Synthesis and thermodynamics of uranium-incorporated α-Fe2O3 nanoparticles

DOI: 10.1016/j.jnucmat.2021.153172

Authors: Andy Lam (University of California Davis) , Forrest Hyler (University of California Davis) , Olwen Stagg (The University of Manchester) , Katherine Morris (The University of Manchester) , Samuel Shaw (The University of Manchester) , Jesús M. Velázquez (University of California Davis) , Alexandra Navrotsky (University of California Davis; Arizona State University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Nuclear Materials , VOL 556

State: Published (Approved)
Published: December 2021
Diamond Proposal Number(s): 17243

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.

Journal Keywords: Uranyl; Iron oxides; Hematite; Water remediation; Calorimetry; X-ray absorption spectroscopy

Subject Areas: Materials, Chemistry, Environment


Instruments: B18-Core EXAFS

Discipline Tags:

Desertification & Pollution Earth Sciences & Environment Radioactive Materials Materials Engineering & Processes Physics Chemistry Material Sciences Engineering & Technology Nuclear Waste Nanoscience/Nanotechnology

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS)