HR: 1340h
AN: V23A-1247    [Abstracts]
TI: Selenate and Selenite Reduction by Nanometer-Scale Zerovalent Iron Particles
AU: * Olegario, J T
EM: jovilynn@sfsu.edu
AF: San Francisco State University, Department of Chemistry and Biochemistry, 1600 Holloway Ave., San Francisco, CA 94132, United States
AU: Yee, N Y
EM: nay@sfsu.edu
AF: San Francisco State University, Department of Chemistry and Biochemistry, 1600 Holloway Ave., San Francisco, CA 94132, United States
AU: Manning, B A
EM: bmanning@sfsu.edu
AF: San Francisco State University, Department of Chemistry and Biochemistry, 1600 Holloway Ave., San Francisco, CA 94132, United States
AB: Selenium oxyanions can be present in agricultural drainage waters, coal mining effluent, and as fission products in radioactive wastes. The objective of this work was to evaluate the effectiveness of both nanometer scale zerovalent iron (nano-Fe) and 100 mesh Fe filings for reduction and immobilization of aqueous selenate Se(VI) and selenite Se(IV). The uptake of Se(VI) and Se(IV) using batch equilibrium, kinetics, and X-ray absorption spectroscopic (XAS) techniques was investigated. In addition, a thorough investigation of the solid phase corrosion products by X-ray diffraction was conducted. The crystalline corrosion product was similar to magnetite, though some distinct differences in the XRD results were noted between Se(IV)- and Se(VI)-treated samples. Application of quantitative X-ray absorption near edge spectroscopy (XANES) revealed that both Se(VI) and Se(IV) were reduced to a mixture of elemental Se(0) plus iron(II) selenide (Se(-II)). The Se local atomic structure in Se(VI)- and Se(IV)-treated nano-Fe was determined using extended x-ray absorption fine structure spectroscopy (EXAFS) and a Se-Se interatomic distance of 2.44 angstroms was revealed. This work suggests that nano-Fe is an efficient material for removing dissolved Se(VI) and Se(IV) from waste waters by formation of an insoluble, reduced FeSe product.
DE: 0461 Metals
DE: 0471 Oxidation/reduction reactions (4851)
DE: 0478 Pollution: urban, regional and global (0345, 4251)
DE: 1065 Major and trace element geochemistry
DE: 1806 Chemistry of fresh water
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting