WorldWideScience

Sample records for direct oxide reduction

  1. Direct printing and reduction of graphite oxide for flexible supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hanyung [Department of Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul (Korea, Republic of); Ve Cheah, Chang [Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Jeong, Namjo [Energy Materials and Convergence Research Department, Korea Institute of Energy Research, Daejeon (Korea, Republic of); Lee, Junghoon, E-mail: jleenano@snu.ac.kr [Department of Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul (Korea, Republic of); Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Division of WCU Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of)

    2014-08-04

    We report direct printing and photo-thermal reduction of graphite oxide (GO) to obtain a highly porous pattern of interdigitated electrodes, leading to a supercapacitor on a flexible substrate. Key parameters optimized include the amount of GO delivered, the suitable photo-thermal energy level for effective flash reduction, and the substrate properties for appropriate adhesion after reduction. Tests with supercapacitors based on the printed-reduced GO showed performance comparable with commercial supercapacitors: the energy densities were 1.06 and 0.87 mWh/cm{sup 3} in ionic and organic electrolytes, respectively. The versatility in the architecture and choice of substrate makes this material promising for smart power applications.

  2. Reduction reaction analysis of nanoparticle copper oxide for copper direct bonding using formic acid

    Science.gov (United States)

    Fujino, Masahisa; Akaike, Masatake; Matsuoka, Naoya; Suga, Tadatomo

    2017-04-01

    Copper direct bonding is required for electronics devices, especially power devices, and copper direct bonding using formic acid is expected to lower the bonding temperature. In this research, we analyzed the reduction reaction of copper oxide using formic acid with a Pt catalyst by electron spin resonance analysis and thermal gravimetry analysis. It was found that formic acid was decomposed and radicals were generated under 200 °C. The amount of radicals generated was increased by adding the Pt catalyst. Because of these radicals, both copper(I) oxide and copper(II) oxide start to be decomposed below 200 °C, and the reduction of copper oxide is accelerated by reactants such as H2 and CO from the decomposition of formic acid above 200 °C. The Pt catalyst also accelerates the reaction of copper oxide reduction. Herewith, it is considered that the copper surface can be controlled more precisely by using formic acid to induce direct bonding.

  3. Solid oxide membrane process for the direct reduction of magnesium from magnesium oxide

    Science.gov (United States)

    Krishnan, Ajay

    The Solid Oxide Membrane (SOM) process is an emerging generic technology for the environmentally friendly extraction of high-energy-content metals directly from their oxides. This process has the potential to offer a viable, cost effective and cleaner alternative to existing state of the art primary magnesium extraction processes. The SOM process in principle uses a tubular yttria stabilized-zirconia-based solid oxide fuel cell with liquid metal (copper or tin) as an anode in the temperature range of 1100--1300°C. Magnesium oxide is dissolved in a molten ionic flux and oxygen ions are pumped out of the flux through the zirconia membrane and are oxidized at, the liquid metal anode. Magnesium vapor evolves at the cathode and is condensed in a separate chamber (condenser). The proof of concept for the SOM process was initially demonstrated at 1300°C using a magnesium fluoride-based flux. Since the membrane is the most expensive part of the process, its long-term stability is critical to the scale up and eventual commercialization of the process. Temperature, flux chemistry and cell operating conditions have been identified as key process parameters for membrane stability. A new low temperature flux based on the eutectic: magnesium fluoride-calcium fluoride system, has been developed which has lowered the operating temperature of the SOM cell to 1150°C. Additionally, a minor addition of yttrium fluoride to the flux minimized yttria diffusion from the yttria-stabilized-zirconia membrane, thereby further enhancing membrane stability. Important thermo-physical properties of the selected flux compositions critical to the process such as viscosity, density, volatility, solubility and electrical conductivity have been measured. The SOM cell has been electrochemically characterized and concepts related to MgO dissociation voltage, observed leakage current and mass transfer in the SOM cell are explained. The viability of the SOM process has been demonstrated by the

  4. Direct Reduction of Graphene Oxide by Ni Foam as a High-Capacitance Supercapacitor Electrode.

    Science.gov (United States)

    Yang, Jing; Zhang, Enwei; Li, Xiaofeng; Yu, Yunhua; Qu, Jin; Yu, Zhong-Zhen

    2016-01-27

    Three dimensional reduced graphene oxide (RGO)/Ni foam composites are prepared by a facile approach without using harmful reducing agents. Graphene oxide is reduced by Ni foam directly in its aqueous suspension at pH 2 at room temperature, and the resultant RGO sheets simultaneously assemble around the pillars of the Ni foam. The RGO/Ni foam composite is used as a binder-free supercapacitor electrode and exhibits high electrochemical properties. Its areal capacitance is easily tuned by varying the reduction time for different RGO loadings. When the reduction time increases from 3 to 15 days, the areal capacitance of the composite increases from 26.0 to 136.8 mF cm(-2) at 0.5 mA cm(-2). Temperature is proven to be a key factor in influencing the reduction efficiency. The composite prepared by 5 h reduction at 70 °C exhibits even better electrochemical properties than its counterpart prepared by 15 day reduction at ambient temperature. The 5 h RGO/Ni foam composite shows an areal capacitance of 206.7 mF cm(-2) at 0.5 mA cm(-2) and good rate performance and cycling stability with areal capacitance retention of 97.4% after 10000 cycles at 3 mA cm(-2). Further extending the reduction time to 9 h at 70 °C, the composite shows a high areal capacitance of 323 mF cm(-2) at 0.5 mA cm(-2). Moreover, the good rate performance and cycling stability are still maintained.

  5. A New Direction for Biomining: Extraction of Metals by Reductive Dissolution of Oxidized Ores

    Directory of Open Access Journals (Sweden)

    Kevin B. Hallberg

    2013-01-01

    Full Text Available Biomining, the biotechnology that uses microorganisms to extract metals from ores and concentrates, is currently used exclusively for processing reduced ores and mine wastes. Metals of economic value also occur extensively in oxidized ores, such as nickel laterites. While these are not amenable to oxidative dissolution, the ferric iron minerals they contain can, in theory, be disrupted by iron reduction, causing associated metals to be released. We have harnessed the ability of the facultatively anaerobic, acidophilic bacterium Acidithiobacillus ferroooxidans to couple the oxidation of elemental sulphur to the reduction of ferric iron in the goethite fraction of a limonitic nickel ore at 30 °C. Nickel and other metals (Co, Cr and Mn were effectively solubilised and maintained in solution due to the low pH (1.8 of the leach liquor. The results highlight the potential for the bioprocessing of oxidized, iron-rich ores using an approach that is energy-saving and environmentally-benign compared with metallurgical processes currently applied to the extraction of Ni from lateritic ores.

  6. Achieving direct electrochemistry of glucose oxidase by one step electrochemical reduction of graphene oxide and its use in glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Shamsipur, Mojtaba; Amouzadeh Tabrizi, Mahmoud, E-mail: mahmoud.tabrizi@gmail.com

    2014-12-01

    In this paper, the direct electrochemistry of glucose oxidase (GOD) was accomplished at a glassy carbon electrode modified with electrochemically reduced graphene oxide/sodium dodecyl sulfate (GCE/ERGO/SDS). A pair of reversible peaks is exhibited on GCE/ERGO/SDS/GOD by cyclic voltammetry. The peak-to-peak potential separation of immobilized GOD is 28 mV in 0.1 M phosphate buffer solution (pH 7.0) with a scan rate of 50 mV/s. The average surface coverage is 2.62 × 10{sup −10} mol cm{sup −2}. The resulting biosensor exhibited a good response to glucose with linear range from 1 to 8 mM (R{sup 2} = 0.9878), good reproducibility and detection limit of 40.8 μM. The results from the biosensor were similar (± 5%) to those obtained from the clinical analyzer. - Highlights: • A direct electron transfer reaction of glucose oxidase was observed on GCE/ERGO/SDS. • This composite film was successfully applied in preparation of glucose biosensor. • The detection limit of the biosensor was estimated to be 40.8 μM. • The results from the sensor were similar to those obtained from the clinical analyzer.

  7. Reduction property of rare earth oxide doped molybdenum oxide

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Rare earth oxide doped molybdenum powders were prepared by the reduction of rare earth nitrites doped MoO3. The effect of rare earth oxide on the reduction behavior of molybdenum oxide had been studied by means of Temperature Programmed Reduction (TPR), thermal analysis, X-ray diffraction. Doping rare earth oxide in the powder could lower the reduction temperature of molybdenum oxide and decrease the particle size of molybdenum. The mechanism for the effects had been discussed in this paper.

  8. Recovery of Iron from Copper Tailings by Direct Reduction

    Science.gov (United States)

    Gu, Jing; Xia, De-Hong; Gu, Jing; Liu, Kai-Qi; Zhang, Feng; Wang, Shou-Zeng; Qi, Zhao-Dong; Ao, Wen-Qing

    2016-05-01

    Direct reduction of copper tailings were performed to recover iron efficiently by carbon-containing pellets, and the metallization rate was gained by chemical analysis method. The results showed that the metallization rate of copper tailings was up to 85.32% and the best reduction parameters are also found. Content of precious metals, such as, gold, silver in copper tailings can be enriched by 1.8~1.9 times through removing iron. The apparent activation energy of direct reduction of iron oxide in copper tailings is calculated to be 125.4 kJ/mol and the restrictive factor of reduction process is solid diffusion.

  9. Oxidation and Reduction Reactions in Organic Chemistry

    Science.gov (United States)

    Shibley, Ivan A., Jr.; Amaral, Katie E.; Aurentz, David J.; McCaully, Ronald J.

    2010-01-01

    A variety of approaches to the concept of oxidation and reduction appear in organic textbooks. The method proposed here is different than most published approaches. The oxidation state is calculated by totaling the number of heterogeneous atoms, [pi]-bonds, and rings. A comparison of the oxidation states of reactant and product determine what type…

  10. Oxidation and Reduction Reactions in Organic Chemistry

    Science.gov (United States)

    Shibley, Ivan A., Jr.; Amaral, Katie E.; Aurentz, David J.; McCaully, Ronald J.

    2010-01-01

    A variety of approaches to the concept of oxidation and reduction appear in organic textbooks. The method proposed here is different than most published approaches. The oxidation state is calculated by totaling the number of heterogeneous atoms, [pi]-bonds, and rings. A comparison of the oxidation states of reactant and product determine what type…

  11. Biomimetic and microbial reduction of nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Potter, W.T.; Le, U.; Ronda, S. [Univ. of Tulsa, OK (United States)] [and others

    1995-12-31

    The biomimetic reduction of nitric oxide (NO) to nitrous oxide (N{sub 2}O) by dithiothreitol in the presence of cyanocobalamin and cobalt-centered porphyrins has been investigated. Reactions were monitored directly using Fourier Transform Infrared (FTIR) Spectroscopy vapor-phase spectra. Reaction rates were twofold faster for the corrin than for the cobalt-centered porphyrins. The stoichiometry showed the loss of two molecules of NO per molecule of N{sub 2}O produced. We have also demonstrated that the facultative anaerobe and chemoautotroph, Thiobacillus denitrificans, can be cultured anoxically in batch reactors using NO as a terminal electron acceptor with reduction to elemental nitrogen (N{sub 2}). We have proposed that the concentrated stream of NO{sub x}, as obtained from certain regenerable processes for the gas desulfurization and NO{sub x} removal, could be converted to N{sub 2} for disposal by contact with a culture of T. denitrificans. Four heterotrophic bacteria have also been identified that may be grown in batch cultures with succinate, yeast extract, or heat and alkali pretreated sewage sludge as carbon and energy sources and NO as a terminal electron acceptor. These are Paracoccus dentrificans, Pseudomonas denitrificans, Alcaligens denitrificans, and Thiophaera pantotropha.

  12. State of the direct reduction and reduction smelting processes

    Directory of Open Access Journals (Sweden)

    Markotić A.

    2002-01-01

    Full Text Available For quite a long time efforts have been made to develop processes for producing iron i.e. steel without employing conventional procedures - from ore, coke, blast furnace, iron, electric arc furnace, converter to steel. The insufficient availability and the high price of the coking coals have forced many countries to research and adopt the non-coke-consuming reduction and metal manufacturing processes (non-coke metallurgy, direct reduction, direct processes. This paper represents a survey of the most relevant processes from this domain by the end of 2000, which display a constant increase in the modern process metallurgy.

  13. Solvothermal reduction of graphene oxide in dimethylformamide

    Science.gov (United States)

    Kim, Sujin; Choi, Kwangrok; Park, Sungjin

    2016-11-01

    The reduction of graphene oxide (G-O) is one of the most promising methods for the large scale production of graphene-based materials. In this paper, we report a simple and non-toxic method to produce reduced graphene oxide (rG-O) by refluxing G-O in N, N-dimethylformamide without the aid of a reducing agent. The rG-O materials with high degrees of reduction are prepared and the levels of reduction are controlled using reflux time. Successful reduction is confirmed by combustion-based elemental analysis and X-ray photoelectron and Fourier transform infrared spectroscopy.

  14. Dechlorination by combined electrochemical reduction and oxidation

    Institute of Scientific and Technical Information of China (English)

    CONG Yan-qing; WU Zu-cheng; TAN Tian-en

    2005-01-01

    Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate was more than 90% by the combined electrochemical reduction and oxidation at current of 6 mA and pH 6. The hydrogen atom is a powerful reducing agent that reductively dechlorinates chlorophenols. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the degradation of chlorophenol.

  15. Stabilized tin-oxide-based oxidation/reduction catalysts

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Leighty, Bradley D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor); Gulati, Suresh T. (Inventor); Summers, Jerry C. (Inventor)

    2008-01-01

    The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

  16. Graphite Oxide: Structure, Reduction and Applications

    Science.gov (United States)

    Gao, Wei

    This thesis proposes a modified structure model for graphite oxide (GO), an important precursor in graphene chemistry, develops a new strategy to convert GO back to graphene-like structure, and demonstrates its possible applications in both water purification and supercapacitor technologies. GO, a nontraditional compound first obtained from graphite oxidation over 150 years ago, is now becoming an important player in the production of graphene-based materials, which has high technological relevance. GO structure and reduction have been vigorously investigated, but its precise chemical structure still remains obscure, and the complete restoration of the sp2 carbon lattice has not yet been achieved. In our work, solid state 13C NMR (MAS) analysis offered a piece of evidence for five or six-membered ring lactol structure existing in GO that had never been assigned before, leading to a modified Lerf-Klinowski model for GO. A three-step reduction strategy, involving sodium borohydride (NaBH4), sulfuric acid, and high temperature thermal annealing, described in the thesis, successfully reduced GO back to chemically converted graphene (CCG) with the lowest heteroatom abundance among all those previously reported. In addition to the chemical significance of graphene/CCG production, GO and its derivatives were used as novel adsorbents in water purification. GO-coated sand showed higher retention than ordinary sand for both Rhodamine B and mercuric ion (Hg2+) contaminants in water. Further functionalization of GO with thiophenol resulted in better adsorption capacity toward Hg2+ than that of activated carbon. In addition, free-standing films of GO were treated and reduced with a CO 2 laser beam into different conductive reduced GO (RGO) patterns, and directly used as supercapacitor devices which showed good cyclic stability and energy storage capacities comparable to that of existing thin film ultracapacitors. GO turned out to be a solid electrolyte with anisotropic proton

  17. Electro-catalytic reduction of nitrogen oxides

    Energy Technology Data Exchange (ETDEWEB)

    McLarnon, C.R.

    1989-12-01

    Nitrogen oxides have been linked to a broad range of air pollution problems including acid rain and the atmospheric production of photochemical ozone. Over twenty million tons of nitrogen oxides are emitted into the atmosphere each year as a result of the high temperature combustion of fossil fuels. Efforts to control nitrogen oxides emissions have lagged because of the generally low discharge concentrations of nitrogen oxides in combustion exhaust and because nitrogen oxides are more difficult to remove due to their lower reactivity. No catalyst has yet been found that will achieve significant reduction of nitrogen oxides in an oxidizing environment. Oxygen in the exhaust stream competes with nitrogen oxides for the active catalyst sites. Also, the dissociated oxygen atoms produced by decomposition of nitrogen oxides deactivate the surface of the catalyst. Externally applied electric fields have been used to control oxygen adsorption on metal and semi-conductor surfaces. In this investigation, a stream containing nitric oxide has been subjected to intense electric fields in the presence of catalyst materials including steel, stainless steel, and gold plated stainless steel wools and glass wool. The electric fields have been generated using DC, AC and rectified AC potentials in the range of 0--20 KV. The effect of parameters such as inlet nitric oxide concentration, oxygen and water content, gas residence time and temperature have also been studied.

  18. Large Scale Reduction of Graphite Oxide Project

    Science.gov (United States)

    Calle, Carlos; Mackey, Paul; Falker, John; Zeitlin, Nancy

    2015-01-01

    This project seeks to develop an optical method to reduce graphite oxide into graphene efficiently and in larger formats than currently available. Current reduction methods are expensive, time-consuming or restricted to small, limited formats. Graphene has potential uses in ultracapacitors, energy storage, solar cells, flexible and light-weight circuits, touch screens, and chemical sensors. In addition, graphite oxide is a sustainable material that can be produced from any form of carbon, making this method environmentally friendly and adaptable for in-situ reduction.

  19. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    H.Y. Sohn

    2008-03-31

    The objective of the project is to develop a new ironmaking technology based on hydrogen and fine iron oxide concentrates in a suspension reduction process. The ultimate objective of the new technology is to replace the blast furnace and to drastically reduce CO2 emissions in the steel industry. The goals of this phase of development are; the performance of detailed material and energy balances, thermochemical and equilibrium calculations for sulfur and phosphorus impurities, the determination of the complete kinetics of hydrogen reduction and bench-scale testing of the suspension reduction process using a large laboratory flash reactor.

  20. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    H.Y. Sohn

    2008-03-31

    The objective of the project is to develop a new ironmaking technology based on hydrogen and fine iron oxide concentrates in a suspension reduction process. The ultimate objective of the new technology is to replace the blast furnace and to drastically reduce CO2 emissions in the steel industry. The goals of this phase of development are; the performance of detailed material and energy balances, thermochemical and equilibrium calculations for sulfur and phosphorus impurities, the determination of the complete kinetics of hydrogen reduction and bench-scale testing of the suspension reduction process using a large laboratory flash reactor.

  1. Green reduction of graphene oxide using alanine.

    Science.gov (United States)

    Wang, Jiabin; Salihi, Elif Caliskan; Šiller, Lidija

    2017-03-01

    There remains a real need for the easy, eco-friendly and scalable preparation method of graphene due to various potential applications. Chemical reduction is the most versatile method for the large scale production of graphene. Here we report the operating conditions for a one-step, economical and green synthesis method for the reduction of graphene oxide using a biomolecule (alanine). Graphene oxide was produced by the oxidation and exfoliation of natural graphite flake with strong oxidants using Hummers method (Hummers and Offeman, 1958), but the method was revised in our laboratory to set up a safe and environmentally friendly route. The reduction of graphene oxide was investigated using alanine at various operating conditions in order to set up optimum conditions (treatment time, temperature and concentration of the reagent). Samples have been characterized by using UV-Visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, Raman spectroscopy and X-ray diffraction analysis. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  2. Voltage-induced reduction of graphene oxide

    Science.gov (United States)

    Faucett, Austin C.

    Graphene Oxide (GO) is being widely researched as a precursor for the mass production of graphene, and as a versatile material in its own right for flexible electronics, chemical sensors, and energy harvesting applications. Reduction of GO, an electrically insulating material, into reduced graphene oxide (rGO) restores electrical conductivity via removal of oxygen-containing functional groups. Here, a reduction method using an applied electrical bias, known as voltage-induced reduction, is explored. Voltage-induced reduction can be performed under ambient conditions and avoids the use of hazardous chemicals or high temperatures common with standard methods, but little is known about the reduction mechanisms and the quality of rGO produced with this method. This work performs extensive structural and electrical characterization of voltage-reduced GO (V-rGO) and shows that it is competitive with standard methods. Beyond its potential use as a facile and eco-friendly processing approach, V-rGO reduction also offers record high-resolution patterning capabilities. In this work, the spatial resolution limits of voltage-induced reduction, performed using a conductive atomic force microscope probe, are explored. It is shown that arbitrary V-rGO conductive features can be patterned into insulating GO with nanoscale resolution. The localization of voltage-induced reduction to length scales < 10 nm allows studies of reduction reaction kinetics, using electrical current obtained in-situ, with statistical robustness. Methods for patterning V-rGO nanoribbons are then developed. After presenting sub-10nm patterning of V-rGO nanoribbons in GO single sheets and films, the performance of V-rGO nanoribbon field effect transistors (FETs) are demonstrated. Preliminary measurements show an increase in electrical current on/off ratios as compared to large-area rGO FETs, indicating transport gap modulation that is possibly due to quantum confinement effects.

  3. Thermodynamic constraints on microbial iron oxide reduction

    Science.gov (United States)

    Bonneville, S.; Behrends, T.; Haese, R.; van Cappellen, P.

    2003-04-01

    Iron oxides are ubiquitous reactive constituents of soils, sediments and aquifers. They exhibit large surface areas which bind trace metals, nutrients and organic molecules. Under suboxic conditions, iron oxides can reductively dissolve via several abiotic and microbial pathways. In particular, they serve as terminal electron acceptors for the oxidation of organic matter by iron reducing bacteria. The aim of our study was to determine the thermodynamic energy yields of dissimilatory iron reduction for different Fe(III) substrates. We used the facultative anaerobic gram-positive bacterium Shewanella putrefaciens as model iron reducing bacterium, with ferrihydrite, hematite, goethite or Fe(III)-salicylate as electron acceptor, and lactate as electron donor. Experiments were conducted in an anaerobic pH-stat batch reactor, equipped with a polarographic electrode to monitor in situ the dissolved ferrous iron activity. The stoichiometry of total Fe(II) production and acid consumption during the experiments indicated that lactate was oxidized to acetate. From the Fe(II) activity and redox potential measurements, free energy yields were calculated for Fe(III) reduction coupled to lactate oxidation. The results showed that the redox potential of the overall reaction was poised by equilibrium between the Fe(III)-substrate and aqueous Fe(II). Hence, the energy yields decreased in the order ferrihydrite > Fe(III)-salicylate > hematite > goethite. Accumulation of Fe(II) in solution only caused small decreases in the energy yields over the course of the experiments. Cessation of iron reduction, which was observed in all experiments, was therefore not due to thermodynamic limitation, but more likely reflected the decline in cell level of activity.

  4. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  5. Oxidation-reduction catalyst and its process of use

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor)

    2008-01-01

    This invention relates generally to a ruthenium stabilized oxidation-reduction catalyst useful for oxidizing carbon monoxide, and volatile organic compounds, and reducing nitrogen oxide species in oxidizing environments, substantially without the formation of toxic and volatile ruthenium oxide species upon said oxidizing environment being at high temperatures.

  6. Reduction Behaviors of Carbon Composite Iron Oxide Briquette Under Oxidation Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ki-Woo; Kim, Kang-Min; Kwon, Jae-Hong; Han, Jeong-Whan [Inha University, Incheon (Korea, Republic of); Son, Sang-Han [POSCO, Pohang (Korea, Republic of)

    2017-01-15

    The carbon composite iron oxide briquette (CCB) is considered a potential solution to the upcoming use of low grade iron resources in the ironmaking process. CCB is able to reduce raw material cost by enabling the use of low grade powdered iron ores and coal. Additionally, the fast reduction of iron oxides by direct contact with coal can be utilized. In this study, the reduction behaviors of CCB were investigated in the temperature range of 200-1200 ℃ under oxidizing atmosphere. Briquettes were prepared by mixing iron ore and coal in a weight ratio of 8:2. Then reduction experiments were carried out in a mixed gas atmosphere of N{sub 2}, O{sub 2}, and CO{sub 2}. Compressive strength tests and quantitative analysis were performed by taking samples at each target temperature. In addition, the reduction degree depending on the reaction time was evaluated by off-gas analysis during the reduction test. It was found that the compressive strength and the metallization degree of the reduced briquettes increased with increases in the reaction temperature and holding time. However, it tended to decrease when the re-oxidation phenomenon was caused by injected oxygen. The degree of reduction reached a maximum value in 26 minutes. Therefore, the re-oxidation phenomenon becomes dominant after 26 minutes.

  7. Electrochemical reduction of metal oxides in molten salts for nuclear reprocessing

    OpenAIRE

    Abdulaziz, R.

    2016-01-01

    This thesis examines the electrochemical reduction of metal oxides in molten salts for nuclear reprocessing applications. The objective of this research is to characterise and understand the direct electrochemical reduction of UO₂ to U metal in a LiCl-KCl molten salt eutectic, as part of the nuclear pyroprocessing scheme, following a similar approach to the FFC Cambridge for the reduction of TiO₂ to Ti metal. The voltammetric behaviour of reduction processes of metal oxides were evaluated usi...

  8. Direct iron ore reduction by methane in a fluidized bed. Final report, November 1989-December 1992

    Energy Technology Data Exchange (ETDEWEB)

    van der Vaart, D.R.; Conger, W.L.

    1993-08-01

    Novel process chemistry of methane in a fluidized bed was investigated to identify a more direct route to producing the reducing gas needed in the Direct Reduction of iron ore. A rather surprising result, however, of the study was the discovery of an inexpensive and attrition-resistant catalytic material for methane oxidative coupling. The iron oxide impregnated, non-porous silica oxide was found to be relatively active, and quite selective when steam was added to the methane/air feed.

  9. Safeguard monitoring of direct electrolytic reduction

    Science.gov (United States)

    Jurovitzki, Abraham L.

    Nuclear power is regaining global prominence as a sustainable energy source as the world faces the consequences of depending on limited fossil based, CO2 emitting fuels. A key component to achieving this sustainability is to implement a closed nuclear fuel cycle. Without achieving this goal, a relatively small fraction of the energy value in nuclear fuel is actually utilized. This involves recycling of spent nuclear fuel (SNF)---separating fissile actinides from waste products and using them to fabricate fresh fuel. Pyroprocessing is a viable option being developed for this purpose with a host of benefits compared to other recycling options, such as PUREX. Notably, pyroprocessing is ill suited to separate pure plutonium from spent fuel and thus has non-proliferation benefits. Pyroprocessing involves high temperature electrochemical and chemical processing of SNF in a molten salt electrolyte. During this batch process, several intermediate and final streams are produced that contain radioactive material. While pyroprocessing is ineffective at separating pure plutonium, there are various process misuse scenarios that could result in diversion of impure plutonium into one or more of these streams. This is a proliferation risk that should be addressed with innovative safeguards technology. One approach to meeting this challenge is to develop real time monitoring techniques that can be implemented in the hot cells and coupled with the various unit operations involved with pyroprocessing. Current state of the art monitoring techniques involve external chemical assaying which requires sample removal from these unit operations. These methods do not meet International Atomic Energy Agency's (IAEA) timeliness requirements. In this work, a number of monitoring techniques were assessed for their viability as online monitoring tools. A hypothetical diversion scenario for the direct electrolytic reduction process was experimentally verified (using Nd2O3 as a surrogate for PuO2

  10. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2017-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s......Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon...

  11. Catalyst for reduction of nitrogen oxides

    Science.gov (United States)

    Ott, Kevin C.

    2010-04-06

    A Selective Catalytic Reduction (SCR) catalyst was prepared by slurry coating ZSM-5 zeolite onto a cordierite monolith, then subliming an iron salt onto the zeolite, calcining the monolith, and then dipping the monolith either into an aqueous solution of manganese nitrate and cerium nitrate and then calcining, or by similar treatment with separate solutions of manganese nitrate and cerium nitrate. The supported catalyst containing iron, manganese, and cerium showed 80 percent conversion at 113 degrees Celsius of a feed gas containing nitrogen oxides having 4 parts NO to one part NO.sub.2, about one equivalent ammonia, and excess oxygen; conversion improved to 94 percent at 147 degrees Celsius. N.sub.2O was not detected (detection limit: 0.6 percent N.sub.2O).

  12. Technologies for the Reduction of Nitrogen Oxides Emissions

    Directory of Open Access Journals (Sweden)

    Paulica Arsenie

    2015-06-01

    Full Text Available When it comes to gas turbines, their main problem concerning pollutant emissions is represented by nitric oxides. Among other emissions, sulphur oxides being much reduced due to the use of liquid distilled and gas fuels with a low content of sulphur. Using water or steam injection became the favourite method during the '80s and especially the '90s since "dry" methods and catalytic reduction were both at the beginning of the development phase. Catalytic convertors have been used since the '80s and they are still used although the costs of renewing the catalyst are very high. In the last twenty years a gradual decrease has been registered on the limits of nitric oxides from 75 ppm to 25 ppm, and now the target is oriented towards the 9 ppm level. The evolution of burning technologies of combustion makes it possible to control the level of production of nitric oxides even from the source without being necessary to use "humid" methods. This, of course, opened the market for gas turbines because they can function even in areas with limited quality water reserves, such as maritime platforms and in the desert. In this paper, we are going to show that, although water injection is still used, "dry" control technologies of burning became favourite methods for the majority of users on the industrial power generators market. The great dependency between the creation of nitric oxides and the temperature reveals the effect of direct water or steam injection on reducing nitric oxides. Recent research showed that a reduction up to 85% of nitric oxides may be obtained by using the water or steam injection all together with the improvement of aerodynamic character of the burning room.

  13. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide;

    2015-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s...

  14. Simultaneous iridium catalysed oxidation and enzymatic reduction employing orthogonal reagents.

    Science.gov (United States)

    Mutti, Francesco G; Orthaber, Andreas; Schrittwieser, Joerg H; de Vries, Johannes G; Pietschnig, Rudolf; Kroutil, Wolfgang

    2010-11-14

    An iridium catalysed oxidation was coupled concurrently to an asymmetric biocatalytic reduction in one-pot; thus it was shown for the first time that iridium- and alcohol dehydrogenase-catalysed redox reactions are compatible. As a model system racemic chlorohydrins were transformed to enantioenriched chlorohydrins via an oxidation-asymmetric reduction sequence.

  15. Graphene oxide reduction recipes, spectroscopy, and applications

    CERN Document Server

    Gao, Wei

    2015-01-01

    This book focuses on a group of new materials labeled ""graphene oxides."" It provides a comprehensive overview of graphene oxide-based nanomaterials in terms of their synthesis, structures, properties, and extensive applications in catalysis, separation, filtration, energy storage and conversion. The book also covers emerging research on graphite oxides and the impact of the research on fundamental and applied sciences.

  16. Development of Direct Reduction Process and Smelting Reduction Processes for the Steel Production

    Directory of Open Access Journals (Sweden)

    Kožuh S.

    2006-01-01

    Full Text Available Although the blast furnace and basic oxygen furnace are going to be primary routes for steel production in future, the steelmaking industry using the electric arc furnace route will continue to grow. The importance of high-quality steel products manufactured by direct reduction of iron ore and/or by smelting reduction processes has been increasing. In the past decade the world steel production by direct reduction rose by 140 per cent, from about 20 to about 49.5 Mt/year. In this paper major industrial processes involving direct reduction and smelting reduction of iron ore are described, and their development is analysed.

  17. Direct Oxidation of Ethene to Acetic Acid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Direct oxidation of ethene to acetic acid over Pd-SiW12/SiO2 catalysts prepared by several methods was studied. A better method for reducing palladium composition of the catalysts was found. Acetic acid was obtained with selectivity of 82.7% and once-through space time yield (STY) of 257.4 g/h×L.

  18. Oxidation and Reduction: Too Many Definitions?

    Science.gov (United States)

    Silverstein, Todd P.

    2011-01-01

    IUPAC gives several different definitions of oxidation: loss of electrons, increase in oxidation state, loss of hydrogen, or gain of oxygen. Most introductory or general chemistry textbooks use all of these definitions at one time or another, which can lead to some confusion in the minds of first-year chemistry students. Some paradoxical…

  19. Oxidation and Reduction: Too Many Definitions?

    Science.gov (United States)

    Silverstein, Todd P.

    2011-01-01

    IUPAC gives several different definitions of oxidation: loss of electrons, increase in oxidation state, loss of hydrogen, or gain of oxygen. Most introductory or general chemistry textbooks use all of these definitions at one time or another, which can lead to some confusion in the minds of first-year chemistry students. Some paradoxical…

  20. Restraining Sodium Volatilization in the Ferric Bauxite Direct Reduction System

    Directory of Open Access Journals (Sweden)

    Wentao Hu

    2016-03-01

    Full Text Available Direct reduction is an emerging utilization technology of ferric bauxite. However, it requires much more sodium carbonate than ordinary bauxite does. The volatilization is one of the most significant parts of sodium carbonate consumption, as reported in previous studies. Based on the new direct reduction method for utilization of ferric bauxite, this paper has systematically investigated factors including heating temperature, heating time, and sodium carbonate dosage influencing sodium volatilization. For the purpose of reducing sodium volatilization, the Box–Benhken design was employed, and the possibility of separating iron and sodium after direct reduction was also investigated.

  1. Reduction of chromium oxide from slags

    Directory of Open Access Journals (Sweden)

    Gutiérrez-Paredes, J.

    2005-12-01

    Full Text Available Experimental and theoretical work were performed to estimate the effect of slag basicity and amount of reducing agents on the reduction of chromium oxide from the slag which interacted with molten steel at 1,600 °C. The slag system contained CaO, MgO, SiO2, CaF2 and Cr2O3 together with Fe-alloys (Fe-Si and Fe-Si-Mg. The CaF2 and MgO contents in the slags were 10 mass % each; Cr2O3 was 25%. The amount of the ferroalloys ranged from 12.5 to 50 g per 100 g of slag. The (CaO+MgO/SiO2 ratio was held at 1 and 2. The Cr yield was determined using both Fe-alloys as reducing agents. Some estimations were made to determine the theoretical effect of temperature, slag basicity, (CaO+MgO/SiO2, and amount of reducing agents in the slag on the chromium recovery. The FACT (Facility for the Analysis of Chemical Thermodynamics computational package is used to determine the equilibrium between the slag and molten steel.

    En el presente trabajo se realiza un estudio teórico y experimental para determinar el efecto de la basicidad de la escoria y la cantidad de agentes reductores sobre la reducción de óxidos de cromo contenidos en la escoria, la cual está en contacto con acero líquido a 1.600 °C. La escoria se prepara con los reactivos CaO, MgO, SiO2, CaF2 y ferroaleaciones (Fe-Si y Fe-Si-Mg. Los contenidos de CaF2 y MgO en la escoria son de 10 %, cada uno, y el de Cr2O3 es 25 %. La cantidad de la ferroaleación varía de 12,5 a 50 g por cada 100 g de escoria. La relación (CaO+MgO/SiO2 tiene los valores de 1 y 2. Se determina la eficiencia de recuperación de cromo empleando los dos tipos de ferroaleaciones. Se realizaron cálculos para determinar el efecto teórico de la temperatura, la basicidad de la escoria, (CaO+MgO/SiO2, y la cantidad de agentes reductores sobre la reducci

  2. [Competitive Microbial Oxidation and Reduction of Arsenic].

    Science.gov (United States)

    Yang, Ting-ting; Bai, Yao-hui; Liang, Jin-song; Huo, Yang; Wang, Ming-xing; Yuan, Lin-ijang

    2016-02-15

    Filters are widely applied in drinking water treatment plants. Our previous study, which explored the asenic redox in a filter of drinking water plant treating underground water, found that As3+ could be oxidized to As5+ by biogenic manganese oxides, while As5+ could be reduced to As3+ by some microbial arsenic reductases in the biofilter system. This microbial competition could influence the system stability and treatment efficiency. To explore its mechanism, this study selected a manganese-oxidizing bacterial strain (Pseudomonas sp. QJX-1) and a arsenic-reducing strain (Brevibacterium sp. LSJ-9) to investigate their competitive relationship in nutrient acquisition and arsenic redox in the presence of Mn2+, As3+ or As5+ The results revealed that the concentration and valence of Mn and As varied with different reaction time; biological manganese oxides dominated the arsenic redox by rapidly oxidizing the As3+ in the existing system and the As3+ generated by arsenic reductase into As. PCR and RT-PCR results indicated that the arsenic reductase (arsC) was inhibited by the manganese oxidase (cumA). The expression of 16S rRNA in QJX-1 was two orders of magnitude higher than that in LSJ-9, which implied QJX-1 was dominant in the bacterial growth. Our data revealed that hydraulic retention time was critical to the valence of arsenic in the effluent of filter in drinking water treatment plant.

  3. Comparative study of synthesis and reduction methods for graphene oxide

    KAUST Repository

    Alazmi, Amira

    2016-05-14

    Graphene oxide (GO) and reduced graphene oxide (rGO) have congregated much interest as promising active materials for a variety of applications such as electrodes for supercapacitors. Yet, partially given the absence of comparative studies in synthesis methodologies, a lack of understanding persists on how to best tailor these materials. In this work, the effect of using different graphene oxidation-reduction strategies in the structure and chemistry of rGOs is systematically discussed. Two of the most popular oxidation routes in the literature were used to obtain GO. Subsequently, two sets of rGO powders were synthesised employing three different reduction routes, totalling six separate products. It is shown that the extension of the structural rearrangement in rGOs is not just dependent on the reduction step but also on the approach followed for the initial graphite oxidation.

  4. Nitric oxide: an intermediate in nitrate reduction in Klebsiella pneumoniae

    Energy Technology Data Exchange (ETDEWEB)

    Al-Abdulla, J.M.; Aleem, M.I.H.

    1977-01-01

    When K. pneumoniae cells were grown anaerobically with nitrate as the final electron acceptor, there was a rapid reduction of nitrate to nitrite. The latter was further reduced to hydroxylamine and finally to ammonia. Nitrate, nitrite and nitric oxide, but not nitrous oxide, could accept electrons from the respiratory chain. During growth of the organism it was possible to trap nitric oxide with alkaline permanganate. The trapped gas represented only a small portion of the reduced electron acceptor. It would appear that a major portion of nitric oxide produced from nitrite reduction must be converted to an unknown nitrogenous intermediate with an oxidation state of +1 before its reduction to hydroxylamine. The possible nature of this elusive intermediate should be discussed.

  5. Carbothermic Reduction of Zinc Oxide Concentrate by Microwave

    Institute of Scientific and Technical Information of China (English)

    Ali Saidi; Kamran Azari

    2005-01-01

    Industrial application of microwave, as a heating source for material processing, was reviewed. The feasibility of carbothermic reduction of zinc oxide concentrate, as well as the effect of operating parameters was investigated,using a home style microwave oven at 2.45 GHz. Zinc oxide concentrate does not effectively absorb microwave energy, while any source of carbon, which is used as the reduction agent, absorbs microwave energy very well. In this respect coke breeze was found to be the best, and thus, coke was used both as the reducing agent and the absorbent of microwave energy. It was also found that any increase in the carbon content and size, increases the reduction rate. Increasing the microwave power and the size of the sample could also increase the reduction rate. Further investigation shows that when zinc oxide is exposed to the microwave for some time, the rate of the reduction by conventional method increases.

  6. Influence of temperature and voltage on electrochemical reduction of graphene oxide

    Indian Academy of Sciences (India)

    Xiuqiang Li; Dong Zhang; Peiying Zhu; Chao Yang

    2014-05-01

    In this paper, the influence of temperature and voltage on direct electrochemical reduction were discussed in detail. Reduced graphene oxide is characterized with X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT–IR) and field emission scanning electron microscopy (FE–SEM). It is found that the reduction degree of graphene oxide (GO) decreases gradually with the increase of applied temperature. The optimal applied temperature found in our experiment is 20 °C; Meanwhile, as the applied voltage increases from 0.1 to 12.5 V, the reduction degree of graphene oxide increases gradually. However, above 2.5 V, increasing voltage has little effect on the reduction degree of graphene oxide.

  7. C3 Epimerization of Glucose, via Regioselective Oxidation and Reduction

    NARCIS (Netherlands)

    Jumde, Varsha R.; Eisink, Niek N. H. M.; Witte, Martin D.; Minnaard, Adriaan J.

    2016-01-01

    Palladium-catalyzed oxidation can single out the secondary hydroxyl group at C3 in glucose, circumventing the more readily accessible hydroxyl at C6 and the more reactive anomeric hydroxyl. Oxidation followed by reduction results in either allose or allitol, each a rare sugar that is important in

  8. C-3 Epimerization of glucose, via regioselective oxidation and reduction

    NARCIS (Netherlands)

    Jumde, Varsha R; Eisink, Niek N H M; Witte, Martin D; Minnaard, Adriaan J

    2016-01-01

    Palladium catalysed oxidation is able to single out the secondary hydroxyl group at C3 in glucose, circumventing the more readily accessible hydroxyl at C6 and the more reactive anomeric hydroxyl. Oxidation followed by reduction results in either allose or allitol, rare sugars that are important in

  9. Nickel oxide reduction studied by environmental TEM

    DEFF Research Database (Denmark)

    Jeangros, Q.; Hansen, Thomas Willum; Wagner, Jakob Birkedal;

    2012-01-01

    In situ reduction of an industrial NiO powder is performed under 1.3 mbar of H2 (2 mlN/min) in a differentially pumped FEI Titan 80-300 environmental transmission electron microscope (ETEM). Images, diffraction patterns and electron energy loss spectra (EELS) are acquired to monitor the structura...

  10. Reduction of nitrogen oxides in aquous Fe-EDTA solutions

    NARCIS (Netherlands)

    Maas, van der P.M.F.; Sandt, van de T.; Klapwijk, A.; Lens, P.N.L.

    2003-01-01

    The reduction of nitric oxide (NO) in aqueous solutions of Fe(II)EDTA is one of the core processes in BioDeNOx, an integrated physicochemical and biological technique for NO, removal from industrial flue gases. NO reduction in aqueous solutions of Fe(II)EDTA (20-25 mM, pH 7.2 +/- 0.2) was

  11. A simple and efficient electrochemical reductive method for graphene oxide

    Indian Academy of Sciences (India)

    Yanyun Liu; Dong Zhang; Yu Shang; Chao Guo

    2014-10-01

    The electrochemical reduction of graphene oxide typically involves complicated procedures, such as modification of electrodes and preparation of electrolytes, which is often needed in previous reports. In this paper, a simple and efficient electrochemical process is described for the synthesis of high-quality reduced graphene oxide. The main procedures involve the electrophoretic deposition of graphene oxide onto positive electrode and the subsequent in situ electrochemical negative reduction when the electrode changes from positive to negative. This approach opens up a new, practical and green reducing method to prepare largescale graphene.

  12. Mathematical simulation of direct reduction process in zinc-bearing p ellets

    Institute of Scientific and Technical Information of China (English)

    Ying Liu; Fu-yong Su; Zhi Wen; Zhi Li; Hai-quan Yong; Xiao-hong Feng

    2013-01-01

    A one-dimensional unsteady mathematical model was established to describe direct reduction in a composite pellet made of metallurgical dust. The model considered heat transfer, mass transfer, and chemical reactions including iron oxide reductions, zinc oxide reduction and carbon gasification, and it was numerically solved by the tridiagonal matrix algorithm (TDMA). In order to verify the model, an experiment was performed, in which the profiles of temperature and zinc removal rate were measured during the reduction process. Results calculated by the mathematical model were in fairly good agreement with experimental data. Finally, the eff ects of furnace temperature, pellet size, and carbon content were investigated by model calculations. It is found that the pellet temperature curve can be divided into four parts according to heating rate. Also, the zinc removal rate increases with the increase of furnace temperature and the decrease of pellet size, and carbon content in the pellet has little influence on the zinc removal rate.

  13. Oxide reduction during triggered-lightning fulgurite formation

    Science.gov (United States)

    Jones, B. E.; Jones, K. S.; Rambo, K. J.; Rakov, V. A.; Jerald, J.; Uman, M. A.

    2005-03-01

    In this study triggered-lightning induced fulgurites were formed in 99.9% pure binary oxides of manganese (MnO) and nickel (NiO) in order to study oxide reduction mechanisms. The fulgurite formation process involved packing the oxide in PVC holders and using the standard rocket-and-wire technique to trigger a lightning strike through the oxide at the International Center for Lightning Research and Testing in Camp Blanding, Florida. These two oxides were chosen from the thermodynamic extrapolation of the oxide stability using the Ellingham Diagram. This diagram indicates that NiO is significantly less stable than MnO. Fulgurites from the pure oxides were analyzed in a scanning electron microscope (SEM); secondary electron images, backscattered images and energy dispersive spectroscopy (EDS) were used to determine the microstructure and composition of the fulgurites. SEM/EDS analysis of the NiO and MnO prior to fulgurite formation confirmed they were pure binary oxides with no metallic contamination. After fulgurite formation, it was found that the nickel oxide fulgurite contained metallic nickel particles; the manganese oxide fulgurite showed no metallic phase formation. Transmission electron microscopy (TEM) examination confirmed that the MnO was a pure oxide with no sign of metallic phase formation. However, TEM results of the NiO showed that approximately 50% of the NiO was reduced to metallic face-centered cubic Ni. The Ni and NiO were observed to be coherent with the [1 0 0]Ni//[1 0 0]NiO and [1 1 0]Ni//[1 1 0]NiO. These results are consistent with the aforementioned thermodynamic stability calculations and show that the presence of carbonaceous material or mixtures of oxides is not necessary for oxide reduction during fulgurite formation. These studies do not rule out the possibility that electrolysis plays a role in oxide reduction. However, these fulgurites were made simultaneously during the same lightning strike and therefore were subjected to the same

  14. Preliminary comparison of different reduction methods of graphene oxide

    Indian Academy of Sciences (India)

    Yu Shang; Dong Zhang; Yanyun Liu; Chao Guo

    2015-02-01

    The reduction of graphene oxide (GO) is a promising route to bulk produce graphene-based sheets. Different reduction processes result in reduced graphene oxide (RGO) with different properties. In this paper three reduction methods, chemical, thermal and electrochemical reduction, were compared on three aspects including morphology and structure, reduction degree and electrical conductivity by means of scanning electron microscopy (SEM), X-ray diffraction(XRD), the Fourier transform infrared spectroscopy (FT-IR) spectrum, X-ray photoelectron spectroscopy (XPS) and four-point probe conductivity measurement. Understanding the different characteristics of different RGO by preliminary comparison is helpful in tailoring the characteristics of graphene materials for diverse applications and developing a simple, green, and efficient method for the mass production of graphene.

  15. Reduction of Metal Oxide to Metal using Ionic Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Ramana Reddy

    2012-04-12

    A novel pathway for the high efficiency production of metal from metal oxide means of electrolysis in ionic liquids at low temperature was investigated. The main emphasis was to eliminate the use of carbon and high temperature application in the reduction of metal oxides to metals. The emphasis of this research was to produce metals such as Zn, and Pb that are normally produced by the application of very high temperatures. The reduction of zinc oxide to zinc and lead oxide to lead were investigated. This study involved three steps in accomplishing the final goal of reduction of metal oxide to metal using ionic liquids: 1) Dissolution of metal oxide in an ionic liquid, 2) Determination of reduction potential using cyclic voltammetry (CV) and 3) Reduction of the dissolved metal oxide. Ionic liquids provide additional advantage by offering a wide potential range for the deposition. In each and every step of the process, more than one process variable has been examined. Experimental results for electrochemical extraction of Zn from ZnO and Pb from PbO using eutectic mixtures of Urea ((NH2)2CO) and Choline chloride (HOC2H4N(CH3)3+Cl-) or (ChCl) in a molar ratio 2:1, varying voltage and temperatures were carried out. Fourier Transform Infra-Red (FTIR) spectroscopy studies of ionic liquids with and without metal oxide additions were conducted. FTIR and induction coupled plasma spectroscopy (ICPS) was used in the characterization of the metal oxide dissolved ionic liquid. Electrochemical experiments were conducted using EG&G potentiostat/galvanostat with three electrode cell systems. Cyclic voltammetry was used in the determination of reduction potentials for the deposition of metals. Chronoamperometric experiments were carried out in the potential range of -0.6V to -1.9V for lead and -1.4V to -1.9V for zinc. The deposits were characterized using XRD and SEM-EDS for phase, morphological and elemental analysis. The results showed that pure metal was deposited on the cathode

  16. Sequential electrolytic oxidation and reduction of aqueous phase energetic compounds.

    Science.gov (United States)

    Gilbert, David M; Sale, Tom C

    2005-12-01

    Contamination of soils and groundwater with energetic compounds has been documented at many former ammunition manufacturing plants and ranges. Recent research at Colorado State University (CSU) has demonstrated the potential utility of electrolytic degradation of organic compounds using an electrolytic permeable reactive barrier (e-barrier). In principle, an electrolytic approach to degrade aqueous energetic compounds such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) or 2,4,6-trinitrotoluene (TNT) can overcome limitations of management strategies that involve solely oxidation or reduction, through sequential oxidation-reduction or reduction-oxidation. The objective of this proof-of-concept research was to evaluate transformation of aqueous phase RDX and TNT in flow-through electrolytic reactors. Laboratory experiments were conducted using six identical column reactors containing porous media and expanded titanium-mixed-metal-oxide electrodes. Three columns tested TNT transformation and three tested RDXtransformation. Electrode sequence was varied between columns and one column for each contaminant acted as a no-voltage control. Over 97% of TNT and 93% of RDX was transformed in the reactors under sequential oxidation-reduction. Significant accumulation of known degradation intermediates was not observed under sequential oxidation-reduction. Removal of approximately 90% of TNT and 40% of RDX was observed under sequential reduction-oxidation. Power requirements on the order of 3 W/m2 were measured during the experiment. This suggests that an in-situ electrolytic approach may be cost-practical for managing groundwater contaminated with explosive compounds.

  17. Reduction of molybdenum oxide from steelmaking slags by pure liquid iron

    Directory of Open Access Journals (Sweden)

    Gao Y.M.

    2012-01-01

    Full Text Available The effects of reaction temperature, slag basicity and FeO concentration on the reduction of molybdenum oxide from steelmaking slags by pure liquid iron were investigated experimently. The reduction kinetics of molybdenum oxide by liquid iron was analysed. The reaction models were developed based on the condition that diffusion of [Mo] in liquid iron and CaMoO4 in slag is the control steps, respectively. These reaction models were tested using data from a series of experiments. The results indicate that under the present experimental conditions, the temperature and the FeO content, other than slag basicity, have some effects on the reduction of molybdenum oxide from steelmaking slags by pure liquid iron. Both the molybdenum oxide reduction rate and final reduction ratio increase with an increase of temperature and a decrease of FeO content. The diffusion of CaMoO4 in slag which dominated overall reduction process is the only one ratecontrolling step with its apparent activation energy 294 kJ/mol. The reduction of molybdenum oxide used directly as alloy additive can be further enhanced by strong stirring in the converter practice.

  18. Remote fabrication and irradiation test of recycled nuclear fuel prepared by the oxidation and reduction of spent oxide fuel

    Science.gov (United States)

    Jin Ryu, Ho; Chan Song, Kee; Il Park, Geun; Won Lee, Jung; Seung Yang, Myung

    2005-02-01

    A direct dry recycling process was developed in order to reuse spent pressurized light water reactor (LWR) nuclear fuel in CANDU reactors without the separation of sensitive nuclear materials such as plutonium. The benefits of the dry recycling process are the saving of uranium resources and the reduction of spent fuel accumulation as well as a higher proliferation resistance. In the process of direct dry recycling, fuel pellets separated from spent LWR fuel rods are oxidized from UO2 to U3O8 at 500 °C in an air atmosphere and reduced into UO2 at 700 °C in a hydrogen atmosphere, which is called OREOX (oxidation and reduction of oxide fuel). The pellets are pulverized during the oxidation and reduction processes due to the phase transformation between cubic UO2 and orthorhombic U3O8. Using the oxide powder prepared from the OREOX process, the compaction and sintering processes are performed in a remote manner in a shielded hot cell due to the high radioactivity of the spent fuel. Most of the fission gas and volatile fission products are removed during the OREOX and sintering processes. The mini-elements fabricated by the direct dry recycling process are irradiated in the HANARO research reactor for the performance evaluation of the recycled fuel pellets. Post-irradiation examination of the irradiated fuel showed that microstructural evolution and fission gas release behavior of the dry-recycled fuel were similar to high burnup UO2 fuel.

  19. Volatile organic compounds and oxides of nitrogen. Further emission reductions

    Energy Technology Data Exchange (ETDEWEB)

    Froste, H. [comp.

    1996-12-31

    This report presents the current status in relation to achievement of the Swedish Environmental target set by Parliament to reduce emission of volatile organic compounds by 50 per cent between 1988 and 2000. It also instructed the Agency to formulate proposed measures to achieve a 50 per cent reduction of emission of nitrogen oxides between 1985 and 2005. The report presents an overall account of emission trends for volatile organic compounds (from all sectors) and nitrogen oxides (from the industry sector) and steps proposed to achieve further emission reductions. 43 refs

  20. A superior method for the reduction of secondary phosphine oxides.

    Science.gov (United States)

    Busacca, Carl A; Lorenz, Jon C; Grinberg, Nelu; Haddad, Nizar; Hrapchak, Matt; Latli, Bachir; Lee, Heewon; Sabila, Paul; Saha, Anjan; Sarvestani, Max; Shen, Sherry; Varsolona, Richard; Wei, Xudong; Senanayake, Chris H

    2005-09-15

    [reaction: see text] Diisobutylaluminum hydride (DIBAL-H) and triisobutylaluminum have been found to be outstanding reductants for secondary phosphine oxides (SPOs). All classes of SPOs can be readily reduced, including diaryl, arylalkyl, and dialkyl members. Many SPOs can now be reduced at cryogenic temperatures, and conditions for preservation of reducible functional groups have been found. Even the most electron-rich and sterically hindered phosphine oxides can be reduced in a few hours at 50-70 degrees C. This new reduction has distinct advantages over existing technologies.

  1. Effect of copper dosing on sulfide inhibited reduction of nitric and nitrous oxide

    NARCIS (Netherlands)

    Manconi, I.; Maas, van der P.M.F.; Lens, P.N.L.

    2006-01-01

    The stimulating effect of copper addition on the reduction rate of nitrous oxide (N2O) to dinitrogen (N2) in the presence of sulfide was investigated in batch experiments (pH 7.0; 55 °C). N2O was dosed either directly as a gas to the headspace of the bottles or formed as intermediate during the deni

  2. Methanol Tolerant PWA-Pt/C Catalyst with Excellent Electrocatalytic Activity for Oxygen Reduction in Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    It was reported for the first time that phosphorictungstenic acid (PWA) could promote the oxygen reduction reaction (ORR) and inhibit the methanol oxidation reaction at the cathodic Pt/C catalyst in the direct methanol fuel cell (DMFC). When the weight ratio of PWA to Pt/C is 1,the composite catalyst increases the reduction current of oxygen by about 38% and decreases the oxidation current of methanol by about 76% compared with that of the Pt/C catalyst.

  3. Changes in physical properties of graphene oxide with thermal reduction

    Science.gov (United States)

    Pandit, Bhishma; Jo, Chang Hee; Joo, Kwan Seon; Cho, Jaehee

    2017-08-01

    Reduced graphene oxide (rGO) has attracted significant attention as an easily fabricable twodimensional material. Depending on the oxygen-containing functional groups (OFGs) in an rGO specimen, the optical and electrical properties can vary significantly, directly affecting the performance of devices in which rGO is implemented. Here, we investigated the optical and electrical properties of GO treated with various annealing (reduction) temperatures from 350 to 950 °C in H2 ambient. Using diverse characteristic tools, we found that the transmittance, nanoscale domain size, OFGs in GO and rGO, and Schottky barrier height (SBH) measured on n-type GaN are significantly influenced by the annealing temperature. The relative intensity of the defect-induced band in Raman spectroscopy showed a minimum at the annealing temperature of approximately 350 °C, before the OFGs in rGO showed vigorous changes in relative content. When the domain size of rGO reached a minimum at the annealing temperature of 650 °C, the SBH of rGO/GaN showed the maximum value of 1.07 eV.

  4. Methodology for the effective stabilization of tin-oxide-based oxidation/reduction catalysts

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Leighty, Bradley D. (Inventor); Watkins, Anthony N. (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor); Gulati, Suresh T. (Inventor); Summers, Jerry C. (Inventor)

    2011-01-01

    The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

  5. Oxidation-reduction potentials of different chlorophylls in methanol

    NARCIS (Netherlands)

    Goedheer, J.C.; Horreus de Haas, G.H.; Schuller, P.

    1958-01-01

    It was found that the reversible decolorisation of some chlorophylls upon the subsequent addition of ferric and ferrous salts, as originally measured by Rabinowtich and Weiss for chlorophyll a, proceeded at a reproducible oxidation-reduction potential. A marked difference was found to occur

  6. Simultaneous iridium catalysed oxidation and enzymatic reduction employing orthogonal reagents

    NARCIS (Netherlands)

    Mutti, Francesco G.; Orthaber, Andreas; Schrittwieser, Joerg H.; Vries, Johannes G. de; Pietschnig, Rudolf; Kroutil, Wolfgang

    2010-01-01

    An iridium catalysed oxidation was coupled concurrently to an asymmetric biocatalytic reduction in one-pot; thus it was shown for the first time that iridium- and alcohol dehydrogenase-catalysed redox reactions are compatible. As a model system racemic chlorohydrins were transformed to enantioenrich

  7. Oxidation-reduction potentials of different chlorophylls in methanol

    NARCIS (Netherlands)

    Goedheer, J.C.; Horreus de Haas, G.H.; Schuller, P.

    1958-01-01

    It was found that the reversible decolorisation of some chlorophylls upon the subsequent addition of ferric and ferrous salts, as originally measured by Rabinowtich and Weiss for chlorophyll a, proceeded at a reproducible oxidation-reduction potential. A marked difference was found to occur between

  8. Recent Progress in Direct Partial Oxidation of Methane to Methanol

    Institute of Scientific and Technical Information of China (English)

    Qijian Zhang; Dehua He; Qiming Zhu

    2003-01-01

    The direct conversion of methane to methanol has attracted a great deal of attention for nearly a century since it was first found possible in 1902, and it is still a challenging task. This review article describes recent advancements in the direct partial oxidation of methane to methanol. The history of direct oxidation of methane and the difficulties encountered in the partial oxidation of methane to methanol are briefly summarized. Recently reported developments in gas-phase homogeneous oxidation, heterogeneous catalytic oxidation and liquid phase homogeneous catalytic oxidation of methane are reviewed.

  9. Green reduction of graphene oxide via Lycium barbarum extract

    Science.gov (United States)

    Hou, Dandan; Liu, Qinfu; Cheng, Hongfei; Zhang, Hao; Wang, Sen

    2017-02-01

    The synthesis of graphene from graphene oxide (GO) usually involves toxic reducing agents that are harmful to human health and the environment. Here, we report a facile approach for effective reduction of GO, for the first time, using Lycium barbarum extract as a green and natural reducing agent. The morphology and de-oxidation efficiency of the reduced graphene were characterized and results showed that Lycium barbarum extract can effectively reduce GO into few layered graphene with a high carbon to oxygen ratio (6.5), comparable to that of GO reduced by hydrazine hydrate (6.6). The possible reduction mechanism of GO may be due to the active components existing in Lycium barbarum fruits, which have high binding affinity to the oxygen containing groups to form their corresponding oxides and other by-products. This method avoided the use of any nocuous chemicals, thus facilitating the mass production of graphene and graphene-based bio-materials.

  10. Optical endpoint detection for plasma reduction of graphene oxide

    Directory of Open Access Journals (Sweden)

    MaengJun Kim

    2013-03-01

    Full Text Available The plasma reduction process for the production of reduced graphene oxide (rGO requires precise process control in order to avoid the degradation of electrical characteristics. We report that the reduction status of the graphene oxides could be determined by monitoring the optical emission intensity at 844.6 nm. Properties of the rGO samples processed with various plasma exposure times were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, and 4-point probe measurements. Optimum electrical performance and surface morphology were obtained from the sample for which the reduction process was stopped when the emission intensity at 844.6 nm began to decrease.

  11. Unification of catalytic water oxidation and oxygen reduction reactions: amorphous beat crystalline cobalt iron oxides.

    Science.gov (United States)

    Indra, Arindam; Menezes, Prashanth W; Sahraie, Nastaran Ranjbar; Bergmann, Arno; Das, Chittaranjan; Tallarida, Massimo; Schmeißer, Dieter; Strasser, Peter; Driess, Matthias

    2014-12-17

    Catalytic water splitting to hydrogen and oxygen is considered as one of the convenient routes for the sustainable energy conversion. Bifunctional catalysts for the electrocatalytic oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are pivotal for the energy conversion and storage, and alternatively, the photochemical water oxidation in biomimetic fashion is also considered as the most useful way to convert solar energy into chemical energy. Here we present a facile solvothermal route to control the synthesis of amorphous and crystalline cobalt iron oxides by controlling the crystallinity of the materials with changing solvent and reaction time and further utilize these materials as multifunctional catalysts for the unification of photochemical and electrochemical water oxidation as well as for the oxygen reduction reaction. Notably, the amorphous cobalt iron oxide produces superior catalytic activity over the crystalline one under photochemical and electrochemical water oxidation and oxygen reduction conditions.

  12. Tyrosine can protect against oxidative stress through ferryl hemoglobin reduction.

    Science.gov (United States)

    Lu, Naihao; He, Yingjie; Chen, Chao; Tian, Rong; Xiao, Qiang; Peng, Yi-Yuan

    2014-08-01

    The toxic mechanism of hemoglobin (Hb) under oxidative stress is linked to the formations of highly cytotoxic ferryl species and subsequently heme-to-protein cross-linked derivative of Hb (Hb-X). In this study, we have examined the effects of free tyrosine and its analogues (3-chlorotyrosine, phenylalanine) on the stability of ferryl hemoglobin and the formation of Hb-X. The results showed that free tyrosine (not phenylalanine, 10-500 μM) was an efficient reducing agent of ferryl species and also effective at preventing the formation of cytotoxic Hb-X. Meanwhile, the dimeric tyrosine was formed as the oxidation product of tyrosine during Hb redox reaction. Compared with free tyrosine, 3-chlorotyrosine, an oxidation product of tyrosine and a proposed biomarker for hypochlorous acid (HOCl) in vivo, exhibited stronger antioxidant properties in Hb-induced oxidative stress, which was consistent with its more efficient ability in the reduction of ferryl species. These results showed that the presence of tyrosine and its derivative in vivo and vitro could ameliorate oxidative damage through ferryl heme reduction. The antioxidant ability, therefore, may provide new insights into the nutritional and physiological significance of free tyrosine with redox active heme proteins-related oxidative stress.

  13. Localized conductive patterning via focused electron beam reduction of graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Songkil; Henry, Mathias [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Kulkarni, Dhaval D.; Zackowski, Paul; Jang, Seung Soon; Tsukruk, Vladimir V. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Fedorov, Andrei G., E-mail: agf@gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2015-03-30

    We report on a method for “direct-write” conductive patterning via reduction of graphene oxide (GO) sheets using focused electron beam induced deposition (FEBID) of carbon. FEBID treatment of the intrinsically dielectric graphene oxide between two metal terminals opens up the conduction channel, thus enabling a unique capability for nanoscale conductive domain patterning in GO. An increase in FEBID electron dose results in a significant increase of the domain electrical conductivity with improving linearity of drain-source current vs. voltage dependence, indicative of a change of graphene oxide electronic properties from insulating to semiconducting. Density functional theory calculations suggest a possible mechanism underlying this experimentally observed phenomenon, as localized reduction of graphene oxide layers via interactions with highly reactive intermediates of electron-beam-assisted dissociation of surface-adsorbed hydrocarbon molecules. These findings establish an unusual route for using FEBID as nanoscale lithography and patterning technique for engineering carbon-based nanomaterials and devices with locally tailored electronic properties.

  14. NOx reduction by ozone injection and direct plasma treatment

    DEFF Research Database (Denmark)

    Stamate, Eugen; Salewski, Mirko

    2012-01-01

    NOx reduction by ozone injection and direct plasma treatment is investigated for different process parameters in a 6 m long serpentine reactor. Several aspects including the role of mixing scheme, water vapours, steep temperature gradient and time dependet NOx levels are taken into consideration....... The process chemistry is monitored by FTIR, chemiluminiscence and absorbtion spectroscopy. The kinetic mechanism is also investigated in 3D simulations....

  15. Biological reduction of graphene oxide using plant leaf extracts.

    Science.gov (United States)

    Lee, Geummi; Kim, Beom Soo

    2014-01-01

    Two-dimensional graphene has attracted significant attention due to its unique mechanical, electrical, thermal, and optical properties. Most commonly employed methods to chemically reduce graphene oxide to graphene use hydrazine or its derivatives as the reducing agent. However, they are highly hazardous and explosive. Various phytochemicals obtained from different natural sources such as leaves and peels of a plant are used as reducing agents in the preparation of different gold, silver, copper, and platinum nanoparticles. In this study, seven plant leaf extracts (Cherry, Magnolia, Platanus, Persimmon, Pine, Maple, and Ginkgo) were compared for their abilities to reduce graphene oxide. The optimized reaction conditions for the reduction of graphene oxide were determined as follows. Type of plant: Cherry (Prunus serrulata), reaction time: 12 h, composition of the reaction mixture: 16.7% v/v of plant leaf extract in total suspension, and temperature: 95°C. The degree of reduction caused by Cherry leaf extract was analyzed by elemental analysis and X-ray photoelectron spectroscopy. The reduction of graphene oxide was also confirmed by ultraviolet-visible spectroscopy, Fourier transform-infrared spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy, and thermogravimetric analysis.

  16. Selective insertion of sulfur dioxide reduction intermediates on graphene oxide.

    Science.gov (United States)

    Humeres, Eduardo; Debacher, Nito A; Smaniotto, Alessandra; de Castro, Karen M; Benetoli, Luís O B; de Souza, Eduardo P; Moreira, Regina de F P M; Lopes, Cristiane N; Schreiner, Wido H; Canle, Moisés; Santaballa, J Arturo

    2014-04-22

    Graphite microparticles (d50 6.20 μm) were oxidized by strong acids, and the resultant graphite oxide was thermally exfoliated to graphene oxide sheets (MPGO, C/O 1.53). Graphene oxide was treated with nonthermal plasma under a SO2 atmosphere at room temperature. The XPS spectrum showed that SO2 was inserted only as the oxidized intermediate at 168.7 eV in the S 2p region. Short thermal shocks at 600 and 400 °C, under an Ar atmosphere, produced reduced sulfur and carbon dioxide as shown by the XPS spectrum and TGA analysis coupled to FTIR. MPGO was also submitted to thermal reaction with SO2 at 630 °C, and the XPS spectrum in the S 2p region at 164.0 eV showed that this time only the nonoxidized episulfide intermediate was inserted. Plasma and thermal treatment produced a partial reduction of MPGO. The sequence of thermal reaction followed by plasma treatment inserted both sulfur intermediates. Because oxidized and nonoxidized intermediates have different reactivities, this selective insertion would allow the addition of selective types of organic fragments to the surface of graphene oxide.

  17. Self-assembled manganese oxide structures through direct oxidation

    KAUST Repository

    Zhao, Chao

    2012-12-01

    The morphology and phase of self-assembled manganese oxides during different stages of thermal oxidation were studied. Very interesting morphological patterns of Mn oxide films were observed. At the initial oxidation stage, the surface was characterized by the formation of ring-shaped patterns. As the oxidation proceeded to the intermediate stage, concentric plates formed to relax the compressive stress. Our experimental results gave a clear picture of the evolution of the structures. We also examined the properties of the structures. © 2012 Elsevier B.V.

  18. Recovery Of Nickel From Spent Nickel-Cadmium Batteries Using A Direct Reduction Process

    Directory of Open Access Journals (Sweden)

    Shin D.J.

    2015-06-01

    Full Text Available Most nickel is produced as Ferro-Nickel through a smelting process from Ni-bearing ore. However, these days, there have been some problems in nickel production due to exhaustion and the low-grade of Ni-bearing ore. Moreover, the smelting process results in a large amount of wastewater, slag and environmental risk. Therefore, in this research, spent Ni-Cd batteries were used as a base material instead of Ni-bearing ore for the recovery of Fe-Ni alloy through a direct reduction process. Spent Ni-Cd batteries contain 24wt% Ni, 18.5wt% Cd, 12.1% C and 27.5wt% polymers such as KOH. For pre-treatment, Cd was vaporized at 1024K. In order to evaluate the reduction conditions of nickel oxide and iron oxide, pre-treated spent Ni-Cd batteries were experimented on under various temperatures, gas-atmospheres and crucible materials. By a series of process, alloys containing 75 wt% Ni and 20 wt% Fe were produced. From the results, the reduction mechanism of nickel oxide and iron oxide were investigated.

  19. Contrasting effects of Al substitution on microbial reduction of Fe(III) (hydr)oxides

    Science.gov (United States)

    Ekstrom, Eileen B.; Learman, Deric R.; Madden, Andrew S.; Hansel, Colleen M.

    2010-12-01

    Aluminum, one of the most abundant elements in soils and sediments, is commonly found co-precipitated with Fe in natural Fe(III) (hydr)oxides; yet, little is known about how Al substitution impacts bacterial Fe(III) reduction. Accordingly, we investigated the reduction of Al substituted (0-13 mol% Al) goethite, lepidocrocite, and ferrihydrite by the model dissimilatory Fe(III)-reducing bacterium (DIRB), Shewanella putrefaciens CN32. Here we reveal that the impact of Al on microbial reduction varies with Fe(III) (hydr)oxide type. No significant difference in Fe(III) reduction was observed for either goethite or lepidocrocite as a function of Al substitution. In contrast, Fe(III) reduction rates significantly decreased with increasing Al substitution of ferrihydrite, with reduction rates of 13% Al-ferrihydrite more than 50% lower than pure ferrihydrite. Although Al substitution changed the minerals' surface area, particle size, structural disorder, and abiotic dissolution rates, we did not observe a direct correlation between any of these physiochemical properties and the trends in bacterial Fe(III) reduction. Based on projected Al-dependent Fe(III) reduction rates, reduction rates of ferrihydrite fall below those of lepidocrocite and goethite at substitution levels equal to or greater than 18 mol% Al. Given the prevalence of Al substitution in natural Fe(III) (hydr)oxides, our results bring into question the conventional assumptions about Fe (hydr)oxide bioavailability and suggest a more prominent role of natural lepidocrocite and goethite phases in impacting DIRB activity in soils and sediments.

