© 2020 Elsevier B.V. Cs3Bi2I9, a defect perovskite derivative, is a potential host phase to immobilize iodine and cesium with high waste loadings. In this work, two strategies were explored to form Cs3Bi2I9-silica composites and a core-shell structure in order to improve chemical durability of waste form materials meanwhile maintaining high waste loadings. Cs3Bi2I9 loadings as high as 70 wt.% were incorporated into a silica matrix to form silica-ceramic composites, and 20 wt.% Cs3Bi2I9 was encapsulated into silica to form a core–shell structure by low temperature spark plasma sintering. Chemical durability of the composite and core-shell waste forms was evaluated by semi-dynamic leaching experiments, and Cs and I were incongruently released from waste form matrices. A BiOI alteration layer formed, acting as a passivation layer to reduce the release of radionuclides. The long-term iodine release rate was low (30 mg m−2 day-1) for the 70 wt.% Cs3Bi2I9–silica composite leached in deionized water at 90 °C, which can be further reduced to 5 × 10−3 mg m−2 day−1 for the 20 wt.% core-shell structure. This work highlights a robust way to immobilize the highly mobile radionuclides with high waste loadings through encapsulation into durable matrices and a surface passivating mechanism that can greatly reduce the elemental transport from waste form materials and significantly enhance their chemical durability.
Publication Source (Journal or Book title)
Journal of Hazardous Materials
Yang, K., Zhu, W., Scott, S., Wang, Y., Wang, J., Riley, B., Vienna, J., & Lian, J. (2021). Immobilization of cesium and iodine into Cs3Bi2I9 perovskite-silica composites and core-shell waste forms with high waste loadings and chemical durability. Journal of Hazardous Materials, 401 https://doi.org/10.1016/j.jhazmat.2020.123279