Core-shell structured Bi2S3-ZnS@C derived from ZIF-8 for efficient capture and reliable storage of volatile radioactive iodine

Effective capture of radioiodine is crucial for the sustainable development of nuclear power, given its environmental mobility, high toxicity, and long half-life. Herein, a new core-shell structured Bi2S3-ZnS@C derived from ZIF-8 was synthesized by cation exchange, sulfation and carbonization. The advantage of this structure is that Bi2S3 uniformly loads on the surface of nanoparticles, effectively avoiding its aggregation and improving the utilization of active sites. The iodine capture experiments indicated that Bi2S3-ZnS@C had excellent adsorption capacity (up to 1118.5 mg g-1 within 120 min) and high chemisorption percentage (87.3 %) at 200 degrees C, as well as superior thermal and irradiation stability. The mechanism investigations revealed that the exceptional iodine uptake performance was predominantly attributed to the strong chemical reaction between Bi2S3 and I2 to generate BiI3. Additionally, the iodine-captured Bi2S3-ZnS@C could be immobilized in a commercial glass composition via low-temperature sintering. The findings indicated that the captured BiI3 and I2 were efficiently converted to the chemically stable BixOyI during the sintering process. The initial leaching rate of iodine was 3.94 x 10-5 g m- 2 d-1 , which signified the excellent chemical durability of the resultant glass composites. Therefore, the obtained Bi2S3-ZnS@C could be a promising candidate for efficient capture and stable storage of radioiodine.