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Oxidation

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Articles 151 - 180 of 207

Full-Text Articles in Engineering

Elevated Temperature Oxidation Of Boron Modified Ti-6al-4v, Deborah May-Katherine Sweeney Jan 2008

Elevated Temperature Oxidation Of Boron Modified Ti-6al-4v, Deborah May-Katherine Sweeney

Browse all Theses and Dissertations

The addition of trace amounts (~0.1 wt%) of boron to titanium alloys refines theas-cast grain size by an order of magnitude from 2000μm to 200μm. The reduced grain size has potentially beneficial effects on the processibility of titanium alloys. Reports also indicate that the room temperature corrosion resistance of the boron containing alloys may be substantially greater than conventional titanium alloys. In this study, the effects of boron addition on oxidation resistance are investigated, since conventional titanium alloys have limited corrosion resistance in air above 650°C. The mass gain per unit surface area was measured during elevated temperatures exposed to …

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A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Marcos A. Cheney, Pradip K. Bhowmik, Shizhi Qian, Sang W. Joo, Wensheng Hou, Joseph M. Okoh Jan 2008

A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Marcos A. Cheney, Pradip K. Bhowmik, Shizhi Qian, Sang W. Joo, Wensheng Hou, Joseph M. Okoh

Mechanical & Aerospace Engineering Faculty Publications

A new method for preparing black birnessite nanoparticles is introduced. The initial synthesis process resembles the classical McKenzie method of preparing brown birnessite except for slower cooling and closing the system from the ambient air. Subsequent process, including wet-aging at 7° C for 48 hours, overnight freezing, and lyophilization, is shown to convert the brown birnessite into black birnessite with complex nanomorphology with folded sheets and spirals. Characterization of the product is performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N(2) adsorption ( BET) techniques. Wet-aging and lyophilization times are …

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Kinetics And Mechanism Of Oxygen Delignification, Yun Ji May 2007

Kinetics And Mechanism Of Oxygen Delignification, Yun Ji

Electronic Theses and Dissertations

Considerable research has been conducted into the kinetics and selectivity of the oxygen delignification process to overcome limitation in its use. However most studies were performed in a batch reactor whereby the hydroxide and dissolved oxygen concentrations are changing during the reaction time in an effort to simulate tower performance in pulp mills. This makes it difficult to determine the reaction order of the different reactants in the rate expressions. Also the lignin content and cellulose degradation of the pulp are only established at the end of the experiment when the sample is removed from the batch reactor. To overcome …

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Biostimulation Of Iron Reduction And Subsequent Oxidation Of Sediment Containing Fe-Silicates And Fe-Oxides: Effect Of Redox Cycling On Fe(Iii) Bioreduction, John Komlos, Ravi K. Kukkadapu, John M. Zachara, Peter R. Jaffe Jan 2007

Biostimulation Of Iron Reduction And Subsequent Oxidation Of Sediment Containing Fe-Silicates And Fe-Oxides: Effect Of Redox Cycling On Fe(Iii) Bioreduction, John Komlos, Ravi K. Kukkadapu, John M. Zachara, Peter R. Jaffe

United States Department of Energy: Publications

Sediment containing a mixture of iron (Fe)-phases, including Fe-oxides (mostly Al-goethite) and Fe-silicates (illites and vermiculite) was bioreduced in a long-term flow through column experiment followed by re-oxidation with dissolved oxygen. The objective of this study was (a) to determine the nature of the re-oxidized Fe(III), and (b) to determine how redox cycling of Fe would affect subsequent Fe(III)-bioavailability. In addition, the effect of Mn on Fe(III) reduction was explored.57Fe-Mössbauer spectroscopy measurements showed that biostimulation resulted in partial reduction (20%) of silicate Fe(III) to silicate Fe(II) while the reduction of goethite was negligible. Furthermore, the reduction of Fe …

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Development Of Method For Synthesis Of Pt–Co Cathode Catalysts For Pem Fuel Cells, Xuguang Li, Héctor R. Colón-Mercado, Gang Wu, Jong-Won Lee, Branko N. Popov Jan 2007

Development Of Method For Synthesis Of Pt–Co Cathode Catalysts For Pem Fuel Cells, Xuguang Li, Héctor R. Colón-Mercado, Gang Wu, Jong-Won Lee, Branko N. Popov

Faculty Publications

A procedure was developed to synthesize a platinum–cobalt (Pt–Co) alloy electrocatalyst for oxygen reduction using Co/C composite as a support. The Pt–Co/C catalysts were synthesized through: (i) chemical oxidation of carbon black, (ii) Co deposition on the oxidized carbon using a chelation method, (iii) chemical treatment in an acidic medium to remove excess of Co on the carbon surface, (iv) Pt deposition onto the Co/C support, and (v) postheat treatment to form the Pt–Co alloy catalyst. The synthesized Pt–Co/C catalyst showed improved activity and long-term stability in polymer electrolyte membrane …

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Low-Temperature Synthesis Of A Ptru/Nb0.1ti0.9o2 Electrocatalyst For Methanol Oxidation, Brenda L. García, Roderick Fuentes, John W. Weidner Jan 2007

Low-Temperature Synthesis Of A Ptru/Nb0.1ti0.9o2 Electrocatalyst For Methanol Oxidation, Brenda L. García, Roderick Fuentes, John W. Weidner

Faculty Publications

Niobium was doped into anatase TiO2 support at 10 mol % (Nb0.1Ti0.9O2) using sol-gel chemistry. A PtRu/Nb0.1Ti0.9O2 catalyst was synthesized by LiBH4 reduction in tetrahydrofuran. The methanol electro-oxidation activity of the catalyst shows that this oxide support was electrically conductive. The current (A/gPt) was 6% higher on the PtRu/Nb0.1Ti0.9O2 catalyst compared to a commercial PtRu/C catalyst at 25°C. The electrochemically active surface area of the PtRu/C was 94% higher than PtRu/Nb0.1Ti0.9O2, thus the current per active site was 100% higher on PtRu/Nb0.1Ti0.9O2. A membrane electrode assembly with PtRu/Nb0.1Ti0.9O2 had 46% higher current (A/gPt) than an equivalent E-TEK membrane electrode assembly …

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A New Spectroscopic Method For The Non-Destructive Characterization Of Weathering Damage In Plastics, Andrew Robert George Nov 2006

A New Spectroscopic Method For The Non-Destructive Characterization Of Weathering Damage In Plastics, Andrew Robert George

Theses and Dissertations

The weathering of plastics and composites is a problem because of the loss of both physical and mechanical properties that it causes in these materials. But this weathering effect has been difficult, and in some cases, impossible to characterize without the destruction of the plastic or composite part. Clearly a rapid, reliable, and non-destructive test for the extent of the weathering damage is critically needed. A recent problem that arose at Superyacht Solutions, a boat repair company in Australia, required a solution to just this problem. Such a test was developed for Superyacht Solutions, and is being applied across a …

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Effects Of Frequency And Environment On Fatigue Behavior Of An Oxide-Oxide Ceramic Matrix Composite At 1200°C, Griffin Hetrick Jun 2006

Effects Of Frequency And Environment On Fatigue Behavior Of An Oxide-Oxide Ceramic Matrix Composite At 1200°C, Griffin Hetrick

Theses and Dissertations

Advances in aeronautical engineering in the 21st century depend upon materials that can perform well in extreme environments such as high temperatures and oxidizing conditions. Nextel™720/Alumina (N720/A) is an oxide/oxide ceramic matrix composite with a porous alumina matrix that has been identified as a candidate material for such applications. This research investigated the effects of frequency on fatigue response of N720/A at 1200°C in both air and steam environment. Prior investigation of this material by Eber [8] in 2005 studied fatigue behavior at 1200°C in air and in steam environments at the frequency of 1.0 Hz. The current research focused …

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Supercritical-Carbon Dioxide-Assisted Cyclic Deposition Of Metal Oxide And Metal Thin Films, Dipak Barua, Theodosia Gougousi, Erin D. Young, Gregory N. Parsons Feb 2006

