# Efficient iodine capture from water using a functionalized covalent organic framework

## TL;DR

A new material captures large amounts of iodine from water efficiently and can be reused multiple times.

## Contribution

Functionalizing COF-366 with amidoxime groups creates a highly reusable and high-capacity iodine adsorbent.

## Key findings

- POP-AO achieved an iodine uptake of 909.1 mg g−1, outperforming many existing materials.
- The material's high capacity is due to Lewis acid–base interactions between amidoxime groups and iodine.
- POP-AO retained its performance after seven regeneration cycles, showing excellent reusability.

## Abstract

The development of effective iodine adsorbents is a vital and challenging goal in radioactive waste management. In this study, we functionalized a covalent organic framework (COF-366) with amidoxime groups (AO) to create a new porous organic polymer (POP-AO), designed specifically for iodine capture. We systematically examined several key factors, including contact time, pH, initial iodine concentration, and the effect of competing ions on adsorption performance. Notably, POP-AO achieved an impressive iodine uptake of 909.1 mg g−1, exceeding many previously reported materials. This high capacity mainly results from Lewis acid–base interactions between the electron-rich AO groups and electrophilic iodine. Kinetic studies indicated that the adsorption follows a pseudo-second-order model. Moreover, the material maintained its high capacity of 909.1 mg g−1 after seven regeneration cycles, demonstrating excellent reusability. This research not only offers a promising strategy for radioactive iodine remediation but also establishes POP-AO as a durable and effective adsorbent for practical use.

An amidoxime-functionalized COF-366 enables ultrafast, high-capacity molecular iodine capture from water (909.1 mg g−1), driven by charge-transfer interactions, with excellent reusability over seven cycles.