Local Charge Density Enhancement Strategy in Nitrogen‐rich Covalent Organic Framework for Boosted Iodine Removal From Water

The leakage of nuclear pollution highlights the critical importance of effectively separating radioactive pollutants. Radioactive iodine, a high-yield fission product of nuclear reactions, poses serious environmental and health risks. However, the lack of efficient adsorbents makes the management of aqueous radioactive iodine pollution a significant challenge. N-doped materials are among the most recognized adsorbents for iodine removal, but their weak binding affinity and limited number of iodine-binding N-sites hinder their practical application. Herein, a covalent organic framework (COFs) named phen-TPA is synthesized, featuring an increased number and optimized local chemical environment of iodine-binding N-sites. This material demonstrates record-breaking iodine removal kinetics, with a kinetic constant of 14.64 g g^-1 min^-1 for aqueous iodine (I₂), and the highest-reported iodine adsorption capacity of 11.9 g g^-1 for aqueous triiodide (I₃ ^-). Large-scale flow-through adsorption experiments show that phen-TPA can remove 99.5% aqueous I₂ and I₃ ^- from high-salinity aqueous environments, highlighting its potential for practical applications.