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Sample records for vanadium oxide lvo

  1. Catalytic oxidations by vanadium complexes

    NARCIS (Netherlands)

    Ligtenbarg, A.G J; Hage, R.; Feringa, B.L.

    Vanadium haloperoxidases catalyse the oxidation of halides leading to halogenation of substrates or, in the absence of suitable substrates, to oxidation of hydrogen peroxide into singlet oxygen and water. Furthermore, V-haloperoxidases are capable to give enantioselective sulfoxidation under the

  2. Vanadium

    OpenAIRE

    Pourret, Olivier; Dia, Aline

    2017-01-01

    International audience; Vanadium (chemical symbol, V) is a d-block transition metal,silver in color, appearing in the first long period of the peri-odic table between titanium and chromium. Vanadium hastwo stable isotopes: 50V and 51V, with atomic abundance of0.25 % and 99.75 %, respectively. Vanadium has several oxidation forms (between 2+ and 5+). In the lithosphere, Voccurs as reducing V(III) form, whereas in oxidizing con- ditions V prevails under V(IV) form. Vanadium(II) is partic- ularl...

  3. Lithium insertion in sputtered vanadium oxide film

    DEFF Research Database (Denmark)

    West, K.; Zachau-Christiansen, B.; Skaarup, S.V.

    1992-01-01

    were oxygen deficient compared to V2O5. Films prepared in pure argon were reduced to V(4) or lower. The vanadium oxide films were tested in solid-state lithium cells. Films sputtered in oxygen showed electrochemical properties similar to crystalline V2O5. The main differences are a decreased capacity...

  4. Vanadium

    Science.gov (United States)

    Kelley, Karen D.; Scott, Clinton T.; Polyak, Désirée E.; Kimball, Bryn E.; Schulz, Klaus J.; DeYoung, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    sands, and oil shales may be important future sources.Vanadium occurs in one of four oxidation states in nature: +2, +3, +4, and +5. The V3+ ion has an octahedral radius that is almost identical to that of (Fe3+) and (Al3+) and, therefore, it substitutes in ferromagnesian minerals. During weathering, much of the vanadium may partition into newly formed clay minerals, and it either remains in the +3 valence state or oxidizes to the +4 valence state, both of which are relatively insoluble. If erosion is insignificant but chemical leaching is intense, the residual material may be enriched in vanadium, as are some bauxites and laterites. During the weathering of igneous, residual, or sedimentary rocks, some vanadium oxidizes to the +5 valence state, especially in the intensive oxidizing conditions that are characteristic of arid climates.The average contents of vanadium in the environment are as follows: soils [10 to 500 parts per million (ppm)]; streams and rivers [0.2 to 2.9 parts per billion (ppb)]; and coastal seawater (0.3 to 2.8 ppb). Concentrations of vanadium in soils (548 to 7,160 ppm) collected near vanadium mines in China, the Czech Republic, and South Africa are many times greater than natural concentrations in soils. Additionally, if deposits contain sulfide minerals such as chalcocite, pyrite, and sphalerite, high levels of acidity may be present if sulfide dissolution is not balanced by the presence of acid-neutralizing carbonate minerals. Some of the vanadium-bearing deposit types, particularly some SSV and black-shale deposits, contain appreciable amounts of carbonate minerals, which lowers the acid-generation potential.Vanadium is a micronutrient with a postulated requirement for humans of less than 10 micrograms per day, which can be met through dietary intake. Primary and secondary drinking water regulations for vanadium are not currently in place in the United States. Vanadium toxicity is thought to result from an intake of more than 10 to 20 milligrams

  5. Partial Oxidation of n-Pentane over Vanadium Phosphorus Oxide ...

    African Journals Online (AJOL)

    The selective oxidation of n-pentane to value-added products, maleic anhydride or phthallic anhydride by vanadium phosphorus oxide loaded on hydroxyapatites as catalysts and oxygen as oxidant was investigated. Hydroxyapatite (HAp) and cobalthydroxyapatite (Co-HAp) were prepared by the co-precipitation method ...

  6. Modified lithium vanadium oxide electrode materials products and methods

    Science.gov (United States)

    Thackeray, Michael M.; Kahaian, Arthur J.; Visser, Donald R.; Dees, Dennis W.; Benedek, Roy

    1999-12-21

    A method of improving certain vanadium oxide formulations is presented. The method concerns fluorine doping formulations having a nominal formula of LiV.sub.3 O.sub.8. Preferred average formulations are provided wherein the average oxidation state of the vanadium is at least 4.6. Herein preferred fluorine doped vanadium oxide materials, electrodes using such materials, and batteries including at least one electrode therein comprising such materials are provided.

  7. Vanadium Oxidation State Determination by X-Ray Absorption Spectroscopy

    Science.gov (United States)

    Duchesne, Marc A.; Nakano, Jinichiro; Hu, Yongfeng; MacLennan, Aimee; Hughes, Robin W.; Bennett, James; Nakano, Anna

    Vanadium is found in slags produced during metal refinement and fossil fuel combustion/gasification. The oxidation state of vanadium in slag has technological and environmental implications. For example, it may affect slag flow and refractory wear inside reactors, as well as leachability and toxicity of industrial by-products. Determination of vanadium's oxidation state in crystalline phases can be achieved via the widely adopted X-ray diffraction (XRD) technique. However, this technique does not provide information on vanadium in amorphous phases. The objective of this research is to determine the oxidation state of vanadium in petroleum coke gasification samples and laboratory samples using X-ray absorption spectroscopy (XAS) with Canadian Light Source's soft X-ray micro-characterization beamline (SXRMB). Linear combination fitting of XAS spectra with reference samples allowed quantitative determination of vanadium speciation.

  8. Hydrothermal Synthesis of Nanostructured Vanadium Oxides

    Directory of Open Access Journals (Sweden)

    Jacques Livage

    2010-08-01

    Full Text Available A wide range of vanadium oxides have been obtained via the hydrothermal treatment of aqueous V(V solutions. They exhibit a large variety of nanostructures ranging from molecular clusters to 1D and 2D layered compounds. Nanotubes are obtained via a self-rolling process while amazing morphologies such as nano-spheres, nano-flowers and even nano-urchins are formed via the self-assembling of nano-particles. This paper provides some correlation between the molecular structure of precursors in the solution and the nanostructure of the solid phases obtained by hydrothermal treatment.

  9. Platinum-Vanadium Oxide Nanotube Hybrids

    Science.gov (United States)

    Mello, Filipe L. S.; Costa, Lídia O. O.; Hernández, Eduardo Padrón; de Farias, Andréa M. Duarte; Fraga, Marco A.

    2010-06-01

    The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H2PtCl6 is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6-7 nm.

  10. Platinum–Vanadium Oxide Nanotube Hybrids

    Directory of Open Access Journals (Sweden)

    Hernández EduardoPadrón

    2010-01-01

    Full Text Available Abstract The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H2PtCl6 is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6–7 nm.

  11. Extraction of vanadium from vanadium slag by high pressure oxidative acid leaching

    Science.gov (United States)

    Zhang, Guo-quan; Zhang, Ting-an; Lü, Guo-zhi; Zhang, Ying; Liu, Yan; Liu, Zhuo-lin

    2015-01-01

    To extract vanadium in an environment friendly manner, this study focuses on the process of leaching vanadium from vanadium slag by high pressure oxidative acid leaching. Characterizations of the raw slag, mineralogy transformation, and the form of leach residues were made by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The result shows that the vanadium slag is composed of major phases of fayalite, titanomagnetite, and spinel. During the high pressure oxidative acid leaching process, the fayalite and spinel phases are gradually decomposed by sulfuric acid, causing the release of vanadium and iron in the solution. Meanwhile, unreacted silicon and titanium are enriched in the leach residues. With the initial concentration of sulfuric acid at 250 g·L-1, a leaching temperature of 140°C, a leaching time of 50 min, a liquid-solid ratio of 10:1 mL·g-1, and oxygen pressure at 0.2 MPa, the leaching rate of vanadium reaches 97.69%.

  12. High Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries

    Science.gov (United States)

    2015-04-24

    Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries Siu on Tung, Krista L. Hawthorne, Yi Ding, James Mainero, and Levi T. Thompson...Automotive Research Development and Engineering Center, Warren, MI 48387, USA Keywords: nanostructured materials, lithium ion batteries , cathode...2014 to 00-00-2015 4. TITLE AND SUBTITLE High Performance Pillared Vanadium Oxide Cathode for Lithium Ion Batteries 5a. CONTRACT NUMBER 5b. GRANT

  13. Novel vanadium phosphate phases as catalysts for selective oxidation

    Indian Academy of Sciences (India)

    Unknown

    important vanadium phosphate phases used as selective oxidation catalysts, it has been observed that ... molybdenum oxides are the most widely used ones for the selective oxidation of alkanes. Amongst these the ... pentane to maleic and pthalic anhydride, and in the oxidative dehydrogenation of ethane, propane etc 4.

  14. Conceptual chemistry approach towards the support effect in supported vanadium oxides: valence bond calculations on the ionicity of vanadium catalysts

    NARCIS (Netherlands)

    Fievez, T.; De Proft, F.; Geerlings, P.; Weckhuysen, B.M.; Havenith, R.W.A.

    2011-01-01

    The concept of bond ionicity, obtained via a valence bond analysis, is invoked in the interpretation of the catalytic activity of supported vanadium oxides, in analogy with previous work conducted within the framework of conceptual DFT. For a set of model clusters representing the vanadium oxide

  15. Conceptual chemistry approach towards the support effect in supported vanadium oxides : Valence bond calculations on the ionicity of vanadium catalysts

    NARCIS (Netherlands)

    Fievez, Tim; De Proft, Frank; Geerlings, Paul; Weckhuysen, Bert M.; Havenith, Remco W. A.

    2011-01-01

    The concept of bond ionicity, obtained via a valence bond analysis, is invoked in the interpretation of the catalytic activity of supported vanadium oxides, in analogy with previous work conducted within the framework of conceptual DFT. For a set of model clusters representing the vanadium oxide

  16. Vanadium Doped Tungsten Oxide Material - Electrical Physical and Sensing Properties

    Directory of Open Access Journals (Sweden)

    Shishkin N. Y.

    2008-05-01

    Full Text Available The electrical physical and sensing (to VOCs and inorganic gases properties of vanadium doped tungsten oxide in the regions of phase transition temperature were investigated. Vanadium oxide (II dimerization was observed in the doped material, corresponding to new phase transition. The extreme sensitivity and selectivity to chemically active gases and vapors in small concentrations: CO, NOx, NH3 acetone, ethanol near phase transitions temperature was found. Sensor elements were manufactured for the quantitative detection (close to 1 ppm of alcohol and ammonia.

  17. THE INFLUENCE OF NIOBIUM ON THE ACIDITY AND STRUCTURE OF GAMMA-ALUMINA-SUPPORTED VANADIUM OXIDES

    Directory of Open Access Journals (Sweden)

    Sathler M.N.B.

    1998-01-01

    Full Text Available Gamma-alumina-supported niobium oxide was used as a support for vanadium oxides. The influence of the addition of niobium oxide was studied by looking for changes in the structure and acid-base character of superficial species. Vanadium oxide was deposited using the continuous adsorption method; niobium oxide was impregnated using the incipient wetness method. The catalysts were characterized by XPS, UV-visible and IR spectroscopy. Catalytic tests were performed using propane oxidation reaction at 400oC. For coverage below the monolayer, both vanadium and niobium oxides were observed in slightly condensed superficial species. The presence of vanadium oxide on the support was found to increase the Lewis acidity and create some Bronsted acidity. Higher catalytic activity and selectivity for propene were associated with vanadium oxides. The presence of niobium did not contribute to the modification of the chemical properties of superficial vanadium but did decrease the adsorption of vanadium on the alumina.

  18. Novel hybrid materials based on the vanadium oxide nanobelts

    Energy Technology Data Exchange (ETDEWEB)

    Zabrodina, G.S., E-mail: kudgs@mail.ru [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Makarov, S.G.; Kremlev, K.V. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Yunin, P.A.; Gusev, S.A. [Institute for Physics of Microstructures Russian Academy of Sciences, Nizhny Novgorod 603087 (Russian Federation); Kaverin, B.S.; Kaverina, L.B. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Ketkov, S.Yu. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation)

    2016-04-15

    Graphical abstract: - Highlights: • Flat and curved vanadium oxide nanobelts have been synthesized. • Hybrid material was prepared via decoration of flexible nanobelts with zinc phthalocyanine. • Investigations of the thermal stability, morphologies and structures were carried out. - Abstract: Novel hybrid materials based on zinc phthalocyanine and nanostructured vanadium oxides have attracted extensive attention for the development of academic research and innovative industrial applications such as flexible electronics, optical sensors and heterogeneous catalysts. Vanadium oxides nanobelts were synthesized via a hydrothermal treatment V{sub 2}O{sub 5}·nH{sub 2}O gel with surfactants (TBAB, CTAB) used as structure-directing agents, where CTAB – cetyltrimethylammonium bromide, TBAB – tetrabutylammonium bromide. Hybrid materials were prepared decoration of (CTA){sub 0.33}V{sub 2}O{sub 5} flexible nanobelts with cationic zinc phthalocyanine by the ion-exchange route. Investigations of the thermal stability, morphologies and structures of the (CTA){sub 0.33}V{sub 2}O{sub 5}, (TBA){sub 0.16}V{sub 2}O{sub 5} nanobelts and zinc phthalocyanine exchange product were carried out. The hybrid materials based on the nanostructured vanadium oxide and zinc phthalocyanine were tested as photocatalysts for oxidation of citronellol and 2-mercaptoethanol by dioxygen.

  19. Chemistry, spectroscopy and the role of supported vanadium oxides in heterogeneous catalysis

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Keller, D.E.

    2003-01-01

    Supported vanadium oxide catalysts are active in a wide range of applications. In this review, an overview is given of the current knowledge available about vanadium oxide-based catalysts. The review starts with the importance of vanadium in heterogeneous catalysis, a discussion of the molecular

  20. Vanadium oxide/polypyrrole aerogel nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Dave, B.C.; Dunn, B.S.; Wong, H.P. [Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering; Leroux, F.; Nazar, L.F. [Univ. of Waterloo, Ontario (Canada). Dept. of Chemistry

    1996-12-31

    Vanadium pentoxide/polypyrrole aerogel (ARG) nanocomposites were prepared by hydrolysis of VO(OC{sub 3}H{sub 7}){sub 3} using pyrrole/water/acetone mixtures. Monolithic green-black gels with polypyrrole/V ratios ranging from 0.15 to 1.0 resulted from simultaneously polymerization of the pyrrole and vanadium alkoxide precursors. Supercritical drying yielded high surface (150--200 m{sup 2}/g) aerogels, of sufficient mechanical integrity to allow them to be cut without fracturing. TEM studies of the aerogels show that they are comprised of fibers similar to that of V{sub 2}O{sub 5} ARG`s, but with a much shorter chain length. Evidence from IR that the inorganic and organic components strongly interact leads them to propose that this impedes the vanadium condensation process. The result is ARG`s that exhibit decreased electronic conductivity with increasing polymer content. Despite the unexpected deleterious effect of the conductive polymer on the bulk conductivity, at low polymer content, the nanocomposite materials show enhanced electrochemical properties for Li insertion compared to the pristine aerogel.

  1. Rechargeable lithium cells with modified vanadium oxide cathodes

    Science.gov (United States)

    Chung, S. K.; Chmilenko, N. A.; Borovykov, A. Ya; Lee, S. H.

    Modified vanadium oxide has been prepared by melting V 2O 5 with additives of 3-3.5% of sodium orthosilicate at 690°C for 3 h followed by fast cooling to an ambient temperature. Charge-discharge characteristics of this oxide were studied as an active cathode material for lithium secondary batteries. The oxide undergoes irreversible transition to become essentially amorphous after first discharge to cut-off voltage of 2 V vs. Li, and then exhibits excellent rechargeability in the 1.5 to 3.9 V potential range. The coin type 2325 size secondary cells have been manufactured and tested with the modified vanadium oxide cathodes and Li-Al alloy anodes. Preliminary shallow cycling modifies the cells' performance and allows to obtain rating capacity 50 mA h in the voltage diapason of 2.0-3.9 V with draining current 0.5 mA.

  2. Crossing points in the electronic band structure of vanadium oxide

    Directory of Open Access Journals (Sweden)

    Keshav N. Shrivastava

    2010-03-01

    Full Text Available The electronic band structures of several models of vanadium oxide are calculated. In the models 1-3, every vanadium atom is connected to 4 oxygen atoms and every oxygen atom is connected to 4 vanadium atoms. In model 1, a=b=c 2.3574 Å; in model 2, a= 4.7148 Å, b= 2.3574 Å and c= 2.3574 Å; and in model 3, a= 4.7148 Å, b= 2.3574 Å and c= 4.7148 Å. In the models 4-6, every vanadium atom is connected to 4 oxygen atoms and every oxygen atom is connected to 2 vanadium atoms. In model 4, a=b= 4.551 Å and c= 2.851 Å; in model 5, a=b=c= 3.468 Å; and in model 6, a=b=c= 3.171 Å. We have searched for a crossing point in the band structure of all the models. In model 1 there is a point at which five bands appear to meet but the gap is 7.3 meV. In model 2 there is a crossing point between G and F points and there is a point between F and Q with the gap ≈ 3.6608 meV. In model 3, the gap is very small, ~ 10-5 eV. In model 4, the gap is 5.25 meV. In model 5, the gap between Z and G points is 2.035 meV, and in model 6 the gap at Z point is 4.3175 meV. The crossing point in model 2 looks like one line is bent so that the supersymmetry is broken. When pseudopotentials are replaced by a full band calculation, the crossing point changes into a gap of 2.72 x 10-4 eV.

  3. Study of propane partial oxidation on vanadium-containing catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

  4. Preparation, characterization, and electrochemical properties of lithium vanadium oxide nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Zhuo Shujuan [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123 (China); Anhui Key Laboratory of Functional Molecular Solids, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Shao Mingwang, E-mail: mwshao@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123 (China); Zhou Qing; Liao Fan [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123 (China)

    2011-07-15

    Graphical abstract: Display Omitted Highlights: > The lithium ions can easily move between the layers of lithium vanadium oxide. > It can highly increase the electron transfer between the electrode and dopamine. > The reversibility of electrochemical process was significantly improved. - Abstract: Highly uniform lithium vanadium oxide nanoribbons were successfully prepared in large quantities using a facile hydrothermal approach without employing any surfactants or templates. The as-prepared products were up to hundreds of micrometers in length, about 200 nm in width, and 20 nm in thickness. These nanoribbons and nafion composite were employed to modify glassy carbon electrode, which displayed excellent electrochemical sensitivity and rapid response in detecting dopamine in phosphate buffer solution. Lithium ions can greatly increase the electron transfer between the electrode and biological materials, and significantly increase the reversibility of electrochemical process. A linear relationship between the concentrations of dopamine and its oxidation peak currents was obtained. The linear range for the detection of dopamine was 2.0 x 10{sup -6} to 1.0 x 10{sup -4} M with a detection limit of 1.0 x 10{sup -7} M. In addition, the good reproducibility and long-term stability of the sensor make it valuable for further application.

  5. Sulfur-vanadium oxide gel composites as thin film cathodes for rechargeable lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S.P.; Gavrilov, A.B.; Skotheim, T.A.

    1998-07-01

    A class of novel electroactive cathode materials based on composites produced from elemental sulfur and vanadium oxide xerogels or aerogels has been developed as models for lithium battery applications. The use of elemental sulfur in rechargeable lithium batteries has been hindered due to certain limitations such as, very low electronic conductivity and the out-diffusion of polysulfides during the cycling process which reduces the cycling efficiency. Vanadium oxide xerogels and aerogels have certain desirable characteristic physico-chemical properties, such as, high surface areas with nono-scale interconnecting porosity, high electronic conductivity, non- or nanocrystallinity, and oxidation reduction catalytic activity. Since these properties may improve the performance of sulfur based rechargeable batteries, a family of composite cathodes containing elemental sulfur and vanadium oxide gels were produced. The performance of the composites cathodes, in thin film form, were evaluated in coin cells and AA cells with metallic lithium anodes and liquid electrolytes. The multifunctional role of vanadium oxide gels on the cell performance of the cells having composite cathodes has been qualitatively explored. Results indicate that the cathodes having xerogel composites based on vanadium oxide sol from vanadium oxide isopropoxide can be made with high sulfur content (80 wt %) and with low carbon content (5 wt %) and without any polymer binder. This shows the contribution of adhesive properties and electronic conductivity of vanadium oxide xerogels. A significant suppression of polysulfide out-diffusion is observed with appropriate processing of the composite cathodes. It is anticipated that the nanoscale interconnecting porosity of gels plays an important role in this behavior. An excellent rate capability is observed with the vanadium-oxide sulfur composite cathodes indicating the contribution of intrinsic electrochemical properties of the vanadium oxide.

  6. Directed synthesis of bio-inorganic vanadium oxide composites using genetically modified filamentous phage

    Science.gov (United States)

    Mueller, Michael; Baik, Seungyun; Jeon, Hojeong; Kim, Yuchan; Kim, Jungtae; Kim, Young Jun

    2015-05-01

    The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V2O5 precursor. Using the genetic modification of the bacteriophage, we displayed two cysteines that constrained the RSTB-1 peptide on the major coat protein P8, resulting in vanadium oxide crystallization. The phage-driven vanadium oxide crystals with different topologies, microstructures, photodegradation and vanadium oxide composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz microbalance and dissipation (QCM-D) and X-ray photoelectron spectroscopy (XPS). Non-specific electrostatic attraction between a wild-type phage (wt-phage) and vanadium cations in the V2O5 precursor caused phage agglomeration and fiber formation along the length of the viral scaffold. As a result, the addition of recombinant phage (re-phage) in V2O5 precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/VxOx composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V2O5 composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of a mineralizing aid, such as the two cysteine-constrained peptides on the phage surface, and has potential for use in nanotechnology applications.

  7. Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

    Directory of Open Access Journals (Sweden)

    Juan M. Salazar

    2013-01-01

    Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

  8. Processing, characterization, and bactericidal activity of undoped and silver-doped vanadium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tousley, M.E.; Wren, A.W.; Towler, M.R. [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States); Mellott, N.P., E-mail: mellott@alfred.edu [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States)

    2012-12-14

    Vanadium oxide (V) and silver-doped vanadium oxide (Ag-V) powders were prepared via sol-gel processing. Structural evolution and bactericidal activity was examined as a function of temperature ranging from 250, 350, 450 and 550 Degree-Sign C. Powders were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. Results from all techniques showed vanadium pentoxide (V{sub 2}O{sub 5}) is the predominant phase regardless of heat treatment temperature or the addition of silver (Ag). XRD analysis suggests Ag is present as AgCl in samples heat treated to 250, 350, and 450 Degree-Sign C and as AgV{sub 6}O{sub 15} at 550 Degree-Sign C. Bactericidal activity was evaluated against Escherichia coli using the agar disk diffusion method considering both Ag-V and undoped, V powders. While the addition of Ag significantly increased bactericidal properties, the specific Ag valency, or crystal structure and morphology formed at higher temperatures, had little effect on functionality. -- Highlights: Black-Right-Pointing-Pointer Vanadium and silver-doped vanadium oxide powders were prepared via sol-gel. Black-Right-Pointing-Pointer Powders were characterized using advanced, complementary structural techniques. Black-Right-Pointing-Pointer Bactericidal activity was evaluated against E. coli. Black-Right-Pointing-Pointer Both vanadium and silver doped vanadium oxide show bactericidal activity.

  9. On oxygen chemisorption for characterization of silica-supported vanadium oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Faraldos, M.; Banares, M.A.; Fierro, J.L.G. [Instituto de Catalysis y Petroleoquimica, Madrid (Spain)] [and others

    1997-05-01

    Oxygen chemisorption experiments on prereduced silica- supported vanadia catalysts have been performed in order to determine the optimum conditions for measuring the relative dispersion of vanadium oxide on the silica substrate. By following the extent of vanadia reduction microgravimetrically, it is shown that an appropriate prereduction of the catalyst at 823 K under hydrogen is fundamental in obtaining a reproducible well-defined stoichiometrically reduced vanadium oxide system (V{sup 3+}). AT 643 K the reduction process is very much slower and requires very long times in order to approach a plateau. Measurement of the binding energies of the V{sub 2}p{sub 3/2} core level spectra indicates that high-temperature oxygen chemisorption (643 K) results in a reoxidation of the prereduced vanadium oxide species within crystallites leading to an overestimation of the number of exposed vanadium sites. Chemisorption at low temperatures (298 or 195 K) does not affect the stoichiometrically reduced vanadium oxide species within crystallites, thus allowing the number of exposed surface vanadium sites to be measured. 25 refs., 5 figs., 1 tab.

  10. Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

    2010-07-01

    V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

  11. Sputter-deposited low reflectance vanadium oxide-molybdenum oxide thin films on silicon

    Science.gov (United States)

    Nayak, Manish Kumar; Esther, A. Carmel Mary; Bera, Parthasarathi; Dey, Arjun

    2017-09-01

    A single layer antireflective, smart, crystalline and nanocolumnar pulsed RF magnetron sputtered vanadium oxide-molybdenum oxide thin film on silicon is proposed for the alternate antireflective material for silicon based futuristic solar cell application. The VO-MO film with 130 nm thickness grown at 200 W shows significant low reflectance (1% within the 500-600 nm region). The VO-MO film with lowest reflectance shows a phase transition at around 55 °C which is beneficial due to film inherent variable IR emittance behaviour which may be helpful for eliminating excess heat load generated during in-service of silicon solar cell.

  12. Study of the kinetic behavior of mandelic acid oxidation by vanadium(V in sulfuric acid medium: effect of CTAB presence

    Directory of Open Access Journals (Sweden)

    Rômulo Augusto Ando

    2006-02-01

    Full Text Available The mandelic acid oxidation by vanadium (V in sulfuric acid medium was studied at 303 K. The reaction rate was determined spectrophotometrically by means of the formation of vanadium (IV at 760 nm. The oxidation reaction showed first order dependence in terms of vanadium (VThe mandelic acid oxidation by vanadium (V in sulfuric acid medium was studied at 303 K. The reaction rate was determined spectrophotometrically by means of the formation of vanadium (IV at 760 nm. The oxidation reaction showed first order dependence in terms of vanadium (V.

  13. Investigating the air oxidation of V(II) ions in a vanadium redox flow battery

    Science.gov (United States)

    Ngamsai, Kittima; Arpornwichanop, Amornchai

    2015-11-01

    The air oxidation of vanadium (V(II)) ions in a negative electrolyte reservoir is a major side reaction in a vanadium redox flow battery (VRB), which leads to electrolyte imbalance and self-discharge of the system during long-term operation. In this study, an 80% charged negative electrolyte solution is employed to investigate the mechanism and influential factors of the reaction in a negative-electrolyte reservoir. The results show that the air oxidation of V(II) ions occurs at the air-electrolyte solution interface area and leads to a concentration gradient of vanadium ions in the electrolyte solution and to the diffusion of V(II) and V(III) ions. The effect of the ratio of the electrolyte volume to the air-electrolyte solution interface area and the concentrations of vanadium and sulfuric acid in an electrolyte solution is investigated. A higher ratio of electrolyte volume to the air-electrolyte solution interface area results in a slower oxidation reaction rate. The high concentrations of vanadium and sulfuric acid solution also retard the air oxidation of V(II) ions. This information can be utilized to design an appropriate electrolyte reservoir for the VRB system and to prepare suitable ingredients for the electrolyte solution.

  14. Vanadium oxide nanotubes as cathode material for Mg-ion batteries

    DEFF Research Database (Denmark)

    Christensen, Christian Kolle; Sørensen, Daniel Risskov; Bøjesen, Espen Drath

    Vanadium oxide compounds as cathode material for secondary Li-ion batteries gained interest in the 1970’s due to high specific capacity (>250mAh/g), but showed substantial capacity fading.1 Developments in the control of nanostructured morphologies have led to more advanced materials, and recently...... vanadium oxide nanotubes (VOx-NT) were shown to perform well as a cathode material for Mg-ion batteries.2 The VOx-NTs are easily prepared via a hydrothermal process to form multiwalled scrolls of VO layer with primary amines interlayer spacer molecules.3 The tunable and relative large layer spacing 1-3 nm...... synchrotron powder X-ray diffraction measured during battery operation. These results indicate Mg-intercalation in the multiwalled VOx-NTs occurs within the space between the individual vanadium oxide layers while the underlying VOx frameworks constructing the walls are affected only to a minor degree...

  15. ESR study of deoxygenated and oxidated forms of vanadium(4) porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Selyutin, G.E.; Shklyaev, A.A. (AN SSSR, Krasnoyarsk. Inst. Khimii i Khimicheskoj Tekhnologii)

    1982-01-01

    Halogenated and oxidated forms of porphyrins of oxovanadium VOP (ethioporphyrin-EP and tetraphenylporphyrin) with different halides are studied using the ESR method. In reactions of vanadylporphyrins with metal halides deoxygenation of vanadyl ion is realized and octahedral complex of dihalogenovanadium (4) of porphyrin (P) are formed and at the intermediate stage bimetal complex of vanadiumporphyrin with halide is formed, in which halide cation is bonded by means of the bridge oxygen atom with vanadium ion. In dihalide complexes VX/sub 2//sup -/P for vanadium (4) ion a regular octahedral surrounding is realized and the axis of tetragonal distortion can be oriented both in perpendicular and lay in porphyrin plane. The oxidated forms, formed during oxidation in the presence of halides, present dihalide vanadium (4) complexes with mono- and dication of porphyrin ligand.

  16. Vanadium oxide thin films deposited on silicon dioxide buffer layers by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Chen Sihai [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China) and Wuhan National laboratory for Optoelectronics, Wuhan 430074 (China)]. E-mail: cshai99@yahoo.com; Ma Hong [Department of Electronics and Information Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wang Shuangbao [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Shen Nan [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Xiao Jing [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhou Hao [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhao Xiaomei [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wuhan National laboratory for Optoelectronics, Wuhan 430074 (China); Li Yi [Department of Optoelectronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); State Key Laboratory for Imaging Recognization and Intelligence Control, Huazhong University of Science and Technology, Wuhan 430074 (China); Yi Xinjian [State Key Laboratory for Imaging Recognization and Intelligence Control, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2006-02-21

    Thin films made by vanadium oxide have been obtained by direct current magnetron sputtering method on SiO{sub 2} buffer layers. A detailed electrical and structural characterization has been performed on the deposited films by four-point probe method and scanning electron microscopy (SEM). At room temperature, the four-point probe measurement result presents the resistance of the film to be 25 kU/sheet. The temperature coefficient of resistance is - 2.0%/K. SEM image indicates that the vanadium oxide exhibits a submicrostructure with lamella size ranging from 60 nm to 300 nm. A 32 x 32-element test microbolometer was fabricated based on the deposited thin film. The infrared response testing showed that the response was 200 mV. The obtained results allow us to conclude that the vanadium oxide thin films on SiO{sub 2} buffer layers is suitable for uncooled focal plane arrays applications.

  17. Theoretical study of vanadium oxides interaction with Y-zeolite.

    Science.gov (United States)

    Arroyo, M; Sansores, L E; Salcedo, R; Montoya, J A

    2008-12-01

    A current problem about oils and feedstock in fluid catalytic cracking (FCC) is the continuous cumulative deposition of metal contaminants on the catalyst, resulting in important modifications of its properties. Vanadium plays a detrimental role on the catalyst components because enhances the destruction of the Y-zeolite structure during regeneration stage when it is exposed by steam and oxygen at high temperatures. Knowledge of the mechanism interaction of vanadium with the catalyst is important to improve FCC performance. Quantum Molecular Dynamics calculations were done introducing the VO, V2O3, VO2 or V2O5 molecules at the center of a Y-zeolite ring simulating regeneration conditions. The results indicate that the principal reaction is carried out among the zeolite and the vanadium atoms of molecules. This happens, when interaction is presented, since the loss of a hydrogen atom of the active place causes high degree of oxygen reactivity.

  18. Nature of active vanadium nanospecies in MCM-41 type catalysts for olefins oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Chanquía, Corina M., E-mail: cchanquia@cab.cnea.gov.ar [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Cánepa, Analía L. [Centro de Investigación y Tecnología Química (CITeQ), Universidad Tecnológica Nacional, Facultad Regional Córdoba (UTN-FRC), Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016, Córdoba Capital (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Winkler, Elin L. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); and others

    2016-06-01

    A multi-technique physicochemical investigation including UV–Vis-DRS, Raman spectroscopy, XPS, ESR and FTIRS with pyridine adsorption was performed to analyze the nature of different vanadium nanospecies present on MCM-41 type catalysts. By employing a direct hydrothermal synthesis, vanadium species were incorporated into siliceous structure mainly as tetrahedrally coordinated isolated V{sup δ+} ions, which would be located inside the wall and on the wall surface of the mesoporous channels. The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was also revealed. Acidity measurements permitted to infer about the majority presence of Lewis acid sites, which increase with vanadium content. The catalytic performance of these materials was evaluated in the reaction of α-pinene oxidation with H{sub 2}O{sub 2}. The highest intrinsic activity of the sample with lower V loading was attributed to the high dispersion and efficiency of the isolated V{sup δ+} species that actuate as active sites. A mixture of reaction products arising from competitive processes of epoxidation and allylic oxidation was found. - Highlights: • Nature of vanadium nanospecies in mesoporous silicates was investigated. • From hydrothermal sol–gel synthesis, isolated V{sup δ+} sites were mainly generated. • The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was revealed. • The catalytic performance was evaluated in α-pinene oxidation with H{sub 2}O{sub 2}. • The high catalytic activity is attributed to high dispersion of isolated V{sup δ+} ions.

  19. Geochemical behaviour of vanadium in iron—titanium oxides

    NARCIS (Netherlands)

    Schuiling, R.D.; Feenstra, A.

    The following geochemical rules-of-thumb seem to hold for vanadium: 1. (1) Magnetites as a group have higher V contents than either hematites or ilmenites. 2. (2) In magnetite—hematite pairs, however, the hematite has the higher V content. 3. (3) In magnetite—ilmenite pairs, the magnetite

  20. Infrared study of the selective oxidation of toluene and o-xylene on vanadium oxide/TiO2

    NARCIS (Netherlands)

    van Hengstum, A.J.; Pranger, J.; Hengstum-Nijhuis, S.M.; van Ommen, J.G.; Gellings, P.J.

    1986-01-01

    Infrared spectroscopy was used to obtain information on the mechanism of the selective oxidation of toluene and o-xylene over vanadium oxide catalysts. The interaction of these aromatic hydrocarbons and the products benzaldehyde and o-tolualdehyde with the surface of a V2O5/TiO2 monolayer catalyst

  1. Structural, optical and electrochemical properties of F-doped vanadium oxide transparent semiconducting thin films

    Science.gov (United States)

    Mousavi, M.; Khorrami, Gh. H.; Kompany, A.; Yazdi, Sh. Tabatabai

    2017-12-01

    In this study, F-doped vanadium oxide thin films with doping levels up to 60 at % were prepared by spray pyrolysis method on glass substrates. To measure the electrochemical properties, some films were deposited on fluorine-tin oxide coated glass substrates. The effect of F-doping on the structural, electrical, optical and electrochemical properties of vanadium oxide samples was investigated. The X-ray diffractographs analysis has shown that all the samples grow in tetragonal β-V2O5 phase structure with the preferred orientation of [200]. The intensity of (200) peak belonging to β-V2O5 phase was strongest in the undoped vanadium oxide film. The scanning electron microscopy images show that the samples have nanorod- and nanobelt-shaped structure. The size of the nanobelts in the F-doped vanadium oxide films is smaller than that in the pure sample and the width of the nanobelts increases from 30 to 70 nm with F concentration. With increasing F-doping level from 10 to 60 at %, the resistivity, the transparency and the optical band gap decrease from 111 to 20 Ω cm, 70 to 50% and 2.4 to 2.36 eV, respectively. The cyclic voltammogram (CV) results show that the undoped sample has the most extensive CV and by increasing F-doping level from 20 to 60 at %, the area of the CV is expanded. The anodic and cathodic peaks in F-doped samples are stronger.

  2. Bipolar resistive switching in room temperature grown disordered vanadium oxide thin-film devices

    Science.gov (United States)

    Wong, Franklin J.; Sriram, Tirunelveli S.; Smith, Brian R.; Ramanathan, Shriram

    2013-09-01

    We demonstrate bipolar switching with high OFF/ON resistance ratios (>104) in Pt/vanadium oxide/Cu structures deposited entirely at room temperature. The SET (RESET) process occurs when negative (positive) bias is applied to the top Cu electrode. The vanadium oxide (VOx) films are amorphous and close to the vanadium pentoxide stoichiometry. We also investigated Cu/VOx/W structures, reversing the position of the Cu electrode, and found the same polarity dependence with respect to the top and bottom electrodes, which suggests that the bipolar nature is linked to the VOx layer itself. Bipolar switching can be observed at 100 °C, indicating that it not due to a temperature-induced metal-insulator transition of a vanadium dioxide second phase. We discuss how ionic drift can lead to the bipolar electrical behavior of our junctions, similar to those observed in devices based on several other defective oxides. Such low-temperature processed oxide switches could be of relevance to back-end or package integration processing schemes.

  3. Investigation of the interaction of benzene with vanadium-molybdenum oxide catalysts by programmed thermal desorption

    Energy Technology Data Exchange (ETDEWEB)

    Belokopytov, Yu.V.; Pyatnitskii, Yu.I.; Grebennikov, Yu.N.

    1985-09-01

    Programmed thermal desorption was used to investigate the interaction of benzene with vanadium-molybdenum oxide catalysts. It was established that the amount of maleic anhydride desorbed from the catalyst surface depends on the catalyst composition and that it varies with its activity and selectivity.

  4. A comprehensive model for the supported vanadium oxide catalyst: The umbrella model

    NARCIS (Netherlands)

    Lingen, J.N.J. van

    2006-01-01

    Supported vanadium oxide catalysts are widely used in industry. However, the molecular structure of the active species, responsible for the actual catalysis, is for a large part still unknown. This thesis describes four years study on the elucidation of this molecular structure. It mainly focuses on

  5. Raman and XPS characterization of vanadium oxide thin films with temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ureña-Begara, Ferran, E-mail: ferran.urena@uclouvain.be [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium); Crunteanu, Aurelian [XLIM Research Institute, UMR 7252, CNRS/Université de Limoges, Limoges (France); Raskin, Jean-Pierre [Université catholique de Louvain, Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Louvain-la-Neuve (Belgium)

    2017-05-01

    Highlights: • Comprehensive study of the oxidation of VO{sub 2} thin films from R.T. up to 550 °C. • Phase changes and mixed-valence vanadium oxides formed during the oxidation process. • Reported Raman and XPS signatures for each vanadium oxide. • Monitoring of the current and resistance evolution at the surface of the films. • Oxidation model describing the evolution of the vanadium oxides and phase changes. - Abstract: The oxidation mechanisms and the numerous phase transitions undergone by VO{sub 2} thin films deposited on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates when heated from room temperature (R.T.) up to 550 °C in air are investigated by Raman and X-ray photoelectron spectroscopy. The results show that the films undergo several intermediate phase transitions between the initial VO{sub 2} monoclinic phase at R.T. and the final V{sub 2}O{sub 5} phase at 550 °C. The information about these intermediate phase transitions is scarce and their identification is important since they are often found during the synthesis of vanadium dioxide films. Significant changes in the film conductivity have also been observed to occur associated to the phase transitions. In this work, current and resistance measurements performed on the surface of the films are implemented in parallel with the Raman measurements to correlate the different phases with the conductivity of the films. A model to explain the oxidation mechanisms and phenomena occurring during the oxidation of the films is proposed. Peak frequencies, full-width half-maxima, binding energies and oxidation states from the Raman and X-ray photoelectron spectroscopy experiments are reported and analyzed for all the phases encountered in VO{sub 2} films prepared on SiO{sub 2}/Si and Al{sub 2}O{sub 3} substrates.

  6. Importance of Vanadium-Catalyzed Oxidation of SO2to SO3in Two-Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Colom, Juan M.; Alzueta, María U.; Christensen, Jakob Munkholt

    2016-01-01

    Low-speed marine diesel engines are mostly operated on heavy fuel oils, which have a high content of sulfur andash, including trace amounts of vanadium, nickel, and aluminum. In particular, vanadium oxides could catalyze in-cylinderoxidation of SO2 to SO3, promoting the formation of sulfuric acid...... and enhancing problems of corrosion. In the present work, thekinetics of the catalyzed oxidation was studied in a fixed-bed reactor at atmospheric pressure. Vanadium oxide nanoparticles weresynthesized by spray flame pyrolysis, i.e., by a mechanism similar to the mechanism leading to the formation...

  7. Electrical and Infrared Optical Properties of Vanadium Oxide Semiconducting Thin-Film Thermometers

    Science.gov (United States)

    Zia, Muhammad Fakhar; Abdel-Rahman, Mohamed; Alduraibi, Mohammad; Ilahi, Bouraoui; Awad, Ehab; Majzoub, Sohaib

    2017-10-01

    A synthesis method has been developed for preparation of vanadium oxide thermometer thin film for microbolometer application. The structure presented is a 95-nm thin film prepared by sputter-depositing nine alternating multilayer thin films of vanadium pentoxide (V2O5) with thickness of 15 nm and vanadium with thickness of 5 nm followed by postdeposition annealing at 300°C in nitrogen (N2) and oxygen (O2) atmospheres. The resulting vanadium oxide (V x O y ) thermometer thin films exhibited temperature coefficient of resistance (TCR) of -3.55%/°C with room-temperature resistivity of 2.68 Ω cm for structures annealed in N2 atmosphere, and TCR of -3.06%/°C with room-temperature resistivity of 0.84 Ω cm for structures annealed in O2 atmosphere. Furthermore, optical measurements of N2- and O2-annealed samples were performed by Fourier-transform infrared ellipsometry to determine their dispersion curves, refractive index ( n), and extinction coefficient ( k) at wavelength from 7000 nm to 14,000 nm. The results indicate the possibility of applying the developed materials in thermometers for microbolometers.

  8. X-Ray Absorption Studies of Vanadium-Containing Metal Oxide Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hohn, Keith, L.

    2006-01-09

    Metal oxide nanocrystals offer significant potential for use as catalysts or catalyst supports due to their high surface areas and unique chemical properties that result from the high number of exposed corners and edges. However, little is known about the catalytic activity of these materials, especially as oxidation catalysts. This research focused on the preparation, characterization and use of vanadium-containing nanocrystals as selective oxidation catalysts. Three vanadium-containing nanocrystals were prepared using a modified sol-gel procedure: V/MgO, V/SiO2, and vanadium phosphate (VPO). These represent active oxidation catalysts for a number of industrially relevant reactions. The catalysts were characterized by x-ray diffraction and Raman, UV-VIS, infrared and x-ray absorption spectroscopies with the goal of determining the primary structural and chemical differences between nanocrystals and microcrystals. The catalytic activity of these catalysts was also studied in oxidative dehydrogenation of butane and methanol oxidation to formaldehyde. V/MgO nanocrystals were investigated for activity in oxidative dehydrogenation of butane and compared to conventional V/MgO catalysts. Characterization of V/MgO catalysts using Raman spectroscopy and x-ray absorption spectroscopy showed that both types of catalysts contained magnesium orthovanadate at vanadium loadings below 15 weight%, but above that loading, magnesium pyrovanadate may have been present. In general, MgO nanocrystals had roughly half the crystal size and double the surface area of the conventional MgO. In oxidative dehydrogenation of butane, nanocrystalline V/MgO gave higher selectivity to butene than conventional V/MgO at the same conversion. This difference was attributed to differences in vanadium domain size resulting from the higher surface areas of the nanocrystalline support, since characterization suggested that similar vanadium phases were present on both types of catalysts. Experiments in

  9. Importance of Vanadium-Catalyzed Oxidation of SO2to SO3in Two-Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Colom, Juan M.; Alzueta, María U.; Christensen, Jakob Munkholt

    2016-01-01

    Low-speed marine diesel engines are mostly operated on heavy fuel oils, which have a high content of sulfur andash, including trace amounts of vanadium, nickel, and aluminum. In particular, vanadium oxides could catalyze in-cylinderoxidation of SO2 to SO3, promoting the formation of sulfuric acid...... and enhancing problems of corrosion. In the present work, thekinetics of the catalyzed oxidation was studied in a fixed-bed reactor at atmospheric pressure. Vanadium oxide nanoparticles weresynthesized by spray flame pyrolysis, i.e., by a mechanism similar to the mechanism leading to the formation...... of the catalyticspecies within the engine. Experiments with different particle compositions (vanadium/sodium ratio) and temperatures (300−800 °C) show that both the temperature and sodium content have a major impact on the oxidation rate. Kinetic parameters forthe catalyzed reaction are determined, and the proposed...

  10. Diagnosis of deactivation sources for vanadium catalysts used in SO 2 oxidation reaction and optimization of vanadium extraction from deactivated catalysts

    Science.gov (United States)

    Ksibi, Mohamed; Elaloui, Elimam; Houas, Ammar; Moussa, Noomen

    2003-12-01

    Physico-chemical analysis (X-ray, FTIR) and/or methanol oxidation reaction test were performed on fresh and deactivated vanadium catalysts used in H 2SO 4 manufacturing. It allowed the diagnosis of catalyst deactivation sources, as well as the processes of regenerating and recycling the worn out catalyst in converter. One of these processes is hydrometallurgical method. It consists in treating the deactivated catalyst with alkaline or acidic reagents and forming vanadate solution. A simple and non-costly operation of chemical attack permits the extraction of vanadium from silica in deactivated catalyst. The extracted vanadium can be used for the confection of regenerated catalysts or metallic tools. After optimization, this method can be used for industrial application.

  11. Diagnosis of deactivation sources for vanadium catalysts used in SO{sub 2} oxidation reaction and optimization of vanadium extraction from deactivated catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ksibi, Mohamed; Elaloui, Elimam; Houas, Ammar; Moussa, Noomen

    2003-12-30

    Physico-chemical analysis (X-ray, FTIR) and/or methanol oxidation reaction test were performed on fresh and deactivated vanadium catalysts used in H{sub 2}SO{sub 4} manufacturing. It allowed the diagnosis of catalyst deactivation sources, as well as the processes of regenerating and recycling the worn out catalyst in converter. One of these processes is hydrometallurgical method. It consists in treating the deactivated catalyst with alkaline or acidic reagents and forming vanadate solution. A simple and non-costly operation of chemical attack permits the extraction of vanadium from silica in deactivated catalyst. The extracted vanadium can be used for the confection of regenerated catalysts or metallic tools. After optimization, this method can be used for industrial application.

  12. Multisensor system for determination of polyoxometalates containing vanadium at its different oxidation states.

    Science.gov (United States)

    Rudnitskaya, Alisa; Evtuguin, Dmitry V; Gamelas, Jose A F; Legin, Andrey

    2007-04-30

    The electronic tongue (ET) multisensor system has been employed for the detection of metal-oxygen cluster anions (polyoxometalates) containing vanadium (IV/V) atoms. Sensitivity of a variety of potentiometric chemical sensors with plasticized polyvinyl chloride and chalcogenide glass membranes was evaluated with respect to vanadyl/vanadate ions, decavanadate and a series of Keggin-type polyoxometalates (POM) such as alpha-[SiW(11)V(IV)O(40)](6-), alpha-[SiW(11)V(V)O(40)](5-), alpha-[BW(11)V(IV)O(40)](7-), alpha-[BW(11)V(V)O(40)](6-), alpha-[PW(11)V(IV)O(40)](5-) and alpha-[PW(12-n)V(n)(V)O(40)]((3+n)-) (n=1, 2, 3). Sensor's responses to vanadium complexes were evaluated in the pH range of 2.4-6.5 and a set of sensors appropriate for detecting a variety of vanadium species was selected. Such sensor array was able to distinguish different vanadium complexes allowing their simultaneous quantification in binary (V(IV)/V(V)) mixtures. The vanillyl alcohol oxidation with alpha-[SiW(11)V(V)O(40)](5-) was monitored using ET to evaluate the capacity of proposed analytic system to detect simultaneously V(IV)/V(V) in POM under dynamic equilibrium. ET was demonstrated to be a promising tool for the discrimination and quantification of vanadium-containing POMs at different oxidation states. In particular, such a system could represent a significant interest for the mechanistic studies of redox reactions with POMs.

  13. A new hybrid electrochromic material: vanadium oxide/ eriochrome black T

    Science.gov (United States)

    Junior, L. F. R.; de Oliveira, R. S.; Ponzio, E. A.

    2015-03-01

    In this work, we describe the synthesis of a new hybrid material, which is consists of the eriochrome black T (sodium 1-[(1-hydroxynaphthcalen-2-yl-hydrazinylidene]-6-nitro-2- naphthol-4-sulfonate) and vanadium pentoxide xerogel using a melting sonoquenching technique. This hybrid material was apply in electrochromic electrodes. The hybrid material was characterized by X-ray difraction, FT-IR, AFM and spectroelectrochemically. The hybrid presented good reversibility and cyclability during 50 cycles studied, electrochromic efficiencies were about 50 cm2 C-1 (375 nm and 400 nm) and the ΔOD at 375 nm and 400 nm were 0.236 and 0.159 respectively wavelenghts. The response times were 0.7 to 3.3 s for 375 nm and 0.7 to 2.0 s for 400 nm. The hybrid is a potential material to be used in electrochromic applications.

  14. Structure-property relationships in NOx sensor materials composed of arrays of vanadium oxide nanoclusters

    Science.gov (United States)

    Putrevu, Naga Ravikanth; Darling, Seth B.; Segre, Carlo U.; Ganegoda, Hasitha; Khan, M. Ishaque

    2017-12-01

    The mixed-valent vanadium oxide based three-dimensional framework structure species [Cd3(H2O)12V16IVV2VO36(OH)6 (AO4)]·24H2O, (A = V,S) (Cd3(VO)o) represents a rare example of an interesting sensor material which exhibits NOx {NO + NO2} semiconducting gas sensor properties under ambient conditions. The electrical resistance of the sensor material Cd3(VO)o decreases in air. Combined characterization studies revealed that the building block, {V18O42(AO4)} cluster, of 3-D framework undergoes oxidation and remains intact for at least 2 months. The decrease in resistance is attributable to the reactivity of molecular oxygen towards vanadium which results in an increase in the oxidation state as well as the coordination number of vanadium center and decrease in band gap of Cd3(VO)o. Based on these results we propose that the changes in semiconducting properties of Cd3(VO)o under ambient conditions are due to the greater overlap between the O 2p and V 3d orbitals occurring during the oxidation.

  15. Sol-gel synthesis and XPS study of vanadium-hydroquinone oxide bronze films

    Energy Technology Data Exchange (ETDEWEB)

    Bondarenka, V. [Semiconductor Physics Institute, A. Gostauto 11, 01108 Vilnius (Lithuania); Vilnius Pedagogical University, Studentu 39, 08106 Vilnius (Lithuania); Tvardauskas, H.; Grebinskij, S.; Senulis, M.; Pasiskevicius, A. [Semiconductor Physics Institute, A. Gostauto 11, 01108 Vilnius (Lithuania); Volkov, V.; Zakharova, G. [Institute of Solid State Chemistry, Pervomaiskaia 91, 620219 Yekaterinburg (Russian Federation)

    2009-12-15

    A vanadium - hydroquinone oxide bronze has been synthesized by using a sol gel technology. The V{sub 2}O{sub 5} powder, hydrogen peroxide, and hydroquinone C{sub 6}H{sub 4}(OH){sub 2} were used as the starting materials to produce the bronze. At first the vanadium gel was made by the dissolving of vanadium pentoxide powder in hydrogen peroxide at 273 K. Then the solution was heated up to 350 K for the dissociation of peroxide complexes. An aqueous solution of hydroquinone was mixed with the formed gel in molar ratio 0.33:1. In this way the V{sub 2}O{sub 5{+-}}{sub {delta}}.nH{sub 2}O/HQ (HQ-hydroquinone) gel was synthesized. These gels are applied on the Ni pad and dried in an air (wet gel synthesis) or heated up to 580 K in air for 1 h for the water removal from gel (bronze production). The wet gel, as well as a bronze, was investigated by means of XPS method. Analysis of V-O region of XPS spectra shows that vanadium in both cases (wet gel and bronze) is in stable V{sup 5+} state. Oxygen in wet gel can be associated with V ions, hydroxide group and water. In bronze oxygen is connected with V and hydrogen (hydroxide). (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Lattice Breathing Inhibited Layered Vanadium Oxide Ultrathin Nanobelts for Enhanced Sodium Storage.

    Science.gov (United States)

    Wei, Qiulong; Jiang, Zhouyang; Tan, Shuangshuang; Li, Qidong; Huang, Lei; Yan, Mengyu; Zhou, Liang; An, Qinyou; Mai, Liqiang

    2015-08-26

    Operating as the "rocking-chair" battery, sodium ion battery (SIB) with acceptable high capacity is a very promising energy storage technology. Layered vanadium oxide xerogel exhibits high sodium storage capacity. But it undergoes large lattice breathing during sodiation/desodiation, resulting in fast capacity fading. Herein, we develop a facile hydrothermal method to synthesize iron preintercalated vanadium oxide ultrathin nanobelts (Fe-VOx) with constricted interlayer spacing. Using the Fe-VOx as cathode for SIB, the lattice breathing during sodiation/desodiation is largely inhibited and the interlayer spacing is stabilized for reversible and rapid Na(+) insertion/extraction, displaying enhanced cycling and rate performance. This work presents a new strategy to reduce the lattice breathing of layered materials for enhanced sodium storage through interlayer spacing engineering.

  17. Morphology-dependent vanadium oxide nanostructures grown on Ti foil for Li-ion battery.

    Science.gov (United States)

    Wei, Lunzhen; Wang, Yuhang; Wang, Yanli; Xu, Ming; Zheng, Gengfeng

    2014-10-15

    Vanadium oxide is considered as a potential cathode material for lithium-ion batteries, while its performance is significantly restricted by its poor Li(+) ion diffusion rate and low electric conductivity. These ion and charge transport rates, however, are also well correlated with the 3-dimensional (3D) morphologies/structures of the electroactive materials. Herein, we synthesized three different nanostructured vanadium oxides on Ti foils. The comparison of electrochemical properties of these materials shows that the structures of electrodes have great influences on their performances. Among these structures, the nanoribbons are most beneficial for fast charge transfer and reduced contact resistance. In addition, the spaces between each nanoribbon provide efficient ion transport pathways and sufficient electrolyte penetration. The initial discharge and charge capacities of vanadium oxide nanoribbon reach to 322 and 310mAhg(-)(1), with a reversible discharge/charge capacity of 200mAhg(-)(1) at the current rate of 1C (1C=300mAg(-)(1)). Copyright © 2014 Elsevier Inc. All rights reserved.

  18. In situ laser Raman spectroscopy during sequential oxidizing and reducing conditions for a vanadium-phosphorous-oxide catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Soejarto, A. D.; Schrader, G. L. [Iowa State Univ. of Science and Technology, Ames, IA (United States). Dept. of Chemical Engineering; Coulston, G. W. [Dupont Central Research and Development, Wilmington, DE (United States)

    1996-10-01

    A vanadium-phosphorous-oxide (VPO) catalyst was studied by in situ laser Raman spectroscopy for n-butane oxidation to maleic anhydride. Raman characterization during steady-state flow revealed the presence of (VO){sub 2}P{sub 2}O{sub 7}. Sequential oxidizing and reducing conditions were explored at 350 degrees C and 400 degrees C. These unsteady-state operations showed that the formation of V(5+) phases was enhanced during oxidizing conditions, while Raman bands increased during reducing conditions, the latter due to the presence of (VO){sub 2}P{sub 2}O{sub 7}. 16 refs., 2 tabs. 6 figs.

  19. Effects of Vanadium Ions in Different Oxidation States on Myosin ATPase Extracted from the Solitary Ascidian, Halocynthia roretzi (Drasche) : Biochemistry

    OpenAIRE

    Hitoshi, Michibata; YUTAKA, ZENKO; Kenji, YAMADA; Masato, HASEGAWA; TATSURO, TERADA; TAKAHARU, NUMAKUANI; Biological Institute, Faculty of Science, University of Kanazawa; Department of Chemistry, Toyama College of Technology; Marine Biological Station,Tohoku University

    1989-01-01

    Some ascidians are known to accumulate vanadium ion within their tissues by 10^6-fold as that in sea water and store the metal ion in its reduced tetravalent and/or trivalent states. It is also well known that phosphoenzymes are inhibited by pentavalent vanadium ion over a range of 10nM to 1mM. In the present experiment we have therefore examined the effects of vanadium ions in different oxidation states on the activity of myosin ATPase extracted from the mantle of the ascidian, Halocynthia r...

  20. Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

    Energy Technology Data Exchange (ETDEWEB)

    Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C. [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Quimica; Ferreira, Glaucio B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Quimica; Mota, Claudio J.A., E-mail: cmota@iq.ufrj.br [INCT Energia e Ambiente, Universidade Federal do Rio de Janeiro, RJ (Brazil)

    2013-01-15

    The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

  1. A high-performance catalyst support for methanol oxidation with graphene and vanadium carbonitride.

    Science.gov (United States)

    Huang, Taizhong; Mao, Shun; Zhou, Guihua; Zhang, Zhaoliang; Wen, Zhenhai; Huang, Xingkang; Ci, Suqin; Chen, Junhong

    2015-01-28

    In this study, a graphene-vanadium carbonitride (G-V(C, N)) hybrid is reported as a novel support for the Pt catalyst in methanol oxidation. The catalytic activity of the Pt/G-V(C, N) hybrid for methanol oxidation is greatly enhanced compared with that of a commercial Pt/C catalyst with carbon black as the catalyst support. The outstanding catalytic activity of the Pt/G-V(C, N) catalyst suggests the potential of using graphene-metal carbonitride as the catalyst support in fuel cells.

  2. System Assessment of Carbon Dioxide Used as Gas Oxidant and Coolant in Vanadium-Extraction Converter

    Science.gov (United States)

    Du, Wei Tong; Wang, Yu; Liang, Xiao Ping

    2017-10-01

    With the aim of reducing carbon dioxide (CO2) emissions and of using waste resources in steel plants, the use of CO2 as a gas oxidant and coolant in the converter to increase productivity and energy efficiency was investigated in this study. Experiments were performed in combination with thermodynamic theory on vanadium-extraction with CO2 and oxygen (O2) mixed injections. The results indicate that the temperature of the hot metal bath decreased as the amount of CO2 introduced into O2 increased. At an injection of 85 vol.% O2 and 15 vol.% CO2, approximately 12% of additional carbon was retained in the hot metal. Moreover, the content of vanadium trioxide in the slag was higher. In addition, the O2 consumption per ton of hot metal was reduced by 8.5% and additional chemical energy was recovered by the controlled injection of CO2 into the converter. Therefore, using CO2 as a gas coolant was conducive to vanadium extraction, and O2 consumption was reduced.

  3. Oxydehydrogenation of Propane over Vanadium Oxide Supported on Kieselguhr or MCM-41

    Directory of Open Access Journals (Sweden)

    BY Jibril

    2012-06-01

    Full Text Available Supported vanadium oxide (5 wt% on either Kieselguhr or mesoporous MCM-41 was prepared using impregnation method and tested as a catalyst in propane oxidative dehydrogenation (POD. The catalyst samples were characterized using X-ray elemental analysis, Brunauer-Emmett-Teller (BET physisorption, and Z-ray Photoelectron Spectroscopy (XPS. After impregnation, the catalyst surface area decreased compared with that of the support. More drastic decrease was observed in the case of MCM-41 (77% than the Kieselguhr supported sample (48%. There are also different degrees of vanadium oxide-support interaction as reflected by the XPS result. Si-O binding energy of 531.5 eV was observed on MCM-41-supported sample compared with 529.5 eV for the Kieselguhr-supported sample. The catalyst tests were conducted at atmospheric pressure, with a propane to oxygen ratio of 0.7 - 3.6 and a reaction temperature of 400 - 700 °C. Oxidative dehydrogenation and combustion products were observed. Minor cracking reaction products (methane, ethane, and ethene were also produced above 550 °C. The highest propene yield of 14% was obtained from the Kieselguhr-supported sample at 700 °C and with a C3 H8 /O2  ratio of 1.5.

  4. Hysteresis Phenomena in Sulfur Dioxide Oxidation over Supported Vanadium Catalysts

    DEFF Research Database (Denmark)

    Masters, Stephen G.; Eriksen, Kim Michael; Fehrmann, Rasmus

    1997-01-01

    Catalyst deactivation and hysteresis behavior in industrial SO2-oxidation catalysts have been studied in the temperature region 350-480 C by combined in situ EPR spectroscopy and catalytic activity measurements. The feed gas composition simulated sulfuric acid synthesis gas and wet/dry de...

  5. Influence of phosphorus and potassium impurities on the properties of vanadium oxide supported on TiO2

    NARCIS (Netherlands)

    van Hengstum, A.J.; Pranger, J.; van Ommen, J.G.; Gellings, P.J.

    1984-01-01

    The catalytic properties of vanadium oxide catalysts supported on TiO2 from Tioxide were strongly affected by phosphorus and potassium, present as impurities in the TiO2 support. The effects observed were stronaly dependent on the type of hydrocarbon oxidised. In the oxidation of toluene to benzoic

  6. The oxidation of organic additives in the positive vanadium electrolyte and its effect on the performance of vanadium redox flow battery

    Science.gov (United States)

    Nguyen, Tam D.; Whitehead, Adam; Scherer, Günther G.; Wai, Nyunt; Oo, Moe O.; Bhattarai, Arjun; Chandra, Ghimire P.; Xu, Zhichuan J.

