Speciation of Uranium in Solvent Extraction Systems Related to the ALSEP Process
Year: 2025
Type: article
Abstract: Climate changes dictate securing a reliable energy source with net-zero carbon oxide emission. An advanced nuclear fuel cycle would facilitate utilization of the nuclear energy. In order to better understand behavior of the used fuel components in advanced reprocessing schemes, the speciation of uranium relevant to the ALSEP process conditions has been studied. In particular, uranium(VI) in 3 M HNO3 was extracted by HEH[EHP] and/or T2EHDGA in dodecane and the speciation of U(VI) in the organic phases was analyzed using extended x-ray absorption fine structure (EXAFS) spectroscopy and Fourier-Transformed Infra-Red Spectroscopy. In the U(VI)-HNO3-HEH[EHP]-dodecane system, the EXAFS data suggested a mixture of UO2(A4) (30%) and UO2(NO3)2(H2A2) (70%) (A= EH[EHP]) where UO2(A4) collectively represents the species UO2(HA2)2, [UO2•2 H2A2][NO3]2 and a UO2(HA2)2/[UO2•2 H2A2][NO3]2 mixture. In the U(VI)-HNO3-T2EHDGA-dodecane system, EXAFS results were consistent with presence of UO2(NO3)2(T2EHDGA). in this case, the coordination number of the uranium for the first coordination sphere was found to be eight with one nitrate coordinated in a bidentate mode and another one coordinated in a monodentate mode. In the ALSEP mixed solvent conditions (U(VI)-HNO3-HEH[EHP]-T2EHDGA-dodecane system) EXAFS results indicated the presence of 60% UO2(NO3)2•H2A2 and 40% UO2(A4). The obtained results are compared with the literature data for other organophosphorus and diamide ligands.
Institution: University of Nevada, Las Vegas
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4407342020