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Efficient Route to Highly Water-Soluble Aromatic Cyclic Hydroxamic Acid Ligands

Description: 2-Hydroxyisoquinolin-1-one (1,2-HOIQO) is a new member of the important class of aromatic cyclic hydroxamic acid ligands which are widely used in metal sequestering applications and metal chelating therapy. The first general approach for the introduction of substituents at the aromatic ring of the chelating moiety is presented. As a useful derivative, the highly water-soluble sulfonic acid has been synthesized by an efficient route that allows general access to 1,2-HOQIO 3-carboxlic acid amides, which are the most relevant for applications.
Date: February 6, 2008
Creator: Seitz, Michael & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department

Role of dopant counter-anion functionality in polyaniline salts/blends and implications to morphology

Description: Polyanilines are of particular current interest primarily due to their relative ease of synthesis, low cost and stable conductivity in air. The insulating, polyaniline emeraldine base (PANI-EB) form becomes electrically conducting by preferential protonation or doping the imine nitrogen sites to yield an electrically conducting polyaniline emeraldine salt (PANI-ES). In this paper, wide and small angle X-ray scattering techniques (i.e., WAXS and SAXS) and light microscopy are used to characterize the influence of the dopant`s structure on the morphology of both polyaniline salt and blend. In an attempt to modify the morphology of the PANI-ES, the authors have evaluated a number of doping acids (i.e., methane sulfonic acid (HMSA), butane sulfonic acid (HBSA), dodecyl benzene sulfonic acid (HDBSA) and camphor sulfonic acid (HCSA)) that vary in size and polarity to better understanding the role of the acid in PANI-ES`s morphology and the resulting electrical conductivity. The other goal was to investigate the effect of the counter-anion structure on the nature of the phase separated PANI-ES network. The shape of the PANI-ES network in the host polycaprolactam has important implications on the nature of conduction behavior and the final electrical conductivity of the blend.
Date: April 1, 1997
Creator: Hopkins, A.R.; Rasmussen, P.G.; Basheer, R.A.; Annis, B.K. & Wignall, G.D.
Partner: UNT Libraries Government Documents Department

Material Corrion/Degradation Database

Description: The corrosion of a variety of structural metals and materials is presented. Data on specific material--and for well-studied agents--has been abstracted from the corrosion literature. In addition, limited data on one superacid (so-called ''Magic Acid,'' a mixture of 100% fluorosulfonic acid, HSO{sub 3}F, with 25% (w/w) of antimony pentafluoride (SbF{sub 5}) added) is tabulated.
Date: July 8, 1999
Creator: Kinkead, S.A.
Partner: UNT Libraries Government Documents Department

Copoly(arylene ether)s containing pendant sulfonic acid groups as proton exchange membranes

Description: A copoly(arylene ether) (PAE) with high fluorine content and a copoly(arylene ether nitrile) (PAEN) with high nitrile content, each containing pendant phenyl sulfonic acids were synthesized. The PAE and P AEN were prepared from decafluorobiphenyl (DFBP) and difluorobenzonitrile (DFBN) respectively, by polycondensation with 2phenylhydroquinone (PHQ) by conventional aromatic nucleophilic substitution reactions. sulfonic acid groups were introduced by mild post-sulfonation exclusively on the para-position of the pendant phenyl ring in PHQ. The membrane properties of the resulting sulfonated copolymers sPAE and sPAEN were compared for fuel cell applications. The copolymers sPAE and sPAEN, each having a degree of sulfonation (OS) of 1.0 had high ion exchange capacities (IEC{sub v})(wet) (volume-based, wet state) of 1.77 and 2.55 meq./cm3, high proton conductivities of 135.4 and 140.1 mS/cm at 80 C, and acceptable volume-based water uptake of 44.5 -51.9 vol% at 80 C, respectively, compared to Nafion. The data points of these copolymer membranes are located in the upper left-hand corner in the trade-off plot of alternative hydrocarbon polyelectrolyte membranes (PEM) for the relationship between proton conductivity versus water uptake (weight based or volume based), i.e., high proton conductivity and low water uptake. Furthermore, the relative selectivity derived from proton conductivity and methanol permeability is higher than that of Nafion.
Date: January 1, 2009
Creator: Dae Sik, Kim; Yu Seung, Kim; Gilles, Robertson & Guiver, Michael D
Partner: UNT Libraries Government Documents Department


Description: The proof of concept of SO2 electrolysis for the hybrid sulfur (HyS) process is the second priority research target of the DOE Nuclear Hydrogen Initiative's thermochemical program for FY07. The proof of concept of the liquid-phase option must be demonstrated at the single cell level for an extended run times (>100 hours). The rate of development of HyS will depend on the identification of a promising membrane or an alternative means for controlling sulfur formation. Once successful long-duration operation has been demonstrated, SRNL will develop a multi-cell stack that can be connected to the H2SO4 decomposer being developed by SNL for the S-I ILS for a Hybrid Sulfur Integrated Laboratory-Scale Experiment during FY 2008. During the first quarter of FY07, SRNL continued the component development and membrane development activities with the goal of identifying and characterizing improved electrodes, electrocatalysts, membranes and MEA configurations which could then be tested at larger scale in the SDE test facility. A modified glass cell was fabricated to allow measurements of sulfur dioxide (SO2) transport across membrane samples at elevated temperatures (up to 70 C). This testing also includes evaluating SO2 transport in different sulfuric acid concentrations (30-70 wt%). A new potentiostat/frequency analyzer was installed for determining ionic conductivity of membranes. This instrument enhances our capabilities to characterize membrane, electrocatalyst and MEA properties and performance. Continuing work from FY06, evaluations were preformed on various commercial and experimental membranes and electrocatalyst materials for the SDE. Several different types of commercially-available membranes were analyzed for sulfur dioxide transport as a function of acid strength including perfluorinated sulfonic acid (PFSA), sulfonated polyetherketone-ketone, and poly-benzimidazole (PBI) membranes. Experimental membranes from the sulfonated diels-alder polyphenylenes (SDAPP) and modified Nafion{reg_sign} 117 were evaluated for SO{sub 2} transport as well. These membranes exhibited reduced transport coefficient for SO{sub 2} transport without the ...
Date: December 20, 2006
Creator: Summers, W
Partner: UNT Libraries Government Documents Department


Description: The technique for adjusting the valence of Pu in the Pu(IV-VI) system to the Pa(IV) state for efficient solvent extraction or anion exchange is described. Investigations show that Pu(VI) may be reliably reduced to Pu(IV) with ferrous suifamate s. Nitric acid concentration must be between 2 and 6 M to avoid Pu disproportionation of suifamate precipitation. Ferrous sulfamate concentration is kept below 1 M to prevent crystal formation after the reaction, but Pu concentration may be as high as 250 g/l. (P.C.H.)
Date: February 1, 1961
Creator: Campbell, M.H.
Partner: UNT Libraries Government Documents Department

Direct methanol fuel cell performance using sulfonated poly (arylene ether sulfone) random copolymers as electrolytes.

Description: Sulfonated poly(arylene ether sulfone) random copolymers are a new series of sulfonic acid containing polymers that have shown promise as fuel cell electrolytes. Here, we report on direct methanol fuel cell (DMFC) performance of this class of polymers at sulfonation levels ranging from 40 to 60% (monomer basis). The DMFC performance of these polymers is compared to that of Nafion 117, the long standing standard in fuel cell testing. These polymers show a higher selectivity for protons over methanol for all the sulfonation levels tested, with the 40% sulfonated polymer showing 2.5 times the selectivity of Nafion. While the higher sulfonated forms (50 and 60%) did show a higher selectivity, only the lower sulfonation levels (40 and 45%) have shown improved performance in DMFC testing. The results of these experiments will be discussed in terms of the relevant test conditions, and experimentally determined membrane properties. The relevant DMFC properties of these polymers will be discussed in terms of sulfonation level and compared to those of Nafion 117.
Date: January 1, 2001
Creator: Zawodzinski, T. A. (Thomas A.), Jr.; Zelenay, P. (Piotr); Hickner, M. (Michael); Wang, F. (Feng); McGrath, James E. & Pivovar, B. S. (Bryan Scott)
Partner: UNT Libraries Government Documents Department