  20. Metal-Free Reduction of Phosphine Oxides Using Polymethylhydrosiloxane

    Directory of Open Access Journals (Sweden)

    Emmanuel Nicolas

    2016-11-01

    Full Text Available A simple protocol is presented here for the use of inexpensive polymethylhydrosiloxane (PMHS, a waste product of the silicon industry, as stoichiometric reducing agent for phosphine oxides to phosphines, a highly desirable reaction to recover P-based ligands from their spent form. The reactions were studied by screening parameters, such as substrate to reductant ratio, temperature and reaction time, achieving good conversions and selectivities.

  1. Comparison of direct and indirect plasma oxidation of NO combined with oxidation by catalyst

    DEFF Research Database (Denmark)

    Jogi, Indrek; Stamate, Eugen; Irimiea, Cornelia

    2015-01-01

    Direct and indirect plasma oxidation of NOx was tested in a medium-scale test-bench at gas flows of 50 slm (3 m(3)/h). For direct plasma oxidation the synthetic flue gas was directed through a stacked DBD reactor. For indirect plasma oxidation, a DBD reactor was used to generate ozone from pure O-2...... of the DBD reactor decreased the long-term efficiency of direct plasma oxidation. At the same time, the efficiency of indirect oxidation increased at elevated reactor temperatures. Additional experiments were carried out to investigate the improvement of indirect oxidation by the introduction of catalyst...

  2. Reduction of secondary and tertiary phosphine oxides to phosphines.

    Science.gov (United States)

    Hérault, Damien; Nguyen, Duc Hanh; Nuel, Didier; Buono, Gérard

    2015-04-21

    Achiral or chiral phosphines are widely used in two main domains: ligands in organometallic catalysis and organocatalysis. For this reason, the obtention of optically pure phosphine has always been challenging in the development of asymmetric catalysis. The simplest method to obtain phosphines is the reduction of phosphine oxides. The essential difficulty is the strength of the P=O bond which involves new procedures to maintain a high chemio- and stereoselectivity. The reduction can occur with retention or inversion of the stereogenic phosphorus atom depending on the nature of the reducing agent and the presence of additives. In fact, the reactivity of the phosphine oxides and the mechanism of the reduction are not always well understood. Since the first work in the 1950's, numerous studies have been realised in order to develop methodologies with different reagents or to understand the mechanism of the reaction. In the last decade, efficient stereospecific methodologies have been developed to obtain optically pure tertiary phosphines from P-stereogenic phosphine oxides. In this review, we intend to provide a comprehensive and critical overview of these methodologies.

  3. Pathogenesis of Chronic Hyperglycemia: From Reductive Stress to Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Liang-Jun Yan

    2014-01-01

    Full Text Available Chronic overnutrition creates chronic hyperglycemia that can gradually induce insulin resistance and insulin secretion impairment. These disorders, if not intervened, will eventually be followed by appearance of frank diabetes. The mechanisms of this chronic pathogenic process are complex but have been suggested to involve production of reactive oxygen species (ROS and oxidative stress. In this review, I highlight evidence that reductive stress imposed by overflux of NADH through the mitochondrial electron transport chain is the source of oxidative stress, which is based on establishments that more NADH recycling by mitochondrial complex I leads to more electron leakage and thus more ROS production. The elevated levels of both NADH and ROS can inhibit and inactivate glyceraldehyde 3-phosphate dehydrogenase (GAPDH, respectively, resulting in blockage of the glycolytic pathway and accumulation of glycerol 3-phospate and its prior metabolites along the pathway. This accumulation then initiates all those alternative glucose metabolic pathways such as the polyol pathway and the advanced glycation pathways that otherwise are minor and insignificant under euglycemic conditions. Importantly, all these alternative pathways lead to ROS production, thus aggravating cellular oxidative stress. Therefore, reductive stress followed by oxidative stress comprises a major mechanism of hyperglycemia-induced metabolic syndrome.

  4. Recycling high density tungsten alloy powder by oxidization-reduction process

    Institute of Scientific and Technical Information of China (English)

    张兆森; 陈立宝; 贺跃辉; 黄伯云

    2002-01-01

    The processes of directly recycling high density tungsten alloy by oxidation-reduction technique were investigated. The particle size of recycled powder is fine, and the shape of powder particle is regular when the final reduction temperature is 850℃, in which the average size of the tungsten alloy particles reduced is about 1.5μm. The average size of the alloy particles increase to 6μm and 9μm when increasing the reduction temperature to 900℃ and 950℃, respectively. However, if the reduction temperature is higher than 900℃, the surface feature of powder is complicated. Increasing reduction temperature from 900℃ to 950℃, the content of oxygen of recycled powder decreases from 0.2314% to 0.1700%, and powder particles grow slightly. It has been also found that the chemical composition of the recycled alloy powder is the same as the initial powder.

  5. Hydrogen reduction of molybdenum oxide at room temperature

    Science.gov (United States)

    Borgschulte, Andreas; Sambalova, Olga; Delmelle, Renaud; Jenatsch, Sandra; Hany, Roland; Nüesch, Frank

    2017-01-01

    The color changes in chemo- and photochromic MoO3 used in sensors and in organic photovoltaic (OPV) cells can be traced back to intercalated hydrogen atoms stemming either from gaseous hydrogen dissociated at catalytic surfaces or from photocatalytically split water. In applications, the reversibility of the process is of utmost importance, and deterioration of the layer functionality due to side reactions is a critical challenge. Using the membrane approach for high-pressure XPS, we are able to follow the hydrogen reduction of MoO3 thin films using atomic hydrogen in a water free environment. Hydrogen intercalates into MoO3 forming HxMoO3, which slowly decomposes into MoO2 +1/2 H2O as evidenced by the fast reduction of Mo6+ into Mo5+ states and slow but simultaneous formation of Mo4+ states. We measure the decrease in oxygen/metal ratio in the thin film explaining the limited reversibility of hydrogen sensors based on transition metal oxides. The results also enlighten the recent debate on the mechanism of the high temperature hydrogen reduction of bulk molybdenum oxide. The specific mechanism is a result of the balance between the reduction by hydrogen and water formation, desorption of water as well as nucleation and growth of new phases.

  6. In situ Reduction and Oxidation of Nickel from Solid Oxide Fuel Cells in a Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Faes, Antonin; Jeangros, Quentin; Wagner, Jakob Birkedal;

    2009-01-01

    , then moves to the center of the NiO grain. At higher temperature the reduction occurs also at the free NiO surface and the NiO/NiO grain boundaries. The growth of Ni is epitaxial on its oxide. Due to high volume decrease, nanopores are formed during reduction. During oxidation, oxide nanocrystallites......Environmental transmission electron microscopy was used to characterize in situ the reduction and oxidation of nickel from a Ni/YSZ solid oxide fuel cell anode support between 300-500{degree sign}C. The reduction is done under low hydrogen pressure. The reduction initiates at the NiO/YSZ interface...

  7. Nanoscale reduction of graphene oxide thin films and its characterization

    KAUST Repository

    Lorenzoni, M.

    2015-06-29

    In this paper, we report on a method to reduce thin films of graphene oxide (GO) to a spatial resolution better than 100 nm over several tens of micrometers by means of an electrochemical scanning probe based lithography. In situ tip-current measurements show that an edged drop in electrical resistance characterizes the reduced areas, and that the reduction process is, to a good approximation, proportional to the applied bias between the onset voltage and the saturation thresholds. An atomic force microscope (AFM) quantifies the drop of the surface height for the reduced profile due to the loss of oxygen. Complementarily, lateral force microscopy reveals a homogeneous friction coefficient of the reduced regions that is remarkably lower than that of native graphene oxide, confirming a chemical change in the patterned region. Micro Raman spectroscopy, which provides access to insights into the chemical process, allows one to quantify the restoration and de-oxidation of the graphitic network driven by the electrochemical reduction and to determine characteristic length scales. It also confirms the homogeneity of the process over wide areas. The results shown were obtained from accurate analysis of the shift, intensity and width of Raman peaks for the main vibrational bands of GO and reduced graphene oxide (rGO) mapped over large areas. Concerning multilayered GO thin films obtained by drop-casting we have demonstrated an unprecedented lateral resolution in ambient conditions as well as an improved control, characterization and understanding of the reduction process occurring in GO randomly folded multilayers, useful for large-scale processing of graphene-based material. © 2015 IOP Publishing Ltd.

  8. Direct synthesis of graphene nanosheets support Pd nanodendrites for electrocatalytic formic acid oxidation

    Science.gov (United States)

    Yang, Su-Dong; Chen, Lin

    2015-11-01

    We report a solvothermal method preparation of dendritic Pd nanoparticles (DPNs) and spherical Pd nanoparticles (SPNs) supported on reduced graphene oxide (RGO). Drastically different morphologies of Pd NPs with nanodendritic structures or spherical structures were observed on graphene by controlling the reduction degree of graphene oxide (GO) under mild conditions. In addition to being a commonplace substrate, GO plays a more important role that relies on its surface groups, which serves as a shape-directing agent to direct the dendritic growth. As a result, the obtained DPNs/RGO catalyst exhibits a significantly enhanced electro-catalytic behavior for the oxidation of formic acid compared to the SPNs/RGO catalyst.

  9. Development of Linear Irreversible Thermodynamic Model for Oxidation Reduction Potential in Environmental Microbial System

    Science.gov (United States)

    Cheng, Hong-Bang; Kumar, Mathava; Lin, Jih-Gaw

    2007-01-01

    Nernst equation has been directly used to formulate the oxidation reduction potential (ORP) of reversible thermodynamic conditions but applied to irreversible conditions after several assumptions and/or modifications. However, the assumptions are sometimes inappropriate in the quantification of ORP in nonequilibrium system. We propose a linear nonequilibrium thermodynamic model, called microbial related reduction and oxidation reaction (MIRROR Model No. 1) for the interpretation of ORP in biological process. The ORP was related to the affinities of catabolism and anabolism. The energy expenditure of catabolism and anabolism was directly proportional to overpotential (η), straight coefficient of electrode (LEE), and degree of coupling between catabolism and ORP electrode, respectively. Finally, the limitations of MIRROR Model No. 1 were discussed for expanding the applicability of the model. PMID:17496027

  10. Catalysis of Reduction and Oxidation Reactions for Application in Gas Particle Filters

    Energy Technology Data Exchange (ETDEWEB)

    Udron, L.; Turek, T.

    2002-09-19

    The present study is a first part of an investigation addressing the simultaneous occurrence of oxidation and reduction reactions in catalytic filters. It has the objectives (a) to assess the state of knowledge regarding suitable (types of) catalysts for reduction and oxidation, (b) to collect and analyze published information about reaction rates of both NOx reduction and VOC oxidation, and (c) to adjust a lab-scale screening method to the requirements of an activity test with various oxidation/reduction catalysts.

  11. Water as a Direct Hydrogen Donor in Supercritical Carbon Di-oxide: A Novel and Efficient Zn-H2O-CO2 System for Chemo selective Reduction of Nitrobenzenes to Anilines

    Institute of Scientific and Technical Information of China (English)

    JIANG Huan-Feng; DONG Yao-Sen

    2008-01-01

    An eco-friendly and cheap Zn-H2O-CO2 system was presented for chemoselective reduction of nitrobenzenes to anilines with high yields (80%-97% isolated yields) in supercritical carbon dioxide. This process brings together the very important green chemistry technologies--the use of carbon dioxide as a solvent and the use of water as a hydrogen donor.

  12. Nanomaterial resistant microorganism mediated reduction of graphene oxide.

    Science.gov (United States)

    Chouhan, Raghuraj S; Pandey, Ashish; Qureshi, Anjum; Ozguz, Volkan; Niazi, Javed H

    2016-10-01

    In this study, soil bacteria were isolated from nanomaterials (NMs) contaminated pond soil and enriched in the presence of graphene oxide (GO) in mineral medium to obtain NMs resistant bacteria. The isolated resistant bacteria were biochemically and genetically identified as Fontibacillus aquaticus. The resistant bacteria were allowed to interact with engineered GO in order to study the biotransformation in GO structure. Raman spectra of GO extracted from culture medium revealed decreased intensity ratio of ID/IG with subsequent reduction of CO which was consistent with Fourier transform infrared (FTIR) results. The structural changes and exfoliatied GO nanosheets were also evident from transmission electron microscopy (TEM) images. Ultraviolet-visible spectroscopy, high resolution X-ray diffraction (XRD) and current-voltage measurements confirmed the reduction of GO after the interaction with resistant bacteria. X-ray photoelectron spectroscopy (XPS) analysis of biotransformed GO revealed reduction of oxygen-containing species on the surface of nanosheets. Our results demonstrated that the presented method is an environment friendly, cost effective, simple and based on green approaches for the reduction of GO using NMs resistant bacteria.

  13. PREPARATION OF WC-Co POWDER BY DIRECT REDUCTION AND CARBONIZATION

    Institute of Scientific and Technical Information of China (English)

    Zhonglai Yi; Gangqin Shao; Xinglong Duan; Peng Sun; Xiaoliang Shi; Zhen Xiong; Jingkun Guo

    2005-01-01

    A new approach to produce superfine WC-Co powder by direct reduction and carbonization is proposed.Water-soluble salts containing W and Co were used as raw materials. Tungsten and cobalt oxide powder (CoWO4/WO3)was first formed by a spray-pyrolysis technique, which was then mixed with carbon black and converted to WC-Co composite powder at 950℃ for 4 h in N2 atmosphere. The resulting powder has a particle size of 100-300 nm.

  14. Simultaneous reductive dissolution of iron oxide and oxidation of iodide in ice.

    Science.gov (United States)

    Kim, Kitae; Choi, Wonyong

    2015-04-01

    Iron is an important trace element controlling the metabolism and growth of all kinds of living species. Especially, the bio-availability of iron has been regarded as the limiting factor for primary productivity in HNLC (High Nutrients Low Chlorophyll) regions including Southern ocean. The dissolution of iron oxide provides enhanced the bio-availability of iron for phytoplankton growth. The halogen chemistry in polar regions is related to various important environmental processes such as Antarctic Ozone Depletion Event(ODE), mercury depletion, oxidative processes in atmosphere, and the formation of CCN (Cloud Condensation Nuclei). In this study, we investigated the reductive dissolution of iron oxide particles to produce Fe(II)aq and simultaneous oxidation of I- (iodide) to I3- (tri-iodide) in ice phase under UV irradiation or dark condition. The reductive generation of Fe(II)aq from iron oxides and oxidation of iodide to I3- were negligible in water but significantly accelerated in frozen solution both in the presence and absence of light. The enhanced reductive generation of Fe(II)aq and oxidative formation of I3- in ice were observed regardless of the various types of iron oxides [hematite (α-Fe2O3) maghemite (γ- Fe2O3), goethite (α-FeOOH), lepidocrocite (γ-FeOOH) and, magnetite (Fe3O4)]. We explained that the enhanced redox production of Fe(II)aq and I3- in ice is contributed to the freeze concentration of iodides, protons, and dissolved oxygen in the unfrozen solution. When the concentration of both iodides and protons were raised by 10-fold each, the formation of Fe(II)aq in water under UV irradiation was approached to those in ice. The outdoor experiments were carried out under ambient solar radiation in winter season of mid-latitude (Pohang, Korea: 36°N latitude) and also confirmed that the production of Fe(II)aq via reductive dissolution of iron oxide and I3- generation via I- oxidation were enhanced in frozen solution. These results suggest that iron

  15. The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part II. The reduction of iron oxide/carbon composites

    Science.gov (United States)

    Sohn, I.; Fruehan, R. J.

    2006-04-01

    The reduction of iron oxide/carbon composite pellets with hydrogen at 900 °C to 1000 °C was studied. Compared to hydrogen, the reduction by carbon was negligible at 900 °C and below. However, significant carbon oxidation of the iron oxide/graphite pellets by H2O generated from the reduction of Fe2O3 by H2 was observed. At higher temperatures, reduction by carbon complicates the overall reduction mechanism, with the iron oxide/graphite composite pellet found to be more reactive than the iron oxide/char composite pellet. From the scanning electron micrographs, partially reduced composite pellets showed a typical topochemical interface with an intermediate region between an oxygen-rich unreacted core and an iron-rich outer shell. To determine the possibility of reduction by volatiles, a layer of iron oxide powders was spread on top of a high volatile containing bituminous coal and heated inside a reactor using infra-red radiation. By separating the individual reactions involved for an iron oxide/coal mixture where a complex set of reactions occur simultaneously, it was possible to determine the sole effect of volatile reduction. It was found that the light reducing gases evolve initially and react with the iron oxide, with complex hydrocarbons evolving at the later stages. The volatiles caused about 20 to 50 pct reduction of the iron oxide.

  16. Complexation facilitated reduction of aromatic N-oxides by aqueous Fe(II)-tiron complex: reaction kinetics and mechanisms.

    Science.gov (United States)

    Chen, Yiling; Zhang, Huichun

    2013-10-01

    Rapid reduction of carbadox (CDX), olaquindox and several other aromatic N-oxides were investigated in aqueous solution containing Fe(II) and tiron. Consistent with previous work, the 1:2 Fe(II)-tiron complex, FeL2(6-), is the dominant reactive species as its concentration linearly correlates with the observed rate constant kobs under various conditions. The N-oxides without any side chains were much less reactive, suggesting direct reduction of the N-oxides is slow. UV-vis spectra suggest FeL2(6-) likely forms 5- or 7-membered rings with CDX and olaquindox through the N and O atoms on the side chain. The formed inner-sphere complexes significantly facilitated electron transfer from FeL2(6-) to the N-oxides. Reduction products of the N-oxides were identified by HPLC/QToF-MS to be the deoxygenated analogs. QSAR analysis indicated neither the first electron transfer nor N-O bond cleavage is the rate-limiting step. Calculations of the atomic spin densities of the anionic N-oxides confirmed the extensive delocalization between the aromatic ring and the side chain, suggesting complex formation can significantly affect the reduction kinetics. Our results suggest the complexation facilitated N-oxide reduction by Fe(II)-tiron involves a free radical mechanism, and the subsequent deoxygenation might also benefit from the weak complexation of Fe(II) with the N-oxide O atom.

  17. Coupling carbon dioxide reduction with water oxidation in nanoscale photocatalytic assemblies.

    Science.gov (United States)

    Kim, Wooyul; McClure, Beth Anne; Edri, Eran; Frei, Heinz

    2016-06-07

    The reduction of carbon dioxide by water with sunlight in an artificial system offers an opportunity for utilizing non-arable land for generating renewable transportation fuels to replace fossil resources. Because of the very large scale required for the impact on fuel consumption, the scalability of artificial photosystems is of key importance. Closing the photosynthetic cycle of carbon dioxide reduction and water oxidation on the nanoscale addresses major barriers for scalability as well as high efficiency, such as resistance losses inherent to ion transport over macroscale distances, loss of charge and other efficiency degrading processes, or excessive need for the balance of system components, to mention a few. For the conversion of carbon dioxide to six-electron or even more highly reduced liquid fuel products, introduction of a proton conducting, gas impermeable separation membrane is critical. This article reviews recent progress in the development of light absorber-catalyst assemblies for the reduction and oxidation half reactions with focus on well defined polynuclear structures, and on novel approaches for optimizing electron transfer among the molecular or nanoparticulate components. Studies by time-resolved optical and infrared spectroscopy for the understanding of charge transfer processes between the chromophore and the catalyst, and of the mechanism of water oxidation at metal oxide nanocatalysts through direct observation of surface reaction intermediates are discussed. All-inorganic polynuclear units for reducing carbon dioxide by water at the nanoscale are introduced, and progress towards core-shell nanotube assemblies for completing the photosynthetic cycle under membrane separation is described.

  18. Nitrous oxide emission reduction in temperate biochar-amended soils

    Science.gov (United States)

    Felber, R.; Hüppi, R.; Leifeld, J.; Neftel, A.

    2012-01-01

    Biochar, a pyrolysis product of organic residues, is an amendment for agricultural soils to improve soil fertility, sequester CO2 and reduce greenhouse gas (GHG) emissions. In highly weathered tropical soils laboratory incubations of soil-biochar mixtures revealed substantial reductions for nitrous oxide (N2O) and carbon dioxide (CO2). In contrast, evidence is scarce for temperate soils. In a three-factorial laboratory incubation experiment two different temperate agricultural soils were amended with green waste and coffee grounds biochar. N2O and CO2 emissions were measured at the beginning and end of a three month incubation. The experiments were conducted under three different conditions (no additional nutrients, glucose addition, and nitrate and glucose addition) representing different field conditions. We found mean N2O emission reductions of 60 % compared to soils without addition of biochar. The reduction depended on biochar type and soil type as well as on the age of the samples. CO2 emissions were slightly reduced, too. NO3- but not NH4+ concentrations were significantly reduced shortly after biochar incorporation. Despite the highly significant suppression of N2O emissions biochar effects should not be transferred one-to-one to field conditions but need to be tested accordingly.

  19. Nitrous oxide emission reduction in temperate biochar-amended soils

    Directory of Open Access Journals (Sweden)

    R. Felber

    2012-01-01

    Full Text Available Biochar, a pyrolysis product of organic residues, is an amendment for agricultural soils to improve soil fertility, sequester CO2 and reduce greenhouse gas (GHG emissions. In highly weathered tropical soils laboratory incubations of soil-biochar mixtures revealed substantial reductions for nitrous oxide (N2O and carbon dioxide (CO2. In contrast, evidence is scarce for temperate soils. In a three-factorial laboratory incubation experiment two different temperate agricultural soils were amended with green waste and coffee grounds biochar. N2O and CO2 emissions were measured at the beginning and end of a three month incubation. The experiments were conducted under three different conditions (no additional nutrients, glucose addition, and nitrate and glucose addition representing different field conditions. We found mean N2O emission reductions of 60 % compared to soils without addition of biochar. The reduction depended on biochar type and soil type as well as on the age of the samples. CO2 emissions were slightly reduced, too. NO3 but not NH4+ concentrations were significantly reduced shortly after biochar incorporation. Despite the highly significant suppression of N2O emissions biochar effects should not be transferred one-to-one to field conditions but need to be tested accordingly.

  20. Direct and Indirect Phototransformation of Graphene Oxide in Sunlight

    Science.gov (United States)

    Direct and indirect (with added H202 that serves as OH precursor) photoreactions of grapheme oxide (GO) were examined under sunlight exposure. The results indicate that GO photoreacts under both conditions, leading to significant alterations in GO's physicochemical properties. In...

  1. Reduction in oxidatively generated DNA damage following smoking cessation

    Directory of Open Access Journals (Sweden)

    Freund Harold G

    2011-05-01

    Full Text Available Abstract Background Cigarette smoking is a known cause of cancer, and cancer may be in part due to effects of oxidative stress. However, whether smoking cessation reverses oxidatively induced DNA damage unclear. The current study sought to examine the extent to which three DNA lesions showed significant reductions after participants quit smoking. Methods Participants (n = 19 in this study were recruited from an ongoing 16-week smoking cessation clinical trial and provided blood samples from which leukocyte DNA was extracted and assessed for 3 DNA lesions (thymine glycol modification [d(TgpA]; formamide breakdown of pyrimidine bases [d(TgpA]; 8-oxo-7,8-dihydroguanine [d(Gh] via liquid chromatography tandem mass spectrometry (LC-MS/MS. Change in lesions over time was assessed using generalized estimating equations, controlling for gender, age, and treatment condition. Results Overall time effects for the d(TgpA (χ2(3 = 8.068, p fpA (χ2(3 = 8.477, p h (χ2(3 = 37.599, p gpA and d(PfpA lesions show relatively greater rebound at Week 16 compared to the d(Gh lesion (88% of baseline for d(TgpA, 64% of baseline for d(PfpA, vs 46% of baseline for d(Gh. Conclusions Overall, results from this analysis suggest that cigarette smoking contributes to oxidatively induced DNA damage, and that smoking cessation appears to reduce levels of specific damage markers between 30-50 percent in the short term. Future research may shed light on the broader array of oxidative damage influenced by smoking and over longer durations of abstinence, to provide further insights into mechanisms underlying carcinogenesis.

  2. Molecular Underpinnings of Fe(III) Oxide Reduction by Shewanella Oneidensis MR-1

    Science.gov (United States)

    Shi, Liang; Rosso, Kevin M.; Clarke, Tomas A.; Richardson, David J.; Zachara, John M.; Fredrickson, James K.

    2012-01-01

    In the absence of O2 and other electron acceptors, the Gram-negative bacterium Shewanella oneidensis MR-1 can use ferric [Fe(III)] (oxy)(hydr)oxide minerals as the terminal electron acceptors for anaerobic respiration. At circumneutral pH and in the absence of strong complexing ligands, Fe(III) oxides are relatively insoluble and thus are external to the bacterial cells. S. oneidensis MR-1 and related strains of metal-reducing Shewanella have evolved machinery (i.e., metal-reducing or Mtr pathway) for transferring electrons from the inner-membrane, through the periplasm and across the outer-membrane to the surface of extracellular Fe(III) oxides. The protein components identified to date for the Mtr pathway include CymA, MtrA, MtrB, MtrC, and OmcA. CymA is an inner-membrane tetraheme c-type cytochrome (c-Cyt) that belongs to the NapC/NrfH family of quinol dehydrogenases. It is proposed that CymA oxidizes the quinol in the inner-membrane and transfers the released electrons to MtrA either directly or indirectly through other periplasmic proteins. A decaheme c-Cyt, MtrA is thought to be embedded in the trans outer-membrane and porin-like protein MtrB. Together, MtrAB deliver the electrons through the outer-membrane to the MtrC and OmcA on the outmost bacterial surface. MtrC and OmcA are the outer-membrane decaheme c-Cyts that are translocated across the outer-membrane by the bacterial type II secretion system. Functioning as terminal reductases, MtrC and OmcA can bind the surface of Fe(III) oxides and transfer electrons directly to these minerals via their solvent-exposed hemes. To increase their reaction rates, MtrC and OmcA can use the flavins secreted by S. oneidensis MR-1 cells as diffusible co-factors for reduction of Fe(III) oxides. Because of their extracellular location and broad redox potentials, MtrC and OmcA can also serve as the terminal reductases for soluble forms of Fe(III). In addition to Fe(III) oxides, Mtr pathway is also involved in reduction of

  3. Selected constants oxidation-reduction potentials of inorganic substances in aqueous solution

    CERN Document Server

    Charlot, G; Marchon, M J C

    2013-01-01

    Selected Constants: Oxidation-reduction Potentials of Inorganic Substances in Aqueous Solution presents tables that will aid chemists in finding the best or most probable value of the normal or formal oxidation-reduction potential of oxidation-reduction systems. The book first presents numerical calculations that show the degree of oxidation and real oxidation-reduction systems, including the value of the potential, temperature, nature and composition of the medium, and the method of determination used. The text then takes a look at the choice of data, as well as intensity/potential curves an

  4. Catalyst and method for reduction of nitrogen oxides

    Science.gov (United States)

    Ott, Kevin C.

    2008-05-27

    A Selective Catalytic Reduction (SCR) catalyst was prepared by slurry coating ZSM-5 zeolite onto a cordierite monolith, then subliming an iron salt onto the zeolite, calcining the monolith, and then dipping the monolith either into an aqueous solution of manganese nitrate and cerium nitrate and then calcining, or by similar treatment with separate solutions of manganese nitrate and cerium nitrate. The supported catalyst containing iron, manganese, and cerium showed 80 percent conversion at 113 degrees Celsius of a feed gas containing nitrogen oxides having 4 parts NO to one part NO.sub.2, about one equivalent ammonia, and excess oxygen; conversion improved to 94 percent at 147 degrees Celsius. N.sub.2O was not detected (detection limit: 0.6 percent N.sub.2O).

  5. Wilder Bancroft's Study of Oxidant-Reductant Cells

    Science.gov (United States)

    Stock, John T.

    1998-07-01

    Wilder Dwight Bancroft (1867 -1953), a Harvard graduate, entered Ostwald's Leipzig laboratory in 1890. Bancroft made a systematic study of potentiometric cells in which one half contained an oxidant solution, the other half a reductant solution. He stressed the importance of the equilibration of the platinum electrodes, examined the effects of acidity and of concentration on the emf of a cell, and demonstrated that this emf was the algebraic sum of the potentials of the half-cells. After receipt of his Ph.D. in 1892, Bancroft continued his potentiometric studies in Amsterdam. Following a brief return to Harvard, Bancroft moved to Cornell, and remained there until his retirement in 1937. He founded and edited the Journal of Physical Chemistry, and was President of the American Chemical Society in 1910. He was also twice President of the Electrochemical Society.

  6. Monte Carlo radiative transfer simulation of a cavity solar reactor for the reduction of cerium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Villafan-Vidales, H.I.; Arancibia-Bulnes, C.A.; Dehesa-Carrasco, U. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Col. Centro, A.P. 34, Temixco, Morelos 62580 (Mexico); Romero-Paredes, H. [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No.186, Col. Vicentina, A.P. 55-534, Mexico D.F 09340 (Mexico)

    2009-01-15

    Radiative heat transfer in a solar thermochemical reactor for the thermal reduction of cerium oxide is simulated with the Monte Carlo method. The directional characteristics and the power distribution of the concentrated solar radiation that enters the cavity is obtained by carrying out a Monte Carlo ray tracing of a paraboloidal concentrator. It is considered that the reactor contains a gas/particle suspension directly exposed to concentrated solar radiation. The suspension is treated as a non-isothermal, non-gray, absorbing, emitting, and anisotropically scattering medium. The transport coefficients of the particles are obtained from Mie-scattering theory by using the optical properties of cerium oxide. From the simulations, the aperture radius and the particle concentration were optimized to match the characteristics of the considered concentrator. (author)

  7. Low Temperature Selective Catalytic Reduction of Nitrogen Oxides in Production of Nitric Acid by the Use of Liquid

    Directory of Open Access Journals (Sweden)

    Kabljanac, Ž.

    2011-11-01

    Full Text Available This paper presents the application of low-temperature selective catalytic reduction of nitrous oxides in the tail gas of the dual-pressure process of nitric acid production. The process of selective catalytic reduction is carried out using the TiO2/WO3 heterogeneous catalyst applied on a ceramic honeycomb structure with a high geometric surface area per volume. The process design parameters for nitric acid production by the dual-pressure procedure in a capacity range from 75 to 100 % in comparison with designed capacity for one production line is shown in the Table 1. Shown is the effectiveness of selective catalytic reduction in the temperature range of the tail gas from 180 to 230 °C with direct application of liquid ammonia, without prior evaporation to gaseous state. The results of inlet and outlet concentrations of nitrous oxides in the tail gas of the nitric acid production process are shown in Figures 1 and 2. Figure 3 shows the temperature dependence of the selective catalytic reduction of nitrous oxides expressed as NO2in the tail gas of nitric acid production with the application of a constant mass flow of liquid ammonia of 13,0 kg h-1 and average inlet mass concentration of the nitrous oxides expressed as NO2of 800,0 mgm-3 during 100 % production capacity. The specially designed liquid-ammonia direct-dosing system along with the effective homogenization of the tail gas resulted in emission levels of nitrous oxides expressed as NO2 in tail gas ranging from 100,0 to 185,0 mg m-3. The applied low-temperature selective catalytic reduction of the nitrous oxides in the tail gases by direct use of liquid ammonia is shown in Figure 4. It is shown that low-temperature selective catalytic reduction with direct application of liquid ammonia opens a new opportunity in the reduction of nitrous oxide emissions during nitric acid production without the risk of dangerous ammonium nitrate occurring in the process of subsequent energy utilization of

  8. Underpotential deposition of Li in a molten LiCl-Li{sub 2}O electrolyte for the electrochemical reduction of U from uranium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Jin-Mok; Jeong, Sang Mun; Lee, Hansoo [Korea Atomic Energy Research Institute, Daejeon, 305-353 (Korea)

    2010-05-15

    Reactive metal oxides are conventionally reduced to metal by metallothermic reduction. This paper presents on the efficient reduction method based on the electrochemical reaction in a molten LiCl-Li{sub 2}O electrolyte at 650 C. An underpotential deposition of Li on uranium oxides was observed that enabled the mass electrochemical reduction of U{sub 3}O{sub 8} to U. An advantage of using in-situ generated Li as a reductant is that a high-speed electrochemical reduction could be achieved with a wider operating voltage window when compared to a direct electrochemical reduction. (author)

  9. Linking methane oxidation with perchlorate reduction: a microbial base for possible Martian life

    Science.gov (United States)

    Miller, L. G.; Carlstrom, C.; Baesman, S. M.; Coates, J. D.; Oremland, R. S.

    2011-12-01

    Recent observations of methane (CH4) and perchlorate (ClO4-) within the atmosphere and surface of Mars, respectively, provide impetus for establishing a metabolic linkage between these compounds whereby CH4 acts as an electron donor and perchlorate acts as an electron acceptor. Direct linkage through anaerobic oxidation of methane (AOM) has not been observed. However, indirect syntrophic oxygenase-dependent oxidation of CH4 with an aerobic methane oxidizer is feasible. The pathway for anaerobic dissimilatory perchlorate reduction includes 3 steps. The first 2 are sequential reductions of (1) perchlorate to chlorate and (2) chlorate to chlorite, mediated by perchlorate reductase. The third step is disproportionation of chlorite to chloride and molecular oxygen, mediated by chlorite dismutase. Utilization of thusly derived oxygen by hydrocarbon-degrading organisms in anoxic environments was first demonstrated by Coates et. al. (1998)1, however the link to aerobic methane oxidation was not examined at that time. Here, we systematically explore the potential for several species of aerobic methanotrophs to couple with chlorite during dissimilatory perchlorate reduction. In one experiment, 0.5 kPa CH4 was completely removed in one day from the headspace of combined cell suspensions of Dechloromonas agitata strain CKB and Methylococcus capsulatus in the presence of 5 mM chlorite. Oxidation of labeled 14CH4 to 14CO2 under similar conditions was later confirmed. Another experiment demonstrated complete removal of 0.2 kPa CH4 over several days by Methylobacter albus strain BG8 with strain CKB in the presence of 5 mM chlorite. Finally, we observed complete removal of 0.2 kPa CH4 in bottles containing natural soil (enriched in methanotrophs by CH4 additions over several weeks) and strain CKB and in the presence of 10 mM chlorite. This soil, collected from a pristine lake shoreline, demonstrated endogenous methane, perchlorate, chlorate and chlorite uptake. Other soil and

  10. Assessment of Eccentric Exercise-Induced Oxidative Stress Using Oxidation-Reduction Potential Markers

    Directory of Open Access Journals (Sweden)

    Dimitrios Stagos

    2015-01-01

    Full Text Available The aim of the present study was to investigate the use of static (sORP and capacity ORP (cORP oxidation-reduction potential markers as measured by the RedoxSYS Diagnostic System in plasma, for assessing eccentric exercise-induced oxidative stress. Nineteen volunteers performed eccentric exercise with the knee extensors. Blood was collected before, immediately after exercise, and 24, 48, and 72 h after exercise. Moreover, common redox biomarkers were measured, which were protein carbonyls, thiobarbituric acid-reactive substances, total antioxidant capacity in plasma, and catalase activity and glutathione levels in erythrocytes. When the participants were examined as one group, there were not significant differences in any marker after exercise. However, in 11 participants there was a high increase in cORP after exercise, while in 8 participants there was a high decrease. Thus, the participants were divided in low cORP group exhibiting significant decrease in cORP after exercise and in high cORP group exhibiting significant increase. Moreover, only in the low cORP group there was a significant increase in lipid peroxidation after exercise suggesting induction of oxidative stress. The results suggested that high decreases in cORP values after exercise may indicate induction of oxidative stress by eccentric exercise, while high increases in cORP values after exercise may indicate no existence of oxidative stress.

  11. Assessment of eccentric exercise-induced oxidative stress using oxidation-reduction potential markers.

    Science.gov (United States)

    Stagos, Dimitrios; Goutzourelas, Nikolaos; Ntontou, Amalia-Maria; Kafantaris, Ioannis; Deli, Chariklia K; Poulios, Athanasios; Jamurtas, Athanasios Z; Bar-Or, David; Kouretas, Dimitrios

    2015-01-01

    The aim of the present study was to investigate the use of static (sORP) and capacity ORP (cORP) oxidation-reduction potential markers as measured by the RedoxSYS Diagnostic System in plasma, for assessing eccentric exercise-induced oxidative stress. Nineteen volunteers performed eccentric exercise with the knee extensors. Blood was collected before, immediately after exercise, and 24, 48, and 72 h after exercise. Moreover, common redox biomarkers were measured, which were protein carbonyls, thiobarbituric acid-reactive substances, total antioxidant capacity in plasma, and catalase activity and glutathione levels in erythrocytes. When the participants were examined as one group, there were not significant differences in any marker after exercise. However, in 11 participants there was a high increase in cORP after exercise, while in 8 participants there was a high decrease. Thus, the participants were divided in low cORP group exhibiting significant decrease in cORP after exercise and in high cORP group exhibiting significant increase. Moreover, only in the low cORP group there was a significant increase in lipid peroxidation after exercise suggesting induction of oxidative stress. The results suggested that high decreases in cORP values after exercise may indicate induction of oxidative stress by eccentric exercise, while high increases in cORP values after exercise may indicate no existence of oxidative stress.

  12. Reduced Graphene Oxides: Influence of the Reduction Method on the Electrocatalytic Effect towards Nucleic Acid Oxidation

    Science.gov (United States)

    Báez, Daniela F.; Pardo, Helena; Laborda, Ignacio; Marco, José F.; Yáñez, Claudia; Bollo, Soledad

    2017-01-01

    For the first time a critical analysis of the influence that four different graphene oxide reduction methods have on the electrochemical properties of the resulting reduced graphene oxides (RGOs) is reported. Starting from the same graphene oxide, chemical (CRGO), hydrothermal (hTRGO), electrochemical (ERGO), and thermal (TRGO) reduced graphene oxide were produced. The materials were fully characterized and the topography and electroactivity of the resulting glassy carbon modified electrodes were also evaluated. An oligonucleotide molecule was used as a model of DNA electrochemical biosensing. The results allow for the conclusion that TRGO produced the RGOs with the best electrochemical performance for oligonucleotide electroanalysis. A clear shift in the guanine oxidation peak potential to lower values (~0.100 V) and an almost two-fold increase in the current intensity were observed compared with the other RGOs. The electrocatalytic effect has a multifactorial explanation because the TRGO was the material that presented a higher polydispersity and lower sheet size, thus exposing a larger quantity of defects to the electrode surface, which produces larger physical and electrochemical areas. PMID:28677654

  13. National Fire Plan - Hazardous Fuels Reduction Program - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This map layer portrays county level data for the fiscal-year-2004 National Fire Plan - Hazardous Fuels Reduction Program. The purpose of this program is to reduce...

  14. Direct reduction of nickel catalyst with model bio-compounds

    OpenAIRE

    Cheng, F; Dupont, V; Twigg, MV

    2017-01-01

    The effects of temperature and S/C on the reduction extent and kinetics of a steam reforming NiO/α-Al₂O₃ catalyst were systematically investigated using five bio-compounds commonly produced during the fermentation, pyrolysis and gasification processes of biomass (acetic acid, ethanol, acetone, furfural and glucose). Reduction was also performed with methane and hydrogen for comparison. Kinetic modelling was applied to the NiO conversion range of 0–50% using the Handcock and Sharp method. The ...

  15. Beneficiation of Titanium Oxides From Ilmenite by Self-Reduction of Coal Bearing Pellets

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The study on the beneficiation of titanium oxides from Panzhihua ilmenites by reduction of coal bearing pellets was carried out. The iron oxides in pellets were efficiently reduced to metal iron, and titanium oxide slag beneficiated was separated from metal iron. The effect of temperature, flux and coal blending ratio on the reduction and separation was investigated, and rational parameters were determined. A new process for the beneficiation of titanium oxides by rotary hearth furnace (RHF) was proposed.

  16. DIRECT REDUCTION OF HEMATITE POWDERS VIA COLD HYDROGEN PLASMA

    Directory of Open Access Journals (Sweden)

    Iraldo de Sá Silveira

    2014-12-01

    Full Text Available The goal of this work was to study the reduction kinetics of hematite powders (Fe2O3 using cold hydrogen plasma as reducing agent. Reduction experiments were carried out in a DC pulsed plasma reactor, under hydrogen flow-rates of 300 cm3/min, at pressure of 400 Pa, times from 30 to 120 minutes and temperatures of 320, 340, 360 and 380°C. Fe2O3 powders after reduction experiments were characterized by X-ray diffraction, weight loss of oxygen (gravimetric analyses and light microscopy. The results show that using a reduction temperature of 380°C after 120 min allows obtaining α-iron with a reduction fraction of about 0.93. The powder particles are transformed into two steps: Fe2O3→Fe3O4→Fe-α. The apparent activation energy experimentally established for the reduction of Fe2O3 is about 98.4 kJ/mol.

  17. Oxidation of Alpha-Ketoglutarate Is Required for Reductive Carboxylation in Cancer Cells with Mitochondrial Defects

    Directory of Open Access Journals (Sweden)

    Andrew R. Mullen

    2014-06-01

    Full Text Available Mammalian cells generate citrate by decarboxylating pyruvate in the mitochondria to supply the tricarboxylic acid (TCA cycle. In contrast, hypoxia and other impairments of mitochondrial function induce an alternative pathway that produces citrate by reductively carboxylating α-ketoglutarate (AKG via NADPH-dependent isocitrate dehydrogenase (IDH. It is unknown how cells generate reducing equivalents necessary to supply reductive carboxylation in the setting of mitochondrial impairment. Here, we identified shared metabolic features in cells using reductive carboxylation. Paradoxically, reductive carboxylation was accompanied by concomitant AKG oxidation in the TCA cycle. Inhibiting AKG oxidation decreased reducing equivalent availability and suppressed reductive carboxylation. Interrupting transfer of reducing equivalents from NADH to NADPH by nicotinamide nucleotide transhydrogenase increased NADH abundance and decreased NADPH abundance while suppressing reductive carboxylation. The data demonstrate that reductive carboxylation requires bidirectional AKG metabolism along oxidative and reductive pathways, with the oxidative pathway producing reducing equivalents used to operate IDH in reverse.

  18. Efficient and simple approaches towards direct oxidative esterification of alcohols.

    Science.gov (United States)

    Ray, Ritwika; Jana, Rahul Dev; Bhadra, Mayukh; Maiti, Debabrata; Lahiri, Goutam Kumar

    2014-11-17

    The present article describes novel oxidative protocols for direct esterification of alcohols. The protocols involve successful demonstrations of both "cross" and "self" esterification of a wide variety of alcohols. The cross-esterification proceeds under a simple transition-metal-free condition, containing catalytic amounts of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/TBAB (tetra-n-butylammonium bromide) in combination with oxone (potassium peroxo monosulfate) as the oxidant, whereas the self-esterification is achieved through simple induction of Fe(OAc)2 /dipic (dipic=2,6-pyridinedicarboxylic acid) as the active catalyst under an identical oxidizing environment.

  19. Iron isotope fractionation during microbial dissimilatory iron oxide reduction in simulated Archaean seawater.

    Science.gov (United States)

    Percak-Dennett, E M; Beard, B L; Xu, H; Konishi, H; Johnson, C M; Roden, E E

    2011-05-01

    The largest Fe isotope excursion yet measured in marine sedimentary rocks occurs in shales, carbonates, and banded iron formations of Neoarchaean and Paleoproterozoic age. The results of field and laboratory studies suggest a potential role for microbial dissimilatory iron reduction (DIR) in producing this excursion. However, most experimental studies of Fe isotope fractionation during DIR have been conducted in simple geochemical systems, using pure Fe(III) oxide substrates that are not direct analogues to phases likely to have been present in Precambrian marine environments. In this study, Fe isotope fractionation was investigated during microbial reduction of an amorphous Fe(III) oxide-silica coprecipitate in anoxic, high-silica, low-sulphate artificial Archaean seawater at 30 °C to determine if such conditions alter the extent of reduction or isotopic fractionations relative to those observed in simple systems. The Fe(III)-Si coprecipitate was highly reducible (c. 80% reduction) in the presence of excess acetate. The coprecipitate did not undergo phase conversion (e.g. to green rust, magnetite or siderite) during reduction. Iron isotope fractionations suggest that rapid and near-complete isotope exchange took place among all Fe(II) and Fe(III) components, in contrast to previous work on goethite and hematite, where exchange was limited to the outer few atom layers of the substrate. Large quantities of low-δ(56)Fe Fe(II) (aqueous and solid phase) were produced during reduction of the Fe(III)-Si coprecipitate. These findings shed new light on DIR as a mechanism for producing Fe isotope variations observed in Neoarchaean and Paleoproterozoic marine sedimentary rocks.

  20. Fast low-temperature plasma reduction of monolayer graphene oxide at atmospheric pressure

    Science.gov (United States)

    Bodik, Michal; Zahoranova, Anna; Micusik, Matej; Bugarova, Nikola; Spitalsky, Zdenko; Omastova, Maria; Majkova, Eva; Jergel, Matej; Siffalovic, Peter

    2017-04-01

    We report on an ultrafast plasma-based graphene oxide reduction method superior to conventional vacuum thermal annealing and/or chemical reduction. The method is based on the effect of non-equilibrium atmospheric-pressure plasma generated by the diffuse coplanar surface barrier discharge in proximity of the graphene oxide layer. As the reduction time is in the order of seconds, the presented method is applicable to the large-scale production of reduced graphene oxide layers. The short reduction times are achieved by the high-volume power density of plasma, which is of the order of 100 W cm‑3. Monolayers of graphene oxide on silicon substrate were prepared by a modified Langmuir–Schaefer method and the efficient and rapid reduction by methane and/or hydrogen plasma was demonstrated. The best results were obtained for the graphene oxide reduction in hydrogen plasma, as verified by x-ray photoelectron spectroscopy and Raman spectroscopy.

  1. Directions of the US Geological Survey Landslide Hazards Reduction Program

    Science.gov (United States)

    Wieczorek, G.F.

    1993-01-01

    The US Geological Survey (USGS) Landslide Hazards Reduction Program includes studies of landslide process and prediction, landslide susceptibility and risk mapping, landslide recurrence and slope evolution, and research application and technology transfer. Studies of landslide processes have been recently conducted in Virginia, Utah, California, Alaska, and Hawaii, Landslide susceptibility maps provide a very important tool for landslide hazard reduction. The effects of engineering-geologic characteristics of rocks, seismic activity, short and long-term climatic change on landslide recurrence are under study. Detailed measurement of movement and deformation has begun on some active landslides. -from Author

  2. Selective anaerobic oxidation of methane enables direct synthesis of methanol.

    Science.gov (United States)

    Sushkevich, Vitaly L; Palagin, Dennis; Ranocchiari, Marco; van Bokhoven, Jeroen A

    2017-05-05

    Direct functionalization of methane in natural gas remains a key challenge. We present a direct stepwise method for converting methane into methanol with high selectivity (~97%) over a copper-containing zeolite, based on partial oxidation with water. The activation in helium at 673 kelvin (K), followed by consecutive catalyst exposures to 7 bars of methane and then water at 473 K, consistently produced 0.204 mole of CH3OH per mole of copper in zeolite. Isotopic labeling confirmed water as the source of oxygen to regenerate the zeolite active centers and renders methanol desorption energetically favorable. On the basis of in situ x-ray absorption spectroscopy, infrared spectroscopy, and density functional theory calculations, we propose a mechanism involving methane oxidation at Cu(II) oxide active centers, followed by Cu(I) reoxidation by water with concurrent formation of hydrogen. Copyright © 2017, American Association for the Advancement of Science.

  3. Direct synthesis of graphene nanosheets support Pd nanodendrites for electrocatalytic formic acid oxidation

    Institute of Scientific and Technical Information of China (English)

    杨苏东; 陈琳

    2015-01-01

    We report a solvothermal method preparation of dendritic Pd nanoparticles (DPNs) and spherical Pd nanoparticles (SPNs) supported on reduced graphene oxide (RGO). Drastically different morphologies of Pd NPs with nanodendritic structures or spherical structures were observed on graphene by controlling the reduction degree of graphene oxide (GO) un-der mild conditions. In addition to being a commonplace substrate, GO plays a more important role that relies on its surface groups, which serves as a shape-directing agent to direct the dendritic growth. As a result, the obtained DPNs/RGO catalyst exhibits a significantly enhanced electro-catalytic behavior for the oxidation of formic acid compared to the SPNs/RGO catalyst.

  4. Two-stepped reduction of graphene oxide for improved electrical conductivity for sensor applications

    Science.gov (United States)

    Von Schleusingen, Mubaraq; Ahmad, Mohd Noor

    2017-03-01

    In the last decade graphene, and its derivatives, have received widespread attention for their applications in biotechnology, microelectronics, and other electrical industries. This paper establishes the benefits of a two part reduction procedure for graphene oxide to produce a highly conductive reduced graphene oxide. The procedure utilizes a chemical and microwave treatment to achieve reduction suitable for sensor applications.

  5. The effect of ammonia upon the electrocatalysis of hydrogen oxidation and oxygen reduction on polycrystalline platinum

    DEFF Research Database (Denmark)

    Verdaguer Casadevall, Arnau; Hernandez-Fernandez, Patricia; Stephens, Ifan E.L.

    2012-01-01

    The influence of ammonium ions on the catalysis of hydrogen oxidation and oxygen reduction is studied by means of rotating ring-disk electrode experiments on polycrystalline platinum in perchloric acid. While ammonium does not affect the hydrogen oxidation reaction, the oxygen reduction reaction ...

  6. Biotechnological aspects of anaerobic oxidation of methane coupled to sulfate reduction

    NARCIS (Netherlands)

    Meulepas, R.J.W.

    2009-01-01

    Sulfate reduction (SR) can be used for the removal and recovery of metals and oxidized sulfur compounds from waste streams. Sulfate-reducing bacteria reduce oxidized sulfur compounds to sulfide. Subsequently, sulfide can precipitate dissolved metals or can be oxidized to elemental sulfur. Both metal

  7. Effects of manganese oxide on arsenic reduction and leaching from contaminated floodplain soil

    DEFF Research Database (Denmark)

    Ehlert, Katrin; Mikutta, Christian; Kretzschmar, Ruben

    2016-01-01

    Reductive release of the potentially toxic metalloid As from Fe(III) (oxyhydr)oxides has been identified as an important process leading to elevated As porewater concentrations in soils and sediments. Despite the ubiquitous presence of Mn oxides in soils and their oxidizing power toward As...

  8. Biotechnological aspects of anaerobic oxidation of methane coupled to sulfate reduction

    NARCIS (Netherlands)

    Meulepas, R.J.W.

    2009-01-01

    Sulfate reduction (SR) can be used for the removal and recovery of metals and oxidized sulfur compounds from waste streams. Sulfate-reducing bacteria reduce oxidized sulfur compounds to sulfide. Subsequently, sulfide can precipitate dissolved metals or can be oxidized to elemental sulfur. Both metal

  9. Direct reduction of hematite powders in a fluidized bed reactor

    Institute of Scientific and Technical Information of China (English)

    Qingshan Zhu; Rongfang Wu; Hongzhong Li

    2013-01-01

    Ultrafine hematite powder was reduced to produce ultrafine iron powder in a 50%Ar-50%H2 atmosphere at 450-550 ℃ in a fluidized bed reactor.The ultrafine hematite powder shows the typical agglomerating fluidization behavior with large agglomerates fluidized at the bottom of the bed and small agglomerates fluidized at the upper part of the bed.It was found that defluidization occurred even at the low temperature of 450 ℃ with low metallization rate.Defluidization was attributed mainly to the sintering of the newly formed iron particles.Granuation was employed to improve the fluidization quality and to tackle the defluidization problem,where granules fluidized like a Geldart's group A powder.Granulation was found to effectively reduce defluidization during reduction,without however sacrificing reduction speed.The asreduced iron powders from both the ultrafine and the granulated hematite exhibited excellent sintering activity,that is,fast sintering at temperature of as low as ~580 ℃,which is much superior as compared to that of nano/ultrafine iron powders made by other processes,

  10. A new green approach for the reduction of graphene oxide nanosheets using caffeine

    Indian Academy of Sciences (India)

    Thu Ha Thi Vu; Thanh Thuy Thi Tran; Hong Ngan Thi Le; Phuong Hoa Thi Nguyen; Ngoc Quynh Bui; Nadine Essayem

    2015-06-01

    A simple and green chemistry approach for the preparation of reduced graphene oxide nanosheets was successfully demonstrated through the reduction of graphene oxide (GO) using caffeine as the reductant. Without using toxic and harmful chemicals, this method is environmentally friendly and suitable for the large-scale production of graphene. The samples of GO, before and after reduction with caffeine have been characterized by X-ray diffraction, Raman, Fourier transform infrared, X-ray photoelectron spectroscopy, thermogravimetric analysis and transmission electron microscopy.

  11. Effect of electrolysis voltage on electrochemical reduction of titanium oxide to titanium in molten calcium chloride

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The electrochemical reduction of solid TiO2 directly to solid metal is a ptomising alternative to the current Kroll process. The present work is aimed at studying the effect of electrolysis voltage on the rate of electrochemical reduction. The products of electrochemical reduction of TiO2 and Ti2O were examined using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The results show that Ti2O was reduced to low valent titanium oxide at 1.5 -1.7 V, which was the result of ionization of oxygen. TiO2 and Ti2O were reduced to titanium metal at 2.1-3.1 V, which was the co-action of ionization of oxygen and calciothermic reduction. The oxygen content decreased rapidly with voltage increasing from 2.1 to 2.6 V, while it changed little from 2.6 to 3.1 V. The optimized cell voltage was 2.6-3.1 V.

  12. Reduction of a thin chromium oxide film on Inconel surface upon treatment with hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vesel, Alenka, E-mail: alenka.vesel@guest.arnes.si [Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Mozetic, Miran [Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Balat-Pichelin, Marianne [PROMES-CNRS Laboratory, 7 Rue du four solaire, 66120 Font Romeu Odeillo (France)

    2016-11-30

    Highlights: • Oxidized Inconel alloy was exposed to hydrogen at temperatures up to 1500 K. • Oxide reduction in hydrogen plasma started at approximately 1300 K. • AES depth profiling revealed complete reduction of oxides in plasma. • Oxides were not reduced, if the sample was heated just in hydrogen atmosphere. • Surface of reduced Inconel preserved the same composition as the bulk material. - Abstract: Inconel samples with a surface oxide film composed of solely chromium oxide with a thickness of approximately 700 nm were exposed to low-pressure hydrogen plasma at elevated temperatures to determine the suitable parameters for reduction of the oxide film. The hydrogen pressure during treatment was set to 60 Pa. Plasma was created by a surfaguide microwave discharge in a quartz glass tube to allow for a high dissociation fraction of hydrogen molecules. Auger electron depth profiling (AES) was used to determine the decay of the oxygen in the surface film and X-ray diffraction (XRD) to measure structural modifications. During hydrogen plasma treatment, the oxidized Inconel samples were heated to elevated temperatures. The reduction of the oxide film started at temperatures of approximately 1300 K (considering the emissivity of 0.85) and the oxide was reduced in about 10 s of treatment as revealed by AES. The XRD showed sharper substrate peaks after the reduction. Samples treated in hydrogen atmosphere under the same conditions have not been reduced up to approximately 1500 K indicating usefulness of plasma treatment.

  13. Finding optimal HBr reduction of inkjet printed graphene oxide for flexible electronics

    Energy Technology Data Exchange (ETDEWEB)

    Wlasny, I., E-mail: igor.wlasny@fuw.edu.pl [Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236, Lodz (Poland); Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02 093, Warsaw (Poland); Rogala, M.; Dabrowski, P.; Kowalczyk, P.J.; Busiakiewicz, A.; Kozlowski, W. [Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236, Lodz (Poland); Lipinska, L.; Jagiello, J.; Aksienionek, M. [Institute of Electronic Materials Technology, Wolczynska 133, 01-919, Warsaw (Poland); Sieradzki, Z. [Electrotechnological Company QWERTY Ltd., Siewna 21, 94-250, Lodz (Poland); Krucinska, I.; Puchalski, M.; Skrzetuska, E.; Draczynski, Z. [Department of Material and Commodity Sciences and Textile Metrology, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz (Poland); Klusek, Z. [Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236, Lodz (Poland)

    2016-09-15

    In this article we present the results of our investigations of reduction of graphene oxide overprints, deposited by ink-jet method, by hydrobromic acid. Our study presents impact of different parameters of reduction, such as a temperature and time of the process on the chemical composition and electrical conductivity of the resulting material – reduced graphene oxide. Our results show the outstanding potential of this method for use in the production of flexible and elastic electronics and indicate the optimal parameters of reduction, which allow producing the optimal product. - Highlights: • The process of reduction of graphene oxide inkjet printouts by HBr is investigated. • Impact of parameters of reduction on the chemical structure of printout is studied. • Impact of parameters of reduction on the sheet resistance of printout is studied. • Optimal parameters of reduction are proposed.

  14. Direct reduction of iron ore by biomass char

    Science.gov (United States)

    Zuo, Hai-bin; Hu, Zheng-wen; Zhang, Jian-liang; Li, Jing; Liu, Zheng-jian

    2013-06-01

    By using thermogravimetric analysis the process and mechanism of iron ore reduced by biomass char were investigated and compared with those reduced by coal and coke. It is found that biomass char has a higher reactivity. The increase of carbon-to-oxygen mole ratio (C/O) can lead to the enhancement of reaction rate and reduction fraction, but cannot change the temperature and trend of each reaction. The reaction temperature of hematite reduced by biomass char is at least 100 K lower than that reduced by coal and coke, the maximum reaction rate is 1.57 times as high as that of coal, and the final reaction fraction is much higher. Model calculation indicates that the use of burden composed of biomass char and iron ore for blast furnaces can probably decrease the temperature of the thermal reserve zone and reduce the CO equilibrium concentration.

  15. Graphene produced by radiation-induced reduction of graphene oxide

    OpenAIRE

    Kumar, Prashant; K. S. Subrahmanyam; Rao, C. N. R.

    2010-01-01

    Effect of irradiation on graphene oxide by sunlight, UV light and KrF excimer laser has been investigated in detail. Both sunlight and ultraviolet light reduce graphene oxide well after prolonged irradiation, but laser irradiation produces graphene with negligible oxygen functionalities within a short time. Laser irradiation is also useful for one-step synthesis of metal particle decorated graphene. Laser irradiation of graphene oxide appears to be an efficient procedure for large-scale synth...

  16. Graphene produced by radiation-induced reduction of graphene oxide

    OpenAIRE

    Kumar, Prashant; Subrahmanyam, K. S.; Rao, C. N. R.

    2010-01-01

    Effect of irradiation on graphene oxide by sunlight, UV light and KrF excimer laser has been investigated in detail. Both sunlight and ultraviolet light reduce graphene oxide well after prolonged irradiation, but laser irradiation produces graphene with negligible oxygen functionalities within a short time. Laser irradiation is also useful for one-step synthesis of metal particle decorated graphene. Laser irradiation of graphene oxide appears to be an efficient procedure for large-scale synth...

  17. Outer cell surface components essential for Fe(III) oxide reduction by Geobacter metallireducens.

    Science.gov (United States)

    Smith, Jessica A; Lovley, Derek R; Tremblay, Pier-Luc

    2013-02-01

    Geobacter species are important Fe(III) reducers in a diversity of soils and sediments. Mechanisms for Fe(III) oxide reduction have been studied in detail in Geobacter sulfurreducens, but a number of the most thoroughly studied outer surface components of G. sulfurreducens, particularly c-type cytochromes, are not well conserved among Geobacter species. In order to identify cellular components potentially important for Fe(III) oxide reduction in Geobacter metallireducens, gene transcript abundance was compared in cells grown on Fe(III) oxide or soluble Fe(III) citrate with whole-genome microarrays. Outer-surface cytochromes were also identified. Deletion of genes for c-type cytochromes that had higher transcript abundance during growth on Fe(III) oxides and/or were detected in the outer-surface protein fraction identified six c-type cytochrome genes, that when deleted removed the capacity for Fe(III) oxide reduction. Several of the c-type cytochromes which were essential for Fe(III) oxide reduction in G. metallireducens have homologs in G. sulfurreducens that are not important for Fe(III) oxide reduction. Other genes essential for Fe(III) oxide reduction included a gene predicted to encode an NHL (Ncl-1-HT2A-Lin-41) repeat-containing protein and a gene potentially involved in pili glycosylation. Genes associated with flagellum-based motility, chemotaxis, and pili had higher transcript abundance during growth on Fe(III) oxide, consistent with the previously proposed importance of these components in Fe(III) oxide reduction. These results demonstrate that there are similarities in extracellular electron transfer between G. metallireducens and G. sulfurreducens but the outer-surface c-type cytochromes involved in Fe(III) oxide reduction are different.

  18. Controlled Growth of Copper Oxide Nano-Wires through Direct Oxidation

    Science.gov (United States)

    Hilman, Joann; Neupane, Ravi; Yost, Andrew J.; Chien, Teyu

    Copper oxides, both Cu2O and CuO, have many applications in solar cells, sensors, and nano-electronics. The properties of the copper oxides are further influenced by the dimension of the materials, especially when made in nanoscale. In particular, the properties of the copper oxide nanowires could be tuned by their structures, lengths, and widths. While several methods have been reported to grow nanowires, direct oxidation is arguably the most economical one. This research examines the effects of oxidization duration and temperature in dry air environment on the development of copper oxide nanowires in order to achieve cost effective controllable growth. Using the direct oxidation method in dry air we have demonstrated growth of CuO nano-wires at temperatures as low as 300 °C and as short as 1hr. Furthermore we have observed that the lengths and diameters of the CuO NWs can be controlled by the duration and temperature of the oxidation process. WY NASA Space Grant Consortium.

  19. Molecular Underpinnings of Fe(III Oxide Reduction by Shewanella oneidensis MR-1

    Directory of Open Access Journals (Sweden)

    Liang eShi

    2012-02-01

    Full Text Available In the absence of O2 and other electron acceptors, the Gram-negative bacterium Shewanella oneidensis MR-1 can use ferric [Fe(III] (oxy(hydroxide minerals as the terminal electron acceptors for anaerobic respiration. At circumneutral pH and in the absence of strong complexing ligands, Fe(III oxides are relatively insoluble and thus are external to the bacterial cells. S. oneidensis MR-1 has evolved the machinery (i.e., metal-reducing or Mtr pathway for transferring electrons across the entire cell envelope to the surface of extracellular Fe(III oxides. The protein components identified to date for the Mtr pathway include CymA, MtrA, MtrB, MtrC and OmcA. CymA is an inner-membrane tetraheme c-type cytochrome (c-Cyt that is proposed to oxidize the quinol in the inner-membrane and transfers the released electrons to redox proteins in the periplasm. Although the periplasmic proteins receiving electrons from CymA during Fe(III oxidation have not been identified, they are believed to relay the electrons to MtrA. A decaheme c-Cyt, MtrA is thought to be embedded in the trans outer-membrane and porin-like protein MtrB. Together, MtrAB deliver the electrons across the outer-membrane to the MtrC and OmcA on the outmost bacterial surface. Functioning as terminal reductases, the outer membrane and decaheme c-Cyts MtrC and OmcA can bind the surface of Fe(III oxides and transfer electrons directly to these minerals. To increase their reaction rates, MtrC and OmcA can use the flavins secreted by S. oneidensis MR-1 cells as diffusible co-factors for reduction of Fe(III oxides. MtrC and OmcA can also serve as the terminal reductases for soluble forms of Fe(III. Although our understanding of the Mtr pathway is still far from complete, it is the best characterized microbial pathway used for extracellular electron exchange. Characterizations of the Mtr pathway have made significant contributions to the molecular understanding of microbial reduction of Fe(III oxides.

  20. Effect of grain size reduction on high temperature oxidation ofbinary two-phase alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of grain size reduction on the high temperature oxidation of binary two-phase alloys was discussed based on the recent research progress. The results show that for those two-phase alloys with coarse grain prepared by the conventional methods, complex oxide scales are easily formed after oxidation under high oxygen pressure or under oxygen pressure below the stability limit of the less reactive component oxides. On the contrary, for the nano-sized alloys, an exclusive external oxidation of the most reactive component usually occurs during oxidation in air or pure oxygen even for much lower content of the most reactive component. So the gain size reduction is not always beneficial to improve the oxidation resistance of the materials, but exhibits different effects depending mainly on the protective feature of the scales. The transition mechanisms between the different oxidation modes are discussed with respect to the thermodynamic and dynamic aspects.

  1. Direct laser printing of graphene oxide for resistive chemosensors

    Science.gov (United States)

    Papazoglou, S.; Tsouti, V.; Chatzandroulis, S.; Zergioti, I.

    2016-08-01

    This work presents the pulsed laser printing of graphene oxide, and a subsequent thermal reduction step, aiming towards the fabrication of a chemical sensor device that operates at room temperature. Laser printing was performed using the Laser Induced Forward Transfer technique, which enables for the rapid and highly resolved deposition of liquid and solid phase materials, while printing conditions were also studied, in terms of optimum laser fluence regime and donor-receiver substrates distance, so as to avoid undesirable satellite debris, which has detrimental effects on the sensor performance such as adjacent sensor cross-talk, etc. The evaluation of the reduction efficiency was made by Fourier Transform Reflectance spectroscopy and electrical characterization of the thermally reduced devices. Finally, the response of the sensor upon exposure to water vapors is evaluated, and sensitivities down to 0.22%/%RH were recorded.

  2. Direct chemical oxidation of mixed or toxic wastes

    Energy Technology Data Exchange (ETDEWEB)

    Balazs, G B; Cooper, J F; Farmer, J C; Lewis, P

    1999-05-01

    Direct Chemical Oxidation (DCO) is an ambient-pressure, low-temperature (<100 C), and aqueous-based process for general-purpose destruction of the organic fraction of hazardous or mixed waste. It uses the peroxydisulfate anion (S{sub 2}O{sub 8}{sup 2{minus}}) in acid or base solutions. The byproduct of the oxidation reaction, typically sodium or ammonium hydrogen sulfate, may be recycled electrolytically to produce the oxidant. The oxidation kinetic reaction is first order with respect to the peroxydisulfate concentration, expressed in equivalents. The rate constant is constant for nearly all dissolved organic compounds: k{sub a} = 0.01 {+-} 0.005 min{sup {minus}1}. This reflects a common rate-determining step, which is the decomposition of the peroxydisulfate anion into the chemically active derivative, the sulfate radical anion, SO{sub 4}{sup {minus}}. This decomposition is promoted in DCO by raising the operating temperature into the range of 80-100 C. Rates are given for approximately 30 substances with diverse functional groups at low concentrations, and for a number of solid and liquid wastes typical of nuclear and chemical industries. The process has been scale up for treatment studies on chlorinated hydrocarbons, in which the hydrolysis of solvent mixtures was followed by oxidation of products in a series of stirred tank reactors. Cost estimates, safety considerations, and a comprehensive bibliography are given.

  3. Comparative studies on single-layer reduced graphene oxide films obtained by electrochemical reduction and hydrazine vapor reduction

    Science.gov (United States)

    Wang, Zhijuan; Wu, Shixin; Zhang, Juan; Chen, Peng; Yang, Guocheng; Zhou, Xiaozhu; Zhang, Qichun; Yan, Qingyu; Zhang, Hua

    2012-02-01

    The comparison between two kinds of single-layer reduced graphene oxide (rGO) sheets, obtained by reduction of graphene oxide (GO) with the electrochemical method and hydrazine vapor reduction, referred to as E-rGO and C-rGO, respectively, is systematically studied. Although there is no morphology difference between the E-rGO and C-rGO films adsorbed on solid substrates observed by AFM, the reduction process to obtain the E-rGO and C-rGO films is quite different. In the hydrazine vapor reduction, the nitrogen element is incorporated into the obtained C-rGO film, while no additional element is introduced to the E-rGO film during the electrochemical reduction. Moreover, Raman spectra show that the electrochemical method is more effective than the hydrazine vapor reduction method to reduce the GO films. In addition, E-rGO shows better electrocatalysis towards dopamine than does C-rGO. This study is helpful for researchers to understand these two different reduction methods and choose a suitable one to reduce GO based on their experimental requirements.

  4. Dissimilatory perchlorate reduction linked to aerobic methane oxidation via chlorite dismutase

    Science.gov (United States)

    Oremland, R. S.; Baesman, S. M.; Miller, L. G.

    2013-12-01

    The presence of methane (CH4) in the atmosphere of Mars is controversial yet the evidence has aroused scientific interest, as CH4 could be a harbinger of extant or extinct microbial life. There are various oxidized compounds present on the surface of Mars that could serve as electron acceptors for the anaerobic oxidation of CH4, including perchlorate (ClO4-). We examined the role of perchlorate, chlorate (ClO3-) and chlorite (ClO2-) as oxidants linked to CH4 oxidation. Dissimilatory perchlorate reduction begins with reduction of ClO4- to ClO2- and ends with dismutation of chlorite to yield chloride (Cl-) and molecular oxygen (O2). We explored the potential for aerobic CH4 oxidizing bacteria to couple with oxygen derived from chlorite dismutation during dissimilatory perchlorate reduction. Methane (0.2 kPa) was completely removed within several days from the N2-flushed headspace above cell suspensions of methanotrophs (Methylobacter albus strain BG8) and perchlorate reducing bacteria (Dechloromonas agitata strain CKB) in the presence of 5 mM ClO2-. Similar rates of CH4 consumption were observed for these mixed cultures whether they were co-mingled or segregated under a common headspace, indicating that direct contact of cells was not required for methane consumption to occur. We also observed complete removal of 0.2 kPa CH4 in bottles containing dried soil (enriched in methanotrophs by CH4 additions over several weeks) and D. agitata CKB and in the presence of 10 mM ClO2-. This soil (seasonally exposed sediment) collected from the shoreline of a freshwater lake (Searsville Lake, CA) demonstrated endogenous CH4 uptake as well as perchlorate, chlorate and chlorite reduction/dismutation. However, these experiments required physical separation of soil from the aqueous bacterial culture to allow for the partitioning of O2 liberated from chlorite dismutation into the shared headspace. Although dissimilatory reduction of ClO4- and ClO3- could be inferred from the

  5. Abiotic reduction of nitroaromatic compounds by Fe(II) associated with iron oxides and humic acid.

    Science.gov (United States)

    Luan, Fubo; Xie, Li; Li, Jun; Zhou, Qi

    2013-05-01

    Experiments were conducted to examine the reduction of nitroaromatic compounds (NACs) by Fe(II) associated with iron oxides (goethite, hematite and magnetite) and humic acid. The reduction rate of nitrobenzene decreased in the order of Fe(II) associated with magnetite>Fe(II) associated with goethite>Fe(II) associated with hematite. We proposed a four-step model (adsorption, electron transfer to conduction band, electron transfer to nitrobenzene and electron transfer to crystal lattice) for nitrobenzene reduction by Fe(II) associated with iron oxides. Fe(II)-humic acid complexes did not present reduction capability of nitrobenzene. Furthermore, Humic acid significantly inhibited nitrobenzene reduction by Fe(II) associated with iron oxides. The inhibitory effect of humic acid toward the reduction of nitrobenzene decreased in the order of magnetite>goethite>hematite. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Oxygen Reduction Kinetics Enhancement on a Heterostructured Oxide Surface for Solid Oxide Fuel Cells

    KAUST Repository

    Crumlin, Ethan J.

