August 1, 2013.
Several subsurface water plumes are found at the Hanford U.S. DOE site. These plumes contain many different types of hazardous components including radioactive iodate (IO3-) and iodide (I-), which may have deleterious health effects. To selectively uptake IO3- and I-, inorganic layered double hydroxide (LDH) compounds were synthesized and tested. LDHs are mixed transition metal hydroxides that contain positively charged layers that undergo anion exchange. When LDHs are submerged in the plume water, they can selectively uptake IO3- and I- and remove them from the plume. Raman spectroscopy was used to monitor the uptake of IO3- and I-. The thermodynamic properties of the LDHs were determined by differential scanning calorimetry (DSC), where a phase transition was observed in the thermogram of each LDH compound. The thermodynamic properties describe the temperature range where the LDH compounds are stable and uptake the highest concentration of IO3- and I-. Raman spectroscopy indicated which LDH compounds were the most selective for IO3-. Further experiments will be performed to determine IO3- and I- sorption of LDH compounds in groundwater. Similar technology can then be applied to radioactive waste where interferences from other compounds are present.
Analytical Chemistry | Inorganic Chemistry | Physical Chemistry
Pacific Northwest National Laboratory (PNNL)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013 and Grant No. 0833353. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).