A recyclable covalent organic framework for selective removal of Hg(II) and sunlight-driven sterilization in water

Mercury ions (Hg²⁺) and bacteria are widely spread in water pollution and pose a great threat to human health and the environment. Herein, a multifunctional COF DmtaTph with significant Hg²⁺ adsorption capability and continuous sunlight-driven sterilization property is designed and synthesized by introducing thioether and photosensitive porphyrin in a single molecule. The obtained COF displays a high Hg²⁺ adsorption capacity of 657.9 mg/g at 298 K and a superior antibacterial effect toward Escherichia coli and Staphylococcus aureus under sunlight irradiation. Mechanistic studies reveal that the strong coordination between S species and Hg²⁺ is the main driving force for high Hg²⁺ adsorption capability. The sterilization mechanism clarifies that the inactivation of bacteria is caused by ¹O₂ produced from DmtaTph with the assistance of light irradiation. Noteworthy, when DmtaTph is applied in the treatment of wastewater, it displays high Hg²⁺ removal efficiency and remarkable antibacterial effect under complex conditions. This study has demonstrated a promising strategy for designing multifunctional COF-based materials, offering great potential in tackling the problem of heavy metal ions and bacteria pollution in water.