Evaluation of materials for iodine and technetium immobilization through sorption and redox-driven processes
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- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Soochow Univ., Suzhou (China)
- Lab. for Functional Inorganic Materials (EPFL), Sion (Switzerland)
- Monrovia, CA (United States)
Radioactive iodine-129 (129I) and technetium-99 (99Tc) pose a risk to groundwater due to their long half-lives, toxicity, and high environmental mobility. Based on literature reviewed in Moore et al. (2019) and Pearce et al. (2019), natural and engineered materials, including iron oxides, low-solubility sulfides, tin-based materials, bismuth-based materials, organoclays, and metal organic frameworks, were tested for potential use as a deployed technology for the treatment of 129I and 99Tc to reduce environmental mobility. Materials were evaluated with metrics including capacity for IO3– and TcO4– uptake, selectivity and long-term immobilization potential. Batch testing was used to determine IO3– and TcO4– sorption under aerobic conditions for each material in synthetic groundwater at different solution to solid ratios. Material association with IO3– and TcO4– was spatially resolved using scanning electron microscopy and X-ray microprobe mapping. The potential for redox reactions was assessed using X-ray absorption near edge structure spectroscopy. Of the materials tested, we report bismuth oxy(hydroxide) and ferrihydrite performed the best for IO3–. The commercial Purolite A530E anion-exchange resin outperformed all materials in its sorption capacity for TcO4–. Tin-based materials had high capacity for TcO4–, but immobilized TcO4– via reductive precipitation. Bismuth-based materials had high capacity for TcO4–, though slightly lower than the tin-based materials, but did not immobilize TcO4– by a redox-drive process, mitigating potential negative re-oxidation effects over longer time periods under oxic conditions. Cationic metal organic frameworks and polymer networks had high Tc removal capacity, with TcO4– trapped within the framework of the sorbent material. Although organoclays did not have the highest capacity for IO3– and TcO4– removal in batch experiments, they are available commercially in large quantities, are relatively low cost and have low environmental impact, so were investigated in column experiments, demonstrating scale-up and removal of IO3– and TcO4– via sorption, and reductive immobilization with iron- and sulfur-based species.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC05-76RL01830; AC02-06CH11357; NA0003525
- OSTI ID:
- 1638579
- Alternate ID(s):
- OSTI ID: 1632288
- Report Number(s):
- PNNL-SA-138462
- Journal Information:
- Science of the Total Environment, Vol. 716, Issue C; ISSN 0048-9697
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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