Final Report - Phase II - Biogeochemistry of Uranium Under Reducing and Re-oxidizing Conditions: An Integrated Laboratory and Field Study

Description: Our understanding of subsurface microbiology is hindered by the inaccessibility of this environment, particularly when the hydrogeologic medium is contaminated with toxic substances. Past research in our labs indicated that the composition of the growth medium (e.g., bicarbonate complexation of U(VI)) and the underlying mineral phase (e.g., hematite) significantly affects the rate and extent of U(VI) reduction and immobilization through a variety of effects. Our research was aimed at elucidating those effects to a much greater extent, while exploring the potential for U(IV) reoxidation and subsequent re-mobilization, which also appears to depend on the mineral phases present in the system. The project reported on here was an extension ($20,575) of the prior (much larger) project. This report is focused only on the work completed during the extension period. Further information on the larger impacts of our research, including 28 publications, can be found in the final report for the following projects: 1) Biogeochemistry of Uranium Under Reducing and Re-oxidizing Conditions: An Integrated Laboratory and Field Study Grant # DE-FG03-01ER63270, and 2) Acceptable Endpoints for Metals and Radionuclides: Quantifying the Stability of Uranium and Lead Immobilized Under Sulfate Reducing Conditions Grant # DE-FG03-98ER62630/A001 In this Phase II project, the toxic effects of uranium(VI) were studied using Desulfovibrio desulfuricans G20 in a medium containing bicarbonate or 1, 4-piperazinediethane sulfonic acid disodium salt monohydrate (PIPES) buffer (each at 30 mM, pH 7). The toxicity of uranium(VI) was dependent on the medium buffer and was observed in terms of longer lag times and in some cases, no measurable growth. The minimum inhibiting concentration (MIC) was 140 M U(VI) in PIPES buffered medium. This is 36 times lower than previously reported for D. desulfuricans. These results suggest that U(VI) toxicity and the detoxification mechanisms of G20 depend greatly on the chemical forms of U(VI) present ...
Date: September 28, 2006
Creator: Peyton, Brent & Sani, Rajesh
Partner: UNT Libraries Government Documents Department


Description: The reaction velocity constant for the oxidation of Pu(III) by nitrite in HNO/sub 3/ solution containing ferrous sulfanate is given. The reaction rate was found to be measurable by means of spectrophotometry. The data indicate the reaction to be a pseudo first-order reaction in the region of HNO/sub 3/ and nitrite concentration of interest. The reaction velocity constant, expressed as a first-order reaction with respect to Pu, was found for several values of HNO/ sub 3/ and nitrite concentrations. The HNC/sub 3/ reaction velocity constant relationship is given. The oxidation of the ferrous sulfamate--Pu(III Pu(III) solution proceeds successively through the sulfamate, ferrous, and Pu(III) ions. An autocatalytic mechanism is asscciated with the oxidation of both ferrous and Pu ions which obviates the possibility of simple calculations of constants based on nitrite concentration. An empirical relationship between the reaction velociiy constant and the (added) nitrite concentration is given. (auth)
Date: July 17, 1957
Creator: Brunstad, A.
Partner: UNT Libraries Government Documents Department


Description: Practical procedures were demonstrated for partitioning plutonium from uranium in the Purex process with hydrazine-stabilized uranium(IV) nitrate as the reducing reagent for plutonium. Typical partitioning results were 0.04--0.2% loss of plutonium to the uranium product and less than 1 wt% uranium in the plutonium product. With uranium(IV) nitrate as a replacement for ferrous sulfamate, most solids in wastes from the Parex process can be eliminated. No undue hazard is expected from the use of hydrazine as the stabilizing agent. (auth)
Date: April 1, 1963
Creator: Schlea, C.S.; Caverly, M.R.; Henry, H.E. & Jenkins, W.J.
Partner: UNT Libraries Government Documents Department

