Environmental applications of XANES: Speciation of {Tc} in cement after chemical treatment and Se after bacterial uptake
- and others
XANES (X-ray Absorption Near Edge Spectroscopy) has been employed to evaluate the efficacy of a process designed to encapsulate and reduce {Tc}O{sub 4}{sup {minus}} in cement matrices, thereby immobilizing {Tc}. The oxidation state of Se following.bioremediation of Se by bacteria has also been determined by XANES. The XANES measurements were performed at the Stanford Synchrotron Radiation Laboratory (SSRL) and the National Synchrotron Light Source (NSLS) at the respective K edges of {Tc} (21.0 keV) and Se (12.7 keV). Comparison of the XANES spectra of Tc in untreated cement to Tc in slag treated cement and to the chemical shifts of reference materials, shows that the oxidation state of {Tc} is the same in both cements. Thus, the addition of a reducing agent to the cement formulation does not significantly reduce the {Tc}O{sub 4} The common soil bacterium, Bacillus subtilis, is known to incorporate Se on or within the cell wall when exposed to a SE(IV) solution. The Se XANES spectra of B. subtilis, as well as bacillus isolated from selenium rich soil, show that the organisms reduce selenite to the red allotrope of elemental Se.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098; AC09-76SR00819
- OSTI ID:
- 93770
- Report Number(s):
- LBL-35411; CONF-940411-56; ON: DE95012364; TRN: 95:018433
- Resource Relation:
- Conference: Spring meeting of the Materials Research Society (MRS), San Francisco, CA (United States), 4-8 Apr 1994; Other Information: PBD: Mar 1994
- Country of Publication:
- United States
- Language:
- English
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