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Full-Text Articles in Engineering
Kinetic Analysis Of The Bacterial Reduction Of Goethite, Chongxuan Liu, John M. Zachara, James K. Fredrickson, Cynthia Brinkman
Kinetic Analysis Of The Bacterial Reduction Of Goethite, Chongxuan Liu, John M. Zachara, James K. Fredrickson, Cynthia Brinkman
US Department of Energy Publications
The kinetics of dissimilatory reduction of goethite (RFeOOH) was studied in batch cultures of a groundwater bacterium, Shewanella putrefaciens, strain CN32 in pH 7 bicarbonate buffer. The rate and extent of goethite reduction were measured as a function of electron acceptor (goethite) and donor (lactate) concentrations. Increasing goethite concentrations increased both the rate and extent of Fe(III) reduction when cell and lactate concentrations were held constant. However, constant initial reduction rates were observed after normalization to the Fe(II) sorption capacity of FeOOH, suggesting that the bacterial reduction rate was first order with respect to surface site concentration. Increasing …
Biotransformation Of Ni-Substituted Hydrous Ferric Oxide By An Fe(Iii)-Reducing Bacterium, James K. Fredrickson, John M. Zachara, Ravi K. Kukkadapu, Yuri A. Gorby, Steven C. Smith, Christopher F. Brown
Biotransformation Of Ni-Substituted Hydrous Ferric Oxide By An Fe(Iii)-Reducing Bacterium, James K. Fredrickson, John M. Zachara, Ravi K. Kukkadapu, Yuri A. Gorby, Steven C. Smith, Christopher F. Brown
US Department of Energy Publications
The reductive biotransformation of a Ni2+-substituted (5 mol %) hydrous ferric oxide (NiHFO) by Shewanella putrefaciens, strain CN32, was investigated under anoxic conditions at circumneutral pH. Our objectives were to define the influence of Ni2+ substitution on the bioreducibility of the HFO and the biomineralization products formed and to identify biogeochemical factors controlling the phase distribution of Ni2+ during bioreduction. Incubations with CN32 and NiHFO were sampled after 14 and 32 d, and both aqueous chemistry and solid phases were characterized. By comparison of these results with a previous study (Fredrickson, J. K.; Zachara, J. M.; …
Dissimilatory Bacterial Reduction Of Al-Substituted Goethite In Subsurface Sediments, Ravi K. Kukkadapu, John M. Zachara, Steven C. Smith, James K. Fredrickson, Chongxuan Liu
Dissimilatory Bacterial Reduction Of Al-Substituted Goethite In Subsurface Sediments, Ravi K. Kukkadapu, John M. Zachara, Steven C. Smith, James K. Fredrickson, Chongxuan Liu
US Department of Energy Publications
The microbiologic reduction of a 0.2 to 2.0 µm size fraction of an Atlantic coastal plain sediment (Eatontown) was investigated using a dissimilatory Fe(III)-reducing bacterium (Shewanella putrefaciens, strain CN32) to evaluate mineralogic controls on the rate and extent of Fe(III) reduction and the resulting distribution of biogenic Fe(II). Mössbauer spectroscopy and X-ray diffraction (XRD) were used to show that the sedimentary Fe (III) oxide was Al-substituted goethite (13–17% Al) that existed as 1- to 5-µm aggregates of indistinct morphology. Bioreduction experiments were performed in two buffers [HCO3‑; 1,4-piperazinediethansulfonic acid (PIPES)] both without and with 2,6-anthraquinone …
Kinetics And Mechanism Of Birnessite Reduction By Catechol, Christopher J. Matocha, Donald L. Sparks, James E. Amonette, Ravi K. Kukkadapu
Kinetics And Mechanism Of Birnessite Reduction By Catechol, Christopher J. Matocha, Donald L. Sparks, James E. Amonette, Ravi K. Kukkadapu
US Department of Energy Publications
The complex interactions of oxidizable organic ligands with soil Mn(III,IV) (hydr)oxide minerals have received little study by in situspectroscopic techniques.We used a combination of an in situ electron paramagnetic resonance stopped-flow (EPR-SF) spectroscopic technique and stirred-batch studies to measure the reductive dissolution kinetics of birnessite (δ-MnO2), a common Mn mineral in soils, by catechol (1,2-dihydroxybenzene). The reaction was rapid, independent of pH, and essentially complete within seconds under conditions of excess catechol at pH 4 to 6. The overall empirical second-order rate equation describing the reductive dissolution rate was d[Mn(II)]/dt = k[CAT]1.0[SA]1.0 where …