    2010-11-04

    Heterostructured interfaces of oxides, which can exhibit transport and reactivity characteristics remarkably different from those of bulk oxides, are interesting systems to explore in search of highly active cathodes for the oxygen reduction reaction (ORR). Here, we show that the ORR of ∼85 nm thick La0.8Sr0.2CoO3-δ (LSC113) films prepared by pulsed laser deposition on (001)-oriented yttria-stabilized zirconia (YSZ) substrates is dramatically enhanced (∼3-4 orders of magnitude above bulk LSC113) by surface decorations of (La 0.5Sr0.5)2CoO4±δ (LSC214) with coverage in the range from ∼0.1 to ∼15 nm. Their surface and atomic structures were characterized by atomic force, scanning electron, and scanning transmission electron microscopy, and the ORR kinetics were determined by electrochemical impedance spectroscopy. Although the mechanism for ORR enhancement is not yet fully understood, our results to date show that the observed ORR enhancement can be attributed to highly active interfacial LSC113/LSC214 regions, which were shown to be atomically sharp. © 2010 American Chemical Society.

  7. The oxidation and reduction of chromium of stainless steels in an eletric arc furnace

    Directory of Open Access Journals (Sweden)

    B. Arh

    2011-07-01

    Full Text Available The oxidation of chromium during the elaboration of stainless steels occurs with oxygen in solution blown inthe melt and with oxides in the slag. A higher content of silicon in the furnace charge decreases the extent of oxidation of chromium, however, the efficient reduction of chromium from the slag is of essential importance for a minimal loss of chromium. In this survey, the theory of the oxidation of chromium, its reduction from the slag and the conditions for the formation of foaming slag are discussed.

  8. Extracellular electron transfer to Fe(III) oxides by the hyperthermophilic archaeon Geoglobus ahangari via a direct contact mechanism.

    Science.gov (United States)

    Manzella, Michael P; Reguera, Gemma; Kashefi, Kazem

    2013-08-01

    The microbial reduction of Fe(III) plays an important role in the geochemistry of hydrothermal systems, yet it is poorly understood at the mechanistic level. Here we show that the obligate Fe(III)-reducing archaeon Geoglobus ahangari uses a direct-contact mechanism for the reduction of Fe(III) oxides to magnetite at 85°C. Alleviating the need to directly contact the mineral with the addition of a chelator or the electron shuttle anthraquinone-2,6-disulfonate (AQDS) stimulated Fe(III) reduction. In contrast, entrapment of the oxides within alginate beads to prevent cell contact with the electron acceptor prevented Fe(III) reduction and cell growth unless AQDS was provided. Furthermore, filtered culture supernatant fluids had no effect on Fe(III) reduction, ruling out the secretion of an endogenous mediator too large to permeate the alginate beads. Consistent with a direct contact mechanism, electron micrographs showed cells in intimate association with the Fe(III) mineral particles, which once dissolved revealed abundant curled appendages. The cells also produced several heme-containing proteins. Some of them were detected among proteins sheared from the cell's outer surface and were required for the reduction of insoluble Fe(III) oxides but not for the reduction of the soluble electron acceptor Fe(III) citrate. The results thus support a mechanism in which the cells directly attach and transfer electrons to the Fe(III) oxides using redox-active proteins exposed on the cell surface. This strategy confers on G. ahangari a competitive advantage for accessing and reducing Fe(III) oxides under the extreme physical and chemical conditions of hot ecosystems.

  9. Fluidized reduction of oxides on fine metal powders without sintering

    Science.gov (United States)

    Hayashi, T.

    1985-01-01

    In the process of reducing extremely fine metal particles (av. particle size or = 1000 angstroms) covered with an oxide layer, the metal particles are fluidized by a gas flow contg. H, heated, and reduced. The method uniformly and easily reduces surface oxide layers of the extremely fine metal particles without causing sintering. The metal particles are useful for magnetic recording materials, conductive paste, powder metallurgy materials, chem. reagents, and catalysts.

  10. Direct oxidation of polymeric substrates by multifunctional manganese peroxidase isoenzyme from Pleurotus ostreatus without redox mediators

    Science.gov (United States)

    2004-01-01

    VPs (versatile peroxidases) sharing the functions of LiP (lignin peroxidase) and MnP (manganese peroxidase) have been described in basidiomycetous fungi Pleurotus and Bjerkandera. Despite the importance of this enzyme in polymer degradation, its reactivity with polymeric substrates remains poorly understood. In the present study, we first report that, unlike LiP, VP from Pleurotus ostreatus directly oxidized two polymeric substrates, bovine pancreatic RNase and Poly R-478, through a long-range electron pathway without redox mediators. P. ostreatus produces several MnP isoenzymes, including the multifunctional enzyme MnP2 (VP) and a typical MnP isoenzyme MnP3. MnP2 (VP) depolymerized a polymeric azo dye, Poly R-478, to complete its catalytic cycle. Reduction of the oxidized intermediates of MnP2 (VP) to its resting state was also observed for RNase. RNase inhibited the oxidation of VA (veratryl alcohol) in a competitive manner. Blocking of the exposed tryptophan by N-bromosuccinimide inhibited the oxidation of RNase and VA by MnP2 (VP), but its Mn2+-oxidizing activity was retained, suggesting that Trp-170 exposed on an enzyme surface is a substrate-binding site both for VA and the polymeric substrates. The direct oxidation of RNase and Poly R by MnP2 (VP) is in sharp contrast with redox mediator-dependent oxidation of these polymers by LiP from Phanerochaete chrysosporium. Molecular modelling of MnP2 (VP) revealed that the differences in the dependence on redox mediators in polymer oxidation by MnP2 (VP) and LiP were explained by the anionic microenvironment surrounding the exposed tryptophan. PMID:15461584

  11. Interfacial Reduction-Oxidation Mechanisms Governing Fate and Transport of Contaminants in the Vadose Zone

    Energy Technology Data Exchange (ETDEWEB)

    Principal Investigator: Baolin Deng, University of Missouri, Columbia, MO; Co-Principal Investigator: Silvia Sabine Jurisson, University of Missouri, Columbia, MO; Co-Principal Investigator: Edward C. Thornton, Pacific Northwest National Laboratory Richland, WA; Co-Principal Investigator: Jeff Terry, Illinois Institute of Technology, Chicago, IL

    2008-05-12

    There are many soil contamination sites at the Department of Energy (DOE) installations that contain radionuclides and toxic metals such as uranium (U), technetium (Tc), and chromium (Cr). Since these contaminants are the main 'risk drivers' at the Hanford site (WA) and some of them also pose significant risk at other DOE facilities (e.g., Oak Ridge Reservation - TN; Rocky Flats - CO), development of technologies for cost effective site remediation is needed. Current assessment indicates that complete removal of these contaminants for ex-situ disposal is infeasible, thus in-situ stabilization through reduction to insoluble species is considered one of the most important approaches for site remediation. In Situ Gaseous Reduction (ISGR) is a technology developed by Pacific Northwest National Laboratory (PNNL) for vadose zone soil remediation. The ISGR approach uses hydrogen sulfide (H{sub 2}S) for reductive immobilization of contaminants that show substantially lower mobility in their reduced forms (e.g., Tc, U, and Cr). The technology can be applied in two ways: (i) to immobilize or stabilize pre-existing contaminants in the vadose zone soils by direct H{sub 2}S treatment, or (ii) to create a permeable reactive barrier (PRB) that prevents the migration of contaminants. Direct treatment involves reduction of the contaminants by H{sub 2}S to less mobile species. Formation of a PRB is accomplished through reduction of ferric iron species in the vadose zone soils by H{sub 2}S to iron sulfides (e.g., FeS), which provides a means for capturing the contaminants entering the treated zone. Potential future releases may occur during tank closure activities. Thus, the placement of a permeable reactive barrier by ISGR treatment can be part of the leak mitigation program. Deployment of these ISGR approaches, however, requires a better understanding of the immobilization kinetics and mechanisms, and a better assessment of the long-term effectiveness of treatment. The

  12. Biomineralization associated with microbial reduction of Fe3+ and oxidation of Fe2+ in solid minerals

    Science.gov (United States)

    Zhang, G.; Dong, H.; Jiang, H.; Kukkadapu, R.K.; Kim, J.; Eberl, D.; Xu, Z.

    2009-01-01

    Iron-reducing and oxidizing microorganisms gain energy through reduction or oxidation of iron, and by doing so play an important role in the geochemical cycling of iron. This study was undertaken to investigate mineral transformations associated with microbial reduction of Fe3+ and oxidation of Fe2+ in solid minerals. A fluid sample from the 2450 m depth of the Chinese Continental Scientific Drilling project was collected, and Fe3+-reducing and Fe2+-oxidizing microorganisms were enriched. The enrichment cultures displayed reduction of Fe3+ in nontronite and ferric citrate, and oxidation of Fe2+ in vivianite, siderite, and monosulfide (FeS). Additional experiments verified that the iron reduction and oxidation was biological. Oxidation of FeS resulted in the formation of goethite, lepidocrocite, and ferrihydrite as products. Although our molecular microbiological analyses detected Thermoan-aerobacter ethanolicus as a predominant organism in the enrichment culture, Fe3+ reduction and Fe2+ oxidation may be accomplished by a consortia of organisms. Our results have important environmental and ecological implications for iron redox cycling in solid minerals in natural environments, where iron mineral transformations may be related to the mobility and solubility of inorganic and organic contaminants.

  13. Trace methane oxidation and the methane dependency of sulfate reduction in anaerobic granular sludge

    KAUST Repository

    Meulepas, Roel J.W.

    2010-05-01

    This study investigates the oxidation of labeled methane (CH4) and the CH4 dependence of sulfate reduction in three types of anaerobic granular sludge. In all samples, 13C-labeled CH4 was anaerobically oxidized to 13C-labeled CO2, while net endogenous CH4 production was observed. Labeled-CH4 oxidation rates followed CH4 production rates, and the presence of sulfate hampered both labeled-CH4 oxidation and methanogenesis. Labeled-CH4 oxidation was therefore linked to methanogenesis. This process is referred to as trace CH4 oxidation and has been demonstrated in methanogenic pure cultures. This study shows that the ratio between labeled-CH4 oxidation and methanogenesis is positively affected by the CH4 partial pressure and that this ratio is in methanogenic granular sludge more than 40 times higher than that in pure cultures of methanogens. The CH4 partial pressure also positively affected sulfate reduction and negatively affected methanogenesis: a repression of methanogenesis at elevated CH4 partial pressures confers an advantage to sulfate reducers that compete with methanogens for common substrates, formed from endogenous material. The oxidation of labeled CH 4 and the CH4 dependence of sulfate reduction are thus not necessarily evidence of anaerobic oxidation of CH4 coupled to sulfate reduction. © 2010 Federation of European Microbiological Societies.

  14. Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Moussavi, Gholamreza, E-mail: moussavi@modares.ac.ir; Shekoohiyan, Sakine

    2016-11-15

    Highlights: • Simultaneous advanced oxidation and reduction processes were explored in VUV system. • Complete reduction of nitrate to N{sub 2} was achieved at the presence of acetaminophen. • Complete degradation of acetaminophen was achieved at the presence of nitrate. • Over 95% of acetaminophen was mineralized in the VUV photoreactor. • VUV is a chemical-less advanced process for treating water emerging contaminants. - Abstract: This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO· while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N{sub 2} selectivity achieved at HRT of 80 min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80 min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate.

  15. Safety analysis of switching between reductive and oxidative conditions in a reaction coupling reverse flow reactor.

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    2001-01-01

    A new reverse flow reactor is developed where endothermic reactants (propane dehydrogenation) and exothermic reactants (fuel combustion) are fed sequentially to a monolithic catalyst, while periodically alternating the inlet and outlet positions. Upon switching from reductive to oxidative conditions

  16. Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

    This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was

  17. Palladium-catalyzed reductive homocoupling of aromatic halides and oxidation of alcohols.

    Science.gov (United States)

    Zeng, Minfeng; Du, Yijun; Shao, Linjun; Qi, Chenze; Zhang, Xian-Man

    2010-04-16

    Palladium-catalyzed reductive homocoupling of aromatic halides can be performed in alcohol solutions without any auxiliary reducing reagents. Pd(dppf)Cl(2) [dppf = 1,1'-bis(diphenylphosphino)ferrocene] has been shown as the most effective catalyst among the palladium catalysts screened for the model reductive homocoupling of iodobenzene in alcoholic solutions. The reduction of iodobenzene is stoichiometrically coupled with the oxidation of solvent alcohol (3-pentanol). The X-ray photoelectron spectroscopic (XPS) studies clearly indicate that the oxidation of solvent alcohol molecules is involved with the in situ regeneration of the reductive Pd(0)(dppf) active species, indicating that the solvent alcohol also reacts as a reducing reagent for the reductive homocoupling of aromatic halides. Elimination of the external reducing reagents will simplify the product separation and purification. Base is essential for the success of the Pd(dppf)Cl(2)-catalyzed redox reaction as 2 molar equiv of base is needed to neutralize the acid byproduct formed. Biaryls are the predominant products for the Pd(dppf)Cl(2)-catalyzed reductions of the unsubstituted aromatic halides in 3-pentanol solution, whereas the dehalogenation products are predominant for the Pd(dppf)Cl(2)-catalyzed reductions of the substituted aromatic halides. The reaction mechanisms have been discussed for the palladium-mediated concomitant reduction of aromatic halides and oxidation of alcohols without any auxiliary reductants and oxidants.

  18. Reduction study of oxidized two-dimensional graphene-based materials by chemical and thermal reduction methods

    Science.gov (United States)

    Douglas, Amber M.

    Graphene is a two-dimensional (2D) sp2-hybridized carbon-based material possessing properties which include high electrical conductivity, ballistic thermal conductivity, tensile strength exceeding that of steel, high flexural strength, optical transparency, and the ability to adsorb and desorb atoms and molecules. Due to the characteristics of said material, graphene is a candidate for applications in integrated circuits, electrochromic devices, transparent conducting electrodes, desalination, solar cells, thermal management materials, polymer nanocomposites, and biosensors. Despite the above mentioned properties and possible applications, very few technologies have been commercialized utilizing graphene due to the high cost associated with the production of graphene. Therefore, a great deal of effort and research has been performed to produce a material that provides similar properties, reduced graphene oxide due (RGO) to the ease of commercial scaling of the production processes. This material is typically prepared through the oxidation of graphite in an aqueous media to graphene oxide (GO) followed by reduction to yield RGO. Although this material has been extensively studied, there is a lack of consistency in the scientific community regarding the analysis of the resulting RGO material. In this dissertation, a study of the reduction methods for GO and an alternate 2D carbon-based material, humic acid (HA), followed by analysis of the materials using Raman spectroscopy and Energy Dispersive X-ray Spectroscopy (EDS). Means of reduction will include chemical and thermal methods. Characterization of the material has been carried out on both before and after reduction.

  19. Ceruloplasmin copper induces oxidant damage by a redox process utilizing cell-derived superoxide as reductant

    Science.gov (United States)

    Mukhopadhyay, C. K.; Fox, P. L.

    1998-01-01

    Oxidative damage by transition metals bound to proteins may be an important pathogenic mechanism. Ceruloplasmin (Cp) is a Cu-containing plasma protein thought to be involved in oxidative modification of lipoproteins. We have previously shown that Cp increased cell-mediated low-density lipoprotein (LDL) oxidation by a process requiring cell-derived superoxide, but the underlying chemical mechanism(s) is (are) unknown. We now show that superoxide reduction of Cp Cu is a critical reaction in cellular LDL oxidation. By bathocuproine disulfonate (BCS) binding and by superoxide utilization, we showed that exogenous superoxide reduces a single Cp Cu atom, the same Cu required for LDL oxidation. The Cu atom remained bound to Cp during the redox cycle. Three avenues of evidence showed that vascular cells reduce Cp Cu by a superoxide-dependent process. The 2-fold higher rate of Cp Cu reduction by smooth muscle cells (SMC) compared to endothelial cells (EC) was consistent with their relative rates of superoxide release. Furthermore, Cp Cu reduction by cells was blocked by Cu,Zn superoxide dismutase (SOD1). Finally, the level of superoxide produced by EC and SMC was sufficient to cause the amount of Cu reduction observed. An important role of Cp Cu reduction in LDL oxidation was suggested by results showing that SOD1 inhibited Cp Cu reduction and LDL oxidation by SMC with equal potency, while tumor necrosis factor-alpha stimulated both processes. In summary, these results show that superoxide is a critical cellular reductant of divalent transition metals involved in oxidation, and that protein-bound Cu is a substrate for this reaction. The role of these mechanisms in oxidative processes in vivo has yet to be defined.

  20. Anoxic nitrate reduction coupled with iron oxidation and attenuation of dissolved arsenic and phosphate in a sand and gravel aquifer

    Science.gov (United States)

    Smith, Richard L.; Kent, Douglas B.; Repert, Deborah A.; Böhlke, J. K.

    2017-01-01

    . Additionally, Fe(II)-oxidizing, nitrate-reducing microbial enrichment cultures were obtained from aquifer sediments. Growth experiments with the cultures sequentially produced nitrite and nitrous oxide from nitrate while simultaneously oxidizing Fe(II). Field and culture results suggest that nitrogen oxide reduction and Fe(II) oxidation in the aquifer are a complex interaction of coupled biotic and abiotic reactions. Overall, the results of this study demonstrate that anoxic nitrate-dependent iron oxidation can occur in groundwater; that it could control iron speciation; and that the process can impact the mobility of other chemical species (e.g., phosphate and arsenic) not directly involved in the oxidation-reduction reaction.

  1. Method for catalyzing oxidation/reduction reactions of simple molecules

    Energy Technology Data Exchange (ETDEWEB)

    Bicker, D.; Bonaventura, J.

    1988-06-14

    A method for oxidizing carbon monoxide to carbon dioxide is described comprising: (1) contacting, together, carbon monoxide, a nitrogen-containing chelating agent and water; wherein the chelating agent is at least one member selected from the group consisting of methmeoglobin bound to a support, ferric hemoglobin bound to a support, iron-containing porphyrins bound to a support, and sperm whale myoglobin bound to a support, wherein the support is glass, a natural fiber, a synthetic fiber, a gel, charcoal, carbon ceramic material, a metal oxide, a synthetic polymer, a zeolite, a silica compound of an alumina compound; and (2) obtaining carbon dioxide.

  2. Influence of Na2 CO3 as Additive on Direct Reduction of Boron-bearing Magnetite Concentrate

    Institute of Scientific and Technical Information of China (English)

    Yong-li LI; Jing-kui QU; Guang-ye WEI; Tao QI

    2016-01-01

    Boron-bearing magnetite concentrate is typically characterized by low grade of iron and boron (wTFe=51%-54%,wB2 O3=6%-8%),as well as the close intergrowth of ascharite phase and magnetite phase.A promising technology was proposed to separate iron and boron by coupling the direct reduction of iron oxides and Na activation of boron minerals together.The influence of Na2 CO3 as additive on the direct reduction of boron-bearing magnetite was studied by chemical analysis,kinetic analysis,XRD analysis and SEM analysis.The results showed that the ad-dition of Na2 CO3 not only activated boron minerals,but also reduced the activation energy of the reaction and pro-moted the reduction of iron oxides.Besides,the addition of Na2 CO3 changed the composition and melting point of non-ferrous phase,and then promoted the growth and aggregation of iron grains,which was conducive to the subse-quent magnetic separation.Thus,the coupling of the two processes is advantageous.

  3. Effect of oxidation and catalytic reduction of trace organic contaminants on their activated carbon adsorption.

    Science.gov (United States)

    Schoutteten, Klaas V K M; Hennebel, Tom; Dheere, Ellen; Bertelkamp, Cheryl; De Ridder, David J; Maes, Synthia; Chys, Michael; Van Hulle, Stijn W H; Vanden Bussche, Julie; Vanhaecke, Lynn; Verliefde, Arne R D

    2016-12-01

    The combination of ozonation and activated carbon (AC) adsorption is an established technology for removal of trace organic contaminants (TrOCs). In contrast to oxidation, reduction of TrOCs has recently gained attention as well, however less attention has gone to the combination of reduction with AC adsorption. In addition, no literature has compared the removal behavior of reduction vs. ozonation by-products by AC. In this study, the effect of pre-ozonation vs pre-catalytic reduction on the AC adsorption efficiency of five TrOCs and their by-products was compared. All compounds were susceptible to oxidation and reduction, however the catalytic reductive treatment proved to be a slower reaction than ozonation. New oxidation products were identified for dinoseb and new reduction products were identified for carbamazepine, bromoxynil and dinoseb. In terms of compatibility with AC adsorption, the influence of the oxidative and reductive pretreatments proved to be compound dependent. Oxidation products of bromoxynil and diatrizoic acid adsorbed better than their parent TrOCs, but oxidation products of atrazine, carbamazepine and dinoseb showed a decreased adsorption. The reductive pre-treatment showed an enhanced AC adsorption for dinoseb and a major enhancement for diatrizoic acid. For atrazine and bromoxynil, no clear influence on adsorption was noted, while for carbamazepine, the reductive pretreatment resulted in a decreased AC affinity. It may thus be concluded that when targeting mixtures of TrOCs, a trade-off will undoubtedly have to be made towards overall reactivity and removal of the different constituents, since no single treatment proves to be superior to the other.

  4. Direct observation of the oxygenated species during oxygen reduction on a platinum fuel cell cathode

    OpenAIRE

    Kaya, Sarp; Casalongue, Hernan Sanchez; Viswanathan, Venkatasubramanian ; Miller, Daniel J. ; Friebel, Daniel ; Hansen, Heine A. ; Nørskov, Jens K. ; Nilsson, Anders ; Ogasawara, Hirohito

    2013-01-01

    The performance of polymer electrolyte membrane fuel cells is limited by the reduction at the cathode of various oxygenated intermediates in the four-electron pathway of the oxygen reduction reaction. Here we use ambient pressure X-ray photoelectron spectroscopy, and directly probe the correlation between the adsorbed species on the surface and the electrochemical potential. We demonstrate that, during the oxygen reduction reaction, hydroxyl intermediates on the cathode surface occur in sever...

  5. Oxidation-Reduction Calculations in the Biochemistry Course

    Science.gov (United States)

    Feinman, Richard D.

    2004-01-01

    Redox calculations have the potential to reinforce important concepts in bioenergetics. The intermediacy of the NAD[superscript +]/NADH couple in the oxidation of food by oxygen, for example, can be brought out by such calculations. In practice, students have great difficulty and, even when adept at the calculations, frequently do not understand…

  6. Carbon monoxide-induced reduction and healing of graphene oxide

    NARCIS (Netherlands)

    Narayanan, B.; Weeks, S. L.; Jariwala, B. N.; Macco, B.; Weber, J.; Rathi, S. J.; M. C. M. van de Sanden,; Sutter, P.; Agarwal, S.; Ciobanu, C. V.

    2013-01-01

    Graphene oxide holds promise as a carbon-based nanomaterial that can be produced inexpensively in large quantities. However, its structural and electrical properties remain far from those of the graphene sheets obtained by mechanical exfoliation or by chemical vapor deposition unless efficient reduc

  7. Carbon monoxide-induced reduction and healing of graphene oxide

    NARCIS (Netherlands)

    Narayanan, B.; Weeks, S. L.; Jariwala, B. N.; Macco, B.; Weber, J.; Rathi, S. J.; M. C. M. van de Sanden,; Sutter, P.; Agarwal, S.; Ciobanu, C. V.

    2013-01-01

    Graphene oxide holds promise as a carbon-based nanomaterial that can be produced inexpensively in large quantities. However, its structural and electrical properties remain far from those of the graphene sheets obtained by mechanical exfoliation or by chemical vapor deposition unless efficient reduc

  8. Oxidation and Reduction of Liquid SnPb (60/40) under Ambient and Vacuum Conditions

    DEFF Research Database (Denmark)

    Kuhmann, Jochen Friedrich; Maly, K.; Preuss, A.;

    1998-01-01

    One of the most straightforward approaches to fluxless solder bonding is using vacuum conditions to prevent further oxidation and, where needed, to reduce solder oxides by the use of molecular hydrogen (H-2).(1-3) This study On oxidation and reduction of solder oxides on SnPb (60/40) is aimed...... to provide a better understanding for fluxless solder bonding applications under controlled atmospheric conditions; By means of scanning Auger spectroscopy it is shown, that growth of oxide films on metallic SnPb above the eutectic temperature can be significantly reduced by decreasing the O-2 partial...... at 200 and 250 degrees C is crystalline SnO. For sample preparation, the reduction of the native oxide on eutectic SnPb was carried out successfully using low temperature (250 degrees C) and short heating cycles (2 min). The effectiveness of H-2 to reduce SnO2 at typical soldering parameters (240 degrees...

  9. Mechanism of porcine liver xanthine oxidoreductase mediated N-oxide reduction of cyadox as revealed by docking and mutagenesis studies.

    Directory of Open Access Journals (Sweden)

    Chigang Chen

    Full Text Available Xanthine oxidoreductase (XOR is a cytoplasmic molybdenum-containing oxidoreductase, catalyzing both endogenous purines and exogenous compounds. It is suggested that XOR in porcine hepatocytes catalyzes the N-oxide reduction of quinoxaline 1,4-di-N-oxides (QdNOs. To elucidate the molecular mechanism underlying this metabolism, the cDNA of porcine XOR was cloned and heterologously expressed in Spodoptera frugiperda insect cells. The bovine XOR, showing sequence identity of 91% to porcine XOR, was employed as template for homology modeling. By docking cyadox, a representative compound of QdNOs, into porcine XOR model, eight amino acid residues, Gly47, Asn352, Ser360, Arg427, Asp430, Asp431, Ser1227 and Lys1230, were located at distances of less than 4Å to cyadox. Site-directed mutagenesis was performed to analyze their catalytic functions. Compared with wild type porcine XOR, G47A, S360P, D431A, S1227A, and K1230A displayed altered kinetic parameters in cyadox reduction, similarly to that in xanthine oxidation, indicating these mutations influenced electron-donating process of xanthine before subsequent electron transfer to cyadox to fulfill the N-oxide reduction. Differently, R427E and D430H, both located in the 424-434 loop, exhibited a much lower K(m and a decreased V(max respectively in cyadox reduction. Arg427 may be related to the substrate binding of porcine XOR to cyadox, and Asp430 is suggested to be involved in the transfer of electron to cyadox. This study initially reveals the possible catalytic mechanism of porcine XOR in cyadox metabolism, providing with novel insights into the structure-function relationship of XOR in the reduction of exogenous di-N-oxides.

  10. Study on the influences of reduction temperature on nickel-yttria-stabilized zirconia solid oxide fuel cell anode using nickel oxide-film electrode

    Science.gov (United States)

    Jiao, Zhenjun; Ueno, Ai; Suzuki, Yuji; Shikazono, Naoki

    2016-10-01

    In this study, the reduction processes of nickel oxide at different temperatures were investigated using nickel-film anode to study the influences of reduction temperature on the initial performances and stability of nickel-yttria-stabilized zirconia anode. Compared to conventional nickel-yttria-stabilized zirconia composite cermet anode, nickel-film anode has the advantage of direct observation at nickel-yttria-stabilized zirconia interface. The microstructural changes were characterized by scanning electron microscopy. The reduction process of nickel oxide is considered to be determined by the competition between the mechanisms of volume reduction in nickel oxide-nickel reaction and nickel sintering. Electrochemical impedance spectroscopy was applied to analyze the time variation of the nickel-film anode electrochemical characteristics. The anode performances and microstructural changes before and after 100 hours discharging and open circuit operations were analyzed. The degradation of nickel-film anode is considered to be determined by the co-effect between the nickel sintering and the change of nickel-yttria-stabilized zirconia interface bonding condition.

  11. Electrochemical reduction of nitrous oxide on La1-xSrxFeO3 perovskites

    DEFF Research Database (Denmark)

    Kammer Hansen, Kent

    2010-01-01

    The electrochemical reduction of nitrous oxide and oxygen has been studied on cone-shaped electrodes of La1-xSrxFeO3-delta perovskites in an all solid state cell, using cyclic voltammetry. It was shown that the activity of the La1-xSrxFeO3-delta perovskites for the electrochemical reduction...

  12. High quality reduced graphene oxide flakes by fast kinetically controlled and clean indirect UV-induced radical reduction

    Science.gov (United States)

    Flyunt, Roman; Knolle, Wolfgang; Kahnt, Axel; Halbig, Christian E.; Lotnyk, Andriy; Häupl, Tilmann; Prager, Andrea; Eigler, Siegfried; Abel, Bernd

    2016-03-01

    This work highlights a surprisingly simple and kinetically controlled highly efficient indirect method for the production of high quality reduced graphene oxide (rGO) flakes via UV irradiation of aqueous dispersions of graphene oxide (GO), in which the GO is not excited directly. While the direct photoexcitation of aqueous GO (when GO is the only light-absorbing component) takes several hours of reaction time at ambient temperature (4 h) leading only to a partial GO reduction, the addition of small amounts of isopropanol and acetone (2% and 1%) leads to a dramatically shortened reaction time by more than two orders of magnitude (2 min) and a very efficient and soft reduction of graphene oxide. This method avoids the formation of non-volatile species and in turn contamination of the produced rGO and it is based on the highly efficient generation of reducing carbon centered isopropanol radicals via the reaction of triplet acetone with isopropanol. While the direct photolysis of GO dispersions easily leads to degradation of the carbon lattice of GO and thus to a relatively low electric conductivity of the films of flakes, our indirect photoreduction of GO instead largely avoids the formation of defects, keeping the carbon lattice intact. Mechanisms of the direct and indirect photoreduction of GO have been elucidated and compared. Raman spectroscopy, XPS and conductivity measurements prove the efficiency of the indirect photoreduction in comparison with the state-of-the-art reduction method for GO (hydriodic acid/trifluoroacetic acid). The rapid reduction times and water solvent containing only small amounts of isopropanol and acetone may allow easy process up-scaling for technical applications and low-energy consumption.This work highlights a surprisingly simple and kinetically controlled highly efficient indirect method for the production of high quality reduced graphene oxide (rGO) flakes via UV irradiation of aqueous dispersions of graphene oxide (GO), in which the

  13. Thermodynamic Analysis and Reduction of Bismuth Oxide by Ethanol

    Science.gov (United States)

    Korkmaz, Fatih; Cetinkaya, Senol; Eroglu, Serafettin

    2016-08-01

    In this study, ethanol (C2H5OH) was used as an alternative reducing agent for Bi2O3 because ethanol is renewable, increasingly available, and low in toxicity. Thermodynamic analysis was performed to predict experimental conditions for Bi formation in the Bi2O3-C2H5OH-Ar system at Ar/C2H5OH molar ratio of 10.5. Ar was used as a carrier gas for ethanol. Bi2O3 reduction kinetics was investigated at 600 K to 800 K (327 °C to 527 °C) at Ar flow rate 85 sccm. Ar flow rate was also varied at 600 K and 800 K (327 °C and 527 °C) in order to clarify the mechanism controlling the process. Mass measurements and XRD analyses were carried out to determine the extent of reduction. Fractional conversion increased with time and temperature. Full reduction time decreased from ~180 minutes at 600 K (327 °C) to ~30 minutes at 700 K and 800 K (427 °C and 527 °C). The reduction process was external mass transfer limited ( Q a = 7.2 kJ/mole) above 700 K (427 °C). It was controlled by intrinsic chemical kinetics ( Q a = 54.7 kJ/mole) below 700 K (427 °C). In the mass-transport-controlled regime, the extent of reduction increased with flow rate as predicted by a mass-transport theory. Possible reaction pathways were discussed using the thermodynamic and experimental results.

  14. Removal of PCBs in contaminated soils by means of chemical reduction and advanced oxidation processes.

    Science.gov (United States)

    Rybnikova, V; Usman, M; Hanna, K

    2016-09-01

    Although the chemical reduction and advanced oxidation processes have been widely used individually, very few studies have assessed the combined reduction/oxidation approach for soil remediation. In the present study, experiments were performed in spiked sand and historically contaminated soil by using four synthetic nanoparticles (Fe(0), Fe/Ni, Fe3O4, Fe3 - x Ni x O4). These nanoparticles were tested firstly for reductive transformation of polychlorinated biphenyls (PCBs) and then employed as catalysts to promote chemical oxidation reactions (H2O2 or persulfate). Obtained results indicated that bimetallic nanoparticles Fe/Ni showed the highest efficiency in reduction of PCB28 and PCB118 in spiked sand (97 and 79 %, respectively), whereas magnetite (Fe3O4) exhibited a high catalytic stability during the combined reduction/oxidation approach. In chemical oxidation, persulfate showed higher PCB degradation extent than hydrogen peroxide. As expected, the degradation efficiency was found to be limited in historically contaminated soil, where only Fe(0) and Fe/Ni particles exhibited reductive capability towards PCBs (13 and 18 %). In oxidation step, the highest degradation extents were obtained in presence of Fe(0) and Fe/Ni (18-19 %). The increase in particle and oxidant doses improved the efficiency of treatment, but overall degradation extents did not exceed 30 %, suggesting that only a small part of PCBs in soil was available for reaction with catalyst and/or oxidant. The use of organic solvent or cyclodextrin to improve the PCB availability in soil did not enhance degradation efficiency, underscoring the strong impact of soil matrix. Moreover, a better PCB degradation was observed in sand spiked with extractable organic matter separated from contaminated soil. In contrast to fractions with higher particle size (250-500 and oxidation reactions in soils and understand the impact of soil properties on remediation performance.

  15. Functionalization of cotton fabrics through thermal reduction of graphene oxide

    Science.gov (United States)

    Cai, Guangming; Xu, Zhenglin; Yang, Mengyun; Tang, Bin; Wang, Xungai

    2017-01-01

    Graphene oxide (GO) was in-situ reduced on cotton fabrics by a simple heat treatment, which endowed cotton fabrics with multi-functions. GO was coated on the surface of cotton fabric through a conventional "dip and dry" approach. Reduced graphene oxide (RGO) was obtained from GO in the presence of cotton by heating under the protection of nitrogen. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy were employed to characterize the complexes of RGO and cotton (RGO/cotton). The RGO/cotton fabrics showed good electrical conductivity, surface hydrophobicity and ultraviolet (UV) protection properties. These properties did not deteriorate significantly after repeated fabric bending and washing.

  16. Stepwise Reduction of Immobilized Mono layer Graphene Oxides

    DEFF Research Database (Denmark)

    Petersen, Søren; He, Yudong; Lang, Jiang

    2013-01-01

    Chemically converted graphene is highly relevant for transparent conducting film applications such as display and photovoltaic uses. So far, the major obstacle for realizing the potential has been to fully reduce/deoxygenate the graphene oxide (GO), which is challenging in part due...... to the pronounced aggregation that accompanies deoxygenation of GO in solution. Surface immobilization of monolayered graphene oxide (mGO) in Langmuir-Blodgett (LB) films was investigated as a method to circumvent this problem. Two types of LB films with different density of mGO flakes were prepared, i.e., diluted...... spectroscopy (XPS) along with electrical characterization. XPS measurements confirmed a full conversion into virtually oxygen-free chemically converted graphene. The electrical characterization revealed large variations in the conductivity for single sheets in the diluted LB films, with an average conductivity...

  17. Anoxic nitrate reduction coupled with iron oxidation and attenuation of dissolved arsenic and phosphate in a sand and gravel aquifer

    Science.gov (United States)

    Smith, Richard L.; Kent, Douglas B.; Repert, Deborah A.; Böhlke, J.K.

    2017-01-01

    weeks. Additionally, Fe(II)-oxidizing, nitrate-reducing microbial enrichment cultures were obtained from aquifer sediments. Growth experiments with the cultures sequentially produced nitrite and nitrous oxide from nitrate while simultaneously oxidizing Fe(II). Field and culture results suggest that nitrogen oxide reduction and Fe(II) oxidation in the aquifer are a complex interaction of coupled biotic and abiotic reactions. Overall, the results of this study demonstrate that anoxic nitrate-dependent iron oxidation can occur in groundwater; that it could control iron speciation; and that the process can impact the mobility of other chemical species (e.g., phosphate and arsenic) not directly involved in the oxidation–reduction reaction.

  18. Direct nitrous oxide emissions from rapeseed in Germany

    Science.gov (United States)

    Fuß, Roland; Andres, Monique; Hegewald, Hannes; Kesenheimer, Katharina; Köbke, Sarah; Räbiger, Thomas; Suarez, Teresa; Stichnothe, Heinz; Flessa, Heiner

    2014-05-01

    The production of first generation biofuels has increased over the last decade in Germany. However, there is a strong public and scientific debate concerning ecological impact and sustainability of biofuel production. The EU Renewables Directive requires biofuels to save 35 % of GHG emissions compared to fossil fuels. Starting in 2017, 50 % mitigation of GHG emissions must be achieved. This presents challenges for production of biofuels from rapeseed, which is one of the major renewable resources used for fuel production. Field emissions of nitrous oxide (N2O) and GHG emissions during production of fertilizers contribute strongest to the GHG balance of rapeseed biofuel. Thus, the most promising GHG mitigation option is the optimization of nitrogen fertilization. Since 2012, field trials are conducted on five German research farms to quantify direct GHG emissions. The sites were selected to represent the main rapeseed production regions in Germany as well as climatic regions and soil types. Randomized plot designs were established, which allow monitoring (using manual chambers) impact of fertilization intensity on direct emissions and yield of the typical crop sequence (winter rape - winter wheat - winter barley). The effect of substituting mineral fertilizer with biogas digestate with and without addition of a nitrification inhibitor is also studied. Here we present results from the first cropping season. In 2013, annual direct N2O emissions as well as yield normalized N2O emissions from rape were low. This can be explained with the weather conditions as 2013 was characterized by a cold and long winter with snow until mid spring. As a result, emissions were smaller than predicted by the IPCC emission factors or by the Global Nitrous Oxide Calculator (GNOC). However, emissions still depend on nitrogen input.

  19. Align Ag Nanorods via Oxidation Reduction Growth Using RF-Sputtering

    Directory of Open Access Journals (Sweden)

    Zhan-Shuo Hu

    2012-01-01

    Full Text Available Silver nanorod arrays grew on the individual metallic silver particles after the thermal decomposition of the silver oxides. The formation of silver oxide came from the input of oxygen during sputtering. The subsequent growth of the Ag nanorods started from the single silver grain that originated from the decomposition caused by thermal reduction. This method for oxidation reduction growth used no catalysts and improved the interface effect for the lattice match. Photoluminescence of Ag nanorods was detected at 2.17 eV.

  20. Laser-Scribed Photo-thermal Reduction of Graphene-Oxide for Thin Film Sensor Applications

    OpenAIRE

    Kazemzadeh, Rouzbeh

    2015-01-01

    In this thesis, a cost effective, simple and fast method of reduction of Graphene Oxide thin film is proposed. Graphene oxide is a non-conductive material intrinsically and one of the techniques to convert it to conductive material is using laser beam to remove oxygen groups from its surface, in other words, to reduce it. Laser parameters must be optimized for an effective and successful reduction. Thin film of non-conductive Graphene oxide is converted into conductive thin layer by fast lase...

  1. Selective catalytic reduction of nitrogen oxides with ammonia over microporous zeolite catalysts

    OpenAIRE

    VENNESTROM, PETER NICOLAI RAVNBORG

    2014-01-01

    With increasing legislative demands to remove nitrogen oxides (NOx) from automotive diesel exhaust, new catalyst systems are investigated and intensely studied in industry as well in academia. The most prevailing catalytic method of choice is the selective catalytic reduction (SCR) where non-toxic urea is used as a reductant for practical reasons. Usually urea is stored in a separate tank and once injected into the exhaust system it hydrolyses into the more aggressive reductant NH3 and CO2. ...

  2. Solid Oxide Fuel Cell Cathodes. Unraveling the Relationship Between Structure, Surface Chemistry and Oxygen Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Gopalan, Srikanth [Boston Univ., MA (United States)

    2013-03-31

    In this work we have considered oxygen reduction reaction on LSM and LSCF cathode materials. In particular we have used various spectroscopic techniques to explore the surface composition, transition metal oxidation state, and the bonding environment of oxygen to understand the changes that occur to the surface during the oxygen reduction process. In a parallel study we have employed patterned cathodes of both LSM and LSCF cathodes to extract transport and kinetic parameters associated with the oxygen reduction process.

  3. Direct oxidation of waste vegetable oil in solid-oxide fuel cells

    Science.gov (United States)

    Zhou, Z. F.; Kumar, R.; Thakur, S. T.; Rudnick, L. R.; Schobert, H.; Lvov, S. N.

    Solid-oxide fuel cells with ceria, ceria-Cu, and ceria-Rh anode were demonstrated to generate stable electric power with waste vegetable oil through direct oxidation of the fuel. The only pre-treatment to the fuel was a filtration to remove particulates. The performance of the fuel cell was stable over 100 h for the waste vegetable oil without dilution. The generated power was up to 0.25 W cm -2 for ceria-Rh fuel cell. This compares favorably with previously studied hydrocarbon fuels including jet fuels and Pennsylvania crude oil.

  4. Direct activation of ATM by resveratrol under oxidizing conditions.

    Directory of Open Access Journals (Sweden)

    Ji-Hoon Lee

    Full Text Available Resveratrol has been widely reported to reduce cancer progression in model systems and to selectively induce cell death in transformed cell lines. Many enzymes have been reported to respond to resveratrol in mammalian cells, including the Ataxia-Telangiectasia Mutated (ATM protein kinase that acts in DNA damage recognition, signaling, and repair. Here we investigate the responses of ATM to resveratrol exposure in normal and transformed human cell lines and find that ATM autophosphorylation and substrate phosphorylation is stimulated by resveratrol in a manner that is promoted by reactive oxygen species (ROS. We observe direct stimulatory effects of resveratrol on purified ATM in vitro and find that the catalytic efficiency of the kinase on a model substrate is increased by resveratrol. In the purified system we also observe a requirement for oxidation, as the effect of resveratrol on ATM signaling is substantially reduced by agents that prevent disulfide bond formation in ATM. These results demonstrate that resveratrol effects on ATM are direct, and suggest a mechanism by which the oxidizing environment of transformed cells promotes ATM activity and blocks cell proliferation.

  5. Sequential reduction-oxidation for photocatalytic degradation of tetrabromobisphenol A: Kinetics and intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yaoguang; Lou, Xiaoyi; Xiao, Dongxue; Xu, Lei [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Wang, Zhaohui, E-mail: zhaohuiwang@dhu.edu.cn [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Liu, Jianshe, E-mail: liujianshe@dhu.edu.cn [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Sequential photocatalytic reduction-oxidation degradation of TBBPA was firstly examined. Black-Right-Pointing-Pointer Different atmospheres were found to have significant effect on debromination reaction. Black-Right-Pointing-Pointer A possible sequential photocatalytic reduction-oxidation pathway was proposed. - Abstract: C-Br bond cleavage is considered as a key step to reduce their toxicities and increase degradation rates for most brominated organic pollutants. Here a sequential reduction/oxidation strategy (i.e. debromination followed by photocatalytic oxidation) for photocatalytic degradation of tetrabromobisphenol A (TBBPA), one of the most frequently used brominated flame retardants, was proposed on the basis of kinetic analysis and intermediates identification. The results demonstrated that the rates of debromination and even photodegradation of TBBPA strongly depended on the atmospheres, initial TBBPA concentrations, pH of the reaction solution, hydrogen donors, and electron acceptors. These kinetic data and byproducts identification obtained by GC-MS measurement indicated that reductive debromination reaction by photo-induced electrons dominated under N{sub 2}-saturated condition, while oxidation reaction by photoexcited holes or hydroxyl radicals played a leading role when air was saturated. It also suggested that the reaction might be further optimized for pretreatment of TBBPA-contaminated wastewater by a two-stage reductive debromination/subsequent oxidative decomposition process in the UV-TiO{sub 2} system by changing the reaction atmospheres.

  6. Direct plasma NOx reduction using single surface dielectric barrier discharge

    DEFF Research Database (Denmark)

    Kroushawi, Feisal; Stamate, Eugen

    2014-01-01

    NOx reduction using direct atmospheric barrier discharge in air-NO mixture at different voltages and flow rates is inversigated. Reduction rate of 80% is achieved at 3.18 W/cm2 power density and gas mixture of 20 slm air and 0.006 slm NO. The ozone for NO reduction is produced by a honeycomb...... structured DBD with a total surface of 12.56 cm2. The reduction process is investigated by FTIR spectroscopy, chemiluminsecence, mass spectrometry and optical emission spectroscopy....

  7. Effect of Oxide Level on Pore Formation in A356 Alloy by X-Ray Imaging and Directional Solidification Technology

    Science.gov (United States)

    Liao, Hengcheng; Song, Wan; Wang, Qigui; Zhao, Lei; Fan, Ran

    Effect of oxide level on porosity formation in an A356 alloy was investigated using micro-focus X-ray imaging and directional solidification technology. The increase of oxide level in liquid aluminum was achieved by violently stirring molten metal at elevated temperature. During solidification, the increased oxide content in melt significantly increases the amount of active nucleation sites for porosity and thus raises the nucleation temperature of pores. The fast growth of those early formed pores further restrains the succeeding nucleation operations of new pores in local regions and results in a considerable reduction in pore density. It was also found that the melt with high oxide content shows less dependency of growth rate reduction with local temperature.

  8. Nitrogen oxide reduction strategies for compression ignition engines

    Science.gov (United States)

    Chapman, Elana M.

    2008-05-01

    The scope of this investigation is to explore strategies to reduce NOx emissions from compression ignition engines. Two methods are presented in this collection of studies: (1) NOx reduction accomplished through a change in fuel formulation, specifically through a change in the saturated fuel carbon chains of biodiesel; and (2) NOx reduction accomplished through a mixed mode combustion process utilizing a fumigated fuel and a pilot injection of diesel fuel. In the first study, a light duty diesel engine was used to investigate the change in saturation of a biodiesel fuel and its impact on NOx emissions. Previous studies have shown that a reduction in the iodine value of a biodiesel fuel produces a reduction in NOx emissions. The iodine value of the fuel is reduced through the saturation of the C18 molecules via hydrogenation of biodiesel fuel. Experiments were performed at several speeds and loads without exhaust gas recirculation (EGR), and a NOx reduction with the hydrogenated diesel fuel was observed. For all the modes studied, the NOx emission was higher for the biodiesel and lower for the hydrogenated biodiesel in comparison to the ultra low sulfur diesel (ULSD) fuel. Results from the calculation of the adiabatic flame temperature shows that the results could be explained by the difference in adiabatic flame temperature of the fuel, thus influencing the prompt NOx contribution in addition to the thermal contribution. Since the adiabatic flame temperatures are similar for the hydrogenated biodiesel and the ULSD, yet the NOx reduction with the hydrogenated biodiesel is much lower than the ULSD levels, another explanation for the reduction is suggested: the additional prompt NOx contribution from the change in fuel chemistry. The second study investigated the NOx reductions which could be achieved with a mixed mode combustion process utilizing a fumigated fuel and a pilot injection of diesel fuel. In this research, the fumigated fuel was dimethyl ether (DME) and

  9. Effects of mechanical milling on the carbothermal reduction of oxide of WC/Co hardmetal scrap

    Science.gov (United States)

    Lee, Gil-Geun; Ha, Gook-Hyun

    2016-03-01

    The effects of mechanical milling on the carbothermal reduction of oxidized WC/Co hardmetal scrap with solid carbon were examined. Mixed powders were manufactured by milling the WC/Co hard metal scrap oxide and carbon powder in either a tumbler-ball mill or a planetary-ball mill. The milling type affected the carbothermal reduction of the oxide owing to the differing collision energies (mechanical milling energies) in the mills. The hardmetal scrap oxide powder (WO3, CoWO4) milled at high energy was more greatly reduced and at a lower temperature than that milled at lower mechanical energy. The formation of WC by the carburization reaction with solid carbon reached completion at a lower temperature after higher-energy milling than after lower-energy milling. The WC/Co composite particles synthesized by the combined oxidationmechanical milling-carbothermal reduction process were smaller when the initial powder was milled at higher mechanical energy.

  10. Novel method of screening the oxidation and reduction abilities of photocatalytic materials.

    Science.gov (United States)

    Katayama, K; Takeda, Y; Shimaoka, K; Yoshida, K; Shimizu, R; Ishiwata, T; Nakamura, A; Kuwahara, S; Mase, A; Sugita, T; Mori, M

    2014-04-21

    Two analytical methods for the evaluation of photocatalytic oxidation and reduction abilities were developed using a photocatalytic microreactor; one is product analysis and the other is reaction rate analysis. Two simple organic conversion reactions were selected for the oxidation and reduction. Since the reactions were one-to-one conversions from the reactant species to the product species, the product analysis was simply performed using gas chromatography, and the reactions were monitored in situ in the photocatalytic microreactor using the UV absorption spectra. The partial oxidation and reduction abilities for each functional group can be judged from the yield and selectivity, and the corresponding reaction rate, while the total oxidation ability can be judged from the conversion. We demonstrated the application of these methods for several kinds of visible light photocatalysts.

  11. Electrochemical processing of spent nuclear fuels: An overview of oxide reduction in pyroprocessing technology

    Directory of Open Access Journals (Sweden)

    Eun-Young Choi

    2015-12-01

    Full Text Available The electrochemical reduction process has been used to reduce spent oxide fuel to a metallic form using pyroprocessing technology for a closed fuel cycle in combination with a metal-fuel fast reactor. In the electrochemical reduction process, oxides fuels are loaded at the cathode basket in molten Li2O–LiCl salt and electrochemically reduced to the metal form. Various approaches based on thermodynamic calculations and experimental studies have been used to understand the electrode reaction and efficiently treat spent fuels. The factors that affect the speed of the electrochemical reduction have been determined to optimize the process and scale-up the electrolysis cell. In addition, demonstrations of the integrated series of processes (electrorefining and salt distillation with the electrochemical reduction have been conducted to realize the oxide fuel cycle. This overview provides insight into the current status of and issues related to the electrochemical processing of spent nuclear fuels.

  12. Reduction of Residual Stress in Low Alloy Steel with Magnetic Treatment in Different Directions

    Institute of Scientific and Technical Information of China (English)

    SONG Yanli; HUA Lin; WANG Ben

    2009-01-01

    The behavior that different magnetic treatment directions induce various amounts of welding residual stress reductions in low alloy steel was studied.Reductions of 26%-28% in the lon-gitudinal stress σ_x were obtained when low frequency alternating magnetic treatment was applied perpendicularly to the welding bead,whereas reductions of 20%-21% in σ_x were measured by using the same treatment parameters except that the field direction was applied parallel to the bead.It is proposed that different extent of stress reductions caused by the above two treatment directions is at-tributed primarily to the alteration of the energy absorbed by domains from the external magnetic field,which part of energy can arouse plastic deformation in microstructures by the motion of domain walls.

  13. NO(x) decomposition, storage and reduction over novel mixed oxide catalysts derived from hydrotalcite-like compounds.

    Science.gov (United States)

    Yu, Jun Jie; Cheng, Jie; Ma, Chun Yan; Wang, Hai Lin; Li, Lan Dong; Hao, Zheng Ping; Xu, Zhi Ping

    2009-05-15

    Effective control and removal of nitrogen oxides (NO(x)) emission from vehicles exhausts under lean-burn condition is one of the most important targets in scientific research of environmental protection. A comprehensive introduction of NO(x) storage and reduction (NSR), the most promising lean-NO(x) control technology, is given including the sum-up of NSR materials, catalytic activity and related reaction mechanisms. Emphasis is put on the novel multifunctional NSR catalysts, derived from hydrotalcite-like compounds, with characteristic of simultaneous NO(x) strorage-decomposition-reduction. Finally, future research directions in the area of lean-NO(x) control based on mixed oxide catalysts derived from hydrotalcite-like materials is also proposed.

  14. Study on emissions reduction of DMCC engine with oxidation catalyst

    Institute of Scientific and Technical Information of China (English)

    YAO Chunde; LIU Xibo; WANG Hongfu; LIU Xiaoping; CHENG Chuanhui; WANG Yinshan

    2007-01-01

    A new combustion model diesel/methanol compound combustion (DMCC) is presented,in which methanol is injected into manifold and ignited by certain amount of diesel fuel.The results showed that DMCC remarkably decreased the emission of NOx and the smoke,but increased the emission of HC,CO and PM.However,HC,CO and NOx were dramatically decreased with a catalytic converter,and PM was also decreased compared with that of diesel engine.The testing results illustrated that,combined with oxidation catalyst converter,DMCC could improve engine emissions.

  15. Electrochemical reduction of nitroaromatic compounds by single sheet iron oxide coated electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Li-Zhi, E-mail: lizhi@plen.ku.dk [Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK–1871 Frederiksberg C (Denmark); Hansen, Hans Christian B. [Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK–1871 Frederiksberg C (Denmark); Bjerrum, Morten Jannik [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK–2100 København Ø (Denmark)

    2016-04-05

    Highlights: • Composite layers of single sheet iron oxides were coated on indium tin oxide electrodes. • Single sheet iron oxide is an electro-catalyst for reduction of nitroaromatic compounds in aqueous solution. • The reduction is well explained by a diffusion layer model. • The charge properties of the nitrophenols have an important influence on reduction. • Low-cost iron oxide based materials are promising electro-catalyst for water treatment. - Abstract: Nitroaromatic compounds are substantial hazard to the environment and to the supply of clean drinking water. We report here the successful reduction of nitroaromatic compounds by use of iron oxide coated electrodes, and demonstrate that single sheet iron oxides formed from layered iron(II)-iron(III) hydroxides have unusual electrocatalytic reactivity. Electrodes were produced by coating of single sheet iron oxides on indium tin oxide electrodes. A reduction current density of 10 to 30 μA cm{sup −2} was observed in stirred aqueous solution at pH 7 with concentrations of 25 to 400 μM of the nitroaromatic compound at a potential of −0.7 V vs. SHE. Fast mass transfer favors the initial reduction of the nitroaromatic compound which is well explained by a diffusion layer model. Reduction was found to comprise two consecutive reactions: a fast four-electron first-order reduction of the nitro-group to the hydroxylamine-intermediate (rate constant = 0.28 h{sup −1}) followed by a slower two-electron zero-order reduction resulting in the final amino product (rate constant = 6.9 μM h{sup −1}). The zero-order of the latter reduction was attributed to saturation of the electrode surface with hydroxylamine-intermediates which have a more negative half-wave potential than the parent compound. For reduction of nitroaromatic compounds, the SSI electrode is found superior to metal electrodes due to low cost and high stability, and superior to carbon-based electrodes in terms of high coulombic efficiency and

  16. Mechanistic investigation of Fe(III) oxide reduction by low molecular weight organic sulfur species

    Science.gov (United States)

    Eitel, Eryn M.; Taillefert, Martial

    2017-10-01

    Low molecular weight organic sulfur species, often referred to as thiols, are known to be ubiquitous in aquatic environments and represent important chemical reductants of Fe(III) oxides. Thiols are excellent electron shuttles used during dissimilatory iron reduction, and in this capacity could indirectly affect the redox state of sediments, release adsorbed contaminants via reductive dissolution, and influence the carbon cycle through alteration of bacterial respiration processes. Interestingly, the reduction of Fe(III) oxides by thiols has not been previously investigated in environmentally relevant conditions, likely due to analytical limitations associated with the detection of thiols and their oxidized products. In this study, a novel electrochemical method was developed to simultaneously determine thiol/disulfide pair concentrations in situ during the reduction of ferrihydrite in batch reactors. First order rate laws with respect to initial thiol concentration were confirmed for Fe(III) oxyhydroxide reduction by four common thiols: cysteine, homocysteine, cysteamine, and glutathione. Zero order was determined for both Fe(III) oxyhydroxide and proton concentration at circumneutral pH. A kinetic model detailing the molecular mechanism of the reaction was optimized with proposed intermediate surface structures. Although metal oxide overall reduction rate constants were inversely proportional to the complexity of the thiol structure, the extent of metal reduction increased with structure complexity, indicating that surface complexes play a significant role in the ability of these thiols to reduce iron. Taken together, these results demonstrate the importance of considering the molecular reaction mechanism at the iron oxide surface when investigating the potential for thiols to act as electron shuttles during dissimilatory iron reduction in natural environments.

  17. The Nanostructuring of Atomically Flat Ru(0001) upon Oxidation and Reduction

    Science.gov (United States)

    Goriachko, A.; Over, H.

    2016-12-01

    The O/Ru(0001) system is widely studied due to its rich phase variety of various stoichiometry and atomic arrangements, including the formation of a RuO2/Ru(0001) oxide layer. Apart from homogeneous ruthenium surfaces in certain oxidation states, also strongly heterogeneous surfaces can exist due to oxidation state's variation at the nanoscale. We report on a scanning tunneling microscopy (STM) study of the nanostructuring of the oxidized Ru(0001) surface as a result of its interaction with molecular oxygen at elevated temperatures and subsequent reduction of a resulting RuO2 film by CO or HCl molecules from the gas phase in high-vacuum environment.

  18. Reduction of iron-oxide-carbon composites: part II. Rates of reduction of composite pellets in a rotary hearth furnace simulator

    Energy Technology Data Exchange (ETDEWEB)

    Halder, S.; Fruehan, R.J. [Praxair Inc., Tonawanda, NY (United States). Praxair Technological Center

    2008-12-15

    A new ironmaking concept is being proposed that involves the combination of a rotary hearth furnace (RHF) with an iron-bath smelter. The RHF makes use of iron-oxide-carbon composite pellets as the charge material and the final product is direct-reduced iron (DRI) in the solid or molten state. This part of the research includes the development of a reactor that simulated the heat transfer in an RHF. The external heat-transport and high heating rates were simulated by means of infrared (IR) emitting lamps. The reaction rates were measured by analyzing the off-gas and computing both the amount of CO and CO{sub 2} generated and the degree of reduction. The reduction times were found to be comparable to the residence times observed in industrial RHFs. Both artificial ferric oxide (PAH) and naturally occurring hematite and taconite ores were used as the sources of iron oxide. Coal char and devolatilized wood charcoal were the reductants. Wood charcoal appeared to be a faster reductant than coal char. However, in the PAH-containing pellets, the reverse was found to be true because of heat-transfer limitations. For the same type of reductant, hematite-containing pellets were observed to reduce faster than taconite-containing pellets because of the development of internal porosity due to cracking and fissure formation during the Fe2O{sub 3}-to-Fe3O{sub 4} transition. This is, however, absent during the reduction of taconite, which is primarily Fe3O{sub 4}. The PAH-wood-charcoal pellets were found to undergo a significant amount of swelling at low-temperature conditions, which impeded the external heat transport to the lower layers. If the average degree of reduction targeted in an RHF is reduced from 95 to approximately 70 pct by coupling the RHF with a bath smelter, the productivity of the RHF can be enhanced 1.5 to 2 times. The use of a two- or three-layer bed was found to be superior to that of a single layer, for higher productivities.

  19. Reduction of Iron-Oxide-Carbon Composites: Part II. Rates of Reduction of Composite Pellets in a Rotary Hearth Furnace Simulator

    Science.gov (United States)

    Halder, S.; Fruehan, R. J.

    2008-12-01

    A new ironmaking concept is being proposed that involves the combination of a rotary hearth furnace (RHF) with an iron-bath smelter. The RHF makes use of iron-oxide-carbon composite pellets as the charge material and the final product is direct-reduced iron (DRI) in the solid or molten state. This part of the research includes the development of a reactor that simulated the heat transfer in an RHF. The external heat-transport and high heating rates were simulated by means of infrared (IR) emitting lamps. The reaction rates were measured by analyzing the off-gas and computing both the amount of CO and CO2 generated and the degree of reduction. The reduction times were found to be comparable to the residence times observed in industrial RHFs. Both artificial ferric oxide (PAH) and naturally occurring hematite and taconite ores were used as the sources of iron oxide. Coal char and devolatilized wood charcoal were the reductants. Wood charcoal appeared to be a faster reductant than coal char. However, in the PAH-containing pellets, the reverse was found to be true because of heat-transfer limitations. For the same type of reductant, hematite-containing pellets were observed to reduce faster than taconite-containing pellets because of the development of internal porosity due to cracking and fissure formation during the Fe2O3-to-Fe3O4 transition. This is, however, absent during the reduction of taconite, which is primarily Fe3O4. The PAH-wood-charcoal pellets were found to undergo a significant amount of swelling at low-temperature conditions, which impeded the external heat transport to the lower layers. If the average degree of reduction targeted in an RHF is reduced from 95 to approximately 70 pct by coupling the RHF with a bath smelter, the productivity of the RHF can be enhanced 1.5 to 2 times. The use of a two- or three-layer bed was found to be superior to that of a single layer, for higher productivities.

  20. The copper recovery from cupric oxide catalysts by plasma reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Imris, I.; Klenovcanova, A. [Technical Univ. of Kosice, Kosice (Slovakia). Dept. of Power Engineering

    2007-07-01

    A plasma reduction process was used to recover copper from cupric oxide catalysts. Two types of plasma reduction smelting tests were conducted to verify the thermodynamic calculations. The plasma reactor consisted of a cylindrical steel shell lined with a castable alumina and a graphite crucible. Cupric oxide catalyst ESM 461 was mixed with stoichiometric amounts of carbon reductant and a 10 per cent addition of calcium oxide flux. Results of the experimental tests and the thermodynamic analysis showed that the copper can be extracted from cupric oxide using the plasma reduction process. Copper recovery was limited by physico-chemical copper losses. Copper oxide solubility was relatively high, so that copper recovery was low in their first series of plasma tests. The addition of calcium oxide flux improved copper recovery rates when dicalcium silicate was formed in the slag. The offgas samples indicated that concentrations of carbon monoxide (CO) in the gas phase was very high. It was concluded that the process is both commercially feasible and does not produce liquid or solid wastes. 7 refs., 2 tabs., 4 figs.

  1. Effects of Basicity and MgO in Slag on the Behaviors of Smelting Vanadium Titanomagnetite in the Direct Reduction-Electric Furnace Process

    Directory of Open Access Journals (Sweden)

    Tao Jiang

    2016-05-01

    Full Text Available The effects of basicity and MgO content on reduction behavior and separation of iron and slag during smelting vanadium titanomagnetite by electric furnace were investigated. The reduction behaviors affect the separation of iron and slag in the direct reduction-electric furnace process. The recovery rates of Fe, V, and Ti grades in iron were analyzed to determine the effects of basicity and MgO content on the reduction of iron oxides, vanadium oxides, and titanium oxides. The chemical compositions of vanadium-bearing iron and main phases of titanium slag were detected by XRF and XRD, respectively. The results show that the higher level of basicity is beneficial to the reduction ofiron oxides and vanadium oxides, and titanium content dropped in molten iron with the increasing basicity. As the content of MgO increased, the recovery rate of Fe increased slightly but the recovery rate of V increased considerably. The grades of Ti in molten iron were at a low level without significant change when MgO content was below 11%, but increased as MgO content increased to 12.75%. The optimum conditions for smelting vanadium titanomagnetite were about 11.38% content of MgO and quaternary basicity was about 1.10. The product, vanadium-bearing iron, can be applied in the converter steelmaking process, and titanium slag containing 50.34% TiO2 can be used by the acid leaching method.

  2. Possible domestication of uranium oxides using biological assistance reduction

    Directory of Open Access Journals (Sweden)

    Slah Hidouri

    2017-01-01

    Full Text Available Uranium has been defined in material research engineering field as one of the most energetic radioactive elements in the entire Mendeleev periodic table. The manipulation of uranium needs higher theories and sophisticated apparatus even in nuclear energy extraction or in many other chemical applications. Above the nuclear exploitation level, the chemical conventional approaches used, require a higher temperature and pressure to control the destination of ionic form. However, it has been discovered later that at biological scale, the manipulation of this actinide is possible under friendly conditions. The review summarizes the relevant properties of uranium element and a brief characterization of nanoparticles, based on some structural techniques. These techniques reveal the common link between chemical approaches and biological assistance in nanoparticles. Also, those biological entities have been able to get it after reduction. Uranium is known for its ability to destroy ductile materials. So, if biological cell can really reduce uranium, then how does it work?

  3. Cerium extraction by metallothermic reduction using cerium oxide powder injection

    Institute of Scientific and Technical Information of China (English)

    J.S. Luna A; A. Flores V; R. Mu(n)iz V; A.F. Fuentes; J. Torres; N. Rodríuez R; J.C. Ortiz; P.Orozco

    2011-01-01

    This work presented the feasibility of cerium recovery by Al-Mg alloy through the metallothermic reduction of CeO2 to obtain a master alloy Al-4%Ce. The master alloy obtained in this investigation was for the grain refinement and modification of Al-Si alloys. The reagent was incorporated into a molten alloy using the submerged powder injection technique, and metallic samples were obtained during injection. Chemical and microstructural analyses (by inductively coupled plasma (ICP) and scanning electron microscopy (SEM), respectively) confirmed the possibility of Ce uptake in the bath (0 to 4 wt.%), as CeO2 was reduced through metallothermic reactions in the molten alloys.Based on the characterization of reaction products, the sequence of the reaction was proposed.

  4. Structural Changes Occuring During the Direct Reduction of Attepe Iron Ore

    Directory of Open Access Journals (Sweden)

    Nesibe Ort

    2011-03-01

    Full Text Available At present, most of the World's iron (over 95 % is produced in blast furnaces where it is essential to use high grade coking coal which is in great demand, scarce and very expensive. In addition, the building of blast furnaces requires huge capital investments and because of their large sizes they are not flexible for limited operations. These led, since 1950s to the development of direct reduction processes which have reached a worldwide production of 60 million tons per annum. The iron produced by direct reduction can be used directly as raw material in electric arc furnaces as a replacement of scrap, thus increasing the steel quality. The fact that Turkey imports around 15 million tons of scrap per year for steel production, indicates alone the importance of investigation of suitability of domestic iron ores to the direct reduction. Since the direct reduction processes involve typical gas-solid reactions, the structure of iron ore and structural changes taking place during reaction within the solid phase, have great impact on process kinetics. This study therefore, deals with the changes observed before (i.e. during preheating and during reduction in the surface area and porosity of Attepe iron ore.

  5. In-Situ Optical Studies of Oxidation/Reduction Kinetics on SOFC Cermet Anodes

    Science.gov (United States)

    2010-12-28

    Fuel Cells " Ann. Rev. Anal. Chem., 3 151-174 (2010). 2. B. C. Eigenbrodt1, M. B. Pomfret, D. A. Steinhurst, J. C. Owrutsky and R. A. Walker "Direct...in situ optical studies of solid oxide fuel cells operating with methanol and methane" J. Phys. Chem. C available online at ASAP. (Content from...Mapping of Surface Electrolyte Oxide Concentration in Solid Oxide Fuel Cells " submitted to Analytical Methods, accepted pending revisions. 4. J. D

  6. Reduction and Oxidation of Copper Oxide Thin Films and Thermal Stability Issues in Copper-Based Metallization.

    Science.gov (United States)

    Li, Jian

    This thesis investigates the oxidation and reduction of Cu-oxides and thermal induced reactions of Cu with metals. The combination of ^{16}O( alpha,alpha)^{16}O oxygen resonance and transmission electron microscopy (TEM) provides an effective method of studying the oxidation and reduction of copper oxide thin films. A discontinuous morphology of grain growth of Cu_2O in found in the CuO matrix during reduction. The migration of the Cu_2O-CuO phase boundary is induced by oxygen diffusion along the moving boundary. Grain growth is the dominant process in the transformation from CuO to Cu_2O; nucleation is the dominant process in the reverse transformation, i.e. from Cu_2O to CuO. The reduction and oxidation of copper oxides are asymmetrical; the latter is significantly faster. The metastable phase Cu _4O_3 was formed by ion milling CuO. Carbon and refractory metals such as Ti or Zr can enhance the reduction rate of CuO. Three topics relating to thermal stability issues in Cu-based metallization were investigated: (1) texturing in electroless copper films on epitaxial copper seed layers; (2) predicting first phase formation in Cu/metal bilayer structures; and (3) encapsulation of Cu fine line structures with TiN. (100)- and (111)-textured copper layers were deposited by electroless plating on copper seed layers grown epitaxially on Si (100) and Si (111) substrates, respectively. (111) -textured copper films are more oxidation-resistant. Rutherford backscattering spectrometry (RBS) and in situ transmission electron microscopy (TEM) were used to determine phase formation in Cu-M (M = Ti, Zr, Mg, Sb, Pd and Pt) bilayer systems. An effective heat of formation rule was employed to predict first phase formation in these systems. A TiN-encapsulated copper structure was made by annealing a Cu-10at%Ti alloy film evaporated on a SiO _2/Si(100) substrate at 550^ circC in an NH_3 ambient. Fast heating rates (70^circC/min.) to 550^circC can effectively suppress the formation of Cu

  7. Ferricytochrome (c) directly oxidizes aminoacetone to methylglyoxal, a catabolite accumulated in carbonyl stress.

    Science.gov (United States)

    Sartori, Adriano; Mano, Camila M; Mantovani, Mariana C; Dyszy, Fábio H; Massari, Júlio; Tokikawa, Rita; Nascimento, Otaciro R; Nantes, Iseli L; Bechara, Etelvino J H

    2013-01-01

    Age-related diseases are associated with increased production of reactive oxygen and carbonyl species such as methylglyoxal. Aminoacetone, a putative threonine catabolite, is reportedly known to undergo metal-catalyzed oxidation to methylglyoxal, NH4(+) ion, and H2O2 coupled with (i) permeabilization of rat liver mitochondria, and (ii) apoptosis of insulin-producing cells. Oxidation of aminoacetone to methylglyoxal is now shown to be accelerated by ferricytochrome c, a reaction initiated by one-electron reduction of ferricytochrome c by aminoacetone without amino acid modifications. The participation of O2(•-) and HO (•) radical intermediates is demonstrated by the inhibitory effect of added superoxide dismutase and Electron Paramagnetic Resonance spin-trapping experiments with 5,5'-dimethyl-1-pyrroline-N-oxide. We hypothesize that two consecutive one-electron transfers from aminoacetone (E0 values = -0.51 and -1.0 V) to ferricytochrome c (E0 = 0.26 V) may lead to aminoacetone enoyl radical and, subsequently, imine aminoacetone, whose hydrolysis yields methylglyoxal and NH4(+) ion. In the presence of oxygen, aminoacetone enoyl and O2(•-) radicals propagate aminoacetone oxidation to methylglyoxal and H2O2. These data endorse the hypothesis that aminoacetone, putatively accumulated in diabetes, may directly reduce ferricyt c yielding methylglyoxal and free radicals, thereby triggering redox imbalance and adverse mitochondrial responses.

