Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1021/acs.inorgchem.9b02463
Document author version
Title (Primary) Competitive reaction of neptunium(V) and uranium(VI) in potassium−sodium carbonate-rich aqueous media: Speciation study with a focus on high-resolution X‑ray spectroscopy
Author Vitova, T.; Pidchenko, I.; Schild, D.; Prüßmann, T.; Montoya, V.; Fellhauer, D.; Gaona, X.; Bohnert, E.; Rothe, J.; Baker, R.J.; Geckeis, H.
Source Titel Inorganic Chemistry
Year 2020
Department ENVINF
Volume 59
Issue 1
Page From 8
Page To 22
Language englisch
Supplements https://pubs.acs.org/doi/suppl/10.1021/acs.inorgchem.9b02463/suppl_file/ic9b02463_si_001.pdf
Abstract Neptunium(V) and uranium(VI) are precipitated from an aqueous potassium–sodium-containing carbonate-rich solution, and the solid phases are investigated. U/Np M4,5-edge high-energy resolution X-ray absorption near edge structure (HR-XANES) spectroscopy and Np 3d4f resonant inelastic X-ray scattering (3d4f RIXS) are applied in combination with thermodynamic calculations, U/Np L3-edge XANES, and extended X-ray absorption fine structure (EXAFS) studies to analyze the local atomic coordination and oxidation states of uranium and neptunium. The XANES/HR-XANES analyses are supported by ab initio quantum-chemical computations with the finite difference method near-edge structure code (FDMNES). The solid precipitates are also investigated with powder X-ray diffraction, scanning electron microscopy–energy dispersive X-ray spectroscopy, and Raman spectroscopy. The results strongly suggest that K[NpVO2CO3](cr), K3[NpVO2(CO3)2](cr), and K3Na[UVIO2(CO3)3](cr) are the predominant neptunium and uranium solid phases formed. Despite the 100 times lower initial neptunium(V) concentration at pH 10.5 and oxic conditions, neptunium(V)-rich phases predominately precipitate. The prevailing formation of neptunium(V) over uranium(VI) solids demonstrates the high structural stability of neptunium(V) carbonates containing potassium. It is illustrated that the Np M5-edge HR-XANES spectra are sensitive to changes of the Np–O axial bond length for neptunyl(V/VI).
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=22567
Vitova, T., Pidchenko, I., Schild, D., Prüßmann, T., Montoya, V., Fellhauer, D., Gaona, X., Bohnert, E., Rothe, J., Baker, R.J., Geckeis, H. (2020):
Competitive reaction of neptunium(V) and uranium(VI) in potassium−sodium carbonate-rich aqueous media: Speciation study with a focus on high-resolution X‑ray spectroscopy
Inorg. Chem. 59 (1), 8 - 22 10.1021/acs.inorgchem.9b02463