Efficient and simultaneous capture of iodine and methyl iodide achieved by a covalent organic framework.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35610232.
- Also identified by DOI 10.1038/s41467-022-30663-3 and PMC identifier 9130143.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Radioactive molecular iodine (I<sub>2</sub>) and organic iodides, mainly methyl iodide (CH<sub>3</sub>I), coexist in the off-gas stream of nuclear power plants at low concentrations, whereas few adsorbents can effectively adsorb low-concentration I<sub>2</sub> and CH<sub>3</sub>I simultaneously. Here we demonstrate that the I<sub>2</sub> adsorption can occur on various adsorptive sites and be promoted through intermolecular interactions. The CH<sub>3</sub>I adsorption capacity is positively correlated with the content of strong binding sites but is unrelated to the textural properties of the adsorbent. These insights allow us to design a covalent organic framework to simultaneously capture I<sub>2</sub> and CH<sub>3</sub>I at low concentrations. The developed material, COF-TAPT, combines high crystallinity, a large surface area, and abundant nucleophilic groups and exhibits a record-high static CH<sub>3</sub>I adsorption capacity (1.53 g·g<sup>-1</sup> at 25 °C). In the dynamic mixed-gas adsorption with 150 ppm of I<sub>2</sub> and 50 ppm of CH<sub>3</sub>I, COF-TAPT presents an excellent total iodine capture capacity (1.51 g·g<sup>-1</sup>), surpassing various benchmark adsorbents. This work deepens the understanding of I<sub>2</sub>/CH<sub>3</sub>I adsorption mechanisms, providing guidance for the development of novel adsorbents for related applications.