XAFS investigation of the interactions of uranium (VI) with secondary mineralization products from the bioreduction of iron (III) oxides.
- Biosciences Division
Biogenic Fe{sup II} phases (magnetite, green rust, siderite, vivianite, etc.) provide a reservoir of reducing capacity in many subsurface environments that may contribute to the reduction of contaminants such as U{sup VI}. We have examined the uptake and reduction of U{sup VI} in the presence of biogenic green rust (BioGR), magnetite (BioMAG), and siderite (BioSID) formed during the reduction of Fe{sup III} oxides by Shewanella putrefaciens CN32. Within 48 h, total solution-phase U{sup VI} concentrations decreased from 500{mu}M to 1.5{mu}M, 392{mu}M, and 472{mu}M in the U-BioGR, U-BioMAG, and U-BioSID systems, respectively. Analysis of the samples by U L{sub III} extended X-ray absorption fine structure spectroscopy (EXAFS) indicated that despite a stoichiometric excess of Fe{sup II}, no more than 6% of U{sup VI} was reduced to U{sup IV} in the U-BioSID system, and no more than 22% of U{sup VI} was reduced in the U-BioMAG system. For comparison, in the U-BioGR system, >99% of U{sup VI} was reduced to U{sup IV}. Uptake of U{sup VI} by BioGR and BioMAG was accompanied by formation of nanoparticulate uraninite. The U EXAFS data for the U-BioSID system were consistent with partial U{sup VI}/U{sup IV} substitution for Fe{sup II} in the surface layer of siderite particles and adsorption of U{sup IV}.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1026628
- Report Number(s):
- ANL/BIO/JA-65197
- Journal Information:
- Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 5 Vol. 44; ISSN ESTHAG; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- ENGLISH
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