Hybrid Sorbents for 129I Capture from Contaminated Groundwater

• Published in: ACS applied materials & interfaces Vol. 12; no. 23
• Main Authors: Cordova, Elsa A., Garayburu-Caruso, Vanessa, Pearce, Carolyn I., Cantrell, Kirk J., Morad, Joseph W., Gillispie, Elizabeth C., Riley, Brian J., Colon, Ferdinan Cintron, Levitskaia, Tatiana G., Saslow, Sarah A., Qafoku, Odeta, Resch, Charles T., Rigali, Mark J., Szecsody, Jim E., Heald, Steve M., Balasubramanian, Mahalingam, Meyers, Peter, Freedman, Vicky L.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society (ACS) 18-05-2020
• Subjects: bismuth oxyhydroxide; cerium oxide/oxyhydroxide; ENVIRONMENTAL SCIENCES; ferrihydrite; groundwater remediation; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ion-exchange resins; polyacrylonitrile beads; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; radioiodine; silica substrates
• ISSN: 1944-8244; 1944-8252

Radioiodine (129I) poses a risk to the environment due to its long half-life, toxicity, and mobility. It is found at the U.S. Department of Energy Hanford Site due to legacy releases of nuclear wastes to the subsurface where 129I is predominantly present as iodate (IO3–). To date, a cost-effective and scalable cleanup technology for 129I has not been identified, with hydraulic containment implemented as the remedial approach. Here, novel high-performing sorbents for 129I remediation with the capacity to reduce 129I concentrations to or below the US Environmental Protection Agency (EPA) drinking water standard and procedures to deploy them in an ex-situ pump and treat (P&T) system are introduced. This includes implementation of hybridized polyacrylonitrile (PAN) beads for ex-situ remediation of IO3–-contaminated groundwater for the first time. Iron (Fe) oxyhydroxide and bismuth (Bi) oxyhydroxide sorbents were deployed on silica substrates or encapsulated in porous PAN beads. In addition, Fe–, cerium (Ce)–, and Bi–oxyhydroxides were encapsulated with anion-exchange resins. The PAN–bismuth oxyhydroxide and PAN–ferrihydrite composites along with Fe- and Ce-based hybrid anion-exchange resins performed well in batch sorption experiments with distribution coefficients for IO3– of >1000 mL/g and rapid removal kinetics. Of the tested materials, the Ce-based hybrid anion-exchange resin was the most efficient for removal of IO3– from Hanford groundwater in a column system, with 50% breakthrough occurring at 324 pore volumes. The functional amine groups on the parent resin and amount of active sorbent in the resin can be customized to improve the iodine loading capacity. These results highlight the potential for IO3– remediation by hybrid sorbents and represent a benchmark for the implementation of commercially available materials to meet EPA standards for cleanup of 129I in a large-scale P&T system.