Characterization of U(VI) Sorption-Desoprtion Processes and Model Upscaling

Ball, William P.

John Hopkins University, Baltimore, MD

关键词: Sediments;    37 Inorganic, Organic, Physical And Analytical Chemistry;    Molecular Structure;    Soils;    Valence;   

DOI  :  10.2172/885259
RP-ID  :  EMSP-86748--2005
RP-ID  :  FG07-02ER63498
RP-ID  :  885259

美国|英语

来源: UNT Digital Library

【 摘 要 】

In order to apply predictive reactive transport models to the Hanford site, detailed knowledge of the speciation of contaminants is required. Important speciation parameters include: (1) oxidation state; (2) the local molecular structure surrounding contaminant elements; (3) the type and binding of a contaminant ion sorption complex (if adsorbed); (4) the type(s) of phase within which a contaminant is structurally incorporated [e.g., present in a three-dimensional precipitate(s)]; (5) the phase associations of a contaminant; (6) the microscopic distribution of a contaminant within sediments and soils. In the present study, we have used synchrotron-based X-ray spectroscopic methods to study the speciation of U and Cu in contaminated soil and sediment samples from the Hanford Site. To complement and complete our initial XAFS investigation of U speciation in contaminated vadose zone sediments below tank BX-102, we have also performed mXRD studies of two sediment sample to identify the specific U(VI)-silicate phase present. Samples from the 300 Area were examined by mSXRF to determine the microscopic distribution and element associations of Cu and U. These samples were also analyzed by U LIII- and Cu K-edge XAFS spectroscopy to determine the chemical speciation of these elements.