Structural determination of Np(VII) compounds under alkaline conditions
- Los Alamos National Lab., NM (United States); and others
Highly alkaline radioactive wastes exist containing significant quantities of actinides (U, Np, Pu, Am) in storage tanks at many nuclear facilities in the U.S. Under strong alkaline conditions ([OH]=2-14 M), high oxidation states of the actinides can be stabilized. It is not known what effect the higher oxidation states may have on the separation, treatment, and disposal of the waste. Since Np(VII) is an ion of potential concern we have begun to determine the structures of its aqueous and solid state species using UV-Vis, IR, EXAFS, RAMAN, and {sup 17}O-NMR spectroscopies. Solids of the formula M{sub x}NpO{sub 4}(OH){sub 2}{center_dot}nH{sub 2}O (where M is a counter ion, such as Na{sup +}, Cs{sup +}, or [Co(NH{sub 3}){sub 6}]{sup +}), which display an unusual tetragonal bipyramidal NpO{sub 4}(OH){sub 2}{sup 3-} central core have been reported. It has been proposed that the NpO{sub 4}(OH){sub 2}{sup 3-} anion is also present in solution, however EXAFS analysis of Np(VII) in 2.5 M NaOH indicates a trans-dioxo ion, NpO{sub 2}{sup 3+}, as the central cation. These results and additional spectroscopic data will be presented.
- OSTI ID:
- 559901
- Report Number(s):
- CONF-970443-; TRN: 98:002128
- Resource Relation:
- Conference: 213. national meeting of the American Chemical Society, San Francisco, CA (United States), 13-17 Apr 1997; Other Information: PBD: 1997; Related Information: Is Part Of 213th ACS national meeting; PB: 2904 p.
- Country of Publication:
- United States
- Language:
- English
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