Supercritical-Carbon Dioxide-Assisted Cyclic Deposition Of Metal Oxide And Metal Thin Films, Dipak Barua, Theodosia Gougousi, Erin D. Young, Gregory N. Parsons

Chemical and Biochemical Engineering Faculty Research & Creative Works

Thin films of aluminum oxide and palladium were deposited on silicon at low temperatures (70-120 °C) by a cyclic adsorption/reaction processes using supercritical CO2 solvent. Precursors included Al(hfac)3, Al(acac)3, and Pd(hfac)2, and aqueous H2O2, tert-butyl peracetate, and H2 were used as the oxidants or reductants. For the precursors studied, growth proceeds through a multilayer precursor adsorption in each deposition cycle, and film thickness increased linearly with the number of growth cycles.

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Polymer-Derived Si-Al-C-N Ceramics:Oxidation, Hot-Corrosion, And Structural Evolution, Yiguang Wang Jan 2006

Polymer-Derived Si-Al-C-N Ceramics:Oxidation, Hot-Corrosion, And Structural Evolution, Yiguang Wang

Electronic Theses and Dissertations

Polymer-derived ceramics are a new class of materials synthesized by thermal decomposition of polymer precursors. Previous studies have shown that the materials exhibit excellent thermo-mechanical properties and can be stable at temperatures up to 2000oC. Furthermore, the novel polymer-to-ceramics process enables the manipulation of the ceramic structures at the atomic/nano level by designing the chemistry of polymer precursors and controlling the pyrolysis conditions, thereby, the properties of ceramics. In this dissertation, oxidation/hot-corrosion behavior and the structural evolution of Si-Al-C-N ceramics have been studied. The structural evolution and crystallization behavior of the SiCN and SiAlCN ceramics are investigated using FT-IR, XRD, …

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A Non-Isolated Half Bridge Buck-Based Converter For Vrm Application And Small Signal Modeling Of A Non-Conventional Two Phase Bu, Majd Batarseh Jan 2006

A Non-Isolated Half Bridge Buck-Based Converter For Vrm Application And Small Signal Modeling Of A Non-Conventional Two Phase Bu, Majd Batarseh

Electronic Theses and Dissertations

This dissertation is about treatment of the nonbiodegradable organic content of landfill leachate by chemical oxidation combined with biological treatment. It is divided into three parts. In the first part, ferrate was compared to Fenton's reagent for the purpose of removing non-biodegradable organic compounds from mature leachate. Oxidation conditions (time, pH, and dose) were optimized to yield maximum organic removal using two leachate samples from 20 and 12-year old solid waste cells. Results from this research demonstrated that ferrate and Fenton's reagent had similar optimum pH ranges (3-5), but different organic removal capacities, ranging from 54 to 79 % of …

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The Effect Of Oxidation On The Structure Of Styryl-Substituted Sexithiophenes: A Resonance Raman Spectroscopy And Density Functional Theory Study, Tracy Clarke, Keith Gordon, David L. Officer, Daina K. Grant Jan 2006

The Effect Of Oxidation On The Structure Of Styryl-Substituted Sexithiophenes: A Resonance Raman Spectroscopy And Density Functional Theory Study, Tracy Clarke, Keith Gordon, David L. Officer, Daina K. Grant

Australian Institute for Innovative Materials - Papers

The structures and vibrational properties of a series of styryl-substituted sexithiophenes and their charged species have been examined using resonance Raman spectroscopy in conjunction with density functional theory calculations. The calculated geometries of the radical cations and dications indicate that the quinoidal charged defects are more strongly localized in the center of the thiophene backbone than is observed in other sexithiophenes. This defect confinement, induced by the positions of the styryl substituents, is particularly evident in the dication species. However, the defect confinement weakens when alkoxy groups are added onto the phenyl rings by causing the extension of the charged …

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Modeling And Simulation Of Silicon Photonic Crystals Effect Of Oxidation And Etching, G. M. Haider Ali Jul 2005

