Post-modification of zirconium based metal-organic frameworks for efficient and selective gold adsorption in wastewater

Abstract

Gold, with extremely high economic benefits, has garnered great attention in the field of recovery. However, efficiently and selectively recovering Au(III) from wastewater solutions presents a significant challenge. In this work, we synthesized a novel metal-organic frameworks (MOFs), namely UiO-66-TBTP (organic compound TBTP was synthesized using 5-tert-butyl-2-hydroxybenzaldehyde, thiosemicarbazide and hydroxyl p-bendibenzaldehyde), through post-modification of UiO-66-NH₂. This designed UiO-66-TBTP shows an ultrahigh adsorption capacity of 718.37 mg/g for Au(III) under the conditions of pH = 5 and 318 K. Experiments and calculation results manifest that the adsorption exhibits a spontaneous endothermic behavior, following second-order kinetics and the Langmuir isotherm model, which suggests that a single-layer chemical adsorption occurs on the adsorption surface. Competitive adsorption and repeated experiments show that UiO-66-TBTP has considerable selectivity and reusability. The characterization and calculation results elucidate that the electrostatic and chelation interactions exist between N and S functional groups on UiO-66-TBTP surface and Au(III), and the sulfur containing functional groups can serve as a significant site in the adsorption process. This work offers promising guidance for the synthesis of functional MOFs, specifically designed to serve as efficient and selective adsorbents for Au(III) recovery from wastewater.