848 Matching Results

Search Results

Advanced search parameters have been applied.

Theoretical Studies of the Behavior of Ions in Aqueous Solutions of Mixed Electrolytes With Respect to Osmionic Cell Operation

Description: From Forward: "This is the seventy-sixth of a series of reports designed to present accounts of progress in saline water conversion with the expectation that the exchange of such data will contribute to the long-range development of economical processes applicable to large-scale, low-cost demineralization of sea or other saline water."
Date: July 1963
Creator: Murphy, George W. & Matthews, Robert R.
Partner: UNT Libraries Government Documents Department

High-Temperature Transference Numbers in Pure and Mixed Aqueous Electrolytes

Description: From Abstract: "An electronic technique was used in determinations of transference numbers in aqueous electrolyte solutions by the moving-boundary method. Data for 0.1 N NaCl at temperature from 15 degrees to 125 degrees C are presented in this report. Probable causes of difficulty with the method were identified. and recommendations are made in this report for further research to overcome the difficulties."
Date: March 1964
Creator: Dismukes, Edward B.
Partner: UNT Libraries Government Documents Department

Evaluation and Consolidation of Electrolytic Thorium

Description: Abstract: "Sound, fabricable ingots of thorium were produced by triple are melting of electrolytic thorium. Consumable electrodes were fabricated by tack welding of cold-pressed and vacuum-sintered bars of the granular thorium electrodeposited from a molten-salt bath. The hydrogen content of the electrodeposited material was reduced from 80 to 4 ppm by vacuum sintering at 1250 C at pressures below 1 x 10-(-3) mm of mercury. Both sodium and chlorine content were reduced during melting; sodium from 250 to 25 ppm and chlorine from 1000 to 30 ppm. Oxygen and HCl acid-insoluble contents increased during sintering and melting. Oxygen content increased from 0.35 to 0.50 w/o and HCl acid-insoluble content from 0.8 to 4.0 w/o. A starlike includion revealed by metallographic examination of the as-cast thorium was identified as ThO2."
Date: June 15, 1955
Creator: Saller, Henry A.; Dickerson, Ronald F. & Foster, Ellis L.
Partner: UNT Libraries Government Documents Department

The Effects of Common Electrolytes on Growth and Development of Selected Species of Aquatic Actinomycetes

Description: The role that aquatic actinomycetes play, in the production of tastes and odors in water supplies has been investigated since 1948. The ability of these organisms to produce by-products in lakes and streams, which renders the water unpalatable, is of considerable public health importance. It is desirable that the waterworks industry has as much information as possible concerning the factors that contribute to the growth of these organisms. Since it appears that the aquatic actinomycetes may be isolated from most fresh-water sources, the problem of diversified environments and nutritional requirements offers an excellent field of investigation. The fresh-waters of the world contain variable quantities of electrolytes that may determine in part the biological activity of these organisms. The unsolved questions in this instance are concerned with the electrolytes present and their quantitative effects on the growth and development of these forms.
Date: August 1959
Creator: Sissom, Stanley L.
Partner: UNT Libraries

Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry

Description: The ultimate objectives of this research are to understand the principles underpinning nano-composite polymer electrolytes (CPEs) and facilitate development of novel CPEs that are low-cost, have high conductivities, large Li+ transference numbers, improved electrolyte-electrode interfacial stability, yield long cycle life, exhibit mechanical stability and are easily processable. Our approach is to use nanoparticulate silica fillers to formulate novel composite electrolytes consisting of surface-modified fumed silica nano-particles in polyethylene oxides (PEO) in the presence of lithium salts. We intend to design single-ion conducting silica nanoparticles which provide CPEs with high Li+ transference numbers. We also will develop low-Mw (molecular weight), high-Mw and crosslinked PEO electrolytes with tunable properties in terms of conductivity, transference number, interfacial stability, processability and mechanical strength
Date: January 24, 2007
Creator: Khan, Saad A.: Fedkiw Peter S. & Baker, Gregory L.
Partner: UNT Libraries Government Documents Department

Methods of Calculation of Resistance to Polarization (Corrosion Rate) Using ASTM G 59