    2016-12-01

    Despite many desirable properties, the vanadium redox flow battery is limited, in the maximum operation temperature that can be continuously endured, before precipitation begins in the positive electrolyte. Many additives have been proposed to improve the thermal stability of the charged positive electrolyte. However, we have found that the apparent stability, revealed in laboratory testing, is often simply an artifact of the test method and arises from the oxidation of the additive, with corresponding partial reduction of V(V) to V(IV). This does not improve the stability of the electrolyte in an operating system. Here, we examined the oxidation of some typical organic additives with carboxyl, alcohol, and multi-functional groups, in sulfuric acid solutions containing V(V). The UV-vis measurements and titration results showed that many compounds reduced the state-of-charge (SOC) of vanadium electrolyte, for example, by 27.8, 88.5, and 81.9% with the addition of 1%wt of EDTA disodium salt, pyrogallol, and ascorbic acid, respectively. The cell cycling also indicated the effect of organic additives on the cell performance, with significant reduction in the usable charge capacity. In addition, a standard screening method for thermally stable additives was introduced, to quickly screen suitable additives for the positive vanadium electrolyte.

  7. Synthesis and characterization of alumina-supported vanadium oxide catalysts prepared by the molecular designed dispersion of VO(acac)2 complexes

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Baltes, M.; Voort, P. van der; Ramachandra Rao, R.; Catana, Gabriela; Schoonheydt, R.A.; Vansant, E.F.

    2000-01-01

    Alumina-supported vanadium oxide catalysts have been prepared by the molecular designed dispersion method, using the vanadyl acetylacetonate complex (VO(acac)2). The complex has been adsorbed on the support from solution, followed by thermal conversion into the corresponding supported vanadium oxide

  8. FT-IR Study of Adsorption and Oxidation of Toluene on Vanadium Oxide layered on ZrO_2

    OpenAIRE

    Ohno, Takashi; Hatayama, Fumikazu; Yoshida, Tsukasa; Miyata, Hisashi

    1994-01-01

    The adsorption and oxdation of toluene on mono- and multi-layer V-Zr oxides prepared by the gas-phase method and the surface structure of the catalysts under reaction conditions have been studied by Fourier-transform infrared spectroscopy as well as the microcatalytic method. From the adsorption of toluene on the V-Zr oxides, it is found that Lewis-acidic sites (vanadium ion) play an important role to form a π-complex of toluene. The methyl group of the π-complex is dehydrogenated by the V=O ...

  9. Oxidation of lactic acid by Vanadium(V) in sulphuric acid medium: a kinetic and mechanistic study

    OpenAIRE

    Clementin, Rosilene Maria; Takashima, Keiko

    1993-01-01

    The rate of lactic acid, HL, oxidation by vanadium(V), V(V), in sulphuric acid solution has been measured by monitoring, spectrophotometrically, the absorbance change of vanadium(IV), V(IV) in 760 nm at 30°C. This oxidation is a acid-catalysed, its dependence on acidity being complex. The rate constant or not the ionic strength. This reaction exhibited first order dependence on the V(V) and HL concentrations respectively and minimal dependence on sulphuric acid at lower concentrations (0.25 -...

  10. Development of Vanadium Phosphaate Catalysts for Methanol Production by Selective Oxidation of Methane.

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, R.L.

    1997-10-01

    This DOE sponsored study of methane partial oxidation was initiated at Amax Research and Development in Golden, CO in October of 1993. Shortly thereafter the management of Amax closed this R&D facility and the PI moved to the Colorado School of Mines. The project was begun again after contract transfer via a novation agreement. Experimental work began with testing of vandyl pyrophosphate (VPO), a well known alkane selective oxidation catalyst. It was found that VPO was not a selective catalyst for methane conversion yielding primarily CO. However, promotion of VPO with Fe, Cr, and other first row transition metals led to measurable yields for formaldehyde, as noted in the summary table. Catalyst characterization studies indicated that the role of promoters was to stabilize some of the vanadium in the V{sup 5+} oxidation state rather than the V{sup 4+} state formally expected for (VO){sub 2}P{sub 2}O{sub 7}.

  11. Ameliorative effect of vanadium on oxidative stress in stomach tissue of diabetic rats

    Science.gov (United States)

    Yilmaz-Ozden, Tugba; Kurt-Sirin, Ozlem; Tunali, Sevim; Akev, Nuriye; Can, Ayse; Yanardag, Refiye

    2014-01-01

    Between their broad spectrum of action, vanadium compounds are shown to have insulin mimetic/enhancing effects. Increasing evidence in experimental and clinical studies suggests that oxidative stress plays a major role in the pathogenesis of diabetes and on the onset of diabetic complications. Thus, preventive therapy can alleviate the possible side effects of the disease. The aim of the present study was to investigate the effect of vanadyl sulfate supplementation on the antioxidant system in the stomach tissue of diabetic rats. Male Swiss albino rats were randomly divided into 4 groups: control; control+vanadyl sulfate; diabetic; diabetic+vanadyl sulfate. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ; 65 mg/kg body weight). Vanadyl sulfate (100 mg/kg body weight) was given daily by gavage for 60 days. At the last day of the experiment, stomach tissues were taken and homogenized to make a 10% (w/v) homogenate. Catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST), myeloperoxidase (MPO), carbonic anhydrase (CA), glucose-6-phosphate dehydrogenase (G6PD) and lactate dehydrogenase (LDH) activities were determined in the stomach tissue. CAT, SOD, GR, GPx, GST, CA, G6PD and LDH activities were increased in diabetic rats when compared to normal rats. Vanadium treatment significantly reduced the elevated activities of GR, GPx, GST compared with the diabetic group whereas the decreases in CAT, SOD, CA, G6PD and LDH activities were insignificant. No significant change was seen for MPO activity between the groups. It was concluded that vanadium could be used for its ameliorative effect against oxidative stress in diabetes. PMID:24856383

  12. Preparation of silicon carbide-supported vanadium oxide and its application of removing NO by ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zi-Bo; Xu, Xu [Yangzhou University, College of Environmental Science and Engineering, Yangzhou, Jiangsu (China); Bai, Shu-Li [Wuyi University, College of Chemical and Environmental Engineering, Jiangmen, Guangdong (China); Guan, Yu-Jiang; Jiang, Sheng-Tao [Taizhou University, Environmental Engineering, Taizhou, Zhejiang (China)

    2017-03-15

    The aim of this work was to study the preparation of SiC-supported V{sub 2}O{sub 5} catalysts and the kinetics on selective catalytic reduction for NO with NH{sub 3} on the catalysts. Using incipient wetness impregnation methods, vanadium oxide was applied to silicon carbide to prepare a SiC-supported vanadium oxide. X-ray photoelectron spectroscopy analysis confirmed that V{sub 2}O{sub 5} existed in the prepared materials. Using the prepared materials as catalysts, selective catalytic reduction for NO by NH{sub 3} has been analyzed, and reaction kinetics on the catalysts was studied at 150-300 C. The obtained results showed that the reduction reaction on the catalysts is close to zero-order kinetics with respect to NH{sub 3}, first-order with respect to NO, and half-order to O{sub 2}. Apparent activation energy for the reduction reaction was found to be 38 kJ mol{sup -1}. The prepared materials are stable and reusable. (orig.)

  13. Vanadium and cadmium in vivo effects in teleost cardiac muscle: metal accumulation and oxidative stress markers.

    Science.gov (United States)

    Soares, S S; Martins, H; Gutiérrez-Merino, C; Aureliano, M

    2008-03-01

    Several biological studies associate vanadium and cadmium with the production of reactive oxygen species (ROS), leading to lipid peroxidation and antioxidant enzymes alterations. The present study aims to analyse and compare the oxidative stress responses induced by an acute intravenous exposure (1 and 7 days) to a sub-lethal concentration (5 mM) of two vanadium solutions, containing different vanadate n-oligomers (n=1-5 or n=10), and a cadmium solution on the cardiac muscle of the marine teleost Halobatrachus didactylus (Lusitanian toadfish). It was observed that vanadium is mainly accumulated in mitochondria (1.33+/-0.26 microM), primarily when this element was administrated as decameric vanadate, than when administrated as metavanadate (432+/-294 nM), while the highest content of cadmium was found in cytosol (365+/-231 nM). Indeed, decavanadate solution promotes stronger increases in mitochondrial antioxidant enzymes activities (catalase: +120%; superoxide dismutase: +140%) than metavanadate solution. On contrary, cadmium increases cytosolic catalase (+111%) and glutathione peroxidases (+50%) activities. It is also observed that vanadate oligomers induce in vitro prooxidant effects in toadfish heart, with stronger effects induced by metavanadate solution. In summary, vanadate and cadmium are differently accumulated in blood and cardiac subcellular fractions and induced different responses in enzymatic antioxidant defence mechanisms. In the present study, it is described for the first time the effects of equal doses of two different metals intravenously injected in the same fish species and upon the same exposure period allowing to understand the mechanisms of vanadate and cadmium toxicity in fish cardiac muscle.

  14. Structure, activity and kinetics of supported molybdenum oxide and mixed molybdenum-vanadium oxide catalysts prepared by flame spray pyrolysis for propane OHD

    DEFF Research Database (Denmark)

    Høj, Martin; Kessler, Thomas; Beato, Pablo

    2013-01-01

    . The catalytic experiments showed that the most selective molybdenum oxide catalysts for the ODH reaction were those with high Mo loadings of 7 to 15 wt% Mo, while the most selective mixed molybdenum-vanadium oxide catalyst were at 4 wt% Mo, where separate surface species of molybdenum and vanadium oxide were...... observed by Raman spectroscopy. A simple kinetic model based on the propane ODH reaction, parallel combustion of propane and sequential combustion of propene described the experimental results well and could be used to determine the optimal reaction conditions. © 2013 Elsevier B.V....

  15. Facile Synthesis of Vanadium Oxide/Reduced Graphene Oxide Composite Catalysts for Enhanced Hydroxylation of Benzene to Phenol

    Directory of Open Access Journals (Sweden)

    Yongli Dong

    2016-05-01

    Full Text Available The vanadium oxide/reduced graphene oxide (VOx/RGO composites have been prepared by a simple solvothermal method with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB. The microstructure and morphology of the resultant VOx/RGO composites have been well characterized. The VOx nanoparticles are highly dispersed on the RGO sheets with a particle size of about 25 nm. When used as hydroxylation catalysts, the VOx/RGO composites are more efficient than individual RGO and vanadium oxide catalysts. The enhanced catalytic performance may be related to not only the well dispersed VOx active species, but also the hydrophobic surface and huge π-electron system of RGO for the adsorption and activation of benzene. In addition, the effects of calcination conditions on the microstructure and catalytic properties of VOx/RGO composites have also been investigated. The uniform VOx nanoparticles on the separated RGO sheets show highly efficient catalytic performance, while the formation of aggregated HxV2O5 and bulk V2O5 species along with the destruction of RGO sheets are poor for the hydroxylation of benzene. Up to 17.4% yield of phenol is achieved under the optimized catalytic reaction conditions.

  16. Three-terminal field effect devices utilizing thin film vanadium oxide as the channel layer

    Science.gov (United States)

    Ruzmetov, Dmitry; Gopalakrishnan, Gokul; Ko, Changhyun; Narayanamurti, Venkatesh; Ramanathan, Shriram

    2010-06-01

    Electrostatic control of the metal-insulator transition (MIT) in an oxide semiconductor could potentially impact the emerging field of oxide electronics. Vanadium dioxide (VO2) is of particular interest due to the fact that the MIT happens in the vicinity of room temperature and it is considered to exhibit the Mott transition. We present a detailed account of our experimental investigation into three-terminal field effect transistor-like devices using thin film VO2 as the channel layer. The gate is separated from the channel through an insulating gate oxide layer, enabling true probing of the field effect with minimal or no interference from large leakage currents flowing directly from the electrode. The influence of the fabrication of multiple components of the device, including the gate oxide deposition, on the VO2 film characteristics is discussed. Further, we discuss the effect of the gate voltage on the device response, point out some of the unusual characteristics including temporal dependence. A reversible unipolar modulation of the channel resistance upon the gate voltage is demonstrated for the first time in optimally engineered devices. The results presented in this work are of relevance toward interpreting gate voltage response in such oxides as well as addressing challenges in advancing gate stack processing for oxide semiconductors.

  17. Graphene Oxide Wrapped Amorphous Copper Vanadium Oxide with Enhanced Capacitive Behavior for High-Rate and Long-Life Lithium-Ion Battery Anodes.

    Science.gov (United States)

    Zhao, Kangning; Liu, Fengning; Niu, Chaojiang; Xu, Wangwang; Dong, Yifan; Zhang, Lei; Xie, Shaomei; Yan, Mengyu; Wei, Qiulong; Zhao, Dongyuan; Mai, Liqiang

    2015-12-01

    Graphene oxide-wrapped amorphous copper vanadium oxide is fabricated through a template-engaged redox reaction followed by vacuum dehydration. This material exhibits high reversible capacity, excellent rate capability, and out standing high-rate cyclability. The outstanding performance is attributed to the fast capacitive charge storage and the in situ formed copper with enhanced electrical conductivity.

  18. Application of vanadium incorporated phosphomolybdate supported on the modified kaolinin synthesis of diphenyl carbonate by oxidative carbonylation with phenol

    Directory of Open Access Journals (Sweden)

    Peng Meng

    2017-01-01

    Full Text Available Keggin-type molybdophosphoric acid, molybdophosphoric salt and vanadium incorporated molybdophosphoric salt supported on the modified kaolin (MK were investigated as redox co-catalysts for the oxidative carbonylation of phenol to diphenyl carbonate (DPC in the absence of solvent. The 20 wt.% of MnAMPV5 (one kind of vanadium incorporated molybdophosphoric salt loaded on MK showed the highest catalytic activity with the yield of 24.68% and a TON of 306, while the selectivity amounts to nearly 100% in all the carbonylation reactions. The catalysts were characterized by XRD, BET, XPS and H2-TPR. The reusability study showed that the catalysts were stable and active.

  19. Vanadium carbide and graphite promoted Pd electrocatalyst for ethanol oxidation in alkaline media

    Science.gov (United States)

    Yan, Zaoxue; Zhang, Mingmei; Xie, Jimin; Shen, Pei Kang

    2013-12-01

    The vanadium carbide particles with the diameter of 1-3 nm on graphitized resin (GC-V8C7) are synthesized through ionic exchange process. The materials are characterized by XRD, Raman, TEM, SEM and EDS measurements. The results prove that the ion-exchange resin as both carbon source and dispersion media favors the formation of very uniform and small (1-3 nm) V8C7 particles, and protect the V8C7 from conglomeration even at the temperature of 1500 °C. Meanwhile, the vanadium compound is found efficient catalytic effect on graphitization of ion-exchange resin, leading to high graphitization degree of GC-V8C7. Pd particles are loaded on the GC-V8C7 materials as electrocatalyst (Pd/GC-V8C7) for ethanol oxidation in alkaline media. The cyclic voltammograms measurements show that both V8C7 and GC (graphitized ion-exchange resin) give Pd electrocatalyst improved catalytic performance in activity, stability and overpotential, compared with that of Pd supporting on Vulcan XC-72 carbon (Pd/C). The present synthesizing method of GC-V8C7 is simple and effective, which can be readily scaled up for mass production of other nanomaterials.

  20. Influence of doping on the properties of vanadium oxide gel films

    Energy Technology Data Exchange (ETDEWEB)

    Pergament, A L; Velichko, A A; Berezina, O Ya; Kazakova, E L; Kuldin, N A; Artyukhin, D V [Physics and Technology Department, Petrozavodsk State University, Petrozavodsk 185910 (Russian Federation)], E-mail: aperg@psu.karelia.ru

    2008-10-22

    The effect of doping with H and W on the properties of V{sub 2}O{sub 5} and VO{sub 2} derived from V{sub 2}O{sub 5} gel has been studied. It is shown that the treatment of V{sub 2}O{sub 5} in low-temperature RF hydrogen plasma for 1-10 min leads to either hydration of vanadium pentoxide or its reduction (depending on the treatment conditions) to lower vanadium oxides. For some samples, which are subject to plasma treatment in the discharge active zone, a non-ordinary temperature dependence of resistance, with a maximum at T{approx}100 K, is observed. For W-doped VO{sub 2} films, it is shown that substitution of V{sup 4+} with W{sup 6+} results in a decrease of the temperature of the metal-insulator transition. Also, it has been shown that the doping of initial films with {approx}3 at.% of W reduces the statistical scatter in the threshold parameters of the switching devices with S-shaped I-V characteristics on the basis of V{sub 2}O{sub 5} gel films. (fast track communication)

  1. Oxidation States of Grim Glasses in EET79001 Based on Vanadium Valence

    Science.gov (United States)

    Sutton, S. R.; Rao, M. N.; Nyquist, L. E.

    2010-01-01

    Gas-rich impact-melt (GRIM) glasses in SNC meteorites are very rich in Martian atmospheric noble gases and sulfur suggesting a possible occurrence of regolith-derived secondary mineral assemblages in these samples. Previously, we have studied two GRIM glasses, 506 and 507, from EET79001 Lith A and Lith B, respectively, for elemental abundances and spatial distribution of sulfur using EMPA (WDS) and FE-SEM (EDS) techniques and for sulfur-speciation using K-edge XANES techniques. These elemental and FE-SEM micro-graph data at several locations in the GRIM glasses from Shergotty (DBS), Zagami 994 and EET79001, Lith B showed that FeO and SO3 are positively correlated (SO3 represents a mixture of sulfide and sulfate). FE-SEM (EDS) study revealed that the sulfur-rich pockets in these glasses contain numerous micron-sized iron-sulfide (Fe-S) globules sequestered throughout the volume. However, in some areas (though less frequently), we detected significant Fe-S-O signals suggesting the occurrence of iron sulfate. These GRIM glasses were studied by K-edge microXANES techniques for sulfur speciation in association with iron in sulfur-rich areas. In both samples, we found the sulfur speciation dominated by sulfide with minor oxidized sulfur mixed in with various proportions. The abundance of oxidized sulfur was greater in 506 than in 507. Based on these results, we hypothesize that sulfur initially existed as sulfate in the glass precursor materials and, on shock-impact melting of the precursor materials producing these glasses, the oxidized sulfur was reduced to predominately sulfide. In order to further test this hypothesis, we have used microXANES to measure the valence states of vanadium in GRIM glasses from Lith A and Lith B to complement and compare with previous analogous measurements on Lith C (note: 506 and 507 contain the largest amounts of martian atmospheric gases but the gas-contents in Lith C measured by are unknown). Vanadium is ideal for addressing this re

  2. Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

    KAUST Repository

    Xia, Chuan

    2018-02-12

    Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

  3. Properties of electrochromic nickel-vanadium oxide films sputter-deposited from nonmagnetic alloy target

    Science.gov (United States)

    Avendano, Esteban; Azens, Andris; Niklasson, Gunnar A.

    2001-11-01

    In this study we investigate the structure, composition, diffusion coefficient, and electrochromic properties of nickel-vanadium oxide films as a function of deposition conditions. Polycrystalline films have been deposited by DC magnetron sputtering from a nonmagnetic target of Ni0.93V0.07 in an atmosphere of O2/Ar and Ar/O2/H2, with the gas flow ratios varied systematically to cover the range from nearly-metallic to overoxidized films. The results contradict the usual view that films deposited in O2/Ar are dark brown in their as-deposited state. While such films can easily be deposited, the optimum electrochromic properties have been observed at O2/Ar ratios giving nearly transparent films. Addition of hydrogen to the sputtering atmosphere improved cycling stability of the films. The diffusion coefficient has been determined by the Galvanostatic Intermittent Titration Technique (GITT).

  4. Induced dipole in vanadium-doped zinc oxide nanosheets and its effects on photoelectrochemical water splitting

    Science.gov (United States)

    Lee, Song Mi; Shin, Sung-Ho; Nah, Junghyo; Lee, Min Hyung

    2017-09-01

    Appropriate control of energy band bending at the interface between semiconductors and electrolytes are closely related to performance of photoelectrochemical (PEC) water splitting. Dipoles formed near the surface of semiconductors induces energy band bending at the interface. Energy band bending control has been demonstrated by employing charged molecules and piezoelectric materials. However, chemical and piezoelectric approaches have demerit of chemical instability and inducement of instantaneous dipole, respectively. To overcome these problems, we adopted the ferroelectric material for PEC water splitting, where spontaneous dipoles in the material can be oriented by applying external electric field. In this work, we hydrothermally synthesized vanadium (V)-doped ferroelectric ZnO nanosheets and employed to systematically investigate the dipole effect on performance of V-doped ZnO PEC for water oxidation. Consequently, positively polarized V-doped ZnO photoanode exhibits 125% enhanced water splitting efficiency compared to negatively polarized ones due to favorable band bending for carrier transport from semiconductor to water.

  5. Switching adhesion forces by crossing the metal–insulator transition in Magnéli-type vanadium oxide crystals

    Directory of Open Access Journals (Sweden)

    Bert Stegemann

    2011-01-01

    Full Text Available Magnéli-type vanadium oxides form the homologous series VnO2n-1 and exhibit a temperature-induced, reversible metal–insulator first order phase transition (MIT. We studied the change of the adhesion force across the transition temperature between the cleavage planes of various vanadium oxide Magnéli phases (n = 3 … 7 and spherical titanium atomic force microscope (AFM tips by systematic force–distance measurements with a variable-temperature AFM under ultrahigh vacuum conditions (UHV. The results show, for all investigated samples, that crossing the transition temperatures leads to a distinct change of the adhesion force. Low adhesion corresponds consistently to the metallic state. Accordingly, the ability to modify the electronic structure of the vanadium Magnéli phases while maintaining composition, stoichiometry and crystallographic integrity, allows for relating frictional and electronic material properties at the nano scale. This behavior makes the vanadium Magnéli phases interesting candidates for technology, e.g., as intelligent devices or coatings where switching of adhesion or friction is desired.

  6. Vanadium sulfides interwoven nanoflowers based on in-situ sulfurization of vanadium oxides octahedron on nickel foam for efficient hydrogen evolution

    Science.gov (United States)

    Rao, Yi; Zhang, Li-Ming; Shang, Xiao; Dong, Bin; Liu, Yan-Ru; Lu, Shan-Shan; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

    2017-11-01

    Novel vanadium sulfides interwoven nanoflowers supported on nickel foam (VO-S/NF) has been synthesized through a facile two-step access. Firstly, octahedron-structured vanadium oxides as precursor were anchored on the surface of NF (VO/NF) by a hydrothermal process. Secondly, in-situ sulfurization in H2S gas has been applied to prepare VO-S/NF. XRD shows that VO-S/NF sample is composed of mixture phases including VS and Ni3S2, implying the interface effect between VS and Ni3S2. SEM images demonstrate that octahedron-structured VO from VO/NF changed to VO-S interwoven nanoflowers on VO-S/NF, which are composed of vertical interwoven nanosheets. It can enlarge surface area to expose abundant active sites and facilitate mass and charge transportation. The electrochemical measurements display the enhanced HER activity of VO-S/NF requiring an overpotential of 165 mV to deliver 10 mA cm-2, which may be ascribed to the novel structure of VS interwoven nanosheets and the synergistic effect between VS and Ni3S2. Furthermore, VO-S/NF remains high HER activity for at least 10 h with excellent structural stability confirmed by post-HER characterization such as XRD, SEM and XPS. Therefore, it may provide a new way to design multiple transition metal sulfides-based electrocatalysts with unique nanostructure as well as interface effect for HER in alkaline.

  7. Visible light photooxidative performance of a high-nuclearity molecular bismuth vanadium oxide cluster

    Directory of Open Access Journals (Sweden)

    Johannes Tucher

    2014-05-01

    Full Text Available The visible light photooxidative performance of a new high-nuclearity molecular bismuth vanadium oxide cluster, H3[{Bi(dmso3}4V13O40], is reported. Photocatalytic activity studies show faster reaction kinetics under anaerobic conditions, suggesting an oxygen-dependent quenching of the photoexcited cluster species. Further mechanistic analysis shows that the reaction proceeds via the intermediate formation of hydroxyl radicals which act as oxidant. Trapping experiments using ethanol as a hydroxyl radical scavenger show significantly decreased photocatalytic substrate oxidation in the presence of EtOH. Photocatalytic performance analyses using monochromatic visible light irradiation show that the quantum efficiency Φ for indigo photooxidation is strongly dependent on the irradiation wavelength, with higher quantum efficiencies being observed at shorter wavelengths (Φ395nm ca. 15%. Recycling tests show that the compound can be employed as homogeneous photooxidation catalyst multiple times without loss of catalytic activity. High turnover numbers (TON ca. 1200 and turnover frequencies up to TOF ca. 3.44 min−1 are observed, illustrating the practical applicability of the cluster species.

  8. Hydration effects on the molecular structure of silica-supported vanadium oxide catalysts: A combined IR, Raman, UV–vis and EXAFS study

    OpenAIRE

    Keller, D.E.; Visser, T; Soulimani, F.; Koningsberger, D. C.; Weckhuysen, B.M.

    2007-01-01

    The effect of hydration on the molecular structure of silica-supported vanadium oxide catalysts with loadings of 1–16 wt.% V has been systematically investigated by infrared, Raman, UV–vis and EXAFS spectroscopy. IR and Raman spectra recorded during hydration revealed the formation of V–OH groups, characterized by a band at 3660 cm−1. Hydroxylation was found to start instantaneously upon exposure to traces of water, reflecting a very high sensitivity of the supported vanadium oxide catalysts ...

  9. Molecular manipulation of solid state structure: influences of organic components on vanadium oxide architectures

    Science.gov (United States)

    Hagrman, Pamela J.; Finn, Robert C.; Zubieta, Jon

    2001-11-01

    /organic composites. In the past decade, this general strategy has been exploited in the evolution of a family of vanadium oxides incorporating structure-directing organic or secondary-metal organic subunits, which are the topic of this review. The synthetic approach to novel vanadium oxide solids occupies the interface between materials science and coordination chemistry. The emerging theme focuses on the association of an organic component, acting as a ligand, tether, or structure directing moiety, with the inorganic framework of the solid to provide unique composites. While some organic components may limit the size of inorganic cluster subunits of a solid by passivating the surface of an aggregate through capping, such ligands may also serve to link inorganic subunits into complex networks. In other cases, the organic subunit, rather than participating as a covalently bound unit of the framework, acts in a structure directing role, producing amphiphilic materials whose structures are determined by hydrophobic-hydrophilic interactions. This latter feature is reminiscent of the factors influencing biomineralization, a field which may prove relevant to the development of new strategies for the controlled synthesis of organized inorganic and organic/inorganic composite materials. These various approaches to the "design" of inorganic solids are discussed and assessed in terms of the new structural types recently observed in the vanadium oxide chemistry.

  10. Three-dimensional Nitrogen-Doped Reduced Graphene Oxide/Carbon Nanotube Composite Catalysts for Vanadium Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Engelhard, Mark H. [Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.

    2017-02-22

    The development of vanadium redox flow battery is limited by the sluggish kinetics of the reaction, especially the cathodic VO2+/VO2+ redox couples. Therefore, it is vital to develop new electrocatalyst with enhanced activity to improve the battery performance. Herein, we first synthesized the hydrogel precursor by a facile hydrothermal method. After the following carbonization, nitrogen-doped reduced graphene oxide/carbon nanotube composite was obtained. By virtue of the large surface area and good conductivey, which are ensured by the unique hybrid structure, as well as the proper nitrogen doping, the as-prepared composite presents enhanced catalytic performance toward the VO2+/VO2+ redox reaction. We also demonstrated the composite with carbon nanotube loading of 2 mg/mL exhibits the highest activity and remarkable stability in aqueous solution due to the strong synergy between reduced graphene oxide and carbon nanotubes, indicating that this composite might show promising applications in vanadium redox flow battery.

  11. Amorphous Cobalt Vanadium Oxide as a Highly Active Electrocatalyst for Oxygen Evolution.

    Science.gov (United States)

    Liardet, Laurent; Hu, Xile

    2018-01-05

    The water-splitting reaction provides a promising mechanism to store renewable energies in the form of hydrogen fuel. The oxidation half-reaction, the oxygen evolution reaction (OER), is a complex four-electron process that constitutes an efficiency bottleneck in water splitting. Here we report a highly active OER catalyst, cobalt vanadium oxide. The catalyst is designed on the basis of a volcano plot of metal-OH bond strength and activity. The catalyst can be synthesized by a facile hydrothermal route. The most active pure-phase material ( a- CoVO x ) is X-ray amorphous and provides a 10 mA cm -2 current density at an overpotential of 347 mV in 1 M KOH electrolyte when immobilized on a flat substrate. The synthetic method can also be applied to coat a high-surface-area substrate such as nickel foam. On this three-dimensional substrate, the a- CoVO x catalyst is highly active, reaching 10 mA cm -2 at 254 mV overpotential, with a Tafel slope of only 35 mV dec -1 . This work demonstrates a- CoVO x as a promising electrocatalyst for oxygen evolution and validates M-OH bond strength as a practical descriptor in OER catalysis.

  12. Influence of Na diffusion on thermochromism of vanadium oxide films and suppression through mixed-alkali effect

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Mark J.; Wang, Junlan, E-mail: junlan@u.washington.edu

    2015-10-15

    Highlights: • Vanadium oxide films were reactively sputtered on three types of glass substrates. • Na diffusion from soda-lime glass undesirably inhibited thermochromism. • Na diffusion was suppressed by replacing half of sodium in glass with potassium. • Mixed-alkali effect promotes thermochromic VO{sub 2} films on glass substrates. - Abstract: Vanadium(IV) oxide possesses a reversible first-order phase transformation near 68 °C. Potential applications of the material include advanced optical devices and thermochromic smart windows. In this study, vanadium oxide films were grown on three types of glass substrates using reactive DC magnetron sputtering and were then annealed in air. The substrates were characterized with energy-dispersive X-ray spectroscopy, and the films were characterized with X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and UV-Vis-NIR spectrophotometry. The results show that the composition of the substrate has a major impact on the microstructure and optical properties of the deposited films. Sodium (Na) in the glass can undesirably inhibit thermochromism; however, replacing half of the Na with potassium (K) suppresses the Na diffusion and promotes the nucleation of pure VO{sub 2} with superior thermochromic functionality. The improved performance is attributed to the mixed-alkali effect between Na and K. These findings are both scientifically and technologically important since soda (Na{sub 2}O) is an essential flux material in glass products such as windows.

  13. Release of vanadium from oxidized sediments: insights from different extraction and leaching procedures.

    Science.gov (United States)

    Cappuyns, V; Swennen, R

    2014-02-01

    Although the attention for vanadium (V) as a potentially harmful element is growing and some countries adopted threshold values for V in soils, sediments, groundwater, or surface water, V is generally of little importance in environmental legislation and the knowledge about the behavior of V in the environment is still limited. In the present study, the release of V from oxidized sediments, sediment-derived soils, and certified reference materials was investigated by means of several types of leaching tests and extractions that are frequently used for soil and sediment characterization. The pHstat leaching tests and single and sequential extractions applied in this study show that V generally displays a very limited actual and potential mobility in sediment. "Mobile" V concentrations, as estimated by the amount of V released by a single extraction with CaCl2 0.01 mol L(-1), were low, even in the most contaminated sediment samples. Only under strongly acidifying conditions (pH 2), such as in the case of ingestion of soil or sediment or in accidental spills, a substantial release of V can be expected.

  14. The microstructures and electrical properties of Y-doped amorphous vanadium oxide thin films

    Science.gov (United States)

    Gu, Deen; Zhou, Xin; Guo, Rui; Wang, Zhihui; Jiang, Yadong

    2017-03-01

    One of promising approaches for further improving the sensitivity of microbolometer arrays with greatly-reduced pixel size is using the thermal-sensitive materials with higher performance. In this paper, Y-doped vanadium oxide (VOx) thin films prepared by a reactively sputtering process exhibit enhanced performance for the microbolometer application compared with frequently-applied VOx thin films. Both undoped and Y-doped VOx thin films are amorphous due to the relatively low deposition temperature. Y-doped VOx thin films exhibit smoother surface morphology than VOx due to the restrained expansion of particles during depositions. Y-doping increases the temperature coefficient of resistivity by over 20% for the doping level of 1.30 at%. The change rate of resistivity, after aging for 72 h, of thin films was reduced from about 15% for undoped VOx to 2% due to the introduction of Y. Moreover, Y-doped VOx thin films have a low 1/f noise level as VOx ones. Y-doping provides an attractive approach for preparing VOx thermal-sensitive materials with enhanced performance for microbolometers.

  15. The mechanism of cysteine detection in biological media by means of vanadium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, A. G. [Universidade Tecnologica Federal do Parana, Departamento Academico de Fisica (Brazil); Barison, A. [Universidade Federal do Parana, Departamento de Quimica (Brazil); Oliveira, V. S. [Universidade Federal do Parana, Departamento de Fisica (Brazil); Foti, L.; Krieger, M. A. [Fundacao Oswaldo Cruz, Instituto de Biologia Molecular do Parana (Brazil); Dhalia, R.; Viana, I. F. T. [Fundacao Oswaldo Cruz, Centro de Pesquisas Aggeu Magalhaes (Brazil); Schreiner, W. H., E-mail: wido@fisica.ufpr.br [Universidade Federal do Parana, Departamento de Fisica (Brazil)

    2012-09-15

    We report on the interaction of vanadate nanoparticles, produced using the laser ablation in liquids synthesis, with cysteine in biological molecules. Cysteine is a very important amino acid present in most proteins, but also because cysteine and the tripeptide glutathione are the main antioxidant molecules in our body system. Detailed UV-Vis absorption spectra and dynamic light scattering measurements were done to investigate the detection of cysteine in large biological molecules. The intervalence band of the optical absorption spectra shows capability for quantitative cysteine sensing in the {mu}M range in biological macromolecules. Tests included cytoplasmic repetitive antigen and flagellar repetitive antigen proteins of the Trypanosoma cruzi protozoa, as well as the capsid p24 proteins from Human Immunodeficiency Virus type 1 and type 2. Detailed NMR measurements for hydrogen, carbon, and vanadium nuclei show that cysteine in contact with the vanadate looses hydrogen of the sulphydryl side chain, while the vanadate is reduced. The subsequent detachment of two deprotonated molecules to form cystine and the slow return to the vanadate complete the oxidation-reduction cycle. Therefore, the vanadate acts as a charge exchanging catalyst on cysteine to form cystine. The NMR results also indicate that the nanoparticles are not formed by the common orthorhombic V{sub 2}O{sub 5} form.

  16. Properties of Vanadium-Doped Indium Oxide Deposited at Room Temperature as Transparent Conductor for Inverted Polymer Solar Cells

    Science.gov (United States)

    Choi, Min-Jun; Lim, Keun Yong; Park, Hyun-Woo; Kim, Han-Ki; Hwang, Do Kyung; Lim, Sung-Jin; Shim, Jae Won; Chung, Kwun-Bum

    2017-10-01

    The properties of vanadium-doped indium oxide (IVO) deposited at room temperature as a transparent conductor for inverted polymer solar cells have been investigated as a function of the vanadium doping concentration. IVO film prepared with V doping concentration of 0.03% showed optimal properties for use as a transparent conductor with figure of merit of 4.35 × 10-3 Ohm-1, related to altered band alignment between the Fermi level and conduction-band minimum. In the optimal optoelectrical conditions for the IVO film, performance optimization of PTB7:PC70BM inverted polymer solar cells resulted in maximum power conversion efficiency of 4.7 ± 0.4% under simulated air mass 1.5 global illumination at 100 mW/cm2.

  17. A high-resolution electron microscopy investigation of TiO sub 2 (B)-supported vanadium oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Wallenberg, L.R.; Sanati, M.; Andersson, A. (Lund Institute of Technology (Sweden))

    1990-11-01

    TiO{sub 2}(B) crystals were found to be isomorphic with those of its precursor, K{sub 2}TI{sub 4}O{sub 9}. The former crystals had a large number of facetted voids, 3-30 nm, formed as a result of the removal of potassium and water in preceding hydrolysis and calcination steps, respectively. TiO{sub 2}(B)-supported vanadium oxide catalysts with loadings in the range 0.25-10 theoretical layers were prepared by impregnation of the support with an oxalic acid solution of NH{sub 4}VO{sub 3} followed by calcination in air. HREM micrographs of catalysts with a low vanadium loading, recorded using a low electron-dose imaging technique, showed that the surfaces, in the initial stage, were without any anomalous surface structure. This observation may be due to a similar structure of the support and the deposited vanadia phase. At high vanadium loadings, both amorphous and crystalline particles were seen, in agreement with the features revealed by the use of IR spectroscopy. For catalysts with low vanadium loadings, the IR difference spectra showed the presence of tetrahedrally coordinated V{sup 4+} and V{sub 5+} species. In a fully converged electron beam, reduction of the support and the vanadia phases occurred, resulting in the formation of small crystallites. The catalysts were used for the oxidation of toluene to benzaldehyde. However, contrary to what has been observed for the ammoxidation producing benzonitrile, no enhanced catalytic properties, in comparison with those of crystalline V{sub 2}O{sub 5}, were obtained using TiO{sub 2}(B) as support.

  18. Investigation of Silica-Supported Vanadium Oxide Catalysts by High-Field 51 V Magic-Angle Spinning NMR

    Energy Technology Data Exchange (ETDEWEB)

    Jaegers, Nicholas R.; Wan, Chuan; Hu, Mary Y.; Vasiliu, Monica; Dixon, David A.; Walter, Eric; Wachs, Israel E.; Wang, Yong; Hu, Jian Zhi

    2017-03-14

    Supported V2O5/SiO2 catalysts were studied using solid state 51V MAS NMR at a sample spinning rate of 36 kHz and at a magnetic field of 19.975 T for a better understanding of the coordination of the vanadium oxide as a function of environmental conditions . Structural transformations of the supported vanadium oxide species between the catalyst in the dehydrated state and hydrated state under an ambient environment were revisited to examine the degree of oligomerization and the effect of water. The experimental results indicate the existence of a single dehydrated surface vanadium oxide species that resonates at -675 ppm and two vanadium oxide species under ambient conditions that resonate at -566 and -610 ppm, respectively. No detectable structural difference was found as a function of vanadium oxide loading on SiO2 (3% V2O5/SiO2 and 8% V2O5/SiO2). Quantum chemistry simulations of the 51V NMR chemical shifts on predicted surface structures were used as an aide in understanding potential surface vanadium oxide species on the silica support. The results suggest the formation of isolated surface VO4 units for the dehydrated catalysts with the possibility of dimer and cyclic trimer presence. The absence of bridging V-O-V vibrations (~200-300 cm-1) in the Raman spectra [Gao et al. J. Phys. Chem. B 1998, 102, 10842-10852], however, indicates that the isolated surface VO4 sites are the dominant dehydrated surface vanadia species on silica. Upon exposure to water, hydrolysis of the bridging V-O-Si bonds is most likely responsible for the decreased electron shielding experienced by vanadium. No indicators for the presence of hydrated decavanadate clusters or hydrated vanadia gels previously proposed in the literature were detected in this study.

  19. Amorphous and Crystalline Vanadium Oxides as High-Energy and High-Power Cathodes for Three-Dimensional Thin-Film Lithium Ion Batteries.

    Science.gov (United States)

    Mattelaer, Felix; Geryl, Kobe; Rampelberg, Geert; Dendooven, Jolien; Detavernier, Christophe

    2017-04-19

    Flexible wearable electronics and on-chip energy storage for wireless sensors drive rechargeable batteries toward thin-film lithium ion batteries. To enable more charge storage on a given surface, higher energy density materials are required, while faster energy storage and release can be obtained by going to thinner films. Vanadium oxides have been examined as cathodes in classical and thin-film lithium ion batteries for decades, but amorphous vanadium oxide thin films have been mostly discarded. Here, we investigate the use of atomic layer deposition, which enables electrode deposition on complex three-dimensional (3D) battery architectures, to obtain both amorphous and crystalline VO2 and V2O5, and we evaluate their thin-film cathode performance. Very high volumetric capacities are found, alongside excellent kinetics and good cycling stability. Better kinetics and higher volumetric capacities were observed for the amorphous vanadium oxides compared to their crystalline counterparts. The conformal deposition of these vanadium oxides on silicon micropillar structures is demonstrated. This study shows the promising potential of these atomic layer deposited vanadium oxides as cathodes for 3D all-solid-state thin-film lithium ion batteries.

  20. Partial oxidation of n- and i-pentane over promoted vanadium-phosphorus oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zazhigalov, V.A.; Mikhajluk, B.D.; Komashko, G.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    It is known, that the cost of raw materials for catalytic oxidation processes is about 60% of the product price. Cheap initial compounds to produce variety of products and to replace olefins and aromatic hydrocarbons are paraffins. That is why catalytic systems which could be possibly rather efficient in selective oxidation of paraffin hydrocarbons are under very close investigation now. One of such processes in n-pentane oxidation. The obtained results on n-pentane oxidation over VPO catalysts were quite encouraging in respect of possible reach high selectivity and yield of phthalic anhydride. However, in our work it was shown that the main product of n-pentane oxidation in the presence of VPO catalytic system as well as VPMeO was maleic anhydride. Some later our results were confirmed in, where to grow the selectivity towards phthalic anhydride the Co-additive was introduced. On the basis of the proposal made before on the mechanism of paraffins conversion over the vanadyl pyrophosphate surface with their activation at the first and fourth carbon atoms, we assumed possible methylmaleic (citraconic) anhydride forming at n- and i-pentane oxidation. This assumption has been recently supported by both our and other researchers` experimental results. In it was also hypothized possible mechanistic features for phthalic anhydride forming from n-pentane. The present work deals with the results of n- and i-pentane oxidation over VPO catalysts promoted with Bi, Cs, Te, Zr. (orig.)

  1. Incorporation of Vanadium Oxide in Silica Nanofiber Mats via Electrospinning and Sol-Gel Synthesis

    Directory of Open Access Journals (Sweden)

    Jeanne E. Panels

    2006-01-01

    Full Text Available Submicron scale vanadia/silica hybrid nanofiber mats have been produced by electrospinning silica sol-gel precursor containing vanadium oxytriisopropoxide (VOTIP, followed by calcinations at high temperature. The properties of the resulting inorganic hybrid nanofiber mats are compared to those of electrospun pure silica nanofibers. SEM images show fibers are submicron in diameter and their morphology is maintained after calcination. Physisorption experiments reveal that silica nanofiber mats have a high specific surface area of 63 m2/g. FT-IR spectra exhibit Si—O vibrations and indicate the presence of V2O5 in the fibers. XPS studies reveal that the ratio of Si to O is close to 0.5 on the surface of fibers and the amount of vanadium on the surface of fibers increases with calcination. XRD diffraction patterns show that silica nanofibers are amorphous and orthorhombic V2O5 crystals have formed after calcination. EFTEM images demonstrate the growth of crystals on the surface of fibers containing vanadium after calcination. SEM images of fibers with high-vanadium content (50 mol% V: Si show that vanadia crystals are mostly aligned along the fiber axis. XPS shows an increase in vanadium contents at the surface, and XRD patterns exhibit an increase in the degree of crystallinity. A coaxial electrospinning scheme has successfully been employed to selectively place V2O5 in the skin layer.

  2. Silver Vanadium Phosphorous Oxide, Ag(2)VO(2)PO(4): Chimie Douce Preparation and Resulting Lithium Cell Electrochemistry.

    Science.gov (United States)

    Kim, Young Jin; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2011-08-15

    Recently, we have shown silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4), SVPO) to be a promising cathode material for lithium based batteries. Whereas the first reported preparation of SVPO employed an elevated pressure, hydrothermal approach, we report herein a novel ambient pressure synthesis method to prepare SVPO, where our chimie douce preparation is readily scalable and provides material with a smaller, more consistent particle size and higher surface area relative to SVPO prepared via the hydrothermal method. Lithium electrochemical cells utilizing SVPO cathodes made by our new process show improved power capability under constant current and pulse conditions over cells containing cathode from SVPO prepared via the hydrothermal method.

  3. Thermo-electrical properties of composite semiconductor thin films composed of nanocrystalline graphene-vanadium oxides.

    Science.gov (United States)

    Jung, Hye-Mi; Um, Sukkee

    2014-12-01

    This paper presents an experimental comparative study involving the characterization of the thermo-electrical and structural properties of graphene-based vanadium oxide (graphene-VOx) composite thin films on insulating and conducting surfaces (i.e., fused quartz and acrylic resin-impregnated graphite) produced by a sol-gel process via dipping-pyrolysis. A combination of FE-SEM and XPS analyses revealed that the graphene-VOx composite thin films (coated onto fused quartz) exhibiting the microstructure of 2-graded nanowire arrays with a diameter of 40-80 nm were composed of graphene, a few residual oxygen-containing functional groups (i.e., C-O and C=O), and the VO2 Magnéli phase. The temperature-dependent electrical resistance measured on the as-deposited thin films clearly demonstrated that the graphene-VOx composite nanowire arrays thermally grown on fused quartz act as a semiconductor switch, with a transition temperature of 64.7 degrees C in the temperature range of -20 degrees C to 140 degrees C, resulting from the contributions of graphene and graphene oxides. In contrast, the graphene-VOx composite thin films deposited onto acrylic resin-impregnated graphite exhibit a superlinear semiconducting property of extremely low electrical resistance with negative temperature coefficients (i.e., approximately four orders of magnitude lower than that of the fused quartz), despite the similar microstructural and morphological characteristics. This difference is attributed to the synergistic effects of the paramagnetic metal feature of the tightly stacked nanowire arrays consisting of hexagonal V2O3 on the intrinsic electrical properties of the acrylic resin-impregnated graphite substrate, as revealed by FE-SEM, EDX, AFM, and XRD measurements. Although the thermo-sensitive electrical properties of the graphene-VOx composite thin films are very substrate specific, the applicability of graphene sheets can be considerably effective in the formation of highly planar arrays

  4. Annealing effects on the structural and optical properties of vanadium oxide film obtained by the hot-filament metal oxide deposition technique (HFMOD)

    Energy Technology Data Exchange (ETDEWEB)

    Scarminio, Jair; Silva, Paulo Rogerio Catarini da, E-mail: scarmini@uel.br, E-mail: prcsilva@uel.br [Universidade Estadual de Londrina (UEL), PR (Brazil). Departamento de Fisica; Gelamo, Rogerio Valentim, E-mail: rogelamo@gmail.com [Universidade Federal do Triangulo Mineiro (UFTM), Uberaba, MG (Brazil); Moraes, Mario Antonio Bica de, E-mail: bmoraes@mailhost.ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2017-01-15

    Vanadium oxide films amorphous, nonstoichiometric and highly absorbing in the optical region were deposited on ITO-coated glass and on silicon substrates, by the hot-filament metal oxide deposition technique (HFMOD) and oxidized by ex-situ annealing in a furnace at 200, 300, 400 and 500 deg C, under an atmosphere of argon and rarefied oxygen. X-ray diffraction, Raman and Rutherford backscattering spectroscopy as well as optical transmission were employed to characterize the amorphous and annealed films. When annealed at 200 and 300 deg C the as-deposited opaque films become transparent but still amorphous. Under treatments at 400 and 500 deg C a crystalline nonstoichiometric V{sub 2}O{sub 5} structure is formed. All the annealed films became semiconducting, with their optical absorption coefficients changing with the annealing temperature. An optical gap of 2.25 eV was measured for the films annealed at 400 and 500 deg C. The annealing in rarefied oxygen atmosphere proved to be a useful and simple ex-situ method to modulate the structural and optical properties of vanadium oxide films deposited by HFMOD technique. This technique could be applied to other amorphous and non-absorbing oxide films, replacing the conventional and sometimes expensive method of modulate desirable film properties by controlling the film deposition parameters. Even more, the HFMOD technique can be an inexpensive alternative to deposit metal oxide films. (author)

  5. Electrodeposition of Vanadium Oxides at Room Temperature as Cathodes in Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Michalis Rasoulis

    2017-07-01

    Full Text Available Electrodeposition of vanadium pentoxide coatings was performed at room temperature and a short growth period of 15 min based on an alkaline solution of methanol and vanadyl (III acetyl acetonate. All samples were characterized by X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The current density and electrolyte concentration were found to affect the characteristics of the as-grown coatings presenting enhanced crystallinity and porous structure at the highest values employed in both cases. The as-grown vanadium pentoxide at current density of 1.3 mA·cm−2 and electrolyte concentration of 0.5 M indicated the easiest charge transfer of Li+ across the vanadium pentoxide/electrolyte interface presenting a specific discharge capacity of 417 mAh·g−1, excellent capacitance retention of 95%, and coulombic efficiency of 94% after 1000 continuous Li+ intercalation/deintercalation scans. One may then suggest that this route is promising to prepare large area vanadium pentoxide electrodes with excellent stability and efficiency at very mild conditions.

  6. Enzymatic halogenation and oxidation using an alcohol oxidase-vanadium chloroperoxidase cascade

    NARCIS (Netherlands)

    But, Andrada; Noord, Van Aster; Poletto, Francesca; Sanders, Johan P.M.; Franssen, Maurice C.R.; Scott, Elinor L.

    2017-01-01

    The chemo-enzymatic cascade which combines alcohol oxidase from Hansenula polymorpha (AOXHp) with vanadium chloroperoxidase (VCPO), for the production of biobased nitriles from amino acids was investigated. In the first reaction H2O2 (and acetaldehyde) are generated from ethanol and oxygen by AOXHp.

  7. Rf-sputtered vanadium oxide thin films: effect of oxygen partial pressure on structural and electrochemical properties

    CERN Document Server

    Park, Y J; Ryu, K S; Chang, S H; Park, S C; Yoon, S M; Kim, D K

    2001-01-01

    Vanadium oxide thin films with thickness of about 2000 A have been prepared by radio frequency sputter deposition using a V sub 2 O sub 5 target in a mixed argon and oxygen atmosphere with different Ar/O sub 2 ratio ranging from 99/1 to 90/10. X-ray diffraction and X-ray absorption near edge structure spectroscopic studies show that the oxygen content higher than 5% crystallizes a stoichiometric V sub O sub 5 phase, while oxygen deficient phase is formed in the lower oxygen content. The oxygen content in the mixed Ar + O sub 2 has a significant influence on electrochemical lithium insertion/deinsertion property. The discharge-charge capacity of vanadium oxide film increases with increasing the reactive oxygen content. The V sub O sub 5 film deposited at the Ar/O sub 2 ratio of 90/10 exhibits high discharge capacity of 100 mu Ah/cm sup 2 -mu m along with good cycle performance.

  8. Fabrication of polypyrrole/vanadium oxide nanotube composite with enhanced electrochemical performance as cathode in rechargeable batteries

    Science.gov (United States)

    Zhou, Xiaowei; Chen, Xu; He, Taoling; Bi, Qinsong; Sun, Li; Liu, Zhu

    2017-05-01

    Vanadium oxide nanotubes (VOxNTs) with hollow as well as multi-walled features were fabricated under hydrothermal condition by soft-template method. This novel VOxNTs can be used as cathode material for lithium ion batteries (LIBs), but displaying low specific capacity and poor cycling performance owing to the residual of a mass of soft-template (C12H27N) and intrinsic low conductivity of VOx. Cation exchange technique and oxidative polymerization process of pyrrole monomers were conducted to wipe off partial soft-template without electrochemical activity within VOxNTs and simultaneously form polypyrrole coating on VOxNTs, respectively. The resulting polypyrrole/VOxNTs nanocomposite delivers much improved capacity and cyclic stability. Further optimizations, such as complete elimination of organic template and enhancing the crystallinity, can make this unique nanostructure a promising cathode for LIBs.

  9. Vanadium oxide based cpd. useful as a cathode active material - is used in lithium or alkali metal batteries to prolong life cycles

    DEFF Research Database (Denmark)

    1997-01-01

    A mixt. of metallic iron particles and vanadium pentoxide contg. V in its pentavalent state in a liq. is reacted to convert at least some of the pentavalent V to its tetravalent state and form a gel. The liq. phase is then sepd. from the oxide based gel to obtain a solid material(I) comprising Fe...

  10. Hydration effects on the molecular structure of silica-supported vanadium oxide catalysts: A combined IR, Raman, UV–vis and EXAFS study

    NARCIS (Netherlands)

    Keller, D.E.; Visser, T.|info:eu-repo/dai/nl/110288327; Soulimani, F.|info:eu-repo/dai/nl/313889449; Koningsberger, D.C.|info:eu-repo/dai/nl/073704342; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2007-01-01

    The effect of hydration on the molecular structure of silica-supported vanadium oxide catalysts with loadings of 1–16 wt.% V has been systematically investigated by infrared, Raman, UV–vis and EXAFS spectroscopy. IR and Raman spectra recorded during hydration revealed the formation of V–OH groups,

  11. Vanadium oxide/polypyrrole aerogel nanocomposites. Technical report, 1 June 1995-31 May 1996

    Energy Technology Data Exchange (ETDEWEB)

    Dave, B.C.; Bunn, B.; Leroux, F.; Nazar, L.F.; Wong, H.P.

    1996-06-18

    Vanadium pentoxide/polypyrrole aerogel (ARG) nanocomposites were prepared by hydrolysis of VO(OC3H7)3 using pyrrole/water/acetone mixtures. Monolithic green-black gels with polypyrrole/V ratios ranging from 0.15 to 1.0 resulted from simultaneous polymerization of the pyrrole and vanadium alkoxide precursors. Supercritical drying yielded high surface (150-200 sq meters/g) aerogels, of sufficient mechanical integrity to allow them to be cut without fracturing. TEM studies of the aerogels show that they are comprised of fibers similar to that of V2O5 ARG`s, but with a much shorter chain length. Evidence from IR that the inorganic and organic components strongly interact leads us to propose that this impedes the vanadium condensation process. The result is ARG`s that exhibit decreased electronic conductivity with increasing polymer content. Despite the unexpected deleterious effect of the conductive polymer on the bulk conductivity, at low polymer content, the nanocomposite materials show enhanced electrochemical properties for Li insertion compared to the pristine aerogel.

  12. Studies of vanadium-phosphorus-oxygen selective oxidation catalysts by sup 31 P and sup 51 V NMR spin-echo and volume susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Li, Juan.

    1991-10-01

    The purpose of this work is to characterize the vanadium-phosphorous oxide (V-P-O) catalysts for the selective oxidation of n-butane and 1-butene to maleic anhydride. The utility of solid state nuclear magnetic resonance as an analytical tool in this investigation lies in its sensitivity to the electronic environment surrounding the phosphorous and vanadium nuclei, and proximity of paramagnetic species. Spin-echo mapping NMR of {sup 31}p and {sup 51}v and volume magnetic susceptibility measurements were used as local microscopic probes of the presence of V{sup 5+}, V{sup 4+}, V{sup 3+} species in the model compounds: {beta}-VOPO{sub 4}, {beta}-VOPO{sub 4} treated with n-butane/1-butene, (VO){sub 2}P{sub 2}O{sub 7} treated with n-butane/1-butene; and industrial catalysts with P/V (phosphorus to vanadium) ratio of 0.9, 1.0 and 1.1, before and after treatment with n-butane and 1-butene. The NMR spectra provide a picture of how the oxidation states of vanadium are distributed in these catalysts. 73 refs., 32 figs., 8 tabs.

  13. Vanadyl precursors used to modify the properties of vanadium oxide thin films obtained by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Barreca, D.; Franzato, E.; Rizzi, G.A.; Tondello, E.; Vettori, U. [Univ. di Padova (Italy); Depero, L.E.; Sangaletti, L. [Univ. di Brescia (Italy). Dipt. di Chimica e Fisica per i Materiali

    1999-02-01

    Vanadium oxide thin films were prepared by chemical vapor deposition using as precursors a series of vanadyl complexes of general formula VO(L){sub 2}(H), where L is a {beta}-diketonate ligand. The depositions were carried out on {alpha}-Al{sub 2}O{sub 3} substrates in O{sub 2}, N{sub 2}, and N{sub 2} + H{sub 2}O atmospheres. In order to elucidate the role played by different ligands and synthesis conditions on the properties of the obtained films, the chemical composition of the samples was investigated by X-ray photoelectron spectroscopy, while their microstructure and surface morphology were analyzed by X-ray diffraction, Raman and atomic force microscopy. The thermal decomposition of the precursors, with particular attention to their reactivity in the presence of water vapor, was studied by mass spectrometry and Fourier transform infrared spectroscopy.

  14. Structural and electrical properties of different vanadium oxide phases in thin film form synthesized using pulsed laser deposition

    Science.gov (United States)

    Majid, S. S.; Shukla, D. K.; Rahman, F.; Choudhary, R. J.; Phase, D. M.

    2015-06-01

    We present here the structural and electrical properties of the thin films of V2O3 (Vanadium sesquioxide) and V5O9. Both these oxide phases, V2O3 and V5O9, have beenachieved on (001) orientedSi substrate using the V2O5 target by optimizing the deposition parameters using pulsed laser deposition technique (PLD).Deposited films were characterized by X-ray diffraction(XRD)and four probe temperature dependent resistivity measurements. XRD studies reveal the V2O3 and V5O9 phases and the amount of strain present in both these films. The temperature dependency of electrical resistivity confirmed the characteristic metal-insulator transitions (MIT) for both the films, V2O3 and V5O9.

  15. Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xinbo [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Wang, Danjun [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Li, Kebin [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Zhen, Yanzhong [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Hu, Huaiming [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Xue, Ganglin, E-mail: xglin707@163.com [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China)

    2014-09-15

    Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H{sub 2}O{sub 2}, featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalyst is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH{sub 2}) are prepared and characterized by FT-IR, XRD, N{sub 2} adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H{sub 2}O{sub 2} as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H{sub 5}[PV{sub 2}W{sub 10}O{sub 40}] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H{sub 2}O{sub 2}.

  16. Preparation and characterization of graphene-based vanadium oxide composite semiconducting films with horizontally aligned nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hye-Mi; Um, Sukkee, E-mail: sukkeeum@hanyang.ac.kr

    2016-05-01

    Highly oriented crystalline hybrid thin films primarily consisting of Magnéli-phase VO{sub 2} and conductive graphene nanoplatelets are fabricated by a sol–gel process via dipping pyrolysis. A combination of chemical, microstructural, and electrical analyses reveals that graphene oxide (GO)-templated vanadium oxide (VO{sub x}) nanocomposite films exhibit a vertically stacked multi-lamellar nanostructure consisting of horizontally aligned vanadium oxide nanowire (VNW) arrays along the (hk0) set of planes on a GO template, with an average crystallite size of 41.4 Å and a crystallographic tensile strain of 0.83%. In addition, GO-derived VO{sub x} composite semiconducting films, which have an sp{sup 3}/sp{sup 2} bonding ratio of 0.862, display thermally induced electrical switching properties in the temperature range of − 20 °C to 140 °C, with a transition temperature of approximately 65 °C. We ascribe these results to the use of GO sheets, which serve as a morphological growth template as well as an electrochemically tunable platform for enhancing the charge-carrier mobility. Moreover, the experimental studies demonstrate that graphene-based Magnéli-phase VO{sub x} composite semiconducting films can be used in advanced thermo-sensitive smart sensing/switching applications because of their outstanding thermo-electrodynamic properties and high surface charge density induced by the planar-type VNWs. - Highlights: • VO{sub x}-graphene oxide composite (G/VO{sub x}) films were fabricated by sol–gel process. • The G/VO{sub x} films mainly consisted of Magnéli-phase VO{sub 2} and reduced graphene sheets. • The G/VO{sub x} films exhibited multi-lamellar textures with planar VO{sub x} nanowire arrays. • The G/VO{sub x} films showed the thermo-sensitive electrical switching properties. • Effects of GOs on the electrical characteristics of the G/VO{sub x} films were discussed.

  17. Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Sreejesh, M. [Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Shenoy, Sulakshana [Functional Nanostructured Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Sridharan, Kishore, E-mail: kishore@nitk.edu.in [Functional Nanostructured Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India); Kufian, D.; Arof, A.K. [Centre for Ionics, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nagaraja, H.S., E-mail: nagaraja@nitk.edu.in [Materials Research Laboratory, Department of Physics, National Institute of Technology Karnataka, P.O. Srinivasnagar, Surathkal, Mangaluru 575 025 (India)

    2017-07-15

    Highlights: • Layered vanadium oxides (MVO) are prepared through melt quenching process. • MVO is hydrothermally treated with graphene oxide to form MVGO composites. • Dopamine detection capacity using MVGO is 0.07 μM with good selectivity. • Sensitivity of dopamine detection is 25.02 μA mM{sup −1} cm{sup −2}. • Discharge capacity of MVGO electrode is 200 mAhg{sup −1} after 10 cycles. - Abstract: Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM{sup −1} cm{sup −2} with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg{sup −1} at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

  18. Tunable Electrical Properties of Vanadium Oxide by Hydrogen-Plasma-Treated Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Helen Hejin Park

    2017-04-01

    Full Text Available In this study, a plasma-modified process was developed to control the electrical properties of atomic layer deposition (ALD-grown vanadium dioxide (VO2, which is potentially useful for applications such as resistive switching devices, bolometers, and plasmonic metamaterials. By inserting a plasma pulse with varying H2 gas flow into each ALD cycle, the insulator-to-metal transition (IMT temperature of postdeposition-annealed crystalline VO2 films was adjusted from 63 to 78 °C. Film analyses indicate that the tunability may arise from changes in grain boundaries, morphology, and compositional variation despite hydrogen not remaining in the annealed VO2 films. This growth method, which enables a systematic variation of the electronic behavior of VO2, provides capabilities beyond those of the conventional thermal ALD and plasma-enhanced ALD.

  19. Dehydrogenation of Isobutane with Carbon Dioxide over SBA-15-Supported Vanadium Oxide Catalysts

    Directory of Open Access Journals (Sweden)

    Chunling Wei

    2016-10-01

    Full Text Available A series of vanadia catalysts supported on SBA-15 (V/SBA with a vanadia (V content ranging from 1% to 11% were prepared by an incipient wetness method. Their catalytic behavior in the dehydrogenation of isobutane to isobutene with CO2 was examined. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, and temperature-programmed reduction (TPR. It was found that these catalysts were effective for the dehydrogenation reaction, and the catalytic activity is correlated with the amount of dispersed vanadium species on the SBA-15 support. The 7% V/SBA catalyst shows the highest activity, which gives 40.8% isobutane conversion and 84.8% isobutene selectivity. The SBA-15-supported vanadia exhibits higher isobutane conversion and isobutene selectivity than the MCM-41-supported one.

  20. Synergistic effect of 3,5-dichlorophenol and trioctylphosphine oxide on the extraction of vanadium(V) with 2-methyl-8-quinolinol derivatives.

    Science.gov (United States)

    Tsuguchi, Akira; Ohashi, Akira; Choi, Sung-Yong; Imura, Hisanori; Ohashi, Kousaburo

    2002-11-01

    The extraction of vanadium(V) with 2-methyl-8-quinolinol derivatives (HA), such as 2-methyl-8-quinolinol (HMQ), 2-methyl-5-butyloxymethyl-8-quinolinol (HMO4Q), and 2-methyl-5-hexyloxymethyl-8-quinolinol (HMO6Q), from a weakly acidic solution into chloroform was studied in both the absence and presence of 3,5-dichlorophenol (Hdcp) and trioctylphosphine oxide (TOPO) as the synergists. Vanadium(V) was extracted with HA as VO(OH)(A)2 in the absence of synergists, and its extractability increased with an increase in the hydrophobicity of HA. Vanadium(V) was quantitatively extracted from the lower pH region upon the addition of Hdcp and TOPO as VO(OH)(A)2 x Hdcp and VO2(A)(TOPO), respectively. The enhancement of the synergistic effect of Hdcp on the extraction of vanadium(V) with HA increased in the following order: HMQ < HMO4Q < HMO6Q, as opposed to that of TOPO. This result was ascribable to the difference in the mechanisms of the occurrence of the synergistic effect by Hdcp and TOPO.

  1. VANADIUM ALLOYS

    Science.gov (United States)

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  2. Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(V)Oxide as a PEDOT:PSS Replacement

    DEFF Research Database (Denmark)

    Martinez, Nieves Espinosa; Dam, Henrik Friis; Tanenbaum, David M.

    2011-01-01

    The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full...... roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V2O5·(H2O)n/Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium...... to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker....

  3. Electronic Excitations in Vanadium Oxide Phthalocyanine Studied via Resonant Soft X-ray Emission and Resonant Inelastic X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang,Y.; Wang, S.; Learmonth, T.; Plucinski, L.; Matsuura, A.; Bernardis, S.; ODonnell, C.; Downes, J.; Smith, K.

    2005-01-01

    The electronic structure of the organic semiconductor vanadium oxide phthalocyanine has been studied using resonant inelastic X-ray scattering and X-ray emission spectroscopy. The vanadyl species in the films is shown to be highly localized, and good agreement between the measurements and a density functional calculation is obtained. Both dipole forbidden V 3d to V 3d*, and O 2p to V 3d* charge transfer transitions are observed, and explained in a local molecular orbital model.

  4. Electro-optical evaluation of tungsten oxide and vanadium pentoxide thin films for modeling an electrochromic device

    Directory of Open Access Journals (Sweden)

    H Najafi Ashtiani

    2015-01-01

    Full Text Available In this study, tungsten oxide and vanadium oxide electrochromic thin films were placed in vacuum and in a thickness of 200 nm on a transparent conductive substrate of SnO2:F using the physical method of thermal evaporation. Then they were studied for the optical characteristics in the wavelength range from 400 to 700 nm and for their electrical potentials in the range form +1.5 to -1.5 volts. The films were post heated in order to assess changes in energy gap with temperature, at temperatures120 , 300 and 500°C. Refractive and extinction coefficients and the transition type of films in the visible light range and in the thickness of 200 nm were determined and measured. X-ray diffraction pattern and SEM images and cyclic Voltammetry of layers were also studied. The results of this study due to the deposition of layers, the layer thickness selected, the type of substrate, the range of annealing temperatures and selected electrolyte were in full compliance with the works of other researchers [1,2,3]. Therefore, these layers with features such as crystal structure, refractive and even extinction coefficients in the range of visible light, the appropriate response of chromic switch in the replication potential, good adhesion to the substrate, and the high amount of optical transmition and so on, prove useful to be used in an electrochromic device

  5. 51V Solid-state NMR and Density-Functional Theory Studies of Eight-Coordinate Non-Oxo Vanadium Complexes: Oxidized Amavadin

    Science.gov (United States)

    Ooms, Kristopher J.; Bolte, Stephanie E.; Baruah, Bharat; Choudhary, Muhammad Aziz; Crans, Debbie C.; Polenova, Tatyana

    2014-01-01

    SUMMARY Using 51V magic angle spinning solid-state NMR spectroscopy and Density Functional Theory calculations we have characterized the chemical shift and quadrupolar coupling parameters for two eight-coordinate vanadium complexes, [PPh4][V(V)(HIDPA)2] and [PPh4][V(V)(HIDA)2]; HIDPA = 2,2′-(hydroxyimino)dipropionate and HIDA = 2,2′-(hydroxyimino)diacetate. The coordination geometry under examination is the less common non-oxo eight coordinate distorted dodecahedral geometry that has not been previously investigated by solid-state NMR spectroscopy. Both complexes were isolated by oxidizing their reduced forms: [V(IV)(HIDPA)2]2- and [V(IV)(HIDA)2]2-. V(IV)(HIDPA)22- is also known as amavadin, a vanadium-containing natural product present in the Amanita muscaria mushroom and responsible for vanadium accumulation in nature. The quadrupolar coupling constants, CQ, are found to be moderate, 5.0 to 6.4 MHz while the chemical shift anisotropies are relatively small for vanadium complexes, −420 and 360 ppm. The isotropic chemical shifts in the solid state are −220 and −228 ppm for the two compounds, and near the chemical shifts observed in solution. Presumably this is a consequence of the combined effects of the increased coordination number and the absence of oxo groups. Density Functional Theory calculations of the electric field gradient parameters are in good agreement with the NMR results while the chemical shift parameters show some deviation from the experimental values. Future work on this unusual coordination geometry and a combined analysis by solid-state NMR and Density Functional Theory should provide a better understanding of the correlations between experimental NMR parameters and the local structure of the vanadium centers. PMID:19421628

  6. Organic ligand induced release of vanadium from the dissolution of stone coal oxide ore.

    Science.gov (United States)

    Hu, Xingyun; Yue, Yuyan; Peng, Xianjia

    2017-10-02

    The effects of low-molecular-weight dissolved organic matters (LMWDOMs) on the release of vanadium (V) under environmental conditions are part of a broader study on the environmental geochemistry behavior of V. Eight typical naturally occurring LMWDOMs with carboxyl, hydroxyl, and amidogen groups were chosen: citric acid, oxalic acid, EDTA, salicylic acid, catechol, glycine, cysteine, and glucose. The results showed that the release of V was largely promoted by LMWDOMs with carboxyl functional groups under acidic conditions and with catechol under basic conditions. In the presence of citric acid, oxalic acid, or EDTA at pH 4.0, the initial release rates of V were approximately 25-39 times greater than the rates in the control experiments; the steady release rates were 164, 95, and 49 times than the rates in the control experiments, respectively. For catechol, the release rate at pH 8.0 was approximately 20 times the rate at pH 4.0. Amino acids and alcohols had a minimal effect on the release of V. Ligand-promoted release rates of V were found primarily due to the faster detachment of surface complexes, the protonated sites from the mineral surface and the reduction of dissolved V (V) in the presence of citric acid, oxalic acid, EDTA, and catechol. This study helps understand the pollution risk of V in some mine areas and the fate of V in the environment.

  7. Selective nano alumina supported vanadium oxide catalysts for oxidative dehydrogenation of ethylbenzene to styrene using CO2 as soft oxidant

    Directory of Open Access Journals (Sweden)

    A.M. Elfadly

    2013-12-01

    Full Text Available Nano alumina-supported V2O5 catalysts with different loadings have been tested for the dehydrogenation of ethylbenzene with CO2 as an oxidant. High surface area nano-alumina was prepared and used as support for V2O5 as the catalyst. The catalysts were synthesized by impregnation techniques followed by calcinations and microwave treatment, denoted as V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW, respectively. The V2O5 loading was varied on nano-alumina from 5 to 30 wt%. The support and catalysts were characterized by X-ray diffraction (XRD, Barett–Joyner–Halenda (BJH pore-size distribution, N2-adsorption isotherms, Fourier transform infrared (FT-IR, scanning electron microscopy (SEM, transmission electron microscopy (TEM and temperature programed desorption (TPD-NH3. The characterization results indicated that V2O5 is highly dispersed on alumina up to 30%-V2O5/γ-Al2O3-MW prepared by MW method. The TPD studies indicated that there are significant differences in acid amount and strength for V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW-catalysts. The catalytic activity of the prepared catalysts was evaluated in the temperature range 450–600 °C in relation to the physicochemical properties and surface acidity. The results revealed that optimum catalytic activity and selectivity (∼100% toward styrene production were obtained using 10% V2O5/γ-Al2O3-MW catalyst treated with microwave.

  8. Study of the performance of vanadium based catalysts prepared by grafting in the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Santacesaria, E.; Carotenuto, G.; Tesser, R.; Di Serio, M. [Naples Univ. (Italy). Dept. of Chemistry

    2011-07-01

    The oxidative dehydrogenation (ODH) of propane has been investigated by using many different vanadia based catalysts, prepared by grafting technique and containing variable amounts of active phase supported on SiO{sub 2} previously coated, by grafting in three different steps, with multilayer of TiO{sub 2}. A depth catalytic screening, conducted in a temperature range of 400-600 C, at atmospheric pressure and in a range of residence time W/F=0.08-0.33 ghmol{sub -1}, has shown that the vanadium oxide catalysts on TiO{sub 2}-SiO{sub 2} support, prepared by grafting have good performances in the ODH of propane. In particular, a preliminary study has demonstrated that higher selectivities can be obtained employing catalysts having a well dispersed active phase that can be achieved with a V{sub 2}O{sub 5} content lower than 10%{sub w}t. It is well known that, in the case of redox catalysts, an increase of the selectivity can be achieved not only by using an adequate catalytic system but also via engineering routes like decoupling catalytic steps of reduction and re-oxidation. In fact it has been observed that by operating in dehydrogenating mode, on the same catalysts, a higher selectivity is obtained although the catalyst is poisoned by the formation of coke on the surface. As consequence of the results obtained in dehydrogenation, in this work has been explored the possibility to feed low amounts of oxygen, below the stoichiometric level with the aim to keep clean the surface from coke but maintaining high the selectivity, because, dehydrogenation reaction prevails. In this work, the behavior of catalysts containing different amounts of V2O5 has been studied in the propane-propene reaction by using different ratios C{sub 3}H{sub 8}/O{sub 2} included in the range 0-2. (orig.)

  9. Influence of oxygen flow rate on metal-insulator transition of vanadium oxide thin films grown by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xu; Liu, Xinkun; Li, Haizhu; Huang, Mingju [Henan University, Key Lab of Informational Opto-Electronical Materials and Apparatus, School of Physics and Electronics, Kaifeng (China); Zhang, Angran [South China Normal University, Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, Guangzhou (China)

    2017-03-15

    High-quality vanadium oxide (VO{sub 2}) films have been fabricated on Si (111) substrates by radio frequency (RF) magnetron sputtering deposition method. The sheet resistance of VO{sub 2} has a significant change (close to 5 orders of magnitude) in the process of the metal-insulator phase transition (MIT). The field emission-scanning electron microscope (FE-SEM) results show the grain size of VO{sub 2} thin films is larger with the increase of oxygen flow. The X-ray diffraction (XRD) results indicate the thin films fabricated at different oxygen flow rates grow along the (011) crystalline orientation. As the oxygen flow rate increases from 3 sccm to 6 sccm, the phase transition temperature of the films reduces from 341 to 320 K, the width of the thermal hysteresis loop decreases from 32 to 9 K. The thin films fabricated in the condition of 5 sccm have a high temperature coefficient of resistance (TCR) -3.455%/K with a small resistivity of 2.795 ρ/Ω cm. (orig.)

  10. Vanadium Oxide Supported on MSU-1 as a Highly Active Catalyst for Dehydrogenation of Isobutane with CO2

    Directory of Open Access Journals (Sweden)

    Guosong Sun

    2016-03-01

    Full Text Available Vanadium oxide supported on MSU-1, with VOx loading ranging from 2.5 to 17.5 wt. %, was developed as a highly active catalyst in dehydrogenation of isobutane with CO2. The obtained catalysts of VOx/MSU-1 were characterized by X-ray diffraction (XRD, N2 adsorption-desorption, and H2-temperature programmed reduction (H2-TPR methods and the results showed that the large surface area of MSU-1 was favorable for the dispersion of VOx species and the optimal loading of VOx was 12.0 wt. %. Meanwhile, the catalytic activity of VOx/MSU-1 was investigated, and VOx/MSU-1 with 12.0 wt. % VOx content was found to be the best one, with the conversion of isobutane (58.8% and the selectivity of isobutene (78.5% under the optimal reaction conditions. In contrast with the reaction in the absence of CO2, the presence of CO2 in the reaction stream could obviously enhance the isobutane dehydrogenation, which raised the conversion of reaction and the stability of VOx/MSU-1.

  11. Controlling interlayer interactions in vanadium pentoxide-poly(ethylene oxide) nanocomposites for enhanced magnesium-ion charge transport and storage

    Science.gov (United States)

    Perera, Sanjaya D.; Archer, Randall B.; Damin, Craig A.; Mendoza-Cruz, Rubén; Rhodes, Christopher P.

    2017-03-01

    Rechargeable magnesium batteries provide the potential for lower cost and improved safety compared with lithium-ion batteries, however obtaining cathode materials with highly reversible Mg-ion capacities is hindered by the high polarizability of divalent Mg-ions and slow solid-state Mg-ion diffusion. We report that incorporating poly(ethylene oxide) (PEO) between the layers of hydrated vanadium pentoxide (V2O5) xerogels results in significantly improved reversible Mg-ion capacities. X-ray diffraction and high resolution transmission electron microscopy show that the interlayer spacing between V2O5 layers was increased by PEO incorporation. Vibrational spectroscopy supports that the polymer interacts with the V2O5 lattice. The V2O5-PEO nanocomposite exhibited a 5-fold enhancement in Mg-ion capacity, improved stability, and improved rate capabilities compared with V2O5 xerogels. The Mg-ion diffusion coefficient of the nanocomposite was increased compared with that of V2O5 xerogels which is attributed to enhanced Mg-ion mobility due to the shielding interaction of PEO with the V2O5 lattice. This study shows that beyond only interlayer spacing, the nature of interlayer interactions of Mg-ions with V2O5, PEO, and H2O are key factors that affect Mg-ion charge transport and storage in layered materials. The design of layered materials with controlled interlayer interactions provides a new approach to develop improved cathodes for magnesium batteries.

  12. Interplay of electron-electron and electron-phonon interaction in the metal to insulator transition in vanadium oxides.

    Energy Technology Data Exchange (ETDEWEB)

    Baldassarre, Leonetta [CNR-INFM COHERENTIA, Roma (Italy); Experimentalphysik II, Universitaet Augsburg (Germany); Department of Physics, University of Rome ' La Sapienza' (Italy); Arcangeletti, Emanuele; Perucchi, Andrea; Nicoletti, Daniele; Di Castro, Daniele; Marini, Carlo; Postorino, Paolo; Lupi, Stefano [CNR-INFM COHERENTIA, Roma (Italy); Department of Physics, University of Rome ' La Sapienza' (Italy)

    2008-07-01

    Several families of vanadium oxides display metal to insulator transitions (MIT) often driven by both temperature (T) and pressure (P) with jumps of conductivity up to 7 orders of magnitude. While the transition in V{sub 2}O{sub 3} is considered as induced mainly by electronic correlation (Mott-Hubbard transition), the MIT mechanism that drives the electronic transition in VO{sub 2} is still unclear, probably determined by an interplay between electronic and lattice degrees of freedom. Here we present a complete investigation of MIT as a function of T and P of V{sub 2}O{sub 3} and VO{sub 2}. Infrared measurements have been performed in a wide range of T (10-600 K) and P (0-15 GPa) in order to cover the rich phase diagrams of those materials. P-dependent Raman measurements have also been performed on VO{sub 2} so to follow also the lattice dynamics. Moreover, the high temperature incoherent phase is discussed in V{sub 2}O{sub 3}, the ideal playground to study the correlation effects on the low-energy electrodynamics.

  13. Elucidation of the molecular structure of hydrated vanadium oxide species by X-ray absorption spectroscopy: correlation between the V--V coordination number and distance and the point of zero charge of the support oxide

    OpenAIRE

    Keller, D. E.; Koningsberger, D.C.; Weckhuysen, B. M.

    2006-01-01

    The effect of the point of zero charge (PZC) of the support oxide (Al(2)O(3), Nb(2)O(5), SiO(2) and ZrO(2)) on the molecular structure of hydrated vanadium oxide species has been investigated with EXAFS spectroscopy for low-loaded vanadium oxide catalysts. It was found that the degree of clustering (i.e., the V[dot dot dot]V coordination number) and the V...V distance increase with decreasing PZC of the support oxide; i.e., Al(2)O(3) (8.7) < ZrO(2) (7) < Nb(2)O(5) (3.3) < SiO(2) (2). Upon hyd...

  14. Effect of citric acid dosage and sintered temperature on the composition, morphology and electrochemical properties of lithium vanadium oxide prepared by a sol-gel method

    Science.gov (United States)

    Zhong, C. R.; Su, X. J.; Hou, G. L.; Liu, Z. H.; Yu, F. S.; Bi, S.; Li, H.

    2017-03-01

    A lithium vanadium oxide cathode material was synthesized via sol-gel processing using citric acid as the chelating agent. Different dosage of citric acid and sintered temperature were introduced to investigate their effects on the products composition, morphology and electrochemical properties. The results showed that the V2O3 yield was inhibited and the crystallization of grain was accelerated with the increasing dosage of citric acid. Furthermore, V2O3 was oxidized to LiV3O8 and Li0.3V2O5 with the increase of sintered temperature.

  15. Fabrication of polypyrrole/vanadium oxide nanotube composite with enhanced electrochemical performance as cathode in rechargeable batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaowei, E-mail: zhouxiaowei@ynu.edu.cn [Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650504, Yunnan (China); Chen, Xu; He, Taoling; Bi, Qinsong [Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650504, Yunnan (China); Sun, Li [Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650504, Yunnan (China); Department of Mechanical Engineering, University of Houston, Houston 77204, TX (United States); Liu, Zhu, E-mail: zhuliu@ynu.edu.cn [Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650504, Yunnan (China); Yunnan Key Laboratory of Micro/Nano-Materials and Technology, Yunnan University, Kunming 650091, Yunnan (China)

    2017-05-31

    Highlights: • VO{sub x}NTs were hydrothermally prepared using C{sub 12}H{sub 27}N as soft template with scalability. • Polypyrrole/VO{sub x}NTs with less C{sub 12}H{sub 27}N template and higher conductivity were obtained. • Polypyrrole/VO{sub x}NTs exhibit better performance as cathode for LIBs compared to VO{sub x}NTs. • Further modification to VO{sub x}NTs with desired electrochemical property can be expected. - Abstract: Vanadium oxide nanotubes (VO{sub x}NTs) with hollow as well as multi-walled features were fabricated under hydrothermal condition by soft-template method. This novel VO{sub x}NTs can be used as cathode material for lithium ion batteries (LIBs), but displaying low specific capacity and poor cycling performance owing to the residual of a mass of soft-template (C{sub 12}H{sub 27}N) and intrinsic low conductivity of VO{sub x}. Cation exchange technique and oxidative polymerization process of pyrrole monomers were conducted to wipe off partial soft-template without electrochemical activity within VO{sub x}NTs and simultaneously form polypyrrole coating on VO{sub x}NTs, respectively. The resulting polypyrrole/VO{sub x}NTs nanocomposite delivers much improved capacity and cyclic stability. Further optimizations, such as complete elimination of organic template and enhancing the crystallinity, can make this unique nanostructure a promising cathode for LIBs.

  16. Solid solution formation between vanadium(V) and tungsten(V) oxide phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Subrata Chandra; Glaum, Robert [Institut fuer Anorganische Chemie, Rheinische Friedrich-Wilhelms-Universitaet Bonn (Germany); Abdullin, Dinar; Schiemann, Olav [Institut fuer Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universitaet Bonn (Germany); Bac, Nguyen Quang; Lii, Kwang-Hwa [Department of Chemistry, National Central University, Jhongli, Taiwan (China)

    2014-08-15

    The solid solutions (V{sub 1-x}W{sub x})OPO{sub 4} with β-VOPO{sub 4} structure type (0.0 ≤ x ≤ 0.01) and α{sub II}-VOPO{sub 4} structure type (0.04 ≤ x ≤ 0.26) were obtained from mixtures of V{sup V}OPO{sub 4} and W{sup V}OPO{sub 4} by conventional solid state reactions and by solution combustion synthesis. Single crystals of up to 3 mm edge length were obtained by chemical vapor transport (CVT) (800 → 700 C, Cl{sub 2} as a transporting agent). Single crystal structure refinements of crystals at x = 0.10 [a = 6.0503(2) Aa, c = 4.3618(4) Aa, R{sub 1} = 0.021, wR{sub 2} = 0.058, 21 parameters, 344 independent reflections] and x = 0.26 [a = 6.0979(2) Aa, c = 4.2995(1) Aa, R{sub 1} = 0.030, wR{sub 2} = 0.081, 21 parameters, 346 independent reflections] confirm the α{sub II}-VOPO{sub 4} structure type (P4/n, Z = 2) with mixed occupancy V/W for the metal site. Due to the specific redox behavior of W{sup 5+} and V{sup 5+}, solid solutions (V{sub 1-x}W{sub x})OPO{sub 4} should be formulated as (V{sup IV}{sub x}V{sup V}{sub 1-2x}W{sup VI}{sub x})OPO{sub 4}. The valence states of vanadium and tungsten are confirmed by XPS measurements. V{sup 4+} with d{sup 1} configuration was identified by EPR spectroscopy and magnetic measurements. Electronic spectra of the solid solutions show the IVCT(V{sup 4+} → V{sup 5+}) and the LMCT(O{sup 2-} → V{sup 5+}). (V{sub 0.74}W{sub 0.26})OPO{sub 4} powders exhibit semi-conducting behavior (E{sub g} = 0.7 eV). (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Vanadium(IV/V) speciation of pyridine-2,6-dicarboxylic acid and 4-hydroxy-pyridine-2,6-dicarboxylic acid complexes: potentiometry, EPR spectroscopy and comparison across oxidation states.

    Science.gov (United States)

    Jakusch, Tamás; Jin, Wenzheng; Yang, Luqin; Kiss, Tamás; Crans, Debbie C

    2003-05-01

    Evaluation of stability of vanadium(IV) and (V) complexes under similar conditions is critical for the interpretation and assessment of bioactivity of various vanadium species. Detailed understanding of the chemical properties of these complexes is necessary to explain differences observed their activity in biological systems. These studies are carried out to link the chemistry of both vanadium(IV) and (V) complexes of two ligands, 2,6-pyridinedicarboxylic acid (dipicolinic acid, H(2)dipic) and 4-hydroxy-2,6-pyridinedicarboxylic acid (H(2)dipic-OH). Solution speciation of the two 2,6-pyridinedicarboxylic acids with vanadium(IV) and vanadium(V) ions was determined by pH-potentiometry at I=0.2 M (KCl) ionic strength and at T=298 K. The stability and the metal affinities of the ligands were compared. Vanadium(V) complexes were found to form only tridentate coordinated 1:1 complexes, while vanadium(IV) formed complexes with both 1:1 and 1:2 stoichiometries. The formation constant reflects hindered coordination of a second ligand molecule, presumably because of the relatively small size of the metal ion. The most probable binding mode of the complexes was further explored using ambient and low temperature EPR spectroscopy for vanadium(IV) and 51V NMR spectroscopy for vanadium(V) systems. Upon complex formation the pyridinol-OH in position 4 deprotonates with pK approximately 3.7-4.1, which is approximately 6 orders of magnitude lower than that of the free ligand. The deprotonation enhances the ligand metal ion affinity compared to the parent ligand dipicolinic acid. In the light of the speciation and stability data of the metal complexes, the efficiency of the two ligands in transporting the metal ion in the two different oxidation states are assessed and discussed.

  18. Thermal oxidation of vanadium-free Ti alloys: An X-ray photoelectron spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Maria Francisca, E-mail: mflopez@icmm.csic.es [Department of Surfaces and Coatings, ICMM-CSIC, Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049 Madrid (Spain); Gutierrez, Alejandro [Departamento de Fisica Aplicada and Instituto Nicolas Cabrera, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Jimenez, Jose Antonio [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda. Gregorio del Amo 8, E-28040 Madrid (Spain); Martinesi, Maria; Stio, Maria; Treves, Cristina [Department of Biochemical Sciences of University of Florence, Viale Morgagni 50, 50134 Florence (Italy)

    2010-04-06

    In the present work, X-ray photoelectron spectroscopy (XPS) was used to study the surface chemical composition of three alloys for biomedical applications: Ti-7Nb-6Al, Ti-13Nb-13Zr and Ti-15Zr-4Nb. The surface of these alloys was modified by annealing in air at 750 deg. C for different times with the aim of developing an oxide thick layer on top. The evolution of surface composition with annealing time was studied by XPS, and compared with the composition of the native oxide layer present on the samples before annealing. Two different oxidation trends were observed depending on the alloying elements and their corresponding diffusion kinetics, which give rise to different chemical species at the topmost layers. These results were linked with an evaluation of the biological response of the alloys by bringing them in contact with human peripheral blood mononuclear cells (PBMC).

  19. Melt quenched vanadium oxide embedded in graphene oxide sheets as composite electrodes for amperometric dopamine sensing and lithium ion battery applications

    Science.gov (United States)

    Sreejesh, M.; Shenoy, Sulakshana; Sridharan, Kishore; Kufian, D.; Arof, A. K.; Nagaraja, H. S.

    2017-07-01

    Electrochemical sensors and lithium-ion batteries are two important topics in electrochemistry that have attracted much attention owing to their extensive applications in enzyme-free biosensors and portable electronic devices. Herein, we report a simple hydrothermal approach for synthesizing composites of melt quenched vanadium oxide embedded on graphene oxide of equal proportion (MVGO50) for the fabrication of electrodes for nonenzymatic amperometic dopamine sensor and lithium-ion battery applications. The sensing performance of MVGO50 electrodes through chronoamperometry studies in 0.1 M PBS solution (at pH 7) over a wide range of dopamine concentration exhibited a highest sensitivity of 25.02 μA mM-1 cm-2 with the lowest detection limit of 0.07 μM. In addition, the selective sensing capability of MVGO50 was also tested through chronoamperometry studies by the addition of a very small concentration of dopamine (10 μM) in the presence of a fairly higher concentration of uric acid (10 mM) as the interfering species. Furthermore, the reversible lithium cycling properties of MVGO50 are evaluated by galvanostatic charge-discharge cycling studies. MVGO50 electrodes exhibited enhanced rate capacity of up to 200 mAhg-1 at a current of 0.1C rate and remained stable during cycling. These results indicate that MVGO composites are potential candidates for electrochemical device applications.

  20. Performance enhancement of reduced graphene oxide-modified carbon electrodes for vanadium redox-flow systems

    NARCIS (Netherlands)

    Chakrabarti, B.; Nir, D.; Yufit, V; Tariq, F; Rubio-Garcia, J.; Maher, R.; Kucernak, A.; Purushothaman Vellayani, A.; Brandon, N.

    2017-01-01

    Reduced graphene oxide (rGO) suspended in an N,N′-dimethylformamide (DMF) solvent underwent electrophoretic deposition (EPD) on carbon paper (CP) electrodes. X-ray computed micro-tomography (XMT) indicates a 24 % increase in the specific surface area of CP modified with rGO in comparison to the

  1. Kinetics of oxidation of D-arabinose and D-xylose by vanadium (V in the presence of manganese II as homogeneous catalyst

    Directory of Open Access Journals (Sweden)

    Ezekiel O. Odebunmi

    2010-12-01

    Full Text Available Kinetics of oxidation of D-arabinose and D-xylose by acidic solution of vanadium (V ions in the presence of manganese (II has been reported. First-order dependence of the reaction rate was observed on [sugars] and [H+] at low concentrations throughout the oxidation reaction and a zero-order dependence on [sugar] and [H+] was observed at high concentrations. First-order kinetics with respect to [Mn (II] was also observed throughout the oxidation for both sugars. The results indicate the effect of Cl- concentration is negligible. The reaction rates increase with the ionic strength of the medium. Various activation parameters were evaluated and provide further support to the proposed mechanism. Formic acid was reported as one of the oxidation products of these sugars.

  2. Fundamental Studies of Butane Oxidation over Model-Supported Vanadium Oxide Catalysts: Molecular Structure-Reactivity Relationships

    NARCIS (Netherlands)

    Wachs, I.E.; Jehng, J.M.; Deo, G.; Weckhuysen, B.M.; Guliants, V.V.; Benziger, J.B.; Sundaresan, S.

    1997-01-01

    The oxidation of n-butane to maleic anhydride was investigated over a series of model-supported vanadia catalysts where the vanadia phase was present as a two-dimensional metal oxide overlayer on the different oxide supports (TiO2, ZrO2, CeO2, Nb2O5, Al2O3, and SiO2). No correlation was found

  3. Study of thermal degradation of vanadium and titanium acetylacetonate derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Dyagileva, L.M.; Tsyganova, E.I.; Mar' in, V.P.; Aleksandrov, Yu.A. (Gor' kovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Khimii)

    1982-09-01

    Kinetics and products of vanadium (+3), vanadyl (+3) and titanium (+3) acetylacetonates thermal degradation have been studied in vapor phase in the closed system at 300-470 deg C. Gaseous composition of pyrolysis has been determined at different levels of decomposition. It is supposed that vanadium and metal vanadium mixed oxides become vanadium (+3) pyrolysis products. It is shown that metal oxidation level does not affect the thermal degradation rate. Central atom substitution leads to the change in thermal stability. Titanium (+3) acetylacetate derivatives are less stable than vanadium (+3) ones.

  4. The future of/for vanadium.

    Science.gov (United States)

    Rehder, Dieter

    2013-09-07

    Vanadium compounds are stored or employed by several groups of bacterial and eukaryotic organisms. Two types of vanadium-dependent enzymes have so far been characterised: vanadate-dependent haloperoxidases from fungi, lichens, marine macroalgae and Streptomyces bacteria, and vanadium nitrogenases in proteo- and cyanobacteria. Several bacterial strains can employ vanadate(V) as an external electron acceptor in respiration, reducing vanadate to VO(2+) and thus contributing to the mineralisation of vanadium and to the detoxification of vanadate-contaminated water. Amanita mushrooms and many sea squirts accumulate vanadium, without the importance of this practise being well understood. Further, the analogy between vanadate and phosphate implicates an interference of vanadate with metabolic processes involving phosphate, suggesting a regulatory role for vanadate in most if not all organisms, including humans, but also hinting at toxic effects at unphysiologically high vanadate concentrations. The antidiabetic effect of vanadium compounds is probably related to the phosphate-vanadate antagonism, as is the potentiality of vanadate in the amelioration of cardiovascular affliction. The anti-cancer action of vanadium compounds and their in vitro activity towards the protozoa causing amoebiasis, leishmaniasis and Chagas' disease again may be rooted in the intervention of vanadate with the activity of phosphatases and kinases. In addition, most likely the ability of vanadate(V) and oxidovanadium(IV) to regulate the cellular production of reactive oxygen species comes in, thus influencing cellular signalling. Future developments of vanadium chemistry are likely to emphasize topics related to biological, environmental and medicinal aspects. Condensation of monovanadate results in the formation of oligovanadates, polyvanadates and finally colloidal and solid vanadium oxides that, in part, convey bio-mimetic functions comparable to those of simple vanadate, including its catalytic

  5. Vanadium and molybdenum oxide thin films on Au(111). Growth and surface characterization

    Energy Technology Data Exchange (ETDEWEB)

    Guimond, Sebastien

    2009-06-04

    The growth and the surface structure of well-ordered V{sub 2}O{sub 3}, V{sub 2}O{sub 5} and MoO{sub 3} thin films have been investigated in this work. These films are seen as model systems for the study of elementary reaction steps occurring on vanadia and molybdena-based selective oxidation catalysts. It is shown that well-ordered V{sub 2}O{sub 3}(0001) thin films can be prepared on Au(111). The films are terminated by vanadyl groups which are not part of the V{sub 2}O{sub 3} bulk structure. Electron irradiation specifically removes the oxygen atoms of the vanadyl groups, resulting in a V-terminated surface. The fraction of removed vanadyl groups is controlled by the electron dose. Such surfaces constitute interesting models to probe the relative role of both the vanadyl groups and the undercoordinated V ions at the surface of vanadia catalysts. The growth of well-ordered V{sub 2}O{sub 5}(001) and MoO{sub 3}(010) thin films containing few point defects is reported here for the first time. These films were grown on Au(111) by oxidation under 50 mbar O{sub 2} in a dedicated high pressure cell. Contrary to some of the results found in the literature, the films are not easily reduced by annealing in UHV. This evidences the contribution of radiation and surface contamination in some of the reported thermal reduction experiments. The growth of ultrathin V{sub 2}O{sub 5} and MoO{sub 3} layers on Au(111) results in formation of interface-specific monolayer structures. These layers are coincidence lattices and they do not correspond to any known oxide bulk structure. They are assumed to be stabilized by electronic interaction with Au(111). Their formation illustrates the polymorphic character and the ease of coordination units rearrangement which are characteristic of both oxides. The formation of a second layer apparently precedes the growth of bulk-like crystallites for both oxides. This observation is at odds with a common assumption that crystals nucleate as soon as a

  6. Toward binder-free electrochemical capacitor electrodes of vanadium oxide-nanostructured carbon by supercritical fluid deposition: Precursor adsorption and conversion, and electrode performance

    Science.gov (United States)

    Do, Quyet H.; Smithyman, Jesse; Zeng, Changchun; Zhang, Chuck; Liang, Richard; Zheng, Jim P.

    2014-02-01

    Electrochemical capacitor electrodes were fabricated by depositing an ultra-thin layer of vanadium oxide on a high conducting, large specific surface area (SSA) materials (substrates) using a supercritical fluid adsorption-calcination method. The high SSA materials included binder free single walled carbon nanotube-activated carbon (SWCNT-AC) composites and the traditional electrode of activated carbon-carbon black-polymer binder (AC-CB-binder). The uptake of the organometallic precursor for the oxide (vanadium (III) acetylacetonate) on the substrates were investigated and related to their SSA. Precursor uptakes up to 54.7 wt% of the initial carbon substrate was achieved. Calcination conditions for converting the precursor to oxide and electrochemical properties of the electrodes were thoroughly investigated. The V2O5, which showed extremely high specific pseudo-capacitance (>1000 F g-1 at 100 mV s-1), greatly enhanced the overall electrode performances. Conversely, the V2O5 pseudo-capacitance was better utilized in the SWCNT-AC substrate, particularly at high working speeds, because of the significantly higher electrical conductivity. For example, the SWCNT-AC-V2O5 composite (weight ratio 40:60) had its volumetric capacitance doubled, comparing to the ∼50% increase in the AC-CB-binder sample at 100 mV s-1.

  7. Titanium–vanadium oxide nanocomposite thin films: Synthesis, characterization and antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Wren, A.W.; Adams, B.M.; Pradhan, D.; Towler, M.R.; Mellott, N.P., E-mail: mellott@alfred.edu

    2014-04-01

    A sol–gel based deposition method was successfully developed to produce a series of crack-free, spatially homogeneous undoped/silver doped titania–vanadia oxide nanocomposite thin films. Thin films were characterized using Glancing Incidence X-ray Diffraction (GIXRD), X-ray Photoelectron Spectroscopy (XPS), and Ultraviolet Visible Spectroscopy (UV–Vis). It was determined via both XRD and XPS that when calcined at 450 °C the nanocomposite crystallinity was a function of sol composition. Additionally, it was determined via GIXRD that upon silver doping, silver was incorporated into the vanadia structure or present in silver oxide form in crystalline films. A red shift within the UV–Vis spectra was observed with an increase of vanadia concentration from 0 to 100% respectively. Antibacterial analysis conducted on Escherichia coli and Staphylococcus epidermidis demonstrated that films exposed to light showed greater antibacterial properties. - Highlights: • Nanocomposite crystallinity was a function of sol composition. • Silver was incorporated into the vanadia structure. • A red shift was observed with an increase of vanadia concentration. • Antibacterial analysis conducted on Escherichia coli and Staphylococcus epidermidis.

  8. The Development of a New Kinetic Spectrophotometric Method for the Determination of Vanadium(V Based on its Catalytic Effect on the Oxidation of Malachite Green Oxalate by Bromate in Acidic and Micellar Medium

    Directory of Open Access Journals (Sweden)

    M. Keyvanfard

    2010-01-01

    Full Text Available A new, simple, sensitive and selective kinetic spectrophotometric method was developed for the determination of ultra trace amounts of vanadium(V. The method is based on the catalytic effect of vanadium(V on the oxidation of malachite green oxalate (MG by bromate in acidic and micellar medium. The reaction was monitored spectrophotometrically by measuring the decrease in the absorbance of malachite green oxalate (MG at 625 nm with a fixed-time method. The decrease in the absorbance of MG is proportional to the concentration of vanadium(V in the range of 1-100 ng/mL with a fixed time of 0.5-2 min from the initiation of the reaction. The limit of detection is 0.71 ng/mL of vanadium(V. The relative standard deviation for the determination of 5, 30, 50 ng/mL of vanadium(V was2.5% 2.6%, 2.4% and respectively. The method was applied to the determination of vanadium(V in water samples.

  9. Mild and selective vanadium-catalyzed oxidation of benzylic, allylic, and propargylic alcohols using air

    Science.gov (United States)

    Hanson, Susan Kloek; Silks, Louis A; Wu, Ruilian

    2013-08-27

    The invention concerns processes for oxidizing an alcohol to produce a carbonyl compound. The processes comprise contacting the alcohol with (i) a gaseous mixture comprising oxygen; and (ii) an amine compound in the presence of a catalyst, having the formula: ##STR00001## where each of R.sup.1-R.sup.12 are independently H, alkyl, aryl, CF.sub.3, halogen, OR.sup.13, SO.sub.3R.sup.14, C(O)R.sup.15, CONR.sup.16R.sup.17 or CO.sub.2R.sup.18; each of R.sup.13-R.sup.18 is independently alkyl or aryl; and Z is alkl or aryl.

  10. Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane

    Energy Technology Data Exchange (ETDEWEB)

    McCormick, R.L. [Colorado School of Mines, Golden, CO (United States)

    1995-12-31

    The United States has vast natural gas reserves which could contribute significantly to our energy security if economical technologies for conversion to liquid fuels and chemicals were developed. Many of these reserves are small scale or in remote locations and of little value unless they can be transported to consumers. Transportation is economically performed via pipeline, but this route is usually unavailable in remote locations. Another option is to convert the methane in the gas to liquid hydrocarbons, such as methanol, which can easily and economically be transported by truck. Therefore, the conversion of methane to liquid hydrocarbons has the potential to decrease our dependence upon oil imports by opening new markets for natural gas and increasing its use in the transportation and chemical sectors of the economy. In this project, we are attempting to develop, and explore new catalysts capable of direct oxidation of methane to methanol. The specific objectives of this work are discussed.

  11. In situ vibrational spectroscopic investigation of C4 hydrocarbon selective oxidation over vanadium-phosphorus-oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhi -Yang [Iowa State Univ., Ames, IA (United States)

    1999-05-10

    n-Butane selective oxidation over the VPO catalyst to maleic anhydride is the first and only commercialized process of light alkane selective oxidation. The mechanism of this reaction is still not well known despite over twenty years of extensive studies, which can partially be attributed to the extreme difficulties to characterize catalytic reactions real-time under typical reaction conditions. In situ spectroscopic characterization techniques such as Infrared spectroscopy and laser Raman spectroscopy were used in the current mechanistic investigations of n-butane oxidation over VPO catalysts. To identify the reaction intermediates, oxidation of n-butane, 1,3-butadiene and related oxygenates on the VPO catalyst were monitored using FTIR spectroscopy under transient conditions. n-Butane was found to adsorb on the VPO catalyst to form olefinic species, which were further oxidized to unsaturated, noncyclic carbonyl species. The open chain dicarbonyl species then experienced cycloaddition to form maleic anhydride. VPO catalyst phase transformations were investigated using in situ laser Raman spectroscopy. This report contains Chapter 1: General introduction; Chapter 2: Literature review; and Chapter 5: Conclusion and recommendations.

  12. Vanadium based amorphous mixed oxides used as negative electrodes of lithium batteries; Oxydes mixtes amorphes a base de vanadium comme electrodes negatives de batteries au lithium

    Energy Technology Data Exchange (ETDEWEB)

    Guyomard, D.; Leroux, F.; Sigala, C.; Le Gal La Salle, A.; Piffard, Y. [Institut des Materiaux de Nantes, 44 (France). Laboratoire de Chimie des Solides

    1996-12-31

    This paper presents recent results concerning the chemical and electrochemical synthesis, the electrochemical properties and the characterization of two new families of amorphous oxides of formula Li{sub x}MVO{sub 4} (1oxides allows the low potential reversible insertion of lithium and can be used as negative electrodes in high performance lithium-ion batteries. (J.S.) 19 refs.

  13. Lithium Storage in Microstructures of Amorphous Mixed-Valence Vanadium Oxide as Anode Materials.

    Science.gov (United States)

    Zhao, Di; Zheng, Lirong; Xiao, Ying; Wang, Xia; Cao, Minhua

    2015-07-08

    Constructing three-dimensional (3 D) nanostructures with excellent structural stability is an important approach for realizing high-rate capability and a high capacity of the electrode materials in lithium-ion batteries (LIBs). Herein, we report the synthesis of hydrangea-like amorphous mixed-valence VOx microspheres (a-VOx MSs) through a facile solvothermal method followed by controlled calcination. The resultant hydrangea-like a-VOx MSs are composed of intercrossed nanosheets and, thus, construct a 3 D network structure. Upon evaluation as an anode material for LIBs, the a-VOx MSs show excellent lithium-storage performance in terms of high capacity, good rate capability, and long-term stability upon extended cycling. Specifically, they exhibit very stable cycling behavior with a highly reversible capacity of 1050 mA h g(-1) at a rate of 0.1 A g(-1) after 140 cycles. They also show excellent rate capability, with a capacity of 390 mA h g(-1) at a rate as high as 10 A g(-1) . Detailed investigations on the morphological and structural changes of the a-VOx MSs upon cycling demonstrated that the a-VOx MSs went through modification of the local VO coordinations accompanied with the formation of a higher oxidation state of V, but still with an amorphous state throughout the whole discharge/charge process. Moreover, the a-VOx MSs can buffer huge volumetric changes during the insertion/extraction process, and at the same time they remain intact even after 200 cycles of the charge/discharge process. Thus, these microspheres may be a promising anode material for LIBs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Ambient condition bias stress stability of vanadium (IV) oxide phthalocyanine based p-channel organic field-effect transistors

    Science.gov (United States)

    Obaidulla, Sk Md; Singh, Subhash; Mohapatra, Y. N.; Giri, P. K.

    2018-01-01

    High bias-stress stability and low threshold voltage (V th) shift under ambient conditions are highly desirable for practical applications of organic field-effect transistors (OFETs). We demonstrate here a 20-fold enhancement in the bias-stress stability for hexamethyledisilazane (HMDS) treated vanadium (IV) oxide phthalocyanine (VOPc) based OFETs as compared to the bare VOPc case under ambient conditions. VOPc based OFETs were fabricated on bare (non treated) SiO2 and a HMDS monolayer passivated SiO2 layer, with an operating voltage of 40 V. The devices with top contact gold (Au) electrodes exhibit excellent p-channel behavior with a moderate hole mobility for the HMDS-treated device. It is demonstrated that the time dependent ON-current decay and V th shift can be effectively controlled by using self-assembled monolayers of HMDS on the VOPc layer. For the HMDS-treated case, the bias stress stability study shows the stretched exponential decay of drain current by only ~15% during the long-term operation with constant bias voltage under ambient conditions, while it shows a large decay of  >70% for the nontreated devices operated for 1000 s. The corresponding characteric decay time constant (τ) is 104 s for the HMDS treated case, while that of the the non-treated SiO2 case is only ~480 s under ambient conditions. The inferior performance of the device with bare SiO2 is traced to the charge trapping at the voids in the inter-grain region of the films, while it is almost negligible for the HMDS-treated case, as confirmed from the AFM and XRD analyses. It is believed that HMDS treatment provides an excellent interface with a low density of traps and passivates the dangling bonds, which improve the charge transport characteristics. Also, the surface morphology of the VOPc film clearly influences the device performance. Thus, the HMDS treatment provides a very attractive approach for attaining long-term air stability and a low V th shift for the VOPc based OFET

  15. The critical role of phosphate in vanadium phosphate oxide for the catalytic activation and functionalization of n-butane to maleic anhydride.

    Science.gov (United States)

    Cheng, Mu-Jeng; Goddard, William A

    2013-03-27

    We used density functional theory to study the mechanism of n-butane oxidation to maleic anhydride on the vanadium phosphorus oxide (VPO) surface. We found that O(1)═P on the V(V)OPO4 surface is the active center for initiating the VPO chemistry through extraction of H from alkane C-H bonds. This contrasts sharply with previous suggestions that the active center is either the V-O bonds or else a chemisorbed O2 on the (V(IV)O)2P2O7 surface. The ability of O(1)═P to cleave alkane C-H bonds is due to its strong basicity coupled with large reduction potentials of nearby V(V) ions. We examined several pathways for the subsequent functionalization of n-butane to maleic anhydride and found that the overall barrier does not exceed 21.7 kcal/mol.

  16. XAS study of vanadium in fluid cracking catalysts

    Science.gov (United States)

    Woolery, G. L.; Chin, A. A.; Kirker, G. W.; Huss, A.

    1989-06-01

    X-ray absorption spectroscopy was used to investigate the oxidation state and local environment of vanadium in Fluid Catalytic Cracking (FCC) catalysts as a function of processing and deactivation conditions. Our results suggest that oxidation of vanadium to V+5 alone is not solely responsible for catalyst deactivation but that other factors such as vanadium location and mobility play a significant role in catalyst performance. Basic alkaline earth oxide passivators such as MgO were found to interact strongly with vanadium during the regeneration period leading to formation of a magnesium vanadate compound.

  17. Solid-state transformation of single precursor vanadium complex nanostructures to V₂O₅ and VO₂: catalytic activity of V₂O₅ for oxidative coupling of 2-naphthol.

    Science.gov (United States)

    Pradhan, Mukul; Roy, Anindita; Sinha, Arun Kumar; Sahoo, Ramkrishna; Deb, Dibakar; Pal, Tarasankar

    2015-01-28

    A vanadium complex, [(C5H5N)2V2O3·H2O], of different morphologies has been obtained via a modified hydrothermal procedure using pyridine and VOSO4 salt as the starting material. The evolved [(C5H5N)2V2O3·H2O] nanobelts are of 50-200 nm in width and of a length up to several millimeters. At higher temperatures (600 °C), the solid [(C5H5N)2V2O3·H2O] nanostructures are converted to vanadium pentoxide (V2O5) and vanadium dioxide (VO2) when heated in air and nitrogen atmosphere, respectively. During growth, the mechanism of the evolution of octahedra, truncated octahedra, and hollow truncated octahedra of [(C5H5N)2V2O3·H2O] are reported for the first time. These types of well-structured morphology are also isolated while V2O5 and VO2 are evolved. The as-grown belt-like and octahedral morphologies of [(C5H5N)2V2O3·H2O] are retained during the solid-state transformation, suggesting a route to evolve crystalline nanomaterials. Again, the morphological evolution of the [(C5H5N)2V2O3·H2O] nanostructures has been examined to be pyridine and precursor vanadyl sulfate (VS) concentration dependent. Thus, we are able to isolate truncated octahedra as an intermediate during the formation of [(C5H5N)2V2O3·H2O] nanobelts and nanoflowers with a high pyridine (Py) concentration. Interestingly, longer reaction times successively featured the transformation of truncated octahedra into nanobelts. Nanobelt evolution is not observed at low pyridine concentrations. However, the formation of octahedral morphology takes place at low pyridine concentration. All of the nanostructures were critically examined and characterized thoroughly by various physical techniques to ascertain their purity, structure and composition. An interesting, thermodynamically stable, single crystalline product from DMF soluble [(C5H5N)2V2O3·H2O] has been characterized, which indirectly supports the composition of [(C5H5N)2V2O3·H2O]. Selectively, vanadium pentoxide nanobelts have been found to be an

  18. Linking Precursor Alterations to Nanoscale Structure and Optical Transparency in Polymer Assisted Fast-Rate Dip-Coating of Vanadium Oxide Thin Films

    Science.gov (United States)

    Glynn, Colm; Creedon, Donal; Geaney, Hugh; Armstrong, Eileen; Collins, Timothy; Morris, Michael A.; Dwyer, Colm O.'

    2015-06-01

    Solution processed metal oxide thin films are important for modern optoelectronic devices ranging from thin film transistors to photovoltaics and for functional optical coatings. Solution processed techniques such as dip-coating, allow thin films to be rapidly deposited over a large range of surfaces including curved, flexible or plastic substrates without extensive processing of comparative vapour or physical deposition methods. To increase the effectiveness and versatility of dip-coated thin films, alterations to commonly used precursors can be made that facilitate controlled thin film deposition. The effects of polymer assisted deposition and changes in solvent-alkoxide dilution on the morphology, structure, optoelectronic properties and crystallinity of vanadium pentoxide thin films was studied using a dip-coating method using a substrate withdrawal speed within the fast-rate draining regime. The formation of sub-100 nm thin films could be achieved rapidly from dilute alkoxide based precursor solutions with high optical transmission in the visible, linked to the phase and film structure. The effects of the polymer addition was shown to change the crystallized vanadium pentoxide thin films from a granular surface structure to a polycrystalline structure composed of a high density of smaller in-plane grains, resulting in a uniform surface morphology with lower thickness and roughness.

  19. Linking Precursor Alterations to Nanoscale Structure and Optical Transparency in Polymer Assisted Fast-Rate Dip-Coating of Vanadium Oxide Thin Films

    Science.gov (United States)

    Glynn, Colm; Creedon, Donal; Geaney, Hugh; Armstrong, Eileen; Collins, Timothy; Morris, Michael A.; Dwyer, Colm O’

    2015-01-01

    Solution processed metal oxide thin films are important for modern optoelectronic devices ranging from thin film transistors to photovoltaics and for functional optical coatings. Solution processed techniques such as dip-coating, allow thin films to be rapidly deposited over a large range of surfaces including curved, flexible or plastic substrates without extensive processing of comparative vapour or physical deposition methods. To increase the effectiveness and versatility of dip-coated thin films, alterations to commonly used precursors can be made that facilitate controlled thin film deposition. The effects of polymer assisted deposition and changes in solvent-alkoxide dilution on the morphology, structure, optoelectronic properties and crystallinity of vanadium pentoxide thin films was studied using a dip-coating method using a substrate withdrawal speed within the fast-rate draining regime. The formation of sub-100 nm thin films could be achieved rapidly from dilute alkoxide based precursor solutions with high optical transmission in the visible, linked to the phase and film structure. The effects of the polymer addition was shown to change the crystallized vanadium pentoxide thin films from a granular surface structure to a polycrystalline structure composed of a high density of smaller in-plane grains, resulting in a uniform surface morphology with lower thickness and roughness. PMID:26123117

  20. Glucose-6-Phosphate Dehydrogenase in the Pentose Phosphate Pathway Is Localized in Vanadocytes of the Vanadium-Rich Ascidian, Ascidia sydneiensis samea

    OpenAIRE

    Taro, Uyama; Kazuhiro, YAMAMOTO; Kan, Kanamori; Hitoshi, Michibata; Department of Chemistry, Toyama University; Mukaishima Marine Biological Laboratory, Faculty of Science and Laboratory of Marine Molecular Biology, Graduate School of Science, Hiroshima University

    1998-01-01

    Ascidians are sessile marine animals known to accumulate high levels of vanadium selectively in vanadium-containing blood cells(vanadocytes). Almost all the vanadium accumulated in the vacuoles of vanadocytes is reduced to the +3 oxidation state via the +4 oxidation state, although vanadium is dissolved in the +5 oxidation state in sea water. Some of the reducing agents that participate in the reduction have been proposed. By chemical study, vanadium in the +5 oxidation state was reported to ...

  1. Vanadium Bioleaching Behavior by Acidithiobacillus ferrooxidans from a Vanadium-Bearing Shale

    Directory of Open Access Journals (Sweden)

    Dunpei Wei

    2018-01-01

    Full Text Available This study investigated bioleaching behavior of vanadium from a vanadium-bearing shale using Acidithiobacillus ferrooxidans (A. ferrooxidans. Results showed a maximum recovery of 62% vanadium in 1.2-day bioleaching, which was 22.45% higher than the controls. Then, the vanadium leaching efficiency decreased significantly, only 24% of that was obtained on the tenth day. The vanadium extraction in 1.2 days was mainly attributed to the dissolution of vanadium in free oxides of shale. Fe3+ produced by A. ferrooxidans promoted the dissolution process. X-ray diffraction (XRD patterns of the leached residues confirmed the generation of jarosite. SEM-EDS analysis of the residues indicated that jarosite adsorbed on the shale and inhibited the further dissolution of vanadium. The relevance of V, Fe, S, O was quite good in the energy disperse X-ray spectrometry (EDS element mapping of jarosite, and acid-washing of the jarosite resulted in 31.6% of the vanadium in the precipitates desorption, indicating that the decrease of vanadium leaching efficiency in bioleaching process was caused by both adsorption and co-precipitation with jarosite.

  2. Vanadium oxide based nanostructured materials for catalytic oxidative dehydrogenation of propane : effect of heterometallic centers on the catalyst performance.

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M. I.; Deb, S.; Aydemir, K.; Alwarthan, A. A.; Chattopadhyay, S.; Miller, J. T.; Marshall, C. L. (Chemical Sciences and Engineering Division); (Illinois Inst. of Tech.); (King Saud Univ.)

    2010-01-01

    Catalytic properties of a series of new class of catalysts materials-[Co{sub 3}(H{sub 2}O){sub 12}V{sub 18}O{sub 42} (XO{sub 4})].24H{sub 2}O (VNM-Co), [Fe{sub 3}(H{sub 2}O){sub 12}V{sub 18}O{sub 42}(XO{sub 4})].24H{sub 2}O (VNM-Fe) (X = V, S) and [H{sub 6}Mn{sub 3}(H{sub 2}O){sub 12}V{sub 18}O{sub 42}(VO{sub 4})].30H{sub 2}O for the oxidative dehydrogenation of propane is studied. The open-framework nanostructures in these novel materials consist of three-dimensional arrays of {l_brace}V{sub 18}O{sub 42}(XO{sub 4}){r_brace} (X = V, S) clusters interconnected by {l_brace}-O-M-O-{r_brace} (M = Mn, Fe, Co) linkers. The effect of change in the heterometallic center M (M = Mn, Co, Fe) of the linkers on the catalyst performance was studied. The catalyst material with Co in the linker showed the best performance in terms of propane conversion and selectivity at 350 C. The material containing Fe was most active but least selective and Mn containing catalyst was least active. The catalysts were characterized by Temperature Programmed Reduction (TPR), BET surface area measurement, Diffuse Reflectance Infrared Fourier Transform Spectroscopy, and X-ray Absorption Spectroscopy. TPR results show that all three catalysts are easily reducible and therefore are active at relatively low temperature. In situ X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure spectroscopy (EXAFS) studies revealed that the oxidation state of Co(II) remained unchanged up to 425 C (even after pretreatment). The reduction of Co(II) into metallic form starts at 425 C and this process is completed at 600 C.

  3. Low visibility operations/surface movement guidance and control system (LVO/SMGCS) chart usability : an examination of flightcrew position awareness in homogeneous 300 ft/75 m RVR conditions

    Science.gov (United States)

    2014-09-01

    Two studies were conducted to identify best practices for the design of Low Visibility Operations/Surface Movement Guidance and Control System (LVO/SMGCS) paper charts and flightcrew use of them in extremely low visibility surface conditions. In the ...

  4. Recovery of Vanadium from a High Ca/V Ratio Vanadium Slag Using Sodium Roasting and Ammonia Leaching

    Science.gov (United States)

    Xu, Song; Long, Mujun; Chen, Dengfu; Fan, Helin; Chen, Yuting; Sun, Xue

    In order to seek an effective extraction process for vanadium, the recovery of vanadium from a high Ca/V ratio vanadium slag was studied by sodium roasting and ammonia leaching. In the present paper, the oxidation and leaching process of vanadium slag was investigated by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDS) techniques. The effects of ammonium carbonate concentration, leaching temperature and leaching time on the leaching ratio of vanadium were discussed. As indicated in the experimental result, the optimal (NH4)2CO3 concentration was 120g/L, leaching temperature was 60°C and leaching time was 20 min. Approximately 92% of the vanadium was recovered under the optimal conditions. Furthermore, by means of X-ray diffraction analysis, the phase transformations of the vanadium slag during roasting and leaching processes were analyzed and discussed.

  5. A study of tin dioxide and antimony tetroxide supported vanadium oxide catalysts by solid-state 51V and 1H NMR techniques.

    Science.gov (United States)

    Reddy, B M; Mastikhin, V M

    1992-12-01

    A series of vanadia catalysts with various V2O5 loadings supported on SnO2 and alpha-Sb2O4 are investigated by the application of X-ray diffraction and solid-state 51V and 1H NMR techniques. XRD results show no evidence for the formation of a crystalline vanadia phase on both supports. However, the 51V NMR spectra of the catalysts reveal the existence of two types of vanadia species on the surface of the support: one due to a dispersed vanadia phase at lower vanadia loadings and the other due to a crystalline vanadia phase at higher vanadium content. The quantity of the dispersed vanadia phase, however, depends on the nature of the support material. The 1H NMR results provide evidence for the existence or non-existence of a metal oxide support interaction through the support surface hydroxyl groups.

  6. Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}): Peroxovanadate sol gel synthesis and structural study

    Energy Technology Data Exchange (ETDEWEB)

    Langie da Silva, Douglas, E-mail: douglas.langie@ufpel.edu.br [Departamento de Física, Universidade Federal de Pelotas, Caixa Postal 354, Pelotas 96010-900 (Brazil); Moreira, Eduardo Ceretta [Laboratório de Espectroscopia, Universidade Federal do Pampa, Campus Bagé, Bagé 96400-970 (Brazil); Dias, Fábio Teixeira; Neves Vieira, Valdemar das [Departamento de Física, Universidade Federal de Pelotas, Caixa Postal 354, Pelotas 96010-900 (Brazil); Brandt, Iuri Stefani; Cas Viegas, Alexandre da; Pasa, André Avelino [Laboratório de Filmes Finos e Superfícies, Universidade Federal de Santa Catarina, Caixa Postal 476, Florianópolis 88.040-900 (Brazil)

    2015-01-15

    Nanostructured cobalt vanadium oxide (V{sub 2}O{sub 5}) xerogels spread onto crystalline Si substrates were synthesized via peroxovanadate sol gel route. The resulting products were characterized by distinct experimental techniques. The surface morphology and the nanostructure of xerogels correlate with Co concentration. The decrease of the structural coherence length is followed by the formation of a loose network of nanopores when the concentration of intercalated species was greater than 4 at% of Co. The efficiency of the synthesis route also drops with the increase of Co concentration. The interaction between the Co(OH{sub 2}){sub 6}{sup 2+} cations and the (H{sub 2}V{sub 10}O{sub 28}){sup 4−} anions during the synthesis was suggested as a possible explanation for the incomplete condensation of the V{sub 2}O{sub 5} gel. Finally the experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5}. In this scenario two possible preferential occupation sites for the metallic atoms in the framework of the xerogel were proposed. - Graphical abstract: Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V{sub 2}O{sub 5}) nanoribbons synthesized by peroxovanadate sol gel route. - Highlights: • Nanostructured cobalt V{sub 2}O{sub 5} gel spread onto c{sub S}i were synthesized via peroxovanadate sol gel route. • The micro and nanostructure correlates with the cobalt content. • The efficiency of the synthesis route shows to be also dependent of Co content. • The experimental results points for the intercalation of Co between the bilayers of the V{sub 2}O{sub 5} xerogel.

  7. Vanadium recycling in the United States in 2004

    Science.gov (United States)

    Goonan, Thomas G.

    2011-01-01

    As one of a series of reports that describe the recycling of metal commodities in the United States, this report discusses the flow of vanadium in the U.S. economy in 2004. This report includes a description of vanadium supply and demand in the United States and illustrates the extent of vanadium recycling and recycling trends. In 2004, apparent vanadium consumption, by end use, in the United States was 3,820 metric tons (t) in steelmaking and 232 t in manufacturing, of which 17 t was for the production of superalloys and 215 t was for the production of other alloys, cast iron, catalysts, and chemicals. Vanadium use in steel is almost entirely dissipative because recovery of vanadium from steel scrap is chemically impeded under the oxidizing conditions in steelmaking furnaces. The greatest amount of vanadium recycling is in the superalloy, other-alloy, and catalyst sectors of the vanadium market. Vanadium-bearing catalysts are associated with hydrocarbon recovery and refining in the oil industry. In 2004, 2,850 t of vanadium contained in alloy scrap and spent catalysts was recycled, which amounted to about 44 percent of U.S. domestic production. About 94 percent of vanadium use in the United States was dissipative (3,820 t in steel/4,050 t in steel+fabricated products).

  8. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications.

    Science.gov (United States)

    Skuza, J R; Scott, D W; Mundle, R M; Pradhan, A K

    2016-02-17

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5-10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT.

  9. Vanadium Compounds as PTP Inhibitors

    Directory of Open Access Journals (Sweden)

    Elsa Irving

    2017-12-01

    Full Text Available Phosphotyrosine signaling is regulated by the opposing actions of protein tyrosine kinases (PTKs and protein tyrosine phosphatases (PTPs. Here we discuss the potential of vanadium derivatives as PTP enzyme inhibitors and metallotherapeutics. We describe how vanadate in the V oxidized state is thought to inhibit PTPs, thus acting as a pan-inhibitor of this enzyme superfamily. We discuss recent developments in the biological and biochemical actions of more complex vanadium derivatives, including decavanadate and in particular the growing number of oxidovanadium compounds with organic ligands. Pre-clinical studies involving these compounds are discussed in the anti-diabetic and anti-cancer contexts. Although in many cases PTP inhibition has been implicated, it is also clear that many such compounds have further biochemical effects in cells. There also remain concerns surrounding off-target toxicities and long-term use of vanadium compounds in vivo in humans, hindering their progress through clinical trials. Despite these current misgivings, interest in these chemicals continues and many believe they could still have therapeutic potential. If so, we argue that this field would benefit from greater focus on improving the delivery and tissue targeting of vanadium compounds in order to minimize off-target toxicities. This may then harness their full therapeutic potential.

  10. Analyzing optical properties of thin vanadium oxide films through semiconductor-to-metal phase transition using spectroscopic ellipsometry

    Science.gov (United States)

    Sun, Jianing; Pribil, Greg K.

    2017-11-01

    We investigated the optical behaviors of vanadium dioxide (VO2) films through the semiconductor-to-metal (STM) phase transition using spectroscopic ellipsometry. Correlations between film thickness and refractive index were observed resulting from the absorbing nature of these films. Simultaneously analyzing data at multiple temperatures using Kramers-Kronig consistent oscillator models help identify film thickness. Nontrivial variations in resulting optical constants were observed through STM transition. As temperature increases, a clear increase is observed in near infrared absorption due to Drude losses that accompany the transition from semiconducting to metallic phases. Thin films grown on silicon and sapphire substrate present different optical properties and thermal hysteresis due to lattice stress and compositional differences.

  11. Effect of vanadium substitution on structural and electrical properties of sol-gel grown nanostructured zinc oxide

    Science.gov (United States)

    Boricha, Hetal; Rajyaguru, Bhargav; Gadani, Keval; Rathod, K. N.; Shrimali, V. G.; Udeshi, Bhagyashree; Keshvani, M. J.; Joshi, A. D.; Pandya, D. D.; Solanki, P. S.; Shah, N. A.

    2017-05-01

    In the present communication, we report the results on the structural and electrical studies on nanostructured pure (ZnO) and Vanadium (V) doped Zn0.95V0.05O samples synthesized using low cost Sol-Gel technique. To understand the structural properties and their dependence on V substitution, X-Ray diffraction (XRD) measurement was carried out for both the samples understudy. XRD results reveal the single phasic wurtzite nature of both the samples showing hexagonal unit cell structure. A minor phase of ZnV2O6 is observed in V doped ZnO sample. Improved dielectric permittivity, enhanced ac conductivity (σac) and suppression in impedance have been discussed on the basis of structural modifications by the substitution of V in ZnO, enhanced charge carrier concentration, charge carrier polarization and correlated barrier hopping due to the localized state.

  12. Vanadium Pentoxide Nanobelt-Reduced Graphene Oxide Nanosheet Composites as High-Performance Pseudocapacitive Electrodes: ac Impedance Spectroscopy Data Modeling and Theoretical Calculations

    Directory of Open Access Journals (Sweden)

    Sanju Gupta

    2016-07-01

    Full Text Available Graphene nanosheets and graphene nanoribbons, G combined with vanadium pentoxide (VO nanobelts (VNBs and VNBs forming GVNB composites with varying compositions were synthesized via a one-step low temperature facile hydrothermal decomposition method as high-performance electrochemical pseudocapacitive electrodes. VNBs from vanadium pentoxides (VO are formed in the presence of graphene oxide (GO, a mild oxidant, which transforms into reduced GO (rGOHT, assisting in enhancing the electronic conductivity coupled with the mechanical robustness of VNBs. From electron microscopy, surface sensitive spectroscopy and other complementary structural characterization, hydrothermally-produced rGO nanosheets/nanoribbons are decorated with and inserted within the VNBs’ layered crystal structure, which further confirmed the enhanced electronic conductivity of VNBs. Following the electrochemical properties of GVNBs being investigated, the specific capacitance Csp is determined from cyclic voltammetry (CV with a varying scan rate and galvanostatic charging-discharging (V–t profiles with varying current density. The rGO-rich composite V1G3 (i.e., VO/GO = 1:3 showed superior specific capacitance followed by VO-rich composite V3G1 (VO/GO = 3:1, as compared to V1G1 (VO/GO = 1:1 composite, besides the constituents, i.e., rGO, rGOHT and VNBs. Composites V1G3 and V3G1 also showed excellent cyclic stability and a capacitance retention of >80% after 500 cycles at the highest specific current density. Furthermore, by performing extensive simulations and modeling of electrochemical impedance spectroscopy data, we determined various circuit parameters, including charge transfer and solution resistance, double layer and low frequency capacitance, Warburg impedance and the constant phase element. The detailed analyses provided greater insights into physical-chemical processes occurring at the electrode-electrolyte interface and highlighted the comparative performance of

  13. Vanadium phosphates on mesoporous supports: model catalysts for solid-state NMR studies of the selective oxidation of n-butane.

    Science.gov (United States)

    Frey, Jörg; Sang Ooi, Yean; Thomas, Bejoy; Reddy Marthala, V R; Bressel, Arne; Schölkopf, Thomas; Schleid, Thomas; Hunger, Michael

    2009-04-01

    SBA-15 was utilized as mesoporous support for the dispersion of vanadium phosphate (VPO) compounds. Loading of SBA-15 with VPO compounds was found to be accompanied by decreasing (29)Si MAS NMR signals of Q(2) (Si(2Si,2OH)) and Q(3) (Si(3Si,1OH)) silicon species, which indicates coverage of the mesoporous support by the guest compounds. The (51)V MAS NNR spectra of the activated VPO/SBA-15 catalysts consist of patterns typical for the alpha(II)- and beta-phases of vanadyl orthophosphate. In the (31)P MAS NMR spectra of the activated VPO/SBA-15 catalysts, signals of beta-, delta-, and alpha(II)-VOPO(4) phases could be identified. Upon conversion of n-butane-(13)C(4), a strong decrease of the (31)P MAS NMR signals characteristic for the delta-VOPO(4) phase occurred, while by (13)C MAS NMR spectroscopy the formation of maleic anhydride, carbon monoxide, and carbon dioxide was observed. This finding supports the active role of the delta-VOPO(4) phase in the selective oxidation of n-butane on VPO/SBA-15 catalysts.

  14. Quasi-one-dimensional nanostructured cobalt (Co) intercalated vanadium oxide (V2O5): Peroxovanadate sol gel synthesis and structural study

    Science.gov (United States)

    da Silva, Douglas Langie; Moreira, Eduardo Ceretta; Dias, Fábio Teixeira; Neves Vieira, Valdemar das; Brandt, Iuri Stefani; Cas Viegas, Alexandre da; Pasa, André Avelino

    2015-01-01

    Nanostructured cobalt vanadium oxide (V2O5) xerogels spread onto crystalline Si substrates were synthesized via peroxovanadate sol gel route. The resulting products were characterized by distinct experimental techniques. The surface morphology and the nanostructure of xerogels correlate with Co concentration. The decrease of the structural coherence length is followed by the formation of a loose network of nanopores when the concentration of intercalated species was greater than 4 at% of Co. The efficiency of the synthesis route also drops with the increase of Co concentration. The interaction between the Co(OH2)62+ cations and the (H2V10O28)4- anions during the synthesis was suggested as a possible explanation for the incomplete condensation of the V2O5 gel. Finally the experimental results points for the intercalation of Co between the bilayers of the V2O5. In this scenario two possible preferential occupation sites for the metallic atoms in the framework of the xerogel were proposed.

  15. Strengthening of Ceramic-based Artificial Nacre via Synergistic Interactions of 1D Vanadium Pentoxide and 2D Graphene Oxide Building Blocks

    Science.gov (United States)

    Knöller, Andrea; Lampa, Christian P.; Cube, Felix Von; Zeng, Tingying Helen; Bell, David C.; Dresselhaus, Mildred S.; Burghard, Zaklina; Bill, Joachim

    2017-01-01

    Nature has evolved hierarchical structures of hybrid materials with excellent mechanical properties. Inspired by nacre’s architecture, a ternary nanostructured composite has been developed, wherein stacked lamellas of 1D vanadium pentoxide nanofibres, intercalated with water molecules, are complemented by 2D graphene oxide (GO) nanosheets. The components self-assemble at low temperature into hierarchically arranged, highly flexible ceramic-based papers. The papers’ mechanical properties are found to be strongly influenced by the amount of the integrated GO phase. Nanoindentation tests reveal an out-of-plane decrease in Young’s modulus with increasing GO content. Furthermore, nanotensile tests reveal that the ceramic-based papers with 0.5 wt% GO show superior in-plane mechanical performance, compared to papers with higher GO contents as well as to pristine V2O5 and GO papers. Remarkably, the performance is preserved even after stretching the composite material for 100 nanotensile test cycles. The good mechanical stability and unique combination of stiffness and flexibility enable this material to memorize its micro- and macroscopic shape after repeated mechanical deformations. These findings provide useful guidelines for the development of bioinspired, multifunctional systems whose hierarchical structure imparts tailored mechanical properties and cycling stability, which is essential for applications such as actuators or flexible electrodes for advanced energy storage.

  16. Vanadium-Catalyzed Oxidative C(CO)-C(CO) Bond Cleavage for C-N Bond Formation: One-Pot Domino Transformation of 1,2-Diketones and Amidines into Imides and Amides.

    Science.gov (United States)

    Digwal, Chander Singh; Yadav, Upasana; Ramya, P V Sri; Sana, Sravani; Swain, Baijayantimala; Kamal, Ahmed

    2017-07-21

    A novel vanadium-catalyzed one-pot domino reaction of 1,2-diketones with amidines has been identified that enables their transformation into imides and amides. The reaction proceeds by dual acylation of amidines via oxidative C(CO)-C(CO) bond cleavage of 1,2-diketones to afford N,N'-diaroyl-N-arylbenzamidine intermediates. In the reaction, these intermediates are easily hydrolyzed into imides and amides through vanadium catalysis. This method provides a practical, simple, and mild synthetic approach to access a variety of imides as well as amides in high yields. Moreover, one-step construction of imide and amide bonds with a long-chain alkyl group is an attractive feature of this protocol.

  17. Vanadium pentoxide nanoparticles mimic vanadium haloperoxidases and thwart biofilm formation

    Science.gov (United States)

    Natalio, Filipe; André, Rute; Hartog, Aloysius F.; Stoll, Brigitte; Jochum, Klaus Peter; Wever, Ron; Tremel, Wolfgang

    2012-08-01

    Marine biofouling--the colonization of small marine microorganisms on surfaces that are directly exposed to seawater, such as ships' hulls--is an expensive problem that is currently without an environmentally compatible solution. Biofouling leads to increased hydrodynamic drag, which, in turn, causes increased fuel consumption and greenhouse gas emissions. Tributyltin-free antifouling coatings and paints based on metal complexes or biocides have been shown to efficiently prevent marine biofouling. However, these materials can damage the environment through metal leaching (for example, of copper and zinc) and bacteria resistance. Here, we show that vanadium pentoxide nanowires act like naturally occurring vanadium haloperoxidases to prevent marine biofouling. In the presence of bromide ions and hydrogen peroxide, the nanowires catalyse the oxidation of bromide ions to hypobromous acid (HOBr). Singlet molecular oxygen (1O2) is formed and this exerts strong antibacterial activity, which prevents marine biofouling without being toxic to marine biota. Vanadium pentoxide nanowires have the potential to be an alternative approach to conventional anti-biofouling agents.

  18. Dependence of Vanadium Recovery

    African Journals Online (AJOL)

    a large-scale vanadium processing or separation processes where vanadium is a contaminant. However, the ... in a separating funnel, swirled manually and later on a mechanical shaker operated at 120 rpm for 2 minutes ..... (40% v/v) TBP and the relevant scheme for extraction would be according to Equation 7. VOCl + n ...

  19. Oxidative dehydrogenation of n-butane over magnesium vanadate nano-catalysts supported on magnesia-zirconia: effect of vanadium content.

    Science.gov (United States)

    Lee, Jong Kwon; Hong, Ung Gi; Yoo, Yeonshick; Cho, Young-Jin; Lee, Jinsuk; Chang, Hosik; Song, In Kyu

    2013-12-01

    Magnesia-zirconia (MgO-ZrO2) support was prepared by a sol-gel method, and magnesium vanadate nano-catalysts supported on magnesia-zirconia (X-Mg3(VO4)2/MgO-ZrO2) were then prepared by a wet impregnation method with a variation of vanadium content (X = 6.6, 9.9, 12.8, 15.2, and 19.1 wt%). X-Mg3(VO4)2/MgO-ZrO2 nano-catalysts were applied to the oxidative dehydrogenation of n-butane to n-butene and 1,3-butadiene. The formation of X-Mg3(VO4)2/MgO-ZrO2 nano-catalysts was well confirmed by XRD, XPS, and ICP-AES analyses. 15.2-Mg3(VO4)2/MgO-ZrO2 and 19.1-Mg3(VO4)2/MgO-ZrO2 catalysts experienced a catalyst deactivation, while the other Mg3(VO4)2/MgO-ZrO2 catalysts showed a stable catalytic performance during the whole reaction time. The effect of oxygen property of X-Mg3(VO4)2/MgO-ZrO2 nano-catalysts on the catalytic performance in the oxidative dehydrogenation of n-butane was investigated. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic performance, while oxygen mobility of the catalyst played an important role in the catalyst stability. Among the catalysts tested, 12.8-Mg3(VO4)2/MgO-ZrO2 catalyst showed the best catalytic performance in terms of yield for TDP (total dehydrogenation products).

  20. A novel process for the recovery of iron, titanium, and vanadium from vanadium-bearing titanomagnetite: sodium modification-direct reduction coupled process

    Science.gov (United States)

    Zhang, Yi-min; Yi, Ling-yun; Wang, Li-na; Chen, De-sheng; Wang, Wei-jing; Liu, Ya-hui; Zhao, Hong-xin; Qi, Tao

    2017-05-01

    A sodium modification-direct reduction coupled process was proposed for the simultaneous extraction of V and Fe from vanadium- bearing titanomagnetite. The sodium oxidation of vanadium oxides to water-soluble sodium vanadate and the transformation of iron oxides to metallic iron were accomplished in a single-step high-temperature process. The increase in roasting temperature favors the reduction of iron oxides but disfavors the oxidation of vanadium oxides. The recoveries of vanadium, iron, and titanium reached 84.52%, 89.37%, and 95.59%, respectively. Moreover, the acid decomposition efficiency of titanium slag reached 96.45%. Compared with traditional processes, the novel process provides several advantages, including a shorter flow, a lower energy consumption, and a higher utilization efficiency of vanadium-bearing titanomagnetite resources.

  1. Structure and function of vanadium haloperoxidases

    NARCIS (Netherlands)

    Wever, R.; Michibata, H.

    2012-01-01

    Vanadium haloperoxidases contain the bare metal oxide vanadate as a prosthetic group and differ strongly from the heme peroxidases in substrate specificity and molecular properties. The substrates of these enzymes are limited to halides and sulfides, which in the presence of hydrogen peroxide are

  2. Role of vanadium in Keggin heteropoly molybdate supported on ...

    Indian Academy of Sciences (India)

    ated for oxidation of 1,2-benzenedimethanol using H2O2 and O2 as oxidants. .... C on oil bath. In the case of O2 as oxidant, reaction was conducted under O2 atmosphere. Progress of the reaction was monitored by using thin-layer chro- ... The role of vanadium in heteropoly molybdate catalysts for oxidation reactions. 469.

  3. Kinetics of Vanadium Extraction from Hot Metal by Basic Slag

    Science.gov (United States)

    Zhang, Tao; Xie, Bing; Liu, Xuan; Diao, Jiang; Zhang, Zhen; Li, Hong-Yi

    Extracting vanadium from vanadium containing hot metal by LD process has been proven an effective solution for the utilization of vanadium-titanium magnetite ore, but the systematic analyses of vanadium extraction rate and mechanism by basic slag are seldom reported. In this study, mathematical model of vanadium transfer from metal to slag was formulated and the rates of vanadium extraction of hot metal with basic slag were investigated. The results indicated that the apparent vanadium extraction rate constant, k p , were in the range of 1.33˜9.07×10-4g/(cm3·s). And the rate constant was increased with the increase of final slag basicity, reaction temperature and stirring gas flow. The apparent of mass transfer parameter decreases significantly from 0.13 cm3/ s to 0 cm3/ s in 20min, and the data changed as negative due to the decrease of slag oxidation and recovery of vanadium from slag to metal.

  4. On the structural and electronic properties of hexanuclear vanadium oxide clusters V6On(-/0) (n=12-15): is V6O12 cluster planar or cage-like?

    Science.gov (United States)

    Wang, Ling-Fei; Xie, Lu; Fang, Hong-Ling; Li, Yun-Fei; Zhang, Xiao-Bin; Wang, Bin; Zhang, Yong-Fan; Huang, Xin

    2014-10-15

    Density functional theory (DFT) calculations are carried out to investigate the structural and electronic properties of a series of hexanuclear vanadium oxide clusters V6On(-/0) (n=12-15). Generalized Koopmans' theorem is applied to predict the vertical detachment energies (VDEs) and simulate the photoelectron spectra (PES) for V6On(-) (n=12-15) clusters. Extensive DFT calculations are performed in search of the lowest-energy structures for both the anions and neutrals. All of these clusters appear to prefer the polyhedral cage structures, in contrast to the planar star-like structures observed in prior model surface studies for the V6O12 cluster. Molecular orbitals are performed to analyze the chemical bonding in the hexanuclear vanadium oxide clusters and provide insights into the sequential oxidation of V6On(-) (n=12-15) clusters. The V6On(-) (n=12-15) clusters possess well-defined V(5+) and V(3+) sites, and may serve as molecular models for surface defects. Electron spin density analyses show that the unpaired electrons in V6On(-) (n=12-14) clusters are primarily localized on the V(3+) sites rather than on the V(5+) sites. The difference gas phase versus model surface structures of V6O12 hints the critical roles of cluster-substrate interactions in stabilizing the planar V6O12 cluster on model surfaces. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Vanadium Recovery from Oil Fly Ash by Carbon Removal and Roast-Leach Process

    Science.gov (United States)

    Jung, Myungwon; Mishra, Brajendra

    2017-11-01

    This research mainly focuses on the recovery of vanadium from oil fly ash by carbon removal and the roast-leach process. The oil fly ash contained about 85% unburned carbon and 2.2% vanadium by weight. A vanadium-enriched product was obtained after carbon removal, and the vanadium content of this product was 19% by weight. Next, the vanadium-enriched product was roasted with sodium carbonate to convert vanadium oxides to water-soluble sodium metavanadate. The roasted sample was leached with water at 60°C, and the extraction percentage of vanadium was about 92% by weight. Several analytical techniques, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), x-ray fluorescence (XRF), and thermogravimetric and differential thermal analysis (TG-DTA), were utilized for sample analyses. Thermodynamic modeling was also conducted with HSC chemistry software to explain the experimental results.

  6. Vanadium Recovery from Oil Fly Ash by Carbon Removal and Roast-Leach Process

    Science.gov (United States)

    Jung, Myungwon; Mishra, Brajendra

    2018-02-01

    This research mainly focuses on the recovery of vanadium from oil fly ash by carbon removal and the roast-leach process. The oil fly ash contained about 85% unburned carbon and 2.2% vanadium by weight. A vanadium-enriched product was obtained after carbon removal, and the vanadium content of this product was 19% by weight. Next, the vanadium-enriched product was roasted with sodium carbonate to convert vanadium oxides to water-soluble sodium metavanadate. The roasted sample was leached with water at 60°C, and the extraction percentage of vanadium was about 92% by weight. Several analytical techniques, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), x-ray fluorescence (XRF), and thermogravimetric and differential thermal analysis (TG-DTA), were utilized for sample analyses. Thermodynamic modeling was also conducted with HSC chemistry software to explain the experimental results.

  7. Pathway and Surface Mechanism Studies of 1,3-butadiene Selective Oxidation Over Vanadium-Molybdenum-Oxygen Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, William David [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m2/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO3/(MoO3 + V2O5). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V+4 and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to maleic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The addition of water to the reaction stream substantially increased catalyst activity and improved selectivity to crotonaldehyde and furan at specific reaction temperatures. At higher water addition concentrations, furan selectivity increased from 12% to over 25%. The catalytic effects of water addition were related to competitive adsorption with various V2O5-based surface sites, including the vanadyl V=O, corner sharing V-O-V and edge sharing V-O oxygen. Higher levels of water addition were proposed to impose acidic character by dissociative adsorption. In addition, a novel combinatorial synthesis technique for VMoO was used to investigate the phase transitions of V2O5, solid solutions of Mo in V2O5, V9Mo6O40, and other reduced VMoO compounds, characterized by laser Raman spectroscopy. The natural composition gradient imposed by the sputter deposition apparatus was used to create VMoO arrays containing 225 samples ranging from 7.0-42 mol% MoO3/(V2O5 + MoO3), determined by EDS analysis.

  8. Catalytic determination of vanadium in water

    Science.gov (United States)

    Fishman, M. J.; Skougstad, M.W.

    1964-01-01

    A rapid, accurate, and sensitive spectrophotometric method for the quantitative determination of trace amounts of vanadium in water is based on the catalytic effect of vanadium on the rate of oxidation of gallic acid by persulfate in acid solution. Under given conditions of concentrations of reactants, temperature, and reaction time, the extent of oxidation of gallic acid is proportional to the concentration of vanadium present. Vanadium is determined by measuring the absorbance of the sample at 415 m?? and comparison with standard solutions treated in an identical manner. Concentrations in the range of from 0.1 to 8.0 ??g. per liter may be determined with a standard deviation of 0.2 or less. By reducing the reaction time, the method may be extended to cover the range from 1 to 100 ??g. with a standard deviation of 0.8 or less. Several substances interfere, including chloride above 100 p.p.m., and bromide and iodide in much lower concentrations. Interference from the halides is eliminated or minimized by the addition of mercuric nitrate solution. Most other substances do not interfere at the concentration levels at which they commonly occur in natural waters.

  9. Synthesis and characterization of sodium vanadium oxide gels: the effects of water (n) and sodium (x) content on the electrochemistry of Na(x)V2O5·nH2O.

    Science.gov (United States)

    Lee, Chia-Ying; Marschilok, Amy C; Subramanian, Aditya; Takeuchi, Kenneth J; Takeuchi, Esther S

    2011-10-28

    Sodium vanadium oxide gels, Na(x)V(2)O(5)·nH(2)O, of varying sodium content (0.12 n > 0.01) and interlayer spacing were found to be inversely proportional to the sodium level (x), thus control of sodium (x) content provided a direct, chimie douce approach for control of hydration level (n) and interlayer spacing, without the need for high temperature treatment to affect dehydration. Notably, the use of high temperatures to modify hydration levels can result in crystallization and collapse of the interlayer structure, highlighting the distinct advantage of our novel chimie douce synthesis strategy. Subsequent to synthesis and characterization, results from an electrochemical study of a series of Na(x)V(2)O(5)·nH(2)O samples highlight the significant impact of interlayer water on delivered capacity of the layered materials. Specifically, the sodium vanadium oxide gels with higher sodium content and lower water content provided higher capacities in lithium based cells, where capacity delivered to 2.0 V under C/20 discharge ranged from 170 mAh/g for Na(0.12)V(2)O(5)·0.23H(2)O to 300 mAh/g for Na(0.32)V(2)O(5)·0.01H(2)O. The capacity differences were maintained as the cells were cycled. This journal is © the Owner Societies 2011

  10. Glucose-6-Phosphate Dehydrogenase in the Pentose Phosphate Pathway Is Localized in Vanadocytes of the Vanadium-Rich Ascidian, Ascidia sydneiensis samea.

    Science.gov (United States)

    Uyama, T; Yamamoto, K; Kanamori, K; Michibata, H

    1998-08-01

    Ascidians are sessile marine animals known to accumulate high levels of vanadium selectively in vanadium-containing blood cells (vanadocytes). Almost all the vanadium accumulated in the vacuoles of vanadocytes is reduced to the +3 oxidation state via the +4 oxidation state, although vanadium is dissolved in the +5 oxidation state in sea water. Some of the reducing agents that participate in the reduction have been proposed. By chemical study, vanadium in the +5 oxidation state was reported to be reduced to the +4 oxidation state in the presence of NADPH. The present study revealed the existence of glucose-6-phosphodehydrogenase (G6PDH), the first enzyme to produce NADPH in the pentose phosphate pathway, in vanadocytes of a vanadium-rich ascidian. The results suggested that G6PDH conjugates the reduction of vanadium from the +5 through to the +4 oxidation state in vanadocytes of ascidians.

  11. A coordination chemistry study of hydrated and solvated cationic vanadium ions in oxidation states +III, +IV, and +V in solution and solid state.

    Science.gov (United States)

    Krakowiak, Joanna; Lundberg, Daniel; Persson, Ingmar

    2012-09-17

    The coordination chemistry of hydrated and solvated vanadium(III), oxovanadium(IV), and dioxovanadium(V) ions in the oxygen-donor solvents water, dimethyl sulfoxide (DMSO), and N,N'-dimethylpropyleneurea (DMPU) has been studied in solution by extended X-ray absorption fine structure (EXAFS) and large-angle X-ray scattering (LAXS) and in the solid state by single-crystal X-ray diffraction and EXAFS. The hydrated vanadium(III) ion has a regular octahedral configuration with a mean V-O bond distance of 1.99 Å. In the hydrated and DMSO-solvated oxovanadium(IV) ions, vanadium binds strongly to an oxo group at ca. 1.6 Å. The solvent molecule trans to the oxo group is very weakly bound, at ca. 2.2 Å, while the remaining four solvent molecules, with a mean V-O bond distance of 2.0 Å, form a plane slightly below the vanadium atom; the mean O═V-O(perp) bond angle is ca. 98°. In the DMPU-solvated oxovanadium(IV) ion, the space-demanding properties of the DMPU molecule leave no solvent molecule in the trans position to the oxo group, which reduces the coordination number to 5. The O═V-O bond angle is consequently much larger, 107°, and the mean V═O and V-O bond distances decrease to 1.58 and 1.97 Å, respectively. The hydrated and DMSO-solvated dioxovanadium(V) ions display a very distorted octahedral configuration with the oxo groups in the cis position with a mean V═O bond distance of 1.6 Å and a O═V═O bond angle of ca. 105°. The solvent molecules trans to the oxo groups are weakly bound, at ca. 2.2 Å, while the remaining two have bond distances of 2.02 Å. The experimental studies of the coordination chemistry of hydrated and solvated vanadium(III,IV,V) ions are complemented by summarizing previously reported crystal structures to yield a comprehensive description of the coordination chemistry of vanadium with oxygen-donor ligands.

  12. Controlled synthesis and electrochemical properties of vanadium ...

    Indian Academy of Sciences (India)

    Vanadium oxides (V3O7.H2O and VO2) with different morphologies have been selectively synthesized by a facile hydrothermal approach using glucose as the reducing and structure-directing reagent. The as-obtained V3O7.H2O nanobelts have a length up to several tens of micrometers, width of about 60–150 nm and ...

  13. Reductive mineralization of cellulose with vanadium, iron and tungsten chlorides and access to MxOymetal oxides and MxOy/C metal oxide/carbon composites.

    Science.gov (United States)

    Henry, Aurélien; Hesemann, Peter; Alauzun, Johan G; Boury, Bruno

    2017-10-15

    M x O y and M x O y /C composites (M=V, Fe and W) were obtained by mineralization of cellulose with several metal chlorides. Cellulose was used both as a templating agent and as an oxygen and a carbon source. Soluble chloride molecules (VOCl 3 and WCl 6 ) and a poorly soluble ionic chloride compound (FeCl 3 ) were chosen as metal oxide precursors. In a first time, primary metal oxide/cellulose composites were obtained via a thermal treatment by reacting urea impregnated filter paper with the corresponding metal chlorides in an autoclave at 150°C after 3days. After either pyrolysis or calcination steps of these intermediate materials, interesting metal oxides with various morphologies were obtained (V 2 O 5, V 2 O 3 , Fe 3 O 4 , WO 3, H 0.23 WO 3 ), composites (V 2 O 3 /C) as well as carbides (hexagonal W 2 C and WC, Fe 3 C) This result highlight the reductive role that can play cellulose during the pyrolysis step that allows to tune the composition of M x O y /C composites. The materials were characterized by FTIR, Raman, TGA, XRD and SEM. This study highlights that cellulose can be used for a convenient preparation of a variety of highly demanded M x O y and M x O y /C composites with original shapes and morphologies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Oxidative dehydrogenation of n-butane over vanadium magnesium oxide catalysts supported on nano-structured MgO and ZrO2: effect of oxygen capacity of the catalyst.

    Science.gov (United States)

    Lee, Howon; Lee, Jong Kwon; Hong, Ung Gi; Song, In Kyu; Yoo, Yeonshick; Cho, Young-Jin; Lee, Jinsuk; Chang, Hosik; Jung, Ji Chul

    2012-07-01

    Vanadium-magnesium oxide catalysts supported on nano-structured MgO and ZrO2 (Mg3(VO4)2/MgO/ZrO2) were prepared by a wet impregnation method with a variation of Mg:Zr ratio (8:1, 4:1, 2:1, and 1:1). For comparison, Mg3(VO4)2/MgO and Mg3(VO4)2/ZrO2 catalysts were also prepared by a wet impregnation method. The prepared catalysts were applied to the oxidative dehydrogenation of n-butane in a continuous flow fixed-bed reactor. Mg3(VO4)2/MgO/ZrO2 (Mg:Zr = 4:1, 2:1, and 1:1) and Mg3(VO4)2/ZrO2 catalysts showed a stable catalytic activity during the whole reaction time, while Mg3(VO4)2/MgO/ZrO2 (8:1) and Mg3(VO4)2/MgO catalysts experienced a severe catalyst deactivation. Deactivation of Mg3(VO4)2/MgO/ZrO2 (8:1) and Mg3(VO4)2/MgO catalysts was due to their low oxygen mobility. Effect of oxygen capacity (the amount of oxygen in the catalyst involved in the reaction) of the supported Mg3(V04)2 catalysts on the catalytic performance in the oxidative dehydrogenation of n-butane was investigated. Experimental results revealed that oxygen capacity of the catalyst was closely related to the catalytic activity in the oxidative dehydrogenation of n-butane. A large oxygen capacity of the catalyst was favorable for obtaining a high catalytic activity in this reaction. Among the catalysts tested, Mg3(VO4)2/MgO/ZrO2 (4:1) catalyst with the largest oxygen capacity showed the best catalytic performance.

  15. Extraction of Vanadium from Stone Coal by Microwave Assisted Sulfation Roasting

    Science.gov (United States)

    Wang, Mingyu; Xian, Pengfei; Wang, Xuewen; Li, Bowen

    2015-02-01

    The extraction of vanadium from stone coal was investigated by microwave-assisted sulfation roasting followed by water leaching. The results showed that this process is an effective method for the extraction of vanadium from stone coal. Microwave-assisted sulfation roasting promotes the reaction of sulfuric acid with vanadium oxides and decreases roasting time. Under optimized conditions (roasting temperature 200°C, heating rate of 10°C/min, 25% sulfuric acid addition, water leaching at 75°C for 1 h, and liquid/solid ratio of 1.5 ml/g), the leaching rate of vanadium reached 92.6%.

  16. Organometalic carbosilane polymers containing vanadium and their preparation

    Science.gov (United States)

    Yajima, S.; Okamura, K.; Shishido, T.; Fukuda, K.

    1983-01-01

    The present invention concerns a new organometallic polymer material containing in part a vanadium-siloxane linkage (V-0-Si), which has excellent resistance to heat and oxidation and a high residue ratio after high temperature treatment in a non-oxidizing atmosphere, for example, nitrogen, argon, helium, ammonia, or hydrogen.

  17. Studies on phase and morphological evolution of silver vanadium oxides as a function of pH: evaluation of electrochemical behavior towards quantification of Pb2+ and Cd2+ ions

    Science.gov (United States)

    Gangaiah, Vijayakumar; Shivappa Adarakatti, Prashanth; Siddaramanna, Ashoka; Malingappa, Pandurangappa; Thimmanna Chandrappa, Gujjarahalli

    2017-08-01

    The effect of pH on morphological and phase evolution of silver vanadium oxide nanostructures are investigated under hydrothermal process. The results of powder x-ray diffraction (PXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) disclosed that the morphological evolution of nanobelts into nanoring structures occurs at pH in between 4 and 5 with Ag2V4O11 phase and nanobelt morphologies at pH from 6 to 7 with β-AgVO3 phase. The prepared Ag2V4O11 and β-AgVO3 have been evaluated for the simultaneous quantification of Pb2+ and Cd2+ ions in aqueous solution using differential pulse anodic stripping voltammetry. The results reveal that Ag2V4O11 shows better quantification result compared to β-AgVO3.

  18. An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite.

    Science.gov (United States)

    Chen, Desheng; Zhao, Hongxin; Hu, Guoping; Qi, Tao; Yu, Hongdong; Zhang, Guozhi; Wang, Lina; Wang, Weijing

    2015-08-30

    An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite was developed. In this study, a mixed solvent system of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) diluted with kerosene was used for the selective extraction of vanadium from a hydrochloric acid leaching solution that contained low vanadium concentration with high concentrations of iron and impurities of Ca, Mg, and Al. In the extraction process, the initial solution pH and the phase ratio had considerable functions in the extraction of vanadium from the hydrochloric acid leaching solution. Under optimal extraction conditions (i.e., 30-40°C for 10min, 1:3 phase ratio (O/A), 20% D2EHPA concentration (v/v), and 0-0.8 initial solution pH), 99.4% vanadium and only 4.2% iron were extracted by the three-stage counter-current extraction process. In the stripping process with H2SO4 as the stripping agent and under optimal stripping conditions (i.e., 20% H2SO4 concentration, 5:1 phase ratio (O/A), 20min stripping time, and 40°C stripping temperature), 99.6% vanadium and only 5.4% iron were stripped by the three-stage counter-current stripping process. The stripping solution contained 40.16g/LV2O5,0.691g/L Fe, 0.007g/L TiO2, 0.006g/L SiO2 and 0.247g/L CaO. A V2O5 product with a purity of 99.12% V2O5 and only 0.026% Fe was obtained after the oxidation, precipitation, and calcination processes. The total vanadium recovered from the hydrochloric acid leaching solution was 85.5%. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. On the regiospecificity of vanadium bromoperoxidase.

    Science.gov (United States)

    Martinez, J S; Carroll, G L; Tschirret-Guth, R A; Altenhoff, G; Little, R D; Butler, A

    2001-04-11

    Vanadium haloperoxidase enzymes catalyze the oxidation of halide ions by hydrogen peroxide, producing an oxidized intermediate, which can halogenate an organic substrate or react with a second equivalent of hydrogen peroxide to produce dioxygen. Haloperoxidases are thought to be involved in the biogenesis of halogenated natural products isolated from marine organisms, including indoles and terpenes, of which many are selectively oxidized or halogenated. Little has been shown concerning the ability of the marine haloperoxidases to catalyze regioselective reactions. Here we report the regiospecific bromoperoxidative oxidation of 1,3-di-tert-butylindole by V-BrPO from the marine algae Ascophyllum nodosum and Corallina officinalis. Both enzymes catalyze the regiospecific oxidation of 1,3-di-tert-butylindole in a reaction requiring both H(2)O(2) and Br(-) as substrates, but which produce the unbrominated 1,3-di-tert-butyl-2-indolinone product exclusively, in near quantitative yield (i.e. one H(2)O(2) consumed per product). By contrast, reactions with the controlled addition of aqueous bromine solution (HOBr = Br(2) = Br(3)(-)) produce three monobromo and one dibromo-2-indolinone products, all of which differ from the V-BrPO-catalyzed product. Further, reactivities of 1,3-di-tert-butyl-2-indolinone with both aqueous bromine and V-BrPO differ significantly and shed light onto the possible nature of the oxidizing intermediate. This is the first example of a regiospecific bromination by a vanadium haloperoxidase and further extends their usefulness as catalysts.

  20. Determination of V(IV) and V(V) by electrothermal atomic absorption spectrometry following selective solid-phase extraction and the study on the change in the oxidation state of vanadium species in seawater during the sample storage.

    Science.gov (United States)

    Nukatsuka, Isoshi; Shimizu, Yutaka; Ohzeki, Kunio

    2002-09-01

    The changes in the oxidation state of vanadium in artificial and natural seawater samples were studied by electrothermal atomic absorption spectrometry (ETAAS) with a direct injection of a resin suspension. V(IV) and V(V) were extracted as the complex with Chromazurol B and with N-cinnamoyl-N-2,3-xylylhydroxylamine, respectively, using a suspension of an anion-exchange resin and determined by ETAAS independently. The detection limits of both methods were 0.02 ng ml(-1) for 40 ml of a sample solution. The recovery tests for an artificial seawater sample spiked with V(IV) and/or V(V) were carried out carefully. The results showed that the recoveries of V(IV) or V(V) were 99.2-109% and the standard deviations were 1-6%. The total V was also determined after V(V) was reduced by ascorbic acid. In artificial seawater at pH 7.8, V(V) was stable but V(IV) was oxidized rapidly. In acidified artificial seawater (pH 2.0), V(IV) was oxidized slowly but only a small tendency of such reduction of V(V) was observed. In a natural seawater sample, V(IV) was not detected. The acidification of the natural seawater sample resulted in the reduction of V(V).

  1. Structural and catalytic properties of a novel vanadium containing ...

    Indian Academy of Sciences (India)

    Abstract. A novel vanadium containing solid core mesoporous silica shell catalyst was synthesized with different Si/V ratios by sol-gel method under neutral conditions. The synthesized materials were characterized by various techniques and gas phase diphenyl methane oxidation reaction. The mesoporosity combined with ...

  2. Optical properties of zinc–vanadium glasses doped with samarium ...

    Indian Academy of Sciences (India)

    Zinc–vanadium glasses doped with samarium oxide having the chemical composition Sm2O3() ZnO(40-)V2O5(60) (where = 0.1–0.5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been calculated.

  3. Research and development on vanadium alloys for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States); Matsui, H.; Abe, K. [Tohoku Univ. (Japan); Smith, D.L. [Argonne National Lab., IL (United States); Osch, E. van [NERF, Petten (Netherlands); Kazakov, V.A. [RIAR, Dimitrovgrad (Russian Federation)

    1998-03-01

    The current status of research and development on unirradiated and irradiated V-Cr-Ti alloys intended for fusion reactor structural applications is reviewed, with particular emphasis on the flow and fracture behavior of neutron-irradiated vanadium alloys. Recent progress on fabrication, joining, oxidation behavior, and the development of insulator coatings is also summarized. Fabrication of large (>500 kg) heats of V-4Cr-4Ti with properties similar to previous small laboratory heats has now been demonstrated. Impressive advances in the joining of thick sections of vanadium alloys using GTA and electron beam welds have been achieved in the past two years, although further improvements are still needed.

  4. Vanadium-modified molecular sieves: preparation, characterization and catalysis

    Directory of Open Access Journals (Sweden)

    Ângela A. Teixeira-Neto

    2009-01-01

    Full Text Available Vanadium-containing molecular sieves are redox catalysts and are good candidates as substitutes for oxide-supported V2O5 in a number of reactions. These materials have the advantage of presenting better dispersion of vanadium species, as well as shape-selective properties and controllable acidities. They may be prepared by one-pot synthesis or by post-synthesis methods and a number of techniques such as diffuse reflectance UV-visible spectroscopy, 51V nuclear magnetic resonance and electron paramagnetic resonance, to name but a few, have been used to characterize these materials. In this review, methods of preparation of vanadium-modified molecular sieves, their characterization and applications in catalysis are discussed.

  5. The determination of vanadium in brines by atomic absorption spectroscopy

    Science.gov (United States)

    Crump-Wiesner, Hans J.; Feltz, H.R.; Purdy, W.C.

    1971-01-01

    A standard addition method is described for the determination of vanadium in brines by atomic absorption spectroscopy with a nitrous oxide-acetylene flame. Sample pH is adjusted to 1.0 with concentrated hydrochloric acid and the vanadium is directly extracted with 5% cupferron in methyl isobutyl ketone (MIBK). The ketone layer is then aspirated into the flame and the recorded absorption values are plotted as a function of the concentration of the added metal. As little as 2.5 ??g l-1 of vanadium can be detected under the conditions of the procedure. Tungsten and tin interfere when present in excess of 5 and 10 ??g ml-1, respectively. The concentrations of the two interfering ions normally found in brines are well below interference levels. ?? 1971.

  6. Analysis and measurement of the electrolyte imbalance in a vanadium redox flow battery

    Science.gov (United States)

    Ngamsai, Kittima; Arpornwichanop, Amornchai

    2015-05-01

    Electrolyte imbalance in vanadium redox flow batteries is an important problem for its long-term operation as it leads to loss of energy. To address this problem, a modified open circuit voltage (OCV) cell is developed by adding a middle half cell between the negative and positive half cells of a conventional OCV cell and used to predict the oxidation state of vanadium in the electrolyte solution from the measured voltage in each side of the electrolyte (positive and negative). The correlation between the oxidation state of vanadium and cell voltage is explained by a basic electrochemical principle and the Nernst equation. The experimental results show that at different oxidation states of vanadium, the predicted OCV agrees reasonably with the experimental data. In addition, the effect of the state of charge (SOC) and electrolyte imbalance on the energy capacity of a cell is discussed.

  7. The role of vanadium in the chemical defense of the solitary tunicate, Phallusia nigra.

    Science.gov (United States)

    Odate, Shobu; Pawlik, Joseph R

    2007-03-01

    Ascidians (sea squirts) may defend themselves from predators, biofouling competitors, and bacterial infection by producing secondary metabolites or sequestering acid, but many species also accumulate heavy metals, most notably vanadium. The defensive functions of heavy metals in ascidians remain unclear, and to this end, the solitary Caribbean tunicate, Phallusia nigra, was studied to localize vanadium in its tissues and to assess the defensive properties of vanadium-containing compounds. As determined by flame atomic absorption spectroscopy, the internal tissues and blood contained the highest vanadium concentrations (mean values of 2280 and 1886 ppm dry mass, respectively), followed by the tunic surface (871 ppm dry mass). Results of laboratory feeding assays with the bluehead wrasse, Thalassoma bifasciatum, confirmed outcomes of past studies that demonstrated that vanadyl sulfate (VOSO4.6H20) and sodium vanadate (Na3VO4) were unpalatable to fish, although these salts do not accurately reflect the chelation environment or oxidation state of vanadium in living tunicates. Fresh preparations of whole tunic, internal tissues, and blood were unpalatable to fish, but freezing and thawing of internal tissues and blood rendered them palatable. Crude organic extracts of whole tunic and internal tissues contained vanadium metabolites (225 and 750 ppm dry mass, respectively) and were palatable to T. bifasciatum; crude extracts also exhibited no antimicrobial effects against a panel of four marine bacteria known to be pathogens of marine invertebrates (Vibrio parahaemolyticus, Vibrio harveyi, Leucothrix mucor, and Deleya marina). Nonacidic vanadium (+3) complexes neither deterred predation nor inhibited microbial growth, whereas acidic aqua vanadium (+3 and +4) complexes were unpalatable to 7 bifasciatum and exhibited antimicrobial activity. Difficulties in decoupling low pH from oxidation state and chelation environment of vanadium prevent definitive conclusions about the

  8. Impedance spectroscopy study and phase transition in phospho-vanadium mixed oxide LiZnV0.5P0.5O4

    Science.gov (United States)

    Rahal, A.; Megdiche Borchani, S.; Guidara, Kamel; Megdiche, Makram

    2017-08-01

    An X-ray crystallographic study has allowed us to identify a powder of the type LiZnV0.5P0.5O4, which contains 50% of vanadium and 50% of phosphore, inside the binary system LiZnVO4-LiZnPO4. The structure is isotypic with the phenacite like LiZnP04. X-ray diffraction patterns are indexed according to the lattice parameters of the rhombohedral system and the R3 space group. IR spectra show the presence of VO4 and PO4 groups in the network of this material. The experimental results indicate that σ_{AC}(ω) is proportional to ( {ωn } ). The activation energy found from the Arrhenius plot confirms that the conduction processing of the material is not due to simple hopping mechanism. The temperature dependence of frequency exponent n was investigated to understanding the conduction mechanism in LiZnV0.5P0.5O4. The non-overlapping small Polaron tunneling (NSPT) model can explain the temperature dependence of the frequency exponent. A phase transition at T = 623 K has been evidenced by Differential scanning calorimetry (DSC) and subsequently confirmed by the analysis of dielectric and electric properties.

  9. Nano crystalline Bi{sub 2}(VO{sub 5}) phases in lithium bismuth borate glasses containing mixed vanadium-nickel oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Arti, E-mail: artidabhur@gmail.com; Khasa, S.; Dahiya, M. S. [Department of Physics, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, India-131039 (India); Agarwal, A. [Department of Applied Physics, G. J. University of Science and Technology, Hisar, India-125001 (India)

    2016-05-23

    Glass composition 7V{sub 2}O{sub 5}·23Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3} and x(2NiO·V{sub 2}O{sub 5})·(30-x)Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3}, x=0, 2, 5, 7 and 10, were produced by conventional melt quenching technique. The quenched amorphous glass samples were annealed at temperatures 400°C and 500°C for 6 hours. The Bi{sub 2}(VO{sub 5}) crystallite were grown in all prepared glass matrix. Tn vanadium lithium bismuth borate glass (annealed), the some phrase of V{sub 2}O{sub 5}-crystal were observed along with the nano crystalline Bi{sub 2}(VO{sub 5}) phase. The sharp peaks in FTTR spectra of all annealed compositions were also compatible with the XRD diffraction peaks of the system under investigation. Average crystalline size (D) of the Bi{sub 2}(VO{sub 5}) nano-crystallite was ~30 nm for samples annealed at 400°C and ~42 nm for samples annealed at 500°C. Lattice parameter and the lattice strain for all the samples was also calculated corresponding to the (113) plane of Bi{sub 2}(VO{sub 5}) crystallite.

  10. Determination of Vanadium Binding Mode on Seawater-Contacted Polyamidoxime Adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhicheng [Lawrence Berkeley National Laboratory (LBNL); Rao, Linfeng [Lawrence Berkeley National Laboratory (LBNL); Abney, Carter W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bryantsev, Vyacheslav [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ivanov, Aleksandr [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-09-01

    Adsorbents developed for the recovery of uranium from seawater display poor selectivity over other transition metals present in the ocean, with vanadium particularly problematic. To improve selectivity, an indispensable step is the positive identification of metal binding environments following actual seawater deployment. In this work we apply x-ray absorption fine structure (XAFS) spectroscopy to directly investigate the vanadium binding environment on seawater-deployed polyamidoxime adsorbents. Comparison of the x-ray absorption near edge spectra (XANES) reveal marked similarities to recently a reported non-oxido vanadium (V) structure formed upon binding with cyclic imidedioxime, a byproduct of generating amidoxime functionalities. Density functional theory (DFT) calculations provided a series of putative vanadium binding environments for both vanadium (IV) and vanadium (V) oxidation states, and with both amidoxime and cyclic imidedioxime. Fits of the extended XAFS (EXAFS) data confirmed vanadium (V) is bound exclusively by the cyclic imidedioxime moiety in a 1:2 metal:ligand fashion, though a modest structural distortion is also observed compared to crystal structure data and computationally optimized geometries which is attributed to morphology effects from the polymer graft chain and the absence of crystal packing interactions. These results demonstrate that improved selectivity for uranium over vanadium can be achieved by suppressing the formation of cyclic imidedioxime during preparation of polyamidoxime adsorbents for seawater uranium recovery.

  11. Vanadium As a Potential Membrane Material for Carbon Capture: Effects of Minor Flue Gas Species.

    Science.gov (United States)

    Yuan, Mengyao; Liguori, Simona; Lee, Kyoungjin; Van Campen, Douglas G; Toney, Michael F; Wilcox, Jennifer

    2017-10-03

    Vanadium and its surface oxides were studied as a potential nitrogen-selective membrane material for indirect carbon capture from coal or natural gas power plants. The effects of minor flue gas components (SO 2 , NO, NO 2 , H 2 O, and O 2 ) on vanadium at 500-600 °C were investigated by thermochemical exposure in combination with X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and in situ X-ray diffraction (XRD). The results showed that SO 2 , NO, and NO 2 are unlikely to have adsorbed on the surface vanadium oxides at 600 °C after exposure for up to 10 h, although NO and NO 2 may have exhibited oxidizing effects (e.g., exposure to 250 ppmv NO/N 2 resulted in an 2.4 times increase in surface V 2 O 5 compared to exposure to just N 2 ). We hypothesize that decomposition of surface vanadium oxides and diffusion of surface oxygen into the metal bulk are both important mechanisms affecting the composition and morphology of the vanadium membrane. The results and hypothesis suggest that the carbon capture performance of the vanadium membrane can potentially be strengthened by material and process improvements such as alloying, operating temperature reduction, and flue gas treatment.

  12. Brain Metal Distribution and Neuro-Inflammatory Profiles after Chronic Vanadium Administration and Withdrawal in Mice

    OpenAIRE

    Folarin, Oluwabusayo R.; Snyder, Amanda M.; Peters, Douglas G.; Funmilayo Olopade; Connor, James R.; Olopade, James O

    2017-01-01

    Vanadium is a potentially toxic environmental pollutant and induces oxidative damage in biological systems including the central nervous system (CNS). Its deposition in brain tissue may be involved in the pathogenesis of certain neurological disorders which after prolonged exposure can culminate into more severe pathology. Most studies on vanadium neurotoxicity have been done after acute exposure but in reality some populations are exposed for a lifetime. This work was designed to ascertain n...

  13. Selective extraction of vanadium from the APV-precipitated waste water

    Science.gov (United States)

    Li, Cui; Li, Hong-Yi; Tu, Chun-Bin; Zhang, Tao; Fang, Hai-Xing; Xie, Bing

    In the process of precipitating ammonium polyvanadate (APV) to produce vanadium pentoxide in Pan-steel in China, rest waste water usually contains about 24 333mg/L V(V), 2 100g/L Cr(VI),20 500mg/L Si(IV) and 20 100g/L Na2SO4. In order to recover valuable and also toxic metal ions contained in the waste water, effective extraction method of using anion exchange resin was realized to extract Vanadium selectively, leading to effective separation between vanadium and chromium. To ensure vanadium was absorbed by the resin, V(V) and Cr(VI) were reduced to V(IV) and Cr(III) by NaHSO3, respectively, and then V(IV) was oxidized by H2O2 to V(V) anions. Effects of temperature, solution pH, concentration of ions and absorbing time on vanadium absorption rate were investigated. Chromium was precipitated from rest solution while vanadium was eluted from resin by NaOH solution and then precipitated. Results showed that vanadium recovery of 73% could be obtained in optimized condition. The resin could be regenerated by 3% hydrochloric acid, which indicated the recyclability of the resin and thus low cost of this established method.

  14. Exploring the chemistry and biology of vanadium-dependent haloperoxidases.

    Science.gov (United States)

    Winter, Jaclyn M; Moore, Bradley S

    2009-07-10

    Nature has developed an exquisite array of methods to introduce halogen atoms into organic compounds. Most of these enzymes are oxidative and require either hydrogen peroxide or molecular oxygen as a cosubstrate to generate a reactive halogen atom for catalysis. Vanadium-dependent haloperoxidases contain a vanadate prosthetic group and utilize hydrogen peroxide to oxidize a halide ion into a reactive electrophilic intermediate. These metalloenzymes have a large distribution in nature, where they are present in macroalgae, fungi, and bacteria, but have been exclusively characterized in eukaryotes. In this minireview, we highlight the chemistry and biology of vanadium-dependent haloperoxidases from fungi and marine algae and the emergence of new bacterial members that extend the biological function of these poorly understood halogenating enzymes.

  15. Exploring the Chemistry and Biology of Vanadium-dependent Haloperoxidases*

    Science.gov (United States)

    Winter, Jaclyn M.; Moore, Bradley S.

    2009-01-01

    Nature has developed an exquisite array of methods to introduce halogen atoms into organic compounds. Most of these enzymes are oxidative and require either hydrogen peroxide or molecular oxygen as a cosubstrate to generate a reactive halogen atom for catalysis. Vanadium-dependent haloperoxidases contain a vanadate prosthetic group and utilize hydrogen peroxide to oxidize a halide ion into a reactive electrophilic intermediate. These metalloenzymes have a large distribution in nature, where they are present in macroalgae, fungi, and bacteria, but have been exclusively characterized in eukaryotes. In this minireview, we highlight the chemistry and biology of vanadium-dependent haloperoxidases from fungi and marine algae and the emergence of new bacterial members that extend the biological function of these poorly understood halogenating enzymes. PMID:19363038

  16. Improvement on Performance of Mg-C Refractories as Lining of Vanadium-Extraction Converters

    Science.gov (United States)

    Huang, Weijun; Xu, Lei; Zhang, Shuai; Chen, Min

    For the purpose of extending the service life of MgO-C bricks used as linings of vanadium-extraction converters, the effect of Fe addition on properties of MgO-C bricks was investigated. The results showed the addition of Fe could effectively improve the sinterability of the oxidized layer of the MgO-C refractory at 1400°C due to the effect of FeO (formed by oxidation of Fe) on formation of MgO-FeOss and modification of the microstructure, and excellent corrosion resistance against vanadium containing slag was also obtained due to the increase of compactness of the oxidized layer and concentration of FeO in the oxidized layer. Consequently, it is considered that MgO-C brick by introducing the new phase of Fe is a favorable substitute of MgO-C refractory to be used as linings of vanadium-extraction converters.

  17. The Cooling Ability Study on CO2 and O2 Mixed Injection in Vanadium Extraction Process

    Science.gov (United States)

    Li, Pengcheng; Wang, Yu; Du, Wei-Tong; Wen, Gang

    Carbon dioxide could be utilized as a weak oxidant and a kind of coolant to oxidize elements, meanwhile, helping control the temperature during the converter vanadium extraction process. However, the optimum content of CO2 and the cooling effect of CO2 at low content have not been reported. In this study, experimental research based on the influence of different CO2 contents from 0% to 25% injected to the vanadium-containing hot metal was carried out, as well as contrast experiments of O2-N2 mixed blowing. The results indicated that the optimum content of CO2 was 15%. Under the optimum condition, the oxidation of [C] was the lowest and the oxidation rate of [V] was 96.9%, while the temperature was also lower than the O2-N2 mixed blowing. This paper provide a potential property for utilizing CO2 during the converter vanadium extraction process.

  18. Optical properties of zinc–vanadium glasses doped with samarium ...

    Indian Academy of Sciences (India)

    Abstract. Zinc–vanadium glasses doped with samarium oxide having the chemical composition Sm2O3(x). ZnO(40−x)V2O5(60)(where x = 0·1–0·5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been ...

  19. Characterization of vanadium flow battery

    Energy Technology Data Exchange (ETDEWEB)

    Bindner, H.; Ekman, C.; Gehrke, O.; Isleifsson, F.

    2010-10-15

    This report summarizes the work done at Risoe DTU testing a vanadium flow battery as part of the project 'Characterisation of Vanadium Batteries' (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risoe DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses are power conversion in cell stacks/electrolyte, power converter, and auxiliary power consumption from pumps and controller. The response time for the battery is limited at 20kW/s by the ramp rate of the power converter. The battery can thus provide power and frequency support for the power system. Vanadium battery is a potential technology for storage based services to the power system provided investment and O and M cost are low enough and long term operation is documented. (Author)

  20. Chemical speciation of vanadium in particulate matter emitted from diesel vehicles and urban atmospheric aerosols.

    Science.gov (United States)

    Shafer, Martin M; Toner, Brandy M; Overdier, Joel T; Schauer, James J; Fakra, Sirine C; Hu, Shaohua; Herner, Jorn D; Ayala, Alberto

    2012-01-03

    We report on the development and application of an integrated set of analytical tools that enable accurate measurement of total, extractable, and, importantly, the oxidation state of vanadium in sub-milligram masses of environmental aerosols and solids. Through rigorous control of blanks, application of magnetic-sector-ICPMS, and miniaturization of the extraction/separation methods we have substantially improved upon published quantification limits. The study focused on the application of these methods to particulate matter (PM) emissions from diesel vehicles, both in baseline configuration without after-treatment and also equipped with advanced PM and NO(x) emission controls. Particle size-resolved vanadium speciation data were obtained from dynamometer samples containing total vanadium pools of only 0.2-2 ng and provide some of the first measurements of the oxidation state of vanadium in diesel vehicle PM emissions. The emission rates and the measured fraction of V(V) in PM from diesel engines running without exhaust after-treatment were both low (2-3 ng/mile and 13-16%, respectively). The V(IV) species was measured as the dominant vanadium species in diesel PM emissions. A significantly greater fraction of V(V) (76%) was measured in PM from the engine fitted with a prototype vanadium-based selective catalytic reductors (V-SCR) retrofit. The emission rate of V(V) determined for the V-SCR equipped vehicle (103 ng/mile) was 40-fold greater than that from the baseline vehicle. A clear contrast between the PM size-distributions of V(V) and V(IV) emissions was apparent, with the V(V) distribution characterized by a major single mode in the ultrafine (vanadium-containing fine-particle PM from the V-SCR identified V(2)O(5) as the dominant vanadium species.

  1. Brain Metal Distribution and Neuro-Inflammatory Profiles after Chronic Vanadium Administration and Withdrawal in Mice

    Directory of Open Access Journals (Sweden)

    Oluwabusayo R. Folarin

    2017-07-01

    Full Text Available Vanadium is a potentially toxic environmental pollutant and induces oxidative damage in biological systems including the central nervous system (CNS. Its deposition in brain tissue may be involved in the pathogenesis of certain neurological disorders which after prolonged exposure can culminate into more severe pathology. Most studies on vanadium neurotoxicity have been done after acute exposure but in reality some populations are exposed for a lifetime. This work was designed to ascertain neurodegenerative consequences of chronic vanadium administration and to investigate the progressive changes in the brain after withdrawal from vanadium treatment. A total of 85 male BALB/c mice were used for the experiment and divided into three major groups of vanadium treated (intraperitoneally (i.p. injected with 3 mg/kg body weight of sodium metavanadate and sacrificed every 3 months till 18 months; matched controls; and animals that were exposed to vanadium for 3 months and thereafter the metal was withdrawn. Brain tissues were obtained after animal sacrifice. Sagittal cut sections of paraffin embedded tissue (5 μm were analyzed by the Laser ablation-inductively coupled plasma-mass spectrometry (LA–ICP–MS to show the absorption and distribution of vanadium metal. Also, Haematoxylin and Eosin (H&E staining of brain sections, and immunohistochemistry for Microglia (Iba-1, Astrocytes (GFAP, Neurons (Neu-N and Neu-N + 4′,6-diamidine-2′-pheynylindole dihydrochloride (Dapi Immunofluorescent labeling were observed for morphological and morphometric parameters. The LA–ICP–MS results showed progressive increase in vanadium uptake with time in different brain regions with prediction for regions like the olfactory bulb, brain stem and cerebellum. The withdrawal brains still show presence of vanadium metal in the brain slightly more than the controls. There were morphological alterations (of the layering profile, nuclear shrinkage in the prefrontal

  2. [The vanadium compounds: chemistry, synthesis, insulinomimetic properties].

    Science.gov (United States)

    Fedorova, E V; Buriakina, A V; Vorob'eva, N M; Baranova, N I

    2014-01-01

    The review considers the biological role of vanadium, its participation in various processes in humans and other mammals, and the anti-diabetic effect of its compounds. Vanadium salts have persistent hypoglycemic and antihyperlipidemic effects and reduce the probability of secondary complications in animals with experimental diabetes. The review contains a detailed description of all major synthesized vanadium complexes having antidiabetic activity. Currently, vanadium complexes with organic ligands are more effective and safer than the inorganic salts. Despite the proven efficacy of these compounds as the anti-diabetic agents in animal models, only one organic complex of vanadium is currently under the second phase of clinical trials. All of the considered data suggest that vanadium compound are a new promising class of drugs in modern pharmacotherapy of diabetes.

  3. Study of sulfur and vanadium in heavy petroleum products

    Energy Technology Data Exchange (ETDEWEB)

    Novelli, J.M.

    1982-10-01

    Sulfur compounds in heavy oil fractions (>450/sup 0/C) are studied in the first part of this work. After chemical oxidation by metachloroperbenzoic acid to obtain sulfones, sulfur compounds are analyzed by infrared spectroscopy for their qualitative and quantitative repartition. The method can be applied for the study of sulfur containing molecules before and after structural modifications of petroleum fractions by any chemical refining processes. In a second part vanadium is characterized in asphalt by physicochemical and chemical methods. 80% of the vanadium in a Boscan asphalt is under the form of porphyrins. Different associations are evidenced in petroleum fractions and metalloporphyrins, but the liaison between the vanadyl group and heterocondensate from asphalts is the more frequent.