Modeling And Simulation Of Silicon Photonic Crystals Effect Of Oxidation And Etching, G. M. Haider Ali

Electrical & Computer Engineering Theses & Dissertations

Recent inventions of a silicon Raman laser and a high speed photon modulator might motivate integration of electronic and photonic active devices on the same silicon chip. Passive photonic devices in silicon such as waveguides, couplers and splitters have been developed. Photonic devices must be compatible with standard silicon CMOS fabrication processing in order to achieve the integration. Since CMOS fabrication involves a myriad of process steps, it is important to study the effect of processing on photonic devices. Oxidation and etching, two fundamental processes in silicon technology, are utilized in this thesis to model their effects on silicon photonic …

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An Analysis Of Microstructure And Corrosion Resistance In Underwater Friction Stir Welded 304l Stainless Steel, Tad Dee Clark Jun 2005

An Analysis Of Microstructure And Corrosion Resistance In Underwater Friction Stir Welded 304l Stainless Steel, Tad Dee Clark

Theses and Dissertations

An effective procedure and parameter window was developed for underwater friction stir welding (UWFSW) 304L stainless steel with a PCBN tool. UWFSW produced statistically significant: increases in yield strengths, decreases in percent elongation. The ultimate tensile strength was found to be significantly higher at certain parameters. Although sigma was identified in the UWFSWs, a significant reduction of sigma was found in UWFSWs compared to ambient FSWs. The degree of sensitization in UWFSWs was evaluated using double loop EPR testing and oxalic acid electro-etched metallography. Results were compared to base metal, ambient FSW, and arc welds. Upper and lower sensitization localization …

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Ethane Oxidation And Pyrolysis From 5 Bar To 1000 Bar: Experiments And Simulation, Abdul Aziz Abdul Raman Mar 2005

Ethane Oxidation And Pyrolysis From 5 Bar To 1000 Bar: Experiments And Simulation, Abdul Aziz Abdul Raman

Abdul Aziz Abdul Raman

An extensive experimental study of ethane oxidation and pyrolysis has been conducted in the high pressure shock tube at UIC covering reflected shock pressures from 5-1000 bar, reaction temperatures up to 1550 K and stoichiometric (Φ = 1 ), fuel rich (Φ = 5), and pyrolytic mixtures. The experimental data has been used to develop a single model that can simulate the whole dataset very well and is the first ethane model capable of simulating experimental results over such an extensive range of pressure, temperature, and stoichiometry. © 2005 Wiley Periodicals, Inc.

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Analysis Of Oxidation And Surface Characteristics In Hot Strip Rolling, Zhengyi Jiang, Weihua Sun, Jianning Tang, Dongbin Wei, A K. Tieu Jan 2005

Analysis Of Oxidation And Surface Characteristics In Hot Strip Rolling, Zhengyi Jiang, Weihua Sun, Jianning Tang, Dongbin Wei, A K. Tieu

Faculty of Engineering - Papers (Archive)

Deformation characteristics of the oxide scale in hot strip mill have not been quantified before and the principle of the effect of oxide scale deformation in the roll bite on strip surface roughness has not yet been revealed. In this paper, analysis of the thin secondary oxide scale formed in hot metal rolling and its surface roughness micro deformation is carried out by experiments and finite element analysis. Simulation results are compared with the measured values, which show that they are in close agreement. Surface roughness transfer during hot metal rolling is also discussed.

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Halonitromethane Treatment Using Advanced Oxidation Process: Rates, Mechanisms And Kinetic Modeling, Stuart Kirkham Cole Jan 2005

Halonitromethane Treatment Using Advanced Oxidation Process: Rates, Mechanisms And Kinetic Modeling, Stuart Kirkham Cole

Civil & Environmental Engineering Theses & Dissertations

Halonitromethanes (HNMs) are low molecular weight halogenated disinfection-by-products (DBPs) found to be formed during ozonation, chlorination, or chloramination of waters containing natural bromide ion and nitrogenous organic matter. This work identifies the absolute rate constants for the oxidative hydroxyl radical (•OH) and reductive hydrated electron e- aq extinction of HNM compounds. Three forms of HNMs included in this study are the chlorinated, brominated, and mixed halogenated compounds. Electron pulse radiolysis and transient absorption spectroscopy were used to measure •OH and e- aq radical absolute reaction rate constants for a total of nine HNMs. To elucidate the decomposition reaction …

