Removal of Radioactive Iodine Species by Solid Sorbents

Iodine-129 is one of several radioactive iodine isotopes formed in fission reactions and it has a very long half-life of 16×10⁶ years. A variety of iodine-129 species are present in off-gases from spent nuclear fuel reprocessing facilities including I₂, CH3I, HI, higher molecular weight alkyl iodides, and others. Removal and immobilization of these species is one of a number of critical barriers to nuclear waste treatment. The current study will develop predictive models for simulating dynamic adsorption processes, and the results will be used to provide recommendations on a path forward for the development of sorbents and sorption processes for off-gas treatment. In this presentation, we will discuss the development of a continuous flow adsorption system which is being applied to study single-pellet adsorption dynamics. Kinetics of I₂ adsorption by silver-exchanged mordenite will be discussed.  Also, experimental studies on adsorption of various iodine species (I₂, CH₃I, C₂H₅I, etc.) by a number of sorbents (silver-exchanged mordenite, ZIF-8, etc.) will be discussed, and preliminary adsorption equilibrium data will be presented.