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Radiolytic alterations to neptunium extraction and redox in 30 % tri-n-butyl phosphate

  • Joshua R. Dunbar ORCID logo , Dean R. Peterman ORCID logo and Mark P. Jensen ORCID logo EMAIL logo
Published/Copyright: February 19, 2025
Radiochimica Acta
From the journal Radiochimica Acta Volume 113 Issue 5

Abstract

The extraction of neptunium in the +IV, +V, and +VI oxidation states was studied in irradiated solutions of 30 % tri-n-butyl phosphate (TBP) in dodecane as well as in synthetic mixtures of TBP with its primary radiolysis product, di-n-butyl phosphoric acid (HDBP). Extraction of all three oxidation states was increased by irradiation, with the most dramatic effect for Np(IV). Without stabilization of the neptunium oxidation state, the irradiated organic phase displayed redox activity toward the Np(VI/V) couple, achieving a Np(VI):Np(V) ratio set by absorbed dose, independent of starting oxidation state. In synthetic TBP-HDBP mixtures, Np(VI) was extracted better than in the irradiated case, while Np(IV) displayed similar behavior between the two systems. The presence of HDBP resulted in greater equilibrium Np(VI):Np(V) ratios when contacting a Np(V) solution in 4 M HNO3 with the synthetic mixture. Tetravalent neptunium also formed precipitates in the presence of HDBP at low acidities or high HDBP concentrations. All evidence points toward an ion-exchange extraction mechanism, where DBP−, rather than nitrate, coordinates to Np(IV) or Np(VI). Reductive stripping of Np(VI) from degraded organic phases using nitrous acid was unsuccessful, indicating that Np(VI) reduction is inhibited by the presence of HDBP.

Keywords: dibutyl phosphoric acid; extractant radiolysis; fuel reprocessing; neptunium redox chemistry; radiation effects; solvent extraction
Corresponding author: Mark P. Jensen, Chemistry Department, Colorado School of Mines, Golden, CO 80401, USA; and Nuclear Science & Engineering Program, Colorado School of Mines, Golden, CO 80401, USA, E-mail:

Funding source: U. S. Department of Energy, Office of Nuclear Energy

Award Identifier / Grant number: DE-NE0008942

Award Identifier / Grant number: DE-NE0009090

Award Identifier / Grant number: DE-AC07-05ID14517

Acknowledgments

This material is based upon work supported by the Department of Energy Office of Nuclear Energy under award Number DE-NE0008942. The work at the Idaho National Laboratory was performed under contract DE-AC07-05ID14517 with the direction of DRP. JRD acknowledges support as a fellow of the University Nuclear Leadership Program under award DE-NE0009090. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

  1. Research ethics: Not applicable.

  2. Informed consent: Not applicable.

  3. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  4. Use of Large Language Models, AI and Machine Learning Tools: None declared.

  5. Conflict of interest: The authors state no conflict of interest.

  6. Research funding: This material is based upon work supported by the Department of Energy Office of Nuclear Energy under award Number DE-NE0008942. The work at the Idaho National Laboratory was performed under contract DE-AC07-05ID14517. JRD acknowledges support as a fellow of the University Nuclear Leadership Program under award DE-NE0009090.

  7. Data availability: The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.

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Supplementary Material

This article contains supplementary material (https://doi.org/10.1515/ract-2024-0354).

Received: 2024-09-30
Accepted: 2025-01-24
Published Online: 2025-02-19
Published in Print: 2025-05-26

© 2025 Walter de Gruyter GmbH, Berlin/Boston

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https://doi.org/10.1515/ract-2024-0354
Keywords for this article
dibutyl phosphoric acid; extractant radiolysis; fuel reprocessing; neptunium redox chemistry; radiation effects; solvent extraction

Articles in the same Issue

  1. Frontmatter
  2. Original Papers
  3. An overview of production routes of the non-standard positron emitter 86gY with emphasis on a comparative analysis of the 86Sr(p,n)- and 86Sr(d,2n)-reactions
  4. Study on empirical formulae for (n,f) reaction cross sections of thorium isotopes between 1 and 20 MeV
  5. Radiolytic alterations to neptunium extraction and redox in 30 % tri-n-butyl phosphate
  6. Utilities of ionic liquid extraction with astatine ions and its extraction mechanism
  7. Gamma irradiation synthesis and characterization of Poly(N-vinyl-2-pyrrolidone/acrylic acid) superabsorbent hydrogels for treatment of ink waste
  8. Application of XRD, SEM-EDX and FTIR techniques for mineral characterization of geological ores
  9. Elucidating the effect of CdO–Na2O exchange on structure, mechanical and radiation shielding improvements of B2O3–P2O5–Na2O glass
  10. Alpha emitters concentration of natural radionuclides and lung cancer cases in blood of smokers and non-smokers using passive detector
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