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Outer Sphere Adsorption of Pb(II)EDTA on Goethite

Description: FTIR and EXAFS spectroscopic measurements were performed on Pb(II)EDTA adsorbed on goethite as functions of pH (4-6), Pb(II)EDTA concentration (0.11 {micro}M - 72 {micro}M), and ionic strength (16 {micro}M - 0.5M). FTIR measurements show no evidence for carboxylate-Fe(III) bonding or protonation of EDTA at Pb:EDTA = 1:1. Both FTIR and EXAFS measurements suggest that EDTA acts as a hexadentate ligand, with all four of its carboxylate and both amine groups bonded to Pb(II). No evidence was observ… more
Date: July 16, 1999
Creator: Bargar, John R
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Experiments on sorption hysteresis of desiccant materials

Description: Solid desiccant cooling systems take advantage of solar energy for air conditioning. The process involves passing air through a desiccant bed for drying and subsequent evaporative cooling to provide the air conditioning. The desiccant is then regenerated with hot air provided by a gas burner or solar collectors. This performance is limited by the capacity of the desiccant, its sorption properties, and the long-term stability of the desiccant material under cyclic operation conditions. Therefore… more
Date: August 1, 1984
Creator: Pesaran, A. & Zangrando, F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Modeling the reversible sink effect in response to transient contaminant sources

Description: A physically based diffusion model is used to evaluate the sink effect of diffusion-controlled indoor materials and to predict the transient contaminant concentration in indoor air in response to several time-varying contaminant sources. For simplicity, it is assumed the predominant indoor material is a homogeneous slab, initially free of contaminant, and the air within the room is well mixed. The model enables transient volatile organic compound (VOC) concentrations to be predicted based on th… more
Date: February 1, 2001
Creator: Zhao, Dongye; Little, John C. & Hodgson, Alfred T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Zinc surface complexes on birnessite: A density functional theory study

Description: Biogeochemical cycling of zinc is strongly influenced by sorption on birnessite minerals (layer-type MnO2), which are found in diverse terrestrial and aquatic environments. Zinc has been observed to form both tetrahedral (Zn{sup IV}) and octahedral (Zn{sup VI}) triple-corner-sharing surface complexes (TCS) at Mn(IV) vacancy sites in hexagonal birnessite. The octahedral complex is expected to be similar to that of Zn in the Mn oxide mineral, chalcophanite (ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub… more
Date: January 5, 2009
Creator: Kwon, Kideok D.; Refson, Keith & Sposito, Garrison
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Sorption Behavior and Morphology of Plutonium in the Presence of Goethite at 25 and 80C

Description: In this study, we examined the sorption behavior of Pu at elevated temperatures in the presence of one relevant mineral, goethite ({alpha}-FeOOH), over a range of concentrations that span solubility-controlled to adsorption-controlled concentrations. We focused on the sorptive behavior of two common forms of Pu: aqueous Pu(IV) and intrinsic Pu(IV) nano-colloids at 25 and 80 C in a dilute pH 8 NaCl/NaHCO{sub 3} solution. The morphology of Pu sorbed to goethite was characterized using transmissio… more
Date: June 11, 2012
Creator: Zavarin, M.; Zhao, P.; Dai, Z.; Carroll, S. A. & Kersting, A. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Laboratory And Lysimeter Experimentation And Transport Modeling Of Neptunium And Strontium In Savannah River Site Sediments

Description: The Savannah River Site (SRS) conducts performance assessment (PA) calculations to determine the appropriate amount of low-level radiological waste that can be safely disposed on site. Parameters are included in these calculations that account for the interaction between the immobile solid phase and the mobile aqueous phase. These parameters are either the distribution coefficient (K{sub d} value) or the apparent solubility value (K{sub sp}). These parameters are readily found in the literature… more
Date: September 24, 2012
Creator: Kaplan, Daniel I.; Powell, B. A. & Miller, Todd J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Characterization of U9VI) Sorption-Desorption Processes and Model Upscaling

Description: Long-term sequestration of uranium at sites within the DOE complex is a significant problem that requires molecular-level information on the speciation, phase association, and spatial distribution of uranium
Date: May 24, 2007
Creator: Jr., Gordon Borwn; Catalano, Jeffrey; Singer, David & Zachara, John
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Characterization of U(VI) Sorption-Desorption Processes and Model Upscaling