  8. Direct versus indirect electrochemical oxidation of pesticide polluted drainage water containing sodium chloride

    DEFF Research Database (Denmark)

    Muff, Jens; Erichsen, Rasmus; Damgaard, Christian

    2008-01-01

    Drainage water from a depot of chemical waste, polluted with a mixture of organophosphates and degradation products was treated by a direct as well as an indirect electrochemical method using a Ti/Pt-Ir anode and Stainless Steel 304 cathode. With a concentration of 0.7%, sodium chloride...... the treatment. Indirect electrochemical treatment, where a highly oxidized brine solution was added to the drainage water, revealed immediately reduction in COD, and similar to the direct treatment, degradation of all of the pesticide pollutants was obtained except for the O,O,O-triethyl-phosphoric acid...... concentrations. Analyses of the actual pollutants, Me-Parathion, parathion, malathion and degradation products, confirmed that the concentrations of all initial pollutants were eliminated during the treatment. The only exception was O,O,O-triethyl-phosphoric acid, a degradation product which was formed during...

  9. A novel copper-catalyzed reductive coupling of N-tosylhydrazones with H-phosphorus oxides.

    Science.gov (United States)

    Wu, Lei; Zhang, Xio; Chen, Qing-Qing; Zhou, An-Kun

    2012-10-21

    We report here a novel C(sp(3))-P bonds formation via copper-catalyzed reductive coupling of N-tosylhydrazones with H-phosphorus oxides. A variety of aliphatic and aromatic substrates bearing electron-rich and electron-deficient substituents affords phosphine oxide derivatives with moderate to good yields. This work suggests a new transformation of aldehydes/ketones via N-tosylhydrazones to organophosphorus compounds.

  10. Sources of conductance changes during bacterial reduction of trimethylamine oxide to trimethylammonium in phosphate buffer.

    Science.gov (United States)

    Owens, J D; Miskin, D R; Wacher-Viveros, M C; Benge, L C

    1985-06-01

    The sources of conductance changes during reduction of trimethylamine oxide to trimethylamine by Escherichia coli with formate as electron donor and in the presence of phosphate buffer were investigated. Theoretical considerations and experimental results suggest that the major source of conductance change is the conversion of dihydrogen phosphate to hydrogen phosphate. This transformation contributes almost twice as much to the total conductance change as does the conversion of uncharged trimethylamine oxide to charged trimethylammonium.

  11. Recent progress and perspectives in the photocatalytic CO2 reduction of Ti-oxide-based nanomaterials

    Science.gov (United States)

    Sohn, Youngku; Huang, Weixin; Taghipour, Fariborz

    2017-02-01

    The conversion of CO2 with H2O to valuable chemicals and fuels is a new solution to current environmental and energy problems, and the high energy barrier of these reactions can be overcome by the input of solar and electrical energy. However, the reduction efficiencies and selectivities of these reactions are insufficient for practical use, and significant effort and strategy are required to overcome the many obstacles preventing the large-scale application of photocatalytic CO2 reduction. This article reviews recent progress in CO2 reduction using titanium oxide-based materials and various strategic factors for increasing photocatalytic efficiency. This article also highlights non-titanium-oxide catalysts, the photoelectrocatalytic reduction of CO2, and other recent review articles concerning the recycling of CO2 to value-added carbon compounds.

  12. Catalytic reduction of nitric oxide with carbon monoxide on copper-cobalt oxides supported on nano-titanium dioxide.

    Science.gov (United States)

    Chen, Xia; Zhang, Junfeng; Huang, Yan; Tong, Zhiquan; Huang, Ming

    2009-01-01

    A series of copper-cobalt oxides supported on nano-titanium dioxide were prepared for the reduction of nitric oxide with carbon monoxide and characterized using techniques such as XRD, BET and TPR. Catalyst CuCoOx/TiO2 with Cu/Co molar ratio of 1/2, Cu-Co total loading of 30% at the calcination temperature of 350 degrees C formed CuCo2O4 spinel and had the highest activity. NO conversion reached 98.9% at 200 degrees C. Mechanism of the reduction was also investigated, N2O was mainly yielded below 100 degrees C, while N2 was produced instead at higher temperature. O2 was supposed to accelerate the reaction between NOx and CO for its oxidation of NO to give more easily reduced NO2, but the oxidation of CO by O2 to CO2 decreased the speed of the reaction greatly. Either SO2 or H2O had no adverse impact on the activity of NO reduction; however, in the presence of both SO2 and H2O, the catalyst deactivated quickly.

  13. Mechanism of sodium chloride in promoting reduction of high-magnesium low-nickel oxide ore.

    Science.gov (United States)

    Zhou, Shiwei; Wei, Yonggang; Li, Bo; Wang, Hua; Ma, Baozhong; Wang, Chengyan

    2016-07-04

    Sodium chloride has been proved that it is an effective promoter for the reduction of high-magnesium, low-nickel oxide ore. The aim of current work is to clarify the promotion behavior of sodium chloride in the roasting reduction process. The influence of moisture on the reduction of ore in the presence of sodium chloride is studied to get clear comprehension of promotion process. In the presence of moisture, the HCl is produced by pyrohydrolysis of sodium chloride for chlorinating nickel and iron oxides, moreover, interactions between metallic oxides and sodium chloride are also a way for chlorination at high temperature (>802 °C); subsequently, the metal chloride would be reduced by reductant. In the absence of moisture, the magnetic separation results show that the recoveries of iron and nickel have a significant increase; moreover, olivine structure would be destroyed gradually with the increase of roasting temperature in the action of sodium chloride, and the sodium chloride existed in high-magnesium, low-nickel oxide ore could make the NiO isolate from NiO-bearing minerals. The NiO reacts with Fe2O3 at high temperature to form NiFe2O4, which is conductive to the formation of Ni-Fe alloy during the reduction process.

  14. Reduction of graphene oxide to graphene, A study of changes in the atomic structure

    Science.gov (United States)

    Mittal, A.; Wagner, A.; Mattevi, C.; Chov, A.; Liao, K.; Macosko, C.; Chhowalla, M.; Mkhoyan, K. A.

    2012-02-01

    An economic method for large scale production of graphene is based on exfoliation of graphite into 1-atom thick sheets by oxidation, creating graphene oxide (GO) and subsequent reduction of GO into graphene. Reduced GO sheets approach the highly desired properties of graphene, such as electrical conductivity and mechanical strength, to various degrees, but not completely. To understand why, we must understand the nanostructure of the sheets. Different methods of reduction result in products that are similar to graphene, but these products retain some oxidized areas or contain regions with sp^3 bonded carbon. The concentration and distribution of these defects on the reduced GO sheet affect the properties of the 2D material. Here, we have characterized the atomic structure of GO and reduced GO via high resolution transmission electron microscopy, electron diffraction, and electron energy loss spectroscopy. Spectroscopic data taken during thermal reduction of GO shows changes in the fine structure of carbon K-edge as the carbon changes from an oxidized form to elemental amorphous carbon to graphite like form, clearly delineating the process of reduction of GO to graphene. Products of several other reduction methods are also characterized revealing information on electronic environment surrounding carbon atoms, distribution of crystalline areas, and oxygen removal from GO.

  15. Fe(III) oxides accelerate microbial nitrate reduction and electricity generation by Klebsiella pneumoniae L17.

    Science.gov (United States)

    Liu, Tongxu; Li, Xiaomin; Zhang, Wei; Hu, Min; Li, Fangbai

    2014-06-01

    Klebsiella pneumoniae L17 is a fermentative bacterium that can reduce iron oxide and generate electricity under anoxic conditions, as previously reported. This study reveals that K. pneumoniae L17 is also capable of dissimilatory nitrate reduction, producing NO2(-), NH4(+), NO and N2O under anoxic conditions. The presence of Fe(III) oxides (i.e., α-FeOOH, γ-FeOOH, α-Fe2O3 and γ-Fe2O3) significantly accelerates the reduction of nitrate and generation of electricity by K. pneumoniae L17, which is similar to a previous report regarding another fermentative bacterium, Bacillus. No significant nitrate reduction was observed upon treatment with Fe(2+) or α-FeOOH+Fe(2+), but a slight facilitation of nitrate reduction and electricity generation was observed upon treatment with L17+Fe(2+). This result suggests that aqueous Fe(II) or mineral-adsorbed Fe(II) cannot reduce nitrate abiotically but that L17 can catalyze the reduction of nitrate and generation of electricity in the presence of Fe(II) (which might exist as cell surface-bound Fe(II)). To rule out the potential effect of Fe(II) produced by L17 during microbial iron reduction, treatments with the addition of TiO2 or Al2O3 instead of Fe(III) oxides also exhibited accelerated microbial nitrate reduction and electricity generation, indicating that cell-mineral sorption did account for the acceleration effect. However, the acceleration caused by Fe(III) oxides is only partially attributed to the cell surface-bound Fe(II) and cell-mineral sorption but may be driven by the iron oxide conduction band-mediated electron transfer from L17 to nitrate or an electrode, as proposed previously. The current study extends the diversity of bacteria of which nitrate reduction and electricity generation can be facilitated by the presence of iron oxides and confirms the positive role of Fe(III) oxides on microbial nitrate reduction and electricity generation by particular fermentative bacteria in anoxic environments. Copyright

  16. Mercury mobilization and speciation linked to bacterial iron oxide and sulfate reduction: A column study to mimic reactive transfer in an anoxic aquifer

    Science.gov (United States)

    Hellal, Jennifer; Guédron, Stéphane; Huguet, Lucie; Schäfer, Jörg; Laperche, Valérie; Joulian, Catherine; Lanceleur, Laurent; Burnol, André; Ghestem, Jean-Philippe; Garrido, Francis; Battaglia-Brunet, Fabienne

    2015-09-01

    Mercury (Hg) mobility and speciation in subsurface aquifers is directly linked to its surrounding geochemical and microbial environment. The role of bacteria on Hg speciation (i.e., methylation, demethylation and reduction) is well documented, however little data is available on their impact on Hg mobility. The aim of this study was to test if (i) Hg mobility is due to either direct iron oxide reduction by iron reducing bacteria (IRB) or indirect iron reduction by sulfide produced by sulfate reducing bacteria (SRB), and (ii) to investigate its subsequent fate and speciation. Experiments were carried out in an original column setup combining geochemical and microbiological approaches that mimic an aquifer including an interface of iron-rich and iron depleted zones. Two identical glass columns containing iron oxides spiked with Hg(II) were submitted to (i) direct iron reduction by IRB and (ii) to indirect iron reduction by sulfides produced by SRB. Results show that in both columns Hg was leached and methylated during the height of bacterial activity. In the column where IRB are dominant, Hg methylation and leaching from the column was directly correlated to bacterial iron reduction (i.e., FeII release). In opposition, when SRB are dominant, produced sulfide induced indirect iron oxide reduction and rapid adsorption of leached Hg (or produced methylmercury) on neoformed iron sulfides (e.g., Mackinawite) or its precipitation as HgS. At the end of the SRB column experiment, when iron-oxide reduction was complete, filtered Hg and Fe concentrations increased at the outlet suggesting a leaching of Hg bound to FeS colloids that may be a dominant mechanism of Hg transport in aquifer environments. These experimental results highlight different biogeochemical mechanisms that can occur in stratified sub-surface aquifers where bacterial activities play a major role on Hg mobility and changes in speciation.

  17. Nanophase transition metal oxides show large thermodynamically driven shifts in oxidation-reduction equilibria.

    Science.gov (United States)

    Navrotsky, Alexandra; Ma, Chengcheng; Lilova, Kristina; Birkner, Nancy

    2010-10-08

    Knowing the thermodynamic stability of transition metal oxide nanoparticles is important for understanding and controlling their role in a variety of industrial and environmental systems. Using calorimetric data on surface energies for cobalt, iron, manganese, and nickel oxide systems, we show that surface energy strongly influences their redox equilibria and phase stability. Spinels (M(3)O(4)) commonly have lower surface energies than metals (M), rocksalt oxides (MO), and trivalent oxides (M(2)O(3)) of the same metal; thus, the contraction of the stability field of the divalent oxide and expansion of the spinel field appear to be general phenomena. Using tabulated thermodynamic data for bulk phases to calculate redox phase equilibria at the nanoscale can lead to errors of several orders of magnitude in oxygen fugacity and of 100 to 200 kelvin in temperature.

  18. SCR atmosphere induced reduction of oxidized mercury over CuO-CeO2/TiO2 catalyst.

    Science.gov (United States)

    Li, Hailong; Wu, Shaokang; Wu, Chang-Yu; Wang, Jun; Li, Liqing; Shih, Kaimin

    2015-06-16

    CuO-CeO2/TiO2 (CuCeTi) catalyst synthesized by a sol-gel method was employed to investigate mercury conversion under a selective catalytic reduction (SCR) atmosphere (NO, NH3 plus O2). Neither NO nor NH3 individually exhibited an inhibitive effect on elemental mercury (Hg(0)) conversion in the presence of O2. However, Hg(0) conversion over the CuCeTi catalyst was greatly inhibited under SCR atmosphere. Systematic experiments were designed to investigate the inconsistency and explore the in-depth mechanisms. The results show that the copresence of NO and NH3 induced reduction of oxidized mercury (Hg(2+), HgO in this study), which offset the effect of catalytic Hg(0) oxidation, and hence resulted in deactivation of Hg(0) conversion. High NO and NH3 concentrations with a NO/NH3 ratio of 1.0 facilitated Hg(2+) reduction and therefore lowered Hg(0) conversion. Hg(2+) reduction over the CuCeTi catalyst was proposed to follow two possible mechanisms: (1) direct reaction, in which NO and NH3 react directly with HgO to form N2 and Hg(0); (2) indirect reaction, in which the SCR reaction consumed active surface oxygen on the CuCeTi catalyst, and reduced species on the CuCeTi catalyst surface such as Cu2O and Ce2O3 robbed oxygen from adjacent HgO. Different from the conventionally considered mechanisms, that is, competitive adsorption responsible for deactivation of Hg(0) conversion, this study reveals that oxidized mercury can transform into Hg(0) under SCR atmosphere. Such knowledge is of fundamental importance in developing efficient and economical mercury control technologies for coal-fired power plants.

  19. Fabrication and Characteristics of Reduced Graphene Oxide Produced with Different Green Reductants.

    Science.gov (United States)

    Xu, Changyan; Shi, Xiaomei; Ji, An; Shi, Lina; Zhou, Chen; Cui, Yunqi

    2015-01-01

    There has been an upsurge of green reductants for the preparation of graphene materials taking consideration of human health and the environment in recent years. In this paper, reduced graphene oxides (RGOs) were prepared by chemical reduction of graphene oxide (GO) with three green reductants, L-ascorbic acid (L-AA), D-glucose (D-GLC) and tea polyphenol (TP), and comparatively characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectra, Raman spectra and electrical conductivity analysis. Results showed that all these three reductants were effective to remove oxygen-containing functional groups in GO and restore the electrical conductivity of the obtained RGO. The RGO sample with L-ascorbic acid as a reductant and reduced with the existence of ammonia had the highest electrical conductivity (9.8 S·cm(-1)) among all the obtained RGO samples. The mechanisms regarding to the reduction of GO and the dispersion of RGO in water were also proposed. It is the good dispersibility of reduced graphene oxide in water that will facilitate its further use in composite materials and conductive ink.

  20. Tuning microstructure and surface chemistry of reduced graphene oxide by mild reduction

    Institute of Scientific and Technical Information of China (English)

    冷娴; 刘如铁; 邹俭鹏; 熊翔; 何捍卫

    2016-01-01

    Reduced graphene oxide (RGO) sheets with varied contents and types of oxygenated groups were synthesized by Hummers treatment of natural graphite powders followed by different nontoxic and mild reduction methods, which include thermal and chemical reduction with ethylene glycol, KOH and Fe powder. The changes in microstructure and surface chemistry of RGOs were extensively characterized by SEM, TEM, AFM, XRD, XPS and Raman spectrum. The results show that significant exfoliation occurs during oxidation and is retained in reduction processes, along with the formation of curled wavy morphology. Compared with larged spacing (0.852 nm) of graphene oxide (GO), the (002) plane distance decreases to 0.358−0.384 nm of RGOs, indicating efficient tuning of surface functionalities through mild reduction methods. TheID/IG ratio of RGOs is about 1.0−1.15, indicating that reconstructed sp2 domains have smaller sizes and larger quantity. The content of sp2 bonded C in GO (36.93%, molar fraction) increases to 45.48%−72.92% (molar fraction) in RGOs, along with a drastic decrease in hydroxyl and epoxy and minor changes in carbonyl and carboxyl. Thermal reduction or chemical reduction produces RGOs with residual functionalities, which may render different chemical activity and is desirable in various applications.

  1. Mechanisms for chelator stimulation of microbial Fe(III) -oxide reduction

    Science.gov (United States)

    Lovley, D.R.; Woodward, J.C.

    1996-01-01

    The mechanisms by which nitrilotriacetic acid (NTA) stimulated Fe(III) reduction in sediments from a petroleum-contaminated aquifer were investigated in order to gain insight into how added Fe(III) chelators stimulate the activity of hydrocarbon-degrading, Fe(III)-reducing microorganisms in these sediments, and how naturally occurring Fe(III) chelators might promote Fe(III) reduction in aquatic sediments. NTA solubilized Fe(III) from the aquifer sediments. NTA stimulation of microbial Fe(III) reduction did not appear to be the result of making calcium, magnesium, potassium, or trace metals more available to the microorganisms. Stimulation of Fe(III) reduction could not be attributed to NTA serving as a source of carbon or fixed nitrogen for Fe(III)-reducing bacteria as NTA was not degraded in the sediments. Studies with the Fe(III)-reducing microorganism, Geobacter metallireducens, and pure Fe(III)-oxide forms, demonstrated that NTA stimulated the reduction of a variety of Fe(III) forms, including highly crystalline Fe(III)-oxides such as goethite and hematite. The results suggest that NTA solubilization of insoluble Fe(III)-oxide is an important mechanism for the stimulation of Fe(III) reduction by NTA in aquifer sediments.

  2. Slide fastener reduction of graphene-oxide edges by calcium: insight from ab initio molecular dynamics.

    Science.gov (United States)

    Xie, Sheng-Yi; Li, Xian-Bin; Tian, Wei Quan; Wang, Dan; Chen, Nian-Ke; Han, Dong; Sun, Hong-Bo

    2014-09-15

    The reduction of graphene oxide can be used as a simple way to produce graphene on a large scale. However, the numerous edges produced by the oxidation of graphite seriously degrade the quality of the graphene and its carrier transport property. In this work, the reduction of oxygen-passivated graphene edges and the subsequent linking of separated graphene sheets by calcium are investigated by using first-principles calculations. The calculations show that calcium can effectively remove the oxygen groups from two adjacent edges. The joining point of the edges serves as the starting point of the reduction and facilitates the reaction. Once the oxygen groups are removed, the crack is sutured. If the joining point is lacking, it becomes difficult to zip the separated fragments. A general electron-reduction model and a random atom-reduction model are suggested for these two situations. The present study sheds light on the reduction of graphene-oxide edges by using reactive metals to give large-sized graphene through a simple chemical reaction.

  3. Reduction of Mn-oxides by ferrous iron in a flow system: column experiment and reactive transport modeling

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Appelo, C. A. J.

    2000-01-01

    The reduction of Mn-oxide by Fe21 was studied in column experiments, using a column filled with natural Mn-oxide coated sand. Analysis of the Mn-oxide indicated the presence of both Mn(III) and Mn(IV) in the Mn-oxide. The initial exchange capacity of the column was determined by displacement of a...

  4. Wettability modification of graphene oxide thin film through the photocatalytic reduction

    Directory of Open Access Journals (Sweden)

    2016-06-01

    Full Text Available In this paper, the effect of photocatalytic reduction on hydrophilicity of graphene oxide nanosheets is presented. The graphene oxide nanosheets were prepared by oxidation and exfoliation of natural graphite. The prepared samples were exposed to UV irradiation in presence of TiO2 nanoparticles. Raman spectroscopy and atomic force microscopy show that roughness of the surface is increased due to increasing irradiation. Also, the hydrophilicity of samples by measuring the contact angle of micro-liter droplets of deionized water, showed that by increasing exposure time up to 8 hours the contact angle of samples in crease from about 27 degrees to about 89 degrees.

  5. Pyrite oxidation and reduction - Molecular orbital theory considerations. [for geochemical redox processes

    Science.gov (United States)

    Luther, George W., III

    1987-01-01

    In this paper, molecular orbital theory is used to explain a heterogeneous reaction mechanism for both pyrite oxidation and reduction. The mechanism demonstrates that the oxidation of FeS2 by Fe(3+) may occur as a result of three important criteria: (1) the presence of a suitable oxidant having a vacant orbital (in case of liquid phase) or site (solid phase) to bind to the FeS2 via sulfur; (2) the initial formation of a persulfido (disulfide) bridge between FeS2 and the oxidant, and (3) an electron transfer from a pi(asterisk) orbital in S2(2-) to a pi or pi(asterisk) orbital of the oxidant.

  6. Pulsed laser irradiation for environment friendly reduction of graphene oxide suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Ghadim, Ehsan Ezzatpour [Young Researchers and Elite Club, Central Tehran Branch, Islamic Azad University, Tehran 13185-768 (Iran, Islamic Republic of); Rashidi, Nasim; Kimiagar, Salimeh [Department of Physic, Azad University, Central Tehran Branch (IAUCTB), Tehran 14676-6831 (Iran, Islamic Republic of); Akhavan, Omid, E-mail: oakhavan@sharif.edu [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of); Manouchehri, Firouzeh [Department of Chemistry, Azad University, Central Tehran Branch (IAUCTB), Tehran 14676-6831 (Iran, Islamic Republic of); Ghaderi, Elham [Nanobiotechnology Research Lab., Division of Advanced Materials, Azadi Ave., Tehran (Iran, Islamic Republic of)

    2014-05-01

    Highlights: • Application of pulsed laser irradiation for environment-friendly reduction of graphene oxide sheets. • Reduction of graphene oxide suspension in an ammonia solution by laser irradiation without any significant aggregation of the reduced sheets. • The reduction level obtained through the laser irradiation is comparable with the reduction level obtainable by hydrazine. - Abstract: Graphene oxide (GO) sheets were synthesized through a modified Hummers’ method. Using high resolution transmission electron microscopy the thickness of the GO sheets in a multilayer structure of stacked GO sheets was found ∼0.8 nm. A nanosecond pulsed laser (with wavelength of 532 nm and average power of 0.3 W) was applied for effective and environment friendly reduction of the GO sheets in an ammonia solution (pH ∼9) at room temperature conditions. The deoxygenation of the GO sheets by the pulsed laser reduction method was confirmed by using UV–visible, Fourier transform infrared, X-ray photoelectron spectroscopy (XPS) and thermo gravimetric analysis. Based on XPS analysis, the O/C ratio of the GO sheets decreased from 49% to 21% after 10 min laser irradiation. This reduction efficiency was comparable with the efficiency achieved by hydrazine which yielded the O/C ratio of 15% at 80 °C after 10 min. Using Raman spectroscopy it was found that the pulsed laser reduction method resulted in nearly no aggregation of the reduced GO sheets in the ammonia solution. These results can help to further promotion and application of pulsed lasers in environment friendly reduction of GO.

  7. Direct Reduction of High-phosphorus Oolitic Hematite Ore Based on Biomass Pyrolysis

    Institute of Scientific and Technical Information of China (English)

    Dong-bo HUANG; Yan-bing ZONG; Ru-fei WEI; Wei GAO; Xiao-ming LIU

    2016-01-01

    Direct reduction of high-phosphorus oolitic hematite ore based on biomass pyrolysis gases (CO,H2 ,and CH4 ),tar,and char was conducted to investigate the effects of reduction temperature,iron ore-biomass mass ratio, and reduction time on the metallization rate.In addition,the effect of particle size on the dephosphorization and iron recovery rate was studied by magnetic separation.It was determined that the metallization rate of the hematite ore could reach 99.35% at iron ore-biomass mass ratio of 1∶0.6,reduction temperature of 1 100 ℃,and reduction time of 5 5 min.The metallization rate and the aggregation degree of iron particles increase with the increase of reduction temperature.The particle size of direct reduced iron (DRI)has a great influence on the quality of the iron concentrate during magnetic separation.The separation degree of slag and iron was improved by the addition of 1 5 mass% sodi-um carbonate.DRI with iron grade of 89.11%,iron recovery rate of 83.47%,and phosphorus content of 0.28% can be obtained when ore fines with particle size of -10μm account for 78.15%.

  8. Spinel Metal Oxide-Alkali Carbonate-Based, Low-Temperature Thermochemical Cycles for Water Splitting and CO_2 Reduction

    OpenAIRE

    Xu, Bingjun; Bhawe, Yashodhan; Davis, Mark E.

    2013-01-01

    A manganese oxide-based, thermochemical cycle for water splitting below 1000 °C has recently been reported. The cycle involves the shuttling of Na+ into and out of manganese oxides via the consumption and formation of sodium carbonate, respectively. Here, we explore the combinations of three spinel metal oxides and three alkali carbonates in thermochemical cycles for water splitting and CO_2 reduction. Hydrogen evolution and CO_2 reduction reactions of metal oxides with a given alkali carbona...

  9. Relationship Between Iron Whisker Growth and Doping Amount of Oxide During Fe2O3 Reduction

    Science.gov (United States)

    Gong, Xuzhong; Zhao, Zhilong; Wang, Zhi; Zhang, Ben; Guo, Lei; Guo, Zhancheng

    2016-04-01

    Iron whisker growth during Fe2O3 doped with oxide reduced by CO was investigated by using in situ observation and scanning electron microscopy. The results indicated that the minimum doping amount (MDA) of various oxides, hindering the iron whisker growth, was different. The MDA of Al2O3, Li2O, Na2O, and K2O was 0.5, 0.4, 4, and 12 pct, respectively. From the reduction rate, it was found that Li2O, MgO, and Al2O3 had some suppressive effects on the Fe2O3 reduction process, thus, confining the growth of iron whisker. However, other oxides had some catalytic effects on the Fe2O3 reduction process (Fe2O3-Fe3O4-FeO-Fe), such as CaO, SrO, BaO, Na2O, and K2O. As long as their doping amount was enough, these oxides could inhibit the diffusion of the Fe atom. When the metal ionic radius in doped oxide was bigger than that of Fe3+, such as Ca2+, Sr2+, Ba2+, Na+, and K+, there were lots of spaces left in Fe2O3 doped with oxide after reduction, improving Fe atom diffusion. Consequently, their MDA was more than that of small radius to restrain the growth of iron whisker. Finally, the relationship between corresponding metal ionic radius, electron layer number, valence electron number, and MDA of oxide was expressed by using data fitting as follows: N_{{{{A}}y {{O}}x }} = 1.3 × 10^{ - 5} × {r_{{{{A}}^{x + } }}2 × √{n_{{{{A}}^{x + } }} } }/{f_{q }}

  10. Synthesis of reduced graphene oxide (rGO) via chemical reduction

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Alpana, E-mail: alpanarangoli@gmail.com; Rangra, V. S. [Department of Physics, Himachal Pradesh University, Shimla (India); Kumar, Sunil [Department of Applied Sciences, Sri Sai University, Palampur (India)

    2015-05-15

    Natural flake Graphite was used as the starting material for the graphene synthesis. In the first step flake graphite was treated with oxidizing agents under vigorous conditions to obtain graphite oxide. Layered graphite oxide decorated with oxygen has large inter-layer distance leading easy exfoliation into single sheets by ultrasonication giving graphene oxide. In the last step exfoliated graphene oxide sheets were reduced slowly with the help of reducing agent to obtain fine powder which is labeled as reduced graphene oxide (rGO). This rGO was further characterized by X-Ray Diffraction (XRD), Scanning Tunneling Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy techniques. XRD pattern shows peaks corresponding to (002) graphitic lattice planes indicating the formation of network of sp{sup 2} like carbon structure. SEM images show the ultrathin, wrinkled, paper-like morphology of graphene sheets. IR study shows that the graphite has been oxidized to graphite oxide with the presence of various absorption bands confirming the presence of oxidizing groups. The FTIR spectrum of rGO shows no sharp peaks confirming the efficient reduction of rGO. The Raman spectrum shows disorder in the graphene sheets.

  11. Smelting in cupola furnace for re carburization of direct reduction iron (DRI)

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez, J. L.; Tremps, E.; Ruiz-Bustinza, I.; Moron, C.; GarciaGarcia, A.; Robla, J. I.; Gonzalez-Gasca, C.

    2015-07-01

    Herein the synthesis of iron-carbon saturated alloys (foundries) melting in cupola furnaces from direct reduction iron is described. The fundamentals are reviewed and combinations undertaken are discussed along with their results, including conclusions and recommendations for follow up. (Author)

  12. Directed vapor deposition of lithium manganese oxide films

    Science.gov (United States)

    Jin, Sang-Wan

    Electron beam evaporation and sputtering techniques are used to fabricate multilayered thin film structures. However, these techniques suffer several drawbacks resulting from (i) the complex chemistries of the lithiated oxide layers used for the cathode and electrolyte, (ii) the need for precise microstructure control in systems with many metastable phases, and (iii) the low deposition rate and poor material utilization efficiency, which slows the application of this energy storage approach. This dissertation has investigated the use of a novel electron-beam directed vapor deposition (EB-DVD) method for the synthesis of thin film batteries. The dissertation focuses upon the cathode layer of a representative Li-ion thin film battery system and investigates in detail the deposition of lithium manganese oxide films. Many phases with offering various electrochemical performance exist in the Li-Mn-O system and the thesis also investigates the use of processing conditions to control the structure and composition of these cathode layers. In the EB-DVD approach, a high voltage electron beam is used to evaporate a source material in the throat of a nozzle that forms a coaxial transonic gas jet around the vapor. The gas jet entrains and transports the vapor to a substrate where the deposition occurs. Directed simulation of Monte Carlo (DSMC) methods indicated that the vapor plume could be matched to a substrate diameter, and the deposition rate (and vapor utilization efficiency) therefore controlled by adjusting the pressure ratio up and downstream of the nozzle opening in the deposition chamber, and by varying the gas jet density and speed. The highest deposition rates were obtained with a high pressure ratio and the gas jet density. These observations are found to be consistent with the experimental results. Deposition rates up to 16 nm/s could be achieved using the most effective gas entrainment conditions identified by DSMC calculation. This was about a factor of ten

  13. Controllable reduction of graphene oxide and its application during the fabrication of high dielectric constant composites

    Science.gov (United States)

    Liu, Hui; Xu, Peng; Yao, Haibo; Chen, Wenhui; Zhao, Jianying; Kang, Chuanqing; Bian, Zheng; Gao, Lianxun; Guo, Haiquan

    2017-10-01

    The synthesis of reduced graphene oxide (RGO) with various reduction extents was carried out in organic solvent using 1,4-diiodobutane as the reducing agent at moderate temperatures. Results showed that the C/O ratio of RGO nanosheet surface could be tailored by adjusting the ratio of graphene oxide (GO) and reducing agent. The controllable reduction strategy was applied to the fabrication of high dielectric constant graphene/polyimide composites via the in situ reduction of GO. The reduction extents of RGO in polymer matrix can be readily manipulated just through altering the addition of the reducing agent. The dielectric constants of gaphene/polyimide composites were significantly enhanced with the increasing of the reduction extent of RGO. Moreover, the mechanical properties of the composites were also affected by the reduction extent of RGO due to the decreases of the oxygen functional groups of RGO surface. Hence, the in situ controllable reduction of GO should be quite an ideal method for the fabrication of high dielectric constant composites with the tunable combination properties.

  14. ANAEROBIC DDT BIOTRANSFORMATION: ENHANCEMENT BY APPLICATION OF SURFACTANTS AND LOW OXIDATION REDUCTION POTENTIAL

    Science.gov (United States)

    Enhancement of anaerobic DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane) biotransformation by mixed cultures was studied with application of surfactants and oxidation reduction potential reducing agents. Without amendments, DDT transformation resulted mainly in the pr...

  15. Primary oxidation and reduction products in x-irradiated aspartic acid

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S.M.; Budzinski, E.E.; Box, H.C.

    1976-08-01

    The primary reduction products identified by ESR--ENDOR spectroscopy in single crystals of DL-aspartic acid hydrochloride irradiated at 4.2degreeK are anions formed by addition of an electron to the carbonyl oxygen atoms of the carboxylic acid groups. The main consequence of the oxidation process is to produce a hole centered mainly on atomic chlorine. (AIP)

  16. A consistent reaction scheme for the selective catalytic reduction of nitrogen oxides with ammonia

    DEFF Research Database (Denmark)

    Janssens, Ton V.W.; Falsig, Hanne; Lundegaard, Lars Fahl;

    2015-01-01

    are required in the reduction, and, nally, oxidation by NO + O2 or NO2 leads to the same state of the catalyst. These points are shown experimentally for a Cu-CHA catalyst, by combining in situ X-ray absorption spectrosocpy (XAS), electron paramagnetic resonance (EPR), and Fourier transform infrared...

  17. Direct patterning of gold oxide thin films by focused ion-beam irradiation

    Science.gov (United States)

    Machalett, F.; Edinger, K.; Melngailis, J.; Diegel, M.; Steenbeck, K.; Steinbeiss, E.

    For direct writing of electrically conducting connections and areas into insulating gold oxide thin films a scanning Ar+ laser beam and a 30 keV Ga+ focused ion beam (FIB) have been used. The gold oxide films are prepared by magnetron sputtering under argon/oxygen plasma. The patterning of larger areas (dimension 10-100 μm) has been carried out with the laser beam by local heating of the selected area above the decomposition temperature of AuOx (130-150 °C). For smaller dimensions (100 nm to 10 μm) the FIB irradiation could be used. With both complementary methods a reduction of the sheet resistance by 6-7 orders of magnitude has been achieved in the irradiated regions (e.g. with FIB irradiation from 1.5×107 Ω/□ to approximately 6 Ω/□). The energy-dispersive X-ray analysis (EDX) show a considerably reduced oxygen content in the irradiated areas, and scanning electron microscopy (SEM), as well as atomic force microscopy (AFM) investigations, indicate that the FIB patterning in the low-dose region (1014 Ga+/cm2) is combined with a volume reduction, which is caused by oxygen escape rather than by sputtering.

  18. Linear sweep voltametry studies on oxygen reduction of some oxides in alkaline electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ananth, M.V. [Ni-MH Section, Electrochemical Power Sources Division, Central Electrochemical Research Institute, Karaikudi, 630 006 Tamil Nadu (India); Giridhar, V.V. [Electrodics and Electrocatalysis (EEC) Division, Central Electrochemical Research Institute, Karaikudi, 630 006 Tamil Nadu (India); Renuga, K. [Department of Chemistry, Thiagarajar College, Madurai 625 009 (India)

    2009-01-15

    The study uses linear sweep voltametry (LSV) to observe the efficiency of oxygen reduction on some oxides and their mixtures in 6 M KOH at 25 C. The investigated materials are Ag{sub 2}O, MnO{sub 2}, Sm{sub 2}O{sub 3}, Dy{sub 2}O{sub 3} and NdO{sub 2}. The electrocatalytic oxygen reduction reactions (ORR) on Teflon-bonded, oxide + graphite electrodes are studied. The oxygen reduction potentials for electrodes containing these materials as catalyst are seen as -60.67, -270.31, -111, -159.58 and -130.24 mV, respectively. Mixture combinations of these oxides give a higher ORR peak current thereby showing evidence of synergetic effect. Air-MH cells using some of the above investigated oxides as catalyst for air electrode are constructed and studied. Best performance is obtained with silver oxide. The LSV findings are in accordance with air-MH cell charge/discharge experiments and for best performance prefer shift of the ORR onset potential to more positive positions. (author)

  19. Direct reduction of carburized pre-reduced pellets by microwave heating

    Institute of Scientific and Technical Information of China (English)

    胡兵; 黄柱成; 易凌云; 姜涛

    2014-01-01

    A new iron-making process using carburized pre-reduced iron ore pellets and microwave heating is investigated. The pre-reduced pellets, with a porous structure, and fine particles are carburized homogeneously at 400-650 °C in a CO atmosphere. The carburized carbon not only acts reaction as a reduction agent, but also absorbs microwave in the reduction process. Hence, the carburized pre-reduced pellets can be rapidly reduced by microwave heating. There are three procedures involved in the process, namely, gas-based pre-reduction, low-temperature carburization and deep reduction by microwave heating. Carburized pre-reduced iron ore pellets show a rapid temperature rise that is twice as fast as the results for pre-reduced pellets in the laboratory. This not only improves the efficiency of the microwave heating, but also accelerates the reduction of iron oxides. The temperature of the pre-reduced pellets rises to 1050 °C in 45 min when the carburization rate is 2.02%, and the metallization rate and compressive strength reach 94.24%and 1725 N/pellet, respectively.

  20. Laser-Induced Reductive Sintering of Nickel Oxide Nanoparticles under Ambient Conditions

    KAUST Repository

    Paeng, Dongwoo

    2015-03-19

    © 2015 American Chemical Society. This work is concerned with the kinetics of laser-induced reductive sintering of nonstoichiometric crystalline nickel oxide (NiO) nanoparticles (NPs) under ambient conditions. The mechanism of photophysical reductive sintering upon irradiation using a 514.5 nm continuous-wave (CW) laser on NiO NP thin films has been studied through modulating the laser power density and illumination time. Protons produced due to high-temperature decomposition of the solvent present in the NiO NP ink, oxygen vacancies in the NiO NPs, and electronic excitation in the NiO NPs by laser irradiation all affect the early stage of the reductive sintering process. Once NiO NPs are reduced by laser irradiation to Ni, they begin to coalesce, forming a conducting material. In situ optical and electrical measurements during the reductive sintering process take advantage of the distinct differences between the oxide and the metallic phases to monitor the transient evolution of the process. We observe four regimes: oxidation, reduction, sintering, and reoxidation. A characteristic time scale is assigned to each regime.

  1. Advanced experimental analysis of controls on microbial Fe(III) oxide reduction. First year progress report

    Energy Technology Data Exchange (ETDEWEB)

    Roden, E.E.; Urrutia, M.M.

    1997-07-01

    'The authors have made considerable progress toward a number of project objectives during the first several months of activity on the project. An exhaustive analysis was made of the growth rate and biomass yield (both derived from measurements of cell protein production) of two representative strains of Fe(III)-reducing bacteria (Shewanellaalga strain BrY and Geobactermetallireducens) growing with different forms of Fe(III) as an electron acceptor. These two fundamentally different types of Fe(III)-reducing bacteria (FeRB) showed comparable rates of Fe(III) reduction, cell growth, and biomass yield during reduction of soluble Fe(III)-citrate and solid-phase amorphous hydrous ferric oxide (HFO). Intrinsic growth rates of the two FeRB were strongly influenced by whether a soluble or a solid-phase source of Fe(III) was provided: growth rates on soluble Fe(III) were 10--20 times higher than those on solid-phase Fe(III) oxide. Intrinsic FeRB growth rates were comparable during reduction of HF0 and a synthetic crystalline Fe(III) oxide (goethite). A distinct lag phase for protein production was observed during the first several days of incubation in solid-phase Fe(III) oxide medium, even though Fe(III) reduction proceeded without any lag. No such lag between protein production and Fe(III) reduction was observed during growth with soluble Fe(III). This result suggested that protein synthesis coupled to solid-phase Fe(III) oxide reduction in batch culture requires an initial investment of energy (generated by Fe(III) reduction), which is probably needed for synthesis of materials (e.g. extracellular polysaccharides) required for attachment of the cells to oxide surfaces. This phenomenon may have important implications for modeling the growth of FeRB in subsurface sedimentary environments, where attachment and continued adhesion to solid-phase materials will be required for maintenance of Fe(III) reduction activity. Despite considerable differences in the rate and

  2. Recovery of alumina and ferric oxide from Bayer red mud rich in iron by reduction sintering

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-bin; XIAO Wei; LIU Wei; LIU Gui-hua; PENG Zhi-hong; ZHOU Qiu-sheng; QI Tian-gui

    2009-01-01

    A great amount of red mud generated from alumina production by Bayer process not only threatens the environment but also causes waste of secondary resources. High-iron-content red mud from Bayer process was employed to recover alumina and ferric oxide by the process of reduction-sintering, leaching and then magnetic beneficiation. Results of thermodynamic analyses show that ferric oxide should be reduced to Fe if reduction of ferric oxide and formation of sodium aluminate and calcium silicate happen simultaneously. Experimental results indicate that alumina recovery of Bayer red mud can reach 89.71%, and Fe recovery rate and the grade of magnetite concentrate are 60.67% and 61.78%, respectively, under the optimized sintering conditions.

  3. Plasma in-liquid method for reduction of zinc oxide in zinc nanoparticle synthesis

    Science.gov (United States)

    Amaliyah, Novriany; Mukasa, Shinobu; Nomura, Shinfuku; Toyota, Hiromichi; Kitamae, Tomohide

    2015-02-01

    Metal air-batteries with high-energy density are expected to be increasingly applied in electric vehicles. This will require a method of recycling air batteries, and reduction of metal oxide by generating plasma in liquid has been proposed as a possible method. Microwave-induced plasma is generated in ethanol as a reducing agent in which zinc oxide is dispersed. Analysis by energy-dispersive x-ray spectrometry (EDS) and x-ray diffraction (XRD) reveals the reduction of zinc oxide. According to images by transmission electron microscopy (TEM), cubic and hexagonal metallic zinc particles are formed in sizes of 30 to 200 nm. Additionally, spherical fiber flocculates approximately 180 nm in diameter are present.

  4. Reduction Kinetics of Electric Arc Furnace Oxidizing Slag by Al-Fe Alloy

    Science.gov (United States)

    Lee, Jaehong; Oh, Joon Seok; Lee, Joonho

    2016-09-01

    Effects of temperature and slag basicity on the reduction rate of iron oxide in molten synthetic electric arc furnace oxidizing slag by Al-40 wt.%Fe alloy was investigated. An alloy sample was dropped into molten slag in an MgO crucible. When the initial slag temperature was 1723 K, there was no reduction. However, when the initial slag temperature was 1773 K and the slag basicity was 1.1, the reduction was initiated and the temperature of the slag rapidly increased. When the slag basicity was 1.1, increasing the initial slag temperature from 1773 K to 1823 K increases the reaction rate. As the slag basicity increased from 1.1 to 1.4 at 1773 K, the reaction rate increased. From SEM analysis, it was found that an Al2O3 or a spinel phase at the slag-metal interface inhibited the reaction at a lower temperature and a lower slag basicity.

  5. Descriptors and Thermodynamic Limitations of Electrocatalytic Carbon Dioxide Reduction on Rutile Oxide Surfaces

    DEFF Research Database (Denmark)

    Bhowmik, Arghya; Vegge, Tejs; Hansen, Heine Anton

    2016-01-01

    and it defines the left leg of the activity volcano for CO2RR. HCOOH* is a key intermediate for products formed through further reduction, for example, methanediol, methanol, and methane. The surfaces that do not bind HCOOH* are selective towards formic acid (HCOOH) production, but hydrogen evolution limits......A detailed understanding of the electrochemical reduction of CO2 into liquid fuels on rutile metal oxide surfaces is developed by using DFT calculations. We consider oxide overlayer structures on RuO2(1 1 0) surfaces as model catalysts to elucidate the trends and limitations in the CO2 reduction...... reaction (CO2RR) based on thermodynamic analysis. We aim to specify the requirements for CO2RR catalysts to establish adsorbate scaling relations and use these to derive activity volcanoes. Computational results show that the OH* binding free energy is a good descriptor of the thermodynamic limitations...

  6. Redox Sensitivities of Global Cellular Cysteine Residues under Reductive and Oxidative Stress.

    Science.gov (United States)

    Araki, Kazutaka; Kusano, Hidewo; Sasaki, Naoyuki; Tanaka, Riko; Hatta, Tomohisa; Fukui, Kazuhiko; Natsume, Tohru

    2016-08-01

    The protein cysteine residue is one of the amino acids most susceptible to oxidative modifications, frequently caused by oxidative stress. Several applications have enabled cysteine-targeted proteomics analysis with simultaneous detection and quantitation. In this study, we employed a quantitative approach using a set of iodoacetyl-based cysteine reactive isobaric tags (iodoTMT) and evaluated the transient cellular oxidation ratio of free and reversibly modified cysteine thiols under DTT and hydrogen peroxide (H2O2) treatments. DTT treatment (1 mM for 5 min) reduced most cysteine thiols, irrespective of their cellular localizations. It also caused some unique oxidative shifts, including for peroxiredoxin 2 (PRDX2), uroporphyrinogen decarboxylase (UROD), and thioredoxin (TXN), proteins reportedly affected by cellular reactive oxygen species production. Modest H2O2 treatment (50 μM for 5 min) did not cause global oxidations but instead had apparently reductive effects. Moreover, with H2O2, significant oxidative shifts were observed only in redox active proteins, like PRDX2, peroxiredoxin 1 (PRDX1), TXN, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Overall, our quantitative data illustrated both H2O2- and reduction-mediated cellular responses, whereby while redox homeostasis is maintained, highly reactive thiols can potentiate the specific, rapid cellular signaling to counteract acute redox stress.

  7. Direct and quinone-mediated palladium reduction by Geobacter sulfurreducens: mechanisms and modeling.

    Science.gov (United States)

    Pat-Espadas, Aurora M; Razo-Flores, Elías; Rangel-Mendez, J Rene; Cervantes, Francisco J

    2014-01-01

    Palladium(II) reduction to Pd(0) nanoparticles by Geobacter sulfurreducens was explored under conditions of neutral pH, 30 °C and concentrations of 25, 50, and 100 mg of Pd(II)/L aiming to investigate the effect of solid species of palladium on their microbial reduction. The influence of anthraquinone-2,6-disulfonate was reported to enhance the palladium reaction rate in an average of 1.7-fold and its addition is determining to achieve the reduction of solid species of palladium. Based on the obtained results two mechanisms are proposed: (1) direct, which is fully described considering interactions of amide, sulfur, and phosphoryl groups associated to proteins from bacteria on palladium reduction reaction, and (2) quinone-mediated, which implies multiheme c-type cytochromes participation. Speciation analysis and kinetic results were considered and integrated into a model to fit the experimental data that explain both mechanisms. This work provides elements for a better understanding of direct and quinone-mediated palladium reduction by G. sulfurreducens, which could facilitate metal recovery with concomitant formation of valuable palladium nanoparticles in industrial processes.

  8. Reduction of aqueous transition metal species on the surfaces of Fe(II)-containing oxides

    Science.gov (United States)

    White, A.F.; Peterson, M.L.

    1996-01-01

    Experimental studies demonstrate that structural Fe(II) in magnetite and ilmenite heterogeneously reduce aqueous ferric, cupric, vanadate, and chromate ions at the oxide surfaces over a pH range of 1-7 at 25??C. For an aqueous transition metal m, such reactions are 3[Fe2+Fe3+2]O4(magnetite) + 2/nmz ??? 4[Fe3+2]O3(maghemite) + Fe2+ + 2/nmz-n and 3[Fe2+Ti]O3(ilmenite) + 2/nmz ??? Fe3+2Ti3O9(pseudorutile) + Fe2+ + 2/nmz-n, where z is the valance state and n is the charge transfer number. The half cell potential range for solid state oxidation [Fe(II)] ??? [Fe(III)] is -0.34 to -0.65 V, making structural Fe(II) a stronger reducing agent than aqueous Fe2+ (-0.77 V). Reduction rates for aqueous metal species are linear with time (up to 36 h), decrease with pH, and have rate constants between 0.1 and 3.3 ?? 10-10 mol m-2 s-1. Iron is released to solution both from the above reactions and from dissolution of the oxide surface. In the presence of chromate, Fe2+ is oxidized homogeneously in solution to Fe3+. X-ray photoelectron spectroscopy (XPS) denotes a Fe(III) oxide surface containing reduced Cr(III) and V(IV) species. Magnetite and ilmenite electrode potentials are insensitive to increases in divalent transition metals including Zn(II), Co(II), Mn(II), and Ni(II) and reduced V(IV) and Cr(III) but exhibit a log-linear concentration-potential response to Fe(III) and Cu(II). Complex positive electrode responses occur with increasing Cr(VI) and V(V) concentrations. Potential dynamic scans indicate that the high oxidation potential of dichromate is capable of suppressing the cathodic reductive dissolution of magnetite. Oxide electrode potentials are determined by the Fe(II)/Fe(III) composition of the oxide surface and respond to aqueous ion potentials which accelerate this oxidation process. Natural magnetite sands weathered under anoxic conditions are electrochemically reactive as demonstrated by rapid chromate reduction and the release of aqueous Fe(III) to experimental

  9. Selective catalytic reduction of nitric oxide by methane over cerium and silver ion-exchanged ZSM-5 zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhijiang; Flytzani-Stephanopoulos, Maria [Department of Chemical Engineering, Tufts University, Medford, MA (United States)

    1997-12-31

    A new catalyst comprising cerium and silver ion-exchanged ZSM-5 zeolite is reported in this paper, for the reduction of nitric oxide by methane in the presence of excess oxygen. The bi-cation exchanged Ce-Ag-ZSM-5 catalyst was very active for this reaction, while either Ce-ZSM-5 or Ag-ZSM-5 alone showed low activity. The presence of oxygen in the feed gas mixture enhanced the activity of the catalyst and the NO conversion to N{sub 2} increased with the CH{sub 4}/NO ratio and Ag loading of the zeolite. The presence of water vapor had a small adverse effect on the catalyst activity. The coexistence of Ce and Ag ions in the zeolite is crucial for achieving high NO conversion to N{sub 2}. A small amount of cerium is adequate to promote the selective catalytic reduction of NO. The two main functions of Ce ions are (1) to provide the Ag ion sites with NO{sub 2} by catalyzing the oxidation of NO to NO{sub 2} and (2) to suppress the direct CH{sub 4} oxidation to CO{sub 2}. The Ag sites are the active centers where the reaction of NO{sub 2} with CH{sub 4} takes place

  10. Decision-directed iterative methods for PAPR reduction in optical wireless OFDM systems

    Science.gov (United States)

    Azim, Ali W.; Le Guennec, Yannis; Maury, Ghislaine

    2017-04-01

    In this paper, we propose two iterative decision-directed methods for peak-to-average power ratio (PAPR) reduction in optical-orthogonal frequency division multiplexing (O-OFDM) systems. The proposed methods are applicable to state-of-the-art intensity modulation-direct detection (IM-DD) O-OFDM techniques for optical wireless communication (OWC) systems, including both direct-current (DC) biased O-OFDM (DCO-OFDM), and asymmetrically clipped O-OFDM (ACO-OFDM). Conventional O-OFDM suffers from high power consumption due to high PAPR. The high PAPR of the O-OFDM signal can be counteracted by clipping the signal to a predefined threshold. However, because of clipping an inevitable distortion occurs due to the loss of useful information, thus, clipping mitigation methods are required. The proposed iterative decision-directed methods operate at the receiver, and recover the lost information by mitigating the clipping distortion. Simulation results acknowledge that the high PAPR of O-OFDM can be significantly reduced using clipping, and the proposed methods can successfully circumvent the clipping distortions. Furthermore, the proposed PAPR reduction methods exhibit a much lower computational complexity compared to standard PAPR reduction methods.

  11. Effects of reduction time on the structural, electrical and thermal properties of synthesized reduced graphene oxide nanosheets

    Indian Academy of Sciences (India)

    Mohamad Fahrul Radzi Hanifah; Juhana Jaafar; Madzlan Aziz; A F Ismail; M H D Othman; Mukhlis A Rahman

    2015-10-01

    The reduction of graphene oxide (GO) nanosheet is a promising route to produce a stable colloidal dispersion of reduced graphene oxide (RGO) nanosheets in a large scale. The production of RGO nanosheet is one of the important topics in nanotechnology disciplines due to its contribution in various applications, such as the platinum catalyst support in direct methanol fuel cell. Therefore, in this paper, the RGO nanosheets were prepared via highly efficient chemical reduction reaction of exfoliated GO nanosheets using sodium oxalate (Na2C2O4) as the reducing agent. Extensive characterizations have been conducted in terms of structural, thermal stability and electrical conductivity properties by means of high-resolution transmission microscopy, the Fourier transform infrared spectroscopy, UV–visible spectroscopy, 13C NMR and four-point probe conductivity measurement. The results indicate that most of oxygen-containing functional groups from GO nanosheets have been removed and the RGO-3 possess greater thermal stability compared to GO nanosheets. The prepared RGO-3 shows the highest electrical conductivity at room temperature which is ∼ 2.0 × 103 S m−1. Based on these analyses, the plausible mechanism of reduction of GO to RGO by sodium oxalate is well proposed.

  12. A direct electrochemical route from oxides to TiMn2 hydrogen storage alloy☆

    Institute of Scientific and Technical Information of China (English)

    Jing Zhu; Lei Dai; Yao Yu; Jilin Cao; Ling Wang

    2015-01-01

    This study is for investigating the direct electro-deoxidation of mixed TiO2–MnO2 powder to prepare TiMn2 al oy in molten calcium chloride. The influences of process parameters, such as sintering temperature, cell voltage, and electrolysis time, on the electrolysis process were examined to investigate the mechanism of al oy formation. The composition and morphology of the products were analyzed by XRD and SEM, respectively. The electrochemical property of TiMn2 al oy was investigated by cyclic voltammetry measurements. The results show that pure TiMn2 can be prepared by direct electrochemical reduction of mixed TiO2/MnO2 pellets at a voltage of 3.1 V in molten calcium chloride of 900 °C for 7 h. The electro-deoxidation proceeds from the reduction of manganese oxides to Mn, which is reduced by TiO2 or CaTiO3 to form TiMn2 al oy. The cyclic voltammetry measurements using pow-der microelectrode show that the prepared TiMn2 al oy has good electrochemical hydrogen storage property. © 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. Al rights reserved.

  13. The reduction potential of nitric oxide (NO) and its importance to NO biochemistry.

    Science.gov (United States)

    Bartberger, Michael D; Liu, Wei; Ford, Eleonora; Miranda, Katrina M; Switzer, Christopher; Fukuto, Jon M; Farmer, Patrick J; Wink, David A; Houk, Kendall N

    2002-08-20

    A potential of about -0.8 (+/-0.2) V (at 1 M versus normal hydrogen electrode) for the reduction of nitric oxide (NO) to its one-electron reduced species, nitroxyl anion (3NO-) has been determined by a combination of quantum mechanical calculations, cyclic voltammetry measurements, and chemical reduction experiments. This value is in accord with some, but not the most commonly accepted, previous electrochemical measurements involving NO. Reduction of NO to 1NO- is highly unfavorable, with a predicted reduction potential of about -1.7 (+/-0.2) V at 1 M versus normal hydrogen electrode. These results represent a substantial revision of the derived and widely cited values of +0.39 V and -0.35 V for the NO/3NO- and NO/1NO- couples, respectively, and provide support for previous measurements obtained by electrochemical and photoelectrochemical means. With such highly negative reduction potentials, NO is inert to reduction compared with physiological events that reduce molecular oxygen to superoxide. From these reduction potentials, the pKa of 3NO- has been reevaluated as 11.6 (+/-3.4). Thus, nitroxyl exists almost exclusively in its protonated form, HNO, under physiological conditions. The singlet state of nitroxyl anion, 1NO-, is physiologically inaccessible. The significance of these potentials to physiological and pathophysiological processes involving NO and O2 under reductive conditions is discussed.

  14. Observations of Oxygen Ion Behavior in the Lithium- Based Electrolytic Reduction of Uranium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, S.D.; Li, S.X.; Serrano-Rodriguez, B.E. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States)

    2009-06-15

    Development of a lithium-based electrolytic reduction process to convert oxide fuel to metal is being pursued by various researchers to facilitate subsequent pyro-processing of the metalized fuel product. In such pursuits, uranium oxide particles are contacted by an electrically conductive material and immersed in a pool of LiCl-Li{sub 2}O at 650 deg. C. A controlled current is passed between the fuel particles (as the cathode) and a suitable anode to reduce the uranium oxide to metal at the cathode and to oxidize oxygen ions to gas at the anode. In this process, the effective liberation and transport of oxygen ions from the oxide fuel particles within a cathode structure to the anode is paramount to the viability of this process. Parametric studies were performed on a lithium-based electrolytic reduction process at bench-scale in an inert atmosphere glovebox to investigate the behavior of oxygen ions in the reduction of uranium oxide for various electrochemical cell configurations. Specifically, a series of eight electrolytic reduction runs in a common salt bath of LiCl - 1 wt% Li{sub 2}O was performed with varying applied charges (75 - 150% of theoretical) and fuel basket containment materials (stainless steel wire mesh and sintered stainless steel). Samples of the molten salt electrolyte were taken at regular intervals throughout each run and analyzed to produce a time plot of Li{sub 2}O concentrations in the bulk salt over the course of the runs. Following each run, the fuel basket was sectioned and the fuel was removed. Samples of the fuel were analyzed for the extent of uranium oxide reduction to metal and for the concentration of salt constituents, i.e., LiCl and Li{sub 2}O. Extents of uranium oxide reduction ranged from 35 - 70% in stainless steel wire mesh baskets and 8 - 33 % in sintered stainless steel baskets. The concentrations of Li{sub 2}O in the salt phase of the fuel product from the stainless steel wire mesh baskets ranged from 6.2 to 9.3%, while

  15. Promotional effect of upper Ru oxides as methanol tolerant electrocatalyst for the oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, M.; Hernandez-Fernandez, P.; Ocon, P. [Departamento de Quimica-Fisica Aplicada C-II, Campus UAM, 28049 Madrid (Spain); Fierro, J.L.G.; Rojas, S. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, 28049 Madrid (Spain)

    2009-06-15

    The role of Ru on the oxygen reduction reaction in the presence of methanol has been investigated. To this end a series of carbon supported Pt based electrocatalysts containing Ru and Co have been prepared and thoroughly characterized. The catalytic performance on the oxygen reduction reaction (ORR) both in the presence and in the absence of methanol by linear sweep voltammetry on rotating disk electrode has been studied. In spite of its documented ability towards methanol and CO oxidation, when Ru-containing catalysts are subjected to excursions to potentials more positive than 0.8 V vs. NHE they develop a certain tolerance to the presence of methanol. This feature is attributed to the formation of upper oxide Ru species that impede the methanol oxidation reaction to occur under the typical reaction conditions of the oxygen reduction process, i.e. potentials more positive than 0.7 V vs. NHE and oxygen saturated atmospheres. The evolution of Ru species with the applied potential has been investigated by XPS, identifying the presence of upper oxidized Ru phases. (author)

  16. Sequential reduction-oxidation for photocatalytic degradation of tetrabromobisphenol A: kinetics and intermediates.

    Science.gov (United States)

    Guo, Yaoguang; Lou, Xiaoyi; Xiao, Dongxue; Xu, Lei; Wang, Zhaohui; Liu, Jianshe

    2012-11-30

    C-Br bond cleavage is considered as a key step to reduce their toxicities and increase degradation rates for most brominated organic pollutants. Here a sequential reduction/oxidation strategy (i.e. debromination followed by photocatalytic oxidation) for photocatalytic degradation of tetrabromobisphenol A (TBBPA), one of the most frequently used brominated flame retardants, was proposed on the basis of kinetic analysis and intermediates identification. The results demonstrated that the rates of debromination and even photodegradation of TBBPA strongly depended on the atmospheres, initial TBBPA concentrations, pH of the reaction solution, hydrogen donors, and electron acceptors. These kinetic data and byproducts identification obtained by GC-MS measurement indicated that reductive debromination reaction by photo-induced electrons dominated under N(2)-saturated condition, while oxidation reaction by photoexcited holes or hydroxyl radicals played a leading role when air was saturated. It also suggested that the reaction might be further optimized for pretreatment of TBBPA-contaminated wastewater by a two-stage reductive debromination/subsequent oxidative decomposition process in the UV-TiO(2) system by changing the reaction atmospheres.

  17. Revisiting the effects of organic solvents on the thermal reduction of graphite oxide

    Energy Technology Data Exchange (ETDEWEB)

    Barroso-Bujans, Fabienne, E-mail: fbarroso@ehu.es [Centro de Fisica de Materiales-Material Physics Center (CSIC-UPV/EHU), Paseo Manuel Lardizabal 5, 20018 San Sebastian (Spain); Fierro, Jose Luis G. [Instituto de Catalisis y Petroleoquimica, CSIC. Marie Curie, 2, Cantoblanco, 28049 Madrid (Spain); Alegria, Angel [Centro de Fisica de Materiales-Material Physics Center (CSIC-UPV/EHU), Paseo Manuel Lardizabal 5, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Universidad del Pais Vasco (UPV/EHU) Apartado 1072, 20080 San Sebastian (Spain); Colmenero, Juan [Centro de Fisica de Materiales-Material Physics Center (CSIC-UPV/EHU), Paseo Manuel Lardizabal 5, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Universidad del Pais Vasco (UPV/EHU) Apartado 1072, 20080 San Sebastian (Spain); Donostia International Physics Center, Paseo Manuel Lardizabal 4, 20018 San Sebastian (Spain)

    2011-11-10

    Highlights: Black-Right-Pointing-Pointer Retention of organic solvent on graphite oxide interlayer space. Black-Right-Pointing-Pointer Decreasing exfoliation temperature. Black-Right-Pointing-Pointer Close link between structure and thermal behavior of solvent treated graphite oxide. Black-Right-Pointing-Pointer Restacking inhibition of thermally reduced graphite oxide sheets. Black-Right-Pointing-Pointer Changes in kinetic mechanisms of thermal reduction. - Abstract: Treatment of graphite oxide (GO) with organic solvents via sorption from either liquid or gas phase, and subsequent desorption, induces profound changes in the layered GO structure: loss of stacking order, retention of trace amounts of solvents and decreasing decomposition temperature. This study presents new evidences of the effect of organic solvents on the thermal reduction of GO by means of thermogravimetric analysis, X-ray diffraction and X-ray photoelectron spectroscopy. The results reveal a relative higher decrease of the oxygen amounts in solvent-treated GO as compared to untreated GO and the restacking inhibition of the thermally reduced GO sheets upon slow heating. The kinetic experiments evidence changes occurring in the reduction mechanisms of the solvent-treated GO, which support the close link between GO structure and thermal properties.

  18. The azo dye Disperse Red 13 and its oxidation and reduction products showed mutagenic potential.

    Science.gov (United States)

    Chequer, Farah Maria Drumond; Lizier, Thiago Mescoloto; de Felício, Rafael; Zanoni, Maria Valnice Boldrin; Debonsi, Hosana Maria; Lopes, Norberto Peporine; de Oliveira, Danielle Palma

    2015-10-01

    Common water pollutants, azo dyes and their degradation products have frequently shown toxicity, including carcinogenic and mutagenic effects, and can induce serious damage in aquatic organisms and humans. In the present study, the mutagenic potential of the azo dye Disperse Red 13 (DR13) was first evaluated using the Micronucleus Assay in human lymphocytes. Subsequently, in order to mimic hepatic biotransformation, controlled potential electrolysis was carried out with a DR13 solution using a Potentiostat/Galvanostat. In addition, a DR13 solution was oxidized using S9 (homogenate of rat liver cells). DR13 oxidation and the reduction products were identified using HPLC-DAD and GC/MS, and their mutagenic potential investigated by way of a Salmonella/microsome assay using TA98 and YG1041 strains, with no S9. The original azo dye DR13 induced chromosomal damage in human lymphocytes, and the respective oxidation and reduction products also showed mutagenic activity, as detected by the Salmonella/microsome assay. Furthermore sulfate 2-[(4-aminophenyl)ethylamino]-ethanol monohydrate, 2-chloro-4-nitro-benzamine, 4-nitro-benzamine and 2-(ethylphenylamine)-ethanol were identified as products of the DR13 reduction/oxidation reactions. Thus it was concluded that the contamination of water effluents with DR13 is a health risk not only due to the dye itself, but also due to the possibility of drinking contaminated water, considering the harmful compounds that can be produced after hepatic biotransformation.

  19. Sequential reductive and oxidative conditions used to biodegradation of organochlorine pesticides by native bacteria.

    Science.gov (United States)

    Kopytko, M.; Correa-Torres, S. N.; Plata, A.

    2016-07-01

    Despite restrictions and bans on the use of many organochlorine pesticides in the 1970s and 1980s, they continue to persist in the environment today. This is the case of Agustin Codazzi, Cesar where the organochlorine pesticides were buried without control in the soil in 1999, after being banned their use. Nowadays is necessary to find the best method, which allows remediation of this soils. Reductive dechlorination is the first and limiting step in the metabolism of many organochlorine pesticides by anaerobic bacteria. In this study the reductive conditions were enhanced by addition of biogas as an auxiliary electron donors.The soil sample was taken from the zone at Agustin Codazzi, Cesar, and their characteristics correspond to a loam soil with low nutrient and slight compaction. The experimental tests were performed by varying the exposure time of a reducer to oxidative environment. Reductive conditions were enhanced by methane from biogas and oxidative environment was generated by air blown to stimulate a metabolic process of the soil native bacteria. Removals between 70 and 78.9% of compounds such as 4,4'-DDT, 4, 4'-DDD, 4,4'-DDE, Endrin and Trans- Chlordane, detected by gas chromatography analysis, were achieved under reductive/oxidative conditions during 120 days. Furthermore, bacterial strains capable of degrading organochlorine pesticides were selected from the native bacteria, and identified by the purified and identified based on its morphological characteristics and 16S rDNA sequencing.

  20. Fundamental study of reduction graphene oxide by sodium borohydride for gas sensor application

    Science.gov (United States)

    Muda, M. R.; Ramli, Muhammad M.; Isa, Siti S. Mat; Jamlos, M. F.; Murad, S. A. Z.; Norhanisah, Z.; Isa, M. Mohamad; Kasjoo, S. R.; Ahmad, N.; Nor, N. I. M.; Khalid, N.

    2017-03-01

    The efficient reduction of graphene oxide (rGO) was performed using Sodium Borohydride (NaBH4). These reduction approaches remove the majority of the oxygen-containing functional groups at the basal plane and surface of graphene oxide sheets. Structural and physiochemical properties of the GO were investigated with help of Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and Ultraviolet-Visible-Near infrared (UV-Vis-NIR). The effects of the chemical reduction on a GO surface were analyzed using a Semiconductor Parameter Analyzer (SPA) in order to obtain the electrical resistance measurement. It was found that the resistance of reduced graphene oxide was greatly reduced when compared to the condition of before reduction process. Then, the formation of uniform thin film of rGO sheets was produced using vacuum filtration method in order to fabricate a gas sensor. In this project, plastic was used as a substrate. The sensor was then being exposed to NO2 gas at room temperature in order to demonstrate the sensing ability of rGO.

  1. A dinuclear copper(II) electrocatalyst both water reduction and oxidation

    Science.gov (United States)

    Zhou, Ling-Ling; Fang, Ting; Cao, Jie-Ping; Zhu, Zhi-Hong; Su, Xiao-Ting; Zhan, Shu-Zhong

    2015-01-01

    Splitting water is a key challenge in the production of chemical fuels from electricity. Although several catalysts have been developed for these reactions, substantial challenges remain towards the ultimate goal of an efficient, inexpensive and robust electrocatalyst. Until now, there is as yet no report on both water oxidation and reduction by identical catalyst. Reported here is the first soluble copper-based catalyst, Cu(Me2oxpn)Cu(OH)2] 1 (Me2oxpn: N,N‧-bis(2,2‧-dimethyl-3-aminopropyl)oxamido) for both electrolytic water oxidation and reduction. Water oxidation occurs at an overpotential of 636 mV vs SHE to give O2 with a turnover frequency (TOF) of ∼2.14 s-1. Electrochemical studies also indicate that 1 is a soluble molecular species, that is among the most rapid homogeneous water reduction catalysts, with a TOF of 654 mol of hydrogen per mole of catalyst per hour at an overpotential of 789 mV vs SHE (pH 7.0). Sustained water reduction catalysis occurs at glassy carbon (GC) to give H2 over a 32 h electrolysis period with 95% Faradaic yield and no observable decomposition of the catalyst.

  2. Promotion of iron oxide reduction and extracellular electron transfer in Shewanella oneidensis by DMSO.

    Directory of Open Access Journals (Sweden)

    Yuan-Yuan Cheng

    Full Text Available The dissimilatory metal reducing bacterium Shewanella oneidensis MR-1, known for its capacity of reducing iron and manganese oxides, has great environmental impacts. The iron oxides reducing process is affected by the coexistence of alternative electron acceptors in the environment, while investigation into it is limited so far. In this work, the impact of dimethyl sulphoxide (DMSO, a ubiquitous chemical in marine environment, on the reduction of hydrous ferric oxide (HFO by S. oneidensis MR-1 was investigated. Results show that DMSO promoted HFO reduction by both wild type and ΔdmsE, but had no effect on the HFO reduction by ΔdmsB, indicating that such a promotion was dependent on the DMSO respiration. With the DMSO dosing, the levels of extracellular flavins and omcA expression were significantly increased in WT and further increased in ΔdmsE. Bioelectrochemical analysis show that DMSO also promoted the extracellular electron transfer of WT and ΔdmsE. These results demonstrate that DMSO could stimulate the HFO reduction through metabolic and genetic regulation in S. oneidensis MR-1, rather than compete for electrons with HFO. This may provide a potential respiratory pathway to enhance the microbial electron flows for environmental and engineering applications.

