Engineering Commons^™

An In Situ Cell For Characterization Of Solids By Soft X-Ray Absorption, Ian J. Drake, Teris C. N. Liu, Mary Gilles, Tolek Tyliszczak, A. L. D. Kilcoyne, David K. Shuh, Richard A. Mathies, Alexis T. Bell

US Department of Energy Publications

A cell has been designed and fabricated for in situ characterization of catalysts and environmental materials using soft x-ray absorption spectroscopy and spectromicroscopy at photon energies above 250 eV. “Lab-on-a-chip” technologies were used to fabricate the cell on a glass wafer. The sample compartment is 1.0 mm in diameter and has a gas path length of 0.8 mm to minimize x-ray absorption in the gas phase. The sample compartment can be heated to 533 K by an Al resistive heater and gas flows up to 5.0 cm³ min⁻¹ can be supplied to the sample compartment through microchannels. The …

Dissolution Of Uranyl Microprecipitates In Subsurface Sediments At Hanford Site, Usa, Chongxuan Liu, John M. Zachara, Odeta Qafoku, James Mckinley, Steve M. Heald, Zheming Wang

US Department of Energy Publications

The dissolution of uranium was investigated from contaminated sediments obtained at the US. Department of Energy (U.S. DOE) Hanford site. The uranium existed in the sediments as uranyl silicate microprecipitates in fractures, cleavages, and cavities within sediment grains. Uranium dissolution was studied in Na, Na-Ca, and NH₄ electrolytes with pH ranging from 7.0 to 9.5 under ambient CO₂ pressure. The rate and extent of uranium dissolution was influenced by uranyl mineral solubility, carbonate concentration, and mass transfer rate from intraparticle regions. Dissolved uranium concentration reached constant values within a month in electrolytes below pH 8.2, whereas concentrations continued …

Copper Sorption Mechanisms On Smectites, Daniel G. Strawn, Noel E. Palmer, Luca J. Furnare, Carmen Goodell, James E. Amonette, Ravi K. Kukkadapu

US Department of Energy Publications

Due to the importance of clay minerals in metal sorption, many studies have attempted to derive mechanistic models that describe adsorption processes. These models often include several different types of adsorption sites, including permanent charge sites and silanol and aluminol functional groups on the edges of clay minerals. To provide a basis for development of adsorption models it is critical that molecular-level studies be done to characterize sorption processes. In this study we conducted X-ray absorption fine structure (XAFS) and electron paramagnetic resonance (EPR) spectroscopic experiments on copper (II) sorbed on smectite clays using suspension pH and ionic strength as …

Biogeochemical Transformation Of Fe Minerals In A Petroleum-Contaminated Aquifer, John M. Zachara, Ravi K. Kukkadapu, Paul L. Gassman, Alice Dohnalkova, Jim K. Fredrickson, Todd Anderson

US Department of Energy Publications

The Bemidji aquifer in Minnesota, USA is a well-studied site of subsurface petroleum contamination. The site contains an anoxic groundwater plume where soluble petroleum constituents serve as an energy source for a region of methanogenesis near the source and bacterial Fe(III) reduction further down gradient. Methanogenesis apparently begins when bioavailable Fe(III) is exhausted within the sediment. Past studies indicate that Geobacter species and Geothrix fermentens–like organisms are the primary dissimilatory Fe-reducing bacteria at this site. The Fe mineralogy of the pristine aquifer sediments and samples from the methanogenic (source) and Fe(III) reducing zones were characterized in this study to …

Reduction Of Tco4- By Sediment-Associated Biogenic Fe(Ii), James K. Fredrickson, John M. Zachara, David W. Kennedy, Ravi K. Kukkadapu, James P. Mckinley, Steve M. Heald, Chongxuan Liu, Andrew E. Plymale

US Department of Energy Publications

The potential for reduction of ⁹⁹TcO₄^-_(aq) to poorly soluble ⁹⁹TcO₂ · nH₂O_(s) by biogenic sediment-associated Fe(II) was investigated with three Fe(III)-oxide containing subsurface materials and the dissimilatory metal-reducing subsurface bacterium Shewanella putrefaciens CN32. Two of the subsurface materials from the U.S. Department of Energy’s Hanford and Oak Ridge sites contained significant amounts of Mn(III,IV) oxides and net bioreduction of Fe(III) to Fe(II) was not observed until essentially all of the hydroxylamine HCl-extractable Mn was reduced. In anoxic, unreduced sediment or where Mn oxide bioreduction was incomplete, exogenous biogenic TcO_{2 …}

Biotransformation Of Two-Line Silica-Ferrihydrite By A Dissimilatory Fe(Iii)-Reducing Bacterium: Formation Of Carbonate Green Rust In The Presence Of Phosphate, Ravi K. Kukkadapu, John M. Zachara, James K. Fredrickson, David W. Kennedy

US Department of Energy Publications

The reductive biotransformation of two Si-ferrihydrite coprecipitates (1 and 5 mole % Si) by Shewanella putrefaciens, strain CN32, was investigated in 1,4-piperazinediethanesulfonic acid-buffered media (pH ~7) with lactate as the electron donor. Anthraquinone-2,6-disulfonate, an electron shuttle, was present in the media. Experiments were performed without and with PO₄^3- (P) (1 to 20 mmol/L) in media containing 50 mmol/L Fe. Our objectives were to define the combined effects of SiO₄^{4 -} (Si) and P on the bioreducibility and biomineralization of ferrihydrites under anoxic conditions. Iron reduction was measured as a function of time, solids were characterized …

Synthesis Of Colloidal Mn2+:Zno Quantum Dots And High-Tc Ferromagnetic Nanocrystalline Thin Films, Nick S. Norberg, Kevin R. Kittilstved, James E. Amonette, Ravi K. Kukkadapu, Dana A. Schwartz, Daniel R. Gamelin

US Department of Energy Publications

We report the synthesis of colloidal Mn²⁺-doped ZnO (Mn²⁺:ZnO) quantum dots and the preparation of room-temperature ferromagnetic nanocrystalline thin films. Mn²⁺:ZnO nanocrystals were prepared by a hydrolysis and condensation reaction in DMSO under atmospheric conditions. Synthesis was monitored by electronic absorption and electron paramagnetic resonance (EPR) spectroscopies. Zn(OAc)₂ was found to strongly inhibit oxidation of Mn²⁺ by O₂, allowing the synthesis of Mn2+:ZnO to be performed aerobically. Mn2+ ions were removed from the surfaces of as-prepared nanocrystals using dodecylamine to yield high-quality internally doped Mn2+:ZnO colloids of nearly spherical shape …

Geomicrobiology Of High-Level Nuclear Waste-Contaminated Vadose Sediments At The Hanford Site, Washington State, James K. Fredrickson, John M. Zachara, David L. Balkwill, David Kennedy, Shu-Mei W. Li, Heather M. Kostandarithes, Michael J. Daly, Margaret F. Romine, Fred J. Brockman

US Department of Energy Publications

Sediments from a high-level nuclear waste plume were collected as part of investigations to evaluate the potential fate and migration of contaminants in the subsurface. The plume originated from a leak that occurred in 1962 from a waste tank consisting of high concentrations of alkali, nitrate, aluminate, Cr(VI), ¹³⁷Cs, and ⁹⁹Tc. Investigations were initiated to determine the distribution of viable microorganisms in the vadose sediment samples, probe the phylogeny of cultivated and uncultivated members, and evaluate the ability of the cultivated organisms to survive acute doses of ionizing radiation. The populations of viable aerobic heterotrophic bacteria were generally …

Assessing Conceptual Models For Subsurface Reactive Transport Of Inorganic Contaminants, J.A. Davis, S.B. Yabusaki, C.I. Steefel, John M. Zachara, G.P. Curtis, G.D. Redden, L.J. Criscenti, B.D. Honeyman

US Department of Energy Publications

In many subsurface situations where human health and environmental quality are at risk (e.g., contaminant hydrogeology, petroleum extraction, carbon sequestration, etc.), scientists and engineers are being asked by federal agency decision-makers to predict the fate of chemical species under conditions where both reactions and transport are processes of first-order importance.

In 2002, a working group (WG) was formed by representatives of the U.S. Geological Survey, Environmental Protection Agency,Department of Energy,Nuclear Regulatory Commission, Department of Agriculture,and Army Engineer Research and Development Center to assess the role of reactive transport modeling (RTM) in addressing these situations. Specifically, the goals of the WG …

Cryogenic Laser Induced Fluorescence Characterization Of U(Vi) In Hanford Vadose Zone Pore Waters, Zheming Wang, John M. Zachara, Wassana Yantasee, Paul Gassman, Chongxuan Liu, Alan Joly

US Department of Energy Publications

Ambient and liquid helium temperature laser-induced time-resolved uranyl fluorescence spectroscopy was applied to study the speciation of aqueous uranyl solutions containing carbonate and phosphate and two porewater samples obtained by ultracentrifugation of U(VI)-contaminated sediments. The significantly enhanced fluorescence signal intensity and spectral resolution found at liquid helium temperature allowed, for the first time, direct fluorescence spectroscopic observation of the higher aqueous uranyl complexes with carbonate: UO₂(CO₃)₂ ^2-, UO₂(CO₃)₃ ^4-, and (UO₂)₂(OH)₃CO₃ ^-. The porewater samples were non-fluorescent at room temperature. …

Microscale Distribution Of Cesium Sorbed To Biotite And Muscovite, James Mckinley, John M. Zachara, Steven Heald, Alice Dohnalkova, Matthew Newville, Steve Sutton

US Department of Energy Publications

Individual 1-3 mm biotite and muscovite clasts from Hanford sediment were contacted with 0.08 M CsNO₃. They were examined using electron or X-ray microprobe methods, as intact specimens or sectioned perpendicular to their basal planes. Cs+ was observed to preferentially sorb to mica edges, steps on mica surfaces, or fractured regions. The localization of Cs conformed to hypothesized strong binding to frayed edge sites in preference to sites on basal planes. In section, Cs⁺ was found to penetrate the mica interior, forming discrete zones of concentration, particularly in muscovite. In biotite, Cs was more abundant, permeating the …

Spectroscopic And Diffraction Study Of Uranium Speciation In Contaminated Vadose Zone Sediments From The Hanford Site, Washington State, Jeffrey Catalano, Steven Heald, John M. Zachara, Gordon Brown Jr.

US Department of Energy Publications

Contamination of vadose zone sediments under tank BX-102 at the Hanford site, Washington, resulted from the accidental release of 7-8 metric tons of uranium dissolved in caustic aqueous sludge in 1951. We have applied synchrotron-based X-ray spectroscopic and diffraction techniques to characterize the speciation of uranium in samples of these contaminated sediments. U L_III-edge X-ray absorption fine structure (XAFS) spectroscopic studies demonstrate that uranium occurs predominantly as a uranium- (VI) silicate from the uranophane group of minerals. XAFS cannot distinguish between the members of this mineral group due to the near identical local coordination environments of uranium in …

Biogeochemical Transformation Of Fe Minerals In A Petroleum-Contaminated Aquifer, John M. Zachara, Ravi K. Kukkadapu, Paul Gassman, Alice Dohnalkova, James K. Fredrickson, Todd Anderson

US Department of Energy Publications

The Bemidji aquifer in Minnesota, USA is a well-studied site of subsurface petroleum contamination. The site contains an anoxic groundwater plume where soluble petroleum constituents serve as an energy source for a region of methanogenesis near the source and bacterial Fe(III) reduction further down gradient. Methanogenesis apparently begins when bioavailable Fe(III) is exhausted within the sediment. Past studies indicate that Geobacter species and Geothrix fermentens–like organisms are the primary dissimilatory Fe-reducing bacteria at this site. The Fe mineralogy of the pristine aquifer sediments and samples from the methanogenic (source) and Fe(III) reducing zones were characterized in this study to …

Chromium Speciation And Mobility In A High Level Nuclear Waste Vadose Zone Plume, John M. Zachara, Calvin Ainsworth, Gordon Brown Jr., Jeffery Catalano, James Mckinley, Odeta Qafoku, Steven Smith, James Szecsody, Sam Traina, Jeffrey Warner

US Department of Energy Publications

Radioactive core samples containing elevated concentrations of Cr from a high level nuclear waste plume in the Hanford vadose zone were studied to assess the future mobility of Cr. Cr(VI) is an important subsurface contaminant at the Hanford Site. The plume originated in 1969 by leakage of self-boiling supernate from a tank containing REDOX process waste. The supernate contained high concentrations of alkali (NaOH ≈ 5.25 mol/L), salt (NaNO₃/NaNO₂ >10 mol/L), aluminate [Al(OH)₄ ⁻ = 3.36 mol/L], Cr(VI) (0.413 mol/L), and ¹³⁷Cs⁺(6.51 X 10^-5 mol/L). Water and acid extraction of the oxidized …

A Cation Exchange Model To Describe Cs+ Sorption At High Ionic Strength In Subsurface Sediments At Hanford Site, Usa, Chongxuan Liu, John M. Zachara, Steven Smith

US Department of Energy Publications

A theoretical and experimental study of cation exchange in high ionic strength electrolytes was performed using pristine subsurface sediments from the U.S. Department of Energy Hanford site. These sediments are representative of the site contaminated sediments impacted by release of high level waste (HLW) solutions containing ¹³⁷Cs⁺ in NaNO₃ brine. The binary exchange behavior of Cs⁺–Na⁺, Cs⁺–K⁺, and Na⁺–K⁺ was measured over a range in electrolyte concentration. Vanselow selectivity coefficients (K_v) that were calculated from the experimental data using Pitzer model ion activity …

Scintillator Detectors For Scanning Transmission X-Ray Microscopes At The Advanced Light Source, S. Fakra, A. L. D. Kilcoyne, Tolek Tyliszczak

US Department of Energy Publications

The choice of x-ray detectors presents a challenge for scanning transmission x-ray microscopes (STXM). The ultimate detector for the ALS STXMs should have a very high efficiency over a wide energy range, single photon counting capabilities up to 1GHz, high rejection of red laser light, fast response, and work in both vacuum and at atmospheric pressure. The results of an investigation using a photomultiplier tube (PMT) with a number of different scintillators are presented. The PMT is used in photon counting and analog modes. Scintillators used for this study include commercially available phosphor powders and various single crystals.