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Purification And Structural Characterization Of Caged Dna Oligonucleotides, Brendan Michael Mcadams Jan 2005

Purification And Structural Characterization Of Caged Dna Oligonucleotides, Brendan Michael Mcadams

LSU Master's Theses

“Cage” molecules reversibly block the bioactivity of a target substrate molecule by a photolyzable covalent bond formed at a functional site of the target molecule. The attachment of cage molecules to DNA oligodeoxynucleotides (ODNs) to transiently block bioactivity, and site-specific restoration of bioactivity using targeted light exposure, would enable a new method of control for use in gene therapy, molecular/DNA computing, molecular biology, and drug delivery. The reaction of the cage molecule 1-(4,5-dimethoxy-2-nitrophenyl)diazoethane (DMNPE) with DNA ODNs in an batch reaction yields a mixture of products with varying degrees of caging. Purification and verification of the hypothesized site of DMNPE …

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Bifurcation Phenomena For An Oxidation Reaction In A Continuously Stirred Tank Reactor. Ii Diabatic Operation, Mark Nelson, Harvinder Sidhu Jan 2004

Bifurcation Phenomena For An Oxidation Reaction In A Continuously Stirred Tank Reactor. Ii Diabatic Operation, Mark Nelson, Harvinder Sidhu

Faculty of Engineering and Information Sciences - Papers: Part A

We extend an investigation into the bifurcation phenomena exhibited by an oxidation reaction in an adiabatic reactor to the case of a diabatic reactor. The primary bifurcation parameter is the fuel fraction; the inflow pressure and inflow temperature are the secondary bifurcation parameters. The inclusion of heat loss in the model does not change the static steady-state bifurcation diagram; the organising centre is a pitchfork singularity for both the adiabatic and diabatic reactors. However, unlike the adiabatic reactor, Hopf bifurcations may occur in the diabatic reactor. We construct the degenerate Hopf bifurcation curve by determining the double-Hopf locus. When the …

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Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics - Phase Three, Samir Moujaes, Yitung Chen Aug 2003

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics - Phase Three, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The proposed work will combine chemical kinetics and hydrodynamics in target and test-loop lead-bismuth eutectic (LBE) systems to model system corrosion effects. This approach will result in a predicative tool that can be validated with corrosion test data, used to systematically design tests and interpret the results, and provide guidance for optimization in LBE system designs. The task includes two subtasks. The first subtask is to try to develop the necessary predictive tools to be able to predict the levels of oxygen and corrosion products close to the boundary layer through the use of Computational Fluid Dynamics (CFD) modeling. The …

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On The Physicochemical Problems Of Aqueous Oxidation Of Polymetallic Gold Bearing Sulphide Ore In An Autoclave, Zeljko J. Kamberovic Jan 2003

On The Physicochemical Problems Of Aqueous Oxidation Of Polymetallic Gold Bearing Sulphide Ore In An Autoclave, Zeljko J. Kamberovic

Zeljko J Kamberovic

The paper presents a study on the physical and chemical changes of iron, copper and zinc sulphide minerals in process of pressure oxidation. Oxidation in autoclave is a pre-treatment unit operation for refractory sulphide ores and concentrates in order to valorisat gold, which is encapsuled mainly in pyrite matrix. Raw materials and solid residues are charasterisated. Basing on the results of chemical reactions and on shape of solids residue, we came to a conclusion concerning the mechanism of oxidation in autoclave. The results show that modelling of the process parameters of oxidation in autoclave can be used to predict efficiency …

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Response Of Ti-6al-4v And Ti-24al-11nb Alloys To Dry Sliding Wear Against Hardened Steel Jun 2002

Response Of Ti-6al-4v And Ti-24al-11nb Alloys To Dry Sliding Wear Against Hardened Steel

