Polyacrylonitrile-chalcogel hybrid sorbents for radioiodine capture

Powders of a Sn₂S₃ chalcogen-based aerogel (chalcogel) were combined with powdered polyacrylonitrile (PAN) in different mass ratios (SnS₃₃, SnS₅₀, and SnS₇₀; # = mass% of chalcogel), dissolved in dimethyl sulfoxide, and added dropwise to deionized water to form pellets of a porous PAN-chalcogel hybrid material. These pellets, along with pure powdered (SnS_p) and granular (SnS_g) forms of the chalcogel, were then used to capture iodine gas under both dynamic (dilute) and static (concentrated) conditions. Both SnS_p and SnS _g chalcogels showed very high iodine loadings at 67.2 and 68.3 mass%, respectively. The SnS₅₀ hybrid sorbent demonstrated a high, although slightly reduced, maximum iodine loading (53.5 mass%) with greatly improved mechanical rigidity. In all cases, X-ray diffraction results showed the formation of crystalline SnI₄ and SnI₄(S₈) ₂, revealing that the iodine binding in these materials is mainly due to a chemisorption process, although a small amount of physisorption was observed.