ABSTRACT
The development of functionalized covalent organic frameworks (COFs) is crucial in expanding their potential for removing toxic heavy metals from drinking water. Here, a new sulfhydryl-modified heteroporous COF (COFDBD-BTA) was prepared using a "bottom-up" approach in which a direct amine-aldehyde dehydration condensation between 2,5-diamino-1,4-benzenedithiol dihydrochloride (DBD) and [1,1'-biphenyl]-3,3',5,5'-tetracarbaldehyde (BTA) was occurred. The COFDBD-BTA featured a hexagonal kagome (kgm) structure and a sheet-like morphology. Notably, COFDBD-BTA contained densely S atoms that provided high-density Hg(II) adsorption sites for efficient and selective trace Hg(II) removal. COFDBD-BTA exhibited excellent performance in rapidly removing trace Hg(II) from 30 µg L-1 to 0.71 µg L-1 within 10 s, below the World Health Organization's allowable limit of 1 µg L-1. Additionally, COFDBD-BTA exhibited a high Hg (â ¡) removal level from water, achieving adsorption capacity of 687.38 mg g-1. Furthermore, the adsorbent exhibited a wide range of applicability for low concentration (6-500 µg L-1) Hg (â ¡), a simple and feasible regeneration method, and strong Hg(II) removal ability in real tap water systems. The excellent adsorption efficiency, outstanding recyclability, and one-step room temperature synthesis make S-rich COFDBD-BTA a promising candidate for eliminating Hg (â ¡) from drinking water.