  3. DICP's New Technology for Manufacture of Propylene Oxide through Direct Oxidation of Propylene by Hydrogen Peroxide Passed Appraisal

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ In August 2008 the new technology for manufacture of pro-pylene oxide through direct oxidation of propylene by hy-drogen peroxide developed by Dalian Institute of Chemical Physics (DICP), CAS has passed the experts' appraisal or-ganized by the Science and Technology Department of Liaoning Province. It is told that this new technology, being an environmentally friendly new process, will eventually put an end to the severe pollution characteristic of the tradi-tional propylene oxide production process.

  4. Self-propagating solar light reduction of graphite oxide in water

    Science.gov (United States)

    Todorova, N.; Giannakopoulou, T.; Boukos, N.; Vermisoglou, E.; Lekakou, C.; Trapalis, C.

    2017-01-01

    Graphite Oxide (GtO) is commonly used as an intermediate material for preparation of graphene in the form of reduced graphene oxide (rGO). Being a semiconductor with tunable band gap rGO is often coupled with various photocatalysts to enhance their visible light activity. The behavior of such rGO-based composites could be affected after prolonged exposure to solar light. In the present work, the alteration of the GtO properties under solar light irradiation is investigated. Water dispersions of GtO manufactured by oxidation of natural graphite via Hummers method were irradiated into solar light simulator for different periods of time without addition of catalysts or reductive agent. The FT-IR analysis of the treated dispersions revealed gradual reduction of the GtO with the increase of the irradiation time. The XRD, FT-IR and XPS analyses of the obtained solid materials confirmed the transition of GtO to rGO under solar light irradiation. The reduction of the GtO was also manifested by the CV measurements that revealed stepwise increase of the specific capacitance connected with the restoration of the sp2 domains. Photothermal self-propagating reduction of graphene oxide in aqueous media under solar light irradiation is suggested as a possible mechanism. The self-photoreduction of GtO utilizing solar light provides a green, sustainable route towards preparation of reduced graphene oxide. However, the instability of the GtO and partially reduced GO under irradiation should be considered when choosing the field of its application.

  5. Reduction efficiency prediction of CENIBRA's recovery boiler by direct minimization of gibbs free energy

    Directory of Open Access Journals (Sweden)

    W. L. Silva

    2008-09-01

    Full Text Available The reduction efficiency is an important variable during the black liquor burning process in the Kraft recovery boiler. This variable value is obtained by slow experimental routines and the delay of this measure disturbs the pulp and paper industry customary control. This paper describes an optimization approach for the reduction efficiency determination in the furnace bottom of the recovery boiler based on the minimization of the Gibbs free energy. The industrial data used in this study were directly obtained from CENIBRA's data acquisition system. The resulting approach is able to predict the steady state behavior of the chemical composition of the furnace recovery boiler, - especially the reduction efficiency when different operational conditions are used. This result confirms the potential of this approach in the analysis of the daily operation of the recovery boiler.

  6. Direct electrochemistry and electrocatalysis of hemoglobin in graphene oxide and ionic liquid composite film

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Wei, E-mail: swyy26@hotmail.com [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Gong, Shixing [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Shi, Fan [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Cao, Lili; Ling, Luyang [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Zheng, Weizhe; Wang, Wencheng [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China)

    2014-07-01

    In this paper a novel sensing platform based on graphene oxide (GO), ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate and Nafion for the immobilization of hemoglobin (Hb) was adopted with a carbon ionic liquid electrode (CILE) as the substrate electrode, which was denoted as Nafion/Hb–GO–IL/CILE. Spectroscopic results suggested that Hb molecules were not denatured in the composite. A pair of well-defined redox peaks appeared on the cyclic voltammogram, which was attributed to the realization of direct electron transfer of Hb on the electrode. Electrochemical behaviors of Hb entrapped in the film were carefully investigated by cyclic voltammetry with the electrochemical parameters calculated. Based on the catalytic ability of the immobilized Hb, Nafion/Hb–GO–IL/CILE exhibited excellent electrocatalytic behavior towards the reduction of different substrates such as trichloroacetic acid in the concentration range from 0.01 to 40.0 mM with the detection limit as 3.12 μM (3σ), H{sub 2}O{sub 2} in the concentration range from 0.08 to 635.0 μM with the detection limit as 0.0137 μM (3σ) and NaNO{sub 2} in the concentration range from 0.5 to 800.0 μM with the detection limit as 0.0104 μM (3σ). So the proposed bioelectrode could be served as a new third-generation electrochemical sensor without mediator. - Highlights: • A graphene oxide, 1-ethyl-3-methylimidazolium tetrafluoroborate and hemoglobin composite were prepared. • Composite modified carbon ionic liquid electrode was fabricated. • Direct electrochemistry of hemoglobin was realized on the modified electrode. • Bioelectrocatalytic reduction of the modified electrode to different substrates was studied.

  7. The reduction and oxidation of ceria: A natural abundance triple oxygen isotope perspective

    Science.gov (United States)

    Hayles, Justin; Bao, Huiming

    2015-06-01

    Ceria (CeO2) is a heavily studied material in catalytic chemistry for use as an oxygen storage medium, oxygen partial pressure regulator, fuel additive, and for the production of syngas, among other applications. Ceria powders are readily reduced and lose structural oxygen when subjected to low pO2 and/or high temperature conditions. Such dis-stoichiometric ceria can then re-oxidize under higher pO2 and/or lower temperature by incorporating new oxygen into the previously formed oxygen site vacancies. Despite extensive studies on ceria, the mechanisms for oxygen adsorption-desorption, dissociation-association, and diffusion of oxygen species on ceria surface and within the crystal structure are not well known. We predict that a large kinetic oxygen isotope effect should accompany the release and incorporation of ceria oxygen. As the first attempt to determine the existence and the degree of the isotope effect, this study focuses on a set of simple room-temperature re-oxidation experiments that are also relevant to a laboratory procedure using ceria to measure the triple oxygen isotope composition of CO2. Triple-oxygen-isotope labeled ceria powders are heated at 700 °C and cooled under vacuum prior to exposure to air. By combining results from independent experimental sets with different initial oxygen isotope labels and using a combined mass-balance and triangulation approach, we have determined the isotope fractionation factors for both high temperature reduction in vacuum (⩽10-4 mbar) and room temperature re-oxidation in air. Results indicate that there is a 1.5‰ ± 0.8‰ increase in the δ18O value of ceria after being heated in vacuum at 700 °C for 1 h. When the vacuum is broken at room temperature, the previously heated ceria incorporates 3-19% of its final structural oxygen from air, with a δ18O value of 2.1-4.1+7.7 ‰ for the incorporated oxygen. The substantial incorporation of oxygen from air supports that oxygen mobility is high in vacancy

  8. Reduction of nickel oxide particles by hydrogen studied in an environmental TEM

    DEFF Research Database (Denmark)

    Jeangros, Q.; Hansen, Thomas Willum; Wagner, Jakob Birkedal;

    2013-01-01

    In situ reduction of nickel oxide (NiO) particles is performed under 1.3 mbar of hydrogen gas (H2) in an environmental transmission electron microscope (ETEM). Images, diffraction patterns and electron energy-loss spectra (EELS) are acquired to monitor the structural and chemical evolution...... of the system during reduction, whilst increasing the temperature. Ni nucleation on NiO is either observed to be epitaxial or to involve the formation of randomly oriented grains. The growth of Ni crystallites and the movement of interfaces result in the formation of pores within the NiO grains to accommodate...... the volume shrinkage associated with the reduction. Densification is then observed when the sample is nearly fully reduced. The reaction kinetics is obtained using EELS by monitoring changes in the shapes of the Ni L2,3 white lines. The activation energy for NiO reduction is calculated from the EELS data...

  9. Complete relaxation of residual stresses during reduction of solid oxide fuel cells

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Chatzichristodoulou, Christodoulos; Hendriksen, Peter Vang

    2015-01-01

    reduce significantly over minutes. In this work the stresses are measured in-situ before and after the reduction by use of XRD. The phenomenon of accelerated creep has to be considered both in the production of stacks and in the analysis of the stress field in a stack based on anode supported SOFCs.......To asses the reliability of solid oxide fuel cell (SOFC) stacks during operation, the stress field in the stack must be known. During operation the stress field will depend on time as creep processes relax stresses. This work reports further details on a newly discovered creep phenomenon......, accelerated creep, taking place during the reduction of the anode. This relaxes stresses at a much higher rate (~×104) than creep during operation. The phenomenon has previously been studied by simultaneous loading and reduction. With the recorded high creep rates, the stresses at the time of reduction should...

  10. Coupled mercury-cell sorption, reduction, and oxidation on methylmercury production by Geobacter sulfurreducens PCA.

    Science.gov (United States)

    Lin, Hui; Morrell-Falvey, Jennifer L; Rao, Balaji; Liang, Liyuan; Gu, Baohua

    2014-10-21

    G. sulfurreducens PCA cells have been shown to reduce, sorb, and methylate Hg(II) species, but it is unclear whether this organism can oxidize and methylate dissolved elemental Hg(0) as shown for Desulfovibrio desulfuricans ND132. Using Hg(II) and Hg(0) separately as Hg sources in washed cell assays in phosphate buffered saline (pH 7.4), we report how cell-mediated Hg reduction and oxidation compete or synergize with sorption, thus affecting the production of toxic methylmercury by PCA cells. Methylation is found to be positively correlated to Hg sorption (r = 0.73) but negatively correlated to Hg reduction (r = -0.62). These reactions depend on the Hg and cell concentrations or the ratio of Hg to cellular thiols (-SH). Oxidation and methylation of Hg(0) are favored at relatively low Hg to cell-SH molar ratios (e.g., <1). Increasing Hg to cell ratios from 0.25 × 10(-19) to 25 × 10(-19) moles-Hg/cell (equivalent to Hg/cell-SH of 0.71 to 71) shifts the major reaction from oxidation to reduction. In the absence of five outer membrane c-type cytochromes, mutant ΔomcBESTZ also shows decreases in Hg reduction and increases in methylation. However, the presence of competing thiol-binding ions such as Zn(2+) leads to increased Hg reduction and decreased methylation. These results suggest that the coupled cell-Hg sorption and redox transformations are important in controlling the rates of Hg uptake and methylation by G. sulfurreducens PCA in anoxic environments.

  11. Interactions Between Fe(III)-oxides and Fe(III)-phyllosilicates During Microbial Reduction 2: Natural Subsurface Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Wu, T.; Griffin, A. M.; Gorski, C. A.; Shelobolina, E. S.; Xu, H.; Kukkadapu, R. K.; Roden, E. E.

    2016-04-19

    Dissimilatory microbial reduction of solid-phase Fe(III)-oxides and Fe(III)-bearing phyllosilicates (Fe(III)-phyllosilicates) is an important process in anoxic soils, sediments, and subsurface materials. Although various studies have documented the relative extent of microbial reduction of single-phase Fe(III)-oxides and Fe(III)-phyllosilicates, detailed information is not available on interaction between these two processes in situations where both phases are available for microbial reduction. The goal of this research was to use the model dissimilatory iron-reducing bacterium (DIRB) Geobacter sulfurreducens to study Fe(III)-oxide vs. Fe(III)-phyllosilicate reduction in a range of subsurface materials and Fe(III)-oxide stripped versions of the materials. Low temperature (12K) Mossbauer spectroscopy was used to infer changes in the relative abundances of Fe(III)-oxide, Fe(III)-phyllosilicate, and phyllosilicate-associated Fe(II) (Fe(II)-phyllosilicate). A Fe partitioning model was employed to analyze the fate of Fe(II) and assess the potential for abiotic Fe(II)-catalyzed reduction of Fe(III)-phyllosilicates. The results showed that in most cases Fe(III)- oxide utilization dominated (70-100 %) bulk Fe(III) reduction activity, and that electron transfer from oxide-derived Fe(II) played only a minor role (ca. 10-20 %) in Fe partitioning. In addition, the extent of Fe(III)-oxide reduction was positively correlated to surface area-normalized cation exchange capacity and the phyllosilicate-Fe(III)/total Fe(III) ratio, which suggests that the phyllosilicates in the natural sediments promoted Fe(III)-oxide reduction by binding of oxide-derived Fe(II), thereby enhancing Fe(III)-oxide reduction by reducing or delaying the inhibitory effect that Fe(II) accumulation on oxide and DIRB cell surfaces has on Fe(III)-oxide reduction. In general our results suggest that although Fe(III)-oxide reduction is likely to dominate bulk Fe(III) reduction in most subsurface sediments, Fe

  12. The Reduction of Aqueous Metal Species on the Surfaces of Fe(II)-Containing Oxides: The Role of Surface Passivation

    Science.gov (United States)

    White, A.F.; Peterson, M.L.

    1998-01-01

    The reduction of aqueous transition metal species at the surfaces of Fe(II)- containing oxides has important ramifications in predicting the transport behavior in ground water aquifers. Experimental studies using mineral suspensions and electrodes demonstrate that structural Fe(II) heterogeneously reduces aqueous ferric, cupric, vanadate and chromate ions on magnetite and ilmenite surfaces. The rates of metal reduction on natural oxides is strongly dependent on the extent of surface passivation and redox conditions in the weathering environment. Synchrotron studies show that surface oxidation of Fe(II)-containing oxide minerals decreases their capacity for Cr(VI) reduction at hazardous waste disposal sites.

  13. Microbial Fe(III) oxide reduction potential in Chocolate Pots hot spring, Yellowstone National Park.

    Science.gov (United States)

    Fortney, N W; He, S; Converse, B J; Beard, B L; Johnson, C M; Boyd, E S; Roden, E E

    2016-05-01

    Chocolate Pots hot springs (CP) is a unique, circumneutral pH, iron-rich, geothermal feature in Yellowstone National Park. Prior research at CP has focused on photosynthetically driven Fe(II) oxidation as a model for mineralization of microbial mats and deposition of Archean banded iron formations. However, geochemical and stable Fe isotopic data have suggested that dissimilatory microbial iron reduction (DIR) may be active within CP deposits. In this study, the potential for microbial reduction of native CP Fe(III) oxides was investigated, using a combination of cultivation dependent and independent approaches, to assess the potential involvement of DIR in Fe redox cycling and associated stable Fe isotope fractionation in the CP hot springs. Endogenous microbial communities were able to reduce native CP Fe(III) oxides, as documented by most probable number enumerations and enrichment culture studies. Enrichment cultures demonstrated sustained DIR driven by oxidation of acetate, lactate, and H2 . Inhibitor studies and molecular analyses indicate that sulfate reduction did not contribute to observed rates of DIR in the enrichment cultures through abiotic reaction pathways. Enrichment cultures produced isotopically light Fe(II) during DIR relative to the bulk solid-phase Fe(III) oxides. Pyrosequencing of 16S rRNA genes from enrichment cultures showed dominant sequences closely affiliated with Geobacter metallireducens, a mesophilic Fe(III) oxide reducer. Shotgun metagenomic analysis of enrichment cultures confirmed the presence of a dominant G. metallireducens-like population and other less dominant populations from the phylum Ignavibacteriae, which appear to be capable of DIR. Gene (protein) searches revealed the presence of heat-shock proteins that may be involved in increased thermotolerance in the organisms present in the enrichments as well as porin-cytochrome complexes previously shown to be involved in extracellular electron transport. This analysis offers

  14. Direct 2-acetoxylation of quinoline N-oxides via copper catalyzed C-H bond activation.

    Science.gov (United States)

    Chen, Xuan; Zhu, Chongwei; Cui, Xiuling; Wu, Yangjie

    2013-08-07

    An efficient and direct 2-acetoxylation of quinoline N-oxides via copper(I) catalyzed C-H bond activation has been developed. This transformation was achieved using TBHP as an oxidant in the cross-dehydrogenative coupling (CDC) reaction of quinoline N-oxides with aldehydes, and provided a practical pathway to 2-acyloxyl quinolines.

  15. Mitochondrial isocitrate dehydrogenase is inactivated upon oxidation and reactivated by thioredoxin-dependent reduction in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Keisuke eYoshida

    2014-09-01

    Full Text Available Regulation of mitochondrial metabolism is essential for ensuring cellular growth and maintenance in plants. Based on redox-proteomics analysis, several proteins involved in diverse mitochondrial reactions have been identified as potential redox-regulated proteins. NAD+-dependent isocitrate dehydrogenase (IDH, a key enzyme in the tricarboxylic acid cycle, is one such candidate. In this study, we investigated the redox regulation mechanisms of IDH by biochemical procedures. In contrast to mammalian and yeast counterparts reported to date, recombinant IDH in Arabidopsis mitochondria did not show adenylate-dependent changes in enzymatic activity. Instead, IDH was inactivated by oxidation treatment and partially reactivated by subsequent reduction. Functional IDH forms a heterodimer comprising regulatory (IDH-r and catalytic (IDH-c subunits. IDH-r was determined to be the target of oxidative modifications forming an oligomer via intermolecular disulfide bonds. Mass spectrometric analysis combined with tryptic digestion of IDH-r indicated that Cys128 and Cys216 are involved in intermolecular disulfide bond formation. Furthermore, we showed that mitochondria-localized o-type thioredoxin (Trx-o promotes the reduction of oxidized IDH-r. These results suggest that IDH-r is susceptible to oxidative stress, and Trx-o serves to convert oxidized IDH-r to the reduced form that is necessary for active IDH complex.

  16. Direct Similarity Reduction and New Exact Solutions for the Variable-Coefficient Kadomtsev-Petviashvili Equation

    Science.gov (United States)

    El-Shiekh, Rehab M.

    2015-06-01

    In this paper, the generalized (3+1)-dimensional variable-coefficient Kadomtsev-Petviashvili equation (VCKPE), which can describe nonlinear phenomena in fluids or plasmas, is studied by using two different Clarkson and Kruskal (CK) direct methods, namely, the classical CK and the modified enlarged CK method. A similarity reduction to a (2+1)-dimensional nonlinear partial differential equation and a direct similarity reduction to a nonlinear ordinary differential equation are obtained, respectively. By solving the reduced ordinary differential equation, new solitary, periodic, and singular solutions for the VCKPE are obtained. Some figures for the soliton and periodic wave solutions are given to reflect the effect of the variable coefficients on the solution propagation. Finally, the comparison between the two different CK techniques indicates that the modified enlarged CK technique is clearly more powerful and simple than the classical CK technique.

  17. Direct measurements of nitric oxide release in relation to expression of endothelial nitric oxide synthase in isolated porcine mitral valves

    DEFF Research Database (Denmark)

    Moesgaard, Sophia Gry; Olsen, Lisbeth Høier; Aasted, Bent;

    2007-01-01

    The aim of this study was to measure the direct release of nitric oxide (NO) from the porcine mitral valve using a NO microelectrode. Furthermore, the expression and localization of endothelial nitric oxide synthase (eNOS) in the mitral valve was studied using immunohistochemistry, Western blotting...

  18. Advanced Manufacturing of Intermediate Temperature, Direct Methane Oxidation Membrane Electrode Assemblies for Durable Solid Oxide Fuel Cell Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation builds on the successes of the Phase I program by integrating our direct oxidation membrane electrode assembly (MEA) into a monolithic solid...

  19. Comparison of Direct Solar Energy to Resistance Heating for Carbothermal Reduction of Regolith

    Science.gov (United States)

    Muscatello, Anthony C.; Gustafson, Robert J.

    2011-01-01

    A comparison of two methods of delivering thermal energy to regolith for the carbo thermal reduction process has been performed. The comparison concludes that electrical resistance heating is superior to direct solar energy via solar concentrators for the following reasons: (1) the resistance heating method can process approximately 12 times as much regolith using the same amount of thermal energy as the direct solar energy method because of superior thermal insulation; (2) the resistance heating method is more adaptable to nearer-term robotic exploration precursor missions because it does not require a solar concentrator system; (3) crucible-based methods are more easily adapted to separation of iron metal and glass by-products than direct solar energy because the melt can be poured directly after processing instead of being remelted; and (4) even with projected improvements in the mass of solar concentrators, projected photovoltaic system masses are expected to be even lower.

  20. Bifunctional Catalysis: Direct Reductive Amination of Aliphatic Ketones with an Iridium-Phosphate Catalyst

    Directory of Open Access Journals (Sweden)

    Barbara Villa-Marcos

    2010-04-01

    Full Text Available Chiral amines are one of the ubiquitous functional groups in fine chemical, pharmaceutical and agrochemical products, and the most convenient, economical, and eco-benign synthetic pathway to these amines is direct asymmetric reductive amination (DARA of prochiral ketones. This paper shows that a wide range of aliphatic ketones can be directly aminated under hydrogenation conditions, affording chiral amines with good to excellent yields and with enantioselectivities up to 96% ee. The catalysis is effected by the cooperative action of a cationic Cp*Ir(III complex and its phosphate counteranion.

  1. Noise Reduction of MEMS Gyroscope Based on Direct Modeling for an Angular Rate Signal

    OpenAIRE

    Liang Xue; Chengyu Jiang; Lixin Wang; Jieyu Liu; Weizheng Yuan

    2015-01-01

    In this paper, a novel approach for processing the outputs signal of the microelectromechanical systems (MEMS) gyroscopes was presented to reduce the bias drift and noise. The principle for the noise reduction was presented, and an optimal Kalman filter (KF) was designed by a steady-state filter gain obtained from the analysis of KF observability. In particular, the true angular rate signal was directly modeled to obtain an optimal estimate and make a self-compensation for the gyroscope witho...

  2. NOx reduction by ozone injection and direct plasma treatment

    OpenAIRE

    Stamate, Eugen; Salewski, Mirko

    2012-01-01

    NOx reduction by ozone injection and direct plasma treatment is investigated for different process parameters in a 6 m long serpentine reactor. Several aspects including the role of mixing scheme, water vapours, steep temperature gradient and time dependet NOx levels are taken into consideration. The process chemistry is monitored by FTIR, chemiluminiscence and absorbtion spectroscopy. The kinetic mechanism is also investigated in 3D simulations.

  3. Solid-phase electrochemical reduction of graphene oxide films in alkaline solution

    Science.gov (United States)

    Basirun, Wan J.; Sookhakian, Mehran; Baradaran, Saeid; Mahmoudian, Mohammad R.; Ebadi, Mehdi

    2013-09-01

    Graphene oxide (GO) film was evaporated onto graphite and used as an electrode to produce electrochemically reduced graphene oxide (ERGO) films by electrochemical reduction in 6 M KOH solution through voltammetric cycling. Fourier transformed infrared and Raman spectroscopy confirmed the presence of ERGO. Electrochemical impedance spectroscopy characterization of ERGO and GO films in ferrocyanide/ferricyanide redox couple with 0.1 M KCl supporting electrolyte gave results that are in accordance with previous reports. Based on the EIS results, ERGO shows higher capacitance and lower charge transfer resistance compared to GO.

  4. Reduction in nitrogen oxides emission on TGME-464 boiler of IRU power plant (Estonia)

    Science.gov (United States)

    Roslyakov, P. V.; Ionkin, I. L.

    2015-01-01

    The possibility for realization of measures on a reduction in nitrogen oxides emission on a TGME-464 (plant no. 2) boiler of the IRU power plant (Tallinn, Estonia) is investigated. Low-cost techno-logical measures, namely, nonstoichiometric burning and burning with the moderate controlled chemical underburning, are proposed and experimentally tested. Recommendations on the implementation of low-emission modes of burning natural gas into mode diagrams of the boiler are given. Nitrogen oxides emissions are reduced to the required level as a result of the implementation of the proposed measures.

  5. Graphene transistors via in situ voltage-induced reduction of graphene-oxide under ambient conditions.

    Science.gov (United States)

    Mativetsky, Jeffrey M; Liscio, Andrea; Treossi, Emanuele; Orgiu, Emanuele; Zanelli, Alberto; Samorì, Paolo; Palermo, Vincenzo

    2011-09-14

    Here, we describe a simple approach to fabricate graphene-based field-effect-transistors (FETs), starting from aqueous solutions of graphene-oxide (GO), processed entirely under ambient conditions. The process relies on the site-selective reduction of GO sheets deposited in between or on the surface of micro/nanoelectrodes. The same electrodes are first used for voltage-induced electrochemical GO reduction, and then as the source and drain contacts of FETs, allowing for the straightforward production and characterization of ambipolar graphene devices. With the use of nanoelectrodes, we could reduce different selected areas belonging to one single sheet as well.

  6. Biotic and abiotic oxidation and reduction of iron at circumneutral pH are inseparable processes under natural conditions

    NARCIS (Netherlands)

    Ionescu, Danny; Heim, Christine; Polerecky, L.|info:eu-repo/dai/nl/370827929; Thiel, Volker; de Beer, Dirk

    2015-01-01

    Oxidation and reduction of iron can occur through abiotic (chemical) and biotic (microbial) processes. Abiotic iron oxidation is a function of pH and O2 concentration. Biotic iron oxidation is carried out by a diverse group of bacteria, using O2 or NO3 as terminal electron acceptors. At circumneutra

  7. Biotic and abiotic oxidation and reduction of iron at circumneutral pH are inseparable processes under natural conditions

    NARCIS (Netherlands)

    Ionescu, Danny; Heim, Christine; Polerecky, L.; Thiel, Volker; de Beer, Dirk

    2015-01-01

    Oxidation and reduction of iron can occur through abiotic (chemical) and biotic (microbial) processes. Abiotic iron oxidation is a function of pH and O2 concentration. Biotic iron oxidation is carried out by a diverse group of bacteria, using O2 or NO3 as terminal electron acceptors. At circumneutra

  8. Going wireless: Fe(III) oxide reduction without pili by Geobacter sulfurreducens strain JS-1.

    Science.gov (United States)

    Smith, Jessica A; Tremblay, Pier-Luc; Shrestha, Pravin Malla; Snoeyenbos-West, Oona L; Franks, Ashley E; Nevin, Kelly P; Lovley, Derek R

    2014-07-01

    Previous studies have suggested that the conductive pili of Geobacter sulfurreducens are essential for extracellular electron transfer to Fe(III) oxides and for optimal long-range electron transport through current-producing biofilms. The KN400 strain of G. sulfurreducens reduces poorly crystalline Fe(III) oxide more rapidly than the more extensively studied DL-1 strain. Deletion of the gene encoding PilA, the structural pilin protein, in strain KN400 inhibited Fe(III) oxide reduction. However, low rates of Fe(III) reduction were detected after extended incubation (>30 days) in the presence of Fe(III) oxide. After seven consecutive transfers, the PilA-deficient strain adapted to reduce Fe(III) oxide as fast as the wild type. Microarray, whole-genome resequencing, proteomic, and gene deletion studies indicated that this adaptation was associated with the production of larger amounts of the c-type cytochrome PgcA, which was released into the culture medium. It is proposed that the extracellular cytochrome acts as an electron shuttle, promoting electron transfer from the outer cell surface to Fe(III) oxides. The adapted PilA-deficient strain competed well with the wild-type strain when both were grown together on Fe(III) oxide. However, when 50% of the culture medium was replaced with fresh medium every 3 days, the wild-type strain outcompeted the adapted strain. A possible explanation for this is that the necessity to produce additional PgcA, to replace the PgcA being continually removed, put the adapted strain at a competitive disadvantage, similar to the apparent selection against electron shuttle-producing Fe(III) reducers in many anaerobic soils and sediments. Despite increased extracellular cytochrome production, the adapted PilA-deficient strain produced low levels of current, consistent with the concept that long-range electron transport through G. sulfurreducens biofilms is more effective via pili.

  9. Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires

    Directory of Open Access Journals (Sweden)

    Emanuele Francesco Marano

    2017-02-01

    Full Text Available Metallic porous microtubes were obtained from commercial wires (200–250 µm diameter of Cu-65Ni-2Fe, Cu-44Ni-1Mn and Cu-23Ni, alloys (wt. % by surface oxidation at 1173 K in air, removal of the unoxidized core by chemical etching, and reduction in annealing in the hydrogen atmosphere. Transversal sections of the partially oxidized wires show a porous layered structure, with an external shell of CuO (about 10 μm thick and an inner layer of NiO (70–80 μm thick. In partially oxidized Cu-44Ni-1Mn and Cu-23Ni, Cu2O is dispersed in NiO because the maximum solubility of Cu in NiO is exceeded, whereas in Cu-65Ni-2Fe, a Cu2O shell is present between CuO and NiO layers. Chemical etching removed the unoxidized metallic core and Cu2O with formation of porous oxide microtubes. Porosity increases with Cu content because of the larger amount of Cu2O in the partially oxidized wire. After reduction, the transversal sections of the metallic porous microtubes show a series of f.c.c.-(Cu,Ni solid solutions with different compositions, due to the segregation of CuO and NiO during oxidation caused by the different diffusion coefficients of Ni and Cu in the respective oxides. Pore formation occurs at each step of the process because of the Kirkendall effect, selective phase removal and volume contraction.

  10. Progress of reduction methods of graphene oxide%氧化石墨烯还原方法的研究进展

    Institute of Scientific and Technical Information of China (English)

    吴婕

    2013-01-01

      石墨烯的制备对于石墨烯的理论研究和应用研究起着重要的作用,化学氧化还原法是制备石墨烯最为重要的方法之一。综述了近年来氧化石墨烯的还原剂还原法、高温热处理还原法、电化学还原法、溶剂热还原法、催化还原法、微波还原法等多种还原方法,分析了目前各种常用还原方法的优缺点,并进一步提出氧化石墨烯还原方法未来的几个研究方向:还原前后原子结构变化及还原机理研究;新型还原方法或多种还原方法联用的研究;还原氧化石墨烯和制备复合物同时进行的研究。%Preparation of graphene plays an important role in theoretical and applied research of graphene. Chemical reduction of exfoliated graphite oxide (graphene oxide) appears to be one of the most important routes for graphene production available at present. In this paper,reduction methods of graphene oxide,such as using reducing agent reduction,thermal treatment reduction,electrochemical reduction,solvothermal reduction,catalytic reduction and microwave reduction are summarized,and the advantages and disadvantages are also analyzed. The research directions of the reduction methods of graphene oxide are discussed,such as changes in atomic structure after reduction and reduction mechanism,new reduction method and integration of two or more reduction methods,simultaneous reduction of graphene oxide and preparation of compounded graphene.

  11. Cu and Co exchanged ZSM-5 zeolites: activity towards no reduction and hydrocarbon oxidation

    Directory of Open Access Journals (Sweden)

    Martins Leandro

    2006-01-01

    Full Text Available |Cu x|[Si yAl]-MFI and |Co x|[Si yAl]-MFI catalysts were prepared by ion exchange from |Na|[Si yAl]-MFI zeolites (y = 12, 25 and 45. The activity of the catalysts was evaluated in the reduction of NO to N2 in an oxidative atmosphere using propane or methane as reducing agents. The Cu catalysts were only active with propane and they presented higher activity than the Co-based catalysts, the latter being active with both hydrocarbons. H2-TPR and DRS-UV/Vis data allowed correlation between the activity towards NO reduction and the presence of cationic charge-compensating species in the zeolite. It was also verified that the hydrocarbons are preferentially oxidised by O2, a reaction that occurs simultaneously with their oxidation with NO.

  12. Combining Chemical Oxidation and Enhanced Reductive Dechlorination for DNAPL Source Area Treatment at a Danish Megasite

    DEFF Research Database (Denmark)

    Christophersen, Mette; Christensen, Jørgen F; Durant, Neal D

    beneath two of the waste pits (Pits 1 and 2). Technologies included in the bench test were chemical oxidation using modified Fenton’s reagent, MFR (hydrogen peroxide + chelated Fe2+), chemical oxidation using activated sodium persulfate (ASP) and biological enhanced reductive dechlorination (ERD) via......) consists of a closed-loop groundwater recirculation cell (25 m long) in which electron donor (lactate and ethanol) is delivered to the treatment zone via forced gradient flow field. Performance is monitored in a series of wells located between the injection and extraction wells. Results. Despite very high...... contaminant concentrations, soil samples collected after the 2nd MFR injection event in Pit 1 showed a significant reduction in contaminant concentrations. Water analyses showed that the concentrations of organic contaminants still are very high and that metals were mobilized. Lead and copper were found...

  13. Recovery of Ferric Oxide from Bayer Red Mud by Reduction Roasting-Magnetic Separation Process

    Institute of Scientific and Technical Information of China (English)

    LIU Yanjie; ZUO Kesheng; YANG Guang; SHANG Zhe; ZHANG Jianbin

    2016-01-01

    A great amount of red mud generated from alumina production by Bayer process was considered as a low-grade iron ore with a grade of 5wt% to 30wt% iron. We adopted the reduction roasting-magnetic separation process to recover ferric oxide from red mud. The red mud samples were processed by reduction roasting, grinding and magnetic separating respectively. The effects of different parameters on the recovery rate of iron were studied in detail. The optimum techqical parameters were proposed with 700℃ roasting for 20 min, as 50wt% carbon and 4wt% additive were added. The experimental results indicated that the iron recovery and the grade of total iron were 91% and 60%, respectively. A novel process is applicable to recover ferric oxide from the red mud waste ifnes.

  14. Laser-assisted reduction of graphene oxide for paper based large area flexible electronics

    Science.gov (United States)

    Balliu, E.; Andersson, H.; Engholm, M.; Forsberg, S.; Olin, H.

    2016-03-01

    In this work we present a promising method for fabrication of conductive tracks on paper based substrates by laser assisted reduction of Graphene Oxide (GO). Printed electronics on paper based substrates is be coming more popular due to lower cost and recyclability. Fabrication of conductive tracks is of great importance where metal, carbon and polymer inks are commonly used. An emerging option is reduced graphene oxide (r-GO), which can be a good conductor. Here we have evaluated reduction of GO by using a 532 nm laser source, showing promising results with a decrease of sheet resistance from >100 M Ω/Sqr for unreduced GO down to 126 Ω/Sqr. without any observable damage to the paper substrates.

  15. Standard test method for measurement of oxidation-reduction potential (ORP) of soil

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers a procedure and related test equipment for measuring oxidation-reduction potential (ORP) of soil samples removed from the ground. 1.2 The procedure in Section 9 is appropriate for field and laboratory measurements. 1.3 Accurate measurement of oxidation-reduction potential aids in the analysis of soil corrosivity and its impact on buried metallic structure corrosion rates. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  16. Reduction of blood nitric oxide levels is associated with clinical improvement of the chronic pelvic pain related to endometriosis

    Directory of Open Access Journals (Sweden)

    M.G. Rocha

    2015-04-01

    Full Text Available The objective of this prospective study was to determine the plasma levels of nitric oxide (NO in women with chronic pelvic pain secondary to endometriosis (n=24 and abdominal myofascial pain syndrome (n=16. NO levels were measured in plasma collected before and 1 month after treatment. Pretreatment NO levels (μM were lower in healthy volunteers (47.0±12.7 than in women with myofascial pain (64.2±5.0, P=0.01 or endometriosis (99.5±12.9, P<0.0001. After treatment, plasma NO levels were reduced only in the endometriosis group (99.5±12.9 vs 61.6±5.9, P=0.002. A correlation between reduction of pain intensity and reduction of NO level was observed in the endometriosis group [correlation = 0.67 (95%CI = 0.35 to 0.85, P<0.0001]. Reduction of NO levels was associated with an increase of pain threshold in this group [correlation = -0.53 (-0.78 to -0.14, P<0.0001]. NO levels appeared elevated in women with chronic pelvic pain diagnosed as secondary to endometriosis, and were directly associated with reduction in pain intensity and increase in pain threshold after treatment. Further studies are needed to investigate the role of NO in the pathophysiology of pain in women with endometriosis and its eventual association with central sensitization.

  17. Graphenothermal reduction synthesis of 'exfoliated graphene oxide/iron (II) oxide' composite for anode application in lithium ion batteries

    Science.gov (United States)

    Petnikota, Shaikshavali; Marka, Sandeep Kumar; Banerjee, Arkaprabha; Reddy, M. V.; Srikanth, V. V. S. S.; Chowdari, B. V. R.

    2015-10-01

    Graphenothermal Reduction process is used to obtain exfoliated graphene oxide (EG)/iron (II) oxide (FeO) composite prepared at 650 °C for 5 h in argon. Structural and compositional analyses of the sample confirm the formation of EG/FeO composite. This composite shows a reversible capacity of 857 mAh g-1 at a current rate of 50 mA g-1 in the voltage range 0.005-3.0 V versus Li. An excellent capacity retention up to 60 cycles and high coulombic efficiency of 98% are also observed. Characteristic Fe2+/0 redox peaks observed in Cyclic Voltammetry measurement are explained in correlation with lithium storage mechanism. Thermal, electrical and impedance spectroscopy studies of EG/FeO composite are discussed in detail. Comparative electrochemical cycling studies of EG/FeO composite with Fe2O3 and Fe3O4 materials prepared under controlled conditions are also discussed.

  18. pH dependence of proton translocation in the oxidative and reductive phases of the catalytic cycle of cytochrome c oxidase. The role of H2O produced at the oxygen-reduction site.

    Science.gov (United States)

    Capitanio, Giuseppe; Martino, Pietro Luca; Capitanio, Nazzareno; De Nitto, Emanuele; Papa, Sergio

    2006-02-14

    A study is presented on the pH dependence of proton translocation in the oxidative and reductive phases of the catalytic cycle of purified cytochrome c oxidase (COX) from beef heart reconstituted in phospholipid vesicles (COV). Protons were shown to be released from COV both in the oxidative and reductive phases. In the oxidation by O2 of the fully reduced oxidase, the H+/COX ratio for proton release from COV (R --> O transition) decreased from approximately 2.4 at pH 6.5 to approximately 1.8 at pH 8.5. In the direct reduction of the fully oxidized enzyme (O --> R transition), the H+/COX ratio for proton release from COV increased from approximately 0.3 at pH 6.5 to approximately 1.6 at pH 8.5. Anaerobic oxidation by ferricyanide of the fully reduced oxidase, reconstituted in COV or in the soluble case, resulted in H+ release which exhibited, in both cases, an H+/COX ratio of 1.7-1.9 in the pH range 6.5-8.5. This H+ release associated with ferricyanide oxidation of the oxidase, in the absence of oxygen, originates evidently from deprotonation of acidic groups in the enzyme cooperatively linked to the redox state of the metal centers (redox Bohr protons). The additional H+ release (O2 versus ferricyanide oxidation) approaching 1 H+/COX at pH or = 8.5, this additional proton release takes place in the reductive phase of the catalytic cycle of the oxidase. The H+/COX ratio for proton release from COV in the overall catalytic cycle, oxidation by O2 of the fully reduced oxidase directly followed by re-reduction (R --> O --> R transition), exhibited a bell-shaped pH dependence approaching 4 at pH 7.2. A mechanism for the involvement in the proton pump of the oxidase of H+/e- cooperative coupling at the metal centers (redox Bohr effects) and protonmotive steps of reduction of O2 to H2O is presented.

  19. Evaluation of Biofuel Cells with Hemoglobin as Cathodic Electrocatalysts for Hydrogen Peroxide Reduction on Bare Indium-Tin-Oxide Electrodes

    Directory of Open Access Journals (Sweden)

    Yusuke Ayato

    2013-12-01

    Full Text Available A biofuel cell (BFC cathode has been developed based on direct electron transfer (DET of hemoglobin (Hb molecules with an indium-tin-oxide (ITO electrode and their electrocatalysis for reduction of hydrogen peroxide (H2O2. In this study, the ITO-coated glass plates or porous glasses were prepared by using a chemical vapor deposition (CVD method and examined the electrochemical characteristics of the formed ITO in pH 7.4 of phosphate buffered saline (PBS solutions containing and not containing Hb. In half-cell measurements, the reduction current of H2O2 due to the electrocatalytic activity of Hb increased with decreasing electrode potential from around 0.1 V versus Ag|AgCl|KCl(satd. in the PBS solution. The practical open-circuit voltage (OCV on BFCs utilizing H2O2 reduction at the Hb-ITO cathode with a hydrogen (H2 oxidation anode at a platinum (Pt electrode was expected to be at least 0.74 V from the theoretical H2 oxidation potential of −0.64 V versus Ag|AgCl|KCl(satd. in pH 7.4. The assembled single cell using the ITO-coated glass plate showed the OCV of 0.72 V and the maximum power density of 3.1 µW cm−2. The maximum power per single cell was recorded at 21.5 µW by using the ITO-coated porous glass.

  20. Oxidation-reduction potential and its influence on Cheddar cheese quality

    OpenAIRE

    Caldeo, Veronica

    2015-01-01

    Oxidation-reduction (redox) potential is a fundamental physicochemical parameter that affects the growth of microorganisms in dairy products and contributes to a balanced flavour development in cheese. Even though redox potential has an important impact on the quality of dairy products, it is not usually monitored in dairy industry. The aims of this thesis were to develop practical methods for measuring redox potential in cheese, to provide detailed information on changes in redox potential d...

  1. Energy conservation via electron bifurcating ferredoxin reduction and proton/Na(+) translocating ferredoxin oxidation.

    Science.gov (United States)

    Buckel, Wolfgang; Thauer, Rudolf K

    2013-02-01

    The review describes four flavin-containing cytoplasmatic multienzyme complexes from anaerobic bacteria and archaea that catalyze the reduction of the low potential ferredoxin by electron donors with higher potentials, such as NAD(P)H or H(2) at ≤ 100 kPa. These endergonic reactions are driven by concomitant oxidation of the same donor with higher potential acceptors such as crotonyl-CoA, NAD(+) or heterodisulfide (CoM-S-S-CoB). The process called flavin-based electron bifurcation (FBEB) can be regarded as a third mode of energy conservation in addition to substrate level phosphorylation (SLP) and electron transport phosphorylation (ETP). FBEB has been detected in the clostridial butyryl-CoA dehydrogenase/electron transferring flavoprotein complex (BcdA-EtfBC), the multisubunit [FeFe]hydrogenase from Thermotoga maritima (HydABC) and from acetogenic bacteria, the [NiFe]hydrogenase/heterodisulfide reductase (MvhADG-HdrABC) from methanogenic archaea, and the transhydrogenase (NfnAB) from many Gram positive and Gram negative bacteria and from anaerobic archaea. The Bcd/EtfBC complex that catalyzes electron bifurcation from NADH to the low potential ferredoxin and to the high potential crotonyl-CoA has already been studied in some detail. The bifurcating protein most likely is EtfBC, which in each subunit (βγ) contains one FAD. In analogy to the bifurcating complex III of the mitochondrial respiratory chain and with the help of the structure of the human ETF, we propose a conformational change by which γ-FADH(-) in EtfBC approaches β-FAD to enable the bifurcating one-electron transfer. The ferredoxin reduced in one of the four electron bifurcating reactions can regenerate H(2) or NADPH, reduce CO(2) in acetogenic bacteria and methanogenic archaea, or is converted to ΔμH(+)/Na(+) by the membrane-associated enzyme complexes Rnf and Ech, whereby NADH and H(2) are recycled, respectively. The mainly bacterial Rnf complexes couple ferredoxin oxidation by NAD(+) with

  2. Interim glycol flowsheet reduction/oxidation (redox) model for the Defense Waste Processing Facility (DWPF)

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Zamecnik, J. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Missimer, D. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-03-08

    Control of the REDuction/OXidation (REDOX) state of glasses containing high concentrations of transition metals, such as High Level Waste (HLW) glasses, is critical in order to eliminate processing difficulties caused by overly reduced or overly oxidized melts. Operation of a HLW melter at Fe+2/ΣFe ratios of between 0.09 and 0.33, a range which is not overly oxidizing or overly reducing, helps retain radionuclides in the melt, i.e. long-lived radioactive 99Tc species in the less volatile reduced Tc4+ state, 104Ru in the melt as reduced Ru+4 state as insoluble RuO2, and hazardous volatile Cr6+ in the less soluble and less volatile Cr+3 state in the glass. The melter REDOX control balances the oxidants and reductants from the feed and from processing additives such as antifoam. Currently, the Defense Waste Processing Facility (DWPF) is running a formic acid-nitric acid (FN) flowsheet where formic acid is the main reductant and nitric acid is the main oxidant. During decomposition formate and formic acid releases H2 gas which requires close control of the melter vapor space flammability. A switch to a nitric acid-glycolic acid (GN) flowsheet is desired as the glycolic acid flowsheet releases considerably less H2 gas upon decomposition. This would greatly simplify DWPF processing. Development of an EE term for glycolic acid in the GN flowsheet is documented in this study.

  3. Green Approach for the Effective Reduction of Graphene Oxide Using Salvadora persica L. Root (Miswak) Extract

    Science.gov (United States)

    Khan, Mujeeb; Al-Marri, Abdulhadi H.; Khan, Merajuddin; Shaik, Mohammed Rafi; Mohri, Nils; Adil, Syed Farooq; Kuniyil, Mufsir; Alkhathlan, Hamad Z.; Al-Warthan, Abdulrahman; Tremel, Wolfgang; Tahir, Muhammad Nawaz; Siddiqui, Mohammed Rafiq H.

    2015-07-01

    Recently, green reduction of graphene oxide (GRO) using various natural materials, including plant extracts, has drawn significant attention among the scientific community. These methods are sustainable, low cost, and are more environmentally friendly than other standard methods of reduction. Herein, we report a facile and eco-friendly method for the bioreduction of GRO using Salvadora persica L. ( S. persica L.) roots (miswak) extract as a bioreductant. The as-prepared highly reduced graphene oxide (SP-HRG) was characterized using powder X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron (XPS) spectroscopy, and transmission electron microscopy (TEM). Various results have confirmed that the biomolecules present in the root extract of miswak not only act as a bioreductant but also functionalize the surface of SP-HRG by acting as a capping ligand to stabilize it in water and other solvents. The dispersion quality of SP-HRG in deionized water was investigated in detail by preparing different samples of SP-HRG with increasing concentration of root extract. Furthermore, the dispersibility of SP-HRG was also compared with chemically reduced graphene oxide (CRG). The developed eco-friendly method for the reduction of GRO could provide a better substitute for a large-scale production of dispersant-free graphene and graphene-based materials for various applications in both technological and biological fields such as electronics, nanomedicine, and bionic materials.

  4. Nitrate reduction to nitrite, nitric oxide and ammonia by gut bacteria under physiological conditions.

    Science.gov (United States)

    Tiso, Mauro; Schechter, Alan N

    2015-01-01

    The biological nitrogen cycle involves step-wise reduction of nitrogen oxides to ammonium salts and oxidation of ammonia back to nitrites and nitrates by plants and bacteria. Neither process has been thought to have relevance to mammalian physiology; however in recent years the salivary bacterial reduction of nitrate to nitrite has been recognized as an important metabolic conversion in humans. Several enteric bacteria have also shown the ability of catalytic reduction of nitrate to ammonia via nitrite during dissimilatory respiration; however, the importance of this pathway in bacterial species colonizing the human intestine has been little studied. We measured nitrite, nitric oxide (NO) and ammonia formation in cultures of Escherichia coli, Lactobacillus and Bifidobacterium species grown at different sodium nitrate concentrations and oxygen levels. We found that the presence of 5 mM nitrate provided a growth benefit and induced both nitrite and ammonia generation in E.coli and L.plantarum bacteria grown at oxygen concentrations compatible with the content in the gastrointestinal tract. Nitrite and ammonia accumulated in the growth medium when at least 2.5 mM nitrate was present. Time-course curves suggest that nitrate is first converted to nitrite and subsequently to ammonia. Strains of L.rhamnosus, L.acidophilus and B.longum infantis grown with nitrate produced minor changes in nitrite or ammonia levels in the cultures. However, when supplied with exogenous nitrite, NO gas was readily produced independently of added nitrate. Bacterial production of lactic acid causes medium acidification that in turn generates NO by non-enzymatic nitrite reduction. In contrast, nitrite was converted to NO by E.coli cultures even at neutral pH. We suggest that the bacterial nitrate reduction to ammonia, as well as the related NO formation in the gut, could be an important aspect of the overall mammalian nitrate/nitrite/NO metabolism and is yet another way in which the microbiome

  5. Reduction of antibiotic resistance genes in municipal wastewater effluent by advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yingying; Zhuang, Yao; Geng, Jinju, E-mail: jjgeng@nju.edu.cn; Ren, Hongqiang; Xu, Ke; Ding, Lili

    2016-04-15

    This study investigated the reduction of antibiotic resistance genes (ARGs), intI1 and 16S rRNA genes, by advanced oxidation processes (AOPs), namely Fenton oxidation (Fe{sup 2+}/H{sub 2}O{sub 2}) and UV/H{sub 2}O{sub 2} process. The ARGs include sul1, tetX, and tetG from municipal wastewater effluent. The results indicated that the Fenton oxidation and UV/H{sub 2}O{sub 2} process could reduce selected ARGs effectively. Oxidation by the Fenton process was slightly better than that of the UV/H{sub 2}O{sub 2} method. Particularly, for the Fenton oxidation, under the optimal condition wherein Fe{sup 2+}/H{sub 2}O{sub 2} had a molar ratio of 0.1 and a H{sub 2}O{sub 2} concentration of 0.01 mol L{sup −1} with a pH of 3.0 and reaction time of 2 h, 2.58–3.79 logs of target genes were removed. Under the initial effluent pH condition (pH = 7.0), the removal was 2.26–3.35 logs. For the UV/H{sub 2}O{sub 2} process, when the pH was 3.5 with a H{sub 2}O{sub 2} concentration of 0.01 mol L{sup −1} accompanied by 30 min of UV irradiation, all ARGs could achieve a reduction of 2.8–3.5 logs, and 1.55–2.32 logs at a pH of 7.0. The Fenton oxidation and UV/H{sub 2}O{sub 2} process followed the first-order reaction kinetic model. The removal of target genes was affected by many parameters, including initial Fe{sup 2+}/H{sub 2}O{sub 2} molar ratios, H{sub 2}O{sub 2} concentration, solution pH, and reaction time. Among these factors, reagent concentrations and pH values are the most important factors during AOPs. - Highlights: • AOPs including Fenton oxidation and UV/H{sub 2}O{sub 2} process could reduce ARGs effectively. • Fenton oxidation is slightly more effective than UV/H{sub 2}O{sub 2} process in ARG reduction. • Removal of ARGs by AOPs follows the first-order reaction kinetic model. • Selected ARGs and 16S rRNA genes exhibit similar change trends during AOPs.

  6. Efficient Reduction of Antibacterial Activity and Cytotoxicity of Fluoroquinolones by Fungal-Mediated N-Oxidation.

    Science.gov (United States)

    Rusch, Marina; Spielmeyer, Astrid; Meißner, Jessica; Kietzmann, Manfred; Zorn, Holger; Hamscher, Gerd

    2017-04-19

    Extensive usage of fluoroquinolone antibiotics in livestock results in their occurrence in manure and subsequently in the environment. Fluoroquinolone residues may promote bacterial resistance and are toxic to plants and aquatic organisms. Moreover, fluoroquinolones may enter the food chain through plant uptake, if manure is applied as fertilizer. Thus, the presence of fluoroquinolones in the environment may pose a threat to human and ecological health. In this study, the biotransformation of enrofloxacin, marbofloxacin, and difloxacin by the fungus X. longipes (Xylaria) was investigated. The main metabolites were unequivocally identified as the respective N-oxides by mass spectrometry and nuclear magnetic resonance spectroscopy. Fungal-mediated N-oxidation of fluoroquinolones led to a 77-90% reduction of the initial antibacterial activity. In contrast to their respective parent compounds, N-oxides showed low cytotoxic potential and had a reduced impact on cell proliferation. Thus, biotransformation by X. longipes may represent an effective method for inactivating fluoroquinolones.

  7. Hydrogenation of Styrene Oxide to 2-Phenylethanol over Nanocrystalline Ni Prepared by Ethylene Glycol Reduction Method

    Directory of Open Access Journals (Sweden)

    Sunil K. Kanojiya

    2014-01-01

    Full Text Available Nanocrystalline nickel prepared by glycol reduction method and characterized by XRD and magnetic measurements has been used as a catalyst for hydrogenation of styrene oxide to 2-phenylethanol. Effect of process variables such as particle size of the catalyst, temperature, and pressure have been optimized to achieve a maximum conversion of 98% of styrene oxide with 99% selectivity towards 2-phenylethanol. The structure of the transition state has been computed employing density functional theory and using Gaussian 09 suite. The enthalpy of reaction (ΔH and activation energy (Ea are calculated to be 85.3 kcal·mol−1 and 123.03 kcal·mol−1, respectively. A tentative mechanism for the reaction is proposed according to which atomized hydrogen and styrene oxide react together over the catalyst surface to produce 2-phenylethanol.

  8. Electro-catalytic effect of manganese oxide on oxygen reduction at teflonbonded carbon electrode

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Oxygen reduction(OR)on Teflon-bonded carbon electrodes with manganese oxide as catalyst in 6 mol/L KOH solution was investigated using AC impedance spectroscopy combined with other techniques. For OR at this electrode, the Tafel slope is-0.084V/dec and the apparent exchange current density is (1.02-3.0)×10-7 A/cm2. In the presence of manganese oxide on carbon electrode,the couple Mn3+/Mn4+ reacts with the O2 adsorbed on carbon sites forming O2- radicals and acceletes the dismutation of O2-, which contributes to the catalytic effect of manganese oxide for OR reaction.

  9. One-pot green synthesis of silver/iron oxide composite nanoparticles for 4-nitrophenol reduction.

    Science.gov (United States)

    Chiou, Jau-Rung; Lai, Bo-Hung; Hsu, Kai-Chih; Chen, Dong-Hwang

    2013-03-15

    Silver/iron oxide composite nanoparticles have been synthesized successfully via a facile one-pot green route by the use of l-arginine, which created an aqueous solution of about pH 10 and acted as a reducing agent for the successive formation of iron oxide and Ag nanoparticles. The product was characterized to be silver-coated iron oxide and iron oxide hydroxide composite nanoparticles with a mean diameter of about 13.8 ± 3.0 nm and 8.53% of Ag in weight. It exhibited good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride. The reduction reaction followed the pseudo-first-order kinetics. The corresponding rate constants increased with the increases of temperature and catalyst amount but decreased with the increase of initial 4-NP concentration, revealing an activation energy of 28.2 kJ/mol and a diffusion controlled mechanism. In addition, this product had quite good stability. No significant activity loss was observed after reuse for 5 cycles. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Reduction Of Cod And Bod By Oxidation: A Cetp Case Study

    Directory of Open Access Journals (Sweden)

    Prashant K. Lalwani, Malu D. Devadasan

    2013-05-01

    Full Text Available The present study is focused on a Common Effluent Treatment Plant (CETP located at Umaraya, District Baroda. Waste water from about thirty five small and medium scale industries majorly comprising of chemical manufacturing and pharmaceutical industries are treated in this CETP. The incoming wastewater was collected and segregated into three groups as per their BOD/COD ratio. They were then oxidized independently by two oxidants Fenton’s reagent (Fe2+/H2O2 and Sodium Hypochlorite (NaOCl and reduction in COD and BOD were observed at different chlorine, H2O2, FeSO4 doses, different pH values and contact time for determining the optimum values. COD and BOD values at optimized conditions for the two oxidants were compared and observed that maximum reduction of 64.35% and 68.57% respectively was achieved by Fenton’s reagent. The results clearly indicate that conventional system should be replaced by advanced oxidation process and Fenton’s reagent is a suitable choice.

  11. Regulation of Ca2+ release from mitochondria by the oxidation-reduction state of pyridine nucleotides.

    Science.gov (United States)

    Lehninger, A L; Vercesi, A; Bababunmi, E A

    1978-04-01

    Mitochondria from normal rat liver and heart, and also Ehrlich tumor cells, respiring on succinate as energy source in the presence of rotenone (to prevent net electron flow to oxygen from the endogenous pyridine nucleotides), rapidly take up Ca(2+) and retain it so long as the pyridine nucleotides are kept in the reduced state. When acetoacetate is added to bring the pyridine nucleotides into a more oxidized state, Ca(2+) is released to the medium. A subsequent addition of a reductant of the pyridine nucleotides such as beta-hydroxybutyrate, glutamate, or isocitrate causes reuptake of the released Ca(2+). Successive cycles of Ca(2+) release and uptake can be induced by shifting the redox state of the pyridine nucleotides to more oxidized and more reduced states, respectively. Similar observations were made when succinate oxidation was replaced as energy source by ascorbate oxidation or by the hydrolysis of ATP. These and other observations form the basis of a hypothesis for feedback regulation of Ca(2+)-dependent substrate- or energy-mobilizing enzymatic reactions by the uptake or release of mitochondrial Ca(2+), mediated by the cytosolic phosphate potential and the ATP-dependent reduction of mitochondrial pyridine nucleotides by reversal of electron transport.

  12. Reduction of antibiotic resistance genes in municipal wastewater effluent by advanced oxidation processes.

    Science.gov (United States)

    Zhang, Yingying; Zhuang, Yao; Geng, Jinju; Ren, Hongqiang; Xu, Ke; Ding, Lili

    2016-04-15

    This study investigated the reduction of antibiotic resistance genes (ARGs), intI1 and 16S rRNA genes, by advanced oxidation processes (AOPs), namely Fenton oxidation (Fe(2+)/H2O2) and UV/H2O2 process. The ARGs include sul1, tetX, and tetG from municipal wastewater effluent. The results indicated that the Fenton oxidation and UV/H2O2 process could reduce selected ARGs effectively. Oxidation by the Fenton process was slightly better than that of the UV/H2O2 method. Particularly, for the Fenton oxidation, under the optimal condition wherein Fe(2+)/H2O2 had a molar ratio of 0.1 and a H2O2 concentration of 0.01molL(-1) with a pH of 3.0 and reaction time of 2h, 2.58-3.79 logs of target genes were removed. Under the initial effluent pH condition (pH=7.0), the removal was 2.26-3.35 logs. For the UV/H2O2 process, when the pH was 3.5 with a H2O2 concentration of 0.01molL(-1) accompanied by 30min of UV irradiation, all ARGs could achieve a reduction of 2.8-3.5 logs, and 1.55-2.32 logs at a pH of 7.0. The Fenton oxidation and UV/H2O2 process followed the first-order reaction kinetic model. The removal of target genes was affected by many parameters, including initial Fe(2+)/H2O2 molar ratios, H2O2 concentration, solution pH, and reaction time. Among these factors, reagent concentrations and pH values are the most important factors during AOPs.

  13. Electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices

    Science.gov (United States)

    He, Zhen

    The focus of this dissertation is the electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices. The electrochemical reduction of metal oxides to metals has been studied for decades as an alternative to pyrometallurgical processes for the metallurgy industry. However, the previous work was conducted on bulk polycrystalline metal oxides. Paper I in this dissertation shows that epitaxial face-centered cubic magnetite (Fe3O4 ) thin films can be electrochemically reduced to epitaxial body-centered cubic iron (Fe) thin films in aqueous solution on single-crystalline Au substrates at room temperature. This technique opens new possibilities to produce special epitaxial metal/metal oxide heterojunctions and a wide range of epitaxial metallic alloy films from the corresponding mixed metal oxides. Electrodeposition, like biomineralization, is a soft solution processing method which can produce functional materials with special properties onto conducting or semiconducting solid surfaces. Paper II in this dissertation presents the electrodeposition of cobalt-substituted magnetite (CoxFe3-xO4, 0 of cobalt-substituted magnetite (CoxFe3-xO4, 0oxide (Co3O4) thin films on stainless steel and Au single-crystalline substrates. The crystalline Co3O4 thin films exhibit high catalytic activity towards the oxygen evolution reaction in an alkaline solution. A possible application of the electrodeposited Co 3O4 is the fabrication of highly active and low-cost photoanodes for photoelectrochemical water-splitting cells.

  14. Environmental Factors Affecting Chromium-Manganese Oxidation-Reduction Reactions in Soil

    Institute of Scientific and Technical Information of China (English)

    D.O.P.TREBIEN; L.BORTOLON; M.J.TEDESCO; C.A.BISSANI; F.A.O.CAMARGO

    2011-01-01

    Disposal of chromium (Cr) hexavalent form, Cr(Ⅵ), in soils as additions in organic fertilizers, liming materials or plant nutrient sources can be dangerous since Cr(Ⅵ) can be highly toxic to plants, animals, and humans. In order to explore soil conditions that lead to Cr(Ⅵ) generation, this study were performed using a Paleudult (Dystic Nitosol) from a region that has a high concentration of tannery operations in the Rio Grande do Sul State, southern Brazil. Three laboratory incubation experiments were carried out to examine the influences of soil moisture content and concentration of cobalt and organic matter additions on soil Cr(Ⅵ) formation and release and manganese (Mn) oxide reduction with a salt of chromium chloride (CrCl3) and tannery sludge as inorganic and organic sources of Cr(Ⅲ), respectively. The amount of Cr(Ⅲ) oxidation depended on the concentration of easily reducible Mn oxides and the oxidation was more intense at the soil water contents in which Mn(Ⅲ/Ⅳ) oxides were more stable. Soluble organic compounds in soil decreased Cr(Ⅵ) formation due to Cr(Ⅲ) complexation. This mechanism also resulted in the decrease in the oxidation of Cr(Ⅲ) due to the tannery sludge additions. Chromium(Ⅲ) oxidation to Cr(Ⅵ) at the solid/solution interface involved the following mechanisms:the formation of a precursor complex on manganese (Mn) oxide surfaces, followed by electron transfer from Cr(Ⅲ) to Mn(Ⅲ or Ⅳ),the formation of a successor complex with Mn(Ⅱ) and Cr(Ⅵ), and the breakdown of the successor complex and release of Mn(Ⅱ) and Cr(Ⅵ) into the soil solution.

  15. Direct oxidation of methane to oxygenates over heteropolyanions

    Institute of Scientific and Technical Information of China (English)

    Ouarda Benlounes; Sadia Mansouri; Chérifa Rabia; Smain Hocine

    2008-01-01

    Partia]oxidation of methane to formaldehyde and methanol was studied at atmospheric pressure in the ternlperature range of 700-750℃ using heteropolycompound catalysts(NH4)6HSiMo11 FeO40,(NH4)4PMo11 FeO39,and H4PMo11VO40,which were prepared and characterized by various analysis techniques such as infrared,visible UV,XRD and DTA.O2 or N2O was used as the oxidizing agent.and the principal products of the reaction were CH3OH,CH2O,CO,CO2,and water.The conversion and the selectivity of products depend strongly on the reaction temperature,the nature of oxidizing agent,and the composition of catalyst.

  16. Red wine-dependent reduction of nitrite to nitric oxide in the stomach.

    Science.gov (United States)

    Gago, Bruno; Lundberg, Jon O; Barbosa, Rui M; Laranjinha, João

    2007-11-01

    Nitrite may be a source for nitric oxide (*NO), particularly in highly acidic environments, such as the stomach. Diet products contribute also with reductants that dramatically increase the production of *NO from nitrite. Red wine has been attributed health promoting properties largely on basis of the reductive antioxidant properties of its polyphenolic fraction. We show in vitro that wine, wine anthocyanin fraction and wine catechol (caffeic acid) dose- and pH-dependently promote the formation of *NO when mixed with nitrite, as measured electrochemically. The production of *NO promoted by wine from nitrite was substantiated in vivo in healthy volunteers by measuring *NO in the air expelled from the stomach, following consumption of wine, as measured by chemiluminescence. Mechanistically, the reaction involves the univalent reduction of nitrite, as suggested by the formation of *NO and by the appearance of EPR spectra assigned to wine phenolic radicals. Ascorbic and caffeic acids cooperate in the reduction of nitrite to *NO. Moreover, reduction of nitrite is critically dependent on the phenolic structure and nitro-derivatives of phenols are also formed, as suggested by caffeic acid UV spectral modifications. The reduction of nitrite may reveal previously unrecognized physiologic effects of red wine in connection with *NO bioactivity.

  17. Reduction of excess sludge production in sequencing batch reactor through incorporation of chlorine dioxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guanghua [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China); Guangzhou municipal engineering design and research institute, Guangzhou, 510060 (China); Sui Jun [Guangzhou municipal engineering design and research institute, Guangzhou, 510060 (China); Shen Huishan; Liang Shukun [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China); He Xiangming; Zhang Minju; Xie Yizhong; Li Lingyun [Nanhai Limited Liability Development Company, Foshan, 528200 (China); Hu Yongyou, E-mail: ppyyhu@scut.edu.cn [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China) and State Key Lab of Pulp and Paper Engineering, College of Light Industry and Food Science, South China University of Technology; Guangzhou, 510640 (China)

    2011-08-15

    In this study, chlorine dioxide (ClO{sub 2}) instead of chlorine (Cl{sub 2}) was proposed to minimize the formation of chlorine-based by-products and was incorporated into a sequencing batch reactor (SBR) for excess sludge reduction. The results showed that the sludge disintegrability of ClO{sub 2} was excellent. The waste activated sludge at an initial concentration of 15 g MLSS/L was rapidly reduced by 36% using ClO{sub 2} doses of 10 mg ClO{sub 2}/g dry sludge which was much lower than that obtained using Cl{sub 2} based on similar sludge reduction efficiency. Maximum sludge disintegration was achieved at 10 mg ClO{sub 2}/g dry sludge for 40 min. ClO{sub 2} oxidation can be successfully incorporated into a SBR for excess sludge reduction without significantly harming the bioreactor performance. The incorporation of ClO{sub 2} oxidation resulted in a 58% reduction in excess sludge production, and the quality of the effluent was not significantly affected.

  18. Effect of copper oxide electrocatalyst on CO2 reduction using Co3O4 as anode

    Directory of Open Access Journals (Sweden)

    V.S.K. Yadav

    2016-09-01

    Full Text Available The reduction of carbon dioxide (CO2 to products electrochemically (RCPE in 0.5 M NaHCO3 and Na2CO3 liquid phase electrolyte solutions was investigated. Cobalt oxide (Co3O4 as anode and cuprous oxide (Cu2O as the cathode were considered, respectively. The impacts of applied potential with time of reaction during reduction of CO2 to products were studied. The anode and cathode were prepared by depositing electrocatalysts on the graphite plate. Ultra-fast liquid chromatography (UFLC was used to analyze the products obtained from the reduction of CO2. The feasible way of reduction by applying voltages with current densities was clearly correlated. The results illustrate the capability of electrocatalyst successfully to remove atmospheric CO2 in the form of valuable chemicals. Maximum Faradaic efficiency of ethanol was 98.1% at 2 V and for formic acid (36.6% at 1.5 V was observed in NaHCO3. On the other hand, in Na2CO3 electrolyte solution maximum efficiency for ethanol was 55.21% at 1.5 V and 25.1% for formic acid at 2 V. In both electrolytes other end products like methanol, propanol, formaldehyde and acetic acid were formed at various applied voltage and output current densities.

  19. Reduced graphene oxide as photocatalyst for CO2 reduction reaction(Conference Presentation)

    Science.gov (United States)

    Chang, Yu-Chung

    2016-10-01

    Photocatalytic conversion of carbon dioxide (CO2) to hydrocarbons such as methanol makes possible simultaneous solar energy harvesting and CO2 reduction. Our previous work is using graphene oxide (GO) as a promising photocatalyst for photocatalytic conversion of CO2 to methanol[1].When using graphene oxide as photocatalyst, the photocatalytic efficiency is 4-flod higher than TiO2 powder. GO has a lot of defects on the surface and those defects make sp2 carbon structure become sp3 carbon structure. The carbon structure change cause the GO has large energy gap about 2.7 eV to 3.2 eV. In order to remove the defect and reduce the energy gap of GO, Zhao et al. try to annealing GO powder in the nitrogen atmosphere at 900oC, the GO structure can be reduced to near graphene structure[2]. Zhu et al. do some low temperature annealing, it can control the structure and energy bandgap of GO by control annealing temperature. If the annealing temperature increase the bandgap of GO will be reduce[3]. So, we can using this annealing process to reduce the bandgap of the GO. In the varying temperature thermal reduction process, as the temperature increases from 130oC to 170oC, the functional groups of the graphene oxide will be reduced and band gap of graphene oxide will be narrowed at same time. The characteristic of thermal reduced graphene oxide were analyzed by SEM, XRD and Raman measurements. The band position was determined by UV/Vis. The reduction of functional groups correlates to red shift in light absorption and eventual quenching in the PL signal of RGOs. Combining hydrophobicity, light harvesting and PL quench, we get the highest yield of RGO150 (0.31 μmole g-1 -cat hr-1) is 1.7-fold higher than that of GO (0.18μmole g-1 -cat hr-1). This work investigates a modified method for using a thermal reduction process to reduce the energy gap of graphene oxide.

  20. Observations of Oxygen Ion Behavior in the Lithium-Based Electrolytic Reduction of Uranium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Steven D. Herrmann; Shelly X. Li; Brenda E. Serrano-Rodriguez

    2009-09-01

    Parametric studies were performed on a lithium-based electrolytic reduction process at bench-scale to investigate the behavior of oxygen ions in the reduction of uranium oxide for various electrochemical cell configurations. Specifically, a series of eight electrolytic reduction runs was performed in a common salt bath of LiCl – 1 wt% Li2O. The variable parameters included fuel basket containment material (i.e., stainless steel wire mesh and sintered stainless steel) and applied electrical charge (i.e., 75 – 150% of the theoretical charge for complete reduction of uranium oxide in a basket to uranium metal). Samples of the molten salt electrolyte were taken at regular intervals throughout each run and analyzed to produce a time plot of Li2O concentrations in the bulk salt over the course of the runs. Following each run, the fuel basket was sectioned and the fuel was removed. Samples of the fuel were analyzed for the extent of uranium oxide reduction to metal and for the concentration of salt constituents, i.e., LiCl and Li2O. Extents of uranium oxide reduction ranged from 43 – 70% in stainless steel wire mesh baskets and 8 – 33 % in sintered stainless steel baskets. The concentrations of Li2O in the salt phase of the fuel product from the stainless steel wire mesh baskets ranged from 6.2 – 9.2 wt%, while those for the sintered stainless steel baskets ranged from 26 – 46 wt%. Another series of tests was performed to investigate the dissolution of Li2O in LiCl at 650 °C across various cathode containment materials (i.e., stainless steel wire mesh, sintered stainless steel and porous magnesia) and configurations (i.e., stationary and rotating cylindrical baskets). Dissolution of identical loadings of Li2O particulate reached equilibrium within one hour for stationary stainless steel wire mesh baskets, while the same took several hours for sintered stainless steel and porous magnesia baskets. Rotation of an annular cylindrical basket of stainless steel

  1. Oxidation of diesel-generated volatile organic compounds in the selective catalytic reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Koebel, M.; Elsener, M. [Paul Scherrer Inst., Villigen (Switzerland). Combustion Research

    1998-10-01

    The main part of the VOCs (volatile organic compounds) contained in diesel exhaust ({approx}80%) is oxidized to CO and CO{sub 2} over an SCR (selective catalytic reduction) catalyst. CO is the major product of this oxidation, representing about 50--70% of the formed products (CO + CO{sub 2}). This preferential formation of CO leads to a pronounced increase of CO emissions when an SCR process is added to a diesel engine. A small fraction of the VOCs is selectively oxidized to carboxylic acids over the SCR catalyst. This selectivity is due to the acidic properties of the catalyst causing the preferential desorption at the oxidation state of the acid. The main products of these oxidation reactions are the lower monocarboxylic acids and some dicarboxylic acids forming stable anhydrides, especially maleic and phthalic acid. The highest emissions of these acids are found at low temperatures; they decrease at higher temperatures. Formic acid is preferentially decomposed into carbon monoxide and water. It must therefore be assumed that the strong increase of CO mentioned above is due to a mechanism involving the thermal decomposition of formic acid formed from various primary VOCs.

