Systematic modulation of thiol functionalities in inexpensive porous polymers for effective mercury removal

Mercury (Hg) contamination in aquatic systems still poses serious health risks through accumulation despite the strict regulations on drinking water and industrial discharge. One effective strategy is adsorptive removal, where a suitably functionalized porous material is added to water treatment protocols. Thiol (SH) group grafted structures perform commendably without due attention to the cost, scalability, and reusability and how the arrangement of sulfur atoms could affect the Hg (II) binding strength. We use an inexpensive and scalable porous covalent organic polymer (COP-130) to systematically introduce thiol functional groups with precise chain lengths and sulfur content. The thiol-functionalized COP-130 demonstrates enhanced wettability and excellent Hg (II) uptake up to 936 mg g-1, with fast kinetics and exceptionally high selectivity. These Hg adsorbents are easily regenerated with HCl and used at least six times even after strong acid treatments without loss of capacity, a rare performance in the Hg removal research domain.