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 membrane, 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.