  2. Oxidation and reduction behaviors of a prototypic MgO-PuO2-x inert matrix fuel

    Science.gov (United States)

    Miwa, Shuhei; Osaka, Masahiko

    2017-04-01

    Oxidation and reduction behaviors of prototypic MgO-based inert matrix fuels (IMFs) containing PuO2-x were experimentally investigated by means of thermogravimetry. The oxidation and reduction kinetics of the MgO-PuO2-x specimen were determined. The oxidation and reduction rates of the MgO-PuO2-x were found to be low compared with those of PuO2-x. It is note that the changes in O/Pu ratios of MgO-PuO2-x from stoichiometry were smaller than those of PuO2-x at high oxygen partial pressure.

  3. Self-assembled platinum nanoflowers on polydopamine-coated reduced graphene oxide for methanol oxidation and oxygen reduction reactions.

    Science.gov (United States)

    Yu, Xueqing; Wang, Huan; Guo, Liping; Wang, Liang

    2014-11-01

    The morphology- and size-controlled synthesis of branched Pt nanostructures on graphene is highly favorable for enhancing the electrocatalytic activity and stability of Pt. Herein, a facile approach is developed for the efficient synthesis of well-dispersed Pt nanoflowers (PtNFs) on the surface of polydopamine (PDA)-modified reduced graphene oxide (PDRGO), denoted as PtNFs/PDRGO, in high yield. The synthesis was performed by a simple heating treatment of an aqueous solution that contained K2PtCl4 and PDA-modified graphene oxide (GO) without the need for any additional reducing agent, seed, surfactant, or organic solvent. The coated PDA serves not only as a reducing agent, but also as cross-linker to anchor and stabilize PtNFs on the PDRGO support. The as-prepared PtNFs/PDRGO hybrid, with spatially and locally separated PtNFs on PDRGO, exhibits superior electrocatalytic activity and stability toward both methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in alkaline solutions.

  4. Improvement of Sodium Leaching Ratio of Ferric Bauxite Sinter after Direct Reduction

    Directory of Open Access Journals (Sweden)

    Wentao Hu

    2017-01-01

    Full Text Available The sodium leaching ratio (ηN of ferric bauxite direct reduction process is much lower than that of ordinary bauxite; thus, the former consumes more sodium than the latter. ηN can be promoted by increasing the dosage of sodium or restricted by increasing the heating temperature and time. However, the restriction effect of heating temperature is 16.67 times larger than that of heating time, and the restriction effect decreases 47.03 times faster when heating temperature increases than that process of heating time. These imply that ηN improves with the increasing sodium carbonate dosage and the decreasing heating temperature.

  5. Local direct and indirect reduction of electrografted aryldiazonium/gold surfaces for polymer brushes patterning

    Energy Technology Data Exchange (ETDEWEB)

    Hauquier, Fanny; Matrab, Tarik; Kanoufi, Frederic [Laboratoire Environnement et Chimie Analytique, CNRS UMR7121, ESPCI, 10 rue Vauquelin, 75231 Paris Cedex 05 (France); Combellas, Catherine [Laboratoire Environnement et Chimie Analytique, CNRS UMR7121, ESPCI, 10 rue Vauquelin, 75231 Paris Cedex 05 (France)], E-mail: Catherine.Combellas@espci.fr

    2009-09-01

    The patterning of conductive substrates by polymer brushes may be achieved by using successively scanning electrochemical microscopy (SECM) and atom transfer radical polymerization (ATRP). After the surface functionalization by a brominated aryldiazonium initiator, SECM allows the local reduction at the micrometer scale of the initiator grafted layer. Different channels sizes involved in charge transport within the initiator layers are evidenced by combining SECM, CV and observation of the aryl-grafted layer transformation. ATRP is performed on the SECM patterned substrate. Inside the pattern, the lower density of initiator decreases the polymer thickness. The pattern resolution is enhanced when the direct mode of the SECM is used instead of the mediated indirect mode.

  6. Smelting in cupola furnace for recarburization of direct reduction iron (DRI

    Directory of Open Access Journals (Sweden)

    Enríquez, José L.

    2015-12-01

    Full Text Available Herein the synthesis of iron-carbon saturated alloys (foundries melting in cupola furnaces from direct reduction iron is described. The fundamentals are reviewed and combinations undertaken are discussed along with their results, including conclusions and recommendations for follow up.Se describe la síntesis de aleaciones saturadas hierro-carbono (fundiciones en hornos de cubilote a partir de hierro de reducción directa. Se revisan sus fundamentos, operaciones realizadas, resultados y conclusiones. Finalmente se ofrecen recomendaciones para su implantación industrial.

  7. IMPACTS OF ANTIFOAM ADDITIONS AND ARGON BUBBLING ON DEFENSE WASTE PROCESSING FACILITY REDUCTION/OXIDATION

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C.; Johnson, F.

    2012-06-05

    During melting of HLW glass, the REDOX of the melt pool cannot be measured. Therefore, the Fe{sup +2}/{Sigma}Fe ratio in the glass poured from the melter must be related to melter feed organic and oxidant concentrations to ensure production of a high quality glass without impacting production rate (e.g., foaming) or melter life (e.g., metal formation and accumulation). A production facility such as the Defense Waste Processing Facility (DWPF) cannot wait until the melt or waste glass has been made to assess its acceptability, since by then no further changes to the glass composition and acceptability are possible. therefore, the acceptability decision is made on the upstream process, rather than on the downstream melt or glass product. That is, it is based on 'feed foward' statistical process control (SPC) rather than statistical quality control (SQC). In SPC, the feed composition to the melter is controlled prior to vitrification. Use of the DWPF REDOX model has controlled the balanjce of feed reductants and oxidants in the Sludge Receipt and Adjustment Tank (SRAT). Once the alkali/alkaline earth salts (both reduced and oxidized) are formed during reflux in the SRAT, the REDOX can only change if (1) additional reductants or oxidants are added to the SRAT, the Slurry Mix Evaporator (SME), or the Melter Feed Tank (MFT) or (2) if the melt pool is bubble dwith an oxidizing gas or sparging gas that imposes a different REDOX target than the chemical balance set during reflux in the SRAT.

  8. Effect of gas composition on the kinetics of iron oxide reduction in a hydrogen production process

    Energy Technology Data Exchange (ETDEWEB)

    Piotrowski, Krzysztof; Lorethova, Hana; Stonawski, Lubor; Wiltowski, Tomasz [Coal Research Center, Southern Illinois University Carbondale, Carbondale, IL (United States); Mondal, Kanchan; Szymanski, Tomasz [Department of Mechanical Engineering and Energy Processes, Carbondale, IL (United States)

    2005-12-01

    Fe{sub 2}O{sub 3} is a suitable oxygen transfer agent for converting CO present in syngas to CO{sub 2} for its eventual separation from H{sub 2}. However, H{sub 2} also reacts with iron oxide to form H{sub 2}O. In order to evaluate the reactions for hydrogen enrichment, investigations into Fe{sub 2}O{sub 3} to FeO reduction kinetics in the presence of syngas constituents were conducted. The reaction kinetic parameters were estimated based on the thermogravimetric data. Hancock and Sharp method of comparing the kinetics of isothermal solid-state reactions, based on Johnson-Mehl-Avrami-Erofe'ev equation describing nucleation and growth processes, was applied. The experimental results indicate that the reduction is initially a surface-controlled process, but once a thin layer of lower iron oxides (magnetite, wusite) is formed on the surface, the mechanism shifts to diffusion control. It was concluded that this initial stage of the reaction process could be interpreted as a both phase-boundary-controlled reaction and the two-dimensional nucleation and growth (transformation of the crystallographic lattices of higher oxide to lattices of lower oxide) at the gas/iron oxide interface. Comparison of the reaction courses for both the reducing agents (H{sub 2}, CO) independently and for their mixture was performed. It was found, that the reaction rate increases with, both, temperature and the hydrogen content in inlet gas. The activation energy values were estimated and compared. (author)

  9. Nitric-glycolic flowsheet reduction/oxidation (redox) model for the defense waste processing facility (DWPF)

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Edwards, T. B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Trivelpiece, C. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Ramsey, W. G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-06-14

    Control of the REDuction/OXidation (REDOX) state of glasses containing high concentrations of transition metals, such as High Level Waste (HLW) glasses, is critical in order to eliminate processing difficulties caused by overly reduced or overly oxidized melts. Operation of a HLW melter at Fe+2/ΣFe ratios of between 0.09 and 0.33, retains radionuclides in the melt and thus the final glass. Specifically, long-lived radioactive 99Tc species are less volatile in the reduced Tc4+ state as TcO2 than as NaTcO4 or Tc2O7, and ruthenium radionuclides in the reduced Ru4+ state are insoluble RuO2 in the melt which are not as volatile as NaRuO4 where the Ru is in the +7 oxidation state. Similarly, hazardous volatile Cr6+ occurs in oxidized melt pools as Na2CrO4 or Na2Cr2O7, while the Cr+3 state is less volatile and remains in the melt as NaCrO2 or precipitates as chrome rich spinels. The melter REDOX control balances the oxidants and reductants from the feed and from processing additives such as antifoam.

  10. Direct k-space mapping of the electronic structure in an oxide-oxide interface.

    Science.gov (United States)

    Berner, G; Sing, M; Fujiwara, H; Yasui, A; Saitoh, Y; Yamasaki, A; Nishitani, Y; Sekiyama, A; Pavlenko, N; Kopp, T; Richter, C; Mannhart, J; Suga, S; Claessen, R

    2013-06-14

    The interface between LaAlO(3) and SrTiO(3) hosts a two-dimensional electron system of itinerant carriers, although both oxides are band insulators. Interface ferromagnetism coexisting with superconductivity has been found and attributed to local moments. Experimentally, it has been established that Ti 3d electrons are confined to the interface. Using soft x-ray angle-resolved resonant photoelectron spectroscopy we have directly mapped the interface states in k space. Our data demonstrate a charge dichotomy. A mobile fraction contributes to Fermi surface sheets, whereas a localized portion at higher binding energies is tentatively attributed to electrons trapped by O vacancies in the SrTiO(3). While photovoltage effects in the polar LaAlO(3) layers cannot be excluded, the apparent absence of surface-related Fermi surface sheets could also be fully reconciled in a recently proposed electronic reconstruction picture where the built-in potential in the LaAlO(3) is compensated by surface O vacancies serving also as a charge reservoir.

  11. Immunological detection of enzymes for sulfate reduction in anaerobic methane-oxidizing consortia.

    Science.gov (United States)

    Milucka, Jana; Widdel, Friedrich; Shima, Seigo

    2013-05-01

    Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SR) at marine gas seeps is performed by archaeal-bacterial consortia that have so far not been cultivated in axenic binary or pure cultures. Knowledge about possible biochemical reactions in AOM consortia is based on metagenomic retrieval of genes related to those in archaeal methanogenesis and bacterial sulfate reduction, and identification of a few catabolic enzymes in protein extracts. Whereas the possible enzyme for methane activation (a variant of methyl-coenzyme M reductase, Mcr) was shown to be harboured by the archaea, enzymes for sulfate activation and reduction have not been localized so far. We adopted a novel approach of fluorescent immunolabelling on semi-thin (0.3-0.5 μm) cryosections to localize two enzymes of the SR pathway, adenylyl : sulfate transferase (Sat; ATP sulfurylase) and dissimilatory sulfite reductase (Dsr) in microbial consortia from Black Sea methane seeps. Both Sat and Dsr were exclusively found in an abundant microbial morphotype (c. 50% of all cells), which was tentatively identified as Desulfosarcina/Desulfococcus-related bacteria. These results show that ANME-2 archaea in the Black Sea AOM consortia did not express bacterial enzymes of the canonical sulfate reduction pathway and thus, in contrast to previous suggestions, most likely cannot perform canonical sulfate reduction. Moreover, our results show that fluorescent immunolabelling on semi-thin cryosections which to our knowledge has been so far only applied on cell tissues, is a powerful tool for intracellular protein detection in natural microbial associations.

  12. Effect of reduction time on third order optical nonlinearity of reduced graphene oxide

    Science.gov (United States)

    Sreeja, V. G.; Vinitha, G.; Reshmi, R.; Anila, E. I.; Jayaraj, M. K.

    2017-04-01

    We report the influence of reduction time on structural, linear and nonlinear optical properties of reduced graphene oxide (rGO) thin films synthesized by spin coating method. We observed that the structural, linear and nonlinear optical properties can be tuned with reduction time in GO is due to the increased structural ordering because of the restoration of sp2 carbon atoms with the time of reduction. The nonlinear absorption studies by open aperture Z-scan technique exhibited a saturable absorption. The nonlinear refraction studies showed the self de focusing nature of rGO by closed aperture Z scan technique. The nonlinear absorption coefficient and saturation intensity varies with the time for reduction of GO which is attributed to the depletion of valence band and the conduction band filling effect. Our results emphasize duration for reduction of GO dependent optical nonlinearity of rGO thin films to a great extent and explore its applications Q switched mode locking laser systems for generating ultra short laser pulses and in optical sensors. The rGO coated films were characterized by X-Ray diffraction method (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-Vis absorption spectroscopy (UV-Vis), Photoluminescence (PL) and Scanning electron microscope (SEM) measurements.

  13. Oxidative Homeostasis Regulates the Response to Reductive Endoplasmic Reticulum Stress through Translation Control

    Directory of Open Access Journals (Sweden)

    Shuvadeep Maity

    2016-07-01

    Full Text Available Reductive stress leads to the loss of disulfide bond formation and induces the unfolded protein response of the endoplasmic reticulum (UPRER, necessary to regain proteostasis in the compartment. Here we show that peroxide accumulation during reductive stress attenuates UPRER amplitude by altering translation without any discernible effect on transcription. Through a comprehensive genetic screen in Saccharomyces cerevisiae, we identify modulators of reductive stress-induced UPRER and demonstrate that oxidative quality control (OQC genes modulate this cellular response in the presence of chronic but not acute reductive stress. Using a combination of microarray and relative quantitative proteomics, we uncover a non-canonical translation attenuation mechanism that acts in a bipartite manner to selectively downregulate highly expressed proteins, decoupling the cell’s transcriptional and translational response during reductive ER stress. Finally, we demonstrate that PERK, a canonical translation attenuator in higher eukaryotes, helps in bypassing a ROS-dependent, non-canonical mode of translation attenuation.

  14. Oxygen reduction behavior of rutile-type iridium oxide in sulfuric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Yoshinaga, Norihiro; Sugimoto, Wataru [Department of Fine Materials Engineering, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan); Takasu, Yoshio [Department of Fine Materials Engineering, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda 386-8567 (Japan)], E-mail: ytakasu@shinshu-u.ac.jp

    2008-12-30

    Two different forms of rutile-type iridium oxide catalysts were prepared: IrO{sub 2}-coated titanium plate electrocatalysts prepared by a dip-coating method (IrO{sub 2}/Ti) and iridium oxide nanoparticles (IrO{sub 2}) prepared by a wet method, the Adams fusion method. The catalytic behavior of the oxygen reduction reaction (ORR) was evaluated by cyclic voltammetry in 0.5 M H{sub 2}SO{sub 4} at 60 deg. C. Both catalysts were found to exhibit considerable activity for the ORR; however, the former oxide electrodes showed higher activity than the latter ones. All the IrO{sub 2}/Ti catalyst electrodes heat-treated at a temperature between 400 deg. C and 550 deg. C showed ca. 0.84 V (vs. RHE) of the onset potential for the ORR, E{sub ORR}, where the reduction current of oxygen had begun to be observed during the cathodic potential sweep of the test electrodes. It has been confirmed clearly that IrO{sub 2}, but neither metallic Ir nor the hydrated IrO{sub 2}, behaves as an active catalyst for the ORR in an acidic solution. It was also demonstrated that the enlargement of the surface area of the IrO{sub 2}/Ti with the help of lanthanum is effective for the enhancement of the catalytic activity in the reaction.

  15. Extraction of copper from an oxidized (lateritic) ore using bacterially catalysed reductive dissolution.

    Science.gov (United States)

    Nancucheo, Ivan; Grail, Barry M; Hilario, Felipe; du Plessis, Chris; Johnson, D Barrie

    2014-01-01

    An oxidized lateritic ore which contained 0.8 % (by weight) copper was bioleached in pH- and temperature-controlled stirred reactors under acidic reducing conditions using pure and mixed cultures of the acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans. Sulfur was provided as the electron donor for the bacteria, and ferric iron present in goethite (the major ferric iron mineral present in the ore) acted as electron acceptor. Significantly more copper was leached by bacterially catalysed reductive dissolution of the laterite than in aerobic cultures or in sterile anoxic reactors, with up to 78 % of the copper present in the ore being extracted. This included copper that was leached from acid-labile minerals (chiefly copper silicates) and that which was associated with ferric iron minerals in the lateritic ore. In the anaerobic bioreactors, soluble iron in the leach liquors was present as iron (II) and copper as copper (I), but both metals were rapidly oxidized (to iron (III) and copper (II)) when the reactors were aerated. The number of bacteria added to the reactors had a critical role in dictating the rate and yield of copper solubilised from the ore. This work has provided further evidence that reductive bioprocessing, a recently described approach for extracting base metals from oxidized deposits, has the potential to greatly extend the range of metal ores that can be biomined.

  16. A consistent reaction scheme for the selective catalytic reduction of nitrogen oxides with ammonia

    DEFF Research Database (Denmark)

    Janssens, Ton V.W.; Falsig, Hanne; Lundegaard, Lars Fahl

    2015-01-01

    of the activation of NO by O2 with the fast SCR reaction, enabled by the release of NO2. According to the scheme, the SCR reaction can be divided in an oxidation of the catalyst by NO + O2 and a reduction by NO + NH3; these steps together constitute a complete catalytic cycle. Furthermore both NO and NH3...... are required in the reduction, and, nally, oxidation by NO + O2 or NO2 leads to the same state of the catalyst. These points are shown experimentally for a Cu-CHA catalyst, by combining in situ X-ray absorption spectrosocpy (XAS), electron paramagnetic resonance (EPR), and Fourier transform infrared...... for standard SCR. Finally, the role of a nitrate/nitrite equilibrium and the possible in uence of Cu dimers and Brønsted sites are discussed, and an explanation is offered as to how a catalyst can be effective for SCR, while being a poor catalyst for NO oxidation to NO2....

  17. Oxidative folding and reductive activities of EhPDI, a protein disulfide isomerase from Entamoeba histolytica.

    Science.gov (United States)

    Mares, Rosa E; Magaña, Paloma D; Meléndez-López, Samuel G; Licea, Alexei F; Cornejo-Bravo, José M; Ramos, Marco A

    2009-09-01

    PDI enzymes are oxidoreductases that catalyze oxidation, reduction and isomerization of disulfide bonds in polypeptide substrates. We have previously identified an E. histolytica PDI enzyme (EhPDI) that exhibits oxidase activity in vivo. However, little is known about the specific role of its redox-related structural features on the enzymatic activity. Here, we have studied the in vivo oxidative folding of EhPDI by mutagenic analysis and functional complementation assays as well as the in vitro oxidative folding and reductive activities by comparative kinetics using functional homologues in standard assays. We have found that the active-site cysteine residues of the functional domains (Trx-domains) are essential for catalysis of disulfide bond formation in polypeptides and proteins, such as the bacterial alkaline phosphatase. Furthermore, we have shown that the recombinant EhPDI enzyme has some typical properties of PDI enzymes: oxidase and reductase activities. These activities were comparable to those observed for other functional equivalents, such as bovine PDI or bacterial thioredoxin, under the same experimental conditions. These findings will be helpful for further studies intended to understand the physiological role of EhPDI.

  18. Simple and cost-effective fabrication of size-tunable zinc oxide architectures by multiple size reduction technique

    Directory of Open Access Journals (Sweden)

    Hyeong-Ho Park, Xin Zhang, Seon-Yong Hwang, Sang Hyun Jung, Semin Kang, Hyun-Beom Shin, Ho Kwan Kang, Hyung-Ho Park, Ross H Hill and Chul Ki Ko

    2012-01-01

    Full Text Available We present a simple size reduction technique for fabricating 400 nm zinc oxide (ZnO architectures using a silicon master containing only microscale architectures. In this approach, the overall fabrication, from the master to the molds and the final ZnO architectures, features cost-effective UV photolithography, instead of electron beam lithography or deep-UV photolithography. A photosensitive Zn-containing sol–gel precursor was used to imprint architectures by direct UV-assisted nanoimprint lithography (UV-NIL. The resulting Zn-containing architectures were then converted to ZnO architectures with reduced feature sizes by thermal annealing at 400 °C for 1 h. The imprinted and annealed ZnO architectures were also used as new masters for the size reduction technique. ZnO pillars of 400 nm diameter were obtained from a silicon master with pillars of 1000 nm diameter by simply repeating the size reduction technique. The photosensitivity and contrast of the Zn-containing precursor were measured as 6.5 J cm−2 and 16.5, respectively. Interesting complex ZnO patterns, with both microscale pillars and nanoscale holes, were demonstrated by the combination of dose-controlled UV exposure and a two-step UV-NIL.

  19. Reduction and Immobilization of Potassium Permanganate on Iron Oxide Catalyst by Fluidized-Bed Crystallization Technology

    Directory of Open Access Journals (Sweden)

    Guang-Xia Li

    2012-03-01

    Full Text Available A manganese immobilization technology in a fluidized-bed reactor (FBR was developed by using a waste iron oxide (i.e., BT-3 as catalyst which is a by-product from the fluidized-bed Fenton reaction (FBR-Fenton. It was found that BT-3 could easily reduce potassium permanganate (KMnO4 to MnO2. Furthermore, MnO2 could accumulate on the surface of BT-3 catalyst to form a new Fe-Mn oxide. Laboratory experiments were carried out to investigate the KMnO4-reduction mechanism, including the effect of KMnO4 concentration, BT-3 dosage, and operational solution pH. The results showed that the pH solution was a significant factor in the reduction of KMnO4. At the optimum level, pHf 6, KMnO4 was virtually reduced in 10 min. A pseudo-first order reaction was employed to describe the reduction rate of KMnO4.

  20. Reduction phases of thin iron-oxide nanowires upon thermal treatment and Li exposure

    Energy Technology Data Exchange (ETDEWEB)

    Angelucci, Marco, E-mail: marco.angelucci@gmail.com; Frau, Eleonora; Grazia Betti, Maria [Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185 Roma (Italy); Hassoun, Jusef; Hong, Inchul; Panero, Stefania [Dipartimento di Chimica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185 Roma (Italy); Scrosati, Bruno [IIT, Istituto Italiano di Tecnologia, Genova (Italy); Mariani, Carlo, E-mail: carlo.mariani@uniroma1.it [Dipartimento di Fisica, CNISM, CNIS, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185 Roma (Italy)

    2014-04-28

    Iron oxide nanostructures, a promising alternative to carbon-based anode in lithium-ion batteries, can be produced using a hard template route. This procedure guarantees the formation of Fe{sub 2}O{sub 3} nanowires with comparable diameter and size (average diameter 8 nm) with a dominant cubic γ-phase at the surface. Lithium exposure of the iron oxide nanowires in ultra-high-vacuum (UHV) conditions induces reduction of the Fe ion, leading to a Fe{sub 3}O{sub 4} and then to a Fe{sup 2+} phase, as determined by means of core-level photoemission spectroscopy. Mild annealing of Fe{sub 2}O{sub 3} in UHV determines an oxygen content reduction for the nanowires at lower temperature with respect to the bulk phase. The morphology and the evolution of the electronic properties upon reduction have been compared to those of micro-sized bulk-like grains, to unravel the role of the reduced size and surface-volume ratio.

  1. Microbial reduction of graphene oxide by Escherichia coli: a green chemistry approach.

    Science.gov (United States)

    Gurunathan, Sangiliyandi; Han, Jae Woong; Eppakayala, Vasuki; Kim, Jin-Hoi

    2013-02-01

    Graphene and graphene related materials are an important area of research in recent years due to their unique properties. The extensive industrial application of graphene and related compounds has led researchers to devise novel and simple methods for the synthesis of high quality graphene. In this paper, we developed an environment friendly, cost effective, simple method and green approaches for the reduction of graphene oxide (GO) using Escherichia coli biomass. In biological method, we can avoid use of toxic and environmentally harmful reducing agents commonly used in the chemical reduction of GO to obtain graphene. The biomass of E. coli reduces exfoliated GO to graphene at 37°C in an aqueous medium. The E. coli reduced graphene oxide (ERGO) was characterized with UV-visible absorption spectroscopy, particle analyzer, high resolution X-ray diffractometer, scanning electron microscopy and Raman spectroscopy. Besides the reduction potential, the biomass could also play an important role as stabilizing agent, in which synthesized graphene exhibited good stability in water. This method can open up the new avenue for preparing graphene in cost effective and large scale production. Our findings suggest that GO can be reduced by simple eco-friendly method by using E. coli biomass to produce water dispersible graphene.

  2. Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes

    Institute of Scientific and Technical Information of China (English)

    ZAYAS Pérez Teresa; GEISSLER Gunther; HERNANDEZ Fernando

    2007-01-01

    The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculatio and advanced oxidation processes(AOP)had been studied.The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H202,UVO3 and UV/H-H202/O3 processes was determined under acidic conditions.For each of these processes,different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater.Coffee wastewater is characterized by a high chemical oxygen demand(COD)and low total suspended solids.The outcomes of coffee wastewater reeatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD,color,and turbidity.It was found that a reductiOn in COD of 67%could be realized when the coffee wastewater was treated by chemical coagulation-flocculatlon witll lime and coagulant T-1.When coffee wastewater was treated by coagulation-flocculation in combination with UV/H202,a COD reduction of 86%was achieved,although only after prolonged UV irradiation.Of the three advanced oxidation processes considered,UV/H202,uv/03 and UV/H202/03,we found that the treatment with UV/H2O2/O3 was the most effective,with an efficiency of color,turbidity and further COD removal of 87%,when applied to the flocculated coffee wastewater.

  3. One-pot wet-chemical co-reduction synthesis of bimetallic gold-platinum nanochains supported on reduced graphene oxide with enhanced electrocatalytic activity

    Science.gov (United States)

    Chen, De-Jun; Zhang, Qian-Li; Feng, Jin-Xia; Ju, Ke-Jian; Wang, Ai-Jun; Wei, Jie; Feng, Jiu-Ju

    2015-08-01

    In this work, a simple, rapid and facile one-pot wet-chemical co-reduction method is developed for synthesis of bimetallic Au-Pt alloyed nanochains supported on reduced graphene oxide (Au-Pt NCs/RGO), in which caffeine is acted as a capping agent and a structure-directing agent, while no any seed, template, surfactant or polymer involved. The as-prepared nanocomposites display enlarged electrochemical active surface area, significantly enhanced catalytic activity and better stability for methanol and ethylene glycol oxidation, compared with commercial Pt-C (Pt 50 wt%), PtRu-C (Pt 30 wt% and Ru 15 wt%) and Pt black.

  4. Ce-Fe-O mixed oxide as oxygen carrier for the direct partial oxidation of methane to syngas

    Institute of Scientific and Technical Information of China (English)

    魏永刚; 王华; 李孔斋

    2010-01-01

    The Ce-Fe-O mixed oxide with a ratio of Ce/Fe=7:3, which was prepared by coprecipitation method and employed as oxygen carrier, for direct partial oxidation of methane to syngas in the absence of gaseous oxygen was explored. The mixed oxide was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the catalytic performances were studied in a fixed-bed quartz reactor and a thermogravimetric reactor, respectively. Approximately 99.4% H2 se...

  5. Performance of silica-supported copper oxide sorbents for SO@#x@#/NO@#x@#-removal from flue gas II. Selective catalytic reduction of nitric oxide by ammonia

    NARCIS (Netherlands)

    Kiel, J.H.A.; Kiel, J.H.A.; Edelaar, A.C.S.; Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1992-01-01

    The selective catalytic reduction (SCR) of nitric oxide by ammonia was studied for silica-supported copper oxide particles to be used as a sorbent/catalyst in a continuous process for the simultaneous removal of SOx and NOx from flue gases. The SCR-behaviour was determined as a function of the

  6. Low-temperature synthesis of Mn-based mixed metal oxides with novel fluffy structures as efficient catalysts for selective reduction of nitrogen oxides by ammonia.

    Science.gov (United States)

    Meng, Bo; Zhao, Zongbin; Chen, Yongsheng; Wang, Xuzhen; Li, Yong; Qiu, Jieshan

    2014-10-21

    A series of Mn-based mixed metal oxide catalysts (Co-Mn-O, Fe-Mn-O, Ni-Mn-O) with high surface areas were prepared via low temperature crystal splitting and exhibited extremely high catalytic activity for the low-temperature selective catalytic reduction of nitrogen oxides with ammonia.

  7. Quasi-steady State Reduction of Molecular Motor-Based Models of Directed Intermittent Search

    KAUST Repository

    Newby, Jay M.

    2010-02-19

    We present a quasi-steady state reduction of a linear reaction-hyperbolic master equation describing the directed intermittent search for a hidden target by a motor-driven particle moving on a one-dimensional filament track. The particle is injected at one end of the track and randomly switches between stationary search phases and mobile nonsearch phases that are biased in the anterograde direction. There is a finite possibility that the particle fails to find the target due to an absorbing boundary at the other end of the track. Such a scenario is exemplified by the motor-driven transport of vesicular cargo to synaptic targets located on the axon or dendrites of a neuron. The reduced model is described by a scalar Fokker-Planck (FP) equation, which has an additional inhomogeneous decay term that takes into account absorption by the target. The FP equation is used to compute the probability of finding the hidden target (hitting probability) and the corresponding conditional mean first passage time (MFPT) in terms of the effective drift velocity V, diffusivity D, and target absorption rate λ of the random search. The quasi-steady state reduction determines V, D, and λ in terms of the various biophysical parameters of the underlying motor transport model. We first apply our analysis to a simple 3-state model and show that our quasi-steady state reduction yields results that are in excellent agreement with Monte Carlo simulations of the full system under physiologically reasonable conditions. We then consider a more complex multiple motor model of bidirectional transport, in which opposing motors compete in a "tug-of-war", and use this to explore how ATP concentration might regulate the delivery of cargo to synaptic targets. © 2010 Society for Mathematical Biology.

  8. Simulation of reduction of iron-oxide-carbon composite pellets in a rotary hearth furnace

    Science.gov (United States)

    Halder, Sabuj

    The primary motivation of this work is to evaluate a new alternative ironmaking process which involves the combination of a Rotary Hearth Furnace (RHF) with an iron bath smelter. This work is concerned primarily, with the productivity of the RHF. It is known that the reduction in the RHF is controlled by chemical kinetics of the carbon oxidation and wustite reduction reactions as well as by heat transfer to the pellet surface and within the pellet. It is heat transfer to the pellet which limits the number of layers of pellets in the pellet bed in the RHF and thus, the overall productivity. Different types of carbon like graphite, coal-char and wood charcoal were examined. Part of the research was to investigate the chemical kinetics by de-coupling it from the influence of heat and mass transfer. This was accomplished by carrying out reduction experiments using small iron-oxide-carbon powder composite mixtures. The reaction rate constants were determined by fitting the experimental mass loss with a mixed reaction model. This model accounts for the carbon oxidation by CO2 and wustite reduction by CO, which are the primary rate controlling surface-chemical reactions in the composite system. The reaction rate constants have been obtained using wustite-coal-char powder mixtures and wustite-wood-charcoal mixtures. The wustite for these mixtures was obtained from two iron-oxide sources: artificial porous analytical hematite (PAH) and hematite ore tailings. In the next phase of this study, larger scale experiments were conducted in a RHF simulator using spherical composite pellets. Measurement of the reaction rates was accomplished using off-gas analysis. Different combinations of raw materials for the pellets were investigated. These included artificial ferric oxide as well as naturally existing hematite and taconite ores. Graphite, coal-char and wood-charcoal were the reductants. Experiments were conducted using a single layer, a double layer and a triple layer of

  9. Advanced Chemical Reduction of Reduced Graphene Oxide and Its Photocatalytic Activity in Degrading Reactive Black 5

    Directory of Open Access Journals (Sweden)

    Christelle Pau Ping Wong

    2015-10-01

    Full Text Available Textile industries consume large volumes of water for dye processing, leading to undesirable toxic dyes in water bodies. Dyestuffs are harmful to human health and aquatic life, and such illnesses as cholera, dysentery, hepatitis A, and hinder the photosynthetic activity of aquatic plants. To overcome this environmental problem, the advanced oxidation process is a promising technique to mineralize a wide range of dyes in water systems. In this work, reduced graphene oxide (rGO was prepared via an advanced chemical reduction route, and its photocatalytic activity was tested by photodegrading Reactive Black 5 (RB5 dye in aqueous solution. rGO was synthesized by dispersing the graphite oxide into the water to form a graphene oxide (GO solution followed by the addition of hydrazine. Graphite oxide was prepared using a modified Hummers’ method by using potassium permanganate and concentrated sulphuric acid. The resulted rGO nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV-Vis, X-ray powder diffraction (XRD, Raman, and Scanning Electron Microscopy (SEM to further investigate their chemical properties. A characteristic peak of rGO-48 h (275 cm−1 was observed in the UV spectrum. Further, the appearance of a broad peak (002, centred at 2θ = 24.1°, in XRD showing that graphene oxide was reduced to rGO. Based on our results, it was found that the resulted rGO-48 h nanoparticles achieved 49% photodecolorization of RB5 under UV irradiation at pH 3 in 60 min. This was attributed to the high and efficient electron transport behaviors of rGO between aromatic regions of rGO and RB5 molecules.

  10. Graphene-based transition metal oxide nanocomposites for the oxygen reduction reaction

    Science.gov (United States)

    Sun, Meng; Liu, Huijuan; Liu, Yang; Qu, Jiuhui; Li, Jinghong

    2015-01-01

    The development of low cost, durable and efficient nanocatalysts to substitute expensive and rare noble metals (e.g. Pt, Au and Pd) in overcoming the sluggish kinetic process of the oxygen reduction reaction (ORR) is essential to satisfy the demand for sustainable energy conversion and storage in the future. Graphene based transition metal oxide nanocomposites have extensively been proven to be a type of promising highly efficient and economic nanocatalyst for optimizing the ORR to solve the world-wide energy crisis. Synthesized nanocomposites exhibit synergetic advantages and avoid the respective disadvantages. In this feature article, we concentrate on the recent leading works of different categories of introduced transition metal oxides on graphene: from the commonly-used classes (FeOx, MnOx, and CoOx) to some rare and heat-studied issues (TiOx, NiCoOx and Co-MnOx). Moreover, the morphologies of the supported oxides on graphene with various dimensional nanostructures, such as one dimensional nanocrystals, two dimensional nanosheets/nanoplates and some special multidimensional frameworks are further reviewed. The strategies used to synthesize and characterize these well-designed nanocomposites and their superior properties for the ORR compared to the traditional catalysts are carefully summarized. This work aims to highlight the meaning of the multiphase establishment of graphene-based transition metal oxide nanocomposites and its structural-dependent ORR performance and mechanisms.

  11. Sulfide oxidation and nitrate reduction for potential mitigation of H2S in landfills.

    Science.gov (United States)

    Fang, Yuan; Du, Yao; Feng, Huan; Hu, Li-Fang; Shen, Dong-Sheng; Long, Yu-Yang

    2015-04-01

    Because H2S emitted by landfill sites has seriously endangered human health, its removal is urgent. H2S removal by use of an autotrophic denitrification landfill biocover has been reported. In this process, nitrate-reducing and sulfide-oxidizing bacteria use a reduced sulfur source as electron donor when reducing nitrate to nitrogen gas and oxidizing sulfur compounds to sulfate. The research presented here was performed to investigate the possibility of endogenous mitigation of H2S by autotrophic denitrification of landfill waste. The sulfide oxidation bioprocess accompanied by nitrate reduction was observed in batch tests inoculated with mineralized refuse from a landfill site. Repeated supply of nitrate resulted in rapid oxidation of the sulfide, indicating that, to a substantial extent, the bioprocess may be driven by functional microbes. This bioprocess can be realized under conditions suitable for the autotrophic metabolic process, because the process occurred without addition of acetate. H2S emissions from landfill sites would be substantially reduced if this bioprocess was introduced.

  12. Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle.

    Science.gov (United States)

    Kumar, Dinesh; Lee, Ah-Reum; Kaur, Sandeep; Lim, Dong-Kwon

    2015-09-22

    Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using visible light irradiation with plasmonic nanoparticles. The plasmonic nanoparticle is used to improve the reduction efficiency of GO. It only takes 30 min at RT by illuminating the solutions with Xe-lamp, the r-GO solutions can be obtained by completely removing gold nanoparticles through simple centrifugation step. The spherical gold nanoparticles (AuNPs) as compared to the other nanostructures is the most suitable plasmonic nanostructure for r-GO preparation. The reduced graphene oxide prepared using visible light and AuNPs was equally qualitative as chemically reduced graphene oxide, which was supported by various analytical techniques such as UV-Vis spectroscopy, Raman spectroscopy, powder XRD and XPS. The reduced graphene oxide prepared with visible light shows excellent quenching properties over the fluorescent molecules modified on ssDNA and excellent fluorescence recovery for target DNA detection. The r-GO prepared by recycled AuNPs is found to be of same quality with that of chemically reduced r-GO. The use of visible light with plasmonic nanoparticle demonstrates the good alternative method for r-GO synthesis.

  13. Preparation of silver tin oxide powders by hydrothermal reduction and crystallization

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Silver tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw marrials. H2C2O4 was used as the co-precipitator of silver ions and tin ions. The co-precipitation conditions were investigated. The results show that the co-precipitate of Ag2C2O4 and Sn(OH)4 is available when the pH value of the solution is 4.27-8.36. Using the obtained precipitate as precursor, the reduction of Ag+ and the crystallization of tin oxide were carried out simultaneonsly by the hydrothermal method and silver tin oxide composite powders were obtained. The composite powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and energy spectrum analysis. The results show that the silver tin oxide composite powders are small with a diameter of about 2 μm and with homogeneous distribution of tin.

  14. Oxidation-Reduction Potential as a Biomarker for Severity and Acute Outcome in Traumatic Brain Injury

    Directory of Open Access Journals (Sweden)

    Kimberly B. Bjugstad

    2016-01-01

    Full Text Available There are few reliable markers for assessing traumatic brain injury (TBI. Elevated levels of oxidative stress have been observed in TBI patients. We hypothesized that oxidation-reduction potential (ORP could be a potent biomarker in TBI. Two types of ORP were measured in patient plasma samples: the static state of oxidative stress (sORP and capacity for induced oxidative stress (icORP. Differences in ORP values as a function of time after injury, severity, and hospital discharge were compared using ANOVAs with significance at p≤0.05. Logit regression analyses were used to predict acute outcome comparing ORP, Injury Severity Score (ISS, Abbreviated Injury Scale (AIS, and Glasgow Coma Scale (GCS. Antioxidant capacity (icORP on day 4 was prognostic for acute outcomes (p 7.25 μC. IcORP was a better predictor than ISS, AIS, or GCS scores. sORP increased in those with the highest ISS values (p<0.05. Based on these findings ORP is useful biomarker for severity and acute outcome in TBI patients. Changes in ORP values on day 4 after injury were the most prognostic, suggesting that patients’ response to brain injury over time is a factor that determines outcome.

  15. H{sub 2} from biosyngas via iron reduction and oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Straus, J.; Terry, P. [H Power Corp., Belleville, NJ (United States)

    1995-09-01

    The production of hydrogen from the steam-oxidation of iron is a long-known phenomenon. The rise in interest in the production and storage of hydrogen justifies the examination of this process (and of the reverse process, the reduction of iron oxide) for commercial use. Under NREL subcontract ZAR-4-13294-02, a process simulation program was developed and used as a design tool to analyze various configurations of the iron-hydrogen purification/storage scheme. Specifically, analyses were performed to determine the effectiveness of this scheme in conjunction with biomass-derived gasified fuel streams (biosyngas). The results of the computer simulations led to a selection of a two-stage iron oxide reduction process incorporating interstage water and CO{sub 2} removal. Thermal analysis shows that the iron-hydrogen process would yield essentially the same quantity of clean hydrogen per unit of biomass as the conventional route. The iron-hydrogen process benefits from the excellent match potentially achievable between the otherwise-unusable energy fraction in the off-gas of the reduction reactor and the parasitic thermal, mechanical and electrical energy needs of some typical gasifier systems. The program simulations and economic analysis suggest that clean hydrogen from biomass feedstock could cost about 20% less via the iron-hydrogen method than by conventional methods of purification (using the same feedstock). Cost analyses show that lower capital costs would be incurred in generating clean hydrogen by utilizing this approach, especially in response to the fluctuating demand profile of a utility.

  16. Directing-group-assisted copper-catalyzed oxidative esterification of phenols with aldehydes.

    Science.gov (United States)

    Zheng, Yong; Song, Wei-Bin; Xuan, Li-Jiang

    2015-11-28

    A directing-group-assisted copper-catalyzed oxidative esterification of phenols with aldehydes using TBHP as an oxidant was described. This methodology which showed the advantages of base, ligand free, short routes and functional group tolerance could be used as an alternative protocol for the classical esterification reactions.

  17. Direct chemical vapour deposited grapheme synthesis on silicon oxide by controlled copper dewettting

    NARCIS (Netherlands)

    van den Beld, Wesley Theodorus Eduardus; van den Berg, Albert; Eijkel, Jan C.T.

    2015-01-01

    In this paper we present a novel method for direct uniform graphene synthesis onto silicon oxide in a controlled manner. On a grooved silicon oxide wafer is copper deposited under a slight angle and subsequently the substrate is treated by a typical graphene synthesis process. During this process

  18. Effect of Yttrium on High Temperature Oxidation Resistance of a Directionally Solidified Superalloy

    Institute of Scientific and Technical Information of China (English)

    宋立国; 李树索; 郑运荣; 韩雅芳

    2004-01-01

    The effect of rare earth element yttrium on the high temperature oxidation resistance of a directionally solidified Ni-base superalloy was studied with scanning electron microscopy(SEM), energy dispersive spectrum(EDS)and X-ray diffraction(XRD)techniques. The results show that the oxidation resistance of the alloy is substantially improved by adding proper amount of yttrium.

  19. Direct chemical vapour deposited grapheme synthesis on silicon oxide by controlled copper dewettting

    NARCIS (Netherlands)

    Beld, van den Wesley T.E.; Berg, van den Albert; Eijkel, Jan C.T.

    2015-01-01

    In this paper we present a novel method for direct uniform graphene synthesis onto silicon oxide in a controlled manner. On a grooved silicon oxide wafer is copper deposited under a slight angle and subsequently the substrate is treated by a typical graphene synthesis process. During this process di

  20. Investigation of NOx Reduction by Low Temperature Oxidation Using Ozone Produced by Dielectric Barrier Discharge

    DEFF Research Database (Denmark)

    Stamate, Eugen; Irimiea, Cornelia; Salewski, Mirko

    2013-01-01

    NOx reduction by low temperature oxidation using ozone produced by a dielectric barrier discharge generator is investigated for different process parameters in a 6m long reactor in serpentine arrangement using synthetic dry flue gas with NOx levels below 500 ppm, flows up to 50 slm and temperatures...... up to 80 C. The role of different mixing schemes and the impact of a steep temperature gradient are also taken into consideration. The process chemistry is monitored by Fourier transform infrared spectroscopy, chemiluminescence and absorption spectroscopy. The kinetic mechanism during the mixing...

  1. Reductive dissolution of Mn oxides in river-recharged aquifers: a laboratory column study

    Science.gov (United States)

    Petrunic, B. M.; MacQuarrie, K. T. B.; Al, T. A.

    2005-01-01

    River-recharged aquifers are developed for drinking water supplies in many parts of the world. Often, however, dissolved organic carbon (DOC) present in the infiltrating river water causes biogeochemical reactions to occur in the adjacent aquifer that create elevated Mn and Fe. Mn concentrations in groundwater from some of the production wells installed in the aquifer at Fredericton, New Brunswick exceed the Canadian Drinking Water Guideline of 9.1×10 -4 mmol/l by up to 5.5×10 -2 mmol/l. It has previously been hypothesized that the influx of DOC from the Saint John River is causing bacterially mediated reductive dissolution of Mn oxides in the aquifer system, leading to elevated aqueous Mn concentrations. Previous work was limited to the collection of water samples from production wells and several observation wells installed in the glacial outwash aquifer. The objective of this study was to investigate the biogeochemical controls on Mn concentrations using sand-filled columns. One column was inoculated with bacteria while a second column was treated with ethanol in order to decrease the microbial population initially present in the system. Both columns received the same influent solution that contained acetate as a source of DOC. The results of the experiments suggested that the two main controls on Mn concentrations in the columns were microbially mediated reductive dissolution of Mn oxides and cation exchange. The conceptual model that was developed based on the experimental data was supported by the results obtained using a one-dimensional reactive-transport model. The reductive dissolution of Mn oxides in the aquifer sands could be adequately simulated using dual-Monod kinetics. Similar trends are observed in the experimental data and field data collected from Production Well 5, located in the Fredericton Aquifer. From the experiments, it is evident that cation-exchange reactions may be an important geochemical control on Mn concentrations during the initial

  2. Note: Rapid reduction of graphene oxide paper by glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bo, Zheng; Qian, Jiajing; Duan, Liangping; Qiu, Kunzan, E-mail: qiukz@zju.edu.cn; Yan, Jianhua; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Han, Zhao Jun [CSIRO Manufacturing Flagship, P.O. Box 218, Bradfield Road, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [CSIRO Manufacturing Flagship, P.O. Box 218, Bradfield Road, Lindfield, New South Wales 2070 (Australia); Institute for Future Environments and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland 4000 (Australia)

    2015-05-15

    This note reports on a novel method for the rapid reduction of graphene oxide (GO) paper using a glow discharge plasma reactor. Glow discharge is produced and sustained between two parallel-plate graphite electrodes at a pressure of 240 mTorr. By exposing GO paper at the junction of negative-glow and Faraday-dark area for 4 min, the oxygen-containing groups can be effectively removed (C/O ratio increases from 2.6 to 7.9), while the material integrality and flexibility are kept well. Electrochemical measurements demonstrate that the as-obtained reduced GO paper can be potentially used for supercapacitor application.

  3. Electrocatalytic reduction of carbon dioxide on post-transition metal and metal oxide nanoparticles

    Science.gov (United States)

    White, James L.

    The electroreduction of carbon dioxide to liquid products is an important component in the utilization of CO2 and in the high-density storage of intermittent renewable energy in the form of chemical bonds. Materials based on indium and tin, which yield predominantly formic acid, have been investigated in order to gain a greater understanding of the electrochemically active species and the mechanism of CO2 reduction on these heavy post-transition metals, since prior studies on the bulk metals did not provide thermodynamically sensible reaction pathways. Nanoparticles of the oxides and hydroxides of tin and indium have been prepared and characterized by transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and various electrochemical methods in order to obtain structural information and analyze the role of various surface species on the CO2 reduction pathway. On both indium and tin, metastable surface-bound hydroxides bound CO2 and formed metal carbonates, which can then be reduced electrochemically. The relevant oxidation state of tin was suggested to be SnII rather than SnIV, necessitating a pre reduction to generate the CO2-binding species. Metallic indium nanoparticles partially oxidized in air and became highly efficient CO2 reduction electrocatalysts. Unit Faradaic efficiencies for formate, much higher than on bulk indium, were achieved with only 300 mV of overpotential on these particles, which possessed an oxyhydroxide shell surrounding a conductive metallic core. Alloys and mixed-metal oxide and hydroxide particles of tin and indium have also been studied for their carbon dioxide electrocatalytic capabilities, especially in comparison to the pure metal species. Additionally, a solar-driven indium-based CO2 electrolyzer was developed to investigate the overall efficiency for intermittent energy storage. The three flow cells were powered by a commercial photovoltaic array and had a maximum conversion efficiency of incident

  4. Selective catalytic reduction of sulfur dioxide by carbon monoxide over iron oxide supported on activated carbon

    OpenAIRE

    2014-01-01

    The selective reduction of sulfur dioxide with carbon monoxide to elemental sulfur was studied over AC-supported transition-metal oxide catalysts. According to the study, Fe2O3/AC was the most active catalyst among the 4 AC-supported catalysts tested. By using Fe2O3/AC, the best catalyst, when the feed conditions were properly optimized (CO/SO2 molar ratio = 2:1; sulfidation temperature, 400 °C; Fe content, 20 wt%; GHSV = 7000 mL g-1 h-1), 95.43% sulfur dioxide conversion and 86.59% sulfur yi...

  5. Radiolytic reactions of nitro blue tetrazolium under oxidative and reductive conditions: a pulse radiolysis study

    Science.gov (United States)

    Kovacs, A.; Wojnarovits, L.; Baranyai, M.; Moussa, A.; Othman, I.; McLaughlin, W. L.

    1999-08-01

    The radiolytic reactions of the ditetrazolium salt nitro blue tetrazolium chloride (NBTCl 2) were studied by pulse radiolysis technique in aqueous solution under reducing and oxidising conditions with the aim of potential dosimetry application. Under reducing conditions the fast formation of the tetrazolinyl radical is observed that is followed by the appearance of monoformazan (MF +), i.e. one of the tetrazolium rings is reduced to formazan. The formation of the water-insoluble diformazan, i.e. the result of the second reduction step was not observed in pulse radiolysis. Formazan formation was not found under oxidative conditions.

  6. Development of Head-end Pyrochemical Reduction Process for Advanced Oxide Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Park, B. H.; Seo, C. S.; Hur, J. M.; Jeong, S. M.; Hong, S. S.; Choi, I. K.; Choung, W. M.; Kwon, K. C.; Lee, I. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-12-15

    The development of an electrolytic reduction technology for spent fuels in the form of oxide is of essence to introduce LWR SFs to a pyroprocessing. In this research, the technology was investigated to scale a reactor up, the electrochemical behaviors of FPs were studied to understand the process and a reaction rate data by using U{sub 3}O{sub 8} was obtained with a bench scale reactor. In a scale of 20 kgHM/batch reactor, U{sub 3}O{sub 8} and Simfuel were successfully reduced into metals. Electrochemical characteristics of LiBr, LiI and Li{sub 2}Se were measured in a bench scale reactor and an electrolytic reduction cell was modeled by a computational tool.

  7. Oxygen reduction and transportation mechanisms in solid oxide fuel cell cathodes

    Science.gov (United States)

    Li, Yihong; Gemmen, Randall; Liu, Xingbo

    In recent years, various models have been developed for describing the reaction mechanisms in solid oxide fuel cell (SOFC) especially for the cathode electrode. However, many fundamental issues regarding the transport of oxygen and electrode kinetics have not been fully understood. This review tried to summarize the present status of the SOFC cathode modeling efforts, and associated experimental approaches on this topic. In addition, unsolved problems and possible future research directions for SOFC cathode kinetics had been discussed.

  8. Efficient control of ultrafast optical nonlinearity of reduced graphene oxide by infrared reduction

    Energy Technology Data Exchange (ETDEWEB)

    Bhattachraya, S.; Maiti, R.; Das, A. C.; Saha, S.; Mondal, S.; Ray, S. K.; Bhaktha, S. N. B.; Datta, P. K., E-mail: pkdatta.iitkgp@gmail.com [Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2016-07-07

    Simultaneous occurrence of saturable absorption nonlinearity and two-photon absorption nonlinearity in the same medium is well sought for the devices like optical limiter and laser mode-locker. Pristine graphene sheet consisting entirely of sp{sup 2}-hybridized carbon atoms has already been identified having large optical nonlinearity. However, graphene oxide (GO), a precursor of graphene having both sp{sup 2} and sp{sup 3}-hybridized carbon atom, is increasingly attracting cross-discipline researchers for its controllable properties by reduction of oxygen containing groups. In this work, GO has been prepared by modified Hummers method, and it has been further reduced by infrared (IR) radiation. Characterization of reduced graphene oxide (RGO) by means of Raman spectroscopy, X-ray photoelectron spectroscopy, and UV-Visible absorption measurements confirms an efficient reduction with infrared radiation. Here, we report precise control of non-linear optical properties of RGO in femtosecond regime with increased degrees of IR reduction measured by open aperture z-scan technique. Depending on the intensity, both saturable absorption and two-photon absorption effects are found to contribute to the non-linearity of all the samples. Saturation dominates at low intensity (∼127 GW/cm{sup 2}) while two-photon absorption becomes prominent at higher intensities (from 217 GW/cm{sup 2} to 302 GW/cm{sup 2}). The values of two-photon absorption co-efficient (∼0.0022–0.0037 cm/GW for GO, and ∼0.0128–0.0143 cm/GW for RGO) and the saturation intensity (∼57 GW/cm{sup 2} for GO, and ∼194 GW/cm{sup 2} for RGO) increase with increasing reduction, indicating GO and RGO as novel tunable photonic devices. We have also explained the reason of tunable nonlinear optical properties by using amorphous carbon model.

  9. Reduction of graphene oxide nanosheets by natural beta carotene and its potential use as supercapacitor electrode

    Directory of Open Access Journals (Sweden)

    Rubaiyi M. Zaid

    2015-07-01

    Full Text Available A green, non-toxic and eco-friendly approach for the reduction of graphene oxide (GO nanosheets using natural β-carotene is reported. The FTIR spectroscopy and thermogravimetric analyses reveal the oxygen scavenging property of β-carotene successfully removes oxygen functionalities on GO nanosheets. Complete GO reduction is achieved within 16 h with 10 mM β-carotene as confirmed by the UV spectroscopy results. The high resolution transmission electron microscopy images provide clear evidence for the formation of few layers of graphene nanosheets. Furthermore, the mechanism of GO reduction by β-carotene has been proposed in this study. The electrochemical testing shows good charge storage properties of β-carotene reduced GO (142 F/g at 10 mV/s; 149 F/g at 1 A/g in Na2SO4, with stable cycling (89% for up to 1000 cycles. The findings suggest the reduction of GO nanosheets by β-carotene is a suitable approach in producing graphene nanosheets for supercapacitor electrode.

  10. X-ray absorption spectroscopy study on the thermal and hydrazine reduction of graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Xianqing, E-mail: lxq@gxu.edu.cn [The Colleague of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Wang, Yu [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China); Zheng, Huiyuan [The Colleague of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Wu, Ziyu, E-mail: wuzy@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China)

    2014-10-15

    Highlights: • XAS study of GO and reduced GO was performed. • Detailed evolution of the electronic structures and chemical bonding of GO was revealed. • A new efficient route for the reduction of GO is proposed. - Abstract: X-ray absorption spectroscopy (XAS) was applied to systemically investigate the deoxygenation of graphene oxide (GO) via annealing and hydrazine treatment. Detailed evolution of the electronic structures and chemical bonding of GO was presented. The enhanced intensity of π{sup *} resonance and the appearance of splitting σ{sup *} resonance in C K-edge XAS spectra suggest high extents of recoveries of π-conjugation upon reduction using thermal annealing or hydrazine. Experimental results revealed that the carboxyl as well as epoxide and hydroxyl groups on the surface of GO were thermally reduced first, followed by the more difficult removal of carbonyl and cyclic ether groups at higher temperatures. The hydrazine reduction could remove epoxide, hydroxyl and carboxyl groups effectively, whereas the carbonyl groups were partially reduced with the incorporation of nitrogen species simultaneously. The residual oxygen functional groups on hydrazine-reduced GO could be further removed after modest thermal annealing. It was proposed that a combination of both types of reductions would give the best deoxygenation efficiency for the production of graphene.

  11. Graphene oxide-facilitated reduction of nitrobenzene in sulfide-containing aqueous solutions.

    Science.gov (United States)

    Fu, Heyun; Zhu, Dongqiang

    2013-05-07

    The main objective of this study was to test the possibility that graphene-based nanomaterials can mediate environmentally relevant abiotic redox reactions of organic contaminants. We investigated the effect of graphene oxide (GO) on the reduction of nitrobenzene by Na2S in aqueous solutions. With the presence of GO (typically 5 mg/L), the observed pseudofirst-order rate constant (kobs) for the reduction of nitrobenzene was raised by nearly 2 orders of magnitude (from 7.83 × 10(-5) h(-1) to 7.77 × 10(-3) h(-1)), strongly suggesting reaction mediation by GO. As reflected by the combined spectroscopic analyses, GO was reduced in the beginning of the reaction, and hence the reduced GO (RGO) mediated the reduction of nitrobenzene. It was proposed that the zigzag edges of RGO acted as the catalytic active sites, while the basal plane of RGO served as the conductor for the electron transfer during the catalytic process. Furthermore, changing the pH (5.9-9.1) and the presence of dissolved humic acid (10 mg TOC/L) were found to greatly influence the catalytic activity of RGO. The results imply that graphene-based nanomaterials may effectively mediate the reductive transformation of nitroaromatic compounds and can contribute to the natural attenuation and remediation of these chemicals.

  12. Accelerated creep in solid oxide fuel cell anode supports during reduction

    Science.gov (United States)

    Frandsen, H. L.; Makowska, M.; Greco, F.; Chatzichristodoulou, C.; Ni, D. W.; Curran, D. J.; Strobl, M.; Kuhn, L. T.; Hendriksen, P. V.

    2016-08-01

    To evaluate the reliability of solid oxide fuel cell (SOFC) stacks during operation, the stress field in the stack must be known. During operation the stress field will depend on time as creep processes relax stresses. The creep of reduced Ni-YSZ anode support at operating conditions has been studied previously. In this work a newly discovered creep phenomenon taking place during the reduction is reported. This relaxes stresses at a much higher rate (∼×104) than creep during operation. The phenomenon was studied both in three-point bending and uniaxial tension. Differences between the two measurements could be explained by newly observed stress promoted reduction. Finally, samples exposed to a small tensile stress (∼0.004 MPa) were observed to expand during reduction, which is in contradiction to previous literature. These observations suggest that release of internal residual stresses between the NiO and the YSZ phases occurs during reduction. The accelerated creep should practically eliminate any residual stress in the anode support in an SOFC stack, as has previously been indirectly observed. This phenomenon has to be taken into account both in the production of stacks and in the simulation of the stress field in a stack based on anode supported SOFCs.

  13. Development of direct hydrocarbon solid oxide fuel cells

    Science.gov (United States)

    McIntosh, Steven

    The focus of this dissertation is the development of a Solid Oxide Fuel Cell (SOFC) that can operate with hydrocarbon fuels without the need for pre-reforming. The design of an active SOFC anode requires the consideration of a number of factors including the catalytic activity of the electrode towards fuel oxidation and electronic conductivity. This work focuses on a novel system for anode fabrication that allows the catalytically active and electronically conducting components of the anode to be easily varied. The catalytic properties of the SOFC anode were examined and a strong link between SOFC performance and oxidation activity demonstrated. Of the rare-earth catalysts investigated ceria was found to have the highest activity leading to the highest fuel cell power density. This activity was further improved, especially for methane fuel, by doping with a precious metal. Furthermore, it was shown that the catalyst not only increased the rate of reaction but increased the cell Open-Circuit Voltage (OCV) suggesting a change in mechanism that increased the cell efficiency. The necessity for high electronic conductivity and connectivity in the electrode was elucidated by studying the impact of anode copper content on cell performance. Low copper loading led to reduced cell performance due to a lack of conductive pathways from the active electrode region to the external circuit. It was observed that additional conductivity was provided by a thermally deposited carbonaceous phase formed upon exposure to hydrocarbon fuels. The electrochemical characterization of SOFC electrodes is a non-trivial problem. Literature reports on the properties of similar electrodes are inconsistent and often contradictory. Using a combined experimental and theoretical approach, significant problems were found with common experimental procedures used to separate the losses associated the cell cathode from those of the anode. By calculating the effect of test geometry on this separation, it

  14. Effect of sulfur compounds on biological reduction of nitric oxide in aqueous Fe(II)EDTA2- solutions

    NARCIS (Netherlands)

    Manconi, I.; Maas, van der P.M.F.; Lens, P.N.L.

    2006-01-01

    Biological reduction of nitric oxide (NO) in aqueous solutions of EDTA chelated Fe(II) is one of the main steps in the BioDeNOx process, a novel bioprocess for the removal of nitrogen oxides (NOx) from polluted gas streams. Since NOx contaminated gases usually also contain sulfurous pollutants, the

  15. Direct Partial Oxidation of Natural Gas to Liquid Chemicals

    DEFF Research Database (Denmark)

    Rasmussen, Christian Lund

    2007-01-01

    eksperimenter udført under veldefinerede betingelser. Dette arbejde har ført til udviklingen af en ny, detaljeret kemisk kinetisk mode, der beskriver forbrændingskemien for H2/O2, CO/CO2 og C1-2-kulbrinter med/uden tilsætning af NOx samt, i et begrænset omfang, også SO2, under højt tryk og middelhøje......Direkte delvis oxidation af naturgas til flydende kemikalier er en attraktiv industriel proces, hvor naturgas omdannes til stoffer; primært methanol (CH3OH) som let kan transporteres over store afstande. Omdannelsen sker i en simpel et-trinsproces under højt tryk, lave forbrændingstemperaturer...

  16. Direct Electrolytic Reduction of Solid Ta2O5 to Ta with SOM Process

    Science.gov (United States)

    Chen, Chaoyi; Yang, Xiaqiong; Li, Junqi; Lu, Xionggang; Yang, Shufeng

    2016-06-01

    A process that uses the solid-oxide-oxygen-ion conducting membrane has been investigated to produce tantalum directly from solid Ta2O5 in molten CaCl2 or a molten mixture of 55.5MgF2-44.5CaF2 (in wt pct). The sintered porous Ta2O5 pellet was employed as the cathode, while the liquid copper alloy, saturated with graphite powder and encased in a one-end-closed yttria-stabilized-zirconia (YSZ) tube, acted as the anode. The electrolysis potential in this method is higher than that of the Fray-Farthing-Chen Cambridge process because the YSZ membrane tube blocks the melts to electrolyze, and only Ta2O5 is will be electrolyzed. The microstructures of reduced pellets and a cyclic voltammogram of solid Ta2O5 in molten CaCl2 were analyzed. In addition, the influence of particle size and porosity of the cathode pellets on metal-oxide-electrolyte, three-phase interlines was also discussed. The results demonstrate that the sintering temperature of cathode pellets and electrolytic temperature play important roles in the electrochemical process. Furthermore, this process can be used to produce Ta metal efficiently without the expensive cost of pre-electrolysis and generation of harmful by-products.

  17. Copper-substituted perovskite compositions for solid oxide fuel cell cathodes and oxygen reduction electrodes in other electrochemical devices

    Science.gov (United States)

    Rieke, Peter C.; Coffey, Gregory W.; Pederson, Larry R.; Marina, Olga A.; Hardy, John S.; Singh, Prabhaker; Thomsen, Edwin C.

    2010-07-20

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells. Also provided are electrochemical devices that include active oxygen reduction electrodes, such as solid oxide fuel cells, sensors, pumps and the like. The compositions comprises a copper-substituted ferrite perovskite material. The invention also provides novel methods for making and using the electrode compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having cathodes comprising the compositions.

  18. Isolation of microorganisms involved in reduction of crystalline iron(III oxides in natural environments

    Directory of Open Access Journals (Sweden)

    Tomoyuki eHori

    2015-05-01

    Full Text Available Reduction of crystalline Fe(III oxides is one of the most important electron sinks for organic compound oxidation in natural environments. Yet a limited number of isolates makes it difficult to understand physiology and ecological impact of the microorganisms involved. Here, two-staged cultivation was implemented to selectively enrich and isolate crystalline iron(III reducers in soils and sediments. Firstly, iron reducers were enriched and other untargeted eutrophs were depleted by two-year successive culture on a crystalline ferric iron oxide (i.e., goethite, lepidocrocite, hematite, or magnetite as electron acceptor. Fifty-eight out of 136 incubation conditions allowed the continued existence of microorganisms as confirmed by PCR amplification. High-throughput Illumina sequencing based on 16S rRNA genes revealed that the enrichment cultures on each of the ferric iron oxides contained bacteria belonging to the Deltaproteobacteria (mainly Geobacteraceae, followed by Firmicutes and Chloroflexi, which also comprised most of the operational taxonomic units (OTUs identified. The Venn diagrams indicated that the core OTUs enriched with all of the iron oxides were dominant in the Geobacteraceae. Secondly, 38 enrichment cultures including novel microorganisms were transferred to soluble-iron(III media in order to stimulate proliferation of the enriched iron reducers. Through extinction dilution-culture and single colony isolation, six strains within the Deltaproteobacteria were finally obtained; five strains belonged to the genus Geobacter and one strain to Pelobacter. These isolates had 94.8–98.1% sequence similarities of 16S rRNA genes to cultured relatives. All the isolates were able to grow on acetate and ferric iron but their physiological characteristics differed considerably in terms of growth rate. The results demonstrate the successful enrichment and isolation of novel iron(III reducers that were able to thrive by reducing highly

  19. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Dong Rip, E-mail: dongrip@hanyang.ac.kr [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-06-15

    Graphical abstract: - Highlights: • Cerium oxide nanorods were uniformly grown on diverse substrates. • Changes in growth conditions led to morphology evolution of cerium oxide nanostructures. • The grown cerium oxide nanostructures were single or poly crystalline. • Direct growth of cerium oxide nanorods made the diverse substrates superhydrophobic and anti-corrosive without any surface modifiers. - Abstract: Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

  20. Influence of Short-time Oxidation on Corrosion Properties of Directionally Solidified Superalloys with Different Orientations

    Directory of Open Access Journals (Sweden)

    MA Luo-ning

    2016-07-01

    Full Text Available In order to investigate the corrosion performance on intersecting and longitudinal surfaces of unoxidized and oxidized directionally solidified superalloys, Ni-base directionally solidified superalloy DZ125 and Co-base directionally solidified superalloy DZ40M were selected. Oxidation behavior on both alloys with different orientations was investigated at 1050℃ at different times, simulating the oxidation process of vanes or blades in service; subsequent electrochemical performance in 3.5%NaCl aqueous solution was studied on two orientations of unoxidized and oxidized alloys, simulating the corrosion process of superalloy during downtime. The results show that grain boundaries and sub-boundaries of directionally solidified superalloys are susceptible to corrosion and thus longitudinal surface with lower area fraction of grain boundaries has higher corrosion resistance. Compared to intersecting surface of alloys, the structure of grain boundaries of longitudinal surface is less conducive to diffusion and thus the oxidation rate on longitudinal surface is lower. Formation of oxide layers on alloys after short-time oxidation provides protective effect and enhances the corrosion resistance.

  1. Reduction of Sulphur-containing Aromatic Nitro Compounds with Hydrazine Hydrate over Iron(Ⅲ) Oxide-MgO Catalyst

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Sulphur-containing aromatic amines were prepared efficiently in good to excellent yields by reduction of the corresponding sulphur-containing aromatic nitro compounds with hydrazine hydrate in the presence of iron(Ⅲ) oxide-MgO catalyst. The catalyst exhibited high activity and stability for the reduction of sulphur-containing aromatic nitro compounds. The yields of sulphur-containing aromatic amines were up to 91-99 % at 355 K after reduction for 1-4 h over this catalyst.

  2. Photocatalytic Decolourization of Direct Yellow 9 on Titanium and Zinc Oxides

    Directory of Open Access Journals (Sweden)

    Elżbieta Regulska

    2013-01-01

    Full Text Available The photodecolourization of Direct Yellow 9, a member of the group of azo dyes which are commonly used in the various branches of the industry, was investigated. The photostability of this dye was not previously examined. Photocatalytic degradation method was evaluated. Solar simulated light (E=500 W/m2, titanium dioxide, and zinc oxide were used as irradiation source and photocatalysts, respectively. Kinetic studies were performed on a basis of a spectrophotometric method. Degradation efficiency was assessed by applying high performance liquid chromatography. Disappearance of a dye from titanium dioxide and zinc oxide surfaces after degradation was confirmed by thermogravimetry and Raman microscopy. Direct Yellow 9 was found to undergo the photodegradation with approximately two times higher efficiency when zinc oxide was applied in comparison with titanium dioxide. A simple and promising way to apply the photocatalytic removal of Direct Yellow 9 in titanium dioxide and zinc oxide suspensions was presented.

  3. Influence of protein interactions on oxidation/reduction midpoint potentials of cofactors in natural and de novo metalloproteins.

    Science.gov (United States)

    Olson, T L; Williams, J C; Allen, J P

    2013-01-01

    As discussed throughout this special issue, oxidation and reduction reactions play critical roles in the function of many organisms. In photosynthetic organisms, the conversion of light energy drives oxidation and reduction reactions through the transfer of electrons and protons in order to create energy-rich compounds. These reactions occur in proteins such as cytochrome c, a heme-containing water-soluble protein, the bacteriochlorophyll-containing reaction center, and photosystem II where water is oxidized at the manganese cluster. A critical measure describing the ability of cofactors in proteins to participate in such reactions is the oxidation/reduction midpoint potential. In this review, the basic concepts of oxidation/reduction reactions are reviewed with a summary of the experimental approaches used to measure the midpoint potential of metal cofactors. For cofactors in proteins, the midpoint potential not only depends upon the specific chemical characteristics of cofactors but also upon interactions with the surrounding protein, such as the nature of the coordinating ligands and protein environment. These interactions can be tailored to optimize an oxidation/reduction reaction carried out by the protein. As examples, the midpoint potentials of hemes in cytochromes, bacteriochlorophylls in reaction centers, and the manganese cluster of photosystem II are discussed with an emphasis on the influence that protein interactions have on these potentials. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.

