylthiourea functionalized Zr-MOF

The design and synthesis of effective adsorbent for extracting gold from wastewater has significant environmental and economic implications. However, the development of an adsorbent with high efficiency remains challenging. Herein, we report the synthesis of an azo-phenylthiourea functionalized metal-organic framework (MOF, azo-PT-UiO-66) and its application for the adsorption of Au(Ⅲ) from aqueous solution. The performance of azo-PT-UiO-66 was significantly improved as compared with the unmodified MOF, achieving an adsorption capacity up to 650.07 mg/g. Based on the results of kinetic, isothermal and thermodynamic studies, the adsorptive behaviour was a homogeneous and spontaneous chemisorption. Moreover, characterizations revealed that the appearance of metallic gold was caused by the reduction of Au(Ⅲ) via -NH 2 groups. The density functional theory (DFT) calculations confirmed that the chemisorption is owing to the formation of coordinate bonds between azo, S and Au(Ⅲ). This work provides a clean and sustainable method for the recovery of gold from industrial wastewater.