  4. Is vanadium a more versatile target in the activity of primordial life forms than hitherto anticipated?

    Science.gov (United States)

    Rehder, Dieter

    2008-03-21

    The two predominant forms of vanadium occurring in the geo-, aqua- and biosphere, soluble vanadate(V) and insoluble oxovanadium(IV) (vanadyl), are subject to bacterial activity and transformation. Bacteria belonging to genera such as Shewanella, Pseudomonas and Geobacter can use vanadate as a primary electron acceptor in dissimilation or respiration, an important issue in the context of biomineralisation and soil detoxification. Azotobacter, which can employ vanadium as an essential element in nitrogen fixation, secretes a vanadophore which enables the uptake of vanadium(V). Siderophores secreted by other bacteria competitively (to ferric iron) take up vanadyl and thus interfere with iron supply, resulting in bacteriostasis. The halo-alkaliphilic Thioalkalivibrio nitratireducens possibly uses vanadium as a constituent of an alternative, molybdopterin-free nitrate reductase. Marine macro-algae can generate a variety of halogenated organic compounds by use of vanadate-dependent haloperoxidases, and a molecular vanadium compound, amavadin, from Amanita mushrooms has turned out to be an efficient catalyst in oxidation reactions. The present account is a focused and critical review of the current knowledge of the interplay of bacteria and other primitive forms of life (cyanobacteria, algae, fungi and lichens) with vanadium, with the aim to provide perspectives for applications and further investigations.

  5. Effects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene film

    KAUST Repository

    Atiqullah, M.

    2012-07-01

    A Group 5 post-metallocene precatalyst, (ONO)VCl(THF) 2 (ONO = a bis(phenolate)pyridine LX 2 pincer ligand), activated with modified methylaluminoxane (MMAO-3A) produced a linear ethylene homopolymer (nm-HomoPE)and an unusual inhomogeneous copolymer (nm-CopolyPE) with 1-hexene having very low backbone unsaturation. The nm-CopolyPE inhomogeneity was reflected in the distributions of short chain branches, 1-hexene composition, and methylene sequence length. The 1-hexene incorporation into the polyethylene backbone strongly depended on the molecular weight of the growing polymer chain. (ONO)VCl(THF) 2, because of site diversity and easier removal of a tertiary (vs. a secondary) hydrogen, produced a skewed short chain branching (SCB) profile, incorporating 1-hexene more efficiently in the low molecular weight region than in the high molecular weight region. The significant decrease in molecular weight by 1-hexene showed that the (ONO)VCl(THF) 2 catalytic sites were also highly responsive to chain-transfer directly to 1-hexene itself, producing vinyl and trans-vinylene termini. Subsequently, the effect of backbone inhomogeneity on the UV oxidative degradation of films made from both polyethylenes was investigated. The major functional group accumulated in the branched nm-CopolyPE film was carbonyl followed by carboxyl, then vinyl/ester, whereas that in the linear nm-HomoPE film was carboxyl. However, (carbonyl, carboxyl, vinyl, and ester) nm-CopolyPE film >> (carboxyl) nm-HomoPE film). The distributions of the tertiary C-H sites and methylene sequence length in the branched nm-CopolyPE film enhanced abstraction of H, decomposition of hydroperoxide group ROOH, and generation of carbonyl compounds as compared with those in the linear nm-HomoPE film. This clearly establishes the role played by the backbone inhomogeneity. The effect of short chain branches and sequence length distributions on peak melting temperature T pm, and most probably lamellar thickness L o, was

  6. Characterization of Vanadium Flow Battery

    DEFF Research Database (Denmark)

    Bindner, Henrik W.; Krog Ekman, Claus; Gehrke, Oliver

    This report summarizes the work done at Risø-DTU testing a vanadium flow battery as part of the project “Characterisation of Vanadium Batteries” (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery...... has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risø DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration...... of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses...

  7. Solvothermal synthesis of vanadium phosphates in the form of xerogels, aerogels and mesostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sydorchuk, V.; Zazhigalov, V. [Institute of Sorption and Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., Kyiv 03164 (Ukraine); Khalameida, S., E-mail: svkhal@ukr.net [Institute of Sorption and Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., Kyiv 03164 (Ukraine); Diyuk, E. [Institute of Sorption and Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., Kyiv 03164 (Ukraine); Skubiszewska-Zieba, J.; Leboda, R. [Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 3, 20-031 Lublin (Poland); Kuznetsova, L. [Institute of Sorption and Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., Kyiv 03164 (Ukraine)

    2010-09-15

    Regularities and peculiarities of physicochemical changes, first of all phase transformations, during solvothermal treatment (with conventional and microwave heating) of the vanadium pentoxide and orthophosphoric acid mixture in organic solvents in the presence of reducing agents have been studied. Hemihydrate of vanadium hydrophosphate - the precursor of vanadium pyrophosphate, the active phase for n-butane to maleic anhydride oxidation, and ion exchanger with variable physicochemical characteristics, i.e. crystal structure, specific surface area, crystallite size and acidic properties - has been synthesized in the temperature range 170-200 {sup o}C. The obtained phases were examined using XRD, DTA-TG, SEM, FTIR spectroscopy, nitrogen adsorption as well as gas chromatographic determination of acidity through organic bases adsorption. The catalytic activity of prepared samples for n-butane oxidation has been investigated.

  8. Adsorption of Vanadium (V) from SCR Catalyst Leaching Solution and Application in Methyl Orange.

    Science.gov (United States)

    Sha, Xuelong; Ma, Wei; Meng, Fanqing; Wang, Ren; Fuping, Tian; Wei, Linsen

    2016-12-01

      In this study, we explored an effective and low-cost catalyst and its adsorption capacity and catalytic capacity for Methyl Orange Fenton oxidation degradation were investigated. The catalyst was directly prepared by reuse of magnetic iron oxide (Fe3O4) after saturated adsorption of vanadium (V) from waste SCR (Selective Catalytic Reduction) catalyst. The obtained catalyst was characterized by FTIR, XPS and the results showed that vanadium (V) adsorption process of Fe3O4 nanoparticles was non-redox reaction. The effects of pH, adsorption kinetics and equilibrium isotherms of adsorption were assessed. Adsorption of vanadium (V) ions by Fe3O4 nanoparticles could be well described by the Sips isotherm model which controlled by the mixed surface reaction and diffusion (MSRDC) adsorption kinetic model. The results show that vanadium (V) was mainly adsorbed on external surface of the Fe3O4 nanoparticles. The separation-recovering tungsten (VI) and vanadium (V) from waste SCR catalyst alkaline solution through pH adjustment was also investigated in this study. The results obtained from the experiments indicated that tungsten (VI) was selectively adsorbed from vanadium (V)/tungsten (VI) mixed solution in certain acidic condition by Fe3O4 nanoparticle to realize their recovery. Tungsten (V) with some impurity can be obtained by releasing from adsorbent, which can be confirmed by ICP-AES. The Methyl Orange degradation catalytic performance illustrated that the catalyst could improve Fenton reaction effectively at pH = 3.0 compare to Fe3O4 nanoparticles alone. Therefore, Fe3O4 nanoparticle adsorbed vanadium (V) has a potential to be employed as a heterogeneous Fenton-like catalyst in the present contribution, and its catalytic activity was mainly evaluated in terms of the decoloration efficiency of Methyl Orange.

  9. Leaching characteristics of vanadium in mine tailings and soils near a vanadium titanomagnetite mining site.

    Science.gov (United States)

    Yang, Jinyan; Tang, Ya; Yang, Kai; Rouff, Ashaki A; Elzinga, Evert J; Huang, Jen-How

    2014-01-15

    A series of column leaching experiments were performed to understand the leaching behaviour and the potential environmental risk of vanadium in a Panzhihua soil and vanadium titanomagnetite mine tailings. Results from sequential extraction experiments indicated that the mobility of vanadium in both the soil and the mine tailings was low, with vanadium readily mobilised. Column experiments revealed that only vanadium in the soil and mine tailing was leachable. The vanadium concentrations in the soil leachates did not vary considerably, but decreased with the leachate volume in the mine tailing leachates. This suggests that there was a smaller pool of leachable vanadium in the mine tailings compared to that in the soil. Drought and rewetting increased the vanadium concentrations in the soil and mine tailing leachates from 20μgL(-1) to 50-90μgL(-1), indicating the potential for high vanadium release following periods of drought. Experiments with soil columns overlain with 4, 8 and 20% volume mine tailings/volume soil exhibited very similar vanadium leaching behaviour. These results suggest that the transport of vanadium to the subsurface is controlled primarily by the leaching processes occurring in soils. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Functional and morphological olfactory bulb modifications in mice after vanadium inhalation.

    Science.gov (United States)

    Colín-Barenque, Laura; Pedraza-Chaverri, Jose; Medina-Campos, Omar; Jimenez-Martínez, Ruben; Bizarro-Nevares, Patricia; González-Villalva, Adriana; Rojas-Lemus, Marcela; Fortoul, Teresa I

    2015-02-01

    Neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases, have olfaction impairment. These pathologies have also been linked to environmental pollutants. Vanadium is a pollutant, and its toxic mechanisms are related to the production of oxidative stress. In this study, we evaluated the effects of inhaled vanadium on olfaction, the olfactory bulb antioxidant, through histological and ultrastructural changes in granule cells. Mice in control group were made to inhale saline; the experimental group inhaled 0.02-M vanadium pentoxide (V2O5) for 1 hr twice a week for 4 weeks. Animals were sacrificed at 1, 2, 3, and 4 weeks after inhalation. Olfactory function was evaluated by the odorant test. The activity of glutathione peroxidase (GPx) and glutathione reductase (GR) was assayed in olfactory bulbs and processed for rapid Golgi method and ultrastructural analysis. Results show that olfactory function decreased at 4-week vanadium exposure; granule cells showed a decrease in dendritic spine density and increased lipofuscin, Golgi apparatus vacuolation, apoptosis, and necrosis. The activity of GPx and GR in the olfactory bulb was increased compared to that of the controls. Our results demonstrate that vanadium inhalation disturbs olfaction, histology, and the ultrastructure of the granule cells that might be associated with oxidative stress, a risk factor in neurodegenerative diseases. © 2014 by The Author(s).

  11. Protection against vanadium-induced testicular toxicity by testosterone propionate in rats.

    Science.gov (United States)

    Chandra, Amar K; Ghosh, Rituparna; Chatterjee, Aparajita; Sarkar, Mahitosh

    2010-07-01

    Vanadium is a well recognized industrial hazard known to adversely affect male reproductive functions. The intricate mechanistic aspects of this metal and the role of oxidative stress in the deterioration of testicular functions are investigated in the current study. The experiment also focused on the effects of testosterone propionate in testicular and sperm functions in the rat intoxicated with vanadate. Vanadium exposure resulted in a more prominent spermatogenic arrest and consistently abolished the conversion of round to mature spermatids along with decreased epididymal sperm number and increased percentage of abnormal sperm. This is followed by a precipitous decline in the level of serum testosterone and gonadotropins and consequently the testicular steroidogenic and antioxidant enzymes were inhibited. Vanadium induces degeneration in the genital organs of rats and exhibits high indices of lipid oxidative damage. In response to exogenous testosterone propionate (TP) administration, spermatogonial cell populations remained suppressed, while the spermatogenesis was restored quantitatively. In contrast, the hormone treatment had no effect on the dramatically decreased serum FSH level after vanadate treatment. Moreover, TP could ameliorate the toxicity, as indicated by decreased testicular lipid peroxidation with marginal but significant increase in the activities of all the measured enzymes following vanadate-treatment. Taken together all these studies establish that vanadium is a testicular toxicant that perturbs the male reproductive system adversely. However, hormone replacement therapy by testosterone propionate may provide partial protection. The results suggest the feasibility of using endocrine regimens to impede deleterious effects of vanadium on the male reproductive system.

  12. Vanadium and iron complexes for catalytic oxidation

    NARCIS (Netherlands)

    Ligtenbarg, Alette Gerda Jeannet

    2001-01-01

    anadium werd in 1802 in Mexico ontdekt door Andres Manuel del Rio als bestanddeel van een mineraal. Een Frans chemicus was echter van mening dat het hier ging om onzuiver chroom, en de ontdekking werd daarom weer ingetrokken. Het element werd herontdekt in 1831 door de Zweedse chemicus Nils Gabriel

  13. Fast imaging of laser induced plasma emission of vanadium dioxide (VO2) target

    CSIR Research Space (South Africa)

    Masina, BN

    2013-10-01

    Full Text Available The main objective of this study is to fully optimise the synthesis of vanadium oxide nanostructures using pulsed laser deposition. We will attempt to realise this by studying the mechanism of the plasma formation and expansion during the pulsed...

  14. Interaction of vanadium and phosphorus in chicks.

    Science.gov (United States)

    Hill, C H

    1994-12-01

    Studies were carried out to determine the effect of dietary vanadium on chicks fed phosphorus deficient and control diets. Vanadium at 50 mg/kg of diet decreased growth of both control and deficient chicks. The high mortality among the phosphorus deficient chicks was significantly alleviated by the presence of vanadium. The increased relative ventricular weights found among the deficient chicks was also alleviated by the presence of dietary vanadium. Vanadium fed at 10 or 20 mg/kg diet did not reduce growth rate but significantly reduced mortality among chicks fed the deficient diet and decreased the relative ventricle weights. Time course studies revealed that chicks are hatched with high relative ventricular weights (.83% of body wt) and remain at that level among chicks fed the phosphorus deficient diet. The addition of vanadium or phosphate to the diet resulted in a progressive decrease in relative ventricular weights. The inclusion of vanadium in the diet resulted in increased serum phosphorus levels among the deficient chicks that may be related to the decrease in mortality and relative ventricle weights.

  15. Enhancing the Electronic Conductivity of Vanadium-tellurite Glasses by Tuning the Redox State

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Yue, Yuanzheng

    Transition metal oxides are used in a variety of electronic purposes, e.g., vanadium tellurite as cathode material in high-power demanding batteries. By tuning the redox state of vanadium, it is possible to achieve a lower internal resistance within the entire battery unit, thus a higher capacity....... In this work we vary the redox state of a given vanadium tellurite system by performing post heat-treatment in controlled atmosphere. This process is in theory not limited only to varying electronic conductivity, but also varying the glass structure, and hence, changing properties of the glasses, e.g, thermal...... and mechanical properties. Finally we give insight into the relation between the redox state and electronic conductivity....

  16. Fascinating and challenging role of tungstate promoted vanadium phosphate towards solvent free esterification of oleic acid.

    Science.gov (United States)

    Behera, Gobinda Chandra; Parida, K M

    2012-01-28

    A novel solid acid catalyst has been extensively used for the esterification reaction. Herein, tungstate promoted vanadium phosphate material is fabricated from its precursor, VOHPO(4)·0.5H(2)O and its catalytic activities and structure are investigated in detail. This kind of catalyst is, for the first time, applied for the effective production of biodiesel from fatty acids. Although vanadium phosphate has been extensively used in gas phase oxidation reactions, it has not drawn much attention for its application in liquid phase reactions. Our recent results indicate that vanadium phosphate is an effective, minimally polluting and re-usable catalyst that is highly suited to the production of biodiesel from fatty acids. This work extends the possibility of using VPO in other liquid phase reactions.

  17. The influence of calcium, magnesium, phosphorus and silica on vanadium precipitation in acidic sulfate solutions

    Directory of Open Access Journals (Sweden)

    A. H. Martins

    2000-06-01

    Full Text Available The experimental research work was carried out in accordance with the Factorial Design Statistical Method to evaluate and analyze the influence of calcium, magnesium, silica and phosphorus on the precipitation of vanadates. Precipitation was performed by neutralization with H2SO4 of alkaline aqueous solutions containing vanadium pentoxide (V2O5 at 60± 2ºC. The experimental responses measured were percent of vanadium recovery and vanadium pentoxide content in the precipitate. These impurities are considered representative of those present in a leach liquor from the ore obtained at Campo Alegre de Lourdes (Brazil. The operational variables in this work were used under optimum conditions as determined by the statistical approach. Among the impurities under study, phosphorus exhibited the highest negative influence on the experimental responses. Phosphorus diminished the percent of vanadium recovered from 98.9 to 34.5 and the vanadium oxide content in the precipitate from 91.2 % to 39.3 %.

  18. Can Vanadium Be Substituted into LiFePO[subscript 4]?

    Energy Technology Data Exchange (ETDEWEB)

    Omenya, Fredrick; Chernova, Natasha A.; Upreti, Shailesh; Zavalij, Peter Y.; Nam, Kyung-Wan; Yang, Xiao-Qing; Whittingham, M. Stanley (Binghamton); (BNL); (Maryland)

    2015-10-15

    Vanadium is shown to substitute for iron in the olivine LiFePO{sub 4} up to at least 10 mol %, when the synthesis is carried out at 550 C. In the solid solution LiFe{sub 1-3y/2}V{sub y}PO{sub 4}, the a and b lattice parameters and cell volume decrease with increasing vanadium content, while the c lattice parameter increases slightly. However, when the synthesis is performed at 650 C, a NASICON phase, Li{sub 3}V{sub 2}(PO{sub 4}){sub 3}, is also formed, showing that solid solution is a function of the synthesis temperature. X-ray absorption near-edge structure indicates vanadium is in the 3+ oxidation state and in an octahedral environment. Magnetic studies reveal a shift of the antiferromagnetic ordering transition toward lower temperatures with increasing vanadium substitution, confirming solid solution formation. The addition of vanadium enhances the electrochemical performance of the materials especially at high current densities.

  19. The role of vanadium haloperoxidases in the formation of volatile brominated compounds and their impact on the environment

    NARCIS (Netherlands)

    Wever, R.; van der Horst, M.A.

    2013-01-01

    Vanadium haloperoxidases differ strongly from heme peroxidases in substrate specificity and stability and in contrast to a heme group they contain the bare metal oxide vanadate as a prosthetic group. These enzymes specifically oxidize halides in the presence of hydrogen peroxide into hypohalous

  20. Development of analytical techniques of vanadium isotope in seawater

    Science.gov (United States)

    Huang, T.; Owens, J. D.; Sarafian, A.; Sen, I. S.; Huang, K. F.; Blusztajn, J.; Nielsen, S.

    2015-12-01

    Vanadium (V) is a transition metal with isotopes of 50V and 51V, and oxidation states of +2, +3, +4 and +5. The average concentration in seawater is 1.9 ppb, which results in a marine residence time of ~50 kyrs. Its various oxidation states make it a potential tool for investigating redox conditions in the ocean and sediments due to redox related changes in the valance state of vanadium. In turn, chemical equilibrium between different oxidation states of V will likely cause isotopic fractionation that can potentially be utilized to quantify past ocean redox states. In order to apply V isotopes as a paleo-redox tracer, it is required that we know the isotopic composition of seawater and the relation to marine sources and sinks of V. We developed a novel method for pre-concentrating V and measuring the isotope ratio in seawater samples. In our method, we used four ion exchange chromatography columns to separate vanadium from seawater matrix elements, in particular titanium and chromium, which both have an isobaric interference on 50V. The first column uses the NOBIAS resin, which effectively separates V and other transition metals from the majority of seawater matrix. Subsequent columns are identical to those utilized when separating V from silicate samples (Nielsen et al, Geostand. Geoanal. Res., 2011). The isotopic composition of the purified V is measured using a Thermo Scientific Neptune multiple collector inductively coupled plasma mass spectrometer (MC-ICP-MS) in medium resolution mode. This setup resolves all molecular interferences from masses 49, 50, 51, 52 and 53 including S-O species on mass 50. To test the new method, we spiked an open ocean seawater sample from the Bermuda Atlantic Time Series (BATS) station with 10-25 μg of Alfa Aesar vanadium solution, which has an isotopic composition of δ51V = 0 [where δ51V = 1000 × [(51V/50Vsample - 51V/50VAA)/51V/50VAA]. The average of six spiked samples is -0.03±0.19‰, which is within error of the true

  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. Electrochemical lithium intercalation into vanadium pentoxide xerogel film electrode

    Energy Technology Data Exchange (ETDEWEB)

    Pyun, Su Il; Bae, Joon Sung [Korea Advanced Inst. of Science and Technology, Daejon (Korea, Republic of). Dept. of Materials Science and Engineering

    1997-10-01

    The lithium-ion transport in vanadium pentoxide xerogel film electrodes has been investigated by using cyclic voltammetry and electrochemical impedance spectroscopy. The oxide xerogel film electrodes were prepared by spin-coating a viscous gel on an indium tin oxide (ITO) substrate. The spin-coated xerogel films were dried under vacuum at 130 and 270 C, respectively. The lithium intercalation into the xerogel film electrode dried at 270 C is limited by the interfacial reaction at the electrolyte/electrode interface rather than the lithium-ion transport in the oxide electrode. On the other hand, lithium intercalation into the film electrode dried at 130 C is largely limited by the lithium transport in the oxide film, and the chemical diffusivity of the lithium ion in the oxide film was determined to decrease from 10{sup -10} to 10{sup -12} cm{sup 2} s{sup -1} as the electrode potential of the oxide film fell from 3.0 to 2.2 V{sub Li/Li{sup +}}. The tranition of the diffusion-controlled intercalation to the interfacial reaction-controlled intercalation into the oxide xerogel film with decreasing drying temperature was explained in terms of the modification of the oxide lattice to a more open-structured lattice by structural modification of the oxide film by water molecules incorporated into the film. (orig.)

  3. Model investigations for vanadium-protein interactions: vanadium(III) compounds with dipeptides and their oxovanadium(IV) analogues.

    Science.gov (United States)

    Tasiopoulos, Anastasios J; Tolis, Evangelos J; Tsangaris, John M; Evangelou, Angelos; Woollins, DerekJ; Slawin, Alexandra M Z; Pessoa, Costa; Correia, Isabel; Kabanos, Themistoklis A

    2002-04-01

    The reaction of VCl(3) with 1,10-phenanthroline and a series of dipeptides (H(2)dip), having aliphatic as well as aromatic side chains, in methyl alcohol and in the presence of triethylamine affords vanadium(III) compounds of the general formula [V(III)(dip)(MeOH)(phen)]Cl. Aerial oxidation/hydrolysis of the vanadium(III) species gives their oxovanadium(IV) analogues of the general formula [V(IV)O(dip)(phen)]. X-ray crystallographic characterization of the [V(IV)O(dip)(phen)] compounds (where dip(2-)=Gly- L-Ala, Gly- L-Val and Gly- L-Phe) revealed that the vanadium atom possesses a severely distorted octahedral coordination and is ligated to a tridentate dip(2-) ligand at the N(amine) atom, the deprotonated N(peptide) atom and one of the O(carboxylate) atoms, as well as an oxo group and two phenanthroline nitrogen atoms. Circular dichroism characterization of the V(III)/V(IV)O(2+)-dipeptide compounds revealed a strong signal for the V(IV)O(2+) species in the visible range of the spectrum, with a characteristic pattern which may be exploited to identify the N(am), N(pep) and O(car) ligation of a peptide or a protein to V(IV)O(2+) center, and a weak Cotton effect of opposite sign to their vanadium(III) analogues. The visible spectra of the V(III)-dipeptide compounds revealed two d-d bands with high intensity, thus indicating that the covalency of the metal-donor atoms is significant, i.e. the vanadium d orbitals are significantly mixed with the ligand orbitals, and this is confirmed by the low values of their Racah B parameters. The high-intensity band of the V(IV)O(2+)-dipeptide compounds at approximately 460 nm implies also a strong covalency of the metal with the equatorial donor atoms and this was supported by the EPR spectra of these compounds. Moreover, the V(III)/V(IV)O(2+)-dipeptide complexes were characterized by EPR and IR spectroscopies as well as conductivity and magnetic susceptibility measurements.

  4. Mesoporous Vanadium Nitride Synthesized by Chemical Routes

    National Research Council Canada - National Science Library

    Mishra, Pragnya P; Theerthagiri, J; Panda, Rabi N

    2014-01-01

    Nanocrystalline vanadium nitride (VN) materials are synthesized by two different routes, namely, the urea route and the ammonia route, using various V2O5 precursors obtained by citric acid–based sol–gel method...

  5. Vertical Administration of Vanadium through Lactation Induces ...

    African Journals Online (AJOL)

    The work investigated the protective role of vitamin E on vanadium induced neurotoxicity. Three adult female rats were divided into three groups, A-C with each dam and her pups forming a group. Group A served as control. The dam in Group B was given 3mg/kg b.w./day of vanadium from PND 1 while the Group C dam ...

  6. Comparison of hypoglycemic activity and toxicity of vanadium (IV) and vanadium (V) absorbed in fermented mushroom of Coprinus comatus.

    Science.gov (United States)

    Ma, Zhaoji; Fu, Qin

    2009-12-01

    This study was designed to evaluate the effect and toxicity of administration of vanadium (IV, V) absorbed by Coprinus comatus (VACC) on alloxan-induced and sucrosefed hyperglycemic mice, respectively. The blood glucose, lipid profile, and the organ masses of the mice were analyzed. After the mice were administered with VACC, the blood glucose and the lipid profile of hyperglycemic mice decreased, irrespective of the VACC produced by vanadium (IV) or vanadium (V). However, the organ masses of the mice were significantly different after the mice were treated with vanadium (IV) and vanadium (V) 9 weeks later. The results indicate both vanadium (IV) and vanadium (V) absorbed in C. comatus have hypoglycemic activity on hyperglycemic mice. However, vanadium (IV) absorbed in C. comatus is less toxic to mice than vanadium (V).

  7. Vanadium speciation by chromatographic separation of V(IV) and V ...

    African Journals Online (AJOL)

    A new method for vanadium speciation has been developed. The method is based on chromatographic separation of vanadium(IV) and vanadium(V) in acidic medium followed by the determination with ICP-OES. Vanadium species exist in acidic solution (pH < 3) as VO2+ for vanadium(IV) and VO2 + for vanadium(V).

  8. 77 FR 46712 - Ferrovanadium and Nitrided Vanadium From the Russian Federation: Negative Final Determination of...

    Science.gov (United States)

    2012-08-06

    ... are vanadium additives other than ferrovanadium and nitrided vanadium, such as vanadium-aluminum master alloys, vanadium chemicals, vanadium waste and scrap, vanadium-bearing raw materials, such as slag... the processing performed in the United States represents a small proportion of the value of the...

  9. Vanadium in landscape components of western Transbaikalia

    Science.gov (United States)

    Kashin, V. K.

    2017-10-01

    Vanadium in soil-forming rocks, soils, and vegetation of forest-steppe, steppe, and dry-steppe landscapes of Transbaikalia has been studied. The mean element contents in rocks and soils are equal to its mean natural abundances (clarke values). The content of vanadium in soils is strictly determined by its content in parent materials; its dependence on the vanadium concentration in plants and on the soil pH and humus is less pronounced. With respect to the coefficient of biological uptake by plants, vanadium is assigned to the group of elements of slight accumulation (0.10-0.33) on mineral soils and of moderate accumulation (1.1-1.5) on peat bog soils. The mean vanadium concentration in steppe, meadow, and cultivated vegetation exceeds the norm for animals by 1.7-2.6 times but does not rich toxic levels. Vanadium uptake by plants is most intensive in meadow cenoses and is less intensive in dry-steppe cenoses.

  10. Protective effect of alpha glucosyl hesperidin (G-hesperidin) on chronic vanadium induced testicular toxicity and sperm nuclear DNA damage in male Sprague Dawley rats.

    Science.gov (United States)

    Vijaya Bharathi, B; Jaya Prakash, G; Krishna, K M; Ravi Krishna, C H; Sivanarayana, T; Madan, K; Rama Raju, G A; Annapurna, A

    2015-06-01

    The study was conducted to evaluate the vanadium-induced testicular toxicity and its effect on sperm parameters, sperm nuclear DNA damage and histological alterations in Sprague Dawley rats and to assess the protective effect of G-hesperidin against this damage. Treatment of rats with vanadium at a dose of 1 mg kg bw(-1) for 90 days resulted in significant reduction in serum testosterone levels, sperm count and motility. Further, a parallel increase in abnormal sperm morphology and adverse histopathological changes in testis was also associated with vanadium administration when compared to normal control. Moreover, sperm chromatin dispersion assay revealed that vanadium induces sperm nuclear DNA fragmentation. A marked increase in testicular malondialdehyde levels and decreased activity of antioxidant enzymes such as superoxide dismutase and catalase indicates vanadium-induced oxidative stress. Co-administration of G-hesperidin at a dose of 25 and 50 mg kg bw(-1) significantly attenuated the sperm parameters and histological changes by restoring the antioxidant levels in rat testis. These results suggested that vanadium exposure caused reduced bioavailability of androgens to the tissue and increased free radical formation, thereby causing structural and functional changes in spermatozoa. G-hesperidin exhibited antioxidant effect by protecting the rat testis against vanadium-induced oxidative damage, further ensures antioxidant potential of bioflavonoids. © 2014 Blackwell Verlag GmbH.

  11. Recovery of Vanadium from H2SO4-HF Acidic Leaching Solution of Black Shale by Solvent Extraction and Precipitation

    Directory of Open Access Journals (Sweden)

    Xingbin Li

    2016-03-01

    Full Text Available The recovery of vanadium from sulfuric and hydrofluoric mixed acid solutions generated by the direct leaching of black shale was investigated using solvent extraction and precipitation methods. The process consisted of reduction, solvent extraction, and stripping, followed by precipitation and calcination to yield vanadium pentoxide. The influence of various operating parameters on the extraction and recovery of vanadium was studied. Vanadium (IV was selectively extracted using a mixture of 10% (v/v di(2-ethylhexylphosphoric acid and 5% (v/v tri-n-butylphosphate in sulfonated kerosene. Using six extraction and five stripping stages, the extraction efficiency for vanadium was 96.7% and the stripping efficiency was 99.7%. V2O5 with a purity of 99.52% was obtained by oxidation of the loaded strip solution and precipitation of ammonium polyvanadate at pH 1.8 to 2.2, followed by calcination of the dried precipitate at 550 °C for 2 h. It was concluded that the combination of solvent extraction and precipitation is an efficient method for the recovery of vanadium from a multi-element leach solution generated from black shale.

  12. Bioaccumulation of Vanadium by Vanadium-Resistant Bacteria Isolated from the Intestine of Ascidia sydneiensis samea.

    Science.gov (United States)

    Romaidi; Ueki, Tatsuya

    2016-06-01

    Isolation of naturally occurring bacterial strains from metal-rich environments has gained popularity due to the growing need for bioremediation technologies. In this study, we found that the vanadium concentration in the intestine of the vanadium-rich ascidian Ascidia sydneiensis samea could reach 0.67 mM, and thus, we isolated vanadium-resistant bacteria from the intestinal contents and determined the ability of each bacterial strain to accumulate vanadium and other heavy metals. Nine strains of vanadium-resistant bacteria were successfully isolated, of which two strains, V-RA-4 and S-RA-6, accumulated vanadium at a higher rate than did the other strains. The maximum vanadium absorption by these bacteria was achieved at pH 3, and intracellular accumulation was the predominant mechanism. Each strain strongly accumulated copper and cobalt ions, but accumulation of nickel and molybdate ions was relatively low. These bacterial strains can be applied to protocols for bioremediation of vanadium and heavy metal toxicity.

  13. Thermodynamics and kinetics of reactions involving vanadium in natural systems: Accumulation of vanadium in sedimentary rocks

    Science.gov (United States)

    Wanty, R.B.; Goldhaber, M.B.

    1992-01-01

    A critical review of thermodynamic data for aqueous and solid V species is presented to evaluate dissolution, transport, and precipitation of V under natural conditions. Emphasis is given to results of experimental studies of V chemistry, especially those for which the experimental conditions are near those found in nature. Where possible, data are obtained for or corrected to the reference conditions of 298.15K, 1 atm (1.01325 bar) and zero ionic strength. Vanadium [IV] (VIV) and vanadium[V] (VV) are the most soluble forms of V in nature, and their complexes with fluoride, sulfate, and oxalate may act to increase V solubility under oxidizing conditions. Because redox behavior is of fundamental importance to understanding natural V chemistry, the kinetics of reduction of VIV to VIII H2S were studied. Although H2S is predicted from thermodynamic data to be capable of reducing VIV to VIII, this reaction has not been demonstrated experimentally. Experiments were carried out under conditions of temperature (45??C), pH (3.6-6.8), ionic strength (0.05-0.1 m), and V concentrations (9.8-240 ??molar) likely to be found in nature. Because the reaction is very slow, H2S concentrations in excess of natural conditions were used (8.1 ?? 10-4 to 0.41 atm). The results show that VIV is reduced to VIII under a variety of conditions. The rate increases with increasing pH, but is not appreciably affected by ionic strength (as represented by the concentration of KCl, which was used as the supporting electrolyte in all cases). Prior to initiation of the reaction, there is an induction period, the length of which increases with increasing KCl concentration or decreasing pH. Attempts to model the reaction mechanism by numerical methods have failed to produce a satisfying fit of the results, indicating partial reaction orders, a complex mechanism, or involvement of a variety of intermediate species. The results of the thermodynamic and kinetic studies were applied to understanding the

  14. Influence of titanium and vanadium on the hydrogen transport through amorphous alumina films

    Energy Technology Data Exchange (ETDEWEB)

    Palsson, G.K. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Wang, Y.T. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Azofeifa, D. [Centro de Investigacion en Ciencia e Ingenieria de Materiales and Escuela de Fisica, Universidad de Costa Rica, San Jose (Costa Rica); Raanaei, H. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Department of Physics, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of); Sahlberg, M. [Department of Materials Chemistry, Uppsala University, Box 538, S-751 21 Uppsala (Sweden); Hjoervarsson, B. [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden)

    2010-04-02

    The influence of titanium and vanadium on the hydrogen transport rate through thin amorphous alumina films is addressed. Only small changes in the transport rate are observed when the Al{sub 2}O{sub 3} are covered with titanium or vanadium. This is in stark contrast to results with a Pd overlayer, which enhances the transport by an order of magnitude. Similarly, when titanium is embedded into the alumina the transport rate is faster than for the covered case but still slower than the undoped reference. Embedding vanadium in the alumina does not yield an increase in uptake rate compared to the vanadium covered oxide layers. These results add to the understanding of the hydrogen uptake of oxidized metals, especially the alanates, where the addition of titanium has been found to significantly enhance the rate of hydrogen uptake. The current findings eliminate two possible routes for the catalysis of alanates by Ti, namely dissociation and effective diffusion short-cuts formed by Ti. Finally, no photocatalytic enhancement was noticed on the titanium covered samples.

  15. An extraction-chromogenic system for vanadium(IV,V based on 2,3-dihydroxynaphtahlene

    Directory of Open Access Journals (Sweden)

    Gavazov Kiril B.

    2016-10-01

    Full Text Available A liquid-liquid extraction-chromogenic system for vanadium(IV, V containing 2,3-dihydroxynaphtahlene (DN, 2,3,5-triphenyl-2H-tetrazolium chloride (TTC, water and chloroform was studied in detail. When the vanadium is in the oxidation state of IV, the extracted species are aggregates containing three 1:2:1 (V:DN:TTC ion-pair units composed of triphenyltetrazolium cations (TT+ and chelate anions {[VIVO(DN(DNH]− (I and/or [VIV(OH(DN2]− (II}. When the initial oxidation state of vanadium is V and the DN concentration is high, vanadium(V is reduced by DN to a lower oxidation state, V(IV. However, at low DN concentration, vanadium(V can enter the organic phase as a part of an ion-pair consisting of TT+ and [VVO2(DN]− (III. The ground-state equilibrium geometries of the anions I, II, and III were optimized by quantum chemical calculations using BLYP/6-31++G⋆. The following characteristics were determined under the optimum conditions for VIV extraction: absorption maximum λmax = 333 nm, molar absorptivity ε333= 2.1x104 dm3 mol−1 cm−1, Sandell’s sensitivity SS = 2.4 ng cm−2, and fraction extracted E = 98%. The conditional extraction constant was calculated by two independent methods. The calibration graph was linear in the range 0.1-3.1 μg cm−3 (R2=0.9994 and the limit of detection was 0.03 μg cm−3.

  16. In situ electrical resistivity measurements of vanadium thin films performed in vacuum during different annealing cycles

    Science.gov (United States)

    Pedrosa, Paulo; Cote, Jean-Marc; Martin, Nicolas; Arab Pour Yazdi, Mohammad; Billard, Alain

    2017-02-01

    The present study describes a sputtering and in situ vacuum electrical resistivity setup that allows a more efficient sputtering-oxidation coupling process for the fabrication of oxide compounds like vanadium dioxide, VO2. After the sputtering deposition of pure V thin films, the proposed setup enables the sample holder to be transferred from the sputtering to the in situ annealing + resistivity chamber without venting the whole system. The thermal oxidation of the V films was studied by implementing two different temperature cycles up to 550 °C, both in air (using a different resistivity setup) and vacuum conditions. Main results show that the proposed system is able to accurately follow the different temperature setpoints, presenting clean and low-noise resistivity curves. Furthermore, it is possible to identify the formation of different vanadium oxide phases in air, taking into account the distinct temperature cycles used. The metallic-like electrical properties of the annealed coatings are maintained in vacuum whereas those heated in air produce a vanadium oxide phase mixture.

  17. Iron diminishes the in vitro biological effect of vanadium.

    Science.gov (United States)

    Mechanistic pathways underlying inflammatory injury following exposures to vanadium-containing compounds are not defined. We tested the postulate that the in vitro biological effect of vanadium results from its impact on iron homeostasis. Human bronchial epithelial (HBE) cells ex...

  18. [An in vitro study on toxic effect of vanadium-titanium-magnetite dust on alveolar macrophage in rabbits].

    Science.gov (United States)

    Song, Y; Chen, Q; Guan, Y

    1998-11-01

    To study the toxic effect of vanadium-titanium-magnetite (VTM) dust on alveolar macrophage (AM) and its hazardous extent. Survival rates, morphology and function of AM were compared in rabbits exposed to dust of VTM, vanadium oxide, titanium dioxide and silica in various doses and length of time with in vitro cell culture and putamen membrane cover glass transmission electron microscopy, and changes in activities of lactic dehydrogenase (LDH) and acid phosphatase (ACP) in cell culture were measured. Exposure to all the four kinds of dust could lead to decrease in survival rate of AM, increase in activities of LDH and ACP in the cell culture, and changes in their morphology and function to the extent dependent on the nature of dust. Toxic effect of exposure to VTM dust was lower than that to vanadium oxide and silica, but higher than that to titanium dioxide, which had slight toxic effect.

  19. 77 FR 51825 - Ferrovanadium and Nitrided Vanadium From Russia

    Science.gov (United States)

    2012-08-27

    ... COMMISSION Ferrovanadium and Nitrided Vanadium From Russia Determination On the basis of the record \\1... antidumping duty order on ferrovanadium and nitrided vanadium from Russia would not be likely to lead to... contained in USITC Publication 4345 (August 2012), entitled Ferrovanadium and Nitrided Vanadium from Russia...

  20. Memory Deficit Recovery after Chronic Vanadium Exposure in Mice

    Directory of Open Access Journals (Sweden)

    Oluwabusayo Folarin

    2016-01-01

    Full Text Available Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Animals were tested using Morris water maze and forelimb grip test at 3, 6, 9, and 12 months of age. The results showed that animals across the groups showed no difference in learning but had significant loss in memory abilities after 3 months of vanadium exposure and this trend continued in all vanadium-exposed groups relative to the controls. Animals exposed to vanadium for three months recovered significantly only 9 months after vanadium withdrawal. There was no significant difference in latency to fall in the forelimb grip test between vanadium-exposed groups and the controls in all age groups. In conclusion, we have shown that chronic administration of vanadium in mice leads to memory deficit which is reversible but only after a long period of vanadium withdrawal.

  1. Determination of Leachable Vanadium (V) in Sediment | Mampuru ...

    African Journals Online (AJOL)

    A method for speciation of vanadium in solid samples was developed for quantification of vanadium(+5) in solid samples of sediment Certified Reference Materials (CRM) PACS-2 and MESS-3 (Trace Elements in Sediments) of known total vanadium content. The method relies on a classical analytical chemistry procedure ...

  2. Memory Deficit Recovery after Chronic Vanadium Exposure in Mice.

    Science.gov (United States)

    Folarin, Oluwabusayo; Olopade, Funmilayo; Onwuka, Silas; Olopade, James

    2016-01-01

    Vanadium is a transitional metal with an ability to generate reactive oxygen species in the biological system. This work was designed to assess memory deficits in mice chronically exposed to vanadium. A total of 132 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three major groups of vanadium treated, matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Animals were tested using Morris water maze and forelimb grip test at 3, 6, 9, and 12 months of age. The results showed that animals across the groups showed no difference in learning but had significant loss in memory abilities after 3 months of vanadium exposure and this trend continued in all vanadium-exposed groups relative to the controls. Animals exposed to vanadium for three months recovered significantly only 9 months after vanadium withdrawal. There was no significant difference in latency to fall in the forelimb grip test between vanadium-exposed groups and the controls in all age groups. In conclusion, we have shown that chronic administration of vanadium in mice leads to memory deficit which is reversible but only after a long period of vanadium withdrawal.

  3. Simple Sensitive Spectrophotometric Determination of Vanadium in Biological and Environmental Samples

    Directory of Open Access Journals (Sweden)

    B. Krishna Priya

    2006-01-01

    Full Text Available Novel, rapid, highly sensitive and selective spectrophotometric method for the determination of traces of vanadium (V in environmental and biological samples, pharmaceutical and steel samples was studied. The method is based on oxidation of 2,4- dinitro phenyl hydrazine(2,4-DNPH by vanadium (V followed by coupling reaction with N-(1-naphthalene-1-ylethane-1,2-diamine-dihydrochloride (NEDA in acidic medium to give red colored derivative or on oxidation of 4-Amino Pyridine by vanadium (V followed by coupling reaction with NEDA in basic medium to give pink colored derivative. The red colored derivative having an λmax 495 nm which is stable for 8 days and the pink colored derivative with 525 nm is stable for more than 7 days at 350C. Beer's law is obeyed for vanadium (V in the concentration range of 0.02 - 3.5 μg mL–1 (red derivative and 0.03 – 4.5 μg mL–1 (pink derivative at the wave length of maximum absorption. The optimum reaction conditions and other analytical parameters were investigated to enhance the sensitivity of the present method. The detailed study of various interferences made the method more selective. The proposed method was successfully applied to the analysis of vanadium in natural water samples, plant material, soil samples, synthetic mixtures, pharmaceutical samples and biological samples. The results obtained were agreed with the reported methods at the 95 % confidence level. The performance of proposed method was evaluated in terms of Student's t-test and Variance ratio f-test which indicates the significance of proposed method over reported method.

  4. Atomic layer deposition of VO{sub 2} films with Tetrakis-dimethyl-amino vanadium (IV) as vanadium precursor

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Xinrui [Key Laboratory of Inorganic Coating Materials CAS, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Cao, Yunzhen, E-mail: yzhcao@mail.sic.ac.cn [Key Laboratory of Inorganic Coating Materials CAS, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China); Yan, Lu; Li, Ying; Song, Lixin [Key Laboratory of Inorganic Coating Materials CAS, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2017-02-28

    Highlights: • VO{sub 2} film was easily deposited by ALD using novel vanadium precursor V(NMe{sub 2}){sub 4}. • Deposition and annealing condition were systematically investigated. • Comparable transition properties of VO{sub 2} film on resistance and spectral transmittance were studied. - Abstract: VO{sub 2} thin films have been grown on Si(100) (VO{sub 2}/Si) and fused silica substrates (VO{sub 2}/SiO{sub 2}) by atomic layer deposition (ALD) using tetrakis-dimethyl-amino vanadium (IV) (TDMAV) as a novel vanadium precursor and water as reactant gas. The quartz crystal microbalance (QCM) measurement was performed to study the ALD process of VO{sub 2} thin film deposition, and a constant growth rate of about 0.95 Å/cycle was obtained at the temperature range of 150–200 °C. XRD measurement was performed to study the influence of deposition temperature and post-annealing condition on the crystallization of VO{sub 2} films, which indicated that the films deposited between 150 and 200 °C showed well crystallinity after annealing at 475 °C for 100 min in Ar atmosphere. XPS measurement verified that the vanadium oxidation state was 4+ for both as-deposited film and post-annealed VO{sub 2}/Si film. AFM was applied to study the surface morphology of VO{sub 2}/Si films, which showed a dense polycrystalline film with roughness of about 1 nm. The resistance of VO{sub 2}/Si films deposited between 150 °C and 200 °C as a function of temperature showed similar semiconductor-to-metal transition (SMT) characters with the transition temperature for heating branch (T{sub c,h}) of about 72 °C, a hysteresis width of about 10 °C and the resistance change of two orders of magnitude. The increase of T{sub c,h} compared with the bulk VO{sub 2} (68 °C) may be attributed to the tensile stress along the c-axis in the film. Transmittance measurement of VO{sub 2}/SiO{sub 2} films showed typical thermochromic property with a NIR switching efficiency of above 50% at 2 μm across

  5. Characterization of vanadium bromoperoxidase from Macrocystis and Fucus: reactivity of vanadium bromoperoxidase toward acyl and alkyl peroxides and bromination of amines.

    Science.gov (United States)

    Soedjak, H S; Butler, A

    1990-08-28

    Vanadium bromoperoxidase (V-BrPO) has been isolated and purified from the marine brown algae Fucus distichus and Macrocystis pyrifera. V-BrPO catalyzes the oxidation of bromide by hydrogen peroxide, resulting in the bromination of certain organic acceptors or the formation of dioxygen. V-BrPO from F. distichus and M. pyrifera have subunit molecular weights of 65,000 and 74,000, respectively, and specific activities of 1580 units/mg (pH 6.5) and 1730 units/mg (pH 6) for the bromination of monochlorodimedone, respectively. As isolated, the enzymes contain a substoichiometric vanadium/subunit ratio; the vanadium content and specific activity are increased by addition of vanadate. V-BrPO (F. distichus, M. pyrifera, and Ascophyllum nodosum) also catalyzes the oxidation of bromide using peracetic acid. In the absence of an organic acceptor, a mixture of oxidized bromine species (e.g., hypobromous acid, bromine, and tribromide) is formed. Bromamine derivatives are formed from the corresponding amines, while 5-bromocytosine is formed from cytosine. In all cases, the rate of the V-BrPO-catalyzed reaction is much faster than that of the uncatalyzed oxidation of bromide by peracetic acid, at pH 8.5, 1 mM bromide, and 2 mM peracetic acid. In contrast to hydrogen peroxide, V-BrPO does not catalyze formation of dioxygen from peracetic acid in either the presence or absence of bromide. V-BrPO also uses phenylperacetic acid, m-chloroperoxybenzoic acid, and p-nitroperoxybenzoic acid to catalyze the oxidation of bromide; dioxygen is not formed with these peracids. V-BrPO does not catalyze bromide oxidation or dioxygen formation with the alkyl peroxides ethyl hydroperoxide, tert-butyl hydroperoxide, and cuminyl hydroperoxide.

  6. Impedance spectroscopy study and phase transition in phospho-vanadium mixed oxide LiZnV{sub 0.5}P{sub 0.5}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Rahal, A.; Guidara, Kamel; Megdiche, Makram [Sfax Universite, Laboratoire de Caracterisations Spectroscopiques et Optique des Materiaux (LaSCOM), Faculte des Sciences de Sfax, BP 1171, Sfax (Tunisia); Megdiche Borchani, S. [Sfax Universite, Laboratoire de Caracterisations Spectroscopiques et Optique des Materiaux (LaSCOM), Faculte des Sciences de Sfax, BP 1171, Sfax (Tunisia); Institut Superieur D' Informatique et de Multimedia de Sfax (ISIMS), Pole Technologique de Sfax, Sakiet Ezzit, BP 242, Sfax (Tunisia)

    2017-08-15

    An X-ray crystallographic study has allowed us to identify a powder of the type LiZnV{sub 0.5}P{sub 0.5}O{sub 4}, which contains 50% of vanadium and 50% of phosphor, inside the binary system LiZnVO{sub 4}-LiZnPO{sub 4}. The structure is isotypic with the phenacite like LiZnP0{sub 4}. X-ray diffraction patterns are indexed according to the lattice parameters of the rhombohedral system and the R3 space group. IR spectra show the presence of VO{sub 4} and PO{sub 4} groups in the network of this material. The experimental results indicate that σ{sub AC}(ω) is proportional to (ω{sup n}). The activation energy found from the Arrhenius plot confirms that the conduction processing of the material is not due to simple hopping mechanism. The temperature dependence of frequency exponent n was investigated to understanding the conduction mechanism in LiZnV{sub 0.5}P{sub 0.5}O{sub 4}. The non-overlapping small Polaron tunneling (NSPT) model can explain the temperature dependence of the frequency exponent. A phase transition at T = 623 K has been evidenced by Differential scanning calorimetry (DSC) and subsequently confirmed by the analysis of dielectric and electric properties. (orig.)

  7. Global biogeochemical cycle of vanadium.

    Science.gov (United States)

    Schlesinger, William H; Klein, Emily M; Vengosh, Avner

    2017-12-26

    Synthesizing published data, we provide a quantitative summary of the global biogeochemical cycle of vanadium (V), including both human-derived and natural fluxes. Through mining of V ores (130 × 109 g V/y) and extraction and combustion of fossil fuels (600 × 109 g V/y), humans are the predominant force in the geochemical cycle of V at Earth's surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric flux probably derives from emissions from the combustion of fossil fuels, but the magnitude of this flux depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the flux of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced-with about 40 × 109 g V/y to 50 × 109 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers.

  8. Vanadium bioavailability in soils amended with blast furnace slag

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Maja A., E-mail: maja.larsson@slu.se [Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala (Sweden); Baken, Stijn, E-mail: stijn.baken@ees.kuleuven.be [Department of Earth and Environmental Sciences, Leuven University, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven (Belgium); Smolders, Erik, E-mail: erik.smolders@ees.kuleuven.be [Department of Earth and Environmental Sciences, Leuven University, Kasteelpark Arenberg 20 bus 2459, 3001 Leuven (Belgium); Cubadda, Francesco, E-mail: francesco.cubadda@iss.it [Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, Rome 00161 (Italy); Gustafsson, Jon Petter, E-mail: jon-petter.gustafsson@slu.se [Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, 750 07 Uppsala (Sweden); Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, Brinellvägen 28, 100 44 Stockholm (Sweden)

    2015-10-15

    Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800 mg V kg{sup −1}) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment.

  9. Partial Oxidation of n-Pentane over Vanadium Phosphorus Oxide ...

    African Journals Online (AJOL)

    NICOLAAS

    hydrocarbons using heterogeneous catalysts to produce these compounds ... catalysts produced dehydrogenated products. Here ... vation of n-pentane using V2O5 supported on hydroxyapatite as catalysts. V2O5 showed excellent redox capabilities. Selectivity towards the anhydrides (MA 40 % and PA 25 %) was obtained.

  10. The Effect of Chromium on the Roasting Process of Vanadium Extraction

    Directory of Open Access Journals (Sweden)

    Dong Liu

    2016-07-01

    Full Text Available We simulated the roasting process of chromium by mixing Cr2O3 and Na2CO3 to analyze the influence of chromium on roasting vanadium slag. Samples were characterized by XRD, thermal analysis and SEM at different temperatures: Cr2O3 and Na2CO3 began to react at 500 °C. When the chromium oxide content was about 3.2%, the conversion rate of V reached the maximum value of 95%.

  11. The Role of Vanadium Bromoperoxidase in the Biosynthesis of Halogenated Marine Natural Products

    OpenAIRE

    Franklin, Jayme N.

    2003-01-01

    The widespread occurrence of bromine- and chlorine-containing marine natural products has prompted investigations into the biosynthesis of halogenated marine metabolites. Halogenating enzymes, such as haloperoxidases, have long been thought to be involved in the biogenesis of halogenated marine natural products. Vanadium bromoperoxidases (V-BrPO) have been identified and isolated from all major classes of marine algae, and catalyze the two-electron oxidation of bromide by hydrogen peroxide. ...

  12. Comparison of silica-supported MoO{sub 3} and V{sub 2}O{sub 5} catalysts in the selective partial oxidation of methane

    Energy Technology Data Exchange (ETDEWEB)

    Faraldos, M.; Banares, M.A.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica, Madrid (Spain)] [and others

    1996-05-01

    The catalytic effects of molybdenum oxide and vanadium oxide catalysts supported on silica have been investigated for a wide range of metal loadings in the selective oxidation of methane. Vanadium oxide catalysts tend to be more active, but produce less formaldehyde. 49 refs., 7 figs.

  13. Vanadium in marine mussels and algae.

    Science.gov (United States)

    Sperling, K R; Bahr, B; Ott, J

    2000-01-01

    A method is presented which is sensitive enough for the determination of vanadium (V) in marine organisms such as mussels and algae. It was sufficiently checked by a reference material and it was applied to V determination in blue mussels and brown algae from the German Bight.

  14. Geochemistry of vanadium (V) in Chinese coals.

    Science.gov (United States)

    Liu, Yuan; Liu, Guijian; Qu, Qinyuan; Qi, Cuicui; Sun, Ruoyu; Liu, Houqi

    2017-10-01

    Vanadium in coals may have potential environmental and economic impacts. However, comprehensive knowledge of the geochemistry of V in coals is lacking. In this study, abundances, distribution and modes of occurrence of V are reviewed by compiling >2900 reported Chinese coal samples. With coal reserves in individual provinces as the weighting factors, V in Chinese coals is estimated to have an average abundance of 35.81 μg/g. Large variation of V concentration is observed in Chinese coals of different regions, coal-forming periods, and maturation ranks. According to the concentration coefficient of V in coals from individual provinces, three regions are divided across Chinese coal deposits. Vanadium in Chinese coals is probably influenced by sediment source and sedimentary environment, supplemented by late-stage hydrothermal fluids. Specifically, hydrothermal fluids have relatively more significant effect on the enrichment of V in local coal seams. Vanadium in coals is commonly associated with aluminosilicate minerals and organic matter, and the modes of V occurrence in coal depend on coal-forming environment and coal rank. The Chinese V emission inventory during coal combustion is estimated to be 4906 mt in 2014, accounting for 50.55 % of global emission. Vanadium emissions by electric power plants are the largest contributor.

  15. Temperature dependence of thermal conductivity of vanadium ...

    Indian Academy of Sciences (India)

    Unknown

    . Cryogenic Engineering .... Thermal conductivity of vanadium substituted BPSCCO system. 441 trical resistivity as well as the small decrease ..... G, Marre D, Putti M and Siri A S 1997 Physica C273 314. Chawlek J M, Uher C, Whitaker J F and ...

  16. Role of vanadium in Bi-2223 ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 54; Issue 2. Role of vanadium in Bi-2223 ceramics. D R Mishra ... higher magnetization scattering at the Cu site. The results were explained keeping in mind the liquid phase mechanism behind the formation of the 2223 phase and the possibility of magnetic scattering.

  17. An improved method of preparation of nanoparticular metal oxide catalysts

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns an improved method of preparation of nanoparticular vanadium oxide/anatase titania catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular vanadium oxide/anatase titania catalyst precursors comprising...... combustible crystallization seeds upon which the catalyst metal oxide is coprecipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step....

  18. Electrochemistry of vanadium(II and the electrodeposition of aluminum-vanadium alloys in the aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt

    Directory of Open Access Journals (Sweden)

    Tsuda T.

    2003-01-01

    Full Text Available The electrochemical behavior of vanadium(II was examined in the 66.7-33.3 mole percent aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt containing dissolved VCl2 at 353 K. Voltammetry experiments revealed that V(II could be electrochemically oxidized to V(III and V(IV. However at slow scan rates the V(II/V(III electrode reaction is complicated by the rapid precipitation of V(III as VCl3. The reduction of V(II occurs at potentials considerably negative of the Al(III/Al electrode reaction, and Al-V alloys cannot be electrodeposited from this melt. However electrodeposition experiments conducted in VCl2-saturated melt containing the additive, 1-ethyl-3-methylimidazolium tetrafluoroborate, resulted in Al-V alloys. The vanadium content of these alloys increased with increasing cathodic current density or more negative applied potentials. X-ray analysis of Al-V alloys that were electrodeposited on a rotating copper wire substrate indicated that these alloys did not form or contain an intermetallic compound, but were non-equilibrium or metastable solid solutions. The chloride-pitting corrosion properties of these alloys were examined in aqueous NaCl by using potentiodynamic polarization techniques. Alloys containing ~10 a/o vanadium exhibited a pitting potential that was 0.3 V positive of that for pure aluminum.

  19. Speciation of vanadium in Chinese cabbage (Brassica rapa L.) and soils in response to different levels of vanadium in soils and cabbage growth.

    Science.gov (United States)

    Tian, Liyan; Yang, Jinyan; Alewell, Christine; Huang, Jen-How

    2014-09-01

    This study highlights the accumulation and speciation of vanadium in Chinese cabbage (Brassica rapa L.) in relation to the speciation of soil vanadium with pot experiments at 122-622mgVkg(-1) by spiking NH4VO3. Cabbage planting decreased the bioavailable and residual vanadium based on sequential extraction, leading to enrichment of oxalate-extractable vanadium in soils. The biomass production increased with increasing concentrations of soil vanadium from 122 to 372mgVkg(-1), probably due to the increasing nitrogen availability and low vanadium availability in our soils with a consequent low vanadium toxicity. Although the concentrations of root vanadium (14.4-24.9mgVkg(-1)) related positively with soil vanadium, the bio-dilution alleviated the increase of leaf vanadium (2.1-2.7mgVkg(-1)). The predominance of vanadium(IV) in leaves (∼60-80% of total vanadium) indicates bio-reduction of vanadium in Chinese cabbage, since the mobile vanadium in oxic soils was usually pentavalent. Approximately 15-20% of the leaf vanadium was associated with recalcitrant leaf tissues. The majority of leaf vanadium was water and ethanol extractable, which is considered mobile and may cause more toxic effects on Chinese cabbage. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Geochemistry and mineralogy of vanadium in mine tailings at Berg Aukas, northeastern Namibia

    Science.gov (United States)

    Sracek, O.; Mihaljevič, M.; Kříbek, B.; Majer, V.; Filip, J.; Vaněk, A.; Penížek, V.; Ettler, V.; Mapani, B.

    2014-08-01

    Vanadium-rich mine tailings at Berg Aukas, site with a world-known vanadium mineralization in northeastern Namibia, were investigated using a combination of solid phase and mineralogical analyses, leaching tests and speciation modeling. Principal objective of the study was to determine, if vanadium can be released into the environment. In spite of >30 y of weathering and oxidation of tailings material to a maximum sampling depth of 2.4 m, a large portion of V still remains in the primary mineral descloizite, (Pb, Zn)2(OH)VO4. A part of V was mobilized and adsorbed/co-precipitated with ferric oxyhydroxides. Based on sequential extraction and 57Fe Mössbauer spectroscopy, a large amount of ferric iron is present in insoluble hematite and goethite, where V is effectively bound. Other potential contaminants are Zn, present mostly in the primary mineral willemite, Zn2SiO4, descloizite and also in secondary smithsonite, ZnCO3; and Pb, which was transferred from completely dissolved galena to cerussite, PbCO3 and is also partly present in primary descloizite. Conditions in the mine tailings are alkaline (pH generally >8.2) and oxidizing during dry period, but mobility of V is low due to low solubility of descloizite and secondary crystalline ferric phases such as hematite. In contrast, Zn and especially Pb in secondary carbonates, probably represent more serious environmental and health risks.

  1. Optimal Location of Vanadium in Muscovite and Its Geometrical and Electronic Properties by DFT Calculation

    OpenAIRE

    Qiushi Zheng; Yimin Zhang; Tao Liu; Jing Huang; Nannan Xue; Qihua Shi

    2017-01-01

    Vanadium-bearing muscovite is the most valuable component of stone coal, which is a unique source of vanadium manufacture in China. Numbers of experimental studies have been carried out to destroy the carrier muscovite’s structure for efficient extraction of vanadium. Hence, the vanadium location is necessary for exploring the essence of vanadium extraction. Although most infer that vanadium may substitute for trivalent aluminium (Al) as the isomorphism in muscovite for the similar atomic rad...

  2. Extraction of Vanadium from Vanadium Slag Via Non-salt Roasting and Ammonium Oxalate Leaching

    Science.gov (United States)

    Li, Meng; Du, Hao; Zheng, Shili; Wang, Shaona; Zhang, Yang; Liu, Biao; Dreisinger, David Bruce; Zhang, Yi

    2017-10-01

    A clean method featuring non-salt roasting followed by (NH4)2C2O4 leaching to recover vanadium from vanadium slag was proposed. The carcinogenic Cr6+ compounds and exhaust gases were avoided, and the water generated from vanadate precipitation may be recycled and reused in this new leaching process. The leaching residues may be easily used by a blast furnace. Moreover, (NH4)2C2O4 solution was used as a leaching medium to avoid expensive and complicated ammonium controlling operations as a result of the stability of (NH4)2C2O4 at a high temperature. The transformation mechanisms of vanadium- and chromium-bearing phases were systematically investigated by x-ray diffraction analysis and scanning electron microscopy with energy-disperse x-ray spectrometry, respectively. In addition, the effects of oxygen concentration, roasting temperature, and holding time on vanadium recovery were investigated. Finally, the effects of leaching variables on the vanadium leaching rate were also examined.

  3. Discrepancy between theory and measurement of superconducting vanadium

    Science.gov (United States)

    Zheng, X. H.; Walmsley, D. G.

    2015-08-01

    We have extracted consistent phonon dispersion information out of rather inconsistent vanadium X-ray scattering data from synchrotron and vacuum tube sources. With this and a new theoretical approach we have made firm predictions for the tunnelling conductance of superconducting vanadium; it is in unusually poor agreement with experimentally measured values. We argue that the problem lies in the experimental measurement rather than the theory. The preparation of a suitable high quality tunnel barrier on vanadium represents an outstanding challenge.

