Efficient gold (Au)(III) recovery from wastewater using a mercapto-1,3,4-thiodiazole modified Zn-MOF

Efficient recovery of precious metals from secondary resources is of great economic and environmental significance in modern society. Herein, an efficient adsorbent ZIF-8-MTD was designed using 1,3,4-thiadiazole (MTD)-modified zinc-based metal-organic framework (MOF) for efficient recovery of gold (Au)(III) from wastewater. It was found that the ZIF-8-MTD adsorbent has excellent adsorption performance for Au(III), with a maximum adsorption capacity of 1604.53 mg·g −1 at room temperature (15 °C), which is superior to the traditional adsorbent. Particularly, the ZIF-8-MTD adsorbent still maintained a high saturation adsorption capacity of 1088.8 mg·g − 1 at a low Au(III) concentration (10 ppm). The fitting results of adsorption isotherm and kinetic adsorption model indicated that the adsorption process was consistent with Langmuir and pseudo-second-order adsorption models, implying that chemisorption was involved in the adsorption process. Moreover, the results of adsorption selectivity , desorption and adsorption experiments confirmed good adsorption selectivity and recyclability. Combining pH effect experiments, infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS) characterizations, we proposed an electrostatic adsorption mechanism in which the coordination interactions between the -SH functional groups in the framework and Au(III) lead them to be adsorbed to the ZIF − 8-MTD surface and partially reduce it to Au(I). More importantly, the outstanding adsorption performance, high selectivity and strong stability make it have great potential for practical application.