  4. Syntrophic Effects in a Subsurface Clostridial Consortium on Fe(III)-(Oxyhydr)oxide Reduction and Secondary Mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Madhavi [Rutgers Univ., New Brunswick, NJ (United States); Lin, Chu-Ching [Rutgers Univ., New Brunswick, NJ (United States); Kukkadapu, Ravi K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Engelhard, Mark H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhao, Xiuhong [Rutgers Univ., New Brunswick, NJ (United States); Wang, Yangping [Rutgers Univ., New Brunswick, NJ (United States); Barkay, Tamar [Rutgers Univ., New Brunswick, NJ (United States); Yee, Nathan [Rutgers Univ., New Brunswick, NJ (United States)

    2013-07-09

    In this study, we cultivated from subsurface sediments an anaerobic Clostridia 25 consortium that was composed of a fermentative Fe-reducer Clostridium species (designated as 26 strain FGH) and a novel sulfate-reducing bacterium belonging to the Clostridia family 27 Vellionellaceae (designated as strain RU4). In pure culture, Clostridium sp. strain FGH mediated 28 the reductive dissolution/transformation of iron oxides during growth on peptone. When 29 Clostridium sp. FGH was grown with strain RU4 on peptone, the rates of iron oxide reduction 30 were significantly higher. Iron reduction by the consortium was mediated by multiple 31 mechanisms, including biotic reduction by Clostridium sp. FGH and biotic/abiotic reactions 32 involving biogenic sulfide by strain RU4. The Clostridium sp. FGH produced hydrogen during 33 fermentation, and the presence of hydrogen inhibited growth and iron reduction activity. The 34 sulfate-reducing partner strain RU4 was stimulated by the presence of H2 gas and generated 35 reactive sulfide which promoted the chemical reduction of the iron oxides. Characterization of 36 Fe(II) mineral products showed the formation of magnetite during ferrihydrite reduction, and 37 the precipitation of iron sulfides during goethite and hematite reduction. The results suggest an 38 important pathway for iron reduction and secondary mineralization by fermentative sulfate-39 reducing microbial consortia is through syntrophy-driven biotic/abiotic reactions with biogenic 40 sulfide.

  5. In situ reduction of as-prepared γ-Iron Oxide Nanoparticles

    DEFF Research Database (Denmark)

    Garbus, Pelle Gorm; Ahlburg, Jakob; Christensen, Mogens

    .L., et al., Size and Size Distribution Control of γ-Fe2O3 Nanocrystallites: An in Situ Study. Crystal Growth & Design, 2014. 14(3): p. 1307-1313.3.Bondesgaard, M., et al., Guide to by-products formed in organic solvents under solvothermal conditions. The Journal of Supercritical Fluids, 2016. 113: p. 166...... behind the structural development [1, 2] adds to the fundamental understanding of materials’ formation and can lead to new synthesis pathways. In this study, iron oxide (γ-Fe2O3) particles were heated to 400°C under a flow of H2/Ar mixture, while the process was followed by in situ synchrotron powder X......-iron oxide Fe2O3. The reduction of maghemite to body centered cubic (BCC) iron does not go through a detectable intermediate state.1.Jensen, K.M., et al., Mechanisms for iron oxide formation under hydrothermal conditions: an in situ total scattering study. ACS nano, 2014. 8(10): p. 10704-10714.2.Andersen, H...

  6. Size dependent microbial oxidation and reduction of magnetite nano- and micro-particles

    Science.gov (United States)

    Byrne, James M.; van der Laan, Gerrit; Figueroa, Adriana I.; Qafoku, Odeta; Wang, Chongmin; Pearce, Carolyn I.; Jackson, Michael; Feinberg, Joshua; Rosso, Kevin M.; Kappler, Andreas

    2016-08-01

    The ability for magnetite to act as a recyclable electron donor and acceptor for Fe-metabolizing bacteria has recently been shown. However, it remains poorly understood whether microbe-mineral interfacial electron transfer processes are limited by the redox capacity of the magnetite surface or that of whole particles. Here we examine this issue for the phototrophic Fe(II)-oxidizing bacteria Rhodopseudomonas palustris TIE-1 and the Fe(III)-reducing bacteria Geobacter sulfurreducens, comparing magnetite nanoparticles (d ≈ 12 nm) against microparticles (d ≈ 100-200 nm). By integrating surface-sensitive and bulk-sensitive measurement techniques we observed a particle surface that was enriched in Fe(II) with respect to a more oxidized core. This enables microbial Fe(II) oxidation to occur relatively easily at the surface of the mineral suggesting that the electron transfer is dependent upon particle size. However, microbial Fe(III) reduction proceeds via conduction of electrons into the particle interior, i.e. it can be considered as more of a bulk electron transfer process that is independent of particle size. The finding has potential implications on the ability of magnetite to be used for long range electron transport in soils and sediments.

  7. Oxidation state of chromium associated with cell surfaces of Shewanella oneidensis during chromate reduction

    Energy Technology Data Exchange (ETDEWEB)

    Neal, Andrew L.; Lowe, Kristine; Daulton, Tyrone L.; Jones-Meehan, Joanne; Little, Brenda J

    2002-12-30

    Employing electron energy loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS), we demonstrate that in both aerobic and anaerobic culture Shewanella oneidensis cells are capable of chromate reduction. No Cr(VI) or Cr(V) species were identified at the cell surfaces in Cr 2p{sub 3/}ore photoelectron spectra. More chromium was associated with cell surfaces recovered from anaerobic medium than aerobic. Multiplet-splitting models derived for Cr(III) and Cr(IV) were employed to determine contributions from each ion to Cr 2p{sub 3/2} photopeaks collected from the various cell treatments. Whilst in all cases Cr(III) was the major ion associated with cell surfaces, a significant contribution was identified due to Cr(IV) in anaerobically grown cells. The Cr(IV) contribution was far less when cells were grown aerobically. Moreover, when anaerobically grown cells were exposed to oxygen very little re-oxidation of Cr-precipitates occurred, the precipitates were again identified as a mixture of Cr(III) and Cr(IV). A positive relationship was observed between amounts of chromium and phosphorous associated with cell surfaces resulting from the various treatments, suggesting the precipitates included Cr(III)-phosphate. The fact that Cr(IV) remained associated with precipitates following re-oxidation suggests that under anaerobic conditions the intermediate ion is afforded sufficient stability to be incorporated within the precipitate matrix and thus conferred a degree of protection from oxidation.

  8. Myoglobin immobilization on electrodeposited nanometer-scale nickel oxide particles and direct voltammetry.

    Science.gov (United States)

    Moghaddam, Abdolmajid Bayandori; Ganjali, Mohammad Reza; Dinarvand, Rassoul; Ahadi, Sara; Saboury, Ali Akbar

    2008-04-01

    Prosperity of information on the reactions of redox-active sites in proteins can be attained by voltammetric studies in which the protein sample is located on a suitable surface. This work reports the presentation of myoglobin/nickel oxide nanoparticles/glassy carbon (Mb/NiO NPs/GC) electrode, ready by electrochemical deposition of the NiO NPs on glassy carbon electrode and myoglobin immobilization on their surfaces by the potential cycling method. Images of electrodeposited NiO NPs on the surface of glassy carbon electrode were obtained by scanning electron microscopy (SEM) and atomic force microscopy (AFM). A pair of well-defined redox peaks for Mb(Fe(III)-Fe(II)) was obtained at the prepared electrode by direct electron transfer between the protein and nanoparticles. Electrochemical parameters of immobilized myoglobin such as formal potential (E(0')), charge transfer coefficient (alpha) and apparent heterogeneous electron transfer rate constant (k(s)) were estimated by cyclic voltammetry and nonlinear regression analysis. Biocatalytic activity was exemplified at the prepared electrode for reduction of hydrogen peroxide.

  9. Aggregate-scale heterogeneity in iron (hydr)oxide reductive transformations

    Energy Technology Data Exchange (ETDEWEB)

    Tufano, K.J.; Benner, S.G.; Mayer, K.U.; Marcus, M.A.; Nico, P.S.; Fendorf, S.

    2009-06-15

    There is growing awareness of the complexity of potential reaction pathways and the associated solid-phase transformations during the reduction of Fe (hydr)oxides, especially ferrihydrite. An important observation in static and advective-dominated systems is that microbially produced Fe(II) accelerates Ostwald ripening of ferrihydrite, thus promoting the formation of thermodynamically more stable ferric phases (lepidocrocite and goethite) and, at higher Fe(II) surface loadings, the precipitation of magnetite; high Fe(II) levels can also lead to green rust formation, and with high carbonate levels siderite may also be formed. This study expands this emerging conceptual model to a diffusion-dominated system that mimics an idealized micropore of a ferrihydrite-coated soil aggregate undergoing reduction. Using a novel diffusion cell, coupled with micro-x-ray fluorescence and absorption spectroscopies, we determined that diffusion-controlled gradients in Fe{sup 2+}{sub (aq)} result in a complex array of spatially distributed secondary mineral phases. At the diffusive pore entrance, where Fe{sup 2+} concentrations are highest, green rust and magnetite are the dominant secondary Fe (hydr)oxides (30 mol% Fe each). At intermediate distances from the inlet, green rust is not observed and the proportion of magnetite decreases from approximately 30 to <10%. Across this same transect, the proportion of goethite increases from undetectable up to >50%. At greater distances from the advective-diffusive boundary, goethite is the dominant phase, comprising between 40 and 95% of the Fe. In the presence of magnetite, lepidocrocite forms as a transient-intermediate phase during ferrihydrite-to-goethite conversion; in the absence of magnetite, conversion to goethite is more limited. These experimental observations, coupled with results of reactive transport modeling, confirm the conceptual model and illustrate the potential importance of diffusion-generated concentration gradients in

  10. Magnetic oxide nanowires with strain-controlled uniaxial magnetic anisotropy direction

    NARCIS (Netherlands)

    Mathews, M.; Jansen, R.; Rijnders, G.; Lodder, J.C.; Blank, D.H.A.

    2009-01-01

    While magnetic nanowires generally have a preferential magnetization direction along the wire axis to minimize magnetostatic energy, it is shown here for epitaxial magnetic oxide nanowires that substrate-induced strain can be used to tailor the magnetic easy axis in any direction. La0.67Sr0.33MnO3 (

  11. Extended structure design with simple molybdenum oxide building blocks and urea as a directing agent

    NARCIS (Netherlands)

    Veen, S.J.; Roy, S.; Filinchuk, Y.; Chernyshov, D.; Petukhov, A.V.; Versluijs-Helder, M.; Broersma, A.; Soulimani, F.; Visser, T.; Kegel, W.K.

    2008-01-01

    We report here a simple one-pot directed synthesis of an oxomolybdate urea composite in which elementary molybdenum oxide building blocks are linked together with the aid of urea. This type of directed material design resulted in large rod-like crystals of an inorganic-organic hybrid extended struct

  12. Phosphorus and Nitrogen Dual Doped and Simultaneously Reduced Graphene Oxide with High Surface Area as Efficient Metal-Free Electrocatalyst for Oxygen Reduction

    Directory of Open Access Journals (Sweden)

    Xiaochang Qiao

    2015-06-01

    Full Text Available A P, N dual doped reduced graphene oxide (PN-rGO catalyst with high surface area (376.20 m2·g−1, relatively high P-doping level (1.02 at. % and a trace amount of N (0.35 at. % was successfully prepared using a one-step method by directly pyrolyzing a homogenous mixture of graphite oxide (GO and diammonium hydrogen phosphate ((NH42HPO4 in an argon atmosphere, during which the thermal expansion, deoxidization of GO and P, N co-doping were realized simultaneously. The catalyst exhibited enhanced catalytic performances for oxygen reduction reaction (ORR via a dominated four-electron reduction pathway, as well as superior long-term stability, better tolerance to methanol crossover than that of commercial Pt/C catalyst in an alkaline solution.

  13. Oxidation Process of H 2 O /UV for COD Reduction of Wastewater from Soybean Tofu Production

    Directory of Open Access Journals (Sweden)

    Komala Pontas

    2015-12-01

    Full Text Available Chemical Oxygen Demand (COD reduction of wastewater from soybean tofu production was studied by conducting advanced oxidation process (AOP using hydrogen peroxide with UV radiation catalysts in a closed cylindrical glass reactor. The hydroxyl radical (*OH concentration from H2O decomposition was modeled, and exponential trends were found for the *OH concentration over radiation time and operation temperature. As a result, it was found that the maximal *OH concentration was 0.209 mol L-12 at 240 minutes and 50 °C. The *OH concentration exponentially increased following rise in operation temperature. The H2O /UV AOP application reduced COD concentration to approximately 42.41% from 10,545 to 6,073.2 mol L-12 at 240 minutes and 50 °C. In addition, the pseudo second order kinetics is a reliable model to present the COD reduction kinetics with the correlation coefficient R in the range of 95.9 to 99.4%. The kinetics constant increased with rise in operation temperature, and it was approximately 2.30E-07, 2.590E-07, and 3.03E-07 L mg-1 min-1 for 30, 40, and 50 °C, respectively. The activation energy of COD reduction obtained was approximately 0.0138 J mol-1.

  14. A kinetic study of copper(II) oxide powder reduction with hydrogen, based on thermogravimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jelic, Dijana [Faculty of Medicine, Departmet of Pharmacy - Chair of Physical Chemistry, University of Banja Luka, Banja Luka, Bosnia and Herzegovina (Bosnia and Herzegowina); Tomic-Tucakovic, Biljana [Institute of General and Physical Chemistry, Studentski trg 12, 11158 Belgrade (Serbia); Mentus, Slavko, E-mail: slavko@ffh.bg.ac.rs [University of Belgrade, Faculty of Physical Chemistry, Studentski trg 12, 11185 Belgrade (Serbia)

    2011-07-10

    Highlights: {yields} The reduction of CuO by hydrogen was studied by thermogravimetry. {yields} The particle size of the samples varied inside the submicron range. {yields} The experimental data were fitted by means of a nucleation-growth model. {yields} The particle size influenced the kinetic parameters but not the reaction model. - Abstract: The reduction of powdery copper(II) oxide was carried out in a stream of gaseous mixture 25% H{sub 2} + Ar, and followed by thermogravimetry. The two samples of different history were studied: the commercial one, and that synthesized by citrate gel combustion method. The characterization of the starting materials, based on X-ray diffractometry and scanning electron microscopy, indicated equal crystal structure, but different particle size and morphology. The particle size and shape of the metallic particles obtained upon the reduction were observed by means of electron microscope. By a nonlinear regression analysis by means of a software Kinetics05, the experimental data were fitted with the nucleation-growth kinetic model, and the corresponding kinetic parameters were determined.

  15. Reduction of Cogging Torque in Dual Rotor Permanent Magnet Generator for Direct Coupled Wind Energy Systems

    Directory of Open Access Journals (Sweden)

    Sivachandran Paulsamy

    2014-01-01

    Full Text Available In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG for direct coupled stand alone wind energy systems (SAWES. Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  16. Reduction of cogging torque in dual rotor permanent magnet generator for direct coupled wind energy systems.

    Science.gov (United States)

    Paulsamy, Sivachandran

    2014-01-01

    In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  17. Shift from coke to coal using direct reduction method and challenges

    Energy Technology Data Exchange (ETDEWEB)

    Okonkwo Paul Chukwuleke; Jiu-ju Cai; Sam Chukwujekwu; Song Xiao [Deakin University, Waurn Ponds, Vic. (Australia)

    2009-03-15

    Ironmaking involves the separation of iron ores. It not only represents the first step in steelmaking but also is the most capital-intensive and energy-intensive process in the production of steel. The main route for producing iron for steelmaking is to use the blast furnace, which uses metallurgical coke as the reductant. Concerns over the limited resources, the high cost of coking coals, and the environmental impacts of coking and sinter plants have driven steelmakers to develop alternative ironmaking processes that can use non-coking coals to reduce iron ores directly. Since the efficiency and productivity of modern large capacity blast furnaces will be difficult to surpass, blast furnaces will continue to retain their predominant position as the foremost ironmaking process for some time to come. The alternative ironmaking processes are therefore expected to play an increasingly significant role in the iron and steel industry, especially in meeting the needs of small-sized local and regional markets. It is likely that the importance of direct reduced iron (DRI) and hot metal as sources of virgin iron will continue to increase, especially in the developing countries where steelmaking is, and will be, primarily based on electric arc furnace (EAF) minimills. Consequently, the challenges that are faced by the new technology have to be embraced.

  18. DNA-directed growth of Pd nanocrystals on carbon nanotubes towards efficient oxygen reduction reactions.

    Science.gov (United States)

    Zhang, Lian Ying; Guo, Chun Xian; Cui, Zhiming; Guo, Jun; Dong, Zhili; Li, Chang Ming

    2012-12-03

    Unique DNA-promoted Pd nanocrystals on carbon nanotubes (Pd/DNA-CNTs) are synthesized for the first time, in which through its regularly arranged PO(4)(3-) groups on the sugar-phosphate backbone, DNA directs the growth of ultrasmall Pd nanocrytals with an average size of 3.4 nm uniformly distributed on CNTs. The Pd/DNA-CNT catalyst shows much more efficient electrocatalytic activity towards oxygen reduction reaction (ORR) with a much more positive onset potential, higher catalytic current density and better stability than other Pd-based catalysts including Pd nanocrystals on carbon nanotubes (Pd/CNTs) without the use of DNA and commercial Pd/C catalyst. In addition, the Pd/DNA-CNTs catalyst provides high methanol tolerance. The high electrocatalytic performance is mainly contributed by the ultrasmall Pd nanocrystal particles grown directed by DNA to enhance the mass transport rate and to improve the utilization of the Pd catalyst. This work may demonstrate a universal approach to fabricate other superior metal nanocrystal catalysts with DNA promotion for broad applications in energy systems and sensing devices.

  19. Reduction of the Influence of Laser Beam Directional Dithering in a Laser Triangulation Displacement Probe.

    Science.gov (United States)

    Yang, Hongwei; Tao, Wei; Zhang, Zhengqi; Zhao, Siwei; Yin, Xiaoqia; Zhao, Hui

    2017-05-15

    Directional dithering of a laser beam potentially limits the detection accuracy of a laser triangulation displacement probe. A theoretical analysis indicates that the measurement accuracy will linearly decrease as the laser dithering angle increases. To suppress laser dithering, a scheme for reduction of the influence of laser beam directional dithering in a laser triangulation displacement probe, which consists of a collimated red laser, a laser beam pointing control setup, a receiver lens, and a charge-coupled device, is proposed in this paper. The laser beam pointing control setup is inserted into the source laser beam and the measured object and can separate the source laser beam into two symmetrical laser beams. Hence, at the angle at which the source laser beam dithers, the positional averages of the two laser spots are equal and opposite. Moreover, a virtual linear function method is used to maintain a stable average of the positions of the two spots on the imaging side. Experimental results indicate that with laser beam pointing control, the estimated standard deviation of the fitting error decreases from 0.3531 mm to 0.0100 mm , the repeatability accuracy can be lowered from ±7 mm to ±5 μ m , and the nonlinear error can be reduced from ±6 % FS (full scale) to ±0.16 % FS.

  20. Evaluation of Radiation Dose Reduction during CT Scans Using Oxide Bismuth and Nano-Barium Sulfate Shields

    CERN Document Server

    Seoung, Youl-Hun

    2015-01-01

    The purpose of the present study was to evaluate radiation dose reduction and image quality during CT scanning by using a new dose reduction fiber sheet (DRFS) with commercially available bismuth shields. These DRFS were composed of nano-barium sulfate (BaSO4), filling the gaps left by the large oxide bismuth (Bi2O3) particle sizes. The radiation dose was measured five times at directionss of 12 o'clock from the center of the polymethyl methacrylate (PMMA) head phantom to calculate an average value using a CT ionization chamber. The image quality measured CT transverse images of the PMMA head phantom depending on X-ray tube voltages and the type of shielding. Two regions of interest in CT transverse images were chosen from the right and left areas under the surface of the PMMA head phantom and from ion chamber holes located at directions of 12 o'clock from the center of the PMMA head phantom. The results of this study showed that the new DRFS shields could reduce dosages to 15.61%, 23.05%, and 22.71% more in ...

  1. Potentiometric determination of plutonium by argentic oxidation, ferrous reduction and dichromate titration.

    Science.gov (United States)

    Drummond, J L; Grant, R A

    1966-03-01

    A simple and rapid method is described for the routine determination of plutonium with a coefficient of variation of better than 0.2%. It is directly applicable to nitrate solutions containing a large amount of uranium; moderate amounts of iron, molybdenum, fluoride and phosphate do not interfere. Chromium, cerium and manganese interfere quantitatively, and the procedure may also prove convenient for the determination of these elements. The plutonium is oxidised to the sexivalent state with argentic oxide in nitric acid solution, and the excess of oxidant is destroyed by reaction with sulphamic acid. A weighed small excess of iron(II) solution is then added, and the excess is titrated potentiometrically with standard potassium dichromate solution using polarised gold indicator electrodes. The whole determination is performed in one vessel at room temperature, and takes about 20 min.

  2. Ruthenium nanoparticles for oxygen reduction and/or hydrogen oxidation, prepared by pyrolysis in a reducing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Altamirano-Gutierrez, A.; Villagran-Naredo, J.L.A.; Jimenez-Sandoval, O. [Inst. Politecnico Nacional (Mexico). Centro de Investigacion y de Estudios Avanzados; Hernandez-Castellanos, R. [Centro de Investigacion y Desarrollo Technologic en Electroquimica (Mexico)

    2006-07-01

    An investigation of the synthesis, structural and electrochemical characterization of ruthenium-based materials prepared by pyrolysis was presented. Ru{sub 3}(CO){sub 12} materials were pyrolized in a hydrogen atmosphere at 80, 140, 360 and 460 degrees C. The materials were then characterized using Fourier Transform Infrared (FTIR) spectroscopy; X-ray diffraction (XRD) and scanning electron microscopy (SEM). Oxygen reduction reactions (ORR) and hydrogen oxidation reactions (HOR) were evaluated through the use of rotating disk electrode measurements in a 0.5 M hydrogen peroxide (H{sub 2}SO{sub 4}) electrolyte at room temperature. Results of the investigation indicated that the Ru{sub 3}(CO){sub 12} precursor was completely decarbonylated in H{sub 2} at 140 degrees C. Carbonyl group bands were observed when the materials were prepared at 80 degrees C due to the formation of an inactive Ru cluster resulting from a structural rearrangement of the cluster. Polarization curves indicated that the materials prepared at 140 degrees C were able to perform the ORR and HOR in an acid medium similar to the medium present in proton exchange (PE) fuel cells. The electrokinetic parameters indicated that the exchange current densities were of the same order as platinum (Pt) current densities, and that the ORR occurred via 4 electrons due to the direct formation of water. Tafel slope values for the HOR suggested that the mechanism of the reaction was related to Herovsky/Volmer types. It was concluded that the use of a reductive atmosphere in the preparation process of ruthenium-based materials prevents the formation of undesirable ruthenium oxides. The nano-sized materials prepared during the experiment did not exhibit loss of their catalytic properties after being exposed to air for several weeks. 4 refs., 2 figs.

  3. Generation process of FeS and its inhibition mechanism on iron mineral reduction in selective direct reduction of laterite nickel ore

    Institute of Scientific and Technical Information of China (English)

    Zhi-guo Liu; Ti-chang Sun; Xiao-ping Wang; En-xia Gao

    2015-01-01

    Numerous studies have demonstrated that Na2SO4 can significantly inhibit the reduction of iron oxide in the selective reduction process of laterite nickel ore. FeS generated in the process plays an important role in selective reduction, but the generation process of FeS and its inhibition mechanism on iron reduction are not clear. To figure this out, X-ray diffraction and scanning electron microscopy analyses were conducted to study the roasted ore. The results show that when Na2SO4 is added in the roasting, the FeO content in the roasted ore in-creases accompanied by the emergence of FeS phase. Further analysis indicates that Na2S formed by the reaction of Na2SO4 with CO reacts with SiO2 at the FeO surface to generate FeS and Na2Si2O5. As a result, a thin film forms on the surface of FeO, hindering the contact be-tween reducing gas and FeO. Therefore, the reduction of iron is depressed, and the FeO content in the roasted ore increases.

  4. Detailed Multi-dimensional Modeling of Direct Internal Reforming Solid Oxide Fuel Cells.

    Science.gov (United States)

    Tseronis, K; Fragkopoulos, I S; Bonis, I; Theodoropoulos, C

    2016-06-01

    Fuel flexibility is a significant advantage of solid oxide fuel cells (SOFCs) and can be attributed to their high operating temperature. Here we consider a direct internal reforming solid oxide fuel cell setup in which a separate fuel reformer is not required. We construct a multidimensional, detailed model of a planar solid oxide fuel cell, where mass transport in the fuel channel is modeled using the Stefan-Maxwell model, whereas the mass transport within the porous electrodes is simulated using the Dusty-Gas model. The resulting highly nonlinear model is built into COMSOL Multiphysics, a commercial computational fluid dynamics software, and is validated against experimental data from the literature. A number of parametric studies is performed to obtain insights on the direct internal reforming solid oxide fuel cell system behavior and efficiency, to aid the design procedure. It is shown that internal reforming results in temperature drop close to the inlet and that the direct internal reforming solid oxide fuel cell performance can be enhanced by increasing the operating temperature. It is also observed that decreases in the inlet temperature result in smoother temperature profiles and in the formation of reduced thermal gradients. Furthermore, the direct internal reforming solid oxide fuel cell performance was found to be affected by the thickness of the electrochemically-active anode catalyst layer, although not always substantially, due to the counter-balancing behavior of the activation and ohmic overpotentials.

  5. Direct Growth of Crystalline Tungsten Oxide Nanorod Arrays by a Hydrothermal Process and Their Electrochromic Properties

    Science.gov (United States)

    Lu, Chih-Hao; Hon, Min Hsiung; Leu, Ing-Chi

    2016-12-01

    Transparent crystalline tungsten oxide nanorod arrays for use as an electrochromic layer have been directly prepared on fluorine-doped tin oxide-coated glass via a facile tungsten film-assisted hydrothermal process using aqueous tungsten hexachloride solution. X-ray diffraction analysis and field-emission scanning electron microscopy were used to characterize the phase and morphology of the grown nanostructures. Arrays of tungsten oxide nanorods with diameter of ˜22 nm and length of ˜240 nm were obtained at 200°C after 8 h of hydrothermal reaction. We propose a growth mechanism for the deposition of the monoclinic tungsten oxide phase in the hydrothermal environment. The tungsten film was first oxidized to tungsten oxide to provide seed sites for crystal growth and address the poor connection between the growing tungsten oxide and substrate. Aligned tungsten oxide nanorod arrays can be grown by a W thin film-assisted heterogeneous nucleation process with NaCl as a structure-directing agent. The fabricated electrochromic device demonstrated optical modulation (coloration/bleaching) at 632.8 nm of ˜41.2% after applying a low voltage of 0.1 V for 10 s, indicating the potential of such nanorod array films for use in energy-saving smart windows.

  6. Direct Growth of Crystalline Tungsten Oxide Nanorod Arrays by a Hydrothermal Process and Their Electrochromic Properties

    Science.gov (United States)

    Lu, Chih-Hao; Hon, Min Hsiung; Leu, Ing-Chi

    2017-04-01

    Transparent crystalline tungsten oxide nanorod arrays for use as an electrochromic layer have been directly prepared on fluorine-doped tin oxide-coated glass via a facile tungsten film-assisted hydrothermal process using aqueous tungsten hexachloride solution. X-ray diffraction analysis and field-emission scanning electron microscopy were used to characterize the phase and morphology of the grown nanostructures. Arrays of tungsten oxide nanorods with diameter of ˜22 nm and length of ˜240 nm were obtained at 200°C after 8 h of hydrothermal reaction. We propose a growth mechanism for the deposition of the monoclinic tungsten oxide phase in the hydrothermal environment. The tungsten film was first oxidized to tungsten oxide to provide seed sites for crystal growth and address the poor connection between the growing tungsten oxide and substrate. Aligned tungsten oxide nanorod arrays can be grown by a W thin film-assisted heterogeneous nucleation process with NaCl as a structure-directing agent. The fabricated electrochromic device demonstrated optical modulation (coloration/bleaching) at 632.8 nm of ˜41.2% after applying a low voltage of 0.1 V for 10 s, indicating the potential of such nanorod array films for use in energy-saving smart windows.

  7. Microbial Fe(III) Oxide Reduction in Chocolate Pots Hot Springs, Yellowstone National Park

    Science.gov (United States)

    Fortney, N. W.; Roden, E. E.; Boyd, E. S.; Converse, B. J.

    2014-12-01

    Previous work on dissimilatory iron reduction (DIR) in Yellowstone National Park (YNP) has focused on high temperature, low pH environments where soluble Fe(III) is utilized as an electron acceptor for respiration. Much less attention has been paid to DIR in lower temperature, circumneutral pH environments, where solid phase Fe(III) oxides are the dominant forms of Fe(III). This study explored the potential for DIR in the warm (ca. 40-50°C), circumneutral pH Chocolate Pots hot springs (CP) in YNP. Most probable number (MPN) enumerations and enrichment culture studies confirmed the presence of endogenous microbial communities that reduced native CP Fe(III) oxides. Enrichment cultures demonstrated sustained DIR coupled to acetate and lactate oxidation through repeated transfers over ca. 450 days. Pyrosequencing of 16S rRNA genes indicated that the dominant organisms in the enrichments were closely affiliated with the well known Fe(III) reducer Geobacter metallireducens. Additional taxa included relatives of sulfate reducing bacterial genera Desulfohalobium and Thermodesulfovibrio; however, amendment of enrichments with molybdate, an inhibitor of sulfate reduction, suggested that sulfate reduction was not a primary metabolic pathway involved in DIR in the cultures. A metagenomic analysis of enrichment cultures is underway in anticipation of identifying genes involved in DIR in the less well-characterized dominant organisms. Current studies are aimed at interrogating the in situ microbial community at CP. Core samples were collected along the flow path (Fig. 1) and subdivided into 1 cm depth intervals for geochemical and microbiological analysis. The presence of significant quantities of Fe(II) in the solids indicated that DIR is active in situ. A parallel study investigated in vitro microbial DIR in sediments collected from three of the coring sites. DNA was extracted from samples from both studies for 16S rRNA gene and metagenomic sequencing in order to obtain a

  8. Influences of hydrogen-enriched atmosphere under coke oven gas injection on reduction swelling behaviors of oxidized pellet

    Institute of Scientific and Technical Information of China (English)

    龙红明; 王宏涛; 狄瞻霞; 春铁军; 柳政根

    2016-01-01

    It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concentration in N2−CO−H2 atmosphere with unchanged CO content on reduction swelling behaviors of oxidized pellet at 1173 K were studied, to clarify the mechanism of hydrogen-enriched reduction and exclude the influences of CO. Then, the reduction swelling behaviors of oxidized pellet at 1173 K in actual atmosphere under coke oven gas (COG) injection, got from the simulation results of multi-fluid blast furnace model, were investigated. The results show that with the concentration of hydrogen increasing in N2−CO−H2 gas from 2% to 18%, the reduction swelling index of pellet decreases from 10.12% to 5.57% while the reduction ratio of pellet increases obviously from 39.85% to 69.58%. In addition, with COG injection rate increasing from 0 to 152.34 m3/t, the reduction swelling index of pellet decreases slightly from 10.71% to 9.54% while the reduction ratio of pellet is increased from 31.57% to 36.39%. The microstructures of pellet are transformed from the platy structure to the flocculent structure.

  9. Effect of L-ascorbic acid as additive for exhaust emission reduction in a direct injection diesel engine using mango seed methyl ester

    Directory of Open Access Journals (Sweden)

    Ramalingam Senthil

    2016-01-01

    Full Text Available In this present study the effect of L-ascorbic acid antioxidants additive for oxides of nitrogen emission reduction in a neat mango seed biodiesel fueled direct injection Diesel engine. The antioxidant additive L-ascorbic acid is tested on a Kirloskar-make four stroke water cooled single cylinder Diesel engine of 5.2 kW. There are four proportions of additive are used:1 ml, 2 ml, 3 ml, and 4 ml. Among the different additive proportion,4 ml concentration of L-ascorbic acid additive is optimal as oxides of nitrogen levels are substantially reduced up to 9% in the whole load range in comparison with neat biodiesel. However, hydrocarbon and carbonmonoxide emissions are found to have slightly increased by the addition of additive with biodiesel.

  10. Sustaining reactivity of Fe(0) for nitrate reduction via electron transfer between dissolved Fe(2+) and surface iron oxides.

    Science.gov (United States)

    Han, Luchao; yang, Li; Wang, Haibo; Hu, Xuexiang; Chen, Zhan; Hu, Chun

    2016-05-05

    The mechanism of the effects of Fe(2+)(aq) on the reduction of NO3(-) by Fe(0) was investigated. The effects of initial pH on the rate of NO3(-) reduction and the Fe(0) surface characteristics revealed Fe(2+)(aq) and the characteristics of minerals on the surface of Fe(0) played an important role in NO3(-) reduction. Both NO3(-) reduction and the decrease of Fe(2+)(aq) exhibited similar kinetics and were promoted by each other. This promotion was associated with the types of the surface iron oxides of Fe(0). Additionally, further reduction of NO3(-) produced more surface iron oxides, supplying more active sites for Fe(2+)(aq), resulting in more electron transfer between Fe(2+) and surface iron oxides and a higher reaction rate. Using the isotope specificity of (57)Fe Mossbauer spectroscopy, it was verified that the Fe(2+)(aq) was continuously converted into Fe(3+) oxides on the surface of Fe(0) and then converted into Fe3O4 via electron transfer between Fe(2+) and the pre-existing surface Fe(3+) oxides. Electrochemistry measurements confirmed that the spontaneous electron transfer between the Fe(2+) and structural Fe(3+) species accelerated the interfacial electron transfer between the Fe species and NO3(-). This study provides a new insight into the interaction between Fe species and contaminants and interface electron transfer. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Spectroscopic investigation and direct comparison of the reactivities of iron pyridyl oxidation catalysts

    Science.gov (United States)

    Song, Yang; Mayes, Howard G.; Queensen, Matthew J.; Bauer, Eike B.; Dupureur, Cynthia M.

    2017-03-01

    The growing interest in green chemistry has fueled attention to the development and characterization of effective iron complex oxidation catalysts. A number of iron complexes are known to catalyze the oxidation of organic substrates utilizing peroxides as the oxidant. Their development is complicated by a lack of direct comparison of the reactivities of the iron complexes. To begin to correlate reactivity with structural elements, we compare the reactivities of a series of iron pyridyl complexes toward a single dye substrate, malachite green (MG), for which colorless oxidation products are established. Complexes with tetradentate, nitrogen-based ligands with cis open coordination sites were found to be the most reactive. While some complexes reflect sensitivity to different peroxides, others are similarly reactive with either H2O2 or tBuOOH, which suggests some mechanistic distinctions. [Fe(S,S-PDP)(CH3CN)2](SbF6)2 and [Fe(OTf)2(tpa)] transition under the oxidative reaction conditions to a single intermediate at a rate that exceeds dye degradation (PDP = bis(pyridin-2-ylmethyl) bipyrrolidine; tpa = tris(2-pyridylmethyl)amine). For the less reactive [Fe(OTf)2(dpa)] (dpa = dipicolylamine), this reaction occurs on a timescale similar to that of MG oxidation. Thus, the spectroscopic method presented herein provides information about the efficiency and mechanism of iron catalyzed oxidation reactions as well as about potential oxidative catalyst decomposition and chemical changes of the catalyst before or during the oxidation reaction.

  12. Graphene oxide adsorption enhanced by in situ reduction with sodium hydrosulfite to remove acridine orange from aqueous solution.

    Science.gov (United States)

    Sun, Ling; Yu, Hongwen; Fugetsu, Bunshi

    2012-02-15

    Graphene oxide (GO) is a highly effective adsorbent, and its absorbing capability is further enhanced through its in situ reduction with sodium hydrosulfite as the reductant. Acridine orange is the selected target to eliminate with GO as the adsorbent. Under identical conditions, GO without the in situ reduction showed a maximum adsorption capacity of 1.4 g g(-1), and GO with the in situ reduction provided a maximum adsorption capacity of 3.3 g g(-1). Sodium hydrosulfite converts carbonyl groups on GO into hydroxyl groups, which function as the key sites for the adsorption enhancement.

  13. Formation of Fe(0-Nanoparticles via Reduction of Fe(II Compounds by Amino Acids and Their Subsequent Oxidation to Iron Oxides

    Directory of Open Access Journals (Sweden)

    K. Klačanová

    2013-01-01

    Full Text Available Iron nanoparticles were prepared by the reduction of central Fe(II ion in the coordination compounds with amino acid ligands. The anion of the amino acid used as a ligand acted as the reducing agent. Conditions for the reduction were very mild; the temperature did not exceed 52°C, and the optimum pH was between 9.5 and 9.7. The metal iron precipitated as a mirror on the flask or as a colloid in water. Identification of the product was carried out by measuring UV/VIS spectra of the iron nanoparticles in water. The iron nanoparticles were oxidized by oxygen yielding a mixture of iron oxides. Oxidation of Fe(0 to Fe(II took several seconds under air. The size and properties of iron oxide nanoparticles were studied by UV/VIS, TEM investigation, RTG diffractometry, Mössbauer spectroscopy, magnetometry, thermogravimetry, and GC/MS.

  14. Synthesis of Unsymmetric Ureas by Selenium-Catalyzed Oxidative-Reductive Carbonylation with CO

    Institute of Scientific and Technical Information of China (English)

    MEI Jian-Ting; LU Shi-Wei

    2003-01-01

    @@ Unsymmetric, substituted ureas that contain the peptide bond (NHCONH), many of which possess biological activities, are widely used as herbicides, agrochemicals and pharmaceuticals. [1,2] A series of unsymmetric ureascontaining substituted groups have been synthesized via selenium-catalyzed selective oxidative-reductive carbonylation of amines and nitro compounds with CO instead of phosgene in one-pot reaction. [3,4] These catalytic reactions are important from both synthetic and industrial points of view, because not only the reactions can be proceeded with high selectivity of higher than 99% towards desired unsymmetric ureas, but also there exists a phase-transfer process of the selenium catalyst in thereaction, so that the after-treatment of the catalysts and products from the reaction systems can be easily separated by simple phase separation.

  15. Characterization of Aniline Tetramer by MALDI TOF Mass Spectrometry upon Oxidative and Reductive Cycling

    Directory of Open Access Journals (Sweden)

    Rebecca L. Li

    2016-11-01

    Full Text Available By combining electrochemical experiments with mass spectrometric analysis, it is found that using short chain oligomers to improve the cycling stability of conducting polymers in supercapacitors is still problematic. Cycling tests via cyclic voltammetry over a potential window of 0 to 1.0 V or 0 to 1.2 V in a two-electrode device configuration resulted in solid-state electropolymerization and chain scission. Electropolymerization of the aniline tetramer to generate long chain oligomers is shown to be possible despite the suggested decrease in reactivity and increase in intermediate stability with longer oligomers. Because aniline oligomers are more stable towards reductive cycling when compared to oxidative cycling, future conducting polymer/oligomer-based pseudocapacitors should consider using an asymmetric electrode configuration.

  16. The Catalysis of NAD+ on Methanol Anode Oxidation Electrode for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping; PAN Mu; YUAN Run-zhang

    2004-01-01

    A tentative idea of developing a liquid-catalytic system on methanol anode oxidation was proposed by analyzing the characteristics of methanol anode oxidation in direct methanol fuel cell. The kinetics of methanol oxidation at a glassy carbon electrode in the presence of nicotinamide adenine dinucleotide (NAD+) was investigated. It is found that the current density of methanol oxidation increases greatly and the electrochemical reaction impedance reduces obviously in the presence of NAD+ compared with those in the absence of NAD+. The catalytic activity of NAD+ is sensitive to temperature. When the temperature preponderates over 45℃, NAD+ is out of function of catalysis for methanol oxidation, which is probably due to the denaturation of NAD+ at a relatively high temperature.

  17. Kidney-Specific Reduction of Oxidative Phosphorylation Genes Derived from Spontaneously Hypertensive Rat.

    Directory of Open Access Journals (Sweden)

    Jason A Collett

    Full Text Available Mitochondrial (Mt dysfunction contributes to the pathophysiology of renal function and promotes cardiovascular disease such as hypertension. We hypothesize that renal Mt-genes derived from female spontaneously hypertensive rats (SHR that exhibit hypertension have reduced expression specific to kidney cortex. After breeding a female Okamoto-Aoki SHR (SAP = 188mmHg with Brown Norway (BN males (SAP = 100 and 104 mmHg, hypertensive female progeny were backcrossed with founder BN for 5 consecutive generations in order to maintain the SHR mitochondrial genome in offspring that contain over increasing BN nuclear genome. Mt-protein coding genes (13 total and nuclear transcription factors mediating Mt-gene transcription were evaluated in kidney, heart and liver of normotensive (NT: n = 20 vs. hypertensive (HT: n = 20 BN/SHR-mtSHR using quantitative real-time PCR. Kidney cortex, but not liver or heart Mt-gene expression was decreased ~2-5 fold in 12 of 13 protein encoding genes of HT BN/SHR-mtSHR. Kidney cortex but not liver mRNA expression of the nuclear transcription factors Tfam, NRF1, NRF2 and Pgc1α were also decreased in HT BN/SHR-mtSHR. Kidney cortical tissue of HT BN/SHR-mtSHR exhibited lower cytochrome oxidase histochemical staining, indicating a reduction in renal oxidative phosphorylation but not in liver or heart. These results support the hypothesis that renal cortex of rats with SHR mitochondrial genome has specifically altered renal expression of genes encoding mitochondrial proteins. This kidney-specific coordinated reduction of mitochondrial and nuclear oxidative metabolism genes may be associated with heritable hypertension in SHR.

  18. High-performance Bi-stage process in reduction of graphene oxide for transparent conductive electrodes

    Science.gov (United States)

    Alahbakhshi, Masoud; Fallahi, Afsoon; Mohajerani, Ezeddin; Fathollahi, Mohammad-Reza; Taromi, Faramarz Afshar; Shahinpoor, Mohsen

    2017-02-01

    A novel and innovative approach to develop reduction of graphene oxide (GO) solution for fabrication of highly and truly transparent conductive electrode (TCE) has been presented. Thanks to outstanding mechanical and electronic properties of graphene which offer practical applications in synthesizing composites as well as fabricating various optoelectronic devices, in this study, conductive reduced graphene oxide (r-GO) thin films were prepared through sequential chemical and thermal reduction process of homogeneously dispersed GO solutions. The conductivity and transparency of r-GO thin film is regulated using hydroiodic acid (HI) as reducing agent following by vacuum thermal annealing. The prepared r-GO is characterized by XRD, AFM, UV-vis and Raman spectroscopy. the AFM topographic images reveal surface roughness almost ∼11 nm which became less than 2 nm for the 4 mg/mL solution. Moreover, XRD analysis and Raman spectra substantiate the interlayer spacing between rGO layers has been reduced dramatically and also electronic conjugation has been ameliorated after using HI chemical agent and 700 °C thermal annealing sequentially. Subsequently providing r-GO transparent electrode with decent and satisfactory transparency, acceptable conductivity and suitable work function, it has been exploited as the anode in organic light emitting diode (OLED). The maximum luminance efficiency and maximum power efficiency reached 4.2 cd/A and 0.83 lm/W, respectively. We believe that by optimizing the hole density, sheet resistance, transparency and surface morphology of the r-GO anodes, the device efficiencies can be remarkably increased further.

  19. Novel osmium-based electrocatalysts for oxygen reduction and hydrogen oxidation in acid conditions

    Energy Technology Data Exchange (ETDEWEB)

    Uribe-Godinez, J.; Borja-Arco, E.; Altamirano-Gutierrez, A.; Jimenez-Sandoval, O. [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional (Cinvestav), Unidad Queretaro, Apartado Postal 1-798, Queretaro, Qro. 76001 (Mexico); Castellanos, R.H. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-Queretaro, Av. Cerro Blanco No. 141, Col. Colinas del Cimatario, Queretaro, Qro. 76090 (Mexico)

    2008-03-01

    In this work, novel osmium electrocatalysts for oxygen reduction and hydrogen oxidation in 0.5 M H{sub 2}SO{sub 4}, have been developed. The syntheses were performed by thermolysis of Os{sub 3}(CO){sub 12} and Os{sub 3}(CO){sub 12}/Vulcan {sup registered}, in two reaction media, N{sub 2} (in the absence of solvents) and n-octane, in order to evaluate the effect of these parameters on the electrocatalytic activity of the new materials. In the solvent-free pathway, different reaction temperatures (in the 120-320 C range) and times (5, 7 and 10 h) were explored; the syntheses in n-octane were done at reflux temperature, for 30 and 72 h. The products were characterized structurally by FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy, and electrochemically by room temperature rotating disk electrode measurements, using cyclic and linear sweep voltammetry. Some materials prepared in both reaction media can efficiently perform the hydrogen oxidation and/or oxygen reduction reaction, i.e. those prepared by pyrolysis of Os{sub 3}(CO){sub 12}/Vulcan {sup registered} in N{sub 2}, at 180 C/7 h, 320 C/5 h, 320 C/7 h and 320 C/10 h, as well as the materials synthesized in n-octane (from both Os precursors); the latter, in addition, have the important property of being tolerant to carbon monoxide to some extent, in contrast to platinum, which is easily deactivated even by traces of CO. (author)

  20. Reduction of Nitrogen Oxides Emissions from a Coal-Fired Boiler Unit

    Directory of Open Access Journals (Sweden)

    Zhuikov Andrey V.

    2016-01-01

    Full Text Available During combustion of fossil fuels a large amount of harmful substances are discharged into the atmospheres of cities by industrial heating boiler houses. The most harmful substances among them are nitrogen oxides. The paper presents one of the most effective technological solutions for suppressing nitrogen oxides; it is arrangement of circulation process with additional mounting of the nozzle directed into the bottom of the ash hopper. When brown high-moisture coals are burnt in the medium power boilers, generally fuel nitrogen oxides are produced. It is possible to reduce their production by two ways: lowering the temperature in the core of the torch or decreasing the excess-air factor in the boiler furnace. Proposed solution includes the arrangement of burning process with additional nozzle installed in the lower part of the ash hopper. Air supply from these nozzles creates vortex involving large unburned fuel particles in multiple circulations. Thereby time of their staying in the combustion zone is prolonging. The findings describe the results of the proposed solution; and recommendations for the use of this technological method are given for other boilers.

  1. Interface-directed sol-gel:direct fabrication of the covalently attached ultraflat inorganic oxide pattern on functionalized plastics

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    For plastic electronics and optics,the fabrication of smooth,transparent and stable crack-free inorganic oxide films(and patterning) on flexible polymeric substrates with strong bonding strength and controllable thickness from nanometers to micrometers is a key but still remains a challenge.Among versatile inorganic oxides,silica oxide film as SiOx is especially important because this semiconductor material could provide crucial properties in devices or serve as a base layer for further multilayer construction.In this paper,we describe a new interface-directed sol-gel method to fabricate flexible high quality silicon oxide film onto commodity plastics.The resulting crack-free silica film has strong covalent bonding with polymer substrates,homogeneous morphology with ultralow roughness,highly optical transparency,tunable thickness from nm to μm,and easy patterning ability.Such fabrication strategy relies on a novel photocatalytic oxidation reaction by photosensitive ammonium persulfate(APS),which is able to fabricate highly reactive hydroxyl monolayer surface on inert polymeric substrates.This kind of hydroxylated surface could serve as nucleation and growth sites to initiate surface sol-gel process.As a result,well-defined SiOx film deposition(gelation) occurs,and patterned hydroxylation regions could be easily utilized to induce the formation of patterned oxide film arrays.Our strategy also excludes the requirements of clean room and vacuum devices so as to fulfill low-cost and fast fabrication demands.Two application examples from such high quality SiOx layer onto plastics are given but should not be limited within these.One is that oxygen permeation rate of SiOx deposited polymer film decreases 25 times than pristine polymer substrate,which is good for the potential packaging materials.The other one is that silanization monolayer,for example,3-aminopropyltriethoxysilane(APTES),could be successfully constructed onto silica layer through classical silanization

  2. Direct oxidation of methyl radicals in OCM process deduced from correlation of product selectivities

    Institute of Scientific and Technical Information of China (English)

    Zhiming Gao; Yuanyuan Ma

    2010-01-01

    Selectivity of hydrogen in reaction of oxidative coupling of methane(OCM)was evaluated over the MxOy-BaCO3(MxOy: La2O3,Sm2O3,MgO,CaO)catalysts.Correlation of product selectivities was thus discussed.From the correlation of product selectivities,it is revealed that the carbon oxides(CO and CO2)were most probably formed from the direct oxidation of methyl radicals under the conditions adopted in the present work.This is also in accordance with the OCM mechanism proposed in literature.

  3. EMISSION REDUCTION FROM A DIESEL ENGINE FUELED BY CERIUM OXIDE NANO-ADDITIVES USING SCR WITH DIFFERENT METAL OXIDES COATED CATALYTIC CONVERTER

    Directory of Open Access Journals (Sweden)

    B. JOTHI THIRUMAL

    2015-11-01

    Full Text Available This paper reports the results of experimental investigations on the influence of the addition of cerium oxide in nanoparticle form on the major physiochemical properties and the performance of diesel. The fuel is modified by dispersing the catalytic nanoparticle by ultrasonic agitation. The physiochemical properties of sole diesel fuel and modified fuel are tested with ASTM standard procedures. The effects of the additive nanoparticles on the individual fuel properties, the engine performance, and emissions are studied, and the dosing level of the additive is optimized. Cerium oxide acts as an oxygen-donating catalyst and provides oxygen for the oxidation of CO during combustion. The active energy of cerium oxide acts to burn off carbon deposits within the engine cylinder at the wall temperature and prevents the deposition of non-polar compounds on the cylinder wall which results in reduction in HC emission by 56.5%. Furthermore, a low-cost metal oxide coated SCR (selective catalyst reduction, using urea as a reducing agent, along with different types of CC (catalytic converter, has been implemented in the exhaust pipe to reduce NOx. It was observed that a reduction in NOx emission is 50–60%. The tests revealed that cerium oxide nanoparticles can be used as an additive in diesel to improve complete combustion of the fuel and reduce the exhaust emissions significantly.

  4. Reduction of nitric oxide with carbon monoxide on the Al-Mo(110) surface alloy

    Science.gov (United States)

    Grigorkina, G. S.; Tvauri, I. V.; Kaloeva, A. G.; Burdzieva, O. G.; Sekiba, D.; Ogura, S.; Fukutani, K.; Magkoev, T. T.

    2016-05-01

    Coadsorption and reaction of carbon monoxide (CO) and nitric oxide (NO) on Al-Mo(110) surface alloy have been studied by means of Auger electron, reflection-absorption infrared and temperature programmed desorption spectroscopies (AES, RAIRS, TPD), low energy electron diffraction (LEED) and work function measurements. The Al-Mo(110) surface alloy was obtained by thermal annealing at 800 K of aluminum film deposited on Mo(110) held at room temperature. Upon annealing Al penetrates the surface, most likely forming stoichiometric hexagonal surface monolayer of the compound Al2Mo. The NO and CO adsorb molecularly on this alloy surface at 200 K, unlike totally dissociative adsorption on bare Mo(110) and Al(111) film. Adsorption of CO on NO precovered Al-Mo(110) substrate dramatically affects the state of NO molecules, most probably displacing them to higher-coordinated sites with their simultaneous tilting to the surface plane. Heating to about room temperature (320 K) causes reduction of nitric oxide with carbon monoxide, yielding CO2, and substrate nitridation. This behavior can be associated with the surface reconstruction providing additional Al/Mo interface reaction sites and change of the d-band upon alloying.

  5. Degradation kinetics of peptide-coupled alginates prepared via the periodate oxidation reductive amination route.

    Science.gov (United States)

    Dalheim, Marianne Ø; Ulset, Ann-Sissel T; Jenssen, Ina Beate; Christensen, Bjørn E

    2017-02-10

    Biomaterials based on peptide-coupled alginates must provide both optimal biological environments and tuneable stability/degradation profiles. The present work investigates the degradation pattern and kinetics of peptide-coupled alginates prepared via the periodate oxidation reductive amination route. Alginates degrade slowly (non-enzymatically) under physiological conditions by acid-catalysed hydrolysis and alkali-catalysed β-elimination, both operating simultaneously but dominated by the latter. While periodate oxidation alone largely increases the rate of β-elimination, substitution restores the susceptibility towards β-elimination to that of the parent alginate. For acid hydrolysis the rate of depolymerization is proportional to the degree of substitution, being approximately one order of magnitude larger than the parent alginate, but still lower than for the corresponding materials with fully reduced dialdehydes. Results also suggest a composition-dependent preference for substitution at C2 or C3. These results demonstrate how the various chemistries introduced by the coupling provide useful means to tune the biodegradability profiles.

  6. Ordered PdCu-Based Nanoparticles as Bifunctional Oxygen-Reduction and Ethanol-Oxidation Electrocatalysts.

    Science.gov (United States)

    Jiang, Kezhu; Wang, Pengtang; Guo, Shaojun; Zhang, Xu; Shen, Xuan; Lu, Gang; Su, Dong; Huang, Xiaoqing

    2016-07-25

    The development of superior non-platinum electrocatalysts for enhancing the electrocatalytic activity and stability for the oxygen-reduction reaction (ORR) and liquid fuel oxidation reaction is very important for the commercialization of fuel cells, but still a great challenge. Herein, we demonstrate a new colloidal chemistry technique for making structurally ordered PdCu-based nanoparticles (NPs) with composition control from PdCu to PdCuNi and PtCuCo. Under the dual tuning on the composition and intermetallic phase, the ordered PdCuCo NPs exhibit better activity and much enhanced stability for ORR and ethanol-oxidation reaction (EOR) than those of disordered PdCuM NPs, the commercial Pt/C and Pd/C catalysts. The density functional theory (DFT) calculations reveal that the improved ORR activity on the PdCuM NPs stems from the catalytically active hollow sites arising from the ligand effect and the compressive strain on the Pd surface owing to the smaller atomic size of Cu, Co, and Ni. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Organometallic dimers: application to work-function reduction of conducting oxides.

    Science.gov (United States)

    Giordano, Anthony J; Pulvirenti, Federico; Khan, Talha M; Fuentes-Hernandez, Canek; Moudgil, Karttikay; Delcamp, Jared H; Kippelen, Bernard; Barlow, Stephen; Marder, Seth R

    2015-02-25

    The dimers of pentamethyliridocene and ruthenium pentamethylcyclopentadienyl mesitylene, (IrCp*Cp)2 and (RuCp*mes)2, respectively, are shown here to be effective solution-processable reagents for lowering the work functions of electrode materials; this approach is compared to the use of solution-deposited films of ethoxylated poly(ethylenimine) (PEIE). The work functions of indium tin oxide (ITO), zinc oxide, and gold electrodes can be reduced to 3.3-3.4 eV by immersion in a toluene solution of (IrCp*Cp)2; these values are similar to those that can be obtained by spin-coating a thin layer of PEIE onto the electrodes. The work-function reductions achieved using (IrCp*Cp)2 are primarily attributable to the interface dipoles associated with the formation of submonolayers of IrCp*Cp(+) cations on negatively charged substrates, which in turn result from redox reactions between the dimer and the electrode. The electrical properties of C60 diodes with dimer-modified ITO cathodes are similar to those of analogous devices with PEIE-modified ITO cathodes.

  8. Reductive dehalogenation of the trichloromethyl group of nitrapyrin by the ammonia-oxidizing bacterium Nitrosomonas europaea.

    Science.gov (United States)

    Vannelli, T; Hooper, A B

    1993-01-01

    Suspensions of Nitrosomonas europaea catalyzed the reductive dehalogenation of the commercial nitrification inhibitor nitrapyrin (2-chloro-6-trichloromethylpyridine). The product of the reaction was identified as 2-chloro-6-dichloromethylpyridine by its mass fragmentation and nuclear magnetic resonance spectra. A small amount of 2-chloro-6-dichloromethylpyridine accumulated during the conversion of nitrapyrin to 6-chloropicolinic acid in an aerated solution in the presence of ammonia (T. Vannelli and A.B. Hooper, Appl. Environ. Microbiol. 58:2321-2325, 1992). Nearly stoichiometric conversion of nitrapyrin to 2-chloro-6-dichloromethylpyridine occurred at very low oxygen concentrations and in the presence of hydrazine as a source of electrons. Under these conditions the turnover rate was 0.37 nmol of nitrapyrin per min per mg of protein. Two specific inhibitors of ammonia oxidation, acetylene and allylthiourea, inhibited the rate of the dehalogenation reaction by 80 and 84%, respectively. In the presence of D2O, all 2-chloro-6-dichloromethylpyridine produced in the reaction was deuterated at the methyl position. In an oxygenated solution and in the presence of ammonia or hydrazine, cells did not catalyze the oxidation of exogenously added 2-chloro-6-dichloromethylpyridine to 6-chloropicolinic acid. Thus, 2-chloro-6-dichloromethylpyridine is apparently not an intermediate in the aerobic production of 6-chloropicolinic acid from nitrapyrin. PMID:8285668

  9. Hydrazine reduction of transition metal oxides - In situ characterization using X-ray photoelectron spectroscopy

    Science.gov (United States)

    Littrell, D. M.; Tatarchuk, B. J.

    1986-01-01

    The transition metal oxides (TMOs) V2O5, FeO3, Co3O4, NiO, CuO, and ZnO were exposed to hydrazine at various pressures. The metallic surfaces were surveyed by in situ X-ray photoelectron spectroscopy to determine the irrelative rate of reduction by hydrazine. The most easily reducible oxide, CuO, could be reduced to the metallic state at room temperature and 10 to the -6th torr. The reaction is first order with respect to CuO, with an activation energy of about 35 kJ/mol. Two types of adsorption were seen to occur at 295 K: (1) a reversible component in which the measured N:Cu ratio increased to 0.60 at hydrazine pressures up to 0.5 torr, and (2) an irreversible component, with a N:Cu ratio of 0.28, which could not be removed by extended vacuum pumping. The results of this study are useful for the identification of TMO's that can be used as solid neatallizers of hydrazine spills, and for the preparation of metal surfaces for electroplating and evaporative thin-film coating.

  10. Influence of electrochemical reduction and oxidation processes on the decolourisation and degradation of C.I. Reactive Orange 4 solutions.

    Science.gov (United States)

    del Río, A I; Molina, J; Bonastre, J; Cases, F

    2009-06-01

    The electrochemical treatment of wastewaters from textile industry is a promising treatment technique for substances which are resistant to biodegradation. This paper presents the results of the electrochemical decolourisation and degradation of C.I. Reactive Orange 4 synthetic solutions (commercially known as Procion Orange MX2R). Electrolyses were carried out under galvanostatic conditions in a divided or undivided electrolytic cell. Therefore, oxidation, reduction or oxido-reduction experiences were tested. Ti/SnO(2)-Sb-Pt and stainless steel electrodes were used as anode and cathode, respectively. Degradation of the dye was followed by TOC, total nitrogen, COD and BOD(5) analyses. TOC removal after an oxidation process was higher than after oxido-reduction while COD removal after this last process was about 90%. Besides, the biodegradability of final samples after oxido-reduction process was studied and an improvement was observed. UV-Visible spectra revealed the presence of aromatic structures in solution when an electro-reduction was carried out while oxido-reduction process degraded both azo group and aromatic structures. HPLC analyses indicated the presence of a main intermediate after the reduction process with a chemical structure closely similar to 2-amine-1, 5-naphthalenedisulfonic acid. The lowest decolourisation rate corresponded to electrochemical oxidation. In these experiences a higher number of intermediates were generated as HPLC analysis demonstrated. The decolourisation process for the three electrochemical processes studied presented a pseudo-first order kinetics.

  11. Harmonic reduction of Direct Torque Control of six-phase induction motor.

    Science.gov (United States)

    Taheri, A

    2016-07-01

    In this paper, a new switching method in Direct Torque Control (DTC) of a six-phase induction machine for reduction of current harmonics is introduced. Selecting a suitable vector in each sampling period is an ordinal method in the ST-DTC drive of a six-phase induction machine. The six-phase induction machine has 64 voltage vectors and divided further into four groups. In the proposed DTC method, the suitable voltage vectors are selected from two vector groups. By a suitable selection of two vectors in each sampling period, the harmonic amplitude is decreased more, in and various comparison to that of the ST-DTC drive. The harmonics loss is greater reduced, while the electromechanical energy is decreased with switching loss showing a little increase. Spectrum analysis of the phase current in the standard and new switching table DTC of the six-phase induction machine and determination for the amplitude of each harmonics is proposed in this paper. The proposed method has a less sampling time in comparison to the ordinary method. The Harmonic analyses of the current in the low and high speed shows the performance of the presented method. The simplicity of the proposed method and its implementation without any extra hardware is other advantages of the proposed method. The simulation and experimental results show the preference of the proposed method.

  12. Multifunctional polymer-metal nanocomposites via direct chemical reduction by conjugated polymers.

    Science.gov (United States)

    Xu, Ping; Han, Xijiang; Zhang, Bin; Du, Yunchen; Wang, Hsing-Lin

    2014-03-07

    Noble metal nanoparticles (MNPs) have attracted continuous attention due to their promising applications in chemistry, physics, bioscience, medicine and materials science. As an alternative to conventional solution chemistry routes, MNPs can be directly synthesized through a conjugated polymer (CP) mediated technique utilizing the redox chemistry of CPs to chemically reduce the metal ions and modulate the size, morphology, and structure of the MNPs. The as-prepared multifunctional CP-MNP nanocomposites have shown application potentials as highly sensitive surface enhanced Raman spectroscopy (SERS) substrates, effective heterogeneous catalysts for organic synthesis and electrochemistry, and key components for electronic and sensing devices. In this tutorial review, we begin with a brief introduction to the chemical nature and redox properties of CPs that enable the spontaneous reduction of noble metal ions to form MNPs. We then focus on recent progress in control over the size, morphology and structure of MNPs during the conjugated polymer mediated syntheses of CP-MNP nanocomposites. Finally, we highlight the multifunctional CP-MNP nanocomposites toward their applications in sensing, catalysis, and electronic devices.

  13. Reduction of Iron Oxides: A Comparison Between Biotic and Abiotic Pathways

    Science.gov (United States)

    Guyodo, Y. J.; Ona-Nguema, G.; Bonville, P.; Lagroix, F.

    2009-12-01

    The occurrence of fine particles of magnetite in soils and sediments may, under favorable climatic and environmental conditions, be the result of iron reduction in pre-existing magnetic phases. Nonetheless, the conditions and pathways leading to magnetite formation, and the connection between the amount and type of magnetite particles (size distribution, shape, etc…) and past climatic conditions remains to be elucidated. One way to address this fundamental question is to perform controlled experiments using synthetic iron bearing minerals subjected to specific physical and bio-chemical conditions. At the meeting, we will present experiments performed on synthetic maghemite (γ-Fe2O3) and lepidocrocite (γ-FeOOH) samples. In a first series of experiments, iron- reducing bacteria Shewanella putrefaciens were used to produce magnetite (Fe3O4) nanoparticles, the starting iron oxides being used as electron acceptor. In a second set of experiments, the starting iron oxides were converted to magnetite by slow heating in CO/CO2 atmosphere. Subsequently, the resulting samples were subjected to slow heating in air, in order to induce aging and oxidation of the material. In our presentation, we will show key results of our experiments, including both magnetic (low-temperature, low-field and high-field magnetic measurements, Mossbaüer spectroscopy, etc.) and non-magnetic (XRD, HRTEM, etc.) characterizations. The different series of experiments conducted on these samples shall allow us to better constrain pathways of magnetite formation and alteration in the environment, including solid-state conversion, partial or total dissolution/precipitation, and particles aggregation.

  14. Protective effect of ascorbic acid in experimental gastric cancer:reduction of oxidative stress

    Institute of Scientific and Technical Information of China (English)

    Claudia P.M.S.Oliveira; Paulo Kassab; Fabio P.Lopasso; Heraldo P. Souza; Mariano Janiszewski; Francisco R. M. Laurindo; Kioshi Iriya; Antonio A.Laudanna

    2003-01-01

    AIM: Oxidative stress participates in the cell carcinogenesis by inducing DNA mutations. Our aim was to assess whether ascorbic acid, an antioxidant, could have a role in preventing ROS (Reactive Oxygen Species) generation in experimental gastric carcinoma in a rat model.METHODS: Experimental gastric cancer was induced in twelve Wistar male rats (weighting 250-350 g) by profound duodeno-gastric reflux throught split gastrojenunostomy. The rats were allocated to the following groups: Group Ⅰ (n=6)was the control; Group Ⅱ (n=6) which was mantained with daily intake of tape water with Vitamin C (30 mg/Kg). After 6 or 12 months, samples of gastric tumor or non tumor mucosa were taken from the anastomosis of both groups.Oxidative stress was measured by superoxide quantification through lucigenin-amplified chemiluminescence base and by staining with Nitrobluetetrazolium. The histopathologic confirmation of adenocarcinoma was made by eosinhemathoxilin method.RESULTS: The intestinal type of gastric adenocarcinoma was microscopically identified in all animals of group Ⅰwhereas only 3 rats of group Ⅱ showed an adenocarcinoma without macroscopic evidence of them. The cancers were located in the anastomosis in all cases. Basal luminescence from tumor gastric tissue generated 38.4±6.8 count per minute/mg/x106 (mean±SD) and 14.9±4.0 count per minute/mg/×106, respectively, in group Ⅰ and Ⅱ animals (P<0.05). The Nitrobluetetrazolium method showed intense staining in tumor tissues but not in non neoplasic mucosa.CONCLUSION: Experimental gastric tumors seem to produce more reactive oxygen species than non neoplasic gastric tissue. The reduction of oxidative stress and gastric tumor incidence in rats were induced by the intake of ascorbic acid. Therefore, it may have a role in the prevention of gastric carcinoma.

  15. Influence of Oxidation and Reduction Treatments on the Photorefractive Properties of Mg:In:Fe:LiNbO3 Crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of Mg:In:Fe:LiNbO3 crystals were grown by Czochralski technique; their absorption spectra and photo scattering resistance ability after oxidation or reduction treatment were measured by light spot distortion method, and their response time and exponential gain coefficient were tested by two-beam coupling experiment. Besides, the effective carrier concentration has been calculated. The results showed that the absorption edges of reduced and oxidized crystals are respectively shifted to violet and Einstein compared with those of the growth state crystal. From oxidation state to growth state to reduction state of the samples, the photo scattering resistance ability and response time decrease while the exponential gain coefficient and concentration of effective carriers increase. The reduction treatment was necessary for the Mg:In:Fe:LiNbO3 crystals to enhance their photorefractive properties.

  16. System and method for selective catalytic reduction of nitrogen oxides in combustion exhaust gases

    Science.gov (United States)

    Sobolevskiy, Anatoly; Rossin, Joseph A

    2014-04-08

    A multi-stage selective catalytic reduction (SCR) unit (32) provides efficient reduction of NOx and other pollutants from about 50-550.degree. C. in a power plant (19). Hydrogen (24) and ammonia (29) are variably supplied to the SCR unit depending on temperature. An upstream portion (34) of the SCR unit catalyzes NOx+NH.sub.3 reactions above about 200.degree. C. A downstream portion (36) catalyzes NOx+H.sub.2 reactions below about 260.degree. C., and catalyzes oxidation of NH.sub.3, CO, and VOCs with oxygen in the exhaust above about 200.degree. C., efficiently removing NOx and other pollutants over a range of conditions with low slippage of NH.sub.3. An ammonia synthesis unit (28) may be connected to the SCR unit to provide NH.sub.3 as needed, avoiding transport and storage of ammonia or urea at the site. A carbonaceous gasification plant (18) on site may supply hydrogen and nitrogen to the ammonia synthesis unit, and hydrogen to the SCR unit.

  17. Reduction of graphene oxide/alginate composite hydrogels for enhanced adsorption of hydrophobic compounds.

    Science.gov (United States)

    Kim, Semin; Yoo, Youngjae; Kim, Hanbit; Lee, Eunju; Lee, Jae Young

    2015-10-01

    Carbon-based materials, consisting of graphene oxide (GO) or reduced GO (rGO), possess unique abilities to interact with various molecules. In particular, rGO materials hold great promise for adsorption and delivery applications of hydrophobic molecules. However, conventional production and/or usage of rGO in aqueous solution often causes severe aggregation due to its low water solubility and thus difficulties in handling and applications. In our study, to prevent the severe aggregation of GO during reduction and to achieve a high adsorption capacity with hydrophobic compounds, GO/alginate composite hydrogels were first prepared and then reduced in an aqueous ascorbic acid solution at 37 °C. Adsorption studies with a model hydrophobic substance, rhodamine B, revealed that the reduced composite hydrogels are more highly absorbent than the unreduced hydrogels. In addition, the adsorption properties of the composite hydrogels, which are consequences of hydrophobic and ionic interactions, could be modulated by controlling the degree of reduction for the adsorption of different molecules. The composite hydrogels embedding rGO can be very useful in applications related to drug delivery, waste treatment, and biosensing.

  18. Enhanced oxygen reduction activity on surface-decorated perovskite thin films for solid oxide fuel cells

    KAUST Repository

    Mutoro, Eva

    2011-01-01

    Surface-decoration of perovskites can strongly affect the oxygen reduction activity, and therefore is a new and promising approach to improve SOFC cathode materials. In this study, we demonstrate that a small amount of secondary phase on a (001) La 0.8Sr 0.2CoO 3-δ (LSC) surface can either significantly activate or passivate the electrode. LSC (001) microelectrodes prepared by pulsed laser deposition on a (001)-oriented yttria-stabilized zirconia (YSZ) substrate were decorated with La-, Co-, and Sr-(hydr)oxides/carbonates. "Sr"-decoration with nanoparticle coverage in the range from 50% to 80% of the LSC surface enhanced the surface exchange coefficient, k q, by an order of magnitude while "La"- decoration and "Co"-decoration led to no change and reduction in k q, respectively. Although the physical origin for the enhancement is not fully understood, results from atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy suggest that the observed k q enhancement for "Sr"-decorated surfaces can be attributed largely to catalytically active interface regions between surface Sr-enriched particles and the LSC surface. © 2011 The Royal Society of Chemistry.