Distribution And Retention Of 137cs In Sediments At The Hanford Site, Washington, James Mckinley, Cynthia Zeissler, John M. Zachara, R. Jeffrey Serne, Richard Lindstrom, Herbert Schaef, Robert Orr
Distribution And Retention Of 137cs In Sediments At The Hanford Site, Washington, James Mckinley, Cynthia Zeissler, John M. Zachara, R. Jeffrey Serne, Richard Lindstrom, Herbert Schaef, Robert Orr
US Department of Energy Publications
137Cesium and other contaminants have leaked from single-shell storage tanks (SSTs) into coarse-textured, relatively unweathered unconsolidated sediments. Contaminated sediments were retrieved from beneath a leaky SST to investigate the distribution of adsorbed 137Cs+ across different sediment size fractions. All fractions contained mica (biotite, muscovite, vermiculatized biotite), quartz, and plagioclase along with smectite and kaolinite in the clay-size fraction. A phosphor-plate autoradiograph method was used to identify particular sediment particles responsible for retaining 137Cs+. The Cs-bearing particles were found to be individual mica flakes or agglomerated smectite, mica, quartz, and plagioclase. Of these, only the …
Microbial Reduction Of Fe(Iii) And Sorption/Precipitation Of Fe(Ii) On Shewanella Putrefaciens Strain Cn32, Chongxuan Liu, John M. Zachara, Yuri Gorby, Jim Szecsody, Christopher Brown
Microbial Reduction Of Fe(Iii) And Sorption/Precipitation Of Fe(Ii) On Shewanella Putrefaciens Strain Cn32, Chongxuan Liu, John M. Zachara, Yuri Gorby, Jim Szecsody, Christopher Brown
US Department of Energy Publications
The influence of Fe(II) on the dissimilatory bacterial reduction of an Fe(III) aqueous complex (Fe(III)-citrateaq) was investigated using Shewanella putrefaciens strain CN32. The sorption of Fe(II) on CN32 followed a Langmuir isotherm. Least-squares fitting gave a maximum sorption capacity of Qmax = 4.19 x 10-3 mol/1012 cells (1.19 mmol/ m2 of cell surface area) and an affinity coefficient of log K = 3.29. The growth yield of CN32 with respect to Fe(III)aq reduction showed a linear trend with an average value of 5.24 (±0.12) x 109 cells/mmol of Fe(III). The reduction of …
Uncertainties Of Monod Kinetic Parameters Nonlinearly Estimated From Batch Experiments, Chongxuan Liu, John M. Zachara
Uncertainties Of Monod Kinetic Parameters Nonlinearly Estimated From Batch Experiments, Chongxuan Liu, John M. Zachara
US Department of Energy Publications
Monod kinetic parameters (Ks, µmax, and Y) that are estimated from batch experimental data can have large uncertainties due to linear correlations between them. The degree of correlation and the resulting uncertainties of the Monod parameters are functions of the initial experimental conditions, the values of the parameters, the type and magnitude of measurement errors, and the sampling number. Careful manipulation of experimental conditions can reduce the correlations between Monod parameters allowing for the estimation of Monod kinetic parameters with the lowest degree of uncertainty. By dimensionless analysis, the correlation and relative standard deviations of Monod parameters …
Solubilization Of Fe(Iii) Oxide-Bound Trace Metals By A Dissimilatory Fe(Iii) Reducing Bacterium, John M. Zachara, James K. Fredrickson, Steven Smith, Paul Gassman
Solubilization Of Fe(Iii) Oxide-Bound Trace Metals By A Dissimilatory Fe(Iii) Reducing Bacterium, John M. Zachara, James K. Fredrickson, Steven Smith, Paul Gassman
US Department of Energy Publications
