Plutonium(IV) sorption during ferrihydrite nanoparticle formation

Research output: Contribution to journalArticlepeer-review

  • External authors:
  • Kurt F Smith
  • Gareth T.w. Law
  • Ellen Winstanley
  • Joshua Simon Weatherill
  • Liam Abrahamsen-mills
  • Nicholas Bryan
  • J. Frederick Willem Mosselmans
  • Giannantonio Cibin
  • Stephen Parry
  • Richard Blackham
  • Kathleen Law

Abstract

Understanding interactions between iron (oxyhydr)oxide nanoparticles and plutonium is essential to underpin technology to treat radioactive effluents, in clean-up of land contaminated with radionuclides, and to ensure the safe disposal of radioactive wastes. These interactions include a range of adsorption, precipitation and incorporation processes. Here, we explore the mechanisms of plutonium sequestration during ferrihydrite precipitation from an acidic solution. The initial 1 M HNO3 solution with Fe(III)(aq) and 242Pu(IV)(aq) underwent controlled hydrolysis via the addition of NaOH to pH 9. The majority of Fe(III)(aq) and Pu(IV)(aq) was removed from solution between pH 2 and 3 during ferrihydrite formation. Analysis of Pu-ferrihydrite by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy showed that Pu(IV) formed an inner sphere tetradentate complex on the ferrihydrite surface, with minor amounts of PuO2 present. Best fits to the EXAFS data collected from Pu-ferrihydrite samples aged for two- and six- months showed no statistically significant change in the Pu(IV)-Fe oxyhydroxide surface complex despite the ferrihydrite undergoing extensive recrystallisation to hematite. This suggests the Pu remains strongly sorbed to the iron (oxyhydr)oxide surface and could be retained over extended time periods.

Bibliographical metadata

Original languageEnglish
Pages (from-to)2437-2442
JournalACS Earth and Space Chemistry
Volume3
Issue number11
Early online date16 Sep 2019
DOIs
Publication statusPublished - 16 Sep 2019

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