Spectrophotometric Determination of Cerium With Tiron

Description: A spectrophotometric method for the determination of cerium and Tiron (disodium-1,2-dihydroxybenzene-3,5disulfonate) was applied to the determination of cerium in samples which contain uranium and zirconium. The ceriumTiron complex in solutions of pH 8 or greater exhibits an absorption maximum of 500 m mu . This reagent does not react with any other lanthanive element. The interference of iron, uranium, and zirconium was eliminated by extracting these interfering elements with a solution of trioctylphosphine oxide in cyclohexane. (auth)
Date: June 14, 1957
Creator: McDowell, B. L.; Meyer, A. S., Jr. & White, J. C.
Partner: UNT Libraries Government Documents Department

Concentration of Plutonium by Cation Exchange--Stabilization of Pu(III) in Nitric Acid

Description: A study to define the effectiveness limits of sulfamic acid and to discover other better stabilizers for Pu(III) is described. Ascorbic and isoascorbic acids, used in conjunction with sulfamic acid reduced Pu(IV) to stable Pu(III) in nitric acid. Aminoguanidine sulfate also retarded the oxidation of Pu(III) but did not reduce Pu(IV). (J.R.D.)
Date: February 1, 1959
Creator: Tober, F. W. & Russel, E. R.
Partner: UNT Libraries Government Documents Department

Molecular modeling of the pendant chain in Nafion{reg_sign}

Description: Ion transport through perfluorosulfonic acid ionomers such as Nafion{reg_sign} is controlled by both the microstructure of the polymer and the charge and water distribution in the hydrated polymer. The authors present here the results of theoretical calculations on the side chain of Nafion{reg_sign}, establishing microscopic information for the modeling of water modeling of water modeling of water and proton transport in the membrane. Optimized geometries for the trifluoromethane sulfonic acid fragment (CF{sub 3}SO{sub 3}H), the di-trifluoromethane ether fragment (CF{sub 3}OCF{sub 3}), and the side chain (CF{sub 3}{single_bond}OCF{sub 2}CF(CF{sub 3})OCF{sub 2}CF{sub 2}SO{sub 3}H) were determined by means of both ab initio Hartree Fock theory with second order Moeller-Plesset electron correlation corrections, and density functional theory with Becke`s three parameter hybrid method. Several rotational potential energy surfaces were calculated to assess chain flexibility and proton accessibility. A probe water molecule was added to each of the fragments to characterize hydrophilic sites. These calculations confirmed that the sulfonic acid group is hydrophilic and the ethers are hydrophobic. Molecular dynamics simulations were then performed on the side chain to check the conditions required to stretch the pendant chain. Thermal averages of several structural parameters assessing the flexibility and stretch of the chain were computed from selected conformations produced in the simulation and these results indicate that although the sulfonate group is free to rotate, the chain stretches little. The construction of a potential energy surface for rotation about the second ether group suggests that the side chain exists in a folded or curled up conformation. A physical continuum dielectric solvent model was used to obtain free energies of electrostatic interaction of the fragments and the full chain with the solvent.
Date: March 1, 1998
Creator: Paddison, S.J. & Zawodzinski, T.A.
Partner: UNT Libraries Government Documents Department

Evaluation of the humidification requirements of new proton exchange membranes for fuel cells

Description: Measurements of PEM fuel cell device performance were made with different gas inlet temperatures and relative humidity using a newly-designed test fixture. Significant improvement in device performance was observed when the fuel inlet temperature was increased above the operating temperature of the cell. These measurements were then correlated to a model to describe energy and mass transport processes. Proton exchange membrane (PEM), fuel cells--the focus of this study--use an ion conducting polymer, especially polyperfluorosulfonic acid materials. These polymer materials, when imbibed with water, exhibit solution-like properties, but because the anions are chemically bound to the polymeric structure, the electrolyte is contained. Importantly, product water removal is simplified, as electrolyte dilution is not a concern. However, the proton transport rate is a function of the polymer geometry, which is set, in part, by the polymer water content. Consequently, dynamics of water flow are essential to understand the design of efficient conversion devices.
Date: May 1, 1995
Creator: Grot, S.A.; Hedstrom, J.C. & Vanderborgh, N.E.
Partner: UNT Libraries Government Documents Department