Unique Electron Polarimeter Analyzing Power Comparison And Precision Spin-Based Energy Measurement, J. Grames, C. K. Sinclair, J. Mitchell, E. Chudakov, H. Fenker, A. Freyberger, D.W. Higinbotham, M. Poelker, M. Steigerwald, M. Tiefenback, C. Cavata, S. Escoffier, F. Marie, T. Pussieux, P. Vernin, S. Danagoulian, V. Dharmawardane, R. Fatemi, K. Joo, M. Zeier, V. Gorbenko, R. Nasseripour, B. Raue, R. Suleiman, B. Zihlmann

US Department of Energy Publications

Precision measurements of the relative analyzing powers of five electron beam polarimeters, based on Compton, Møller, and Mott scattering, have been performed using the CEBAF accelerator at the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory). A Wien filter in the 100 keV beam line of the injector was used to vary the electron spin orientation exiting the injector. High statistical precision measurements of the scattering asymmetry as a function of the spin orientation were made with each polarimeter. Since each polarimeter receives beam with the same magnitude of polarization, these asymmetry measurements permit a high statistical precision comparison of the …

Spin- And Angle-Resolved Spectroscopy Of S 2P Photoionization In The Hydrogen Sulfide Molecule, G. Turri, G. Snell, B. Langer, M. Martins, E. Kukk, S. E. Canton, R. C. Bilodeau, N. Cherepkov, John D. Bozek, A. L. D. Kilcoyne, N. Berrah

US Department of Energy Publications

Angle- and spin-resolved photoelectron spectroscopy with circularly and linearly polarized synchrotron radiation were used to study the electronic structure of the hydrogen sulfide molecule. A strong effect of the molecular environment appears in the spin-resolved measurements and, although less clearly, in the angular distribution of the sulfur 2 p photoelectrons. The anisotropy and spin parameters of the three main spectral components have been obtained. The validity of simple atomic models in explaining the results is discussed.

Methodology For Estimating Removable Quantities Of Agricultural Residues For Bioenergy And Bioproduct Use, Richard Nelson, Marie Walsh, John Sheehan, Robin Graham

US Department of Energy Publications

A methodology was developed to estimate quantities of crop residues that can be removed while maintaining rain or wind erosion at less than or equal to the tolerable soil-loss level. Six corn and wheat rotations in the 10 largest corn-producing states were analyzed. Residue removal rates for each rotation were evaluated for conventional, mulch/reduced, and no-till field operations. The analyses indicated that potential removable maximum quantities range from nearly 5.5 million dry metric t/yr for a continuous corn rotation using conventional till in Kansas to more than 97 million dry metric t/yr for a corn-wheat rotation using no-till in Illinois.

Carbon 1s Photoelectron Spectroscopy Of Halomethanes. Effects Of Electronegativity, Hardness, Charge Distribution, And Relaxation, T. Darrah Thomas, Leif J. Saethre, Knut J. Børve, John D. Bozek, Marko Huttula, Edwin Kukk

US Department of Energy Publications

Carbon 1s ionization energies have been measured for 12 halomethanes. These together with earlier measurements provide 27 compounds for investigating the relationship between core-ionization energies and the electronegativity and hardness of the halogens. The ionization energies correlate nearly linearly with the sum of the electronegativities of the halogens attached to the central carbon. Both electronegativity and hardness play important roles in determining the ionization energy, and it is found that the linear relationship between ionization energy and electronegativity arises from an interplay of the electronegativity and hardness of the halogens and the length and ionicity of the carbon-halogen bond.

In Situ Characterization Of Aluminum-Containing Mineral-Microorganism Aqueous Suspensions Using Scanning Transmission X-Ray Microscopy, Tae Hyun Yoon, Stephen B. Johnson, Karim Benzerara, Colin S. Doyle, Tolek Tyliszczak, David K. Shuh, Gordon E. Brown, Jr.

US Department of Energy Publications

In situ characterization of colloidal particles under hydrous conditions is one of the key requirements for understanding their state of aggregation and impact on the transport of pollutants in aqueous environments. Scanning transmission X-ray microscopy (STXM) is one of the few techniques that can satisfy this need by providing element- and chemical-state-specific 2-D maps at a spatial resolution better than 50nmusing soft X-rays from synchrotron radiation wiggler or undulator sources tuned to the absorption edges of different elements. X-ray absorption near-edge structure (XANES) spectra can also be collected simultaneously at a similar spatial resolution and can provide phase identification in …