Enhancing Au(III) adsorption capacity and selectivity via engineering MOF with mercapto-1,3,4-thiadiazole

Abstract

In this paper, Zr-MOF (Zirconium-based Metal Organic Frameworks) was functionalized with mercapto-1,3,4-thiodiazole and applied to selectively recover Au(III) from wastewater. Various measurements were used to characterize the functionalized Zr-MOF, such as Fourier transform infrared (FT-IR), Field emission scanning electron microscope (FESEM), thermogravimetric (TG), Brunner-Emment-Teller (BET) measurement zeta potential and X-ray photoelectron spectroscopy (XPS). The experiments results indicate that the saturated adsorption capacity of gold ions reached at 301.5 mg/g at room temperature with optimal pH 6. The isotherm adsorption and kinetic adsorption model suggested that the process conformed to Langmuir and pseudo-second-order model. In addition, it can selectively adsorb Au(III) from wastewater. Desorption and adsorption experiments indicate that the adsorbent can be recycled at least 3 times. Combined with zeta potential and XPS analysis, it can be found that ion exchange and chelation were the dominant mechanisms. Five binding modes were used to calculate the binding energy during the adsorption process using DFT calculation, indicating that the sulfur-containing functional groups play a major role in the adsorption process.