Description: The objectives of the overall collaborative EMSP effort (with which this project is associated) are to characterize sorption and desorption processes of U(VI) on pristine and contaminated Hanford sediments over a range of sediment facies and materials properties. The research is intended to provide new insights on the mechanisms of U(VI) retardation at Hanford, and to develop approaches by which laboratory-characterized geochemical models can be upscaled for defensible predictions of uranium tr… more
Date: June 1, 2003
Creator: Zachara, John M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Characterization of U(VI) Sorption-Desorption Processes and Model Upscaling: Annual Report for Johns Hopkins University (Contract No. DE-FG07-02ER63498)

Description: The objectives of the overall collaborative EMSP effort (with which this project is associated) are to characterize sorption and desorption processes of U(VI) on pristine and contaminated Hanford sediments over a range of sediment facies and materials properties. The research is intended to provide new insights on the mechanisms of U(VI) retardation at Hanford, and to develop approaches by which laboratory-characterized geochemical models can be upscaled for defensible predictions of uranium tr… more
Date: June 12, 2003
Creator: Ball, William P.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A simple extension of two-phase characteristic curves to include the dry region

Description: Two-phase characteristic curves are necessary for the simulation of water and vapor flow in porous media. Existing functions such as van Genuchten, Brooks and Corey, and Luckner et al. have significant limitations in the dry region as the liquid saturation goes to zero. This region, which is important in a number of applications including liquid and vapor flow and vapor-solid sorption, has been the subject of a number of previous investigations. Most previous studies extended standard capillary… more
Date: January 25, 2000
Creator: WEBB,STEPHEN W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Chemometric Classification of Unknown Vapors by Conversion of Sensor Array Pattern Vectors to Vapor Descriptors: Extension from Mass-Transducing Sensors To Volume-Transducing Sensors

Description: A new chemometric method was recently described for classifying unknowns by transforming the vector containing the responses from a multivariate detector to a vector containing descriptors of the detected analyte (Grate et al. 1999). This approach was derived for sensor arrays where each sensor's signal is proportional to the amount of vapor sorbed by a polymer on the sensor surface. In this case, the response is proportional to the partition coefficient, K, and the concentration of the vapor i… more
Date: June 28, 2001
Creator: Grate, Jay W
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Design of the linear non-evaporable getter pump for the PEP-II B factory

Description: There are several regions in the PEP-II B Factory at SLAC that require distributed pumping to deal with large photo-desorbed gas loads or to produce very low pressures (< 10{sup -9} Torr). These regions include the Low Energy Ring Wiggler dump chambers, the transitions between the High Energy Ring arcs and straight sections, and most importantly the Interaction Region. They have designed a compact Non-Evaporable Getter pump using commercial getters that combines high pumping speed and high s… more
Date: July 21, 1997
Creator: Bertolini, L., LLNL
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Insight from simulations of single-well injection-withdrawal tracer tests on simple and complex fractures

Description: The single-well injection withdrawal (SWIW) test, a tracer test utilizing only one well, is proposed as a useful contribution to site characterization of fractured rock, as well as providing parameters relevant to tracer diffusion and sorption. The usual conceptual model of flow and solute transport through fractured rock with low matrix permeability involves solute advection and dispersion through a fracture network coupled with diffusion and sorption into the surrounding rock matrix. Unlike t… more
Date: August 6, 2009
Creator: Tsang, C.-F. & Doughty, C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Microporous Metal Organic Materials for Hydrogen Storage

Description: We have examined a number of Metal Organic Framework Materials for their potential in hydrogen storage applications. Results obtained in this study may, in general, be summarized as follows: (1) We have identified a new family of porous metal organic framework materials with the compositions M (bdc) (ted){sub 0.5}, {l_brace}M = Zn or Co, bdc = biphenyl dicarboxylate and ted = triethylene diamine{r_brace} that adsorb large quantities of hydrogen ({approx}4.6 wt%) at 77 K and a hydrogen pressure … more
Date: November 30, 2008
Creator: Sankar, S. G.; Li, Jing & Johnson, Karl
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Plutonium(VI) sorption to manganese dioxide.