  4. Chemical speciation of vanadium in coal bottom Ash

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Firat; Aydin, Isil; Hamamci, Candan [Science Faculty, Chemistry Department, Dicle University, Diyarbakir (Turkey); Saydut, Abdurrahman [Engineering Faculty, Mining Engineering Department, Dicle University, Diyarbakir (Turkey); Gunduz, Beniz [Science Faculty, Chemistry Department, Selcuk University, Konya (Turkey)

    2012-04-15

    Chemical speciation of vanadium is important to understand the true nature of this element in the environment as well as its biochemical pathways. Sample pretreatment, preparation, and chemical speciation methods were applied for vanadium in coal bottom ash here. Two-stage microwave acid digestion was used to preparation of samples. Determination of vanadium was performed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Speciation of vanadium was carried out using a seven-step sequential extraction procedure of the coal bottom ash each releasing species of vanadium: Water soluble, exchangeable, carbonate, reducible, oxidizable, sulfide, and residual fractions. Total vanadium concentration in the coal bottom ash is 701 mg kg{sup -1} d.w. The most abundant form of vanadium in coal bottom ash is residual fraction of vanadium (196 mg kg{sup -1} d.w.). Relative abundances of the remaining vanadium fractions in coal bottom ash are as follows: Reducible (176 mg kg{sup -1} d.w.) > sulfide (176 mg kg{sup -1} d.w.) > carbonate (85 mg kg{sup -1} d.w.) > oxidizable (50 mg kg{sup -1} d.w.) > water soluble (10.6 mg kg{sup -1} d.w.) > exchangeable (9.0 mg kg{sup -1} d.w.). (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Microadditions of boron and vanadium in ADI

    Directory of Open Access Journals (Sweden)

    Rzychoń T.

    2007-01-01

    Full Text Available In the second part of the study, describing the role of vanadium and boron microadditions in the process of structure formation in heavy-walled castings made from ADI, the results of own investigations were presented. Within this study two series of melts of the ductile iron were made, introducing microadditions of the above mentioned elements to both unalloyed ductile iron and the ductile iron containing high levels of nickel and copper (the composition typical of ADI. Melts were conducted with iron-nickel-magnesium master alloy. Thermal analysis of the solidification process of the cast keel blocks was conducted, the heat treatment of the alloys was carried out, and then the effect of the introduced additions of boron and vanadium on the hardenability of the investigated cast iron was examined and evaluated.

  6. Vanadium in fuel oil - a new solution

    Energy Technology Data Exchange (ETDEWEB)

    Czech, N. [Siemens, Muelheim (Germany); Finckh, H. [Siemens, Erlangen (Germany)

    1998-11-01

    Hot corrosion of the hot-gas-path components due to vanadium contamination is one of the hazards associated with heavy residual oil combustion in heavy-duty gas turbines. This economically attractive oil combustion process has benefited from the recently developed vanadium inhibition technique, which is currently being tested at the Valladolid 220 MWe combined cycle plant in Mexico. The method uses atomization of a dilute aqueous solution of Epsom salt (MgSO{sub 7},7H{sub 2}O) into very small droplets which are then injected onto the flame where intensive mixing takes place. The successful use of this new technique promises extended operating periods between cleanup operations, and cost reductions from the use of inexpensive materials, as well as the ability to operate advanced gas turbines on difficult fuels, not previously feasible. (UK)

  7. Irradiation creep of vanadium-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, H.; Billone, M.C.; Strain, R.V.; Smith, D.L. [Argonne National Lab., IL (United States); Matsui, H. [Tohoku Univ. (Japan)

    1998-03-01

    A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the United States. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200--300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from {approx}0 to 1.2 {times} 10{sup {minus}5}/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence.

  8. Hazardous waste to materials: recovery of molybdenum and vanadium from acidic leach liquor of spent hydroprocessing catalyst using alamine 308.

    Science.gov (United States)

    Sahu, K K; Agrawal, Archana; Mishra, D

    2013-08-15

    Recovery of valuable materials/metals from waste goes hand in hand with environmental protection. This paper deals with the development of a process for the recovery of metals such as Mo, V, Ni, Al from spent hydroprocessing catalyst which may otherwise cause a nuisance if dumped untreated. A detailed study on the separation of molybdenum and vanadium from the leach solution of spent hydroprocessing catalyst of composition: 27.15% MoO₃, 1.7% V₂O₅, 3.75% NiO, 54.3% Al₂O₃, 2.3% SiO₂ and 10.4% LOI is reported in this paper. The catalyst was subjected to roasting under oxidizing atmosphere at a temperature of about 550 °C and leaching in dilute sulphuric acid to dissolve molybdenum, vanadium, nickel and part of aluminium. Metals from the leach solution were separated by solvent extraction. Both molybdenum and vanadium were selectively extracted with a suitable organic solvent leaving nickel and dissolved aluminium in the raffinate. Various parameters such as initial pH of the aqueous feed, organic to aqueous ratio (O:A), solvent concentration etc. were optimized for the complete extraction and recovery of Mo and V. Molybdenum and vanadium from the loaded organic were stripped by ammonia solution. They were recovered as their corresponding ammonium salt by selective precipitation, and were further calcined to get the corresponding oxides in pure form. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Microadditions of boron and vanadium in ADI

    OpenAIRE

    Rzychoń T.; Kiełbus A.; Szala J.

    2007-01-01

    In the second part of the study, describing the role of vanadium and boron microadditions in the process of structure formation in heavy-walled castings made from ADI, the results of own investigations were presented. Within this study two series of melts of the ductile iron were made, introducing microadditions of the above mentioned elements to both unalloyed ductile iron and the ductile iron containing high levels of nickel and copper (the composition typical of ADI). Melts were conducted ...

  10. Determination of Leachable Vanadium (V) in Sediment

    African Journals Online (AJOL)

    NICO

    USA) were used for the filtration of sample solutions. RESEARCH ... were transferred to a Teflon beaker and treated on a hot plate at about 110 °C ... Table 1 Thermal programme for the determination of vanadium using. ET-AAS. Step. Temperature/°C. Ramp/s–1. Hold/s–1. Internal gas flow/mL min–1. 1. 120. 1. 10. 250. 2.

  11. Characterization of vanadium flow battery. Revised

    Energy Technology Data Exchange (ETDEWEB)

    Bindner, H.; Ekman, C.; Gehrke, O.; Isleifsson, F.

    2011-02-15

    This report summarizes the work done at Risoe-DTU testing a vanadium flow battery as part of the project ''Characterisation of Vanadium Batteries'' (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risoe DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses are power conversion in cell stacks/electrolyte, power converter, and auxiliary power consumption from pumps and controller. The efficiency was not influenced by the cycling of the battery. The response time for the battery is limited at 20kW/s by the ramp rate of the power converter. The battery can thus provide power and frequency support for the power system. The battery was operated together with a 11kW stall-regulated Gaia wind turbine to smooth the output of the wind turbine and during the tests the battery proved capable of firming the output of the wind turbine. Vanadium battery is a potential technology for storage based services to the power system provided investment and O and M cost are low enough and long term operation is documented. (Author)

  12. Vanadium proton exchange membrane water electrolyser

    Science.gov (United States)

    Noack, Jens; Roznyatovskaya, Nataliya; Pinkwart, Karsten; Tübke, Jens

    2017-05-01

    In order to reverse the reactions of vanadium oxygen fuel cells and to regenerate vanadium redox flow battery electrolytes that have been oxidised by atmospheric oxygen, a vanadium proton exchange membrane water electrolyser was set up and investigated. Using an existing cell with a commercial and iridium-based catalyst coated membrane, it was possible to fully reduce V3.5+ and V3+ solutions to V2+ with the formation of oxygen and with coulomb efficiencies of over 96%. The cell achieved a maximum current density of 75 mA/cm2 during this process and was limited by the proximity of the V(III) reduction to the hydrogen evolution reaction. Due to the specific reaction mechanisms of V(IV) and V(III) ions, V(III) solutions were reduced with an energy efficiency of 61%, making this process nearly twice as energy efficient as the reduction of V(IV) to V(III). Polarisation curves and electrochemical impedance spectroscopy were used to further investigate the losses of half-cell reactions and to find ways of further increasing efficiency and performance levels.

  13. Fragility–structure–conductivity relations in vanadium tellurite glass

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Yue, Yuanzheng; Rodrigues, Ana Candida Martins

    the ability to intercalate lithium-ions, it is a candidate as cathode material. Here, we investigate the correlation between liquid fragility, structure and electronic conductivity in a series of vanadium-tellurite glasses with varying vanadium concentration. We measure dynamic and thermodynamic fragility...

  14. Combined effect of vanadium and nickel on lipid peroxidation and ...

    African Journals Online (AJOL)

    use

    2011-12-12

    Dec 12, 2011 ... Signs of toxicity were observed following treatment with vanadium, not nickel nor combined vanadium and .... Kazakhstan. Animal treatment. Outbred 3-month-old male albino rats, weighing between 230 to. 235 g (mean) at the beginning of experiment, were obtained from ..... Vitamin E supplementation.

  15. Synergistic extraction of vanadium (V, IV) with dithizone

    Energy Technology Data Exchange (ETDEWEB)

    Akaiwa, H.; Kawamoto, H.; Hiyamuta, E. (Gunma Univ., Kiryu (Japan). Faculty of Technology)

    1981-11-01

    By employing the synergistic extraction technique, vanadium (V, IV) has been found to form the primary dithizonate in the presence of a synergist. The extraction of the element proceeds according to the following equations. VO/sub 2//sup +/ + H/sub 2/dz,sub(org) + TBPO sub(org) reversible VO/sub 2/(Hdz)(TBPO)sub(org) + H/sup +/, and VOOH/sup +/ + H/sub 2/dz,sub(org) + TOPO sub(org) reversible VOOH(Hdz)(TOPO)sub(org) + H/sup +/, where H/sub 2/dz, TBPO, and TOPO denote dithizone, tributylphosphine oxide and trioctylphosphine oxide, respectively, and the subscript org indicates the benzene phase. The resulting adduct VO/sub 2/(Hdz)(TBPO) has an absorption maximum at 503 nm and is stable for at least 1 h. However, the red color of VOOH(Hdz)(TOPO) in benzene fades away during the standing time, probably due to the dimerization of the initially extracted monomeric species.

  16. Low-temperature solution-processed hydrogen molybdenum and vanadium bronzes for an efficient hole-transport layer in organic electronics.

    Science.gov (United States)

    Xie, Fengxian; Choy, Wallace C H; Wang, Chuandao; Li, Xinchen; Zhang, Shaoqing; Hou, Jianhui

    2013-04-11

    A simple one-step method is reported to synthesize low-temperature solution-processed transition metal oxides (TMOs) of molybdenum oxide and vanadium oxide with oxygen vacancies for a good hole-transport layer (HTL). The oxygen vacancy plays an essential role for TMOs when they are employed as HTLs: TMO films with excess oxygen are highly undesirable for their application in organic electronics. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching

    Science.gov (United States)

    Shi, Qihua; Zhang, Yimin; Liu, Tao; Huang, Jing

    2018-01-01

    Fluorides are widely used to improve vanadium extraction from shale in China. Sulfuric acid baking-leaching (SABL) was investigated as a means of recovering vanadium which does not require the use of fluorides and avoids the productions of harmful fluoride-containing wastewater. Various effective factors were systematically studied and the experimental results showed that 90.1% vanadium could be leached from the shale. On the basis of phase transformations and structural changes after baking the shale, a mechanism of vanadium extraction from shale via SABL was proposed. The mechanism can be described as: (1) sulfuric acid diffusion into particles; (2) the formation of concentrated sulfuric acid media in the particles after water evaporation; (3) hydroxyl groups in the muscovite were removed and transient state [SO4 2-] was generated; and (4) the metals in the muscovite were sulfated by active [SO4 2-] and the vanadium was released. Thermodynamics modeling confirmed this mechanism.

  18. Exploring electrolyte preference of vanadium nitride supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bo; Chen, Zhaohui; Lu, Gang [Department of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Wang, Tianhu [School of Electrical Information and Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Ge, Yunwang, E-mail: ywgelit@126.com [Department of Electrical Engineering and Automation, Luoyang Institute of Science and Technology, Luoyang 471023 (China)

    2016-04-15

    Highlights: • Hierarchical VN nanostructures were prepared on graphite foam. • Electrolyte preference of VN supercapacitor electrodes was explored. • VN showed better capacitive property in organic and alkaline electrolytes than LiCl. - Abstract: Vanadium nitride hierarchical nanostructures were prepared through an ammonia annealing procedure utilizing vanadium pentoxide nanostructures grown on graphite foam. The electrochemical properties of hierarchical vanadium nitride was tested in aqueous and organic electrolytes. As a result, the vanadium nitride showed better capacitive energy storage property in organic and alkaline electrolytes. This work provides insight into the charge storage process of vanadium nitride and our findings can shed light on other transition metal nitride-based electrochemical energy storage systems.

  19. Vanadium and vanadium nitride thin films grown by high power impulse magnetron sputtering

    Science.gov (United States)

    Hajihoseini, H.; Gudmundsson, J. T.

    2017-12-01

    Thin vanadium and vanadium nitride films were grown on SiO2 by non-reactive and reactive high power impulse magnetron sputtering (HiPIMS), respectively. The film properties were compared to films grown by conventional dc magnetron sputtering (dcMS) at similar conditions. We explored the influence of the stationary magnetic confinement field strength on the film properties and the process parameters. The deposition rate is much lower for non-reactive sputtering by HiPIMS than for dcMS. Furthermore, for both dcMS and HiPIMS the deposition rate is lower for strong magnetic confinement. Structural characterization was carried out using x-ray diffraction and reflection methods as well as atomic force microscopy and scanning electron microscope. Both dcMS and HiPIMS grown vanadium films are polycrystalline with similar grain size regardless of magnetic field strength. For dcMS grown vanadium films the surface roughness is higher when a strong magnetic field is used. For both non-reactive growth of vanadium and reactive growth of vanadium nitride the HiPIMS process produces denser films with lower surface roughness than dcMS does. Lowering the magnetic field strength increases the deposition rate significantly for reactive HiPIMS while it increases only slightly in the reactive dcMS case. The films grown by HiPIMS with strong magnetic confinement exhibit higher density and lower roughness. We find that the operating pressure, growth temperature, discharge voltage and film thickness has influence on the properties of HiPIMS grown vanadium nitride films. The films are denser when grown at high temperature, high discharge voltage and low pressure. The density of those films is lower for thicker films and thicker films consist of larger grain size. For all the films explored, higher density coincides with lower surface roughness. Thus, the deposition method, magnetic field strength, growth temperature, discharge voltage, film thickness and growth pressure have a significant

  20. Mechanism of Enhancing Extraction of Vanadium from Stone Coal by Roasting with MgO

    Directory of Open Access Journals (Sweden)

    Fang Chen

    2017-02-01

    Full Text Available In this paper, the extraction of vanadium from stone coal by roasting with MgO and leaching with sulfuric acid has been investigated, and the mechanism analysis of stone coal roasting with MgO was studied. The results indicated that under the conditions that the mass fraction of the particles with grain size of 0–0.074 mm in raw ore was 75%, the roasting temperature was 500 °C, the roasting time was 1 h, MgO addition was 3 wt %, the sulfuric acid concentration was 20 vol %, the liquid-to-solid ratio was 1.5 mL/g, the leaching temperature was 95 °C, and leaching time was 2 h, resulting in a vanadium leaching efficiency of 86.63%, which increased by 7.73% compared with that of blank roasting. The mechanism analysis showed that the degree of calcite decomposition was low and, thus, magnesium vanadate was more easily formed than calcium vanadate below 500 °C. Moreover, magnesium vanadate was easier to dissolve than calcium vanadate during the sulfuric acid leaching process. Thus, the vanadium leaching efficiency was enhanced by using MgO as a roasting additive below 500 °C. Additionally, at high temperature the formation of tremolite would consume calcium oxide produced from the decomposition of calcite, thus, the formation of calcium vanadate was hindered, and V2O5 would react with MgO to form magnesium vanadate. Therefore, the vanadium leaching efficiency of roasting with MgO was higher than that of blank roasting at high temperature.

  1. 40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

    Science.gov (United States)

    2010-07-01

    ... for the extraction of uranium, radium and vanadium. Only vanadium byproduct production from uranium... uranium, radium and vanadium ores subcategory. 440.30 Section 440.30 Protection of Environment... SOURCE CATEGORY Uranium, Radium and Vanadium Ores Subcategory § 440.30 Applicability; description of the...

  2. Vanadium bromoperoxidase-catalyzed biosynthesis of halogenated marine natural products.

    Science.gov (United States)

    Carter-Franklin, Jayme N; Butler, Alison

    2004-11-24

    Marine red algae (Rhodophyta) are a rich source of bioactive halogenated natural products. The biogenesis of the cyclic halogenated terpene marine natural products, in particular, has attracted sustained interest in part because terpenes are the biogenic precursors of many bioactive metabolites. The first enzymatic asymmetric bromination and cyclization of a terpene, producing marine natural products isolated from red algae, is reported. Vanadium bromoperoxidase (V-BrPO) isolated from marine red algae (species of Laurencia, Plocamium, Corallina) catalyzes the bromination of the sesquiterpene (E)-(+)-nerolidol producing alpha-, beta-, and gamma-snyderol and (+)-3beta-bromo-8-epicaparrapi oxide. alpha-Snyderol, beta-snyderol, and (+)-3beta-bromo-8-epicaparrapi oxide have been isolated from Laurencia obtusa, and each have also been isolated from other species of marine red algae. gamma-Snyderol is a proposed intermediate in other bicyclo natural products. Single diastereomers of beta-snyderol, gamma-snyderol, and mixed diastereomers of (+)-3beta-bromo-8-epicaparrapi oxide (de = 20-25%) are produced in the enzyme reaction, whereas two diastereomers of these compounds are formed in the synthesis with 2,4,4,6-tetrabromocyclohexa-2,5-dienone (TBCO). V-BrPO likely functions by catalyzing the two-electron oxidation of bromide ion by hydrogen peroxide producing a bromonium ion or equivalent in the active site that brominates one face of the terminal olefin of nerolidol. These results establish V-BrPO's role in the biosynthesis of brominated cyclic sesquiterpene structures from marine red algae for the first time.

  3. Conductive porous vanadium nitride/graphene composite as chemical anchor of polysulfides for lithium-sulfur batteries

    Science.gov (United States)

    Sun, Zhenhua; Zhang, Jingqi; Yin, Lichang; Hu, Guangjian; Fang, Ruopian; Cheng, Hui-Ming; Li, Feng

    2017-03-01

    Although the rechargeable lithium-sulfur battery is an advanced energy storage system, its practical implementation has been impeded by many issues, in particular the shuttle effect causing rapid capacity fade and low Coulombic efficiency. Herein, we report a conductive porous vanadium nitride nanoribbon/graphene composite accommodating the catholyte as the cathode of a lithium-sulfur battery. The vanadium nitride/graphene composite provides strong anchoring for polysulfides and fast polysulfide conversion. The anchoring effect of vanadium nitride is confirmed by experimental and theoretical results. Owing to the high conductivity of vanadium nitride, the composite cathode exhibits lower polarization and faster redox reaction kinetics than a reduced graphene oxide cathode, showing good rate and cycling performances. The initial capacity reaches 1,471 mAh g-1 and the capacity after 100 cycles is 1,252 mAh g-1 at 0.2 C, a loss of only 15%, offering a potential for use in high energy lithium-sulfur batteries.

  4. Dynamic modelling of the effects of ion diffusion and side reactions on the capacity loss for vanadium redox flow battery

    Science.gov (United States)

    Tang, Ao; Bao, Jie; Skyllas-Kazacos, Maria

    The diffusion of vanadium ions across the membrane along with side reactions can have a significant impact on the capacity of the vanadium redox flow battery (VFB) over long-term charge-discharge cycling. Differential rates of diffusion of the vanadium ions from one half-cell into the other will facilitate self-discharge reactions, leading to an imbalance between the state-of-charge of the two half-cell electrolytes and a subsequent drop in capacity. Meanwhile side reactions as a result of evolution of hydrogen or air oxidation of V 2+ can further affect the capacity of the VFB. In this paper, a dynamic model is developed based on mass balances for each of the four vanadium ions in the VFB electrolytes in conjunction with the Nernst Equation. This model can predict the capacity as a function of time and thus can be used to determine when periodic electrolyte remixing or rebalancing should take place to restore cell capacity. Furthermore, the dynamic model can be potentially incorporated in the control system of the VFB to achieve long term optimal operation. The performance of three different types of membranes is studied on the basis of the above model and the simulation results together with potential operational issues are analysed and discussed.

  5. Thermolysis of Half-Sandwich Vanadium(V) Imido Complexes to Generate Vanadium(III) Imido Species via a Vanadium(IV) Intermediate

    NARCIS (Netherlands)

    Batinas, Aurora A.; Dam, Jeroen; Meetsma, Auke; Hessen, Bart; Bouwkamp, Marco W.

    2010-01-01

    Thermolysis of half-sandwich vanadium imido complexes Cp(RN)V(i-Pr(2)N)Me (R = p-Tol, 1a; R = t-Bu, 1b) results in a mixture of products, including vanadium(IV) dimers [CpVMe](2)(mu-RN)(2), i-Pr(2)NH, i-PrNCMe(2), CH(4), and one or more paramagnetic species. In the presence of dmpe (dmpe =

  6. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    Science.gov (United States)

    Madiba, I. G.; Émond, N.; Chaker, M.; Thema, F. T.; Tadadjeu, S. I.; Muller, U.; Zolliker, P.; Braun, A.; Kotsedi, L.; Maaza, M.

    2017-07-01

    Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO2) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO2 phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO2 structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V-V inter-dimer distance, which in turns favours the presence of the VO2 metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V4+ towards V5+ is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the valence band. Our observations suggest that gamma radiations induce the formation of Frenkel pairs. Moreover, THz transmission measurements show that the long range structure of VO2 remains intact after irradiation whilst the electrical measurements evidence that the coating resistivity decreases with gamma irradiation and that their transition temperature is slightly reduced for high gamma ray doses. Even though gamma rays are only one of the sources of radiations that are encountered in space environment, these results are very promising with regards to the potential of integration of such VO2 films as a protective coating for spacecrafts.

  7. Separation of Molybdenum, Vanadium and Nickel by Liquid-Liquid Extraction

    OpenAIRE

    COŞAR, T.

    2014-01-01

    Elements in the ash of asphaltites that is used in thermal central for power generation units are Mo, V, U, Ti and Ni. The main goal of this study was to separate molybdenum, vanadium and nickel from the aqueous solution. The quantities of the above elements in solution were in the range of 50-80 ppm. The separate these elements from solution, the liquid-liquid extraction method was applied to samples. Alamine 336 was used as extractant. During the reduction-oxidation processes, single and mu...

  8. Electrical quadruple hysteresis in Pd-doped vanadium pentoxide nanowires due to water adsorption

    Directory of Open Access Journals (Sweden)

    Byung Hoon Kim, Soon-Young Oh, Han Young Yu, Won G Hong, Yong Ju Yun, Yark Yeon Kim and Hae Jin Kim

    2010-01-01

    Full Text Available Humidity-dependent current–voltage (I–V characteristics of Pd-doped vanadium pentoxide nanowires (Pd-VONs were investigated. Electrical quadruple hysteresis (QH was observed and attributed to the large amount of water molecules adsorbed on the nanowires. Using QH in Pd-VONs, the reaction of water with PdO was interpreted as the water molecules are desorbed and then dissociated with increasing bias voltage. Owing to the dissociated H+ and OH− ions, PdO is reduced and oxidized. As a result, water molecules recombine as the bias voltage is decreased.

  9. Large Spin Hall Angle in Vanadium Film

    Science.gov (United States)

    Wang, Tao; Fan, Xin; Wang, Wenrui; Xie, Yunsong; Warsi, Muhammad A.; Wu, Jun; Chen, Yunpeng; Lorenz, Virginia O.; Xiao, John Q.

    We report the large spin Hall angle observed in Vanadium film with small grain size and distorted lattice parameter. The spin Hall angle is quantified by measuring current-induced spin-orbit torque in V/CoFeB bilayer using optical spin torque magnetometer based on polar magneto-optical Kerr effect (MOKE). The spin Hall angle as large as θSH = -0.071 has been observed in V/CoFeB bilayer Structural analysis, using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), confirms films grown at room temperature have very small grain size and enlarged lattice parameter. The Vanadium films with distorted crystal structure also have high resistivity (>200 μΩ cm) and long spin diffusion length (~16.3 nm) measured via spin pumping experiment. This finding of spin Hall effect enhancement in more disordered structure will provide insights for understanding and exploiting materials with strong spin orbit interaction, especially in light 3d transition metals which promise long spin diffusion length.

  10. Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(VOxide as a PEDOT:PSS Replacement

    Directory of Open Access Journals (Sweden)

    Frederik C. Krebs

    2011-01-01

    Full Text Available The use of hydrated vanadium(Voxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET and had the structure PET/ITO/ZnO/P3HT:PCBM/V2O5·(H2On/Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(Voxide layers were processed by slot-die coating. The hydrated vanadium(Voxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP. Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(Voxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(Voxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker.

  11. Vanadium and nickel in petroleums of bituminous Tatar rocks

    Energy Technology Data Exchange (ETDEWEB)

    Aigistova, S.Kh.; Safiullina, G.Kh.; Sadykov, A.N.; Kharlamov, V.A.

    1984-01-01

    The vanadium and nickel contents of petroleum obtained from bituminous rock of Ashal'chinsk, Akhmat, Gorskii, Katerchinsk, Klinsk (Studeno-Klyuchev), West-Chumachkin, Mordovian-Karmal' and Pokrov deposits, was determined polarographically. The vanadium concentration range in these petroleums is 0.01-0.09 and nickel 0.009-0.05 wt.%. According to results previously obtained, vanadium and nickel contents in ordinary petroleum of this country are no higher than 0.010 and 0.0014 wt.%, respectively. 3 references, 1 table.

  12. Vanadium-base alloys for fusion reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined.

  13. Selenium, Vanadium, and Chromium as Micronutrients to Improve Metabolic Syndrome.

    Science.gov (United States)

    Panchal, Sunil K; Wanyonyi, Stephen; Brown, Lindsay

    2017-03-01

    Trace metals play an important role in the proper functioning of carbohydrate and lipid metabolism. Some of the trace metals are thus essential for maintaining homeostasis, while deficiency of these trace metals can cause disorders with metabolic and physiological imbalances. This article concentrates on three trace metals (selenium, vanadium, and chromium) that may play crucial roles in controlling blood glucose concentrations possibly through their insulin-mimetic effects. For these trace metals, the level of evidence available for their health effects as supplements is weak. Thus, their potential is not fully exploited for the target of metabolic syndrome, a constellation that increases the risk for cardiovascular disease and type 2 diabetes. Given that the prevalence of metabolic syndrome is increasing throughout the world, a simpler option of interventions with food supplemented with well-studied trace metals could serve as an answer to this problem. The oxidation state and coordination chemistry play crucial roles in defining the responses to these trace metals, so further research is warranted to understand fully their metabolic and cardiovascular effects in human metabolic syndrome.

  14. Numerical modeling of an all vanadium redox flow battery.

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Jonathan R.; Brunini, Victor E.; Moffat, Harry K.; Martinez, Mario J.

    2014-01-01

    We develop a capability to simulate reduction-oxidation (redox) flow batteries in the Sierra Multi-Mechanics code base. Specifically, we focus on all-vanadium redox flow batteries; however, the capability is general in implementation and could be adopted to other chemistries. The electrochemical and porous flow models follow those developed in the recent publication by [28]. We review the model implemented in this work and its assumptions, and we show several verification cases including a binary electrolyte, and a battery half-cell. Then, we compare our model implementation with the experimental results shown in [28], with good agreement seen. Next, a sensitivity study is conducted for the major model parameters, which is beneficial in targeting specific features of the redox flow cell for improvement. Lastly, we simulate a three-dimensional version of the flow cell to determine the impact of plenum channels on the performance of the cell. Such channels are frequently seen in experimental designs where the current collector plates are borrowed from fuel cell designs. These designs use a serpentine channel etched into a solid collector plate.

  15. Mesoporous tungsten oxynitride as electrocatalyst for promoting redox reactions of vanadium redox couple and performance of vanadium redox flow battery

    Science.gov (United States)

    Lee, Wonmi; Jo, Changshin; Youk, Sol; Shin, Hun Yong; Lee, Jinwoo; Chung, Yongjin; Kwon, Yongchai

    2018-01-01

    For enhancing the performance of vanadium redox flow battery (VRFB), a sluggish reaction rate issue of V2+/V3+ redox couple evaluated as the rate determining reaction should be addressed. For doing that, mesoporous tungsten oxide (m-WO3) and oxyniride (m-WON) structures are proposed as the novel catalysts, while m-WON is gained by NH3 heat treatment of m-WO3. Their specific surface area, crystal structure, surface morphology and component analysis are measured using BET, XRD, TEM and XPS, while their catalytic activity for V2+/V3+ redox reaction is electrochemically examined. As a result, the m-WON shows higher peak current, smaller peak potential difference, higher electron transfer rate constant and lower charge transfer resistance than other catalysts, like the m-WO3, WO3 nanoparticle and mesoporous carbon, proving that it is superior catalyst. Regarding the charge-discharge curve tests, the VRFB single cell employing the m-WON demonstrates high voltage and energy efficiencies, high specific capacity and low capacity loss rate. The excellent results of m-WON are due to the reasons like (i) reduced energy band gap, (ii) reaction familiar surface functional groups and (ii) greater electronegativity.

  16. Vanadium - investigations on supply and demand of mineral raw materials

    Energy Technology Data Exchange (ETDEWEB)

    Eggert, P.; Kippenberger, C.; Kruszona, M.; Schmidt, H.; Wettig, E.

    1981-11-01

    Conclusions which are drawn in the latest report of the Federal Institute for Geosciences and Mineral Resources, Hanover, and the German Institute for Economic Research, Berlin, on the steel additive vanadium are presented.

  17. Method to Remove Uranium/Vanadium Contamination from Groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Metzler, Donald R.; Morrison Stanley

    2004-07-27

    A process for removing uranium/vanadium-based contaminants from groundwater using a primary in-ground treatment media and a pretreatment media that chemically adjusts the groundwater contaminant to provide for optimum treatment by the primary treatment media.

  18. Exploring a novel approach to fabricate vanadium carbide ...

    Indian Academy of Sciences (India)

    -shell structure; composite materials; mesoporous material; solid-state reaction. ... A novel approach to the fabrication of vanadium carbide encapsulated into carbon nanotube (VC@C) core-shell structured composite by thermal treatment with ...

  19. Remobilization of pentavalent antimony and vanadium from a granular iron hydroxide material--a comparative study of different leaching systems.

    Science.gov (United States)

    Kolbe, Falko; Weiss, Holger; Wennrich, Rainer; Lorenz, Wilhelm Georg; Daus, Birgit

    2011-09-30

    The remobilization of antimony and vanadium from previously loaded commercial granular ferric-hydroxide GEH material (intended for water treatment) was examined by using a sequential extraction procedure and three different leaching systems to evaluate their physicochemical mobility and potential availability under different simulated environmental conditions. A classical batch extraction, an extraction cell (EC) and rotating-coiled columns (RCC) were used as extraction systems. For each system it could be shown that the content of ion-exchangeable antimony and vanadium in previously loaded material is negligible (extraction time and the possibility of generating information to the leaching kinetics. It is shown that the efficiency of the three leaching systems is quite different employing Wenzel's sequential fractionation protocol. Only by working with RCC, the iron (hydr)oxide matrix was completely dissolved within four steps resulting in the total mobilization of antimony and vanadium. EC seems to be less suitable for leaching studies of Sb and V sorbed on iron(hydr)oxide. The remobilizable proportion of the several fractions was lower in comparison to batch and RCC and seems to be a result of an agglomeration of the GEH in the EC device. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. A new vanadium(V) persulfide complex: (NEt[sub 4])[VO(S[sub 2])[sub 2](bpy)

    Energy Technology Data Exchange (ETDEWEB)

    Castro, S.L.; Martin, J.D.; Christou, G. (Indiana Univ., Bloomington, IN (United States))

    1993-06-23

    Over the last several years, the authors have been investigating nonorganometallic vanadium/sulfide chemistry, concentrating on the higher metal oxidation states (III-V). They have found this area to be rich in structural types and reactivity characteristics. Together with related efforts by others, an impressive pool of complexes has now been made available spanning a variety of nuclearities and oxidation levels, including mixed valency. The authors' interest in this area stems from the conversion of crude oil vanadyl impurities to polymeric vanadium sulfides under the sulfur-rich conditions present during catalytic hydrodesulfurization and hydrodemetalation processes. A variety of discrete V/S species are probably forming as intermediates, and the characterization of V/S species thus becomes of relevance to the understanding of these transformations. The area of impact of the present work is vanadium persulfide chemistry. A number of V complexes of various metal nuclearities are now known that contain S[sub 2][sup 2[minus

  1. Tackling capacity fading in vanadium flow batteries with amphoteric membranes

    Science.gov (United States)

    Oldenburg, Fabio J.; Schmidt, Thomas J.; Gubler, Lorenz

    2017-11-01

    Capacity fading and poor electrolyte utilization caused by electrolyte imbalance effects are major drawbacks for the commercialization of vanadium flow batteries (VFB). The influence of membrane type (cationic, anionic, amphoteric) on these effects is studied by determining the excess and net flux of each vanadium ion in an operating VFB assembled with a cation exchange membrane (CEM), Nafion® NR212, an anion exchange membrane (AEM), Fumatech FAP-450, and an amphoteric ion exchange membrane (AIEM) synthesized in-house. It is shown that the net vanadium flux, accompanied by water transport, is directed towards the positive side for the CEM and towards the negative side for the AEM. The content of cation and anion exchange groups in the AIEM is adjusted via radiation grafting to balance the vanadium flux between the two electrolyte sides. With the AIEM the net vanadium flux is significantly reduced and capacity fading due to electrolyte imbalances can be largely eliminated. The membrane's influence on electrolyte imbalance effects is characterized and quantified in one single charge-discharge cycle by analyzing the content of the four different vanadium species in the two electrolytes. The experimental data recorded herewith conclusively explains the electrolyte composition after 80 cycles.

  2. The effects of surface modification on carbon felt electrodes for use in vanadium redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Jae; Kim, Young-Jun; Kim, Jae-Hun [Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816 (Korea, Republic of); Park, Min-Sik, E-mail: parkms@keti.re.kr [Advanced Batteries Research Center, Korea Electronics Technology Institute, Seongnam, Gyeonggi 463-816 (Korea, Republic of)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We observed the physical and chemical changes on the surface of carbon felts after various surface modifications. Black-Right-Pointing-Pointer The surface area and chemistry of functional groups formed on the surface of carbon felt are critical to determine the kinetics of the redox reactions of vanadium ions. Black-Right-Pointing-Pointer By incorporation of the surface modifications into the electrode preparation, the electrochemical activity of carbon felts could be notably enhanced. - Abstract: The surface of carbon felt electrodes has been modified for improving energy efficiency of vanadium redox flow batteries. For comparative purposes, the effects of various surface modifications such as mild oxidation, plasma treatment, and gamma-ray irradiation on the electrochemical properties of carbon felt electrodes were investigated at optimized conditions. The cell energy efficiency was improved from 68 to 75% after the mild oxidation of the carbon felt at 500 Degree-Sign C for 5 h. This efficiency improvement could be attributed to the increased surface area of the carbon felt electrode and the formation of functional groups on its surface as a result of the modification. On the basis of various structural and electrochemical characterizations, a relationship between the surface nature and electrochemical activity of the carbon felt electrodes is discussed.

  3. Nanoparticles of Low-Valence Vanadium Oxyhydroxides: Reaction Mechanisms and Polymorphism Control by Low-Temperature Aqueous Chemistry.

    Science.gov (United States)

    Besnardiere, Julie; Petrissans, Xavier; Ribot, François; Briois, Valérie; Surcin, Christine; Morcrette, Mathieu; Buissette, Valérie; Le Mercier, Thierry; Cassaignon, Sophie; Portehault, David

    2016-11-07

    An aqueous synthetic route at 95 °C is developed to reach selectively three scarcely reported vanadium oxyhydroxides. Häggite V2O3(OH)2, Duttonite VO(OH)2, and Gain's hydrate V2O4(H2O)2 are obtained as nanowires, nanorods, and nanoribbons, with sizes 1 order of magnitude smaller than previously reported. X-ray absorption spectroscopy provides evidence that vanadium in these phases is V+IV. Combined with FTIR, XRD, and electron microscopy, it yields the first insights into formation mechanisms, especially for Häggite and Gain's hydrate. This study opens the way for further investigations of the properties of novel V+IV (oxyhydr)oxides nanostructures.

  4. Localization of Vanabins, Vanadium-Binding Proteins, in the Blood Cells of the Vanadium-Rich Ascidian, Ascidia sydneiensis samea(Physiology)

    OpenAIRE

    Nobuo, Yamaguchi; Yuko, Amakawa; Hiroshi, Yamada; Tatsuya, Ueki; Hitoshi, Michibata; Marine Biological Laboratory, Graduate School of Science, Hiroshima University; Department of Neuroscience, Graduate School of Medicine and Dentistry, Okayama University; Molecular Physiology Laboratory, Department of Biological Science, Graduate School of Science, Hiroshima University

    2006-01-01

    Some species of the family Ascidiidae accumulate vanadium in concentrations in excess of 350mM, which is about 10^7-fold higher than the concentration of vanadium in seawater. In these species, signet ring cells with a single large vacuole in which vanadium ions are contained function as vanadium-accumulating cells. These have been termed vanadocytes. We recently isolated five vanadium-binding proteins, which we named Vanabinl, Vanabin2, Vanabin3, Vanabin4, and VanabinP, from vanadocytes of t...

  5. Comparison of Ultrasound-Assisted and Regular Leaching of Vanadium and Chromium from Roasted High Chromium Vanadium Slag

    Science.gov (United States)

    Wen, Jing; Jiang, Tao; Gao, Huiyang; Liu, Yajing; Zheng, Xiaole; Xue, Xiangxin

    2018-02-01

    Ultrasound-assisted leaching (UAL) was used for vanadium and chromium leaching from roasted material obtained by the calcification roasting of high-chromium-vanadium slag. UAL was compared with regular leaching. The effect of the leaching time and temperature, acid concentration, and liquid-solid ratio on the vanadium and chromium leaching behaviors was investigated. The UAL mechanism was determined from particle-size-distribution and microstructure analyses. UAL decreased the reaction time and leaching temperature significantly. Furthermore, 96.67% vanadium and less than 1% chromium were leached at 60°C for 60 min with 20% H2SO4 at a liquid-solid ratio of 8, which was higher than the maximum vanadium leaching rate of 90.89% obtained using regular leaching at 80°C for 120 min. Ultrasonic waves broke and dispersed the solid sample because of ultrasonic cavitation, which increased the contact area of the roasted sample and the leaching medium, the solid-liquid mass transfer, and the vanadium leaching rate.

  6. A tunable hybrid metamaterial absorber based on vanadium oxide films

    Science.gov (United States)

    Wen, Qi-Ye; Zhang, Huai-Wu; Yang, Qing-Hui; Chen, Zhi; Long, Yang; Jing, Yu-Lan; Lin, Yuan; Zhang, Pei-Xin

    2012-06-01

    A tunable hybrid metamaterial absorber (MA) in the microwave band was designed, fabricated and characterized. The hybrid MA was realized by incorporating a VO2 film into the conventional resonant MA. By thermally triggering the insulator-metal phase transition of the VO2 film, the impedance match condition was broken and a deep amplitude modulation of about 63.3% to the electromagnetic wave absorption was achieved. A moderate blue-shift of the resonance frequency was observed which is promising for practical applications. This VO2-based MA exhibits many advantages such as strong tunability, frequency agility, simple fabrication and ease of scaling to the terahertz band.

  7. Adsorption of ammonia on vanadium-antimony mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, Hernan; German, Estefania [Departamento e Instituto de Fisica del Sur, Universidad Nacional del Sur-CONICET, Avda. Alem 1253, (8000) Bahia Blanca (Argentina); Juan, Alfredo, E-mail: cajuan@uns.edu.ar [Departamento e Instituto de Fisica del Sur, Universidad Nacional del Sur-CONICET, Avda. Alem 1253, (8000) Bahia Blanca (Argentina); Irigoyen, Beatriz [Departamento de Ingenieria Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Pabellon de Industrias, Ciudad Universitaria, (1428) Ciudad Autonoma de Buenos Aires (Argentina)

    2012-02-01

    We analyzed the adsorption of ammonia (NH{sub 3}) on the VSbO{sub 4}(1 1 0) catalyst surface using density functional theory (DFT) calculations. We followed the evolution of the chemical bonds between different atoms of the resulting NH{sub 3}/VSbO{sub 4} system and the changes in the electronic structure of the catalyst. NH{sub 3} preferential adsorption geometries were analyzed through the crystal orbital overlap population (COOP) concept and the density of states (DOS) curves. The VSbO{sub 4}(1 1 0) surface exhibits Lewis and Bronsted acid sites on which the ammonia molecule can interact. On the Lewis acid site, NH{sub 3} adsorption resulted in the interaction between the N and a surface V-isolated cation. On Bronsted acid site, N interacted with a surface H coming from the chemical dissociation of water. The COOP analysis indicate that NH{sub 3} interaction on the VSbO{sub 4}(1 1 0) surface is weak. In addition, the DOS curves show more developed electronic interactions for NH{sub 3} adsorption on Lewis acid site than over Bronsted acid site.

  8. Structure, hydrolysis, and diffusion of aqueous vanadium ions from Car-Parrinello molecular dynamics

    Science.gov (United States)

    Jiang, Zhen; Klyukin, Konstantin; Alexandrov, Vitaly

    2016-09-01

    A molecular level understanding of the properties of electroactive vanadium species in aqueous solution is crucial for enhancing the performance of vanadium redox flow batteries. Here, we employ Car-Parrinello molecular dynamics simulations based on density functional theory to investigate the hydration structures, first hydrolysis reaction, and diffusion of aqueous V2+, V3+, VO2+, and VO 2+ ions at 300 K. The results indicate that the first hydration shell of both V2+ and V3+ contains six water molecules, while VO2+ is coordinated to five and VO 2+ to three water ligands. The first acidity constants (pKa) estimated using metadynamics simulations are 2.47, 3.06, and 5.38 for aqueous V3+, VO 2+ , and VO2+, respectively, while V2+ is predicted to be a fairly weak acid in aqueous solution with a pKa value of 6.22. We also show that the presence of chloride ions in the first coordination sphere of the aqueous VO 2+ ion has a significant impact on water hydrolysis leading to a much higher pKa value of 4.8. This should result in a lower propensity of aqueous VO 2+ for oxide precipitation reaction in agreement with experimental observations for chloride-based electrolyte solutions. The computed diffusion coefficients of vanadium species in water at room temperature are found to increase as V 3 + < VO 2 + < V O 2 + < V 2 + and thus correlate with the simulated hydrolysis constants, namely, the higher the pKa value, the greater the diffusion coefficient.

  9. X-ray absorption of Azotobacter vinelandii vanadium nitrogenase

    Energy Technology Data Exchange (ETDEWEB)

    George, G.N.; Coyle, C.L.; Hales, B.J.; Cramer, S.P.

    1988-06-08

    Evidence for the existence of a vanadium-containing nitrogenase has existed for more than half a century, but progress in understanding this enzyme has only come recently. In 1980, Bishop and co-workers proposed that an alternative nitrogen-fixing enzyme exists in Azotobacter vinelandii and subsequently proposed that vanadium was involved. In 1986, Robson et al. demonstrated clearly that the alternate nitrogenase from Azotobacter chroococcum, Acl*, contained vanadium instead of molybdenum. Hales et al. have shown the vanadium is also found in the Azotobacter vinelandii alternative component I, Avl'. The molybdenum and vanadium nitrogenase proteins are similar in many respects. Like the molybdenum enzyme, both Acl* and Avl' exhibit an EPR spectrum characteristic of a species with an S = 3/2 ground state; Avl' also contains the so-called P-clusters. Additionally Acl* has recently been shown to possess an N-methylformamide soluble cofactor, FeVco, analogous to the well-known iron-molybdenum cofactor FeMoco. Arber et al. have reported X-ray absorption spectra for the Acl* enzyme and interpreted the EXAFS as evidence for a V-Fe-S cluster. The local vanadium structure is proposed to resemble a recently synthesized cubane-like VFe/sub 3/S/sub 4/ cluster, and analogies are drawn with the EXAFS-derived structure reported for the molybdenum nitrogenases. The authors report herein an X-ray absorption spectroscopic study of A. vinelandii vanadium nitrogenase, Avl', which supports and extends the work of Arber et al.

  10. Vanadium-Catalyzed Enantioselective Desymmetrization of meso-Secondary Allylic Alcohols and Homoallylic Alcohols

    OpenAIRE

    Li, Zhi; Zhang, Wei; Hisashi Yamamoto, H.

    2008-01-01

    Vanadium-catalyzed epoxidation has extended substrate scope. In addition to various bis-allylic alcohols, bis-homoallylic alcohols can also be desymmetrized using our Vanadium-Bis-hydroxamic acid complexes.

  11. Complexation of vanadium with amidoxime and carboxyl groups. Uncovering the competitive role of vanadium in uranium extraction from seawater

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cong-Zhi; Wu, Qun-Yan; Lan, Jian-Hui; Shi, Wei-Qun [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Chai, Zhi-Fang [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Soochow Univ., Suzhou (China). School of Radiological and Interdisciplinary Sciences (RAD-X); Wu, Guo-Zhong [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Applied Physics

    2017-09-01

    At present, amidoxime-based adsorbents are considered to be the most promising materials for extraction of uranium from seawater. However, the high concentrations of transition metals especially vanadium strongly compete with uranium in the sequestration process, which is extremely limited the commercial use of amidoxime-based adsorbents. In this work, the coordination modes, bonding nature, and stabilities of possible vanadium(IV) (VO{sup 2+}) and (V) (VO{sub 2}{sup +}, VO{sup 3+}, V{sup 5+}) complexes with amidoximate (AO{sup -}), carboxyl (Ac{sup -}), glutarimidedioximate (HA{sup -}) and deprotonated glutarimidedioximate (A{sup 2-}) on single and double alkyl chains (R=C{sub 13}H{sub 26}) are systematically explored by quantum chemical calculations. Different from the uranyl (UO{sub 2}{sup 2+}) complexes, the AO{sup -} groups of the vanadium(IV) and (V) complexes prefer to coordinate as monodentate and chelate ligands, while few species with AO{sup -} groups in η{sup 2}-binding mode have been observed in the vanadium complexes. Besides, the vanadium complexes are predicted to have obvious covalent metal-ligand bonds. According to thermodynamic stability analysis, all the vanadium complexes with AO{sup -}, Ac{sup -}, HA{sup -} and A{sup 2-} ligands on double alkyl chains are found to be more stable than corresponding complexes with ligands on a single chain. The synergistic effect of the amidoxime and carboxyl groups can be observed in most of VO{sub 2}{sup +} and VO{sup 3+} complexes with mixed ligands (AO{sup -}/Ac{sup -}). The vanadium(IV) and (V) complexes are more stable than the corresponding uranyl complexes, and the adsorption capability of the amidoxime-based adsorbents toward vanadium(V) ions decrease in the order of VO{sub 2}{sup +}>VO{sup 3+}> V{sup 5+}. The dioxovanadium cation VO{sub 2}{sup +} is predicted to form multinuclear vanadium complex in the sequestration process, possibly resulting in higher stable VO{sub 2}{sup +} complexes. Therefore

  12. Vanadium uptake by biomass of Coprinus comatus and their effect on hyperglycemic mice.

    Science.gov (United States)

    Han, Chunchao; Cui, Bo; Wang, Yingzi

    2008-07-01

    The Vanadium uptake by Coprinus comatus and their co-effect on hyperglycemic mice were studied. By fermentation and AAS analysis, the optimal concentration of vanadium in medium was 0.4%, and the content of vanadium accumulated in the mycelia was 3,528.0 microg/g. At the concentration of 0.4%, the vanadium-associated toxicity was reduced, and its anti-diabetic effects were maintained.

  13. A Novel Eco-Friendly Vanadium Precipitation Method by Hydrothermal Hydrogen Reduction Technology

    OpenAIRE

    Guobin Zhang; Yimin Zhang; Shenxu Bao; Jing Huang; Liuhong Zhang

    2017-01-01

    In view of the serious pollution problems caused by the traditional vanadium precipitation process, the eco-friendly technology of hydrothermal hydrogen reduction was first applied to precipitate phase pure vanadium sesquioxide (V2O3) products from stripped pentavalent vanadium (V (V)) solution extracted from vanadium-bearing shale. Thermodynamic analysis demonstrate the method of hydrothermal hydrogen reduction is feasible for precipitating V2O3 from V (V) solution at a suitable pH range, an...

  14. The Vanadium Iodoperoxidase from the marine flavobacteriaceae species Zobellia galactanivorans reveals novel molecular and evolutionary features of halide specificity in the vanadium haloperoxidase enzyme family.

    Science.gov (United States)

    Fournier, Jean-Baptiste; Rebuffet, Etienne; Delage, Ludovic; Grijol, Romain; Meslet-Cladière, Laurence; Rzonca, Justyna; Potin, Philippe; Michel, Gurvan; Czjzek, Mirjam; Leblanc, Catherine

    2014-12-01

    Vanadium haloperoxidases (VHPO) are key enzymes that oxidize halides and are involved in the biosynthesis of organo-halogens. Until now, only chloroperoxidases (VCPO) and bromoperoxidases (VBPO) have been characterized structurally, mainly from eukaryotic species. Three putative VHPO genes were predicted in the genome of the flavobacterium Zobellia galactanivorans, a marine bacterium associated with macroalgae. In a phylogenetic analysis, these putative bacterial VHPO were closely related to other VHPO from diverse bacterial phyla but clustered independently from eukaryotic algal VBPO and fungal VCPO. Two of these bacterial VHPO, heterogeneously produced in Escherichia coli, were found to be strictly specific for iodide oxidation. The crystal structure of one of these vanadium-dependent iodoperoxidases, Zg-VIPO1, was solved by multiwavelength anomalous diffraction at 1.8 Å, revealing a monomeric structure mainly folded into α-helices. This three-dimensional structure is relatively similar to those of VCPO of the fungus Curvularia inaequalis and of Streptomyces sp. and is superimposable onto the dimeric structure of algal VBPO. Surprisingly, the vanadate binding site of Zg-VIPO1 is strictly conserved with the fungal VCPO active site. Using site-directed mutagenesis, we showed that specific amino acids and the associated hydrogen bonding network around the vanadate center are essential for the catalytic properties and also the iodide specificity of Zg-VIPO1. Altogether, phylogeny and structure-function data support the finding that iodoperoxidase activities evolved independently in bacterial and algal lineages, and this sheds light on the evolution of the VHPO enzyme family. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  15. A new sensitive electrochemical method for the determination of vanadium(IV) and vanadium(V) in Benfield sample.

    Science.gov (United States)

    Qureshi, Munawar Saeed; Mohd Yusoff, Abdull Rahim bin; Shah, Afzal; Nafady, Ayman; Sirajuddin

    2015-01-01

    Vanadium(IV) and vanadium(V) can be determined by using differential pulse cathodic stripping voltammetry technique (DPCSV). Cupferron (ammonium N-nitrosophenylhydroxylamine) was used as ligand to form complex compounds with vanadium ions in Britton-Robinson buffer (BRB) solution. At concentration lower than 1.0×10(-6) M, both V(IV) and V(V) cupferron complexes showed a single cathodic peak at -0.576 V in BRB of pH 4; thus V(IV) and V(V) ions cannot be differentiated at low concentration. However, the ionic species of vanadium can be differentiated at high concentration in the presence of cupferron. Parameters including pH of BRB solution, initial potential and accumulation potential were optimized. Under the optimized parameters, the limit of detection (LOD) was 0.09 nM, and the peak current was linear in the concentration range 0.01-0.9 µM total vanadium ions. The determination of V(IV) and V(V) ions was carried out at higher concentration in the sample using calibration plot method. At higher concentration range of 10-60 µM V(IV) and V(V) ions were determined with LOD of 1.2 and 1.1 µM, respectively. The developed method was successfully applied to 10,00,000 fold diluted Benfield sample and 0.6227 M total vanadium ions were determined. The determination of V(IV) and V(V) ions were also successfully carried out in artificial sample as well as Benfield sample (dilution factor, 10,000). The concentration of V(IV) and V(V) ions was 22.52 µM and 38.91 µM, respectively, giving total vanadium concentration of 0.6143 M in Benfield sample. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Madiba, I.G., E-mail: madibagiven@gmail.com [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Émond, N.; Chaker, M. [Institut National de la Recherche Scientifique (INRS),1650 Blvd. Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Thema, F.T. [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Tadadjeu, S.I. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Muller, U.; Zolliker, P. [Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Braun, A. [ETH Zurich, Swiss Federal Institute of Technology, CH-8057, Zurich (Switzerland); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Kotsedi, L. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); and others

    2017-07-31

    Highlights: • Synthesis of VO{sub 2} thin films by Reactive pulsed laser deposition has been achieved. • Properties VO{sub 2} remain mainly unaffected when subjected to gamma ray doses similar to those encountered during space missions. • The long range crystal structure of VO{sub 2} remains intact upon irradiation on different doses up to 100 kGy. • XPS reveals a shift from V{sup 4+} to V{sup 5+} oxidation state upon irradiation, due to the frenkel pair formation on the surface. • Irradiated films show the characteristic SMT of VO{sub 2}, although the electrical and optical properties are slightly affected. - Abstract: Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO{sub 2}) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO{sub 2} phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO{sub 2} structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V–V inter-dimer distance, which in turns favours the presence of the VO{sub 2} metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V{sup 4+} towards V{sup 5+} is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the

  17. Gastroprotective effect of vanadium in rats - the roles of gastric acid ...

    African Journals Online (AJOL)

    Vanadium (various forms) has been proven to be beneficial in the treatment of certain diseases, especially diabetes. Reports have it that vanadium may protect the stomach from gastric ulcerogens such as ethanol and acid. This study was designed to investigate the probable mechanism Vanadium exerts its' ...

  18. Method for Vanadium Speciation in Aqueous Samples by HPLC-ICP ...

    African Journals Online (AJOL)

    Method for Vanadium Speciation in Aqueous Samples by HPLC-ICP-OES. M Hu, PP Coetzee. Abstract. A method for vanadium speciation is proposed. The method uses a low concentration eluent, 10 mmol L–1 EDTA and 14 mmol L–1 sodium carbonate, for the ion chromatographic separation of vanadium species at a ...

  19. Method for Vanadium Speciation in Aqueous Samples by HPLC-ICP ...

    African Journals Online (AJOL)

    NJD

    methods can only measure the total concentration of vanadium, or one of the two vanadium species, particularly V(V).4–6 Some two-step methods for the determination of the two vanadium species7–10 have been proposed by several groups. These methods normally measure one of the two species in one step, and in the.

  20. Vanadium Extraction from Refractory Stone Coal Using Novel Composite Additive

    Science.gov (United States)

    Cai, Z. L.; Zhang, Y. M.; Liu, T.; Huang, J.

    2015-11-01

    Based on the novel composite additive BaCO3/CaO for the vanadium extraction from the refractory stone coal, the vanadium leaching effect has been investigated and many technical conditions have also been optimized. The results indicated that an optimum vanadium leaching efficiency of 81.07% can be obtained under the conditions that the mass ratio of BaCO3 to CaO was 1:9 with the total proportion of the raw ore was 5 wt.%, the roasting temperature was 850°C, the roasting time was 2 h, the sulfuric acid concentration was 15% (v/v), the leaching temperature was 95°C, the liquid-to-solid ratio was 4 mL/g, and the leaching time was 3 h. Meanwhile, the vanadium leaching mechanisms demonstrated that the composite additive BaCO3/CaO can destroy the lattice structure of muscovite and phlogopite with the production of BaSi4O9 and Ca2Al2SiO7 during the roasting process, which can therefore facilitate the release and extraction of vanadium.

  1. Imaging of Vanadium in Microfossils: A New Potential Biosignature

    Science.gov (United States)

    Marshall, Craig P.; Marshall, Alison Olcott; Aitken, Jade B.; Lai, Barry; Vogt, Stefan; Breuer, Pierre; Steemans, Philippe; Lay, Peter A.

    2017-11-01

    The inability to unambiguously distinguish the biogenicity of microfossil-like structures in the ancient rock record is a fundamental predicament facing Archean paleobiologists and astrobiologists. Therefore, novel methods for discriminating biological from nonbiological chemistries of microfossil-like structures are of the utmost importance in the search for evidence of early life on Earth. This, too, is important for the search for life on Mars by in situ analyses via rovers or sample return missions for future analysis here on Earth. Here, we report the application of synchrotron X-ray fluorescence imaging of vanadium, within thermally altered organic-walled microfossils of bona fide biological origin. From our data, we demonstrate that vanadium is present within microfossils of undisputable biological origin. It is well known in the organic geochemistry literature that elements such as vanadium are enriched and contained within crude oils, asphalts, and black shales that have been formed by diagenesis of biological organic material. It has been demonstrated that the origin of vanadium is due to the diagenetic alteration of precursor chlorophyll and heme porphyrin pigment compounds from living organisms. We propose that, taken together, microfossil-like morphology, carbonaceous composition, and the presence of vanadium could be used in tandem as a biosignature to ascertain the biogenicity of putative microfossil-like structures.

  2. Membrane development for vanadium redox flow batteries.

    Science.gov (United States)

    Schwenzer, Birgit; Zhang, Jianlu; Kim, Soowhan; Li, Liyu; Liu, Jun; Yang, Zhenguo

    2011-10-17

    Large-scale energy storage has become the main bottleneck for increasing the percentage of renewable energy in our electricity grids. Redox flow batteries are considered to be among the best options for electricity storage in the megawatt range and large demonstration systems have already been installed. Although the full technological potential of these systems has not been reached yet, currently the main problem hindering more widespread commercialization is the high cost of redox flow batteries. Nafion, as the preferred membrane material, is responsible for about 11% of the overall cost of a 1 MW/8 MWh system. Therefore, in recent years two main membrane related research threads have emerged: 1) chemical and physical modification of Nafion membranes to optimize their properties with regard to vanadium redox flow battery (VRFB) application; and 2) replacement of the Nafion membranes with different, less expensive materials. This review summarizes the underlying basic scientific issues associated with membrane use in VRFBs and presents an overview of membrane-related research approaches aimed at improving the efficiency of VRFBs and making the technology cost-competitive. Promising research strategies and materials are identified and suggestions are provided on how materials issues could be overcome.

  3. Atomic XAFS as a Tool To Probe the Reactivity of Metal Oxide Catalysts: Quantifying Metal Oxide Support Effects

    NARCIS (Netherlands)

    Keller, D.E.; Airaksinen, S.M.K.; Krause, A.O.I.; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397; Koningsberger, D.C.|info:eu-repo/dai/nl/073704342

    2007-01-01

    The potential of atomic XAFS (AXAFS) to directly probe the catalytic performances of a set of supported metal oxide catalysts has been explored for the first time. For this purpose, a series of 1 wt % supported vanadium oxide catalysts have been prepared differing in their oxidic support material

  4. Comparison of Microstructural and Tribological Effects of Low Vanadium-Low Titanium Additions to a Gray Cast Iron

    Science.gov (United States)

    Hassani, A.; Habibolahzadeh, A.; Sadeghinejad, S.

    2013-01-01

    Effects of low amounts of vanadium and titanium additions on the microstructure, tribological properties of a gray cast iron were studied and an overall comparison was made between these two alloys. Pin-on-disk tests were performed on the specimens at three different loads and two sliding speeds. SEM was utilized to study the worn surfaces and the mechanisms under which wear occurred. Local chemical analyses were conducted on the specific spots in the wear tracks by EDX. Wear mechanisms were determined and the quantitative amounts of the elements in the tribochemical films formed on the wear tracks were evaluated. Both vanadium-treated and untreated samples exhibited oxidative wear mechanism under mild regimes and adhesive wear mechanism under severe wear regime. The wear rate was reduced up to 85% when the vanadium-treated sample was tested; it showed the best wear resistance. The alloy having titanium, however, showed the least wear resistance compared to the others. It could be due to the formation of type-D graphite in its microstructure.

  5. Chromium, nickel and vanadium mobility in soils derived from fluvioglacial sands.

    Science.gov (United States)

    Agnieszka, Jeske; Barbara, Gworek

    2012-10-30

    The presented study was focused on soils developed from fluvioglacial sands from the Puszcza Borecka forest complex. The mobility of chromium, nickel and vanadium was evaluated with regard to litho- and pedogenic factors. The aim of the study was to determine with which soil constituents fractions of heavy metals are bound with particular attention drawn on the mobile fractions (F1+F2). Heavy metal fractions in the soils were determined using the sequential extraction method of Tessier et al. The purpose of sequential extraction methods to soil samples provides relevant information about possible toxicity when they are discharged into the soil environment. Chromium, nickel, and vanadium occurred predominantly in the fraction bound with iron and manganese oxides and in the residual fraction, thus showed low mobility. With regard to mobility, the elements studied can be arranged as follows: V

  6. Photolytic Release of Dissolved Vanadium and Copper from Resuspended Coastal Marine Sediments

    Science.gov (United States)

    Skrabal, S. A.; Hammaker, S. N.; McBurney, A. W.; Avery, G. B., Jr.; Kieber, R. J.; Mead, R. N.

