Hybrid Sorbents for 129I Capture from Contaminated Groundwater

Elsa A Cordova; Vanessa Garayburu-Caruso; Carolyn I Pearce; Kirk J Cantrell; Joseph W Morad; Elizabeth C Gillispie; Brian J Riley; Ferdinan Cintron Colon; Tatiana G Levitskaia; Sarah A Saslow; Odeta Qafoku; Charles T Resch; Mark J Rigali; Jim E Szecsody; Steve M Heald; Mahalingam Balasubramanian; Peter Meyers; Vicky L Freedman

doi:10.1021/acsami.0c01527

Hybrid Sorbents for ¹²⁹I Capture from Contaminated Groundwater

ACS Appl Mater Interfaces. 2020 Jun 10;12(23):26113-26126. doi: 10.1021/acsami.0c01527. Epub 2020 Jun 1.

Authors

Elsa A Cordova¹, Vanessa Garayburu-Caruso¹, Carolyn I Pearce¹, Kirk J Cantrell¹, Joseph W Morad¹, Elizabeth C Gillispie¹, Brian J Riley¹, Ferdinan Cintron Colon¹, Tatiana G Levitskaia¹, Sarah A Saslow¹, Odeta Qafoku¹, Charles T Resch¹, Mark J Rigali², Jim E Szecsody¹, Steve M Heald³, Mahalingam Balasubramanian³, Peter Meyers⁴, Vicky L Freedman¹

Affiliations

¹ Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States.
² Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
³ Advanced Photon Source, Argonne National Laboratory, Argonne Illinois 60439, United States.
⁴ Resin Tech, West Berlin, New Jersey 08091, United States.

PMID: 32421326
DOI: 10.1021/acsami.0c01527

Abstract

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.

Keywords: bismuth oxyhydroxide; cerium oxide/oxyhydroxide; ferrihydrite; groundwater remediation; ion-exchange resins; polyacrylonitrile beads; radioiodine; silica substrates.