Description: Redox-active metal oxides may strongly affect the environmental behavior and mobility of actinides . Manganese oxides are relatively common redox-active soil components, which have a high surface area and which some studies show sorb plutonium selectively over other mineral phases .' For plutonium, oxidation states that could exist in the environment include +111 to +VI, with Pu(IV) being predominant in the insoluble phase. Plutonium(V), and to a lesser extent Pu(VI), are the stable Pu oxidatio… more
Date: January 1, 2003
Creator: Reilly, S. D. (Sean D.); Myers, W. K. (William K.); Stout, S. A. (Stephen A.); Smith, D. M. (Donna M.); Ginder-Vogel, M. A. (Matthew A.) & Neu, M. P. (Mary P.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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DEVELOPMENT AND CHARACTERIZATION OF NOVEL COMPLEX HYDRIDESSYNTHESIZED VIA MOLTEN STATE PROCESSING

Description: This study developed novel hydrides for hydrogen storage through a novel synthesis technique utilizing high hydrogen overpressure at elevated temperatures denoted as Molten State Processing, MSP. The ultimate goal is to produce materials that have high hydrogen capacity, are stable after cycling and possess favorable thermodynamic and kinetic characteristics compatible with onboard hydrogen storage for automotive applications. In order to achieve these goals the MSP Process was developed and us… more
Date: January 9, 2006
Creator: Zidan, R
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Phase Equilibria Modification by Electric Fields

Description: This project has been focused on equilibrium and transport properties of gas-liquid, liquid-liquid, and solid-liquid systems under electric fields. The objective was to intensify separations methods that are used or can be used to process liquid waste or contaminated groundwater within DOE sites. Examples of processes that have been investigated are distillation (gas-liquid), extraction (liquid-liquid), and sorption (solid-liquid). Effects of electric fields on phase equilibria and interfacial … more
Date: December 31, 2000
Creator: Tsouris, Costas
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Multi-Regional Reactive Transport Due to Strong Anisotropy in Unsaturated Soils with Evolving Scales of Heterogeneity

Description: Current conceptualizations of state-dependent anisotropy have failed to describe field observations, and the importance of multi-region flow in strongly anisotropic soils appears to be unrecognized. It is hypothesized that under the typical conditions of arid waste sites, when strong heterogeneity is predicted, the first order small anisotropy analysis is not rigorously applicable, and non-equilibrium mass transfer governs transport. Inter-region mass transfer is dominated by local velocity var… more
Date: June 1, 2003
Creator: Moo-Young, Horace K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Analysis of three sets of SWIW tracer-test data using a two-population complex fracture model for matrix diffusion and sorption

Description: A complex fracture model employing two populations for diffusion and sorption is proposed to analyze three representative single-well injection-withdrawal (SWIW) tracer tests from Forsmark and Laxemar, the two sites under investigation by the Swedish Nuclear Fuel and Waste Management Company (SKB). One population represents the semi-infinite rock matrix and the other represents finite blocks that can become saturated, thereafter accepting no further diffusion or sorption. The diffusion and sorp… more
Date: August 1, 2009
Creator: Doughty, C. & Tsang, C. F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Importance of mineralogical data for groundwater quality affectedby CO2 leakage

Description: Recently, geological storage of CO{sub 2} has been extensively investigated. The impact of leakage from CO{sub 2} storage reservoirs on groundwater quality is one of the concerns. Dissolution of CO{sub 2} in groundwater results in a decrease in pH. Such acidic condition can affect the dissolution and sorption mechanisms of many minerals (Jaffe and Wang, 2004). Some heavy-metal-bearing minerals dissolve under acidic conditions. For example, galena (PbS) can dissolve and increase significantly Pb… more
Date: February 13, 2006
Creator: Xu, Tianfu
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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An Analytical Model for Solute Transport in Unsaturated Flowthrough a Single Fracture and Porous Rock Matrix

Description: Exact analytical solutions are presented for solute transport in an unsaturated fracture and porous rock matrix. The problem includes advective transport in the fracture and rock matrix as well as advective and diffusive fracture-matrix exchange. Linear sorption in the fracture and matrix and radioactive decay are also treated. The solution is for steady, uniform transport velocities within the fracture and matrix, but allows for independent specification of each of the velocities. The problem … more
Date: September 16, 2004
Creator: Houseworth, J.E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Mechanisms of nickel sorption by a bacteriogenic birnessite

Description: A synergistic experimental-computational approach was used to study the molecular-scale mechanisms of Ni sorption at varying loadings and at pH 6-8 on the biogenic hexagonal birnessite produced by Pseudomonas putida GB-1. We found that Ni is scavenged effectively by bacterial biomass-birnessite assemblages. At surface excess values below 0.18 mol Ni kg{sup -1} sorbent (0.13 mol Ni mol{sup -1} Mn), the biomass component of the sorbent did not interfere with Ni sorption on mineral sites. Extended… more
Date: April 1, 2010
Creator: Pena, Jasquelin; Kwon, Kideok D.; Refson, Keith; Bargar, John R. & Sposito, Garrison
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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