Efficient and simultaneous capture of iodine and methyl iodide achieved by a covalent organic framework

Abstract

Radioactive molecular iodine (I2) and organic iodides, mainly methyl iodide (CH3I), coexist in the off-gas stream of nuclear power plants at low concentrations, whereas few adsorbents can effectively adsorb low-concentration I2 and CH3I simultaneously. Here we demonstrate that the I2 adsorption can occur on various adsorptive sites and be promoted through intermolecular interactions. The CH3I 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 I2 and CH3I 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 CH3I adsorption capacity (1.53 g·g−1 at 25 °C). In the dynamic mixed-gas adsorption with 150 ppm of I2 and 50 ppm of CH3I, COF-TAPT presents an excellent total iodine capture capacity (1.51 g·g−1), surpassing various benchmark adsorbents. This work deepens the understanding of I2/CH3I adsorption mechanisms, providing guidance for the development of novel adsorbents for related applications.

SuFEx‐Enabled Elastic Polysulfates for Efficient Removal of Radioactive Iodomethane and Polar Aprotic Organics through Weak Intermolecular Forces

“…After 20 hours, it was 1.573 times the original weight. This value is the highest adsorption capacity for iodomethane vapor reported to date (Figure 2c, Table S2) [12–15] . Moreover, the gel was easily recovered after adsorption.…”

“…However, the high cost of silver and the limited loading of silver atoms in zeolite hinder their large‐scale application [7–11] . Although many organic materials, including metal–organic frameworks (MOFs), [3, 12] porous organic polymers (POPs), [13] and covalent‐organic frameworks (COFs), [14, 15] provide large surface areas and abundant active sites for efficient iodomethane deposition, their complicated manufacturing processes and still limited deposition capacity prohibit their further application. In addition, polymeric adsorbents for iodomethane adsorption are mainly based on the chemical reaction between the iodomethane and their functional groups, resulting in poor recyclability.…”

SuFEx‐Enabled Elastic Polysulfates for Efficient Removal of Radioactive Iodomethane and Polar Aprotic Organics through Weak Intermolecular Forces

“…This value is the highest adsorption capacity for iodomethane vapor reported to date (Figure 2c, Table S2). [12][13][14][15] Moreover, the gel was easily recovered after adsorption. The recycling experiments showed that the adsorption capacity of iodomethane vapor decreased only slightly after five cycles, demonstrating good stability of the pyridine/TPC-cPS gel for adsorption and conversion of iodomethane vapor (Figure 2d).…”

“…However, the high cost of silver and the limited loading of silver atoms in zeolite hinder their large-scale application. [7][8][9][10][11] Although many organic materials, including metal-organic frameworks (MOFs), [3,12] porous organic polymers (POPs), [13] and covalent-organic frameworks (COFs), [14,15] provide large surface areas and abundant active sites for efficient iodomethane deposition, their complicated manufacturing processes and still limited deposition capacity prohibit their further application. In addition, polymeric adsorbents for iodomethane adsorption are mainly based on the chemical reaction between the iodomethane and their functional groups, resulting in poor recyclability.…”

Hydrogen‐Bonded Organic Framework for High‐Performance Lithium/Sodium‐Iodine Organic Batteries

“…[15][16][17][18][19][20] Therefore, new attempts are designed to explore new matrix materials to have an affinity with iodine and solve the critical problem with iodine organic batteries. [21] Porous materials, or porous media, have long been iodine-hosted materials and explored by scientists worldwide. Hydrogen-bonded organic frameworks (HOF) are potential materials with a low-cost, recyclable, mental-free nature, less exothermic advantages, and more straightforward connectivity options.…”