Highly efficient iodine capture by hydrophobic bismuth-based chrysotile membrane from humid gas streams

Because of their non-toxicity and low cost, bismuth-based materials have received considerable attention for the capture of gaseous iodine, especially for the removal of radioactive iodine in nuclear post-processing plants. In the actual operation conditions of reprocessing plant, the presence of water vapor must be considered as an important factor because it will significantly affect the iodine capturing efficiency for most iodine-capturing materials. To address this problem, we successfully synthesized a hydrophobic bismuth-based chrysotile mem-brane, which was modified by the silane coupling agent KH570. The chrysotile fiber was chosen to provide rich reactive sites for bismuth loading, and the bismuth was chosen due to its high affinity to iodine. The hydrophobic surface endowed by KH570 acts as a 'protecting layer' when water vapor exists during iodine adsorption. The maximum of iodine capture efficiency of the prepared membrane reached 483.37 mg/g in air, and 443.04 mg/g under 75 % relative humidity. Comparing hydrophobic membrane with one that non-modified by KH570, the hydrophobic membrane increases about 54 % iodine adsorption capacity in humid condition. This study provides a certain reference value for the application of bismuth-based materials in iodine removal under humid conditions.

Automated summary

Due to their non-toxicity and low cost, bismuth-based materials have attracted attention for the capture of gaseous iodine, especially in the removal of radioactive iodine in nuclear post-processing plants. However, the presence of water vapor in the reprocessing plant significantly affects the efficiency of iodine capture. To address this issue, a hydrophobic bismuth-based chrysotile membrane was successfully synthesized by modifying it with the silane coupling agent KH570. The hydrophobic surface provided by KH570 acts as a protective layer during iodine adsorption, resulting in an increased iodine capturing capacity in humid conditions.