    2016-02-01

    Sunlight photolysis engenders release of dissolved vanadium (V), copper (Cu), and dissolved organic carbon (DOC) from a wide variety of resuspendable coastal marine sediments. Net photoreleases after 6 h of simulated sunlight were as high as 12 nM for Cu and as high as 15 nM for V. Release of Cu significantly correlated with sediment Cu. Photoreleased Cu (but not V) correlated with sediment Fe content, suggesting that photoreduction of Fe oxide carrier phases may be an important photoproduction mechanism for Cu. Longer term experiments showed continued release of metals that were not immediately readsorbed back onto sediments after 24 h of irradiation suggesting that photoproduced metals persist in the dissolved phase and are not immediately scavenged onto particles. Experiments utilizing differing total suspended sediment (TSS) levels show that, although higher TSS causes more photoproduction of Cu and V, the amount produced per mass of sediment is greatest at the lowest TSS. Vanadium photoproduction increased in Macondo oil-amended sediments compared to controls after a one-month incubation period suggesting that the oil may be a source of this metal to the water column. These results imply that photoproduction is an unrecognized source of the micronutrient metals Cu and V to coastal waters.

  7. Axial coordination in nickel and vanadium porphyrins: Transient and difference raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shelnutt, J.; Alston, K.; Findsen, E.; Ondrias, M.

    1986-04-01

    Nickel and vanadium tetrapyrroles occurring in coal and petroleum are of biological origin and their present day molecular structures provide a valuable chemical fossil marker of the diagenesis of the deposits. Both Ni- and V-porphyrins add axial ligands at the metal site. The authors have investigated the equilibrium properties and nanosecond dynamics of axial ligation in Ni(II)- and V(IV)-porphyrin complexes, Ni-porphyrin-reconstituted heme proteins, and Ni-porphyrin polymers using resonance Raman spectroscopy. The state of axial coordination is recognized by characteristic frequencies of Raman oxidation-state and core-size marker lines arising from the vibrations of the porphyrin ring, and the frequencies distinguish between 4-, 5-, and 6-coordination. For the Ni-porphyrins, 4- and 6-coordinate species are observed in coordinating solvents, while 5-coordinate Ni occurs only in the protein matrix. The axial ligand-Ni stretching mode frequency is influenced by the conformation of the protein matrix. Ligand affinity is affected by porphyrin structure, ligand basicity, and the porphyrin's environment. The authors also investigated photoinduced ligand-release and ligand binding kinetics using transient Raman spectroscopy. The protein matrix has a strong influence on the kinetics of ligand rebinding. For vanadium porphyrins, similar shifts in the marker lines characterize 5- and 6-coordinate forms.

  8. Biodesulfurization of vanadium-bearing titanomagnetite concentrates and pH control of bioleaching solution

    Science.gov (United States)

    Liu, Xiao-rong; Jiang, Sheng-cai; Liu, Yan-jun; Li, Hui; Wang, Hua-jun

    2013-10-01

    Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans ( A. ferrooxidans). The sulfur content of the concentrates was reduced from 0.69wt% to 0.14wt% after bioleaching for 15 d with a 10% pulp density at 30°C. Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption, resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution. It is discovered that the citric acid-disodium hydrogen phosphate buffer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0-3.0 for A. ferrooxidans growth. Using the buffer in the volume fraction range of 5.0%-15.0% stimulates A. ferrooxidans growth and improves the biodesulfurization efficiency. Compared with the buffer-free control case, the maximum increase of biodesulfurization rate is 29.7% using a 10.0vol% buffer. Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores.

  9. Assessing the solubility controls on vanadium in groundwater, northeastern San Joaquin Valley, CA

    Science.gov (United States)

    Wright, Michael T.; Stollenwerk, Kenneth G.; Belitz, Kenneth

    2014-01-01

    The solubility controls on vanadium (V) in groundwater were studied due to concerns over possible harmful health effects of ingesting V in drinking water. Vanadium concentrations in the northeastern San Joaquin Valley ranged from 25 μg/L) and lowest in samples collected from anoxic groundwater (70% 2VO4−. Adsorption/desorption reactions with mineral surfaces and associated oxide coatings were indicated as the primary solubility control of V5+ oxyanions in groundwater. Environmental data showed that V concentrations in oxic groundwater generally increased with increasing groundwater pH. However, data from adsorption isotherm experiments indicated that small variations in pH (7.4–8.2) were not likely as an important a factor as the inherent adsorption capacity of oxide assemblages coating the surface of mineral grains. In suboxic groundwater, accurate SM modeling was difficult since Eh measurements of source water were not measured in this study. Vanadium concentrations in suboxic groundwater decreased with increasing pH indicating that V may exist as an oxycationic species [e.g. V(OH)3+]. Vanadium may complex with dissolved inorganic and organic ligands under suboxic conditions, which could alter the adsorption behavior of V in groundwater. Speciation modeling did not predict the existence of V-inorganic ligand complexes and organic ligands were not collected as part of this study. More work is needed to determine processes governing V solubility under suboxic groundwater conditions. Under anoxic groundwater conditions, SM predicts that aqueous V exists as the uncharged V(OH)3 molecule. However, exceedingly low V concentrations show that V is sparingly soluble in anoxic conditions. Results indicated that V may be precipitating as V3+- or mixed V3+/Fe3+-oxides in anoxic groundwater, which is consistent with results of a previous study. The fact that V appears insoluble in anoxic (Fe reducing) redox conditions indicates that the behavior of V is different than

  10. Direct Acid Leaching of Vanadium from Stone Coal

    Science.gov (United States)

    Zhang, Bo; Gao, Zhaoguo; Liu, Hongzhao; Wang, Wei; Cao, Yaohua

    2017-09-01

    This paper focused on optimizing the process conditions of direct acid leaching process to enhance the leaching efficiency of leaching vanadium from the stone coal. Orthogonal experiments and single factor experiments were conducted to investigate the effect of the influential factors of direct acid leaching on vanadium leaching ratio. The results showed that the vanadium leaching ratio reached the maximum value of 89.22 % under the optimal process conditions of CaF2 dosage 5 mass%, H2SO4 dosage 40 mass%, leaching temperature 95 °C and leaching time 10 h. Furthermore, the reaction mechanisms of the main influencing factors were analyzed. Finally, the two-stage counter-current leaching process was adopted to decrease the consumption of sulfuric acid and neutralizer, and the results indicated that the consumption of sulfuric acid decreased 12.50 % as well as neutralizer decreased 35.80 %.

  11. Complex research of vanadium dioxide in the homoginuity field

    Science.gov (United States)

    Surikov, Vad I.; Semenyuk, N. A.; Surikov, Val I.; Kuznetsova, Y. V.; Pavlovskaya, O. Y.

    2018-01-01

    The complex research results of vanadium dioxide VÜ2±x obtained with X-ray analysis method, a method of vacuum adiabatic calorimeter and Faraday method are discussed. The samples temperature dependences of electrical resistivity, heat capacity, and also magnetic susceptibility are presented and they prove that these characteristics jump abruptly in the phase transition area. Thermophysical, electrical, magnetic properties of vanadium dioxide are established to vary with the oxygen content in the samples. Values of Debye characteristic temperatures θD for samples VO2±x determined at temperature 150 K are presented. Values of entropy change as an amount of electronic and phonon components at phase transition were calculated. The results obtained allow to consider the phase transition of a metal semiconductor as a Mott-Peierls transition, and also to use vanadium dioxide in temperature sensors manufacture.

  12. Adsorption kinetics and isotherm of vanadium with melamine.

    Science.gov (United States)

    Peng, Hao; Liu, Zuohua; Tao, Changyuan

    2017-05-01

    Melamine, possessing three free amino groups and three aromatic nitrogen atoms in its molecule, has great potential as an adsorbent for metal ions. We investigated three impact factors of the adsorption process: the initial pH of the vanadium solution, contact time and reaction temperature. The adsorption kinetics could be accurately described by the pseudo-second-order kinetic model. Langmuir and Freundlich models fitted well with the experimental equilibrium data, and the maximal adsorption capacity was found to be 1,428.57 mg vanadium/g melamine, and the Freundlich model showed the adsorption is privilege type.

  13. Flowerlike vanadium sesquioxide: solvothermal preparation and electrochemical properties.

    Science.gov (United States)

    Liu, Haimei; Wang, Yonggang; Li, Huiqiao; Yang, Wensheng; Zhou, Haoshen

    2010-10-25

    A novel 3D hierarchical flowerlike vanadium sesquioxide (V(2)O(3)) nano/microarchitecture consisting of numerous nanoflakes is prepared via a solvothermal approach followed by an appropriate heating treatment. The as-obtained nanostructured V(2)O(3) flower is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and transmission electron microscopy (TEM) (or/and high-resolution TEM, HRTEM), and it is found that the V(2)O(3) flower is constructed by single-crystalline nanoflakes. Furthermore, it is demonstrated that the surface of the flowerlike V(2)O(3) material is composed of nanostructured pores, which derive from the adsorption/desorption of nitrogen, and that the pore-size distribution depends on the unique three-dimensional interconnection between nanoflakes and on their intrinsic properties. The electrochemical behavior of the V(2)O(3) flower for lithium-ion insertion/extraction in non-aqueous solution as well as the faradaic capacitance for pesudocapacitors in a neutral aqueous solution are also investigated. A reversible discharge capacity as high as 325 mA h g(-1) is obtained at a current density of 0.02 A g(-1) from a LiClO(4)/EC:DEC electrolyte solution (i.e. LiClO(4) in ethyl carbonate and diethyl carbonate). When used as the cathode material of pesudocapacitors in Li(2)SO(4), the flowerlike oxide displayed a very high initial capacitance of 218 F g(-1) at a current density of 0.05 A g(-1). We believe that the good performance of the flowerlike V(2)O(3) electrode is most probably due to its unique 3D hierarchical nano/microarchitecture, which shows that the electrochemical properties of a cathodic material do not only depend on the oxidation state of that material but also-to a large extent-on its crystalline structure and morphology. The aforementioned properties suggest that the present V(2)O(3) flower materials may have a great potential to be employed as electrode materials in

  14. Absorption of hydrogen in vanadium, enhanced by ion bombardment; Ionenbeschussunterstuetzte Absorption des Wasserstoffs in Vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Paulus, H.; Lammers, M. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany); Mueller, K.H. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany)]|[Paderborn Univ. (Gesamthochschule), Soest (Germany). Fachbereich 16 - Elektrische Energietechnik; Kiss, G.; Kemeny, Z. [Technical Univ. Budapest (Hungary)

    1998-12-31

    Prior to hydrogen implantation into vanadium, the vanadium specimen usually is exposed to an activation process and is then heated at 1 atm hydrogen to temperatures between 500 and 600 C, subsequently cooled down in several steps. Within this temperature range, hydrogen solubility increases with declining temperature. A decisive factor determining hydrogen absorption is the fact that at temperatures above 250 C, oxygen desorbs from the material surface and thus no longer inhibits hydrogen absorption. Therefore a different approach was chosen for the experiments reported: Hydrogen absorption under UHV conditions at room temperature. After the usual activation process, the vanadium surface was cleaned by 5 keV Ar{sup +} ion bombardment. Thus oxygen absorption at the specimen surface (and new reactions with oxygen from the remaining gas) could be avoided, or removed. By means of thermal desorption mass spectrometry (TDMS), hydrogen absorption as a function of argon ion dose was analysed. TDMS measurements performed for specimens treated by ion bombardment prior to H{sup 2} exposure showed two H{sup 2} desorption peaks, in contrast to the profiles measured with specimens not exposed to ion bombardment. It is assumed that the ion bombardment disturbs the crystal structure so that further sites for hydrogen absorption are produced. (orig./CB) [Deutsch] Bei der Beladung von Vandium mit Wasserstoff wird ueblicherweise die Probe nach einer Aktivierungsprozedur bei 1 atm Wasserstoff auf Temperaturen im Bereich von 500 bis 600 C hochgeheizt und danach schrittweise abgekuehlt. In diesem Temperaturbereich nimmt die Wasserstoffloeslichkeit mit abnehmender Temperatur zu. Entscheidend fuer die Beladung ist aber auch die Tatsache, dass bei Temperaturen groesser 250 C Sauerstoff von der Oberflaeche desorbiert und dadurch die Absorption von Wasserstoff nicht mehr blockieren kann. Im Rahmen der hier beschriebenen Untersuchungen sollte die Wasserstoffbeladung unter UHV-Bedingungen bei

  15. Carbon-carbon bond cleavage of 1,2-hydroxy ethers b7 vanadium(V) dipicolinate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Susan K [Los Alamos National Laboratory; Gordon, John C [Los Alamos National Laboratory; Thorn, David L [Los Alamos National Laboratory; Scott, Brian L [Los Alamos National Laboratory; Baker, R Tom [Los Alamos National Laboratory

    2009-01-01

    The development of alternatives to current petroleum-based fuels and chemicals is becoming increasingly important due to concerns over climate change, growing world energy demand, and energy security issues. Using non-food derived biomass to produce renewable feedstocks for chemicals and fuels is a particularly attractive possibility. However, the majority of biomass is in the form of lignocellulose, which is often not fully utilized due to difficulties associated with breaking down both lignin and cellulose. Recently, a number of methods have been reported to transform cellulose directly into more valuable materials such as glucose, sorbitol, 5-(chloromethyl)furfural, and ethylene glycol. Less progress has been made with selective transformations of lignin, which is typically treated in paper and forest industries by kraft pulping (sodium hydroxide/sodium sulfide) or incineration. Our group has begun investigating aerobic oxidative C-C bond cleavage catalyzed by dipicolinate vanadium complexes, with the idea that a selective C-C cleavage reaction of this type could be used to produce valuable chemicals or intermediates from cellulose or lignin. Lignin is a randomized polymer containing methoxylated phenoxy propanol units. A number of different linkages occur naturally; one of the most prevalent is the {beta}-O-4 linkage shown in Figure 1, containing a C-C bond with 1,2-hydroxy ether substituents. While the oxidative C-C bond cleavage of 1,2-diols has been reported for a number of metals, including vanadium, iron, manganese, ruthenium, and polyoxometalate complexes, C-C bond cleavage of 1,2-hydroxy ethers is much less common. We report herein vanadium-mediated cleavage of C-C bonds between alcohol and ether functionalities in several lignin model complexes. In order to explore the scope and potential of vanadium complexes to effect oxidative C-C bond cleavage in 1,2-hydroxy ethers, we examined the reactivity of the lignin model complexes pinacol monomethyl ether (A

  16. Optimal Location of Vanadium in Muscovite and Its Geometrical and Electronic Properties by DFT Calculation

    Directory of Open Access Journals (Sweden)

    Qiushi Zheng

    2017-02-01

    Full Text Available Vanadium-bearing muscovite is the most valuable component of stone coal, which is a unique source of vanadium manufacture in China. Numbers of experimental studies have been carried out to destroy the carrier muscovite’s structure for efficient extraction of vanadium. Hence, the vanadium location is necessary for exploring the essence of vanadium extraction. Although most infer that vanadium may substitute for trivalent aluminium (Al as the isomorphism in muscovite for the similar atomic radius, there is not enough experimental evidence and theoretical supports to accurately locate the vanadium site in muscovite. In this study, the muscovite model and optimal location of vanadium were calculated by density functional theory (DFT. We find that the vanadium prefers to substitute for the hexa-coordinated aluminum of muscovite for less deformation and lower substitution energy. Furthermore, the local geometry and relative electronic properties were calculated in detail. The basal theoretical research of muscovite contained with vanadium are reported for the first time. It will make a further influence on the technology development of vanadium extraction from stone coal.

  17. Comparison of vanadium-rich activity of three species fungi of basidiomycetes.

    Science.gov (United States)

    Han, Chunchao; Cui, Bo; Qu, Jingran

    2009-03-01

    A comparison of vanadium-rich activity of three species fungi of Basidiomycetes, Ganoderma lucidum, Coprinus comatus, and Grifola frondosa, was studied. By fermentation and atomic absorption spectroscopy analysis, the biomass of G. lucidum and G. frondosa declined rapidly when the concentration of vanadium exceeded 0.3% but the biomass of C. comatus did not decline rapidly until the concentration of vanadium exceeded 0.4% and the content of vanadium accumulated in the mycelia was 3529.3 microg/g. After the mice were administered (intragastrically) with vanadium-rich C. comatus, the blood glucose of alloxan-induced hyperglycemic mice was decreased (p comatus to absorb vanadium and chose 0.4% as the optimal concentration of vanadium for the pharmacological works.

  18. The Content of Vanadium in the Egg of the Ascidian, Halocynthia roretzi and Its Changes during the Development

    OpenAIRE

    堀, 令司; 沼宮内, 隆晴; 道端, 斉; Reiji, Hori; Takaharu, Numakunai; Hitoshi, Michibata; 東北大学理学部付属浅虫臨海実験所; 富山大学理学部生物学教室; Asamushi marine biological station, Tohoku University; Biological Institute, Faculty of Science, University of Kanazawa

    1981-01-01

    The vanadium content of the egg and embryo of the ascidian, Halocynthia roretzi was determined by activation analysis. The content of vanadium in an egg remained unchanged during the cleavage. A remarkable increase in the amount of vanadium in the embryo was observed during metamorphosis. Vanadium content in the larva one year after spawning amounted to about 820,000 times of that of the unfertilized egg. The accumulation of vanadium by the ascidian was discussed in comparison with phosphorus.

  19. On the layer structure of vanadium pentoxide gels. Comment on `molecular dynamic simulation of the vanadium pentoxide gel host`

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Takeshi [Department of Fundamental Energy Science, Graduate School of Energy Sciences, Kyoto University, Kyoto (Japan); Oka, Yoshio [Department of Natural Environment Sciences, Faculty of Integrated Human Studies, Kyoto University, Kyoto (Japan)

    1997-04-16

    A comment on the article entitled `molecular dynamic simulation of the vanadium pentoxide gel host` [J. Linde and J.O. Thomas, Solid State Ionics 85 (1996) 1] is presented concerning the model structure of the V{sub 2}O{sub 5} layer of vanadium pentoxide gels. The double-layer structure used in the simulation was derived from the crystalline V{sub 2}O{sub 5}. This model structure significantly differs from the double-sheet type determined by the X-ray Rietvelt method. The simulation should be recalculated based on the double-sheet type V{sub 2}O{sub 5} layer

  20. Effects of Microwave Roasting on the Kinetics of Extracting Vanadium from Vanadium Slag

    Science.gov (United States)

    Zhang, Guoquan; Zhang, Ting-an; Lü, Guozhi; Zhang, Ying; Liu, Yan; Zhang, Weiguang

    2016-02-01

    The kinetics of extracting vanadium (V) from microwave-roasted (MR) vanadium slag (V-slag) with concentrated H2SO4 were investigated. The microwave irradiation experiments were performed in a modified microwave muffle furnace at temperatures ranging from 150°C to 750°C. The x-ray diffraction analysis indicated that the spinel phase of the V-slag is destroyed after 10 min of roasting. The phase composition of the V-slag was changed by the roasting process, and a new Fe2O3 phase appeared in the samples roasted at higher temperatures. Compared to the raw slag, the surface area, pore volume, and pore size of the MR slags were much lower. It was easier to leach V from the MR samples than the raw sample with the H2SO4 solution, and the leaching process was accelerated in the MR samples. When the V-slag was roasted at 150°C and 350°C (MR@150 and MR@350, respectively), the apparent activation energy was decreased from 77.65 kJ/mol to 68.42 kJ/mol and 66.68 kJ/mol, respectively. The process of leaching V from the raw and MR slags was controlled by both the surface chemical reactions and internal diffusion. The reaction orders of the raw, MR@150, and MR@350 V-slags, with respect to the H2SO4 concentration, were 1.23, 0.75, and 0.70, respectively.

  1. Facile embedding of single vanadium atoms at the anatase TiO2(101) surface.

    Science.gov (United States)

    Koust, Stig; Arnarson, Logi; Moses, Poul G; Li, Zheshen; Beinik, Igor; Lauritsen, Jeppe V; Wendt, Stefan

    2017-04-05

    To understand the structure-reactivity relationships for mixed-metal oxide catalysts, well-defined systems are required. Mixtures of vanadia and titania (TiO 2 ) are of particular interest for application in heterogeneous catalysis, with TiO 2 often acting as the support. By utilizing high-resolution scanning tunneling microscopy, we studied the interaction of vanadium (V) with the anatase TiO 2 (101) surface in the sub-monolayer regime. At 80 K, metallic V nucleates into homogeneously distributed clusters onto the terraces with no preference for nucleation at the step edges. However, embedding of single V atoms into TiO 2 occurs following annealing at room temperature. In conjunction with X-ray photoelectron spectroscopy data and density functional theory calculations, we propose that monomeric V atoms occupy positions of regular surface Ti sites, i.e., Ti atoms are substituted by V atoms.

  2. Coupling Reactions of Carbon Dioxide with Epoxides Catalyzed by Vanadium Aminophenolate Complexes.

    Science.gov (United States)

    Elkurtehi, Ali I; Kerton, Francesca M

    2017-03-22

    A series of vanadium compounds supported by tetradentate aminobis(phenolate) ligands were screened for catalytic reactivity in the reaction of propylene oxide (PO) with CO2 : [VO(OMe)(O2 NOBuMeMeth )], [VO(OMe)(ON2 OBuMe )], [VO(OMe)(O2 NNBuBuPy )], and [VO(OMe)(O2 NOBuBuFurf )]. They showed similar reactivities, but reaction rates were higher for [VO(OMe)(ON2 OBuMe )], which was studied in more detail. Turnover frequencies for conversion of PO over 500 h-1 were observed. Activation energies were determined experimentally through in situ IR spectroscopy for propylene carbonate (48.2 kJ mol-1 ), styrene carbonate (45.6 kJ mol-1 ), and cyclohexene carbonate (54.7 kJ mol-1 ) formation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Transparent optically vanadium dioxide thermochromic smart film fabricated via electrospinning technique

    Science.gov (United States)

    Lu, Yuan; Xiao, Xiudi; Cao, Ziyi; Zhan, Yongjun; Cheng, Haoliang; Xu, Gang

    2017-12-01

    The monoclinic phase vanadium dioxide VO2 (M) based transparent thermochromic smart films were firstly fabricated through heat treatment of opaque VO2-based composite nanofibrous mats, which were deposited on the glass substrate via electrospinning technique. Noteworthily, the anti-oxidation property of VO2 smart film was improved due to inner distribution of VO2 in the polymethylmethacrylate (PMMA) nanofibers, and the composite mats having water contact angle of 165° determined itself good superhydrophobic property. Besides, PMMA nanofibrous mats with different polymer concentrations demonstrated changeable morphology and fiber diameter. The VO2 nanoparticles having diameter of 30-50 nm gathered and exhibited ellipse-like or belt-like structure. Additionally, the solar modulation ability of PMMA-VO2 composite smart film was 6.88% according to UV-Vis-NIR spectra. The research offered a new notion for fabricating transparent VO2 thermochromic material.

  4. The role of vanadium haloperoxidases in the formation of volatile brominated compounds and their impact on the environment.

    Science.gov (United States)

    Wever, Ron; van der Horst, Michael A

    2013-09-07

    Vanadium haloperoxidases differ strongly from heme peroxidases in substrate specificity and stability and in contrast to a heme group they contain the bare metal oxide vanadate as a prosthetic group. These enzymes specifically oxidize halides in the presence of hydrogen peroxide into hypohalous acids. These reactive halogen intermediates will react rapidly and aspecifically with many organic molecules. Marine algae and diatoms containing these iodo- and bromoperoxidases produce short-lived brominated methanes (bromoform, CHBr3 and dibromomethane CH2Br2) or iodinated compounds. Some seas and oceans are supersaturated with these compounds and they form an important source of bromine to the troposphere and lower stratosphere and contribute significantly to the global budget of halogenated hydrocarbons. This perspective focuses, in particular, on the biosynthesis of these volatile compounds and the direct or indirect involvement of vanadium haloperoxidases in the production of huge amounts of bromoform and dibromomethane. Some of the global sources are discussed and from the literature a picture emerges in which oxidized brominated species generated by phytoplankton, seaweeds and cyanobacteria react with dissolved organic matter in seawater, resulting in the formation of intermediate brominated compounds. These compounds are unstable and decay via a haloform reaction to form an array of volatile brominated compounds of which bromoform is the major component followed by dibromomethane.

  5. Vanadium, rubidium and potassium in Octopus vulgaris (Mollusca: Cephalopoda

    Directory of Open Access Journals (Sweden)

    Sónia Seixas

    2005-06-01

    Full Text Available The levels of vanadium, rubidium and potassium were determined in Octopus vulgaris caught during commercial fishing activities at three locations (Cascais, Santa Luzia and Viana do Castelo in Portugal in autumn and spring. We determined the concentration of these elements in digestive gland, branchial heart, gills, mantle and arms in males and females. At least five males and five females were assessed for each season/location combination. Elemental concentrations were determined by Particle Induced X-ray Emission (PIXE. Vanadium was detectable only in digestive gland and branchial heart samples. Its concentration was not correlated with total weight, total length or mantle length. There were no differences in concentrations of V, Rb and K between sexes. There were significant differences in vanadium concentrations in branchial hearts in autumn between samples from Viana do Castelo and those from the other two sites. We found a significant positive relationship between the concentration of vanadium and those of potassium and rubidium in branchial hearts. Branchial hearts appear to play an important role in decontamination of V.

  6. Halofunctionalization of alkenes by vanadium chloroperoxidase from Curvularia inaequalis

    NARCIS (Netherlands)

    Dong, J.; Fernandez Fueyo, E.; Li, Jingbo; Guo, Zheng; Renirie, Rokus; Wever, Ron; Hollmann, F.

    The vanadium-dependent chloroperoxidase from Curvularia inaequalis is a stable and efficient biocatalyst for the hydroxyhalogenation of a broad range of alkenes into halohydrins. Up to 1 200 000 TON with 69 s−1 TOF were observed for the biocatalyst. A bienzymatic cascade to yield epoxides as

  7. Combined effect of vanadium and nickel on lipid peroxidation and ...

    African Journals Online (AJOL)

    In this investigation, hepatorenal antioxidant effects of combined oral administration of ammonium metavanadate (AMV; 0.15 mg V/ml) and nickel sulfate (NS; 0.18 mg Ni/ml) in male albino rats over a 21- day period have been evaluated. After administration of vanadium, lipid peroxidation (LPO) increased significantly (p ...

  8. TWO LIGAND OXIDIO-VANADIUM(IV) COMPLEXES AS NOVEL ...

    African Journals Online (AJOL)

    TWO LIGAND OXIDIO-VANADIUM(IV) COMPLEXES AS NOVEL EFFICIENT. CATALYSTS IN MULTICOMPONENT REACTIONS FOR SYNTHESIS OF. TETRAHYDROBENZOPYRAN DERIVATIVES. Mehdi Abaszadeh1,2*, Mohammad Seifi3 and S. Yousef Ebrahimipour 4,5. 1Pharmaceutics Research Center, Institute of ...

  9. Neurotoxic profiles of vanadium when administered at the onset of ...

    African Journals Online (AJOL)

    Further “immune” assays revealed astrocytic activation (GFAP stain), demyelination (CNPase) and activated microglia (Iba1) due to vanadium which were ameliorated by the administration of vit E to the dams. The pups whose dams were administered with vit E alone showed signs of cellular degeneration which might be ...

  10. Electrochemical properties of dip-coated vanadium pentaoxide thin ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 6. Electrochemical properties of dip-coated vanadium pentaoxide thin films. R S INGOLE B J LOKHANDE. Volume 39 Issue 6 ... Author Affiliations. R S INGOLE1 B J LOKHANDE1. School of Physical Sciences, Solapur University, Solapur 413 255, India ...

  11. Excimer laser reactive deposition of vanadium nitride thin films

    Science.gov (United States)

    D'Anna, E.; Di Cristoforo, A.; Fernández, M.; Leggieri, G.; Luches, A.; Majni, G.; Mengucci, P.; Nanai, L.

    2002-01-01

    We report on the deposition of thin vanadium nitride films by ablating vanadium targets in low-pressure N 2 atmosphere, and on their characterization. The targets were vanadium foils (purity 99.8%). 3 in. Si(1 1 1) wafers were used as substrates. Film characteristics (composition and crystalline structure) were studied as a function of N 2 pressure (0.5-200 Pa), KrF laser fluence (4.5-19 J/cm 2), substrate temperature (20-750 °C) and target-to-substrate distance (30-70 mm). Vanadium nitride is already formed at low N 2 ambient pressures (1 Pa) and laser fluences (6 J/cm 2) on substrates at room temperature. At the N 2 pressures of 1-10 Pa, the prevalent phase is VN. At higher pressures (100 Pa) and at relatively high laser fluences (16-19 J/cm 2), the dominant phase is V 2N. The crystallinity of the films improves by increasing the substrate temperature. Well-crystallized films are obtained on substrates heated at 500 °C.

  12. A model approach to vanadium involvement in crude oil refining

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    The research during the last nine months has continued with the overall goal of developing V/S chemistry and has been concentrated on the two main areas of the project: the reactivity chemistry of vanadyl complexes, and the development of sulfide-bridged vanadium cluster chemistry. Significant new progress has been achieved in both these areas.

  13. Vanadium Effect on a Medium Carbon Forging Steel

    Directory of Open Access Journals (Sweden)

    Carlos Garcia-Mateo

    2016-05-01

    Full Text Available In the present work the influence of vanadium on the hardenability and the bainitic transformation of a medium carbon steel is analyzed. While V in solid solution enhances the former, it hardly affects bainitic transformation. The results also reveal an unexpected result, an increase of the prior austenite grain size as the V content increases.

  14. determination of vanadium in foods by atomic absorption spectrometry

    African Journals Online (AJOL)

    This paper presents an assessment of the level of vanadium in foods (Plantain, Musa spp; Yam, Discorea rotundata; and Maize, Zea mays) from ten popular market places in Lagos metropolis, Nigeria. Total acid leaching digestion method was employed and determination was by Flame Atomic Absorption ...

  15. Effects of Vanadium Pentoxide on the Histological and Sperm ...

    African Journals Online (AJOL)

    The pharmacological effects of intraperitoneal administration of different doses of vanadium pentoxide (V2O5) on the histological and sperm parameters of male guinea pigs were investigated. Also investigated were the effects of oral pretreatment with different doses of vitamin E (a known protein kinase C inhibitor) on the ...

  16. Speciation of Chromium and Vanadium in Medicinal Plants

    African Journals Online (AJOL)

    NICOLAAS

    Results of the determination of water-soluble (hot water) Cr(VI) and V(V) concentrations ... tive and purging gas. 2.2. Quality Assurance. The analytical results for the determination of chromium and vanadium were validated through the analysis of certified refer- ... were filtered through 0.45 µm hydrophilic PVDF filter prior the.

  17. The ternary system: silicon-uranium-vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Noel, Henri [Laboratoire de Chimie du Solide et Materiaux, UMR-CNRS 6226, Universite de Rennes I, Avenue du General Leclerc, F-35042 Rennes, Cedex (France); Rogl, Peter Franz, E-mail: peter.franz.rogl@univie.ac.a [Institute of Physical Chemistry, University of Vienna, A-1090 Wien, Waehringerstrasse 42 (Austria)

    2010-09-01

    Phase equilibria in the system Si-U-V were established at 1100 {sup o}C by optical microscopy, EMPA and X-ray diffraction. Two ternary compounds were observed, U{sub 2}V{sub 3}Si{sub 4} and (U{sub 1-x}V{sub x}){sub 5}Si{sub 3}, for which the crystal structures were elucidated by X-ray powder data refinement and found to be isotypic with the monoclinic U{sub 2}Mo{sub 3}Si{sub 4}-type (space group P2{sub 1}/c; a = 0.6821(3), b = 0.6820(4), c = 0.6735(3) nm, {beta} = 109.77(1){sup o}) and the tetragonal W{sub 5}Si{sub 3}-type (space group I4/mcm, a = 1.06825(2), c = 0.52764(2) nm), respectively. (U{sub 1-x}V{sub x}){sub 5}Si{sub 3} appears at 1100 {sup o}C without any significant homogeneity region at x {approx} 0.2 resulting in a formula U{sub 4}VSi{sub 3} which corresponds to a fully ordered atom arrangement. DTA experiments clearly show decomposition of this phase above 1206 {sup o}C revealing a two-phase region U{sub 3}Si{sub 2} + V{sub 3}Si. At 1100 {sup o}C U{sub 4}VSi{sub 3} is in equilibrium with V{sub 3}Si, V{sub 5}Si{sub 3}, U{sub 3}Si{sub 2} and U(V). At 800 {sup o}C U{sub 4}VSi{sub 3} forms one vertex of the tie-triangle to U{sub 3}Si and V{sub 3}Si. Due to the rather high thermodynamic stability of V{sub 3}Si and the corresponding tie-lines V{sub 3}Si + liquid at 1100 {sup o}C and V{sub 3}Si + U(V) below 925 {sup o}C, no compatibility exists between U{sub 3}Si or U{sub 3}Si{sub 2} and vanadium metal.

  18. Kinetic-spectrophotometric determination of trace amounts of vanadium(V) based on its catalytic effect on the reaction of DBM-arsenazo and potassium bromate

    Science.gov (United States)

    Zhai, Qing-zhou; Zhang, Xiao-xia; Huang, Chong

    2008-03-01

    A simple and sensitive kinetic-spectrophotometric method is developed for the determination of trace vanadium(V), based on the catalytic effect of vanadium(V) on the oxidation of DBM-arsenazo by potassium bromate in 0.0138 mol l -1 phosphoric acid medium and at 100 °C in the presence of citric acid as activator. The absorbance is measured at 528 nm with the fixed-time method. The optimization of the operating conditions regarding concentrations of the reagents, temperature and interferences are also investigated. The working curve is linear over the concentration range 0-20 ng ml -1 of vanadium(V) with good precision and accuracy and the detection limit was down to 3.44 ng l -1. The relative standard deviation for a standard solution of 14 ng ml -1 is 0.28% ( n = 11). The apparent activity energies of the catalytic reaction and the non-catalytic reaction are 73.48, 113.5 kJ/mol, respectively. The proposed method proved highly sensitive, selective and relatively rapid for the assay of vanadium at low-level range of 0-20 ng ml -1 without any pre-concentration step. Thw method was applied to the determination of vanadium(V) in steels, rice, flour, cabbage, potato, fish, shrimp and tea samples with satisfactory results. The obtained results for the steel samples were excellent agreement with the standard reference values. The analytical results of the rice, flour, cabbage, potato, fish, shrimp and tea samples were excellent agreement with those of atomic absorption spectrometry. The recovery experiments have been made for the rice, flour, cabbage, potato, fish, shrimp and tea samples except the steels; excellent results were obtained. The relative standard deviations were over the range of 0.18-2.60% and the recoveries were over the range of 98.00-102.4%, respectively. The analytical results obtained were satisfactory.

  19. A novel comprehensive utilization of vanadium slag: As gamma ray shielding material

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Mengge [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Xue, Xiangxin, E-mail: xuexx@mail.neu.edu.cn [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Yang, He; Liu, Dong [School of Metallurgy, Northeastern University, Shenyang 110004 (China); Liaoning Key Laboratory of Metallurgical Resources Recycling Science, Shenyang 110004 (China); Wang, Chao [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Zhefu [Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2016-11-15

    Highlights: • A novel comprehensive utilization method for vanadium slag is proposed. • Shielding properties of vanadium slag are better than ordinary concrete. • HVL of vanadium slag is between Lead and concrete to shield {sup 60}Co gamma ray. • HVL of composite is higher than concrete when adding amount of vanadium slag is 900. • Composite can be used as injecting mortar for cracks developed in concrete shields. - Abstract: New exploration of vanadium slag as gamma ray shielding material was proposed, the shielding properties of vanadium slag was higher than concrete when the energy of photons was in 0.0001 MeV–100000 MeV. Vanadium slag/epoxy resin composites were prepared, shielding and material properties of materials were tested by {sup 60}Co gamma ray, simultaneous DSC-TGA, electronic universal testing machine and scanning electron microscopy, respectively. The results showed that the shielding properties of composite would be better with the increase of vanadium slag addition amount. The HVL (half value layer thickness) of vanadium slag was between Lead and concrete while composite was higher than concrete when the addition amount of vanadium slag was 900 used as material to shield {sup 60}Co gamma ray, also the resistance temperature of composite was about 215 °C and the bending strength was over 10 MPa. The composites could be used as injecting mortar for cracks developed in biological concrete shields, coating for the floor of the nuclear facilities, and shielding materials by itself.

  20. The role of phosphate additive in stabilization of sulphuric-acid-based vanadium(V) electrolyte for all-vanadium redox-flow batteries

    Science.gov (United States)

    Roznyatovskaya, Nataliya V.; Roznyatovsky, Vitaly A.; Höhne, Carl-Christoph; Fühl, Matthias; Gerber, Tobias; Küttinger, Michael; Noack, Jens; Fischer, Peter; Pinkwart, Karsten; Tübke, Jens

    2017-09-01

    Catholyte in all-vanadium redox-flow battery (VRFB) which consists of vanadium salts dissolved in sulphuric acid is known to be stabilized by phosphoric acid to slow down the thermal aging at temperatures higher than 40 °C. To reveal the role of phosphoric acid, the thermally-induced aggregation is investigated using variable-temperature 51V, 31P, 17O, 1H nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering (DLS). The results indicate that the thermal stabilization of vanadium(V) electrolyte is attained by the involvement of monomeric and dimeric vanadium(V) species in the reaction with phosphoric acid which is concurrent to the formation of neutral hydroxo-aqua vanadium(V) precipitation precursor. The dimers are stabilized by counter ions due to association reaction or if such stabilization is not possible, precipitation of vanadium pentoxide is favored. The evolution of particles size distributions at 50 °C in electrolyte samples containing 1.6 M vanadium and 4.0 M total sulphate and the pathways of precipitate formation are discussed. The optimal total phosphate concentration is found to be of 0.15 M. However, the induction time is assumed to be dependent not only on the total phosphate concentrations, but also on the ratio of total vanadium(V) to sulphate concentrations.

  1. Selective oxidations on vanadiumoxide containing amorphous mixed oxides (AMM-V) with tert.-butylhydroperoxide

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Y.; Hunnius, M.; Storck, S.; Maier, W.F. [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)

    1998-12-31

    The catalytic oxygen transfer properties of vanadium containing zeolites and vanadium based sol-gel catalysts with hydrogen peroxides are well known. The severe problem of vanadium leaching caused by the presence of the by-product water has been addressed. To avoid any interference with homogeneously catalyzed reactions, our study focusses on selective oxidations in a moisture-free medium with tert.-butylhydroperoxide. We have investigated the catalytic properties of amorphous microporous materials based on SiO{sub 2}, TiO{sub 2}, ZrO{sub 2} and Al{sub 2}O{sub 3} as matrix material and studied the effects of surface polarity on the oxidation of 1-octene and cyclohexane. (orig.)

  2. Influence of vanadium doping on the electrochemical behaviour of MnO{sub 2} rutile; Influence du dopage par le vanadium sur le comportement electrochimique de MnO{sub 2} rutile

    Energy Technology Data Exchange (ETDEWEB)

    Delmas, C. [Centre National de la Recherche Scientifique (CNRS), 33 - Pessac (France). Institut de Chimie de la Matiere Condensee de Bordeaux; Capitaine, F.; Majastre [Bollore Technologies, 29 - Quimper (France); Baudry, P. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches

    1996-12-31

    Vanadium doped manganese bi-oxide has been obtained from a solution containing both cations. The X-ray diffraction of this material indicates a rutile-type phase but the enlargement of some lines supports the existence of several lattice defects. Also the particle size of the doped material is significantly smaller than the one of the non-doped material obtained in the same conditions. The presence of pentavalent vanadium inside the lattice leads to a small amount of trivalent manganese. Electron microscopy shows the existence of defects which have a tendency of becoming well-ordered and to stabilize a sur-structure. At ambient temperature, the electrochemical behaviour of doped manganese bi-oxide is greatly improved when compared to the non-doped phase. This behaviour is due to the presence of numerous lattice defects and to the smaller size of crystallites. In polymer batteries, the behaviour is similar the one of the non-doped material for which the kinetics performances are improved by the cycling at 100 deg. C. Abstract only. (J.S.)

  3. DFT Studies on the Mechanism of the Vanadium-Catalyzed Deoxydehydration of Diols.

    Science.gov (United States)

    Galindo, Agustín

    2016-03-07

    The mechanism of the vanadium-catalyzed deoxydehydration of glycols to alkenes by phosphanes (Chapman, G.; Nicholas, K. M. Chem. Commun. 2013, 49, 8199-8201) has been investigated with density functional calculations. Two alternative pathways, A and B, have been evaluated, and the three stages generally recognized in DODH processes have been identified: (i) activation of the diol by condensation on the vanadium complex and eventual formation of vanadium-glycolate, (ii) oxygen atom transfer to phosphane with reduction to a vanadium(III) species, and, finally, (iii) alkene extrusion from the vanadium-glycolate with regeneration of the starting catalyst. Pathway B, in which the reduction by the phosphane from vanadium(V) to V(III) species occurred before the diol condensation, is energetically preferred to pathway A, in which the diol activation preceded the oxo-transfer to the phosphane reductant.

  4. Investigation on the oxidation behavior of AlCrVxN thin films by means of synchrotron radiation and influence on the high temperature friction

    Science.gov (United States)

    Tillmann, Wolfgang; Kokalj, David; Stangier, Dominic; Paulus, Michael; Sternemann, Christian; Tolan, Metin

    2018-01-01

    Friction minimization is an important topic which is pursued in research and industry. In addition to the use of lubricants, friction-reducing oxide phases can be utilized which occur during. These oxides are called Magnéli phases and especially vanadium oxides exhibit good friction reducing properties. Thereby, the lubrication effect can be traced back to oxygen deficiencies. AlCrN thin films are being used as coatings for tools which have to withstand high temperatures. A further improvement of AlCrN thin films concerning their friction properties is possible by incorporation of vanadium. This study analyzes the temperature dependent oxidation behavior of magnetron sputtered AlCrVN thin films with different vanadium contents up to 13.5 at.-% by means of X-ray diffraction and X-ray absorption near-edge spectroscopy. Up to 400 °C the coatings show no oxidation. A higher temperature of 700 °C leads to an oxidation and formation of Magnéli phases of the coatings with vanadium contents above 10.7 at.-%. Friction coefficients, measured by ball-on-disk test are correlated with the oxide formation in order to figure out the effect of vanadium oxides. At 700 °C a decrease of the friction coefficient with increasing vanadium content can be observed, due to the formation of VO2, V2O3 and the Magnéli phase V4O7.

  5. Determination of vanadium in refractory metals, steel, cast iron, alloys and silicates by extraction of an NBPHA complex from a sulphuric-hydrofluoric acid medium.

    Science.gov (United States)

    Donaldson, E M

    1970-07-01

    A method for determining up to 0.15% of vanadium in high-purity niobium and tantalum metals, cast iron, steel, non-ferrous alloys and silicates is described. The proposed method is based on the extraction of a red vanadium(V)-N-benzoyl-N-phenylhydroxylamine complex into chloroform from a sulphuric-hydrofluoric acid medium containing excess of ammonium persulphate as oxidant. The molar absorptivity of the complex is 428 l.mole(-1).mm(-5) at 475 nm, the wavelength of maximum absorption. Interference from chromium(VI) and cerium(IV) is eliminated by reduction with iron(II). Common ions, including large amounts of titanium, zirconium, molybdenum and tungsten, do not interfere.

  6. Macromolecular peroxo complexes of Vanadium (V) and ...

    Indian Academy of Sciences (India)

    Macromolecular metal complexes; peroxovanadates; peroxomolybdates; enzyme inhibitors; polymer-supported metal catalysts; bromoperoxidases. ... activity with phosphohydrolase enzyme vis-à-vis free peroxovanadium (pV) or peroxomolybdenum (pMo) complexes, and their activity in biomimetic oxidative bromination ...

  7. Reactivity of recombinant and mutant vanadium bromoperoxidase from the red alga Corallina officinalis.

    Science.gov (United States)

    Carter, Jayme N; Beatty, Kimberly E; Simpson, Matthew T; Butler, Alison

    2002-07-25

    Vanadium bromoperoxidase (VBPO) from the marine red alga Corallina officinalis has been cloned and heterologously expressed in Esherichia coli. The sequence for the full-length cDNA of VBPO from C. officinalis is reported. Steady state kinetic analyses of monochlorodimedone bromination reveals the recombinant enzyme behaves similarly to native VBPO from the alga. The kinetic parameters (K(m)(Br-)=1.2 mM, K(m)(H(2)O(2))=17.0 microM) at the optimal pH 6.5 for recombinant VBPO are similar to reported values for enzyme purified from the alga. The first site-directed mutagenesis experiment on VBPO is reported. Mutation of a conserved active site histidine residue to alanine (H480A) results in the loss of the ability to efficiently oxidize bromide, but retains the ability to oxidize iodide. Kinetic parameters (K(m)(I-)=33 mM, K(m)(H(2)O(2))=200 microM) for iodoperoxidase activity were determined for mutant H480A. The presence of conserved consensus sequences for the active sites of VBPO from marine sources shows its usefulness in obtaining recombinant forms of VBPO. Furthermore, mutagenesis of the conserved extra-histidine residue shows the importance of this residue in the oxidation of halides by hydrogen peroxide.

  8. An optimised sequential extraction scheme for the evaluation of vanadium mobility in soils.

    Science.gov (United States)

    Xu, Yu-Hui; Huang, Jen-How; Brandl, Helmut

    2017-03-01

    Reviewing the current state of knowledge about sequential extraction applied for soil vanadium (V) fractionation, we identified an urgent requirement of an sequential extraction (SE) specified for V. Namely, almost all previous SE extracted only 8.4%-48% of total V in soils (excluding residue). Thus, we proposed an eight-step SE for V fractionation in soils according to the knowledge gained from literature and our own dissolution experiments with model minerals. After extracting the mobilisable and adsorbed V with de-ionised water and 5mmol/L phosphate, 1mol/L pyrophosphate was applied to gather organic matter bound V which minimised the artefact dissolving Al and Fe (hydr)oxides occurred when using HNO 3 -H 2 O 2 for extraction. Extraction with 0.4mol/L NH 2 OH⋅HCl was highly selective toward manganese oxides. Fractionation of different crystalline Al and Fe (hydr)oxides associated V with 1mol/L HCl, 0.2mol/L oxalate buffer and 4mol/L HCl at 95°C especially improved the extractability of V incorporated with crystalline phase associated V. The suitability of our new SE scheme was confirmed by its higher selectivity against the target phases and higher extraction efficiencies (55%-77% of total V) with model minerals and 6 soils of different properties than previous SE. Copyright © 2016. Published by Elsevier B.V.

  9. Tunable Oxygen Functional Groups as Electrocatalysts on Graphite Felt Surfaces for All-Vanadium Flow Batteries.

    Science.gov (United States)

    Estevez, Luis; Reed, David; Nie, Zimin; Schwarz, Ashleigh M; Nandasiri, Manjula I; Kizewski, James P; Wang, Wei; Thomsen, Edwin; Liu, Jun; Zhang, Ji-Guang; Sprenkle, Vincent; Li, Bin

    2016-06-22

    A dual oxidative approach using O2 plasma followed by treatment with H2 O2 to impart oxygen functional groups onto the surface of a graphite felt electrode. When used as electrodes for an all-vanadium redox flow battery (VRB) system, the energy efficiency of the cell is enhanced by 8.2 % at a current density of 150 mA cm(-2) compared with one oxidized by thermal treatment in air. More importantly, by varying the oxidative techniques, the amount and type of oxygen groups was tailored and their effects were elucidated. It was found that O-C=O groups improve the cells performance whereas the C-O and C=O groups degrade it. The reason for the increased performance was found to be a reduction in the cell overpotential after functionalization of the graphite felt electrode. This work reveals a route for functionalizing carbon electrodes to improve the performance of VRB cells. This approach can lower the cost of VRB cells and pave the way for more commercially viable stationary energy storage systems that can be used for intermittent renewable energy storage. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Vanadium accelerates horizontal transfer of tet(M) gene from marine Photobacterium to Escherichia coli.

    Science.gov (United States)

    Suzuki, Satoru; Kimura, Midori; Agusa, Tetsuro; Rahman, Habibur M

    2012-11-01

    Vanadium is a contaminant from steel additive and ship fuel in coastal and port areas, and its effect on marine microbes remains largely unknown. We showed that vanadium accelerates transfer of the tetracycline resistance gene tet(M) from Photobacterium to Escherichia coli, and found a positive correlation between the concentration of vanadium in natural marine sediment and the rate of oxytetracycline resistance. These results suggest the possibility that vanadium may play a role in the preservation and horizontal transfer of antibiotic resistance genes in the marine environment. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  11. Distribution of vanadium and vanadylporphyrines in petroleum fractions of different chemical types

    Energy Technology Data Exchange (ETDEWEB)

    Aleshin, G.N.; Altukhova, Z.P.; Antipenko, V.R.; Marchenko, S.P.; Kam' yanov, V.F.

    Distribution of vanadium among petroleum components: tars, asphaltenes and oils from various levels of Samotlorsk fields was studied. It was shown that the predominant fraction of vanadium and vanadyl porphyrines is concentrated in petroleum tars. The highest absolute concentration of V was noted in the asphaltene fraction; however, vanadium atoms were found to be bound to heteroatomic fragments of the tarry-asphaltene compounds. Up to 98% of vanadium contained in asphaltenes and almost all V atoms in oil fractions are bound by non-porphyrinyl compounds. With increased methanization of the petroleum fractions, their V content drops rapidly. 5 references, 2 figures.

  12. One-Dimensional Vanadium Dioxide Nanostructures for Room Temperature Hydrogen Sensors

    Directory of Open Access Journals (Sweden)

    Aline Simo

    2015-06-01

    Full Text Available In relation to hydrogen (H2 economy in general and gas sensing in particular, an extensive set of one dimensional (1-D nano-scaled oxide materials are being investigated as ideal candidates for potential gas sensing applications. This is correlated to their set of singular surface characteristics, shape anisotropy and readiness for integrated devices. Nanostructures of well- established gas sensing materials such as Tin Oxide (SnO2, Zinc Oxide (ZnO, Indium (III Oxide (In2O3, and Tungsten Trioxide (WO3 have shown higher sensitivity and gas selectivity, quicker response, faster time recovery, as well as an enhanced capability to detect gases at low concentrations. While the overall sensing characteristics of these so called 1-D nanomaterials are superior, they are efficient at high temperature; generally above 200 0C. This operational impediment results in device complexities in integration that limit their technological applications, specifically in their miniaturized arrangements. Unfortunately, for room temperature applications, there is a necessity to dope the above mentioned nano-scaled oxides with noble metals such as Platinum (Pt, Palladium (Pd, Gold (Au, Ruthenium (Ru. This comes at a cost. This communication reports, for the first time, on the room temperature enhanced H2 sensing properties of a specific phase of pure Vanadium Dioxide (VO2 phase A in their nanobelt form. The relatively observed large H2 room temperature sensing in this Mott type specific oxide seems to reach values as low as 14 ppm H2 which makes it an ideal gas sensing in H2 fuelled systems.

  13. A novel process for comprehensive utilization of vanadium slag

    Science.gov (United States)

    Liu, Li-ying; Du, Tao; Tan, Wen-jun; Zhang, Xin-pu; Yang, Fan

    2016-02-01

    Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas, which cause serious environmental problems. In this study, a new process for the comprehensive utilization of vanadium slag was proposed, wherein zeolite A and a V2O5/TiO2 system were synthesized. The structural properties of the as-synthesized zeolite A and the V2O5/TiO2 system were characterized using various experimental techniques, including X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and infrared spectroscopy. The results reveal that zeolite A and the V2O5/TiO2 system are successfully obtained with high purity. The results of gas adsorption measurements indicate that the prepared zeolite A exhibits high selectivity for CO2 over N2 and is a candidate material for CO2 capture from flue-gas streams.

  14. Hypoglycemic activity of Grifola frondosa rich in vanadium.

    Science.gov (United States)

    Cui, Bo; Han, Linna; Qu, Jingran; Lv, Yingtao

    2009-11-01

    The hypoglycemic activity of fermented mushroom of Grifola frondosa rich in vanadium (GFRV) was studied in this paper. Alloxan- and adrenalin-induced hyperglycemic mice were used in the study. The blood glucose and the HbA1c of the mice were analyzed respectively. After the mice were administered (ig) with GFRV, the blood glucose and the HbA1c of alloxan-induced hyperglycemic mice decreased (p < 0.05, p < 0.01) and ascension of blood glucose induced by adrenalin was inhibited (p < 0.01). Also, the bodyweight of the alloxan-induced hyperglycemic mice was increased gradually. In the fermented mushroom of G. frondosa, vanadium at lower doses in combination with G. frondosa induced significant decreases of the blood glucose and HbA1c levels in hyperglycemic mice.

  15. Spectrophotometric determination of catecholamine using vanadium and eriochrome cyanine r

    Energy Technology Data Exchange (ETDEWEB)

    Nagaraja, Padmarajaiah; Shrestha, Ashwinee Kumar; Shivakumar, Anantharaman; Al-Tayar, Naef Ghallab Saeed; Gowda, Avinask K., E-mail: profpn58@yahoo.co [University of Mysore, Manasagangotri (India). Dept. of Studies in Chemistry

    2011-07-01

    highly sensitive spectrophotometric method for the analysis of catecholamine drugs; L-dopa and methyldopa, is described. The analysis is based on the reaction of drug molecules with vanadium (V) which is reduced to vanadium (IV) and form complex with eriochrome cyanine R to give products having maximum absorbance ({lambda}{sub max}) at 565 nm. Beer's law is obeyed in the range 0.028-0.84 and 0.099-0.996 {mu}g mL{sup -1} for L-dopa and methyldopa, respectively. The statistical analysis as well as comparison with reported methods demonstrated high precision and accuracy of the proposed method. The method was successfully applied in the analysis of pharmaceutical preparations. (author)

  16. Speciation of Chromium and Vanadium in Medicinal Plants ...

    African Journals Online (AJOL)

    In this study, Cr(VI) and V(V) were determined in medicinal plants collected from the farm located between two smelters. Chromium(VI) and vanadium(V) were leached from medicinal plants with 0.1 M Na2CO3 prior their determination by ETAAS. The concentration of Cr(VI) in medicinal plants varied between 3.1 ± 0.5 μg ...

  17. Acute toxicity of vanadium to two species of freshwater fish

    Energy Technology Data Exchange (ETDEWEB)

    Knudtson, B.K.

    1979-09-01

    Goldfish (Carassius auratus) and guppies (Lebistes reticulatus) were the two freshwater, thermophilous fishes chosen for use in this study. These species were selected for the following reasons: (1) low cost/individual, (2) ready availability, (3) ease of care and handling, (4) suspected differences between the two species in their responses to this metal, and (5) the usefulness of both as generalized models for the response of freshwater and marine fishes to vanadium.

  18. Spleen and bone marrow megakaryocytes as targets for inhaled vanadium

    OpenAIRE

    Teresa I Fortoul; Piñón-Zarate, Gabriela; Diaz-Bech, María Eugenia; González-Villalva, Adriana; Mussali-Galante, Patricia; Rodriguez-Lara,Vilaney; Colin-Barenque, Laura; Martinez Pedraza, Michelle; Luis F. Montaño

    2008-01-01

    An increased incidence in ischemic and thromboembolic events in the population of cities with rising air suspended particle pollution has suggested the interaction of some of the components of these particles in the coagulation system. A previous report from our laboratory identified thrombocytosis as a consequence of the subacute and chronic inhalation of vanadium. With this preceding information we decided to evaluate the effects of this element in the spleen and bon...

  19. Corrosion resistance investigation of vanadium alloys in liquid lithium

    Science.gov (United States)

    Borovitskaya, I. V.; Lyublinskiy, I. E.; Bondarenko, G. G.; Paramonova, V. V.; Korshunov, S. N.; Mansurova, A. N.; Lyakhovitskiy, M. M.; Zharkov, M. Yu.

    2016-12-01

    A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10-3 wt %) of vanadium and vanadium alloys (V-1.86Ga, V-3.4Ga-0.62Si, V-4.81Ti-4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 1022 m-2 at an irradiation temperature of 400°C. The degree of corrosion was estimated by measuring the changes in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.

  20. A combined theoretical-experimental study of interactions between vanadium ions and Nafion membrane in all-vanadium redox flow batteries

    Science.gov (United States)

    Intan, Nadia N.; Klyukin, Konstantin; Zimudzi, Tawanda J.; Hickner, Michael A.; Alexandrov, Vitaly

    2018-01-01

    Vanadium redox flow batteries (VRFBs) are a promising solution for large-scale energy storage, but a number of problems still impede the deployment of long-lifetime VRFBs. One important aspect of efficient operation of VRFBs is understanding interactions between vanadium species and the membrane. Herein, we investigate the interactions between all four vanadium cations and Nafion membrane by a combination of infrared (IR) spectroscopy and density-functional-theory (DFT)-based static and molecular dynamics simulations. It is observed that vanadium species primarily lead to changes in the IR spectrum of Nafion in the SO3- spectral region which is attributed to the interaction between vanadium species and the SO3- exchange sites. DFT calculations of vanadium -Nafion complexes in the gas phase show that it is thermodynamically favorable for all vanadium cations to bind to SO3- via a contact pair mechanism. Car-Parrinello molecular dynamics-based metadynamics simulations of cation-Nafion systems in aqueous solution suggest that V2+ and V3+ species coordinate spontaneously to SO3-, which is not the case for VO2+ and VO2+. The interaction behavior of the uncycled membrane determined in this study is used to explain the experimentally observed changes in the vibrational spectra, and is discussed in light of previous results on device-cycled membranes.

  1. Catalytic and kinetic spectrophotometric method for determination of vanadium(V by 2,3,4-trihydroxyacetophenonephenylhydrazone

    Directory of Open Access Journals (Sweden)

    P.V. Chalapathi

    2014-12-01

    Full Text Available A new catalytic and kinetic spectrophotometric method for the determination of vanadium(V was studied using 2,3,4-trihydroxyacetophenonephenylhydrazone (THAPPH as an analytical reagent. The present method was developed on the catalytic effect of vanadium on oxidation of THAPPH by hydrogen peroxide in hydrochloric acid–potassium chloride buffer (pH = 2.8 at the 20th minute. The metal ion has formed 1:2 (M:L complex with THAPPH. Beer’s law was obeyed in the range 20–120 ng/mL of V(V at λmax 390 nm. The sensitivity of the method was calculated in terms of molar absorptivity (1.999 × 105 L mol−1cm−1 and Sandell’s sensitivity (0.000254 μg cm−2, shows that this method is more sensitive. The standard deviation (0.0022, relative standard deviation (0.56%, confidence limit (±0.0015 and standard error (0.0007 revealed that the developed method has more precision and accuracy. The stability constant was calculated with the help of Asmu’s (9.411 × 10−11 and Edmond’s & Birnbaum’s (9.504 × 10−11 methods at room temperature. The interfering effect of various cations and anions was also studied. The present method was successfully applied for the determination of vanadium(V in environmental and alloy samples. The method’s validity was checked by comparing the results obtained with atomic-absorption spectrophotometry and also by evaluation of results using F-test.

  2. The toxicity of vanadium on gastrointestinal, urinary and reproductive system, and its influence on fertility and fetuses malformations

    Directory of Open Access Journals (Sweden)

    Aleksandra Wilk

    2017-09-01

    Additionally, this research identifies the doses of vanadium which lead to pathological alterations becoming visible within tissues. Moreover, this study includes information about the protective efficacy of some substances in view of the toxicity of vanadium.

  3. Preparation and Localization of a Monoclonal Antibody against a Vanadium-Associated Protein Extracted from the Blood Cells of the Vanadium-Rich Ascidian, Ascidia sydneiensis samea

    OpenAIRE

    Junko, Wuchiyama; Yasuhiro, Nose; Taro, Uyama; Hitoshi, Michibata; Mukaishima Marine Biological Laboratory, Faculty of Science and Laboratory of Marine Molecular Biology, Graduate School of Science, Hiroshima University

    1997-01-01

    Ascidians are known to accumulate high levels of vanadium in their blood cells, Recently, we found a vanadium-associated protein (VAP) in blood cells of a vanadium-rich ascidian, Ascidia sydneiensis samea. In this paper, we raised a monoclonal antibody against VAP, designated F8DH. Immunoblot analysis showed that F8DH recognized 2 related peptides of 15 kDa and 16 kDa of VAP. Using F8DH, VAP was shown to be in the cytoplasm of vanadocytes and compartment cells, both of which were reported to ...

  4. Amphoteric Ion-Exchange Membranes with Significantly Improved Vanadium Barrier Properties for All-Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Nibel, Olga; Rojek, Tomasz; Schmidt, Thomas J; Gubler, Lorenz

    2017-07-10

    All-vanadium redox flow batteries (VRBs) have attracted considerable interest as promising energy-storage devices that can allow the efficient utilization of renewable energy sources. The membrane, which separates the porous electrodes in a redox flow cell, is one of the key components in VRBs. High rates of crossover of vanadium ions and water through the membrane impair the efficiency and capacity of a VRB. Thus, membranes with low permeation rate of vanadium species and water are required, also characterized by low resistance and stability in the VRB environment. Here, we present a new design concept for amphoteric ion-exchange membranes, based on radiation-induced grafting of vinylpyridine into an ethylene tetrafluoroethylene base film and a two-step functionalization to introduce cationic and anionic exchange sites, respectively. During long-term cycling, redox flow cells containing these membranes showed higher efficiency, less pronounced electrolyte imbalance, and significantly reduced capacity decay compared to the cells with the benchmark material Nafion 117. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Recovery of Vanadium from H2SO4-HF Acidic Leaching Solution of Black Shale by Solvent Extraction and Precipitation

    OpenAIRE

    Xingbin Li; Chang Wei; Zhigan Deng; Cunxiong Li; Gang Fan; Minting Li; Hui Huang

    2016-01-01

    The recovery of vanadium from sulfuric and hydrofluoric mixed acid solutions generated by the direct leaching of black shale was investigated using solvent extraction and precipitation methods. The process consisted of reduction, solvent extraction, and stripping, followed by precipitation and calcination to yield vanadium pentoxide. The influence of various operating parameters on the extraction and recovery of vanadium was studied. Vanadium (IV) was selectively extracted using a mixture of ...