A.S. Md Abdul Haseeb

Titanium alloys have been of great interest in recent years because of their very attractive combination of high strength, low density and corrosion resistance. Application of these alloys in areas where wear resistance is also of importance calls for thorough investigations of their tribological properties. In this work, Ti-6Al-4V and Ti-24Al-11Nb alloys were subjected to dry sliding wear against hardened-steel counter bodies and their tribological response was investigated. A pin-on-disc type apparatus was used with a normal load of 15-45N and sliding speed of 1.88 ms -1. In the steady state, it was demonstrated that Ti-24Al-11Nb had a substantially higher …

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Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Phase Two, Samir Moujaes, Yitung Chen May 2002

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics-Phase Two, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The proposed work will combine chemical kinetics and hydrodynamics in target and test-loop lead-bismuth eutectic (LBE) systems to model system corrosion effects. This approach will result in a predicative tool that can be validated with corrosion test data, used to systematically design tests and interpret the results, and provide guidance for optimization in LBE system designs. The task includes two subtasks. The first subtask is to try to develop the necessary predictive tools to be able to predict the levels of oxygen and corrosion products close to the boundary layer through the use of Computational Fluid Dynamics (CFD) modeling. The …

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Research Of Surface-Oxidation Epitaxy Of Nio Films On Cube Textured Ni Tapes, Dongqi Shi, Mihail Ionescu, Jeff Mckinnon, Wu Ming Chen, S. X. Dou Jan 2002

Research Of Surface-Oxidation Epitaxy Of Nio Films On Cube Textured Ni Tapes, Dongqi Shi, Mihail Ionescu, Jeff Mckinnon, Wu Ming Chen, S. X. Dou

Faculty of Engineering - Papers (Archive)

Thin films of NiO were fabricated in air by surface-oxidation epitaxy (SOE) on biaxially-textured Ni substrate, for use as buffer layers for YBCO coated conductors. The surface-oxidation conditions such as the temperature and the reaction time, as well as the cooling rate, playa determining role in the process of epitaxial growth of the NiO layer. A continuous, biaxially-aligned textured NiO layer, was obtained for a 10 min oxidation in air at 1120°C,and acooling rate of 150 Klh. The roughness of the NiO layer is mostly controlled by a coarsening of some NiO grains .

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High Temperature Compression Testing Of An Advanced Carbon-Carbon Composite In An Oxidizing Atmosphere, Joshua C. Walls Jan 2002

High Temperature Compression Testing Of An Advanced Carbon-Carbon Composite In An Oxidizing Atmosphere, Joshua C. Walls

Electronic Theses and Dissertations

Compression testing of an advanced, three-dimensional weave, carbon-carbon composite was performed from room temperature to 2192°F (1200°C) in an oxidizing environment. The material tested is primarily used for missile nose cones and rocket nozzles. A test system and test method was developed for performing high temperature compression testing and techniques were developed for machining the material to minimize fiber damage and maintain accurate tolerances. Test specimens were cut from a block of the test material in the three principal fiber orientations, and off-axis tests were cut at 45" orientations to each principal fiber direction. The specimens were tested by direct …

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Development Of A Novel Co Tolerant Proton Exchange Membrane Fuel Cell Anode, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang Jan 2002

Development Of A Novel Co Tolerant Proton Exchange Membrane Fuel Cell Anode, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang

Faculty Publications

Typically Pt is alloyed with metals such as Ru, Sn, or Mo to provide a more CO-tolerant, high-performance proton exchange membrane fuel cell (PEMFC) anode. In this work, a layer of carbon-supported Ru is placed between the Pt catalyst and the anode flow field to form a filter. When oxygen is added to the fuel stream, it was predicted that the slow H2 kinetics of Ru in this filter would become an advantage compared to Pt and Pt:Ru alloy anodes, allowing a greater percentage of O2 to oxidize adsorbed CO to CO2. With an anode feed …

