Metallic technetium sequestration in nickel core/shell microstructure during Fe(OH)2 transformation with Ni doping
SCIE
SCOPUS
- Title
- Metallic technetium sequestration in nickel core/shell microstructure during Fe(OH)2 transformation with Ni doping
- Authors
- Wang, Guohui; Kim, Dong-Sang; Olszta, Matthew J.; Bowden, Mark E.; Schreiber, Daniel K.; Saslow, Sarah A.; Um, Wooyong; Riley, Brian J.; Wang, Jing; Kruger, Albert A.
- Date Issued
- 2022-03-05
- Publisher
- Elsevier B.V.
- Abstract
- © 2021This study investigates the impacts of Ni doping on technetium-99 (Tc) sequestration in aqueous solutions through transformation of Fe(OH)2(s) to iron spinel (magnetite) under alkaline conditions. Extensive solid characterization was performed for the mineral phases produced, as well as the Tc/Ni speciation and distribution within these phases. X-ray diffraction results show that iron spinel was the dominant mineral product without detectable Ni incorporation. The doped Ni ions mainly precipitated as fine Fe/Ni oxide/hydroxide particles, including strongly reduced nanometer˗sized spheroidal Ni-rich and metallic Ni phases. High-resolution analytical scanning transmission electron microscopy using energy dispersive X-ray spectroscopy and electron energy loss spectroscopy on the produced solid samples (focused ion beam-prepared specimens) revealed three Tc distribution domains dominated by nanocrystals and, especially, a Tc-rich metallic phase. Instances of metallic Tc were specifically found in spheroidal, Ni-rich and metallic nanoparticles exhibiting a core/shell microstructure that suggests strong reduction and sequential precipitation of Ni-Tc-Ni. Mass balance analysis showed nearly 100% Tc removal from the 4.8 × 10−4 M Tc solutions. The finding of the metallic Tc encapsulation indicates that Tc sequestration through Ni-doped Fe(OH)2(s)˗to˗iron spinel transformation process likely provides an alternative treatment pathway for Tc removal and could be combined into further waste treatment approaches.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/110529
- DOI
- 10.1016/j.jhazmat.2021.127779
- ISSN
- 0304-3894
- Article Type
- Article
- Citation
- Journal of Hazardous Materials, vol. 425, 2022-03-05
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