| Autor: |
Finck N; Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT) , P.O. Box 3640, D-76021 Karlsruhe, Germany., Nedel S; Nano-Science Center, Department of Chemistry, University of Copenhagen , Universitetsparken 5, DK-2100 Copenhagen, Denmark., Dideriksen K; Nano-Science Center, Department of Chemistry, University of Copenhagen , Universitetsparken 5, DK-2100 Copenhagen, Denmark., Schlegel ML; CEA, DEN/DPC/SEARS/LISL, Building 391, F-91191 Gif-sur-Yvette, France. |
| Jazyk: |
angličtina |
| Zdroj: |
Environmental science & technology [Environ Sci Technol] 2016 Oct 04; Vol. 50 (19), pp. 10428-10436. Date of Electronic Publication: 2016 Sep 15. |
| DOI: |
10.1021/acs.est.6b02599 |
| Abstrakt: |
The retention of Am(III) by coprecipitation with or adsorption onto preformed magnetite was investigated by X-ray diffraction (XRD), solution chemistry, and X-ray absorption spectroscopy (XAS). In the coprecipitation experiment, XAS data indicated the presence of seven O atoms at 2.44(1) Å, and can be explained by an Am incorporation at Fe structural sites at the magnetite surface. Next-nearest Fe were detected at distances suggesting that Am and Fe polyhedra share corners in geometries ranging from bent to close to linear Am-O-Fe bonds. After aging for two years, the coordination number and the distance to the first O shell significantly decreased, and atomic shells were detected at higher distances. These data suggest a structural reorganization and an increase in structural order around sorbed Am. Upon contact with preformed Fe 3 O 4 , Am(III) forms surface complexes with cosorbed Fe at the surface of magnetite, a possible consequence of the high concentration of dissolved Fe. In a separate experiment, chloride green rust (GR) was synthesized in the presence of Am(III), and subsequently converted to Fe(OH) 2 (s) intermixed with magnetite. XAS data indicated that the actinide is successively located first at octahedral brucite-like sites in the GR precursor, then in Fe(OH) 2 (s), an environment markedly distinct from that of Am(III) in Fe 3 O 4 . The findings indicate that the magnetite formation pathway dictates the magnitude of Am(III) incorporation within this solid. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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