Speaker
Description
Radioiodine released during aqueous reprocessing must have high efficiency of capture due to environmental and safety reasons. There are various methods for capturing radioiodine such as caustic scrubbing, mercury nitrate solutions and solid sorbents. Each of these three techniques have different affinities for inorganic and organoiodines, but all radioiodine’s must be captured. Generally, organoiodines have a lower affinity with any of the techniques used compared to inorganic iodine.
Solid sorbents, such as silver zeolite, are known to have higher affinity for capturing organoiodines compared to the mercury nitrate solutions and caustic scrubbing. However, the affinity of organoiodines with solid sorbents is still lower than the affinity with inorganic iodine. Understanding the static capacity and morphological differences between inorganic iodine and organoiodines on solid sorbents can inform how to increase the organoiodine capacity. Studying how organidoines affinity differs from inorganic iodine can improve organoidoine affinity while reduce environmental impact.
In this experiment the mass ratio of analyte, either iodine or iodomethane, to silver zeolite was varied to obtain capacity curves and Scanning Electron Microscopy Energy Dispersive X-ray Spectroscopy (SEM-EDS) analyses at each ratio. The mass of analyte varied from 10% to 500% of the mass of sorbent. For each ratio, these data were obtained by placing three uncapped scintillation vials into a larger jar with a lid with ports. The scintillation vials contained a known mass of the sorbent and analyte with one vial left empty. The assembled jar containing the uncapped scintillation vials were placed in an oven at 150°C for two hours. After heating, the jar was removed and cooled, and each scintillation vial was weighed to find the mass difference. The mass difference of the sorbent vial was used to calculate the capacity at the given ratio for each analyte. The mass difference of the empty vial was used to determine any sorption of the analyte with the scintillation vial itself. Next, a few sorbent pieces were collected for SEM-EDS analysis. This process was repeated for all ratios of a given analyte and for iodine and iodomethane. The data collected show the differences in capacity and morphology between silver zeolite with inorganic iodine and organoiodine. The data collected are the first step in understanding the different interactions between these substances that can inform vital environmental questions.
Future work includes studying the stability of the sorbed analytes on the silver zeolite and performing dynamic testing.