Description: The corrosion rate of a metal (alloy) can be measured using: (1) Immersion tests or weight loss such as in ASTM G 1 and G 31 or (2) Electrochemical techniques such as in ASTM G 59. In the polarization resistance (PR) or linear polarization method (G 59), the resistance to polarization (Rp) of a metal is measured in the electrolyte of interest in the vicinity of the corrosion potential (E{sub corr}). This polarization resistance can be mathematically converted into corrosion rates (CR). A plot of E vs. I in the vicinity of E{sub corr} is generated by increasing the potential at a fixed rate of 0.1667 mV/s and measuring the output current. The polarization resistance (Rp) is defined as the slope of a potential (E) (Y axis) vs. Current (I) (X axis) plot in the vicinity of the corrosion potential (E{sub corr}). When the potential is ramped and the current is measured, E is the independent variable and I is the dependent variable. In a proper mathematical plot, E should be represented in the X axis and I in the Y axis. However, in the conventions of the corrosion community, E is always plotted in the Y axis and I in the X axis. Therefore, how this plot of Delta E/Delta I is analyzed is a matter of current debate.
Date: February 5, 2006
Creator: Wong, L L; King, K J; Martin, S I & Rebak, R B
Partner: UNT Libraries Government Documents Department

Characterization of the SEI on a carbon film electrode by combinedEQCM and spectroscopic ellipsometry

Description: The electrochemical quartz crystal microbalance (EQCM) andcyclic voltammetry have been applied simultaneously to characterizeelectron-beam deposited carbon film electrodes in LiClO4 orLiPF6-containing mixed electrolytes of ethylene carbonate (EC) anddimethyl carbonate (DMC). The structure of the carbon electrode was foundto be amorphous/disordered using Raman spectroscopy. Cyclic voltammetryin LiClO4 / EC+DMC demonstrated features typical of Liintercalation/deintercalation into/from the disordered carbon electrode,and EQCM showed a corresponding mass increase/decrease. Contrary to thecase of LiClO4 / EC+DMC electrolyte, LiPF6/EC+DMC electrolyte showed noLi deintercalation out of the thin-film carbon electrode. Combined EQCMand spectroscopic ellipsometry data were compared, and the solidelectrolyte interphase density after the first cycle in LiClO4 /EC+DMCwas estimated to be 1.3 g/cm3.
Date: January 1, 2002
Creator: Kwon, Kyungjung; Kong, Fanping; McLarnon, Frank & Evans, James W.
Partner: UNT Libraries Government Documents Department

AN INVENTORY OF PHOTOGRAPHS OF ZINC ELECTRODEPOSITED FROM ACID ELECTROLYTES

Description: Electrodeposition of zinc from acid electrolytes has been studied by several investigators in this laboratory. A large number of zinc deposits have been observed and photographs (SEM, micrographs, experimental equipment, and line drawings) have been prepared over the years 1976-1983. These photos are compiled in this LBL report to facilitate their future use by others. The tables in this report list the experimental conditions and corresponding identification numbers of photographs that are on file in the Photography Services Laboratory at the Lawrence Berkeley Laboratory. Several samples of these zinc deposits are shown.
Date: September 1, 1983
Creator: Faltemier, J. L.; Jaksic, M. M.; Tsuda, T. & Tobias, C. W.
Partner: UNT Libraries Government Documents Department

Morphological, rheological and electrochemical studies ofpoly(ethylene oxide) electrolytes containing fumed silicananoparticles

Description: In this paper, the rheology and crystallization of composite Poly(Ethylene Oxide) (PEO) electrolytes were studied by dynamic mechanical analysis, DSC and polarized light microscopy. The effects of fumed silica nanoparticles on the conductivities of the polymer electrolytes at temperatures above and below their melting point were measured and related to their rheology and crystallization behavior, respectively. The electrolyte/electrode interfacial properties and cycling performances of the composite polymer electrolytes in Li/Li cells are also discussed. The measured electrochemical properties were found to depend heavily on the operational environments and sample processing history.
Date: June 1, 2003
Creator: Xie, Jiangbing; Kerr, John B.; Duan, Robert G. & Han, Yongbong
Partner: UNT Libraries Government Documents Department

Ionic liquids for rechargeable lithium batteries

Description: We have investigated possible anticipated advantages of ionic-liquid electrolytes for use in lithium-ion batteries. Thermal stabilities and phase behavior were studied by thermal gravimetric analysis and differential scanning calorimetry. The ionic liquids studied include various imidazoliumTFSI systems, pyrrolidiniumTFSI, BMIMPF{sub 6}, BMIMBF{sub 4}, and BMIMTf. Thermal stabilities were measured for neat ionic liquids and for BMIMBF{sub 4}-LiBF{sub 4}, BMIMTf-LiTf, BMIMTFSI-LiTFSI mixtures. Conductivities have been measured for various ionic-liquid lithium-salt systems. We show the development of interfacial impedance in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell and we report results from cycling experiments for a Li|BMIMBF{sub 4} + 1 mol/kg LIBF{sub 4}|C cell. The interfacial resistance increases with time and the ionic liquid reacts with the lithium electrode. As expected, imidazolium-based ionic liquids react with lithium electrodes. We seek new ionic liquids that have better chemical stabilities.
Date: September 29, 2005
Creator: Salminen, Justin; Papaiconomou, Nicolas; Kerr, John; Prausnitz,John & Newman, John
Partner: UNT Libraries Government Documents Department

