This research is from Nat. Commun. 2022, 13, 2878, completed by Professor Yu Han from KAUST.

Abstract
1) The coexistence of radioactive molecular iodine (I2) and organic iodides, such as methyl iodide (CH3I), in nuclear plant off-gases presents a significant adsorption challenge, as few materials can capture both at low concentrations effectively. This study demonstrates a covalent organic framework (COF) that can simultaneously adsorb I2 and CH3I, leveraging various adsorptive sites and intermolecular interactions for I2, and a correlation between CH3I adsorption capacity and strong binding sites for CH3I.
2) The developed COF-TAPT material showcases high crystallinity, large surface area, and abundant nucleophilic groups, achieving a record-high static CH3I adsorption capacity of 1.53 g·g−1 at 25 °C. In dynamic mixed-gas adsorption tests with 150 ppm I2 and 50 ppm CH3I, COF-TAPT demonstrated a superior total iodine capture capacity of 1.51 g·g−1, surpassing benchmark adsorbents.
3) This work advances the understanding of I2/CH3I adsorption mechanisms and provides guidance for developing novel adsorbents, highlighting the significance of nucleophilic N sites for CH3I capture and the role of various sites for I2 adsorption.

Research Background
1) Industry Problems: Traditional air catalytic oxidation processes for PMDA oxidation in the production of PI materials are outdated and inefficient, with low selectivity and high temperatures required, leading to low yields, low purity, and high costs.
2) Innovative Ideas: The authors propose the development of a high-selectivity air catalytic oxidation process to improve the production of PI materials, focusing on green, safe, and efficient oxidation services for various industries.

Experimental Details
1) Synthesis of COFs: Two COFs, COF-TAPB and COF-TAPT, were synthesized for the simultaneous capture of I2 and CH3I. The synthesis involved the reaction of specific monomers to form imine linkages, resulting in materials with high crystallinity and designed structures.
2) Adsorption Tests: Both static and dynamic adsorption tests were conducted under various conditions to evaluate the performance of COFs in capturing I2 and CH3I. The tests included high-concentration static adsorption, dynamic adsorption at different temperatures, and low-concentration dynamic adsorption simulating practical off-gas treatment.
3) Material Characterization: The synthesized COFs were characterized using PXRD, N2 sorption isotherms, FTIR, and other techniques to confirm their structure, surface area, and porosity.

Results & Analysis
1) Characterization Results: COF-TAPT and COF-TAPB were confirmed to be highly crystalline with large surface areas and similar textural properties, but COF-TAPT had a higher N content, which was crucial for CH3I adsorption.
2) Adsorption Performance: COF-TAPT exhibited superior adsorption capacities for both I2 and CH3I under various conditions, with a particularly high capacity in low-concentration dynamic adsorption tests.
3) Regenerability: The adsorbed I2 and CH3I could be efficiently extracted from COF-TAPT using ethanol, allowing for multiple adsorption/regeneration cycles.

Conclusion
1) The study successfully developed COF-TAPT, a high-performance adsorbent for the simultaneous capture of I2 and CH3I, demonstrating record-high adsorption capacities and excellent regenerability.
2) The findings emphasize the importance of nucleophilic N sites for CH3I capture and the role of various adsorptive sites for I2, providing a basis for the design of advanced adsorbents.
3) COF-TAPT's performance surpasses existing adsorbents, offering a promising solution for the treatment of off-gases from nuclear power plants and other applications.
4) It is recommended that the authors explore the scalability of the synthesis process for industrial application and investigate the potential of COF-TAPT for capturing other volatile organic compounds in addition to iodine species.

Efficient and simultaneous capture of iodine and methyl iodide achieved by a covalent organic framework
Yaqiang Xie, Tingting Pan, Qiong Lei, Cailing Chen, Xinglong Dong, Youyou Yuan, Walid Al Maksoud, Long Zhao, Luigi Cavallo, Ingo Pinnau & Yu Han
DOI: 10.1038/s41467-022-30663-3
Link: https://www.nature.com/articles/s41467-022-30663-3