Abstract: This study utilizes the fact that hydroxyl radicals generated under subcritical hydrothermal conditions can accelerate the reaction process. The iodosodalite was formed by treating homemade iodine-containing silver-containing silica gel with NaAlO₂ as raw material and adding 5 wt.% FD61 glass powder as an additive. The differences under static subcritical hydrothermal conditions and dynamic subcritical hydrothermal conditions were compared in the physical phase, microstructure and morphology of the iodosilicate synthesized. The XRD results showed that the dynamic subcritical hydrothermal conditions were favourable for the formation of iodosodalite due to the full contact between the solid phase and the liquid phase by the constant stirring. The SEM-EDS results show that the iodosodalite synthesized under the dynamic subcritical hydrothermal perform a homogeneous morphology with regular round flakes and the particle size about 2 μm. In the dynamic subcritical hydrothermal conditions, the iodine element is uniformly distributed in the solidification. The TG-DSC result shows that the synthesized solidified body has a good thermal stability, and can only decompose above 850 ℃. The XPS result shows that the elemental iodine in iodosodalite exists in the form of I^-. The present work could provide some theoretical references for low-temperature and rapid treatment of iodine-containing silver-coated silica gel under subcritical hydrothermal conditions.

Key words: iodosodalite, subcritical hydrothermal condition, silver-coated silica gel containing iodine, ceramic solidification