Selective capture of Pb(Ⅱ) from aqueous solution by mercapto functionalized zirconium-based metal organic frameworks

Abstract

UiO-66, a well-known metal-organic framework (MOF) with large surface area, modifiability, and high stability, has substantial potential for further advancements. In this study, UiO-66 is modifies with thiocyanuric acid (TCA) and 2,5-dimercapto-1,3,4-thiadiazole (MTD) to prepare two high-sulfur-content adsorbents (UiO-66-TCA/MTD). Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and N₂ adsorption-desorption analysis show that the modified materials retain their crystal structure. Adsorption experiments demonstrate that UiO-66-TCA achieves a remarkable Pb(II) adsorption capacity of 967.66 mg/g, representing an 840 % enhancement over pristine UiO-66-NH₂. The material exhibits exceptional selectivity, with separation factors reaching 2700.17 for Pb(II)/Mg(II) and 7967.20 for Pb(II)/Ba(II). X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations confirm that the adsorption mechanism primarily involves surface coordination between sulfur elements in the modification layer and Pb(II), with mercapto groups as the key active sites. This study provides a theoretical basis for the design of sulfur-containing MOF materials and their application in lead-containing wastewater treatment.