Activity Coefficient Derivatives of Ternary Systems Based on Scatchard's Neutral Electrolyte description

Description: Activity coefficient derivatives with respect to molality are presented for the Scatchard Neutral Electrolyte description of a ternary common-ion electrolyte system. These quantities are needed for the calculation of 'diffusion Onsager coefficients' and in turn for tests of the Onsager Reciprocal Relations in diffusion. The usually-omitted b{sub 23} term is included. The direct SNE binary approximations and a further approximation are discussed. Binary evaluation strategies other than constant ionic strength are considered.
Date: May 16, 2007
Creator: Miller, D G
Partner: UNT Libraries Government Documents Department

Investigating the Stability and Accuracy of the Phase Response for NOx Sensing 5% Mg-modified LaCrO3 Electrodes

Description: Impedance spectroscopy measurements were carried out on LaCr{sub 0.95}Mg{sub 0.05}O{sub 3} (LCM) asymmetric interdigitated electrodes supported on fully stabilized 8-mol% Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} (YSZ) electrolytes. Experiments were carried out using 0-50 ppm NO{sub x}, 5-15% O{sub 2} with N{sub 2} as the balance, over temperatures ranging from 600-700 C. AC measurements taken at a constant frequency between 1-100 Hz indicated the phase response of the sensor was less sensitive to fluctuations in the O{sub 2} concentration and the baseline drift was limited. Specific frequencies were observed where the sensor response was essentially temperature independent.
Date: June 14, 2007
Creator: Murray, E P; Novak, R F; Kubinski, D J; Soltis, R E; Visser, J H; Woo, L Y et al.
Partner: UNT Libraries Government Documents Department

Effect of electrode material and design on sensitivity and selectivity for high temperature impedancemetric NOx sensors

Description: Solid-state electrochemical sensors using two different sensing electrode compositions, gold and strontium-doped lanthanum manganite (LSM), were evaluated for gas phase sensing of NO{sub x} (NO and NO{sub 2}) using an impedance-metric technique. An asymmetric cell design utilizing porous YSZ electrolyte exposed both electrodes to the test gas (i.e., no reference gas). Sensitivity to less than 5 ppm NO and response/recovery times (10-90%) less than 10 s were demonstrated. Using an LSM sensing electrode, virtual identical sensitivity towards NO and NO{sub 2} was obtained, indicating that the equilibrium gas concentration was measured by the sensing electrode. In contrast, for cells employing a gold sensing electrode the NO{sub x} sensitivity varied depending on the cell design: increasing the amount of porous YSZ electrolyte on the sensor surface produced higher NO{sub 2} sensitivity compared to NO. In order to achieve comparable sensitivity for both NO and NO{sub 2}, the cell with the LSM sensing electrode required operation at a lower temperature (575 C) than the cell with the gold sensing electrode (650 C). The role of surface reactions are proposed to explain the differences in NO and NO{sub 2} selectivity using the two different electrode materials.
Date: September 23, 2009
Creator: Woo, L Y; Glass, R S; Novak, R F & Visser, J H
Partner: UNT Libraries Government Documents Department

Effect of salt identity on the phase diagram for a globularprotein in aqueous electrolyte solution

Description: Monte Carlo simulations are used to establish the potential of mean force between two globular proteins in an aqueous electrolyte solution. This potential includes nonelectrostatic contributions arising from dispersion forces first, between the globular proteins, and second, between ions in solution and between each ion and the globular protein. These latter contributions are missing from standard models. The potential of mean force, obtained from simulation, is fitted to an analytic equation. Using our analytic potential of mean force and Barker-Henderson perturbation theory, we obtain phase diagrams for lysozyme solutions that include stable and metastable fluid-fluid and solid-fluid phases when the electrolyte is 0.2 M NaSCN or NaI or NaCl. The nature of the electrolyte has a significant effect on the phase diagram.
Date: February 22, 2006
Creator: Bostrom, Mathias; Tavares, Frederico W.; Ninham, Barry W. & Prausnitz, John M.
Partner: UNT Libraries Government Documents Department

ab initio Solubility Prediction of Non-Electrolytes in Ternary Solvents Using a Combination of Jouyban-Acree and Abraham Models