  19. Production of metallic nanopowders (Mg, Al by solar carbothermal reduction of their oxides at low pressure

    Directory of Open Access Journals (Sweden)

    J. Puig

    2016-06-01

    Full Text Available The carbothermal reduction of MgO and Al2O3 in argon flow at low pressure allows to lower the onset temperature of metal vapor formation. Thermodynamic calculations indicate that metal formation begins at 1400 and 1700 K for a primary vacuum (1000 Pa, respectively, for Mg and Al. In the experimental section, concentrated solar energy was used for the process heating in order to favor energy savings. The products of the reaction between MgO or Al2O3 and 2 varieties of carbon (graphite, carbon black in flowing argon atmosphere at a total pressure of around 1000 to 1600 Pa were studied using X-ray diffraction, and microstructure observations revealed the formation of metallic nanopowders with some by-products. Metallic conversions close to 45 wt% and 52 wt%, respectively, for Mg and Al, were obtained. The low conversion yield of the carbothermal reduction of MgO can be attributed to a backward reaction reforming MgO powder and to a sintering process between oxide particles at high temperature. Aluminum production challenge is to avoid formation of undesired by-products: Al2O, Al4C3 and Al-oxycarbides. Advantages and weaknesses of the used process are described and some improvements are proposed to increase metallic yields.

  20. Reduction of Fe(III) oxides by phylogenetically and physiologically diverse thermophilic methanogens.

    Science.gov (United States)

    Yamada, Chihaya; Kato, Souichiro; Kimura, Satoshi; Ishii, Masaharu; Igarashi, Yasuo

    2014-09-01

    Three thermophilic methanogens (Methanothermobacter thermautotrophicus, Methanosaeta thermophila, and Methanosarcina thermophila) were investigated for their ability to reduce poorly crystalline Fe(III) oxides (ferrihydrite) and the inhibitory effects of ferrihydrite on their methanogenesis. This study demonstrated that Fe(II) generation from ferrihydrite occurs in the cultures of the three thermophilic methanogens only when H2 was supplied as the source of reducing equivalents, even in the cultures of Mst. thermophila that do not grow on and produce CH4 from H2/CO2. While supplementation of ferrihydrite resulted in complete inhibition or suppression of methanogenesis by the thermophilic methanogens, ferrihydrite reduction by the methanogens at least partially alleviates the inhibitory effects. Microscopic and crystallographic analyses on the ferrihydrite-reducing Msr. thermophila cultures exhibited generation of magnetite on its cell surfaces through partial reduction of ferrihydrite. These findings suggest that at least certain thermophilic methanogens have the ability to extracellularly transfer electrons to insoluble Fe(III) compounds, affecting their methanogenic activities, which would in turn have significant impacts on materials and energy cycles in thermophilic anoxic environments. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  1. Reduction of graphene oxide/alginate composite hydrogels for enhanced adsorption of hydrophobic compounds

    Science.gov (United States)

    Kim, Semin; Yoo, Youngjae; Kim, Hanbit; Lee, Eunju; Lee, Jae Young

    2015-10-01

    Carbon-based materials, consisting of graphene oxide (GO) or reduced GO (rGO), possess unique abilities to interact with various molecules. In particular, rGO materials hold great promise for adsorption and delivery applications of hydrophobic molecules. However, conventional production and/or usage of rGO in aqueous solution often causes severe aggregation due to its low water solubility and thus difficulties in handling and applications. In our study, to prevent the severe aggregation of GO during reduction and to achieve a high adsorption capacity with hydrophobic compounds, GO/alginate composite hydrogels were first prepared and then reduced in an aqueous ascorbic acid solution at 37 °C. Adsorption studies with a model hydrophobic substance, rhodamine B, revealed that the reduced composite hydrogels are more highly absorbent than the unreduced hydrogels. In addition, the adsorption properties of the composite hydrogels, which are consequences of hydrophobic and ionic interactions, could be modulated by controlling the degree of reduction for the adsorption of different molecules. The composite hydrogels embedding rGO can be very useful in applications related to drug delivery, waste treatment, and biosensing.

  2. Carbon nanotubes loaded with vanadium oxide for reduction NO with NH3 at low temperature☆

    Institute of Scientific and Technical Information of China (English)

    Shuli Bai; Shengtao Jiang; Huanying Li; Yujiang Guan

    2015-01-01

    The catalytic activity of carbon nanotubes-supported vanadium oxide (V2O5/CNTs) catalysts in the selective catalytic reduction (SCR) of NO with NH3 at low temperatures (≤250 °C) was investigated. The effects of V2O5 loading, reaction temperature, and presence of SO2 on the SCR activity were evaluated. The results show that V2O5/CNTs catalysts exhibit high activity for NO reduction with NH3 at low-temperatures. The catalysts also show very high stability in the presence of SO2. More interestingly, their activities are significantly promoted in-stead of being poisoned by SO2. The promoting effect of SO2 is distinctly associated with V2O5 loading, particularly maximized at low V2O5 loading, which indicated the role of CNTs support in this effect. The promoting effect of SO2 at low temperatures suggests that V2O5/CNTs catalysts are promising catalytic materials for low-temperature SCR reactions.

  3. Spontaneous electrochemical treatment for sulfur recovery by a sulfide oxidation/vanadium(V) reduction galvanic cell.

    Science.gov (United States)

    Kijjanapanich, Pimluck; Kijjanapanich, Pairoje; Annachhatre, Ajit P; Esposito, Giovanni; Lens, Piet N L

    2015-02-01

    Sulfide is the product of the biological sulfate reduction process which gives toxicity and odor problems. Wastewaters or bioreactor effluents containing sulfide can cause severe environmental impacts. Electrochemical treatment can be an alternative approach for sulfide removal and sulfur recovery from such sulfide rich solutions. This study aims to develop a spontaneous electrochemical sulfide oxidation/vanadium(V) reduction cell with a graphite electrode system to recover sulfide as elemental sulfur. The effects of the internal and external resistance on the sulfide removal efficiency and electrical current produced were investigated at different pH. A high surface area of the graphite electrode is required in order to have as less internal resistance as possible. In this study, graphite powder was added (contact area >633 cm(2)) in order to reduce the internal resistance. A sulfide removal efficiency up to 91% and electrical charge of more than 400 C were achieved when using five graphite rods supplemented with graphite powder as the electrode at an external resistance of 30 Ω and a sulfide concentration of 250 mg L(-1). Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Reduction of nitric oxide emissions of stationary diesel engines with SCR and urea as reduction agents. Stickstoffoxidminderung bei stationaeren Dieselmotoren mittels SCR und Harnstoff als Reduktionsmittel

    Energy Technology Data Exchange (ETDEWEB)

    Koebel, M.; Elsener, M.; Eicher, H.P.

    1991-03-01

    Experiments were carried out to determine whether urea can replace ammonia in the selective catalytic reduction of nitric oxides. Pyrolysis experiments with aqueous urea solutions showed that it depended on the conditions of decomposition whether ammonia or urea was produced in changing quantities. Like pure ammonia the pyrolysis-gas mixture can be used in SCR catalytic converters with nitric oxides. Experiments with the exhaust gas of a diesel engine showed that the method also works in practice and is basically ready for application. Successfull application on a wider basis however can only start after overcoming the difficult technical problems of administering the reduction agent, process control, intermitting operation and service life of catalytic converter. (orig.).

  5. Direct methane solid oxide fuel cells based on catalytic partial oxidation enabling complete coking tolerance of Ni-based anodes

    Science.gov (United States)

    Lee, Daehee; Myung, Jaeha; Tan, Jeiwan; Hyun, Sang-Hoon; Irvine, John T. S.; Kim, Joosun; Moon, Jooho

    2017-03-01

    Solid oxide fuel cells (SOFCs) can oxidize diverse fuels by harnessing oxygen ions. Benefited by this feature, direct utilization of hydrocarbon fuels without external reformers allows for cost-effective realization of SOFC systems. Superior hydrocarbon reforming catalysts such as nickel are required for this application. However, carbon coking on nickel-based anodes and the low efficiency associated with hydrocarbon fueling relegate these systems to immature technologies. Herein, we present methane-fueled SOFCs operated under conditions of catalytic partial oxidation (CPOX). Utilizing CPOX eliminates carbon coking on Ni and facilitates the oxidation of methane. Ni-gadolinium-doped ceria (GDC) anode-based cells exhibit exceptional power densities of 1.35 W cm-2 at 650 °C and 0.74 W cm-2 at 550 °C, with stable operation over 500 h, while the similarly prepared Ni-yttria stabilized zirconia anode-based cells exhibit a power density of 0.27 W cm-2 at 650 °C, showing gradual degradation. Chemical analyses suggest that combining GDC with the Ni anode prevents the oxidation of Ni due to the oxygen exchange ability of GDC. In addition, CPOX operation allows the usage of stainless steel current collectors. Our results demonstrate that high-performance SOFCs utilizing methane CPOX can be realized without deterioration of Ni-based anodes using cost-effective current collectors.

  6. Sulfate reduction and methane oxidation in continental margin sediments influenced by irrigation (South-East Atlantic off Namibia)

    Science.gov (United States)

    Fossing, Henrik; Ferdelman, Timothy G.; Berg, Peter

    2000-03-01

    Sulfate reduction rates (SRR) and concentrations of SO 42-, H 2S, pyrite sulfur, total sulfur, CH 4, and organic carbon were measured with high depth resolution through the entire length of the SO 42--zone and well into the CH 4-zone at two continental slope stations in the eastern South Atlantic (Benguela upwelling area). The sediments were characterized by a high organic carbon content of approx. 7.5% at GeoB 3703 and 3.7% at GeoB 3714. At GeoB 3703 SO 42- concentrations decreased linearly with depth to about 40 μM at the sulfate-methane transition zone (SMT) at 3.5 m, while at GeoB 3714, SO 42- remained at sea water concentration in the top 2 m of the sediment and then decreased linearly to about 70 μM at the SMT at 6 m. Direct rate measurements of SRR ( 35SO 42-) showed that the highest SRR occurred within the surface 3-5 cm with peak rates of up to 20 and 7 nmol SO 42- cm -3 day -1 at GeoB 3703 and GeoB 3714, respectively. SRR decreased quasi-exponentially with depth at GeoB 3703 and the cumulative SRR over the length of the SO 42- zone resulted in an areal SRR (SRR area) of 1114-3493 μmol m -2 day -1 (median value: 2221 μmol m -2 day -1) at GeoB 3703 with more than 80% of the total sulfate reduction proceeding in the top 30 cm sediment. At GeoB 3714 SRR exhibited more scatter with a cumulative SRR area of 398-1983 μmol m -2 day -1 (median value: 1251 μmol m -2 day -1) and with >60% of the total sulfate reduction occurring below a depth of 30 cm due partially to a deeply buried zone of sulfate reduction located between 3 and 5 m depths. SRR peaks were also observed in SMT of both cores, ostensibly associated with methane oxidation, but with rates about 10 times lower than at the surface. Modeled SRR balanced both methane oxidation rates and measured SRR within the SMT, but severely underestimated by up to 89% the total SRR area that were obtained from direct measurements. Modeled and measured SRR were reconciled by including solute transport by

  7. Direct Observation of an Oxepin from a Bacterial Cytochrome P450-Catalyzed Oxidation.

    Science.gov (United States)

    Stok, Jeanette E; Chow, Sharon; Krenske, Elizabeth H; Farfan Soto, Clementina; Matyas, Csongor; Poirier, Raymond A; Williams, Craig M; De Voss, James J

    2016-03-18

    The cytochromes P450 are hemoproteins that catalyze a range of oxidative C-H functionalization reactions, including aliphatic and aromatic hydroxylation. These transformations are important in a range of biological contexts, including biosynthesis and xenobiotic biodegradation. Much work has been carried out on the mechanism of aliphatic hydroxylation, implicating hydrogen atom abstraction, but aromatic hydroxylation is postulated to proceed differently. One mechanism invokes as the key intermediate an arene oxide (and/or its oxepin tautomer). Conclusive isolation of this intermediate has remained elusive and, currently, direct formation of phenols from a Meisenheimer intermediate is believed to be favored. We report here the identification of a P450 [P450cam (CYP101A1) and P450cin (CYP176A1)]-generated arene oxide as a product of in vitro oxidation of tert-butylbenzene. Computations (CBS-QB3) predict that the arene oxide and oxepin have similar stabilities to other arene oxides/oxepins implicated (but not detected) in P450-mediated transformations, suggesting that arene oxides can be unstable terminal products of P450-catalyzed aromatic oxidation that can explain the origin of some observed metabolites.

  8. Nitrogen oxides from waste incineration: control by selective non-catalytic reduction.

    Science.gov (United States)

    Zandaryaa, S; Gavasci, R; Lombardi, F; Fiore, A

    2001-01-01

    An experimental study of the selective non-catalytic reduction (SNCR) process was carried out to determine the efficiency of NOx removal and NH3 mass balance, the NOx reducing reagent used. Experimental tests were conducted on a full-scale SNCR system installed in a hospital waste incineration plant. Anhydrous NH3 was injected at the boiler entrance for NOx removal. Ammonia was analyzed after each flue-gas treatment unit in order to establish its mass balance and NH3 slip in the stack gas was monitored as well. The effective fraction of NH3 for the thermal NOx reduction was calculated from measured values of injected and residual NH3. Results show that a NOx reduction efficiency in the range of 46.7-76.7% is possible at a NH3/NO molar ratio of 0.9-1.5. The fraction of NH3 used in NOx removal was found to decrease with rising NH3/NO molar ratio. The NH3 slip in the stack gas was very low, below permitted limits, even at the higher NH3 dosages used. No direct correlation was found between the NH3/NO molar ratio and the NH3 slip in the stack gas since the major part of the residual NH3 was converted into ammonium salts in the dry scrubbing reactor and subsequently collected in the fabric filter. Moreover, another fraction of NH3 was dissolved in the scrubbing liquor.

  9. Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.

    Science.gov (United States)

    Toh, Rou Jun; Sofer, Zdeněk; Pumera, Martin

    2015-11-16

    Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Direct Measurement of Light Speed Reduction in a Rubidium Vapour Medium Coherently Prepared by Electromagnetically Induced Transparency

    Institute of Scientific and Technical Information of China (English)

    涂鲜花; 王谨; 江开军; 何明; 李可; 仲嘉琪; 詹明生

    2003-01-01

    We have experimentally observed the reduction of light speed in a rubidium vapour medium coherently prepared by electromagnetically induced transparency.The light speed reduction was deduced by directly measuring the time delay of a probe light when it passed through the medium.The time delay varies with the intensity of the coupling laser,and the typical time delay we recorded was 1.8 μs,corresponding to a light speed of 56000m/s.

  11. Effect of reduction method on the performance of Pd catalysts supported on activated carbon for the selective oxidation of glucose

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The effect of the reduction method on the catalytic properties of palladium catalysts supported on activated carbon for the oxidation of D-glucose was examined.The reduction methods investigated include argon glow discharge plasma reduction at room temperature,reduction by flowing hydrogen at elevated temperature,and reduction by formaldehyde at room temperature.The plasma-reduced catalyst shows the smallest metal particles with a narrow size distribution that leads to a much higher activity.The catalyst characteristics show that the plasma reduction increases the amount of oxygen-containing functional groups,which significantly enhances the hydrophilic property of the activated carbon and improves the dispersion of the metal.

  12. Nitrate reduction, nitrous oxide formation, and anaerobic ammonia oxidation to nitrite in the gut of soil-feeding termites (Cubitermes and Ophiotermes spp.)

    KAUST Repository

    Ngugi, David

    2011-11-28

    Soil-feeding termites play important roles in the dynamics of carbon and nitrogen in tropical soils. Through the mineralization of nitrogenous humus components, their intestinal tracts accumulate enormous amounts of ammonia, and nitrate and nitrite concentrations are several orders of magnitude above those in the ingested soil. Here, we studied the metabolism of nitrate in the different gut compartments of two Cubitermes and one Ophiotermes species using 15N isotope tracer analysis. Living termites emitted N 2 at rates ranging from 3.8 to 6.8nmolh -1 (g fresh wt.) -1. However, in homogenates of individual gut sections, denitrification was restricted to the posterior hindgut, whereas nitrate ammonification occurred in all gut compartments and was the prevailing process in the anterior gut. Potential rates of nitrate ammonification for the entire intestinal tract were tenfold higher than those of denitrification, implying that ammonification is the major sink for ingested nitrate in the intestinal tract of soil-feeding termites. Because nitrate is efficiently reduced already in the anterior gut, reductive processes in the posterior gut compartments must be fuelled by an endogenous source of oxidized nitrogen species. Quite unexpectedly, we observed an anaerobic oxidation of 15N-labelled ammonia to nitrite, especially in the P4 section, which is presumably driven by ferric iron; nitrification and anammox activities were not detected. Two of the termite species also emitted substantial amounts of N 2O, ranging from 0.4 to 3.9nmolh -1 (g fresh wt.) -1, providing direct evidence that soil-feeding termites are a hitherto unrecognized source of this greenhouse gas in tropical soils. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  13. Biological Oxidation of Fe(II) in Reduced Nontronite Coupled with Nitrate Reduction by Pseudogulbenkiania sp. Strain 2002

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Linduo; Dong, Hailiang; Kukkadapu, Ravi K.; Agrawal, A.; Liu, Deng; Zhang, Jing; Edelmann, Richard E.

    2013-10-15

    Nitrate contamination in soils, sediments, and water bodies is a significant issue. Although much is known about nitrate degradation in these environments, especially via microbial pathways, a complete understanding of all degradation processes, especially in clay mineral-rich soils, is still lacking. The objective of this study was to study the potential of removing nitrate contaminant using structural Fe(II) in clay mineral nontronite. Specifically, the coupled processes of microbial oxidation of Fe(II) in microbially reduced nontronite (NAu-2) and nitrate reduction by Pseudogulbenkiania species strain 2002 was investigated. Bio-oxidation experiments were conducted in bicarbonate-buffered medium under both growth and nongrowth conditions. The extents of Fe(II) oxidation and nitrate reduction were measured by wet chemical methods. X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and 57Fe-Mössbauer spectroscopy were used to observe mineralogical changes associated with Fe(III) reduction and Fe(II) oxidation in nontronite. The bio-oxidation extent under growth and nongrowth conditions reached 93% and 57%, respectively. Over the same time period, nitrate was completely reduced under both conditions to nitrogen gas (N2), via an intermediate product nitrite. Magnetite was a mineral product of nitrate-dependent Fe(II) oxidation, as evidenced by XRD data and TEM diffraction patterns. The results of this study highlight the importance of iron-bearing clay minerals in the global nitrogen cycle with potential applications in nitrate removal in soils.

  14. Direct electrochemical production of Ti-10W alloys from mixed oxide preform precursors

    Energy Technology Data Exchange (ETDEWEB)

    Dring, K. [Imperial College London, Department of Materials, London SW7 2AZ (United Kingdom)]. E-mail: kevin.dring@imperial.ac.uk; Bhagat, R. [Imperial College London, Department of Materials, London SW7 2AZ (United Kingdom); Jackson, M. [Imperial College London, Department of Materials, London SW7 2AZ (United Kingdom); Dashwood, R. [Imperial College London, Department of Materials, London SW7 2AZ (United Kingdom); Inman, D. [Imperial College London, Department of Materials, London SW7 2AZ (United Kingdom)

    2006-08-10

    Ti-W alloys were produced via electrochemical reduction of TiO{sub 2}-WO{sub 3} mixed oxide preforms in a pre-electrolysed, molten calcium chloride electrolyte at 1173 K. Electrolysis voltages of 1500-3200 mV were applied for times ranging from 6 to 24 h across a graphite anode and Grade 2 commercial purity (CP) titanium cathodic current collector, which supported the ceramic precursors. Low-oxygen, homogeneous material was subsequently water washed and characterized to determine the level of residual species remaining from the reduction process, such as Cl and Ca. The microstructure (porosity and microchemistry) of the reduced material and microstructural examination of the mixed oxide feedstock (particle morphology, size and chemistry) were characterized using a field emission gun scanning electron microscope (FEG-SEM) with backscattered electron imaging (BSE) and X-ray energy dispersive spectrometry (X-EDS)

  15. Carbothermic reduction of electric arc furnace dust and calcination of waelz oxide by semi-pilot scale rotary furnace

    OpenAIRE

    Morcali M.H.; Yucel O.; Aydin A.; Derin B.

    2012-01-01

    The paper gives a common outline about the known recycling techniques from electric arc furnace dusts and describes an investigation of a pyrometallurgical process for the recovery of zinc and iron from electric arc furnace dusts (EAFD). In the waelz process, the reduction of zinc and iron from the waste oxides using solid carbon (lignite coal) was studied. In the reduction experiments; temperature, time and charge type (powder and pellet) were investigated in detail. It was demonstrate...

  16. Manganese extraction from high-iron-content manganese oxide ores by selective reduction roasting-acid leaching process using black charcoal as reductant

    Institute of Scientific and Technical Information of China (English)

    张元波; 赵熠; 游志雄; 段道显; 李光辉; 姜涛

    2015-01-01

    Reduction roasting-acid leaching process was utilized to process high-iron-content manganese oxide ore using black charcoal as reductant. The results indicate that, compared with the traditional reductant of anthracite, higher manganese extraction efficiency is achieved at lower roasting temperature and shorter residence time. The effects of roasting parameters on the leaching efficiency of Mn and Fe were studied, and the optimal parameters are determined as follows: roasting temperature is 650 °C, residence time is 40 min, and black charcoal dosage is 10% (mass fraction). Under these conditions, the leaching efficiency of Mn reaches 82.37% while that of Fe is controlled below 7%. XRD results show that a majority of MnO2 and Fe2O3in the raw ore are reduced to MnO and Fe3O4, respectively.

  17. On the mechanism of the direct pathway for formic acid oxidation at a Pt(111) electrode.

    Science.gov (United States)

    Xu, Jie; Yuan, Daofu; Yang, Fan; Mei, Dong; Zhang, Zunbiao; Chen, Yan-Xia

    2013-03-28

    In order determine whether formate is a reaction intermediate of the direct pathway for formic acid oxidation at a Pt electrode, formic acid (HCOOH) oxidation at a Pt(111) electrode has been studied by normal and fast scan voltammetry in 0.1 M HClO4 solutions with different HCOOH concentrations. The relationship between the HCOOH oxidation current density (j(ox)) and formate coverage (θ(formate)) is quantitatively analyzed. The kinetic simulation reveals that the previously proposed formate pathway, with decomposition of the bridge-bonded formate (HCOO(B)) as a rate determining step (rds), cannot be the main pathway responsible for the majority of the current for HCOOH oxidation. Instead, a kinetic model based on a mechanism with formic acid adsorption [structure: see text], along with simultaneous C-H bond activation as the rds for the direct pathway, explains the measured data well. It was found for the relatively slow rate of formic acid oxidation, that adsorption-desorption of the formate is faster, which competes for the surface sites for formic acid oxidation.

  18. Preparation and Characterization of Reduced Graphene Oxide Sheets via Water-Based Exfoliation and Reduction Methods

    OpenAIRE

    2013-01-01

    This research studied the synthesis of graphene oxide and graphene via a low-cost manufacturing method. The process started with the chemical oxidation of commercial graphite powder into graphite oxide by modified Hummer’s method, followed by the exfoliation of graphite oxide in distilled water using the ultrasound frequency from a laboratory ultrasonic bath. Finally, the oxygen functional groups on exfoliated graphite oxide or graphene oxide were eliminated by stirring in hot distilled water...

  19. Noise Reduction of MEMS Gyroscope Based on Direct Modeling for an Angular Rate Signal

    Directory of Open Access Journals (Sweden)

    Liang Xue

    2015-02-01

    Full Text Available In this paper, a novel approach for processing the outputs signal of the microelectromechanical systems (MEMS gyroscopes was presented to reduce the bias drift and noise. The principle for the noise reduction was presented, and an optimal Kalman filter (KF was designed by a steady-state filter gain obtained from the analysis of KF observability. In particular, the true angular rate signal was directly modeled to obtain an optimal estimate and make a self-compensation for the gyroscope without needing other sensor’s information, whether in static or dynamic condition. A linear fit equation that describes the relationship between the KF bandwidth and modeling parameter of true angular rate was derived from the analysis of KF frequency response. The test results indicated that the MEMS gyroscope having an ARW noise of 4.87°/h0.5 and a bias instability of 44.41°/h were reduced to 0.4°/h0.5 and 4.13°/h by the KF under a given bandwidth (10 Hz, respectively. The 1σ estimated error was reduced from 1.9°/s to 0.14°/s and 1.7°/s to 0.5°/s in the constant rate test and swing rate test, respectively. It also showed that the filtered angular rate signal could well reflect the dynamic characteristic of the input rate signal in dynamic conditions. The presented algorithm is proved to be effective at improving the measurement precision of the MEMS gyroscope.

  20. Reduction of nitric oxide and DNA/RNA oxidation products are associated with active disease in systemic lupus erythematosus patients.

    Science.gov (United States)

    Iriyoda, T M V; Stadtlober, N; Lozovoy, M A B; Delongui, F; Costa, N T; Reiche, E M V; Dichi, I; Simão, A N C

    2017-09-01

    The aims of the present study were to evaluate biomarkers of oxidative and nitrosative stress in systemic lupus erythematosus (SLE) patients, in particular products of DNA/RNA oxidative damage and their correlation with disease activity. This study included 188 controls and 203 patients; 153 with inactive SLE (SLEDAI Oxidative stress was assessed by tert-butyl hydroperoxide-initiated by chemiluminescence, advanced oxidation protein products (AOPP), total radical-trapping antioxidant parameter (TRAP), nitric oxide metabolites (NOx), and DNA/RNA oxidation products. Patients with SLE showed increased oxidative stress, as demonstrated by the augmentation of lipid hydroperoxides ( p oxidation products were inversely and independently associated with disease activity ( p oxidation products ( r(2):0.051; p = 0.002) and about 9% of this score by the levels of NOx ( r(2):0.091; p oxidation products and SLE disease activity, suggesting that oxidative/nitrosative stress markers may be useful in evaluating SLE disease activity and progression of the disease.

  1. Sensitivity of Chinese Industrial Wastewater Discharge Reduction to Direct Input Coefficients in an Input-output Context

    Institute of Scientific and Technical Information of China (English)

    TANG Zhipeng; GONG Peiping; LIU Weidong; LI Jiangsu

    2015-01-01

    Industrial wastewater discharge in China is increasing with the country's economic development and it is worthy of concern.The discharge is primarily relevant to the direct discharge coefficient of each sector of the economy,its direct input coefficient and the final demand in input-output models.In this study,we calculated the sensitivity of the reduction in the Chinese industrial wastewater discharge using the direct input coefficients based on the theory of error-transmission in an input-outpnt framework.Using input-output models,we calculated the direct and total industrial wastewater discharge coefficients.Analysis of 2007 input-output data of 30 sectors of the Chinese economy and of 30 provincial regions of China indicates that by lowering their direct input coefficients,the manufacturers of textiles,paper and paper products,chemical products,smelting and metal pressing,telecommunication equipment,computers and other electronic equipment will significantly reduce their amounts of industrial wastewater discharge.By lowering intra-provincial direct input coefficients to industrial sectors themselves of Jiangsu,Shandong and Zhejiang,there will be a significant reduction in industrial wastewater discharge for the country as a whole.Investment in production technology and improvement in organizational efficiency in these sectors and in these provinces can help lessen the direct input coefficients,thereby effectively achieving a reduction in industrial wastewater discharge in China via industrial restructuring.

  2. Thermodynamic analysis of Direct Urea Solid Oxide Fuel Cell in combined heat and power applications

    Science.gov (United States)

    Abraham, F.; Dincer, I.

    2015-12-01

    This paper presents a comprehensive steady state modelling and thermodynamic analysis of Direct Urea Solid Oxide Fuel Cell integrated with Gas Turbine power cycle (DU-SOFC/GT). The use of urea as direct fuel mitigates public health and safety risks associated with the use of hydrogen and ammonia. The integration scheme in this study covers both oxygen ion-conducting solid oxide fuel cells (SOFC-O) and hydrogen proton-conducting solid oxide fuel cells (SOFC-H). Parametric case studies are carried out to investigate the effects of design and operating parameters on the overall performance of the system. The results reveal that the fuel cell exhibited the highest level of exergy destruction among other system components. Furthermore, the SOFC-O based system offers better overall performance than that with the SOFC-H option mainly due to the detrimental reverse water-gas shift reaction at the SOFC anode as well as the unique configuration of the system.

  3. Direct partial oxidation of methane to methanol: Reaction zones and role of catalyst location

    Institute of Scientific and Technical Information of China (English)

    Qijian Zhang; Dehua He; Qiming Zhu

    2008-01-01

    Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be divided into three reaction zones, namely pre-reaction zone, fierce reaction zone, and post-reaction zone, when the temperature was high enough to initiate a reaction. The oxidation of methane proceeded and was completed mostly in the fierce reaction zone. When the reactant mixture entered the post-reaction zone, only a small amount of produced methanol would bring about secondary reactions, because molecular oxygen had been exhausted in the fierce reaction zone. A catalyst, if necessary, should be placed either in the pre-reaction zone, to initiate a partial oxidation reaction at a lower temperature, or in the fierce reaction zone to control the homogeneous free radical reaction.

  4. Direct Irradiaton of Aryl Sulfides: Homolytic Fragmentation and Sensitized S-Oxidation.

    Science.gov (United States)

    Bonesi, Sergio M; Crespi, Stefano; Merli, Daniele; Manet, Ilse; Albini, Angelo

    2017-09-01

    The direct irradiation of diphenyl sulfide and p-substituted thioanisoles in the presence of oxygen was investigated by means of both steady state and laser flash photolysis experiments. Two competitive pathways took place from the triplet excited state of thioanisoles, C-S bond cleavage, finally leading to aryl sulfinic acid and sensitized oxidation leading to S-oxidation. Co-oxidation of dodecyl methyl sulfide occurred efficiently implying that an S-persulfoxide intermediate is involved during the sensitized oxidation. On the other hand, triplet state of diphenyl sulfide also showed competitive C-S bond cleavage giving phenyl sulfinic acid and ionization to diphenyl sulfide radical cation that in turn led to diphenyl sulfoxide. The rate constants of the above reactions were determined by time-resolved experiments.

  5. Monolayer-directed Assembly and Magnetic Properties of FePt Nanoparticles on Patterned Aluminum Oxide

    NARCIS (Netherlands)

    Yildirim, Oktay; Gang, Tian; Kinge, Sachin; Reinhoudt, David N.; Blank, Dave H.; Wiel, van der Wilfred G.; Rijnders, Guus; Huskens, Jurriaan

    2010-01-01

    FePt nanoparticles (NPs) were assembled on aluminum oxide substrates, and their ferromagnetic properties were studied before and after thermal annealing. For the first time, phosph(on)ates were used as an adsorbate to form self-assembled monolayers (SAMs) on alumina to direct the assembly of NPs ont

  6. Direct observation of surface reconstruction and termination on a complex metal oxide catalyst by electron microscopy

    KAUST Repository

    Zhu, Yihan

    2012-03-19

    On the surface: The surface reconstruction of an MoVTeO complex metal oxide catalyst was observed directly by various electron microscopic techniques and the results explain the puzzling catalytic behavior. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Controlling the Formation of Nanocavities in Kirkendall Nanoobjects through Sequential Thermal Ex Situ Oxidation and In Situ Reduction Reactions.

    Science.gov (United States)

    Mel, Abdel-Aziz El; Tessier, Pierre-Yves; Buffiere, Marie; Gautron, Eric; Ding, JunJun; Du, Ke; Choi, Chang-Hwan; Konstantinidis, Stephanos; Snyders, Rony; Bittencourt, Carla; Molina-Luna, Leopoldo

    2016-06-01

    Controlling the porosity, the shape, and the morphology of Kirkendall hollow nanostructures is the key factor to tune the properties of these tailor-made nanomaterials which allow in turn broadening their applications. It is shown that by applying a continuous oxidation to copper nanowires following a temperature ramp protocol, one can synthesize cuprous oxide nanotubes containing periodic copper nanoparticles. A further oxidation of such nanoobjects allows obtaining cupric oxide nanotubes with a bamboo-like structure. On the other hand, by applying a sequential oxidation and reduction reactions to copper nanowires, one can synthesize hollow nanoobjects with complex shapes and morphologies that cannot be obtained using the Kirkendall effect alone, such as necklace-like cuprous oxide nanotubes, periodic solid copper nanoparticles or hollow cuprous oxide nanospheres interconnected with single crystal cuprous oxide nanorods, and aligned and periodic hollow nanospheres embedded in a cuprous oxide nanotube. The strategy demonstrated in this study opens new avenues for the engineering of hollow nanostructures with potential applications in gas sensing, catalysis, and energy storage.

  8. Effect of exhaust gas recirculation on diesel engine nitrogen oxide reduction operating with jojoba methyl ester

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, H.E. [Mechanical Power Department, Faculty of Engineering, Mattaria, Helwan University, 9 k Eltaaweniat, Nasr Road, P.O. Box 11718, Cairo (Egypt)

    2009-10-15

    Jojoba methyl ester (JME) has been used as a renewable fuel in numerous studies evaluating its potential use in diesel engines. These studies showed that this fuel is good gas oil substitute but an increase in the nitrogenous oxides emissions was observed at all operating conditions. The aim of this study mainly was to quantify the efficiency of exhaust gas recirculation (EGR) when using JME fuel in a fully instrumented, two-cylinder, naturally aspirated, four-stroke direct injection diesel engine. The tests were carried out in three sections. Firstly, the measured performance and exhaust emissions of the diesel engine operating with diesel fuel and JME at various speeds under full load are determined and compared. Secondly, tests were performed at constant speed with two loads to investigate the EGR effect on engine performance and exhaust emissions including nitrogenous oxides (NO{sub x}), carbon monoxide (CO), unburned hydrocarbons (HC) and exhaust gas temperatures. Thirdly, the effect of cooled EGR with high ratio at full load on engine performance and emissions was examined. The results showed that EGR is an effective technique for reducing NO{sub x} emissions with JME fuel especially in light-duty diesel engines. With the application of the EGR method, the CO and HC concentration in the engine-out emissions increased. For all operating conditions, a better trade-off between HC, CO and NO{sub x} emissions can be attained within a limited EGR rate of 5-15% with very little economy penalty. (author)

  9. (Fundamental studies in oxidation-reduction in relation to water photolysis)

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, J.K.

    1991-01-01

    Our research has been directed at understanding three elementary processes that are central to developing membrane-based integrated chemical systems for water photolysis. These are: (1) the role of interfaces in charge separation/recombination reactions, (2) pathways for transmembrane charge separation, and (3) mechanisms of water oxidation catalyzed by transition metal coordination complexes. Historically, the chemical dynamics of each of these processes has been poorly understood, with numerous unresolved issues and conflicting viewpoints appearing in the literature. Our experimental systems comprise primarily unilamellar vesicles that have been doped with amphiphilic viologens which function as transmembrane charge relays. These systems are experimentally highly tractable and versatile, are conceptually simple, and have been widely used in a variety of organized microphase media and prototypic devices. As such, they are ideal for identifying basic principles governing reactivity.

  10. Electrochemical preparation of few layer-graphene nanosheets via reduction of oriented exfoliated graphene oxide thin films in acetamide-urea-ammonium nitrate melt under ambient conditions

    Energy Technology Data Exchange (ETDEWEB)

    Dilimon, V.S.; Sampath, S., E-mail: sampath2562@gmail.co

    2011-01-31

    Electrochemical reduction of exfoliated graphene oxide, prepared from pre-exfoliated graphite, in acetamide-urea-ammonium nitrate ternary eutectic melt results in few layer-graphene thin films. Negatively charged exfoliated graphene oxide is attached to positively charged cystamine monolyer self-assembled on a gold surface. Electrochemical reduction of the oriented graphene oxide film is carried out in a room temperature, ternary molten electrolyte. The reduced film is characterized by atomic force microscopy (AFM), conductive AFM, Fourier-transform infrared spectroscopy and Raman spectroscopy. Ternary eutectic melt is found to be a suitable medium for the regulated reduction of graphene oxide to reduced graphene oxide-based sheets on conducting surfaces.

  11. Protection against osteoporosis by statins is linked to a reduction of oxidative stress and restoration of nitric oxide formation in aged and ovariectomized rats.

    Science.gov (United States)

    Yin, Hong; Shi, Zhen-Guo; Yu, Yong-Sheng; Hu, Jing; Wang, Ru; Luan, Zhi-Peng; Guo, Dai-Hong

    2012-01-15

    Statins, 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, have been used as a cholesterol-lowering drug to treat hyperlipidemia clinically. In recent years, accumulating evidence indicates the possible beneficial effect of statins on osteoporosis. The aim of present study was to investigate whether protection against osteoporosis by statins is linked to a reduction of oxidative stress and restoration of nitric oxide (NO) formation in aged and ovariectomized rats. The aged and ovariectomized rats were used as two models of osteoporosis for evaluation of the effect of simvastatin. It was found that simvastatin abated oxidative stress, increased NO production, subsequently attenuating osteoporosis in two models. In the in vitro studies, the protective effects against H(2)O(2)-induced cell injury were examined in the MG-63 human osteoblastic cells. It was found that simvastatin ameliorated H(2)O(2)-induced cell loss and cell apoptosis and increased alkaline phosphatase (ALP) activity in osteoblastic cells. Simvastatin abated oxidative stress through enhancing catalase, heme oxygenase 1 (HO-1), and superoxide dismutase (SOD) activity and suppressing NADPH oxidase activity. In addition, simvastatin raised nitric oxide synthase (NOS) activity and eNOS expression at basal condition; inhibited NOS activity and iNOS expression when treated with H(2)O(2). In conclusion, protection against osteoporosis by statins is linked to a reduction of oxidative stress and restoration of NO formation in aged and ovariectomized rats.

  12. Electrochemical Reduction of Carbon Dioxide to Methanol by Direct Injection of Electrons into Immobilized Enzymes on a Modified Electrode.

    Science.gov (United States)

    Schlager, Stefanie; Dumitru, Liviu Mihai; Haberbauer, Marianne; Fuchsbauer, Anita; Neugebauer, Helmut; Hiemetsberger, Daniela; Wagner, Annika; Portenkirchner, Engelbert; Sariciftci, Niyazi Serdar

    2016-03-21

    We present results for direct bio-electrocatalytic reduction of CO2 to C1 products using electrodes with immobilized enzymes. Enzymatic reduction reactions are well known from biological systems where CO2 is selectively reduced to formate, formaldehyde, or methanol at room temperature and ambient pressure. In the past, the use of such enzymatic reductions for CO2 was limited due to the necessity of a sacrificial co-enzyme, such as nicotinamide adenine dinucleotide (NADH), to supply electrons and the hydrogen equivalent. The method reported here in this paper operates without the co-enzyme NADH by directly injecting electrons from electrodes into immobilized enzymes. We demonstrate the immobilization of formate, formaldehyde, and alcohol dehydrogenases on one-and-the-same electrode for direct CO2 reduction. Carbon felt is used as working electrode material. An alginate-silicate hybrid gel matrix is used for the immobilization of the enzymes on the electrode. Generation of methanol is observed for the six-electron reduction with Faradaic efficiencies of around 10%. This method of immobilization of enzymes on electrodes offers the opportunity for electrochemical application of enzymatic electrodes to many reactions in which a substitution of the expensive sacrificial co-enzyme NADH is desired.

  13. Weight reduction and the impaired plasma-derived free fatty acid oxidation in type 2 diabetic subjects

    NARCIS (Netherlands)

    Blaak, EE; Wolffenbuttel, BHR; Saris, WHM; Pelsers, MMAL; Wagenmakers, AJM

    2001-01-01

    In a previous study the oxidation of plasma free fatty acids (FFA) under baseline conditions and during exercise was lower in type 2 diabetic subjects compared with weight-matched controls. The present study intended to investigate the effect of weight reduction (very low calorie diet) on plasma FFA

  14. MERCURY OXIDATION PROMOTED BY A SELECTIVE CATALYTIC REDUCTION CATALYST UNDER SIMULATED POWDER RIVER BASIN COAL COMBUSTION CONDITIONS

    Science.gov (United States)

    A bench-scale reactor consisting of a natural gas burner and an electrically heated reactor housing a selective catalytic reduction (SCR) catalyst was constructed for studying elemental mercury oxidation under SCR conditions. A low sulfur Power River Basin (PRB) coal combustion ...

  15. Chemically enhanced biological NOx removal from flue gases : nitric oxide and ferric EDTA reduction in BioDeNox reactors

    NARCIS (Netherlands)

    Maas, van der P.M.F.

    2005-01-01

    The emission of nitrogen oxides (NOx) to the atmosphere is a major environmental problem. To abate NOx emissions from industrial flue gases, to date, mainly chemical processes like selective catalytic reduction (SCR) are applied. All these processes require high temperatures (>300 °C) and expensi

  16. Isothermal Reduction of Oxide Scale on Hot-Rolled, Low-Carbon Steel in 10 pct H2-Ar

    Science.gov (United States)

    He, Yongquan; Jia, Tao; Li, Zhifeng; Cao, Guangming; Liu, Zhenyu; Li, Jun

    2016-10-01

    The isothermal reduction of oxide scale on hot-rolled, low-carbon steel strip in 10 pct H2-Ar mixtures in the temperature range of 673 K to 1073 K (400 °C to 800 °C) was investigated by using a thermo-gravimetric analyzer (TGA). During heating under an argon atmosphere, magnetite/iron eutectoid and proeutectoid magnetite in the oxide scale successively transformed into wüstite at a temperature above 843 K (570 °C). The kinetic plot of the isothermal reduction assumes a sigmoid shape, including induction, acceleration, and finally the decaying stage. Fitting the kinetic curve to mathematical models, the reaction at 1073 K (800 °C) and 773 K (500 °C) were determined to be controlled by phase-boundary-controlled reaction and three-dimensional growth of nuclei, respectively. The reduction product varies with temperature and itself affects the kinetics. Porous and dense iron were, respectively, obtained below and above 873 K (600 °C). A "rate-minimum" was observed at 973 K (700 °C) due to the formation of dense iron that blocks the gas diffusion. Due to the structural transformation of oxide scale during heating, the reactant depends on the heating process. However, compared with the oxide scale structure, the temperature is more important in determining the reduction kinetics at temperatures above 973 K (700 °C).

  17. Weight reduction and the impaired plasma-derived free fatty acid oxidation in type 2 diabetic subjects

    NARCIS (Netherlands)

    Blaak, EE; Wolffenbuttel, BHR; Saris, WHM; Pelsers, MMAL; Wagenmakers, AJM

    2001-01-01

    In a previous study the oxidation of plasma free fatty acids (FFA) under baseline conditions and during exercise was lower in type 2 diabetic subjects compared with weight-matched controls. The present study intended to investigate the effect of weight reduction (very low calorie diet) on plasma FFA

  18. Assessing the influence of the carbon oxidation-reduction state on organic pollutant biodegradation in algal-bacterial photobioreactors

    NARCIS (Netherlands)

    Bahr, M.; Stams, A.J.M.; Rosa, de la F.; Garcia-Encina, P.; Munoz, R.

    2011-01-01

    The influence of the carbon oxidation-reduction state (CORS) of organic pollutants on their biodegradation in enclosed algal-bacterial photobioreactors was evaluated using a consortium of enriched wild-type methanotrophic bacteria and microalgae. Methane, methanol and glucose (with CORS -4, -2 and 0

  19. Preconditioning with Azadirachta indica ameliorates cardiorenal dysfunction through reduction in oxidative stress and extracellular signal regulated protein kinase signalling

    Directory of Open Access Journals (Sweden)

    Temidayo Olutayo Omóbòwálé

    2016-10-01

    Conclusions: Together, A. indica and vitamin C prevented IRI-induced cardiorenal dysfunction via reduction in oxidative stress, improvement in antioxidant defence system and increase in the ERK1/2 expressions. Therefore, A. indica can be a useful chemopreventive agent in the prevention and treatment of conditions associated with intestinal ischaemia-reperfusion injury.

  20. Ammonia Oxidation and Nitrite Reduction in the Verrucomicrobial Methanotroph Methylacidiphilum fumariolicum SolV

    Directory of Open Access Journals (Sweden)

    Sepehr S. Mohammadi

    2017-09-01

    Full Text Available The Solfatara volcano near Naples (Italy, the origin of the recently discovered verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV was shown to contain ammonium (NH4+ at concentrations ranging from 1 to 28 mM. Ammonia (NH3 can be converted to toxic hydroxylamine (NH2OH by the particulate methane monooxygenase (pMMO, the first enzyme of the methane (CH4 oxidation pathway. Methanotrophs rapidly detoxify the intermediate NH2OH. Here, we show that strain SolV performs ammonium oxidation to nitrite at a rate of 48.2 nmol NO2-.h−1.mg DW−1 under O2 limitation in a continuous culture grown on hydrogen (H2 as an electron donor. In addition, strain SolV carries out nitrite reduction at a rate of 74.4 nmol NO2-.h−1.mg DW−1 under anoxic condition at pH 5–6. This range of pH was selected to minimize the chemical conversion of nitrite (NO2- potentially occurring at more acidic pH values. Furthermore, at pH 6, we showed that the affinity constants (Ks of the cells for NH3 vary from 5 to 270 μM in the batch incubations with 0.5–8% (v/v CH4, respectively. Detailed kinetic analysis showed competitive substrate inhibition between CH4 and NH3. Using transcriptome analysis, we showed up-regulation of the gene encoding hydroxylamine dehydrogenase (haoA cells grown on H2/NH4+ compared to the cells grown on CH4/NO3- which do not have to cope with reactive N-compounds. The denitrifying genes nirk and norC showed high expression in H2/NH4+ and CH4/NO3- grown cells compared to cells growing at μmax (with no limitation while the norB gene showed downregulation in CH4/NO3- grown cells. These cells showed a strong upregulation of the genes in nitrate/nitrite assimilation. Our results demonstrate that strain SolV can perform ammonium oxidation producing nitrite. At high concentrations of ammonium this may results in toxic effects. However, at low oxygen concentrations strain SolV is able to reduce nitrite to N2O to cope with this toxicity.

  1. Electrolytic reduction of mixed (Fe, Ti) oxide using molten calcium chloride electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Panigrahi, Mrutyunjay, E-mail: mp@mail.tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-8577 (Japan); Iizuka, Atsushi; Shibata, Etsuro; Nakamura, Takashi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-8577 (Japan)

    2013-02-15

    electrochemically in a molten CaCl{sub 2} electrolyte at 950 Degree-Sign C. The metallic samples formed by electrolytic reduction of the mixed solid (Fe, Ti) oxide were analyzed using X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectroscopy, electron-probe microanalysis, X-ray fluorescence spectrometry, inductively coupled plasma atomic emission spectroscopy, ion chromatography, and oxygen and carbon analyzers. The oxide pellets were successfully reduced to a highly purified dense intermetallic solid of {beta}-Ti (FeTi{sub 4}) and FeTi containing low levels of impurities, for example, less than 0.01 mass% of carbon.

  2. Improved free energy profile for reduction of NO in cytochrome c dependent nitric oxide reductase (cNOR).

    Science.gov (United States)

    Blomberg, Margareta R A; Siegbahn, Per E M

    2016-07-15

    Quantum chemical calculations play an essential role in the elucidation of reaction mechanisms for redox-active metalloenzymes. For example, the cleavage and the formation of covalent bonds can usually not be described only on the basis of experimental information, but can be followed by the calculations. Conversely, there are properties, like reduction potentials, which cannot be accurately calculated. Therefore, computational and experimental data has to be carefully combined to obtain reliable descriptions of entire catalytic cycles involving electron and proton uptake from donors outside the enzyme. Such a procedure is illustrated here, for the reduction of nitric oxide (NO) to nitrous oxide and water in the membrane enzyme, cytochrome c dependent nitric oxide reductase (cNOR). A surprising experimental observation is that this reaction is nonelectrogenic, which means that no energy is conserved. On the basis of hybrid density functional calculations a free energy profile for the entire catalytic cycle is obtained, which agrees much better with experimental information on the active site reduction potentials than previous ones. Most importantly the energy profile shows that the reduction steps are endergonic and that the entire process is rate-limited by high proton uptake barriers during the reduction steps. This result implies that, if the reaction were electrogenic, it would become too slow when the gradient is present across the membrane. This explains why this enzyme does not conserve any of the free energy released. © 2016 Wiley Periodicals, Inc.

  3. Microsensor Measurements of Sulfate Reduction and Sulfide Oxidation in Compact Microbial Communities of Aerobic Biofilms Rid A-1977-2009

    DEFF Research Database (Denmark)

    KUHL, M.; JØRGENSEN, BB

    1992-01-01

    The microzonation of O2 respiration, H2S oxidation, and SO4(2-) reduction in aerobic trickling-filter biofilms was studied by measuring concentration profiles at high spatial resolution (25 to 100-mu-m) with microsensors for O2, S2-, and pH. Specific reaction rates were calculated from measured...... water. Turnover times of H2S and O2 in the reaction zone were only a few seconds owing to rapid bacterial H2S oxidation. Anaerobic H2S oxidation with NO3- could be induced by addition of nitrate to the medium. Total sulfate reduction rates increased when the availability of SO4(2-) or organic substrate...

  4. Nitric Oxide Production by the Human Intestinal Microbiota by Dissimilatory Nitrate Reduction to Ammonium

    Directory of Open Access Journals (Sweden)

    Joan Vermeiren

    2009-01-01

    Full Text Available The free radical nitric oxide (NO is an important signaling molecule in the gastrointestinal tract. Besides eukaryotic cells, gut microorganisms are also capable of producing NO. However, the exact mechanism of NO production by the gut microorganisms is unknown. Microbial NO production was examined under in vitro conditions simulating the gastrointestinal ecosystem using L-arginine or nitrate as substrates. L-arginine did not influence the microbial NO production. However, NO concentrations in the order of 90 ng NO-N per L feed medium were produced by the fecal microbiota from nitrate. N15 tracer experiments showed that nitrate was mainly reduced to ammonium by the dissimilatory nitrate reduction to ammonium (DNRA pathway. To our knowledge, this is the first study showing that gastrointestinal microbiota can generate substantial amounts of NO by DNRA and not by the generally accepted denitrification or L-arginine pathway. Further work is needed to elucidate the exact role between NO produced by the gastrointestinal microbiota and host cells.

  5. Simultaneous Reduction and Functionalization of Graphene Oxide by 4-Hydrazinobenzenesulfonic Acid for Polymer Nanocomposites

    Directory of Open Access Journals (Sweden)

    Song-Jie Qiao

    2016-02-01

    Full Text Available Graphene oxide (GO was functionalized and reduced simultaneously by a new reductant, 4-hydrazinobenzenesulfonic acid (HBS, with a one-step and environmentally friendly process. The hydrophilic sulfonic acid group in HBS was grafted onto the surface of GO through a covalent bond. The successful preparation of HBS reduced GO (HBS-rGO was testified by scanning electron microscope (SEM, X-ray diffraction (XRD, Raman spectroscopy, Fourier transform infrared spectra (FTIR, X-ray photoelectron spectroscopic (XPS and thermogravimetric analysis (TGA. The interlayer space of HBS-rGO was increased to 1.478 nm from 0.751 nm for GO, resulting in a subdued Van der Waals’ force between layers and less possibility to form aggregations. The aqueous dispersibility of graphene was improved to 13.49 mg/mL from 0.58 mg/mL after the functionalization. The viscosity of the epoxy resin based HBS-rGO composite could be regulated by an adjustment of the content of HBS-rGO. This study provides a new and applicable approach for the preparation of hydrophilic functionalized graphene, and makes it possible for the application of graphene in some functional polymer nanocomposites, such as specialty water-based coatings.

  6. Photo-induced reduction of graphene oxide coating on optical waveguide and consequent optical intermodulation.

    Science.gov (United States)

    Chong, W Y; Lim, W H; Yap, Y K; Lai, C K; De La Rue, R M; Ahmad, H

    2016-04-01

    Increased absorption of transverse-magnetic (TM)-polarised light by a graphene-oxide (GO) coated polymer waveguide has been observed in the presence of transverse-electric (TE)-polarised light. The GO-coated waveguide exhibits very strong photo-absorption of TE-polarised light--and acts as a TM-pass waveguide polariser. The absorbed TE-polarised light causes a significant temperature increase in the GO film and induces thermal reduction of the GO, resulting in an increase in optical-frequency conductivity and consequently increased optical propagation loss. This behaviour in a GO-coated waveguide gives the action of an inverted optical switch/modulator. By varying the incident TE-polarised light power, a maximum modulation efficiency of 72% was measured, with application of an incident optical power level of 57 mW. The GO-coated waveguide was able to respond clearly to modulated TE-polarised light with a pulse duration of as little as 100 μs. In addition, no wavelength dependence was observed in the response of either the modulation (TE-polarised light) or the signal (TM-polarised light).

  7. Synthesis of highly active and dual-functional electrocatalysts for methanol oxidation and oxygen reduction reactions

    Science.gov (United States)

    Zhao, Qi; Zhang, Geng; Xu, Guangran; Li, Yingjun; Liu, Baocang; Gong, Xia; Zheng, Dafang; Zhang, Jun; Wang, Qin

    2016-12-01

    The promising Pt-based ternary catalyst is crucial for polymer electrolyte membrane fuel cells (PEMFCs) due to improving catalytic activity and durability for both methanol oxidation reaction and oxygen reduction reaction. In this work, a facile strategy is used for the synthesis ternary RuMPt (M = Fe, Co, Ni, and Cu) nanodendrities catalysts. The ternary RuMPt alloys exhibit enhanced specific and mass activity, positive half-wave potential, and long-term stability, compared with binary Pt-based alloy and the commercial Pt/C catalyst, which is attributed to the high electron density and upshifting of the d-band center for Pt atoms, and synergistic catalytic effects among Pt, M, and Ru atoms by introducing a transition metal. Impressively, the ternary RuCoPt catalyst exhibits superior mass activity (801.59 mA mg-1) and positive half-wave potential (0.857 V vs. RHE) towards MOR and ORR, respectively. Thus, the RuMPt nanocomposite is a very promising material to be used as dual electrocatalyst in the application of PEMFCs.

  8. Conifer somatic embryogenesis: improvements by supplementation of medium with oxidation-reduction agents.

    Science.gov (United States)

    Pullman, Gerald S; Zeng, Xiaoyan; Copeland-Kamp, Brandi; Crockett, Jonathan; Lucrezi, Jacob; May, Sheldon W; Bucalo, Kylie

    2015-02-01

    A major barrier to the commercialization of somatic embryogenesis technology in loblolly pine (Pinus taeda L.) is recalcitrance of some high-value crosses to initiate embryogenic tissue (ET) and continue early-stage somatic embryo growth. Developing initiation and multiplication media that resemble the seed environment has been shown to decrease this recalcitrance. Glutathione (GSH), glutathione disulfide (GSSG), ascorbic acid and dehydroascorbate analyses were performed weekly throughout the sequence of seed development for female gametophyte and zygotic embryo tissues to determine physiological concentrations. Major differences in stage-specific oxidation-reduction (redox) agents were observed. A simple bioassay was used to evaluate potential growth-promotion of natural and inorganic redox agents added to early-stage somatic embryo growth medium. Compounds showing statistically significant increases in early-stage embryo growth were then tested for the ability to increase initiation of loblolly pine. Low-cost reducing agents sodium dithionite and sodium thiosulfate increased ET initiation for loblolly pine and Douglas fir (Mirb) Franco. Germination medium supplementation with GSSG increased somatic embryo germination. Early-stage somatic embryos grown on medium with or without sodium thiosulfate did not differ in GSH or GSSG content, suggesting that sodium thiosulfate-mediated growth stimulation does not involve GSH or GSSG. We have developed information demonstrating that alteration of the redox environment in vitro can improve ET initiation, early-stage embryo development and somatic embryo germination in loblolly pine.

  9. Estimation of the Postmortem Interval by Measuring Blood Oxidation-reduction Potential Values

    Directory of Open Access Journals (Sweden)

    Zhuqing Jiang

    2016-01-01

    Full Text Available Accurate estimation of the postmortem interval (PMI is an important task in forensic practice. In the last half-century, the use of postmortem biochemistry has become an important ancillary method in determining the time of death. The present study was carried out to determine the correlation between blood oxidation-reduction potential (ORP values and PMIs, and to develop a three-dimensional surface equation to estimate the PMI under various temperature conditions. A total of 48 rabbits were placed into six groups and sacrificed by air embolism. Blood was obtained from the right ventricle of each rabbit, and specimens were stored at 10°C, 15°C, 20°C, 25°C, 30°C, and 35°C. At different PMIs (once every 4 h, the blood ORP values were measured using a PB-21 electrochemical analyzer. Statistical analysis and curve fitting of the data yielded cubic polynomial regression equations and a surface equation at different temperatures. Result: The results showed that there was a strong positive correlation between the blood ORP values at different temperatures and the PMI. This study provides another example of using a three-dimensional surface equation as a tool to estimate the PMI at various temperature conditions.

  10. I.C. Engine emission reduction by copper oxide catalytic converter

    Science.gov (United States)

    Venkatesan, S. P.; Shubham Uday, Desai; Karan Hemant, Borana; Rajarshi Kushwanth Goud, Kagita; Lakshmana Kumar, G.; Pavan Kumar, K.

    2017-05-01

    The toxic gases emitted from diesel engines are more than petrol engines. Predicting the use of diesel engines, even more in future, this system is developed and can be used to minimize the harmful gases. Toxic gases include NOX, CO, HC and Smoke which are harmful to the atmosphere as well as to the human beings. The main aim of this work is to fabricate system, where the level of intensity of toxic gases is controlled through chemical reaction to more agreeable level. This system acts itself as an exhaust system; hence there is no needs to fit separate the silencer. The whole assembly is fitted in the exhaust pipe from engine. In this work, catalytic converter with copper oxide as a catalyst, by replacing noble catalysts such as platinum, palladium and rhodium is fabricated and fitted in the engine exhaust. With and without catalytic converter, the experimentations are carried out at different loads such as 0%, 25%, 50%, 75%, and 100% of maximum rated load. From the experimental results it is found that the maximum reduction is 32%, 61% and 21% for HC, NOx and CO respectively at 100% of maximum rated load when compared to that of without catalytic converter. This catalytic converter system is cash effective and more economical than the existing catalytic converter.

  11. Carbon dioxide reduction in a tubular solid oxide electrolysis cell for a carbon recycling energy system

    Energy Technology Data Exchange (ETDEWEB)

    Dipu, Arnoldus Lambertus, E-mail: dipu.a.aa@m.titech.ac.jp [Department of Nuclear Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Ujisawa, Yutaka [Nippon Steel and Sumitomo Metal Corporation, 16-1, Sunayama, Kamisu, Ibaraki 314-0255 (Japan); Ryu, Junichi; Kato, Yukitaka [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-22, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2014-05-01

    A new energy transformation system based on carbon recycling is proposed called the active carbon recycling energy system (ACRES). A high-temperature gas reactor was used as the main energy source for ACRES. An experimental study based on the ACRES concept of carbon monoxide (CO) regeneration via high-temperature reduction of carbon dioxide (CO{sub 2}) was carried out using a tubular solid oxide electrolysis cell employing Ni-LSM cermet|YSZ|YSZ-LSM as the cathode|electrolyte|anode. The current density increased with increasing CO{sub 2} concentration at the cathode, which was attributed to a decrease in cathode activation and concentration overpotential. Current density, as well as the CO and oxygen (O{sub 2}) production rates, increased with increasing operating temperature. The highest CO and O{sub 2} production rates of 1.24 and 0.64 μmol/min cm{sup 2}, respectively, were measured at 900 °C. Based on the electrolytic characteristics of the cell, the scale of a combined ACRES CO{sub 2} electrolysis/iron production facility was estimated.

  12. Improvement of electron emission characteristics of porous silicon emitter by using cathode reduction and electrochemical oxidation

    Science.gov (United States)

    Li, He; Wenjiang, Wang; Xiaoning, Zhang

    2017-03-01

    A new simple and convenient post-treat technique combined the cathode reduction (CR) and electrochemical oxidation (ECO) was proposed to improve the electron emission properties of the surface-emitting cold cathodes based on the porous silicon (PS). It is demonstrated here that by introducing this new technique combined CR and ECO, the emission properties of the diode have been significantly improved than those as-prepared samples. The experimental results showed that the emission current densities and efficiencies of sample treated by CR were 62 μA/cm2 and 12.10‰, respectively, nearly 2 orders of magnitude higher than those of as-prepared sample. Furthermore, the CR-treated PS emitter shows higher repeatability and stability compared with the as-prepared PS emitter. The scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive spectrometer (EDS), furier transformed infrared (FTIR) spectroscopy results indicated that the improved mechanism is mainly due to the passivation of the PS, which not only improve the PS morphology by the passivation of the H+ but also improve the uniformity of the oxygen content distribution in the whole PS layer. Therefore, the method combined the CR treatment and ECO is expected to be a valuable technique to enhance the electron emission characteristics of the PS emitter.

  13. Molybdenum Trihydride Complexes: Computational Model of Oxidatively Induced Reductive Elimination of Dihydrogen.

    Science.gov (United States)

    Szatkowski, Lukasz; Hall, Michael B

    2017-08-21

    Recent experimental work shows that the 18-electron molybdenum complexes (1,2,4-C5H2tBu3)Mo(PMe3)2H3 (Cp(tBu)MoH3) and (C5HiPr4)Mo(PMe3)2H3 (Cp(iPr)MoH3) undergo oxidatively induced reductive elimination of dihydrogen (H2), slowly forming the 15-electron monohydride species in tetrahydrofuran and acetonitrile. The 17-electron [Cp(tBu)MoH3](+) derivative was stable enough to be characterized by X-ray diffraction, while [Cp(iPr)MoH3](+) was not. Density functional theory calculations of the H2 elimination pathways for both complexes in the gas phase and in a continuum solvent model indicate that H2 elimination from [Cp(iPr)MoH3](+) has a lower barrier than that from [Cp(tBu)MoH3](+). Further, a specific solvent association, which is stronger for [Cp(tBu)MoH3](+) than for [Cp(iPr)MoH3](+), contributes to the stability of the former. In agreement with the experimental observations, the calculations predict that [Cp(tBu)MoH3](+) would be in a quartet state at room temperature and a doublet state at 4.2 K, while [Cp(iPr)MoH3](+) is in a doublet state even at room temperature.

  14. A Direct Transformation of Aryl Aldehydes to Benzyl Iodides Via Reductive Iodination

    Energy Technology Data Exchange (ETDEWEB)

    Ruso, Jayaraman Sembian; Rajendiran, Nagappan; Kumaran, Rajendran Senthil [Univ. of Madras, Chennai (India)

    2014-02-15

    A facile transformation of aryl aldehydes to benzyl iodides through one-pot reductive iodination is reported. This protocol displays remarkable functional group tolerance and the title compound was obtained in good to excellent yield.

  15. Research and Industrial Application of a Process for Direct Reduction of Molten High-Lead Smelting Slag

    Science.gov (United States)

    Li, Weifeng; Zhan, Jing; Fan, Yanqing; Wei, Chang; Zhang, Chuanfu; Hwang, Jiann-Yang

    2017-01-01

    A pyrometallurgical process for the direct reduction of molten high-lead smelting slag obtained by the Shuikoushan (SKS) method was reported in this article using solid anthracite as the fuel and reductant. The chemical composition, the lead phase composition, and the physical properties of the molten high-lead slag were examined. The effects of the process parameters on the recovery rate of valued metals were investigated in the laboratory. According to the experimental results, a new efficient bottom blow reduction furnace was employed in the pilot-scale test for high-lead slag reduction. The results showed the average recovery rate of lead was more than 96.0% with lower Pb and high Zn content of the reducing slag under the condition of reduction temperature 1100-1200°C, coal ratio 5.5-7.5%, reduction time 90-150 min, CaO/SiO2 ratio 0.35-0.45, and FeO/SiO2 ratio 1.4-1.55. Moreover, nearly 250 kg of standard coal per ton of crude Pb output was reduced compared with the blast furnace reduction process.

  16. Reduction efficiency prediction of CENIBRA's recovery boiler by direct minimization of gibbs free energy

    OpenAIRE

    W. L. Silva; Ribeiro,J. C. T.; E. F.da Costa Jr; A. O. S.da Costa

    2008-01-01

    The reduction efficiency is an important variable during the black liquor burning process in the Kraft recovery boiler. This variable value is obtained by slow experimental routines and the delay of this measure disturbs the pulp and paper industry customary control. This paper describes an optimization approach for the reduction efficiency determination in the furnace bottom of the recovery boiler based on the minimization of the Gibbs free energy. The industrial data used in this study were...

  17. Polydopamine-graphene oxide derived mesoporous carbon nanosheets for enhanced oxygen reduction

    Science.gov (United States)

    Qu, Konggang; Zheng, Yao; Dai, Sheng; Qiao, Shi Zhang

    2015-07-01

    Composite materials combining nitrogen-doped carbon (NC) with active species represent a paramount breakthrough as alternative catalysts to Pt for the oxygen reduction reaction (ORR) due to their competitive activity, low cost and excellent stability. In this paper, a simple strategy is presented to construct graphene oxide-polydopamine (GD) based carbon nanosheets. This approach does not need to modify graphene and use any catalyst for polymerization under ambient conditions, and the obtained carbon nanosheets possess adjustable thicknesses and uniform mesoporous structures without using any template. The thickness of GD hybrids and the carbonization temperature are found to play crucial roles in adjusting the microstructure of the resulting carbon nanosheets and, accordingly their ORR catalytic activity. The optimized carbon nanosheet generated by a GD hybrid of 5 nm thickness after 900 °C carbonization exhibits superior ORR activity with an onset potential of -0.07 V and a kinetic current density of 13.7 mA cm-2 at -0.6 V. The unique mesoporous structure, high surface areas, abundant defects and favorable nitrogen species are believed to significantly benefit the ORR catalytic process. Furthermore, it also shows remarkable durability and excellent methanol tolerance outperforming those of commercial Pt/C. In view of the physicochemical versatility and structural tunability of polydopamine (PDA) materials, our work would shed new light on the understanding and further development of PDA-based carbon materials for highly efficient electrocatalysts.Composite materials combining nitrogen-doped carbon (NC) with active species represent a paramount breakthrough as alternative catalysts to Pt for the oxygen reduction reaction (ORR) due to their competitive activity, low cost and excellent stability. In this paper, a simple strategy is presented to construct graphene oxide-polydopamine (GD) based carbon nanosheets. This approach does not need to modify graphene and use

  18. The Effect of Copper Loading on the Selective Catalytic Reduction of Nitric Oxide by Ammonia Over Cu-SSZ-13

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Ja Hun; Tran, Diana N.; Szanyi, Janos; Peden, Charles HF; Lee, Jong H.

    2012-03-01

    The effect of Cu loading on the selective catalytic reduction of NOx by NH3 was examined over 20-80% ion-exchanged Cu-SSZ-13 zeolite catalysts. High NO reduction efficiency (80-95%) was obtained over all catalyst samples between 250 and 500°C, and the gas hourly space velocity of 200,000 h-1. Both NO reduction and NH3 oxidation activities under these conditions were found to increase slightly with increasing Cu loading at low temperatures. However, NO reduction activity was suppressed with increasing Cu loadings at high temperatures (>500oC) due to excess NH3 oxidation. The optimum Cu ion exchange level appears to be ~40-60% as higher than 80% NO reduction efficiency was obtained over 50% Cu ion-exchanged SSZ-13 up to 600oC. The NO oxidation activity of Cu-SSZ-13 was found to be low regardless of Cu loading, although it was somewhat improved with increasing Cu ion exchange level at high temperatures. During the “fast” SCR (i.e., NO/NO2 =1), only a slight improvement in NOx reduction activity was obtained for Cu-SSZ-13. Regardless of Cu loading, near 100% selectivity to N2 was observed; only a very small amount of N2O was produced even in the presence of NO2. Based on the Cu loading, the apparent activation energies for NO oxidation and NO SCR were estimated to be ~58 kJ/mol and ~41 kJ/mol, respectively.

  19. Identifying active surface phases for metal oxide electrocatalysts: a study of manganese oxide bi-functional catalysts for oxygen reduction and water oxidation catalysis

    DEFF Research Database (Denmark)

    Su, Hai-Yan; Gorlin, Yelena; Man, Isabela Costinela

    2012-01-01

    Progress in the field of electrocatalysis is often hampered by the difficulty in identifying the active site on an electrode surface. Herein we combine theoretical analysis and electrochemical methods to identify the active surfaces in a manganese oxide bi-functional catalyst for the oxygen...... and that its overpotential is highly dependent on the stabilization of intermediates through hydrogen bonds with water molecules. We also determine that OER occurs through direct recombination mechanism and that its major source of overpotential is the scaling relationship between HOO* and HO* surface...... intermediates. Using a previously developed Sabatier model we show that the theoretical predictions of catalytic activities match the experimentally determined onset potentials for the ORR and the OER, both qualitatively and quantitatively. Consequently, the combination of first-principles theoretical analysis...

  20. Direct patterning of complex oxides by pulsed laser deposition through stencils

    Energy Technology Data Exchange (ETDEWEB)

    Riele, Paul te; Janssens, Arjen; Rijnders, Guus; Blank, Dave H A [University of Twente, Inorganic Material Science, Faculty of Science and Technology MESA Institute for Nanotechnology, PO Box 217, 7500 AE Enschede (Netherlands)

    2007-04-15

    The possibilities to grow isolated structures of complex oxides by pulsed laser deposition through stencils were investigated. A stencil consisting of a SiN membrane with apertures of several hundred nanometers embedded in a Si chip is placed in front of a heated substrate (up to 750 degrees Celsius). Deposition through these apertures results in resistless, direct patterning by local deposition of complex oxides like ferroelectric Lead Zirconate Titanate. The created isolated structures were analyzed by AFM imaging. Under-deposition, in this work called broadening, is inevitable during stencil deposition and is depending on deposition parameters, especially pressure. Different causes of broadening are mapped and discussed.