2021 Volume 21 Pages 1-6
Silver doped zeolite (AgX) has attracted significant attention as a good adsorbent of organic iodine (CH3I) in the gas phase. Heat treatment of the adsorbent waste, which is composed of iodine-sorbed AgX, may be necessary for disposal, as iodine would be removed from AgX at high temperature. Therefore, the sorption and desorption behaviors of CH3I on AgX and zeolite X (13X) were investigated. Herein, CH3I labeled by a 125I tracer was synthesized via isotope exchange and used for sorption experiments on AgX. From the sorption experiment results, both labeled CH3125I and stable CH3I showed similar sorption behavior and nearly 100% of the CH3I was sorbed by 5 g of AgX at a flow rate lower than 0.08 m/s. Under high humidity conditions, AgX was soaked and decreased sorption performance was observed. However, after drying the soaked AgX, sorption performance recovered to the initial state. AgX exhibited higher holding performance for iodine than 13X, as almost all of the sorbed iodine was removed from 13X up to 500 °C. In contrast, it was confirmed that removal of the sorbed iodine from AgX was not observed until 830 °C.