Trace metals associate with Fe(III) oxides as adsorbed or coprecipitated species, and consequently, the biogeochemical cycles of iron and the trace metals are closely linked. This communication investigated the solubilization of coprecipitated Co(III) and Ni(II) from goethite (α-FeOOH) during dissimilatory bacterial iron reduction to provide insights on biogeochemical factors controlling trace-element fluxes in anoxic environments. Suspensions of homogeneously substituted Co-FeOOH (50 mmol/L as Co0.01Fe0.99OOH; 57Co-labeled) in eight different buffer/media solutions were inoculated with a facultative, metal-reducing bacteria isolated from groundwater (Shewanella putrefacians CN32), and incubated under strictly anaerobic conditions for periods up to 32 …
Uranium(Vi) Sorption Complexes On Montmorillonite As A Function Of Solution Chemistry, Catherine J. Chisholm-Brause, John M. Berg, Robert A. Matzner, David E. Morris
Uranium(Vi) Sorption Complexes On Montmorillonite As A Function Of Solution Chemistry, Catherine J. Chisholm-Brause, John M. Berg, Robert A. Matzner, David E. Morris
US Department of Energy Publications
We have investigated the effect of changes in solution chemistry on the nature of uranyl sorption complexes on montmorillonite (SAz-1) at different surface coverages (1.43–53.6 µmol/g). Uranyl uptake onto SAz-1 between pH 3 and 7 was determined in both titration and batch-mode experiments. These pH values result in solutions that contain a range of monomeric and oligomeric aqueous uranyl species. Continuous-wave and timeresolved emission spectroscopies were used to investigate the nature of U(VI) sorbed to SAz-1. A discrete set of uranyl surface complexes has been identified over a wide range of pH values at these low to moderate coverages. For …
Vibrational Structure And Vibronic Coupling In The Carbon 1s Photoelectron Spectra Of Ethane And Deuteroethane, Tor Karlson, Leif J. Sæthre, Knut J. Børve, Nora Berrah, Edwin Kukk, John D. Bozek, Thomas X. Carroll, T. Darrah Thomas
Vibrational Structure And Vibronic Coupling In The Carbon 1s Photoelectron Spectra Of Ethane And Deuteroethane, Tor Karlson, Leif J. Sæthre, Knut J. Børve, Nora Berrah, Edwin Kukk, John D. Bozek, Thomas X. Carroll, T. Darrah Thomas
US Department of Energy Publications
The carbon 1s photoelectron spectrum of ethane, C2H6, has been measured at a photon energy of 329 eV and an instrumental resolution of 70 meV. The spectrum shows a rich vibrational structure which is resolved using least-squares fits to the data. Only C-H stretching and CCH bending modes contribute significantly to the spectrum. The lack of excitation of the C-C stretching mode is explained in terms of changes in hybridization at the spectator carbon. To investigate the possibility of incomplete localization of the core hole, the spectra of C2H6 and C2D …
Chemical Insights From High-Resolution X-Ray Photoelectron Spectroscopy And Ab Initio Theory: Propyne, Trifluoropropyne, And Ethynylsulfur Pentafluoride, Leif J. Sæthre, Nora Berrah, John D. Bozek, Knut J. Borve, Thomas X. Carroll, Edwin Kukk, Gary L. Gard, Rolf Winter, T. Darrah Thomas
Chemical Insights From High-Resolution X-Ray Photoelectron Spectroscopy And Ab Initio Theory: Propyne, Trifluoropropyne, And Ethynylsulfur Pentafluoride, Leif J. Sæthre, Nora Berrah, John D. Bozek, Knut J. Borve, Thomas X. Carroll, Edwin Kukk, Gary L. Gard, Rolf Winter, T. Darrah Thomas
US Department of Energy Publications
High-resolution carbon 1s photoelectron spectroscopy of propyne (HC=CH3) shows a spectrum in which the contributions from the three chemically inequivalent carbons are clearly resolved and marked by distinct vibrational structure. This structure is well accounted for by ab initio theory. For 3,3,3-trifluoropropyne (HC=CF3) and ethynylsulfur pentafluoride (HC=SF5), the ethynyl carbons show only a broad structure and have energies that differ only slightly from one another. The core-ionization energies can be qualitatively understood in terms of conventional resonance structures; the vibrational broadening for the fluorinated compounds can be understood in terms of the effects of …