Environmental applications of XANES: Speciation of Tc in cement after chemical treatment and Se after bacterial uptake

Conference · Sat Dec 31 00:00:00 EST 1994

OSTI ID:106203

Shuh, D K; Kaltsoyannis, N; Bucher, J J ^[1]

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1. Lawrence Berkeley Lab., CA (United States). Chemical Sciences Div.; and others

XANES (X-ray Absorption Near Edge Spectroscopy) has been employed to evaluate the efficacy of a process designed to encapsulate and reduce TcO{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 TcO{sub 4}{sup {minus}}. 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. The first investigation was to evaluate the effectiveness of a chemical reaction designed to slow the release of {sup 99}TcO{sub 4}{sup {minus}} in nuclear wasteform cements. The second investigation was to characterize the oxidation state of Se after microbial uptake from an aqueous solution by common soil bacteria, in order to provide information about the possible mechanisms of bioremediation.

• DOE Contract Number: AC03-76SF00098; AC09-76SR00819
• OSTI ID: 106203
• Report Number(s): CONF-940411-; ISBN 1-55899-239-1; TRN: 95:020714
• Resource Relation: Conference: Spring meeting of the Materials Research Society (MRS), San Francisco, CA (United States), 4-8 Apr 1994; Other Information: PBD: 1994; Related Information: Is Part Of Materials and processes for environmental protection; Voss, K.E.; Quick, L.M. [eds.] [Englehard Corp., Iselin, NJ (United States)]; Gadgil, P.N. [ed.] [Queens Univ., Kingston, Ontario (Canada)]; Adkins, C.L.J. [ed.] [Sandia National Labs., Albuquerque, NM (United States)]; PB: 356 p.; Materials Research Society symposium proceedings, Volume 344
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
TECHNETIUM
X-RAY SPECTROSCOPY
ABSORPTION SPECTROSCOPY
SELENIUM
WASTE FORMS
CHEMICAL ANALYSIS
SELENIUM COMPOUNDS
BIODEGRADATION
TECHNETIUM OXIDES
SOLIDIFICATION
RADIOACTIVE WASTE DISPOSAL
SOILS
REMEDIAL ACTION