Vinyl-functionalized covalent organic frameworks for effective radioactive iodine capture in aqueous solution

I-131 radioisotopes have been widely employed in diagnostic and therapeutic medicine processes, particularly for thyroid cancer. The radiation hazard of I-131 offers a potential threat to environmental safety or human health, so the wastewater generated from the production of I-131 drugs must be effluent disposed of on time. In this study, we developed novel vinyl-functionalized covalent organic frameworks (COFs) with large pore volume and internal surface area for highly effective radioactive iodine ions adsorption in water. The as-produced spherical COFs (COF-V) exhibited a rapid adsorption rate (0.318 g g(-1) min(-1)) and exceptionally high adsorption capacity of up to 437.8 mg g(-1) for iodine ions in water. Furthermore, it demonstrated more than 90% removal of (NaI)-I-131 in water with radiation doses ranging from 181.3 MBq (4.9 mCi) to 1017.5 MBq (27.5 mCi). Additional characterizations and density functional theory (DFT) calculations revealed that the vinyl groups were linked with a benzene ring and imine to form a large and complete pi-pi conjugate system with 1D open channels. These channels provided sufficient sites for the effective adsorption of I ions on vinyl groups and benzene rings through hydrogen bonding. The excellent adsorption performance and radiation stability make the developed spherical COF-V a promising candidate for efficient radioactive iodine removal in wastewater.