Methoxy Imine-Linked Covalent Organic Frameworks for Effective Iodine Adsorption in Gaseous and Aqueous Environments

Developing highly efficient adsorbents for radioactive iodine capture is crucial due to the severe environmental and health threats posed by isotopes like 129I and 131I. Here, we report a porous covalent organic framework, PyTTA-BD(OMe)2, featuring open one-dimensional channels and electron-donating methoxy groups. The strategic introduction of −OMe groups not only enhances the framework’s chemical stability but also optimizes its electronic affinity toward iodine species. PyTTA-BD(OMe)2 achieved an impressive iodine vapor uptake of 4.55 g g–1 and an I3– adsorption capacity of 1469 mg g–1 in aqueous solution, outperforming most reported adsorbents. Mechanism studies, including DFT and frontier molecular orbital (FMO) analysis, reveal that the high performance originates from the synergy of strong electrostatic affinities and pronounced charge-transfer interactions. With its excellent recyclability, selectivity, and potential for scalable synthesis, PyTTA-BD(OMe)2 represents a highly promising candidate for the treatment of complex radioactive iodine contamination in nuclear waste streams.