Thioether-functionalized covalent organic framework for mercury removal

Post-synthetic modification of COFs via pendant groups or secondary functional groups of the skeleton structure is an important strategy to introduce new properties or enhance existing properties of COFs. Herein, we take advantage of the inherent advantages of COFs and introduce thioether functional groups into a reasonably designed novel COF (TAPA-TFPD) through a post-synthetic modification strategy to create a promising thioether functionalized adsorbent for mercury removal. The thioether functionalized COF material, TAPA-TFPD-S-S, exhibited high mercury removal efficiency from aqueous solution, and the adsorption capacity of Hg2+ was up to 593 mg/g. This efficient mercury removal performance can be attributed its well-defined pore channel sufficient to facilitate Hg2+ diffusion together with high concentration of sulfide chelating sites distributed uniformly throughout the pore wall. The strong interaction between Hg2+ and the thioether groups of TAPA-TFPD-S-S was confirmed by XPS. In addition, TAPA-TFPD-S-S also has the ability to capture Hg0 from the air. The efficient capture of mercury species from aqueous solution and air and the excellent reusability make the prepared thioether-functionalized COFs have great development potential in practical applications. Our work not only demonstrates the utilization of thioether-functionalized COFs in the removal of heavy metal contaminants, but also highlights the exceptional potential of post-synthetic modification strategies in the development of environmental remediation materials.