Moldable SnS2/polyimide aerogel as fixed-bed adsorbent: efficient immobilization of radioiodine vapor with resistance to high-temperature and high-humidity conditions

The effective capture of radioiodine vapor is of paramount importance in mitigating environmental radiation risks associated with spent fuel reprocessing, as well as for thyroid diagnosis and treatment. However, adsorbents used for iodine vapor capture are susceptible to the adverse effects of water vapor, leading to significant reductions in adsorption efficiency. This study presents the design and synthesis of polyimide (PI) aerogels integrated with in situ-grown SnS 2 through a hydrothermal approach. The shape of SnS 2 /PI aerogels can be adjusted via mold manipulation, while also possessing desirable mechanical strength. The SnS 2 /PI-2 aerogel exhibits a remarkable maximum adsorption capacity of 1167 mg/g in a dry environment, with only a marginal 12.4 % decrease observed in a high-humidity environment (74 % relative humidity, R.H.), as assessed by batch experiments. During application in the fixed-bed column, the SnS 2 /PI-2 aerogel demonstrates a significant adsorption capacity of 1070 mg/g at 75 °C. Monitoring conducted for 7 consecutive days post-adsorption confirms the absence of iodine release. This is attributed to the reduction of captured I 2 by the SnS 2 /PI-2 aerogel, forming the stable crystal SnI 4 , thereby preventing its release. Therefore, the SnS 2 /PI-2 aerogels exhibit excellent humidity resistance, thermal stability, and mechanical properties, rendering them highly suitable for capturing radioiodine vapor under complex conditions. This work offers insights into developing efficient aerogel adsorbents for treating radioactive iodine exhaust gases with high humidity in fixed-bed columns or decay tanks.