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

•Spherical vinyl-functional COF-V exhibits 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 NaI in aqueous solution.•More than 90% Na131I is removed from aqueous solutions ranging from 181.3 MBq to 1017.5 MBq.•Spherical vinyl-functional COF-V with 1D channels facilitates the osmotic diffusion and adsorption of iodide ions in aqueous solutions in mesoporous pores, which plays a crucial role in the uptake of iodide ions.•The benzene C-H···I−1 hydrogen bonding between iodide ions and the two benzene rings connected by imine bonds and vinyl groups also promotes the efficient capture of NaI by spherical COF-V.