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Studies On Capacity Fade Of Spinel-Based Li-Ion Batteries, Ramadass Premanand, Anand Durairajan, Bala Haran, Ralph E. White, Branko N. Popov Jan 2002

Studies On Capacity Fade Of Spinel-Based Li-Ion Batteries, Ramadass Premanand, Anand Durairajan, Bala Haran, Ralph E. White, Branko N. Popov

Faculty Publications

The performance of Cell-Batt® Li-ion cells using nonstoichiometric spinel as the positive electrode material has been studied at different charging rates. The capacity of the cell was optimized based on varying the charging current and the end potential. Subsequent to this, the capacity fade of these batteries was studied at different charge currents. During cycling, cells were opened at intermittent cycles and extensive material and electrochemical characterization was done on the active material at both electrodes. For all charge currents, the resistance of both the electrodes does not vary significantly with cycling. This result is in contrast with cells …

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Electrochemical Filtering Of Co From Fuel-Cell Reformate, Balasubramanian Lakshmanan, Wayne Huang, John W. Weidner Jan 2002

Electrochemical Filtering Of Co From Fuel-Cell Reformate, Balasubramanian Lakshmanan, Wayne Huang, John W. Weidner

Faculty Publications

A proton exchange membrane fuel cell was used as a flow reactor for continuous preferential oxidation of CO over H2 from 1.0% CO in H2 under pulse-potential control. By varying the pulse profile ~e.g., on-time, off-time, pulse potential! the CO and H2 oxidation currents were varied independently. The improvement in faradaic selectivity between CO and H2 oxidation results from the promotion of CO adsorption during the off ~i.e., open-circuit! portion of the pulse. Therefore, during the on portion CO oxidation was preferred while the surface was covered with CO.

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Biotransformation Of Various Substituted Aromatic Compounds To Chiral Dihydrodihydroxy Derivatives, Henning Raschke, Michael Meier, Roland Hany, Markus D. Muller, Jan Roelof Van Der Meer, Hans-Peter E. Kohler, Joel Gerard Burken Aug 2001

Biotransformation Of Various Substituted Aromatic Compounds To Chiral Dihydrodihydroxy Derivatives, Henning Raschke, Michael Meier, Roland Hany, Markus D. Muller, Jan Roelof Van Der Meer, Hans-Peter E. Kohler, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The biotransformation of four different classes of aromatic compounds by the Escherichia coli strain DH5α(pTCB 144), which contained the chlorobenzene dioxygenase (CDO) from Pseudomonas sp. strain P51, was examined. CDO oxidized biphenyl as well as monochlorobiphenyls to the corresponding cis-2,3-dihydro-2,3-dihydroxy derivatives, whereby oxidation occurred on the unsubstituted ring. No higher substituted biphenyls were oxidized. The absolute configurations of several monosubstituted cis-benzene dihydrodiols formed by CDO were determined. All had an S configuration at the carbon atom in meta position to the substituent on the benzene nucleus. with one exception, the enantiomeric excess of several 1,4-disubstituted cis-benzene dihydrodiols formed by CDO …

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In-Situ Colloidal Mno2 Deposition And Ozonation Of 2,4-Dinitrotoluene, Kevin C. Bower, Kevin H. Gardner, Christopher M. Miller, Lingjun Kong Jul 2001

In-Situ Colloidal Mno2 Deposition And Ozonation Of 2,4-Dinitrotoluene, Kevin C. Bower, Kevin H. Gardner, Christopher M. Miller, Lingjun Kong

Civil & Environmental Engineering

Laboratory experiments are presented that demonstrate a novel in situ semipassive reactive barrier for the degradation of 2,4 dinitrotoluene created by coating aquifer surfaces by deposition of colloidal MnO2, which catalyzes ozone degradation and enhances contaminant oxidation. Ozone is added to the reactive barrier and is transported through the zone with the contaminants by existing hydraulic gradients. The communication presents the preliminary laboratory investigation demonstrating the viability of this method. Studies were conducted by coating Ottawa sand with colloidal MnO2. Results show that concentrations of MnO2 in the range of 0.2 mg/g can be deposited with no measurable change in …

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