Synthesis and thermodynamics of uranium-incorporated α-Fe2O3 nanoparticles

Andy Lam, Forrest Hyler, Olwen Stagg, Katherine Morris, Samuel Shaw, Jesús M. Velázquez, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

Abstract

Hematite nanoparticles were synthesized with U(VI) in circumneutral water through a coprecipitation and hydrothermal treatment process. XRD, TEM, and EXAFS analyses reveal that uranium may aggregate along grain boundaries and occupy Fe sites within hematite. The described synthesis method produces crystalline, single-phase iron oxide nanoparticles absent of surface-bound uranyl complexes. EXAFS data were comparable to spectra from existing studies whose syntheses were more representative of naturally occurring, extended aging processes. This work provides and validates an accelerated method of synthesizing uranium-immobilized iron oxide nanoparticles for further mechanistic studies. High temperature oxide melt solution calorimetry measurements were performed to calculate the thermodynamic stability of uranium-incorporated iron oxide nanoparticles. Increasing uranium content within hematite resulted in more positive formation enthalpies. Standard formation enthalpies of UxFe2–2xO3 were as high as 76.88 ± 2.83 kJ/mol relative to their binary oxides, or -764.04 ± 3.74 kJ/mol relative to their constituent elements, at x = 0.037. Data on the thermodynamic stability of uranium retention pathways may assist in predicting waste uranyl remobilization, as well as in developing more effective methods to retain uranium captured from aqueous environments.

Original languageEnglish (US)
Article number153172
JournalJournal of Nuclear Materials
Volume556
DOIs
StatePublished - Dec 1 2021

Keywords

  • Calorimetry
  • Hematite
  • Iron oxides
  • Uranyl
  • Water remediation
  • X-ray absorption spectroscopy

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Materials Science(all)
  • Nuclear Energy and Engineering

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