Management of Spent Organic Ion-Exchange Resins by Photochemical Oxidation

Description: Management of spent ion-exchange resin waste arising from nuclear reactor operations by traditional practice of encapsulation in cement is associated with problems such as swelling and disintegration. Complete oxidation (mineralization) is an attractive alternative option. This paper reports the development of photochemical mineralization process for organic ion-exchange resins of poly (styrene-divinyl benzene) type with sulfonic acid and quaternary ammonium functional groups. It is a two-step process consisting of dissolution (conversion of solid resin into water-soluble reaction products) and photo-Fenton mineralization of the dissolved resin. Cation and anion resin dissolution was effected by reaction of the resin with H2O2 at 50-60 C in the presence of ferrous/copper sulphate catalyst. Direct dissolution of mixed resin was not efficient. However, the cation resin portion in the mixed resin could be selectively dissolved without affecting the anion portion. The solid anion resin after separation from the cation resin solution could be dissolved. About 0.5 liters of 50% H2O2 was required for dissolution of one kg of wet resin. The reaction time was 4-5 hours. Dissolution experiments were conducted on up to 8 liters of wet resin. The second step, viz., photo-Fenton mineralization of the dissolved resin was effected at ambient temperature(25-35 C). Kinetic results of laboratory scale experiments in immersion type photo-reactor and pilot scale experiments in tubular flow photo-reactor were presented. These results clearly demonstrated the photo-Fenton mineralization of dissolved resin at ambient temperature with stoichiometric quantity of H2O2 as against 70-200% excess H2O2 requirement in chemical mineralization experiments under Fenton oxidation conditions at 90-95 C. Based on these studies, a treatment scheme was developed and presented in this paper.
Date: February 26, 2003
Creator: Srinivas, C.; Sugilal, S. & Wattal, P. K.
Partner: UNT Libraries Government Documents Department


Description: Methods were developed for the syntheses of alkalimetal p--bar ethylbenzenesulfonates. P--bar ethylbenzenesulfonic acid is isolated and is purified as barium p--bar -ethylbenzenesulfonate which is converted to the Na, K, or Cs p-bar -ethylbenzenesulfonate by means of a slight excess of the corresponding alkali-metal carbonate. Lithium sulfate is used to form the lithium p-bar -ethylbenzenesulfonate. (auth)
Date: March 30, 1962
Creator: White, J.C. & Holsopple, H.L.
Partner: UNT Libraries Government Documents Department


Description: Thermochemical processes are being developed to provide global-scale quantities of hydrogen. A variant on sulfur-based thermochemical cycles is the Hybrid Sulfur (HyS) Process which uses a sulfur dioxide depolarized electrolyzer (SDE) to produce the hydrogen. In FY05, testing at the Savannah River National Laboratory (SRNL) explored a low temperature fuel cell design concept for the SDE. The advantages of this design concept include high electrochemical efficiency and small volumetric footprint that is crucial for successful implementation on a commercial scale. A key component of the SDE is the ion conductive membrane through which protons produced at anode migrate to the cathode and react to produce hydrogen. An ideal membrane for the SDE should have both low ionic resistivity and low sulfur dioxide transport. These features allow the electrolyzer to perform at high currents with low potentials, along with preventing contamination of both the hydrogen output and poisoning of the catalysts involved. Another key component is the electrocatalyst material used for the anode and cathode. Good electrocatalysts should be chemically stable and low overpotential for the desired electrochemical reactions. This report summarizes results from activities to evaluate different membrane and electrocatalyst materials for the SDE. Several different types of commercially-available membranes were analyzed for ionic resistance and sulfur dioxide transport including perfluorinated sulfonic acid, sulfonated poly-etherketone-ketone, and poly-benzimidazole membranes. Of these membrane types, the poly-benzimidazole (PBI) membrane, Celtec-L, exhibited the best combination of characteristics for use in an SDE. Testing examined the activity and stability of platinum and palladium as electrocatalyst for the SDE in sulfuric acid solutions. Cyclic and linear sweep voltammetry revealed that platinum provided better catalytic activity with much lower potentials and higher currents than palladium. Testing also showed that the catalyst activity is strongly influenced by concentration of the sulfuric acid. Various cell configurations were examined with ...
Date: August 3, 2006
Creator: Colon-Mercado, H; David Hobbs, D; Daryl Coleman, D & Amy Ekechukwu, A
Partner: UNT Libraries Government Documents Department