Description: Article on the ab initio solubility prediction of non-electrolytes in ternary solvents using a combination of Jouyban-Acree and Abraham models.
Date: February 1, 2008
Creator: Jouyban, Abolghasem; Khoubnasabjafari, Maryam; Hamidi, Ali A. & Acree, William E. (William Eugene)
Partner: UNT College of Arts and Sciences

Bundle Binding in Polyelectrolyte Solutions

Description: Stiff polyelectrolytes are found to spontaneously form oriented bundles. Conditions under which bundling occurs are found. Molecular dynamics simulations show that divalent counterions are necessary, and the chains must be sufficiently long and stiff. No aggregation occurs for monovalent counterions. For flexible or short chains aggregation occurs, but bundle formation does not. Due to dynamical constraints the systems tend to order into a network of connected bundles, not a single bundle.
Date: January 21, 1999
Creator: Stevens, M.J.
Partner: UNT Libraries Government Documents Department

Toward a Molecular-Based Understanding of High-Temperature Solvation Phenomena in Aqueous Electrolyte Solutions

Description: The theoretical treatment of the solvation phenomenon of simple ions in aqueous solutions has been rather difficult, despite the apparent simplicity of the system. Long-range solvent-screened electrostatic interactions, coupled to the large variation (with state conditions) of the dielectric permittivity of water, give rise to a variety of rather complex solvation phenomena including dielectric saturation, electrostriction, and ion association. Notably, ion solvation in high-temperature/pressure aqueous solutions plays a leading role in hydrothermal chemistry, such as in the natural formation of ore deposits, the corrosion in boilers and reactors, and in high-temperature microbiology. Tremendous effort has been invested in the study of hydrothermal solutions to determine their thermodynamic, transport, and spectroscopic properties with the goal of elucidating the solute-solvent and solute-solute interactions over a wide range of state conditions. It is precisely at these conditions where our understanding and predictive capabilities are most precarious, in part, as a result of the coexistence of processes with two rather different length scales, i.e., short-ranged (solvation) and long-ranged (compressibility-driven) phenomena (Chialvo and Cummings 1994a). The latter feature makes hydrothermal systems extremely challenging to model, unless we are able to isolate the (compressibility-driven) propagation of the density perturbation from the (solvation-related) finite-density perturbation phenomena (Chialvo and Cummings 1995a).
Date: October 30, 1999
Creator: Chialvo, A. A.; Cummings, P. T.; Kusalik, P. G. & Simonson, J. M.
Partner: UNT Libraries Government Documents Department

Investigation of Primary Li-Si/FeS2 Cells

Description: The factors that limit the performance of thermally activated Li-Si/FeS2 batteries were defined through the use of electrochemical characterization tests and post-test examinations. For the characterization tests, 82 individual cells were instrumented with multiple voltage sensors and discharged under isothermal and isobaric conditions. The voltage data for the sensors were recorded to determine the ohmic and electrochemical impedances of each cell component at different levels of discharge. The data analysis completed to date has demonstrated that this approach can successfully differentiate the influence of various operating parameters (e.g., temperature, current density), electrode structures (e.g., FeS2 particle size), and additives on cell capacity, specific energy, and power capability. Thirty cells selected from these tests and additional tests at SNL were examined using optical and scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. These analyses documented microstructural and compositional changes in the active materials and electrolyte. In general, the electrochemical impedance of the FeS2 electrode limited cell performance. Several methods (including use of fine FeS2 particle size, graphite additions, and higher operating temperatures) produced measurable reductions in this impedance and yielded significant improvements in specific energy and power. Additions of KCl to the negative electrode extended the low-temperature capacity of this electrode by counterbalancing gradients in electrolyte composition that develop during discharge.
Date: April 1987
Creator: Redey, L.; Smaga, J. A.; Battles, J. E. & Guidotti, Ronald
Partner: UNT Libraries Government Documents Department

Negative Electrodes for Li-Ion Batteries

Description: Graphitized carbons have played a key role in the successful commercialization of Li-ion batteries. The physicochemical properties of carbon cover a wide range; therefore identifying the optimum active electrode material can be time consuming. The significant physical properties of negative electrodes for Li-ion batteries are summarized, and the relationship of these properties to their electrochemical performance in nonaqueous electrolytes, are discussed in this paper.
Date: October 1, 2001
Creator: Kinoshita, Kim & Zaghib, Karim
Partner: UNT Libraries Government Documents Department