  6. The toxicity of vanadium on gastrointestinal, urinary and reproductive system, and its influence on fertility and fetuses malformations

    OpenAIRE

    Aleksandra Wilk; Dagmara Szypulska-Koziarska; Barbara Wiszniewska

    2017-01-01

    Vanadium is a transition metal that has a unique and beneficial effect on both humans and animals. For many years, studies have suggested that vanadium is an essential trace element. Its biological properties are of interest due to its therapeutic potential, including in the treatment of diabetes mellitus. Vanadium deficiencies can lead to a range of pathologies. However, excessive concentration of this metal can cause irreversible damage to various tissues and organs. Vanadium toxicity mainl...

  7. The rice field cyanobacteria Anabaena azotica and Anabaena sp. CH1 express vanadium-dependent nitrogenase

    NARCIS (Netherlands)

    Boison, G.; Steingen, C.; Stal, L.J.; Bothe, H.

    2006-01-01

    Anabaena azotica FACHB-118 and Anabaena sp. CH1, heterocystous cyanobacteria isolated from Chinese and Taiwanese rice fields, expressed vanadium-containing nitrogenase when under molybdenum deficiency. This is the second direct observation of an alternative nitrogenase in cyanobacteria. The vanadium

  8. Bioaccumulation of vanadium and other trace metals in livers of Alaskan cetaceans and pinnipeds.

    Science.gov (United States)

    Mackey, E A; Becker, P R; Demiralp, R; Greenberg, R R; Koster, B J; Wise, S A

    1996-05-01

    Concentrations for 38 elements are routinely measured in the marine mammal liver tissues archived in the National Biomonitoring Specimen Bank (NBSB). Results show that hepatic concentrations of vanadium, selenium, silver, cadmium, and mercury are positively correlated with age for beluga whales (Delphinapterus leucas) and of vanadium, selenium, cadmium, and mercury with length for ringed seals (Phoca hispada). Many researchers have reported linear correlations of hepatic selenium, cadmium, and mercury with marine mammal age; however, there is only one other report of a linear correlation of hepatic vanadium with marine mammal age. Vanadium levels are at or below detection limits (marine mammals from the NBSB but are present at levels ranging from 0.02 to 1.2 micrograms/g of wet weight in the tissues of Alaskan marine mammals. Although only three bearded seal (Eriganthus barbatus) and three bow-head whale (Balaena mysticetus) liver samples have been analyzed, hepatic vanadium levels also increased with animal size for these species. The presence of relatively high levels of vanadium in the livers of these Alaskan animals may reflect a unique dietary source of vanadium, a unique geochemical source of vanadium, or anthropogenic input to the Alaskan marine environment.

  9. Vanadium Mining and Cattle Health : Sentinel studies, epidemiological and veterinary public health issues

    NARCIS (Netherlands)

    Gummow, B.

    2005-01-01

    The thesis covers a field outbreak investigation into the cause and pathogenesis of "illthrift" on a dairy farm that was due to vanadium exposure, it examines methods of treating vanadium poisoning in cattle using an experimental study, looks at the use of cattle as sentinels for detecting and

  10. Anthropogenic vanadium emissions to air and ambient air concentrations in North-West Europe

    NARCIS (Netherlands)

    Visschedijk, A.H.J.; Denier van der Gon, H.A.C.; Hulskotte, J.H.J.; Quass, U.

    2013-01-01

    An inventory of Vanadium emissions for North-West Europe for the year 2005 was made based on an identification of the major sources. The inventory covers Belgium, Germany, Denmark, France, United Kingdom, Luxembourg, Netherlands and the OSPAR region of the North Sea. Vanadium emission were

  11. Synthesis of nanoparticles of vanadium carbide in the ferrite of nodular cast iron

    CERN Document Server

    Fras, E; Guzik, E; Lopez, H

    2005-01-01

    The synthesis method of nanoparticles of vanadium carbide in nodular cast iron is presented. After introduction of this method, the nanoparticles with 10-70 nm of diameter was obtained in the ferrite. The diffraction investigations confirmed that these particles are vanadium carbides of type V/sub 3/C/sub 4/.

  12. The public health implications of farming cattle in areas with high background concentrations of vanadium

    NARCIS (Netherlands)

    Gummow, B.; Botha, C.J.; Noordhuizen, J.P.T.M.; Heesterbeek, J.A.P.

    2005-01-01

    Forty-two adult Brahman-cross cattle farmed extensively in two groups, immediately adjacent to and 2 km from a vanadium processing plant respectively, were slaughtered over a 5 year period at a nearby abattoir. Cattle were being exposed to vanadium at close to no-adverse-effect levels. The dose of

  13. Diel cycles in dissolved barium, lead, iron, vanadium, and nitrite in a stream draining a former zinc smelter site near Hegeler, Illinois

    Science.gov (United States)

    Kay, R.T.; Groschen, G.E.; Cygan, G.; Dupre, David H.

    2011-01-01

    Diel variations in the concentrations of a number of constituents have the potential to substantially affect the appropriate sampling regimen in acidic streams. Samples taken once during the course of the day cannot adequately reflect diel variations in water quality and may result in an inaccurate understanding of biogeochemical processes, ecological conditions, and of the threat posed by the water to human health and the associated wildlife. Surface water and groundwater affected by acid drainage were sampled every 60 to 90. min over a 48-hour period at a former zinc smelter known as the Hegeler Zinc Superfund Site, near Hegeler, Illinois. Diel variations related to water quality in the aquifer were not observed in groundwater. Diel variations were observed in the temperature, pH, and concentration of dissolved oxygen, nitrite, barium, iron, lead, vanadium, and possibly uranium in surface water. Temperature, dissolved oxygen, nitrite, barium, lead, and uranium generally attained maximum values during the afternoon and minimum values during the night. Iron, vanadium, and pH generally attained minimum values during the afternoon and maximum values during the night. Concentrations of dissolved oxygen were affected by the intensity of photosynthetic activity and respiration, which are dependent upon insolation. Nitrite, an intermediary in many nitrogen reactions, may have been formed by the oxidation of ammonium by dissolved oxygen and converted to other nitrogen species as part of the decomposition of organic matter. The timing of the pH cycles was distinctly different from the cycles found in Midwestern alkaline streams and likely was the result of the photoreduction of Fe3+ to Fe 2+ and variations in the intensity of precipitation of hydrous ferric oxide minerals. Diel cycles of iron and vanadium also were primarily the result of variations in the intensity of precipitation of hydrous ferric oxide minerals. The diel variation in the concentrations of lead, uranium

  14. CaO insulator coatings on a vanadium-base alloy in liquid 2 at.% calcium-lithium

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, IL (United States)

    1996-10-01

    The electrical resistance of CaO coatings produced on V-4%Cr-4%Ti and V-15%Cr-5%Ti by exposure of the alloy (round bottom samples 6-in. long by 0.25-in. dia.) to liquid lithium that contained 2 at.% dissolved calcium was measured as a function of time at temperatures between 300-464{degrees}C. The solute element, calcium in liquid lithium, reacted with the alloy substrate at these temperatures for 17 h to produce a calcium coating {approx}7-8 {mu}m thick. The calcium-coated vanadium alloy was oxidized to form a CaO coating. Resistance of the coating layer on V-15Cr-5Ti, measured in-situ in liquid lithium that contained 2 at.% calcium, was 1.0 x 10{sup 10} {Omega}-cm{sup 2} at 300{degrees}C and 400 h, and 0.9 x 10{sup 10} {Omega}-cm{sup 2} at 464{degrees}C and 300 h. Thermal cycling between 300 and 464{degrees}C changed the resistance of the coating layer, which followed insulator behavior. Examination of the specimen after cooling to room temperature revealed no cracks in the CaO coating. The coatings were evaluated by optical microscopy, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray analysis. Adhesion between CaO and vanadium alloys was enhanced as exposure time increased.

  15. The Influence of Vanadium on Ferrite and Bainite Formation in a Medium Carbon Steel

    Science.gov (United States)

    Sourmail, T.; Garcia-Mateo, C.; Caballero, F. G.; Cazottes, S.; Epicier, T.; Danoix, F.; Milbourn, D.

    2017-09-01

    The influence of vanadium additions on transformation kinetics has been investigated in a medium carbon forging steel. Using dilatometry to track transformation during continuous cooling or isothermal transformation, the impact of vanadium on both ferrite-pearlite and bainite has been quantified. Transmission electron microscopy and atom probe tomography have been used to establish whether vanadium was present in solid solution, or as clusters and precipitates. The results show that vanadium in solid solution has a pronounced retarding influence on ferrite-pearlite formation and that, unlike in the case of niobium, this effect can be exploited even during relatively slow cooling. The influence on bainite transformation was found to depend on temperature; an explanation in terms of the effect of vanadium on heterogeneous nucleation is tentatively proposed.

  16. Effect of vanadium contamination on the framework and micropore structure of ultra stable Y-zeolite.

    Science.gov (United States)

    Etim, U J; Xu, B; Ullah, Rooh; Yan, Z

    2016-02-01

    Y-zeolites are the main component of fluid catalytic cracking (FCC) catalyst for conversion of crude petroleum to products of high demand including transportation fuel. We investigated effects of vanadium which is present as one of the impurities in FCC feedstock on the framework and micropore structure of ultra-stable (US) Y-zeolite. The zeolite samples were prepared and characterized using standard techniques including: (1) X-ray diffraction, (2) N2 adsorption employing non local density functional theory method, NLDFT, (3) Transmittance and Pyridine FTIR, (4) Transmittance electron microscopy (TEM), and (5) (27)Al and (29)Si MAS-NMR. Results revealed that in the presence of steam, vanadium caused excessive evolution of non inter-crystalline mesopores and structural damage. The evolved mesopore size averaged about 25.0nm at 0.5wt.% vanadium loading, far larger than mesopore size in zeolitic materials with improved hydrothermal stability and performance for FCC catalyst. A mechanism of mesopore formation based on accelerated dealumination has been proposed and discussed. Vanadium immobilization experiments conducted to mitigate vanadium migration into the framework clearly showed vanadium is mobile at reaction conditions. From the results, interaction of vanadium with the passivator limits and decreases mobility and activity of vanadium into inner cavities of the zeolite capable of causing huge structure breakdown and acid sites destruction. This study therefore deepens insight into the causes of alteration in activity and selectivity of vanadium contaminated catalyst and hints on a possible mechanism of passivation in vanadium passivated FCC catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Studies of reactor irradiation effect on hydrogen isotope release from vanadium alloy V4Cr4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Kulsartov, T. [Kazakhstan State University, Tole-bi-str. 96a., Almaty (Kazakhstan); Shestakov, V. [Kazakhstan State University, Tole-bi-str. 96a., Almaty (Kazakhstan); Chikhray, Y. [Kazakhstan State University, Tole-bi-str. 96a., Almaty (Kazakhstan); Kenzhin, Y. [Institute of Atomic Energy NNC RK, Krasnoarmeyskaya-str. 10, Kurchatov (Kazakhstan); Kolbayenkov, A. [Institute of Atomic Energy NNC RK, Krasnoarmeyskaya-str. 10, Kurchatov (Kazakhstan); Tazhibayeva, I. [National Nuclear Center, Lenin-str. 6, Kurchatov (Kazakhstan)

    2007-08-01

    Vanadium alloys are most promising materials being considered for lithium blanket-breeder in future fusion reactors. The primary reason for these stems from good combination of physical-mechanical and radiation properties of vanadium alloys. In operational conditions of fusion reactors the very important issue is behavior of vanadium alloy with respect to hydrogen isotopes under neutron and gamma irradiation. This paper shows results of the experimental studies of reactor irradiation influence on parameters of hydrogen release from vanadium alloys. Experiments were carried out for various levels of reactor irradiation and showed the effect of irradiation on parameters of hydrogen release from vanadium alloy V4Cr4Ti.

  18. Corrosion resistance investigation of vanadium alloys in liquid lithium

    Energy Technology Data Exchange (ETDEWEB)

    Borovitskaya, I. V., E-mail: symp@imet.ac.ru [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Lyublinskiy, I. E. [JSC Red Star (Russian Federation); Bondarenko, G. G. [National Research University Higher School of Economics (Russian Federation); Paramonova, V. V. [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Korshunov, S. N.; Mansurova, A. N. [National Research Center Kurchatov Institute (Russian Federation); Lyakhovitskiy, M. M. [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Zharkov, M. Yu. [JSC Red Star (Russian Federation)

    2016-12-15

    A major concern in using vanadium alloys for first wall/blanket systems in fusion reactors is their activity with regard to nonmetallic impurities in the coolants. This paper presents the results of studying the corrosion resistance in high-purity liquid lithium (with the nitrogen and carbon content of less than 10{sup –3} wt %) of vanadium and vanadium alloys (V–1.86Ga, V–3.4Ga–0.62Si, V–4.81Ti–4.82Cr) both in the initial state and preliminarily irradiated with Ar+ ions with energy of 20 keV to a dose of 10{sup 22} m{sup –2} at an irradiation temperature of ~400°C. The degree of corrosion was estimated by measuring the changes in the weight and microhardness. Corrosion tests were carried out under static isothermal conditions at a temperature of 600°C for 400 h. The identity of corrosion mechanisms of materials both irradiated with Ar ions and not irradiated, which consisted in an insignificant penetration of nitrogen into the materials and a substantial escape of oxygen from the materials, causing the formation of a zone with a reduced microhardness near the surface, was established. The influence of the corrosive action of lithium on the surface morphology of the materials under study was found, resulting in the manifestation of grain boundaries and slip lines on the sample surface, the latter being most clearly observed in the case of preliminary irradiation with Ar ions.

  19. Lattice-Symmetry-Driven Phase Competition in Vanadium Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Tselev, Alexander [ORNL; Luk' yanchuk, Prof. Igor A. [University of Picardie Jules Verne, Amiens, France; Ivanov, Ilia N [ORNL; Budai, John D [ORNL; Tischler, Jonathan Zachary [ORNL; Strelcov, Evgheni [Southern Illinois University; Kolmakov, Andrei [Southern Illinois University; Kalinin, Sergei V [ORNL

    2011-01-01

    We performed group-theoretical analysis of the symmetry relationships between lattice structures of R, M1, M2, and T phases of vanadium dioxide in the frameworks of the general Ginzburg-Landau phase transition theory. The analysis leads to a conclusion that the competition between the lower-symmetry phases M1, M2, and T in the metal-insulator transition is pure symmetry driven, since all the three phases correspond to different directions of the same multi-component structural order parameter. Therefore, the lower-symmetry phases can be stabilized in respect to each other by small perturbations such as doping or stress.

  20. Iron(II)- or vanadium(IV)-containing siliceous gels

    OpenAIRE

    Hutter, Frank; Schmidt, Helmut K.; Scholze, Horst

    1986-01-01

    Iron(II)-containing SiO2 gels can be prepared by the hydrolysis and condensation of tetramethoxysilane in methanolic solutions of iron(II) chloride. These gels show an absorption at 1000 nm indicating the presence of iron(II). In opposition to that, iron(II) cannot be introduced into organically modified gels of the 3-glycidyloxypropyltrimethoxysilane type. Vanadium(IV) can be incorporated into both gels. Unlike the SiO2 gels, the organically modified gels are compact and elastic. The spectra...

  1. Medium carbon vanadium micro alloyed steels for drop forging

    Energy Technology Data Exchange (ETDEWEB)

    Jeszensky, Gabor; Plaut, Ronald Lesley

    1992-12-31

    Growing competitiveness of alternative manufacturing routes requires cost minimization in the production of drop forged components. The authors analyse the potential of medium carbon, vanadium microalloyed steels for drop forging. Laboratory and industrial experiments have been carried out emphasizing deformation and temperature cycles, strain rates and dwell times showing a typical processing path, associated mechanical properties and corresponding microstructures. The steels the required levels of mechanical properties on cooling after forging, eliminating subsequent heat treatment. The machinability of V-microalloyed steels is also improved when compared with plain medium carbon steels. (author) 17 refs., 19 figs., 5 tabs.

  2. Growth of Vanadium Carbide by Halide-Activated Pack Diffusion

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Dahl, Kristian Vinter

    The present work investigates growth of vanadium carbide (VC) layers by the pack diffusion method on a Vanadis 6 tool steel. The VC layers were produced by pack diffusion at 1000°C for 1, 4 and 16 hours. The VC layers were characterized with optical and electron microscopy, Vickers hardness tests...... and X-ray diffraction. Homogeneous VC mono-phase layers with Vickers hardness of more than 2400 HV were obtained. Hardening and tempering of the vanadized Vanadis 6 steel did not affect the VC layers....

  3. X-ray-induced persistent photoconductivity in vanadium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Dietze, S. H.; Marsh, M. J.; Wang, Siming; Ramírez, J. -G.; Cai, Z. -H.; Mohanty, J. R.; Schuller, Ivan K.; Shpyrko, O. G.

    2014-10-08

    The resistivity of vanadium dioxide (VO2) decreased by over one order of magnitude upon localized illumination with x rays at room temperature. Despite this reduction, the structure remained in the monoclinic phase and had no signature of the high-temperature tetragonal phase that is usually associated with the lower resistance. Once illumination ceased, relaxation to the insulating state took tens of hours near room temperature. However, a full recovery of the insulating state was achieved within minutes by thermal cycling. We show that this behavior is consistent with random local-potential fluctuations and random distribution of discrete recombination sites used to model residual photoconductivity.

  4. Atomistic modeling of the anomalous helium behaviors in vanadium

    OpenAIRE

    Hu, Nengwen; Wang, Canglong; Deng, Huiqiu; Xiao, Shifang; Wang, Chengbin; Yang, Lei; Hu, Wangyu

    2016-01-01

    Ab initio calculations have been performed to clarify the primary behaviors of He atoms in vanadium and to generate the database for the development of the interatomic potential for V-He system within the framework of the"s-band"model.The calculated formation energies of the tetrahedral,octahedral and substitutional He defects,as well as those for He2,He3 and He2V clusters are reasonable when compared with relevant experimental results and ab initio calculations under the same conditions.The ...

  5. Pentavalent vanadium at concentration of the underground water level enhances the sweet taste sense to glucose in college students.

    Science.gov (United States)

    Nagai, Masanori; Saitoh, Junko; Ohno, Hiromi; Hitomi, Chiaki; Wada, Maki

    2006-02-01

    Underground water in volcanic areas contains vanadium when the basalt layer exists among igneous rocks. The concentration of vanadium in drinking water sometimes exceeds 0.8 microM in these areas, however, the physiological effects of vanadium, especially non-toxic effects, at concentrations lower than 1 microM are unknown. In the present experiments, we examined the effect of pentavalent vanadium and tetravalent vanadium at 0.8 and 8.0 microM concentrations on the recognition threshold to taste substances in healthy college students. Pentavalent vanadium, ammonium vanadate, lowered the sweet taste threshold to glucose at 0.8 and 8.0 microM as well. Tetravalent vanadium, vanadium sulfate, did not alter the threshold to glucose either at 8.0 microM or at 0.8 microM. Ammonium vanadate also decreased the sweet taste threshold to L-proline at 8.0 microM. Ammonium vanadate did not influence the sour taste threshold to hydrogen chloride. Neither ammonium sulfate nor ammonium bicarbonate altered the sweet taste threshold to glucose. Therefore, the effect of ammonium vanadate on the sweet taste threshold is attained by vanadium but not by ammonium. It was concluded that pentavalent vanadium at 0.8 microM intensifies the sweet taste sense to glucose rather specifically. We have first shown the physiological effect of vanadium at the concentration of the underground water level.

  6. Effects of vanadium on population growth and Na-K-ATPase activity of the brackish water hydroid Cordylophora caspia

    Energy Technology Data Exchange (ETDEWEB)

    Ringelband, U.; Karbe, L. [Institut fuer Hydrobiologie und Fischereiwissenschaft, Hamburg (Germany)

    1996-07-01

    Vanadium, a relatively abundant heavy metal, enters the environment naturally through rock weathering. A large fraction of vanadium input is of human origin. The combustion of petroleum- and coal-products, which contain relatively high concentrations of vanadium, is one of the most important sources of the enrichment of vanadium in the environment. As it is used as an alloy, and vanadium rich iron-ores of various origin are used in steel production, the residual slag-stones of the steel industry can contain considerable vanadium concentrations. Wherever slag-stones serve as a cheap and convenient material in riverbank reinforcement, vanadium can leach into the aquatic environment. Vanadium is regarded as an essential trace element for higher animals. Cantley et al. indicated a regulatory function of vanadate in vivo. Although considerable information is available on the toxic effects of vanadium on humans, very little is known about the toxicity of vanadium towards aquatic organisms, especially invertebrates. Bell and Sargent have shown an inhibition of Na-K-ATPase activity in gills of the eel Anguilla anguilla. Holleland and Towle have demonstrated the inhibition of Na-K-ATPase activity in the gills of the shore crab Carcinus maenas. The aim of this study was to determine the toxicity of vanadium towards the brackish water hydroid Cordylophora caspia. Hydroids are known to be particularly sensitive to heavy metals and their asexual reproduction can be used in a well-established population growth test. Furthermore, the effects of vanadium on Na-K-ATPase activity in hydroids were studied in in vivo experiments, wherein the animals were exposed to sublethal concentrations of vanadium. In addition, the inhibition of Na-K-ATPase was measured in vitro, by adding vanadium to a microsomal preparation. 16 refs., 4 figs.

  7. Polypyrrole-vanadium oxide nanocomposite: polymer dominates crystallanity and oxide dominates conductivity

    Science.gov (United States)

    Roy, Swarup; Mishra, Suryakant; Yogi, Priyanka; Saxena, Shailendra K.; Mishra, Vikash; Sagdeo, Pankaj R.; Kumar, Rajesh

    2018-01-01

    A hybrid nanocomposite of polypyrrole (Ppy)-V2O5 has been fabricated and characterized for better understanding of material enabling one to use this for appropriate application as the nanocomposite shows better thermal stability. The characterization has been done using XRD, FT-IR, FESEM, and UV-Vis for their structure, surface morphology, respectively, along with TGA and two-probe method used for checking thermal stability, and DC electrical conductance and dielectric behavior of the electrical phenomena of sample. The analysis of XRD demonstrates that crystallinity of nanocomposites is the same as that of the polymer, even though interaction between conducting Ppy and V2O5 is present as evident from FT-IR spectroscopy. A variation in bandgap, in comparison with Ppy, is observed when V2O5 is added into it. The microstructural study of nanocomposites shows encapsulation of V2O5 particles in Ppy matrix with changes in morphology with increase in doping. Conductance results show that electrical conductivity of Ppy decayed on adding V2O5. It has also been found that addition of V2O5 in Ppy has noticeable effect on the dielectric properties.

  8. Fiber optic gas sensors with vanadium oxide and tungsten oxide nanoparticle coated claddings

    Science.gov (United States)

    Renganathan, B.; Sastikumar, D.; Raj, S. Gokul; Ganesan, A. R.

    2014-03-01

    Fiber optic gas sensors with nanoparticles of V2O5 and WO3 as the cladding of a PMMA fiber have been proposed in this work. The spectral response of these sensors for detection of ammonia, methanol and ethanol under various concentrations has been studied at room temperature. The time response characteristics of the sensors are also presented.

  9. Modification of halogen specificity of a vanadium-dependent bromoperoxidase.

    Science.gov (United States)

    Ohshiro, Takashi; Littlechild, Jennifer; Garcia-Rodriguez, Esther; Isupov, Michail N; Iida, Yasuaki; Kobayashi, Takushi; Izumi, Yoshikazu

    2004-06-01

    The halide specificity of vanadium-dependent bromoperoxidase (BPO) from the marine algae, Corallina pilulifera, has been changed by a single amino acid substitution. The residue R397 has been substituted by the other 19 amino acids. The mutant enzymes R397W and R397F showed significant chloroperoxidase (CPO) activity as well as BPO activity. These mutant enzymes were purified and their properties were investigated. The maximal velocities of CPO activities of the R397W and R397F enzymes were 31.2 and 39.2 units/mg, and the K(m) values for Cl(-) were 780 mM and 670 mM, respectively. Unlike the native enzyme, both mutant enzymes were inhibited by NaN(3). In the case of the R397W enzyme, the incorporation rate of vanadate into the active site was low, compared with the R397F and the wild-type enzyme. These results supported the existence of a specific halogen binding site within the catalytic cleft of vanadium haloperoxidases.

  10. Mechanical and electrochemical characterization of vanadium nitride (VN) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.C., E-mail: Jcesarca@calima.univalle.edu.co [Grupo de Peliculas Delgadas, Departamento de Fisica, Universidad del Valle, Cali (Colombia); Zambrano, G. [Grupo de Peliculas Delgadas, Departamento de Fisica, Universidad del Valle, Cali (Colombia); Aperador, W. [Ingenieria Mecatronica, Universidad Militar Nueva Granada, Bogota (Colombia); Escobar-Alarcon, L.; Camps, E. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico, DF 11801 (Mexico)

    2011-10-15

    Vanadium nitride (V-N) thin films were grown using a reactive d.c. magnetron sputtering process, from a vanadium target (99.999%) in an Ar/N{sub 2} gas mixture at different deposition bias voltage. Films were deposited onto silicon (1 0 0) and RUS-3 steel substrates at 400 deg. C. Structural, compositional, mechanical and electrochemical characterizations were performed by X-ray diffraction (XRD), elastic forward analysis (EFA), nanoindentation, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves, respectively. X-ray diffraction patterns show the presence of (1 1 1) and (2 0 0) crystallographic orientations associated to the V-N cubic phase. Nanoindentation measurements revealed that when the bias voltage increases from 0 V to -150 V the hardness and elastic modulus are increased from 11 GPa to 20 GPa and from 187 GPa to 221 GPa, respectively. EIS and Tafel curves showed that the corrosion rate of steel, coated with V-N single layer films deposited without bias voltage, diminishes 90% compared to the steel without this coating. On the other hand, when the V-N coating was deposited at the highest d.c. bias voltage (-150 V), the corrosion rate was greater than in the steel coated with zero-voltage (0 V) V-N films. This last result could be attributed to the formation of porosities produced by the ion bombardment during the deposition process.

  11. Mechanical and electrochemical characterization of vanadium nitride (VN) thin films

    Science.gov (United States)

    Caicedo, J. C.; Zambrano, G.; Aperador, W.; Escobar-Alarcon, L.; Camps, E.

    2011-10-01

    Vanadium nitride (V-N) thin films were grown using a reactive d.c. magnetron sputtering process, from a vanadium target (99.999%) in an Ar/N 2 gas mixture at different deposition bias voltage. Films were deposited onto silicon (1 0 0) and RUS-3 steel substrates at 400 °C. Structural, compositional, mechanical and electrochemical characterizations were performed by X-ray diffraction (XRD), elastic forward analysis (EFA), nanoindentation, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves, respectively. X-ray diffraction patterns show the presence of (1 1 1) and (2 0 0) crystallographic orientations associated to the V-N cubic phase. Nanoindentation measurements revealed that when the bias voltage increases from 0 V to -150 V the hardness and elastic modulus are increased from 11 GPa to 20 GPa and from 187 GPa to 221 GPa, respectively. EIS and Tafel curves showed that the corrosion rate of steel, coated with V-N single layer films deposited without bias voltage, diminishes 90% compared to the steel without this coating. On the other hand, when the V-N coating was deposited at the highest d.c. bias voltage (-150 V), the corrosion rate was greater than in the steel coated with zero-voltage (0 V) V-N films. This last result could be attributed to the formation of porosities produced by the ion bombardment during the deposition process.

  12. Kinetic spectrophotometric determination of trace amounts of selenium and vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Safavi, A.; Sedghy, H.R.; Shams, E. [Dept. of Chemistry, Shiraz Univ. (Iran)

    1999-11-01

    A sensitive kinetic spectrophotometric method has been developed for the determination of Se(IV) over the range of 45 to 4000 ng in 10 mL of solution. The method is based on the catalytic effect of Se(IV) on the reduction reaction of bromate by hydrazinium dichloride, with subsequent reaction of Ponceau S with products of the above reaction (chlorine and bromine), causing color changing of Ponceau S. Method development includes optimization of time interval for measurement of slope, pH, reagents concentration, and temperature. The optimized conditions yielded a theoretical detection limit of 33 ng/10 mL of solution of Se(IV). The interfering effects were studied and removed. The method was applied to the determination of selenium in spiked water, Kjeldahl tablet, selenium tablet, and shampoo. Vanadium(V) has an inhibition effect on the catalyzed reaction of bromate and hydrazine by selenium. Using this effect, V(V) can be determined in the range of 70 to 2500 ng in 10 mL of solution. The optimization procedure includes pH and selenium concentration. An extraction method was used for interference removal. The method was applied to the determination of vanadium in petroleum. (orig.)

  13. Synthesis and electrochemical performance of bismuth-vanadium oxyfluoride

    Energy Technology Data Exchange (ETDEWEB)

    Liu Li [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, School of Chemistry, Xiangtan University, Hunan, Xiangtan 411105 (China); Wang Xianyou, E-mail: wxianyou@yahoo.com [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, School of Chemistry, Xiangtan University, Hunan, Xiangtan 411105 (China); Wang Xingyan; Wang Xin; Tian Fanghua; Yi Lanhua [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, School of Chemistry, Xiangtan University, Hunan, Xiangtan 411105 (China)

    2011-09-01

    Highlights: > Bi{sub 2}VO{sub 5}F has been prepared by solid-state method. > The electrochemical behaviors of Bi{sub 2}VO{sub 5}F have been studied. > Bi{sub 2}VO{sub 5}F prepared at 550 deg. C shows good electrochemical performances. - Abstract: Bismuth-vanadium oxyfluoride (Bi{sub 2}VO{sub 5}F) has been synthesized using a simple, solid-state reaction process at different sintering temperatures. The structure and performance of the samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge experiments. The results show that bismuth-vanadium oxyfluoride belongs to a tetragonal crystal system with space group I4mm. The sample that was synthesized at 550 deg. C (P550) exhibits relatively good electrochemical properties. Sample P550 shows a high, initial discharge capacity of 222 mAh g{sup -1} at a rate of 100 mA g{sup -1} between 1.4 and 3.5 V. Sample P550 also shows acceptable electrochemical cycling properties. After the first cycle, the discharge specific capacity remains between 106 and 155 mAh g{sup -1}, which plateaus between 2.1 and 1.9 V during the first 15 cycles.

  14. Novel high-activity catalysts for partial oxidation of methane to formaldehyde

    CSIR Research Space (South Africa)

    Parmaliana, A

    1993-05-07

    Full Text Available Vanadium oxide-silica catalysts can effect the partial oxidation of methane to formaldehyde with extremely high activities and the space time yield (STY) can reach a value in excess of 800 g kg-1cat h-1; bare silica also shows appreciable STY value...

  15. Progress on the mechanistic understanding of SO2 oxidation catalysts

    DEFF Research Database (Denmark)

    Lapina, Olga B.; Bal'zhinimaev, B.S.; Boghosian, Soghomon

    1999-01-01

    For almost a century vanadium oxide based catalysts have been the dominant materials in industrial processes for sulfuric acid production. A vast body of information leading to fundamental knowledge on the catalytic process was obtained by Academician [G.K. Boreskov, Catalysis in Sulphuric Acid...

  16. High performance fuel electrode for a solid oxide electrochemical cell

    DEFF Research Database (Denmark)

    2013-01-01

    perovskite oxides selected from the group consisting of niobium-doped strontium titanate, vanadium-doped strontium titanate, tantalum-doped strontium titanate and mixtures thereof, thereby obtaining a porous anode backbone, (b) sintering the coated electrolyte at a high temperature, such as 1200 DEG C...

  17. Processing of Egyptian boiler-ash for extraction of vanadium and nickel.

    Science.gov (United States)

    Amer, A M

    2002-01-01

    Proposed technique in this investigation is given for vanadium and nickel enrichment in the Egyptian boiler ash. Among the various concepts for recovery of vanadium and nickel from boiler ash, the pyro-metallurgical approach is technically feasible, but is not cost-effective from an operational economy standpoint. Another technically viable process which, however, needs further development and presented in this investigation, is the hydrometallurgical processing that involves acid leaching under oxygen pressure of ground ash, followed by electrolytic separation of nickel from sulphate solution and vanadium is then neutralized and precipitated by adjustment the pH value and calcined to produce V2O5.

  18. Determination of traces of vanadium with 5-bromosalicylhydroxamic acid by solid-phase spectrophotometry

    Energy Technology Data Exchange (ETDEWEB)

    Pascual-Reguera, M.I.; Molina-Diaz, A.; Ramos-Martos, N. (Univ. of Granada, Jaen (Spain)); Capitan-Vallvey, L.F. (Univ. of Granada (Spain))

    1991-12-01

    A microdetermination method at {mu}g.1{sup {minus}1} levels for vanadium by solid-phase spectrophotometry has been developed. 5-Bromosalicylhydroxamic acid was used as chromogenic reagent to form a 1:2 violet complex which is easily sorbed and concentrated on a dextran-type anion-exchange resin. The resin-phase absorbances at 560 and 850 nm were measured directly. Vanadium can be determined in the 5-60 {mu}g.1{sup {minus}1} range with a RSD of 4.3%. The method is applied to the determination of vanadium in petroleum crudes and natural water samples.

  19. A comparison of hypoglycemic activity of three species of basidiomycetes rich in vanadium.

    Science.gov (United States)

    Han, Chunchao; Liu, Tongjun

    2009-02-01

    The hypoglycemic activity of fermented mushroom of three fungi of basidiomycetes rich in vanadium was studied in this paper. Alloxan- and adrenalin-induced hyperglycemic mice were used in the study. The blood glucose and the sugar tolerance were determined. After the mice were administered (ig) with Coprinus comatus rich in vanadium, the blood glucose of alloxan-induced hyperglycemic mice decreased (p Coprinus comatus rich in vanadium on hyperglycemic animals are significant; it may be used as a hypoglycemic food or medicine for hyperglycemic people.

  20. HF/H2O2 treated graphite felt as the positive electrode for vanadium redox flow battery

    Science.gov (United States)

    He, Zhangxing; Jiang, Yingqiao; Meng, Wei; Jiang, Fengyun; Zhou, Huizhu; Li, Yuehua; Zhu, Jing; Wang, Ling; Dai, Lei

    2017-11-01

    In order to improve the electrochemical performance of the positive graphite felt electrode in vanadium flow redox battery, a novel method is developed to effectively modify the graphite felt by combination of etching of HF and oxidation of H2O2. After the etching of HF for the graphite felt at ambient temperature, abundant oxygen-containing functional groups were further introduced on the surface of graphite felt by hydrothermal treatment using H2O2 as oxidant. Benefiting from the surface etching and introduction of functional groups, mass transfer and electrode process can be improved significantly on the surface of graphite felt. VO2+/VO2+ redox reaction on the graphite felt modified by HF and H2O2 jointly (denote: GF-HF/H2O2) exhibits superior electrochemical kinetics in comparison with the graphite felt modified by single HF or H2O2 treatment. The cell using GF-HF/H2O2 as the positive electrode was assembled and its electrochemical properties were evaluated. The increase of energy efficiency of 4.1% for GF-HF/H2O2 at a current density of 50 mA cm-2 was obtained compared with the pristine graphite felt. The cell using GF-HF/H2O2 also demonstrated higher discharge capacity. Our study revealed that HF/H2O2 treatment is an efficient method to enhance the electrochemical performance of graphite felt, further improving the comprehensive energy storage performance of the vanadium flow redox battery.

  1. Improved performance of organic light-emitting diode with vanadium pentoxide layer on the FTO surface

    Science.gov (United States)

    Saikia, D.; Sarma, R.

    2017-06-01

    Vanadium pentoxide layer deposited on the fluorine-doped tin oxide (FTO) anode by vacuum deposition has been investigated in organic light-emitting diode (OLED). With 12 nm optimal thickness of V2O5, the luminance efficiency is increased by 1.66 times compared to the single FTO-based OLED. The improvement of current efficiency implies that there is a better charge injection and better controlling of hole current. To investigate the performance of OLED by the buffer layer, V2O5 films of different thicknesses were deposited on the FTO anode and their J- V and L- V characteristics were studied. Further analysis was carried out by measuring sheet resistance, optical transmittance and surface morphology with the FE-SEM images. This result indicates that the V2O5 (12 nm) buffer layer is a good choice for increasing the efficiency of FTO-based OLED devices within the tunnelling region. Here the maximum value of current efficiency is found to be 2.83 cd / A.

  2. Overcoming Peak Overlaps in Titanium- and Vanadium-Bearing Materials with Multiple Linear Least Squares Fitting.

    Science.gov (United States)

    Mengason, Michael; Ritchie, Nicholas

    2017-06-01

    The evolution of the energy dispersive spectrometer (EDS) from the lithium-drifted silicon detector [Si(Li)] to the silicon drift detector (SDD) has created new opportunities in the field of electron probe X-ray microanalysis. The SDD permits operation at significantly higher count rates than the Si(Li) and also provides a more stable energy scale. X-ray spectra captured by EDS can now be analyzed qualitatively or quantitatively under the same beam conditions as used for wavelength dispersive spectrometry (WDS). Standards-based quantitative EDS (SB-Quant-EDS) can thus provide analyses that are accurate and precise for an ever growing number of materials measurement problems. In this study, we analyze NIST research glasses with "known" nominal concentrations of titanium (Ti) and vanadium (V) to evaluate the external reproducibility of the SB-Quant-EDS technique in the presence of severe peak overlaps. We additionally analyze several naturally occurring oxide minerals by WDS and EDS simultaneously and evaluate the outputs of these two methods when quantifying the same analytical volume within the sample.

  3. Large phonon entropy drives the metallization of vanadium dioxide (VO2)

    Science.gov (United States)

    Hong, Jiawang

    2015-03-01

    Vanadium dioxide (VO2) exhibits a first-order metal-insulator transition (MIT) near room temperature, where conductivity is suppressed and the lattice changes from tetragonal to monoclinic on cooling. This MIT in VO2 has attracted intense interest from both fundamental and technological perspectives. However, most studies performed in the past 50 years have focused on the electronic structure and energetics of the transition, ignoring the role of phonons and their entropic contribution to the phase stability. Much of the reason is that the standard tool of neutron scattering does not yield coherent scattering from V nuclei, and first-principles methods with harmonic approximation cannot capture the stable phonons for the rutile phase. We close this gap by using a combination of ab initio molecular dynamics calculations and neutron/x-ray scattering to establish that the entropy driving the MIT is dominated by soft, anharmonic phonons of the metallic phase. The MIT results from the competition between lower electronic energy in insulating M1 phase due to the Peierls instability, and the higher entropy of the metallic rutile phase resulting from soft anharmonic phonons. This understanding of the role of lattice dynamics and their relationship to electronic structure provides a critical component for developing more complete physical models of phase competition in functional transition metal oxides. Theoretical calculations were performed using the NERSC at LBNL. Modeling of neutron data was performed in CAMM, measurements were funded by the US DOE, BES, Materials Science and Engineering Division.

  4. Evolution of the vanadium pentoxide V2O5 crystal surface after vacuum annealing

    Science.gov (United States)

    Muslimov, A. E.; Butashin, A. V.; Valeev, R. G.; Sulyanov, S. N.; Beltiukov, A. N.; Kolymagin, A. B.; Babaev, V. A.; Kanevsky, V. M.

    2017-09-01

    A complex study of the (001) cleavage surface of a V2O5 single crystal annealed in vacuum at 450 and 550°C has been performed. Tunnel microscopy of the sample surface annealed in vacuum at 550°C showed the formation of a plane with a corundum structure, reconstructed according to the V2O3 (0001)-(1/√3 × 1/√3) R30° type, on the surface. X-ray photoelectron spectroscopy revealed a significant modification of interatomic bonds in the surface layers of V2O5 single crystal after vacuum annealing at 550°C, which is related to the partial reduction of V5+ ions and formation of lower vanadium oxides. These modifications lead to a decrease in the electrical resistivity of V2O5 and the occurrence of bending at a temperature of 61.5°C in the temperature dependence of the sample resistance, which is indicative of phase transition.

  5. Kinetic enhancement via passive deposition of carbon-based nanomaterials in vanadium redox flow batteries

    Science.gov (United States)

    Aaron, Doug; Yeom, Sinchul; Kihm, Kenneth D.; Ashraf Gandomi, Yasser; Ertugrul, Tugrul; Mench, Matthew M.

    2017-10-01

    Addition of carbon-based nanomaterials to operating flow batteries accomplishes vanadium redox flow battery performance improvement. Initial efforts focus on addition of both pristine graphene and vacuum-filtered reduced graphene oxide (rGO) film on carbon paper supporting electrodes. While the former is unable to withstand convective flow through the porous electrode, the latter shows measurable kinetic improvement, particularly when laid on the polymer electrolyte membrane (PEM) side of the electrode; in contrast to the kinetic performance gain, a deleterious impact on mass transport is observed. Based on this tradeoff, further improvement is realized using perforated rGO films placed on the PEM side of the electrodes. Poor mass transport in the dense rGO film prompts identification of a more uniform, passive deposition method. A suspension of rGO flakes or Vulcan carbon black (XC-72R), both boasting two orders-of-magnitude greater specific surface area than that of common carbon electrodes, is added to the electrolyte reservoirs and allowed to passively deposit on the carbon paper or carbon felt supporting electrodes. For common carbon felt electrodes, addition of rGO flakes or XC-72R enables a tripling of current density at the same 80% voltage efficiency.

  6. Alternative Processes for Manufacturing of Metal Oxide-based Potentiometric Chemosensors

    Directory of Open Access Journals (Sweden)

    Winfried VONAU

    2015-10-01

    Full Text Available New possibilities for the preparation of partially selective redox electrodes based on passivated metals of the subgroups IV to VI of the periodic system are presented by the example of vanadium. The gas phase oxidation at controlled oxygen partial pressures (CPO and the pulsed laser deposition (PLD as an high-vacuum method are utilised as alternative methods beside the well- established chemical and electrochemical passivation which usually lead to the highest possible oxidation state of the passivated metal. These newly available methods enable in principle the tailoring of oxidation states in the sensitive layer and therefore the optimisation of the electrochemical sensitivity and selectivity of sensors equipped with it. The use of vanadium as basic electrode material is crucial because it shows in several matrices a remarkable corrosion susceptibility. This problem can be solved by the introduction of stable alloys with high vanadium contents. These materials can be efficiently produced by pulsed laser deposition (PLD.

  7. Enhanced photocatalytic activity of hydrogenated and vanadium doped TiO2 nanotube arrays grown by anodization of sputtered Ti layers

    Science.gov (United States)

    Motola, Martin; Satrapinskyy, Leonid; Čaplovicová, Mária; Roch, Tomáš; Gregor, Maroš; Grančič, Branislav; Greguš, Ján; Čaplovič, Ľubomír; Plesch, Gustav

    2018-03-01

    TiO2 nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of titanium films sputtered by magnetron. To improve the photocatalytic activity of arrays annealed in air (o-TiNT), doping of o-TiNT with vanadium was performed (o-V/TiNT). These non-doped and doped TiNT arrays were also hydrogenated in H2/Ar atmosphere to r-TiNT and r-V/TiNT samples, respectively. Investigation of composition and morphology by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS) showed the presence of well-ordered arrays of anatase nanotubes with average diameter and length of 100 nm and 1.3 μm, respectively. In both oxidized and reduced V-doped samples, vanadium is partly dissolved in the structure of anatase and partly deposited in form of oxide on the nanotube surface. Vanadium-doped and reduced samples exhibited higher rates in the photodegradation of organic dyes (compared to non-modified o-TiNT sample) and this is caused by limitation of electron-hole recombination rates and by shift of the energy gap into visible region. The photocatalytic activity was measured under UV, sunlight and visible irradiation, and the corresponding efficiency increased in the order (o-TiNT) < (r-TiNT) < (o-V/TiNT) < (r-V/TiNT). Under visible light, only r-TiNT and r-V/TiNT showed significant photocatalytic activity.

  8. The Integration of a Structural Water Gas Shift Catalyst with a Vanadium Alloy Hydrogen Transport Device

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    This project is in response to a requirement for a system that combines water gas shift technology with separation technology for coal derived synthesis gas. The justification of such a system would be improved efficiency for the overall hydrogen production. By removing hydrogen from the synthesis gas stream, the water gas shift equilibrium would force more carbon monoxide to carbon dioxide and maximize the total hydrogen produced. Additional benefit would derive from the reduction in capital cost of plant by the removal of one step in the process by integrating water gas shift with the membrane separation device. The answer turns out to be that the integration of hydrogen separation and water gas shift catalysis is possible and desirable. There are no significant roadblocks to that combination of technologies. The problem becomes one of design and selection of materials to optimize, or at least maximize performance of the two integrated steps. A goal of the project was to investigate the effects of alloying elements on the performance of vanadium membranes with respect to hydrogen flux and fabricability. Vanadium was chosen as a compromise between performance and cost. It is clear that the vanadium alloys for this application can be produced, but the approach is not simple and the results inconsistent. For any future contracts, large single batches of alloy would be obtained and rolled with larger facilities to produce the most consistent thin foils possible. Brazing was identified as a very likely choice for sealing the membranes to structural components. As alloying was beneficial to hydrogen transport, it became important to identify where those alloying elements might be detrimental to brazing. Cataloging positive and negative alloying effects was a significant portion of the initial project work on vanadium alloying. A water gas shift catalyst with ceramic like structural characteristics was the second large goal of the project. Alumina was added as a

  9. A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

    Science.gov (United States)

    Alvarado-Gámez, Ana Lorena; Alonso-Lomillo, María Asunción; Domínguez-Renedo, Olga; Arcos-Martínez, María Julia

    2014-01-01

    A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 μM, a repeatability of 7.7% (n = 4) and a reproducibility of 8% (n = 3). A study of the possible interferences shows that the presence of Mo(VI), Cr(III), Ca(II) and W(VI), may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water. PMID:24569772

  10. A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

    Directory of Open Access Journals (Sweden)

    Ana Lorena Alvarado-Gámez

    2014-02-01

    Full Text Available A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 µM, a repeatability of 7.7% (n = 4 and a reproducibility of 8% (n = 3. A study of the possible interferences shows that the presence of Mo(VI, Cr(III, Ca(II and W(VI, may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water.

  11. The Importance of Vanadium Concentration in Ground and Deep Ground Water for Spring Water Quality

    National Research Council Canada - National Science Library

    MARCZEWSKI, Krzysztof; MARCZEWSKA, Barbara; KUZIOŁA, RAFA

    2015-01-01

      Vanadium, depending on the consumed dose may be toxic or health-promoting. Therefore, the knowledge of its concentration in the drinking therapeutic water, in particular in the medicinal mineral sources seems to be very important...

  12. The extraction of vanadium pentoxide from waste of titanium tetrachloride by various methods

    Directory of Open Access Journals (Sweden)

    Инна Михайловна Гунько

    2015-04-01

    Full Text Available In article the recovery possibility of vanadium pentoxide from wastes, formed as a result of purification from impurities of technical titanium tetrachloride is researched. The purification from impurities is realized by different methods – pulp of lower titanium chlorides, hydrocarbonic reducer and cascade-rectifying purification. Usage of these purification methods leads to formation of anthropogenic wastes. The researches is shown that processing of these wastes is reasonable for the purpose of vanadium pentoxide extraction

  13. Benchmark experiment on vanadium assembly with D-T neutrons. Leakage neutron spectrum measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kokooo; Murata, I.; Nakano, D.; Takahashi, A. [Osaka Univ., Suita (Japan); Maekawa, F.; Ikeda, Y.

    1998-03-01

    The fusion neutronics benchmark experiments have been done for vanadium and vanadium alloy by using the slab assembly and time-of-flight (TOF) method. The leakage neutron spectra were measured from 50 keV to 15 MeV and comparison were done with MCNP-4A calculations which was made by using evaluated nuclear data of JENDL-3.2, JENDL-Fusion File and FENDL/E-1.0. (author)

  14. A Novel Eco-Friendly Vanadium Precipitation Method by Hydrothermal Hydrogen Reduction Technology

    Directory of Open Access Journals (Sweden)

    Guobin Zhang

    2017-09-01

    Full Text Available In view of the serious pollution problems caused by the traditional vanadium precipitation process, the eco-friendly technology of hydrothermal hydrogen reduction was first applied to precipitate phase pure vanadium sesquioxide (V2O3 products from stripped pentavalent vanadium (V (V solution extracted from vanadium-bearing shale. Thermodynamic analysis demonstrate the method of hydrothermal hydrogen reduction is feasible for precipitating V2O3 from V (V solution at a suitable pH range, and the reduction should better be carried out at a lower pH under the pH range in which V2O3 can exist stably. The V2O3 products of 99.92% in purity and a high vanadium precipitation percentage of 99.25% were achieved under a facile reaction condition of initial solution pH of 6, reaction temperature of 523 K, H2 partial pressure of 4 MPa and reaction time of 2 h. Based on the analysis of XRD and FE-SEM with EDS for the precipitation products obtained at serial reaction times, the phase transformation mechanism was summarized to serial reductions with the phase transformation of HxVyOz(2z−x−5y− → NaV2O5 → VO2(H2O0.5 → VOOH → V2O3. Compared with the two-step traditional method of precipitating vanadium with ammonium salt and roast-reduction (react at above 773 K for more than 3 h for preparing V2O3, this method only experiences one-step reduction under a green atmosphere of H2 gas with a lower reaction temperature of 523 K and a shorter reaction time of 2h. Therefore, this method for vanadium precipitation is characterized by being eco-friendly, having a short process and being low-energy consumption, which has great significance for the sustainable development of vanadium industry.

  15. Factors controlling enrichment of vanadium and nickel in the bitumen of organic sedimentary rocks

    Energy Technology Data Exchange (ETDEWEB)

    Lewan, M.D. (Amoco Production Co., Tulsa, OK); Maynard, J.B.

    1982-12-01

    Enriched concentrations of vanadium and nickel have been noted in a variety of naturally occurring organic substances including crude oils, asphalts, and organic matter in some sedimentary rocks. Vanadium and nickel concentrations in bitumens extracted from a variety of organic sedimentary rock types of different geological ages and geographical areas range from less than 0.2 to 4760 ppm and less than 7 to 1240 ppm, respectively. Vanadium concentrations showed a polymodal frequency distribution. The concentrations of these two metals showed no significant correlations with bitumen content, organic carbon content, or proportionality between bitumen and organic carbon contents. Enriched vanadium and nickel concentrations greater than 100 ppm are only observed in bitumens that are associated with Type II and Type I kerogens. Conversely, bitumens associated with Type III kerogens contained vanadium and nickel concentrations less than 100 ppm. The high stability of vanadium and nickel in crude oils, asphalts, and bitumens suggest that they occur in tetrapyrrole complexes. The complexes may occur as free molecules or assimulated subunits in macromolecules within the bitumen. Vanadium and nickel are preferentially concentrated in tetrapyrrole complexes because of their availability in anaerobic systems, small atomic radii, and favorable electron configurations. The potential for an organic sediment to be enriched in these two metals depends upon the amount of tetrapyrroles preserved in its organic matter. Tetrapyrrole preservation preferentially decreases in organic matter as exposure time to aerobic conditions increases. The potential for vanadium and nickel enrichment is therefore the highest in organic matter derived from algae that encountered anaerobic conditions early in their depositional history.

  16. One-pot synthesis of optically active allyl esters via lipase-vanadium combo catalysis.

    Science.gov (United States)

    Akai, Shuji; Hanada, Ryosuke; Fujiwara, Noboru; Kita, Yasuyuki; Egi, Masahiro

    2010-11-05

    The combination of vanadium-oxo compounds (3 or 4) with a lipase produced the regio- and enantioconvergent transformation of racemic allyl alcohols (1 or 2) into optically active allyl esters. In this system, the vanadium compounds catalyzed the continuous racemization of the alcohols along with the transposition of the hydroxyl group, while the lipase effected the chemo- and enantioselective esterification to achieve the dynamic kinetic resolution.

  17. Temperature Dependence of Uranium and Vanadium Adsorption on Amidoxime-Based Adsorbents in Natural Seawater

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Li-Jung [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Gill, Gary A. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Tsouris, Costas [Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Rao, Linfeng [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA; Pan, Horng-Bin [Department of Chemistry, University of Idaho, Moscow ID 83844 USA; Wai, Chien M. [Department of Chemistry, University of Idaho, Moscow ID 83844 USA; Janke, Christopher J. [Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Strivens, Jonathan E. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Wood, Jordana R. [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; Schlafer, Nicholas [Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim WA 98382 USA; D' Alessandro, Evan K. [Rosensteil School of Marine and Atmospheric Chemistry, University of Miami, Miami FL 33149 USA

    2018-01-16

    The apparent enthalpy and entropy of the complexation of uranium (VI) and vanadium (V) with amidoxime ligands grafted onto polyethylene fiber was determined using time series measurements of adsorption capacities in natural seawater at three different temperatures. The complexation of uranium was highly endothermic, while the complexation of vanadium showed minimal temperature sensitivity. Amidoxime-based polymeric adsorbents exhibit significantly increased uranium adsorption capacities and selectivity in warmer waters.

  18. Simulation of vanadium-48 production using MCNPX code

    Directory of Open Access Journals (Sweden)

    Sadeghi Mahdi

    2012-01-01

    Full Text Available Vanadium-48 was produced through the irradiation of the natural titanium target via the natTi(p, xn48V reaction. The titanium target was irradiated at 1 mA current and by a 21 MeV proton beam for 4 hours. In this paper, the activity of 48V, 43Sc, and 46Sc radionuclides and the efficacy of the 47Ti(p, g, 48Ti(p, n, and 49Ti(p, 2n channel reactions to form 48V radionuclide were determined using MCNPX code. Furthermore, the experimental activity of 48V was compared with the estimated value for the thick target yield produced in the irradiation time according to MCNPX code. Good agreement between production yield of the 48V and the simulation yield was observed. In conclusion, MCNPX code can be used for the estimation of the production yield.

  19. Determining the Limiting Current Density of Vanadium Redox Flow Batteries

    Directory of Open Access Journals (Sweden)

    Jen-Yu Chen

    2014-09-01

    Full Text Available All-vanadium redox flow batteries (VRFBs are used as energy storage systems for intermittent renewable power sources. The performance of VRFBs depends on materials of key components and operating conditions, such as current density, electrolyte flow rate and electrolyte composition. Mass transfer overpotential is affected by the electrolyte flow rate and electrolyte composition, which is related to the limiting current density. In order to investigate the effect of operating conditions on mass transport overpotential, this study established a relationship between the limiting current density and operating conditions. First, electrolyte solutions with different states of charge were prepared and used for a single cell to obtain discharging polarization curves under various operating conditions. The experimental results were then analyzed and are discussed in this paper. Finally, this paper proposes a limiting current density as a function of operating conditions. The result helps predict the effect of operating condition on the cell performance in a mathematical model.

  20. Geometric constraints on phase coexistence in vanadium dioxide single crystals.

    Science.gov (United States)

    McGahan, Christina; Gamage, Sampath; Liang, Jiran; Cross, Brendan; Marvel, Robert E; Haglund, Richard F; Abate, Yohannes

    2017-02-24

    The appearance of stripe phases is a characteristic signature of strongly correlated quantum materials, and its origin in phase-changing materials has only recently been recognized as the result of the delicate balance between atomic and mesoscopic materials properties. A vanadium dioxide (VO2) single crystal is one such strongly correlated material with stripe phases. Infrared nano-imaging on low-aspect-ratio, single-crystal VO2 microbeams decorated with resonant plasmonic nanoantennas reveals a novel herringbone pattern of coexisting metallic and insulating domains intercepted and altered by ferroelastic domains, unlike previous reports on high-aspect-ratio VO2 crystals where the coexisting metal/insulator domains appear as alternating stripe phases perpendicular to the growth axis. The metallic domains nucleate below the crystal surface and grow towards the surface with increasing temperature as suggested by the near-field plasmonic response of the gold nanorod antennas.

  1. Gas tungsten arc welding of vanadium alloys with impurity control

    Science.gov (United States)

    Grossbeck, M. L.; King, J. F.; Nagasaka, T.; David, S. A.

    2002-12-01

    Gas tungsten arc welding in vanadium alloys is controlled by interstitial impurities. Techniques have been developed to weld V-4Cr-4Ti in a high-purity argon atmosphere resulting in a DBTT of -20 °C. The atmosphere was controlled by a Zr-Al getter which is activated at high temperature to obtain a clean surface then cooled and allowed to absorb hydrogen and oxygen impurities. Through the use of low-oxygen base metal and high-purity weld filler wire, a DBTT of -145 °C was obtained. Experiments using electron beam welding have shown that grain size also has an important effect on weld ductility. Introduction of nitrogen and yttrium has been used to study their effect on grain size. Using a combination of atmosphere control, alloy purity control, and grain size control, it is anticipated that V-Cr-Ti alloys will be weldable in field conditions.

  2. Neural Network Predictive Control for Vanadium Redox Flow Battery

    Directory of Open Access Journals (Sweden)

    Hai-Feng Shen

    2013-01-01

    Full Text Available The vanadium redox flow battery (VRB is a nonlinear system with unknown dynamics and disturbances. The flowrate of the electrolyte is an important control mechanism in the operation of a VRB system. Too low or too high flowrate is unfavorable for the safety and performance of VRB. This paper presents a neural network predictive control scheme to enhance the overall performance of the battery. A radial basis function (RBF network is employed to approximate the dynamics of the VRB system. The genetic algorithm (GA is used to obtain the optimum initial values of the RBF network parameters. The gradient descent algorithm is used to optimize the objective function of the predictive controller. Compared with the constant flowrate, the simulation results show that the flowrate optimized by neural network predictive controller can increase the power delivered by the battery during the discharge and decrease the power consumed during the charge.

  3. Development of laser welding techniques for vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Strain, R.V.; Leong, K.H.; Smith, D.L.

    1996-04-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Lasers do not require a vacuum (as do electron beam welders) and the welds they produce high depth-to-width ratios. Scoping with a small pulsed 50 J YAG laser indicated that lasers could produce successful welds in vanadium alloy (V-5%Cr-5%Ti) sheet (1 mm thick) when the fusion zone was isolated from air. The pulsed laser required an isolating chamber filled with inert gas to produce welds that did not contain cracks and showed only minor hardness increases. Following the initial scoping tests, a series of tests were preformed with a 6 kW continuous CO{sub 2} laser. Successful bead-on-plate welds were made on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys to depths of about 4 mm with this laser.

  4. Optical modulation in silicon-vanadium dioxide photonic structures

    Science.gov (United States)

    Miller, Kevin J.; Hallman, Kent A.; Haglund, Richard F.; Weiss, Sharon M.

    2017-08-01

    All-optical modulators are likely to play an important role in future chip-scale information processing systems. In this work, through simulations, we investigate the potential of a recently reported vanadium dioxide (VO2) embedded silicon waveguide structure for ultrafast all-optical signal modulation. With a VO2 length of only 200 nm, finite-differencetime- domain simulations suggest broadband (200 nm) operation with a modulation greater than 12 dB and an insertion loss of less than 3 dB. Predicted performance metrics, including modulation speed, modulation depth, optical bandwidth, insertion loss, device footprint, and energy consumption of the proposed Si-VO2 all-optical modulator are benchmarked against those of current state-of-the-art all-optical modulators with in-plane optical excitation.

  5. Electron-beam deposition of vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Marvel, R.E.; Appavoo, K. [Vanderbilt University, Interdisciplinary Materials Science Program, Nashville, TN (United States); Choi, B.K. [Vanderbilt University, Department of Electrical Engineering and Computer Science, Nashville, TN (United States); Nag, J. [Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States); Haglund, R.F. [Vanderbilt University, Interdisciplinary Materials Science Program, Nashville, TN (United States); Vanderbilt University, Institute for Nanoscale Science and Engineering, Nashville, TN (United States); Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States)

    2013-06-15

    Developing a reliable and efficient fabrication method for phase-transition thin-film technology is critical for electronic and photonic applications. We demonstrate a novel method for fabricating polycrystalline, switchable vanadium dioxide thin films on glass and silicon substrates and show that the optical switching contrast is not strongly affected by post-processing annealing times. The method relies on electron-beam evaporation of a nominally stoichiometric powder, followed by fast annealing. As a result of the short annealing procedure we demonstrate that films deposited on silicon substrates appear to be smoother, in comparison to pulsed laser deposition and sputtering. However, optical performance of e-beam evaporated film on silicon is affected by annealing time, in contrast to glass. (orig.)

  6. Tc anisotropy and phase separation in strained Vanadium Dioxide films

    Science.gov (United States)

    Liu, Mengkun; Wagner, Martin; Abreu, Elsa; Kittiwatanakul, Salinporn; McLeod, Alexander; Goldflam, Michael; Fei, Zhe; Dai, Siyuan; Fogler, Michael; Lu, Jiwei; Wolf, Stuart; Averitt, Richard; Basov, D. N.

    2013-03-01

    We report Infrared near field study on strain induced transition temperature (Tc) anisotropy in vanadium dioxide (VO2) films via direct visualization of a spontaneous structural and electronic phase separation. The films are epitaxially grown on [110]R or [100]R TiO2 substrates and exhibit large uniaxial strain. By mapping the film topography with AFM and electronic percolation with Infrared scattering scanning near-field optical microscopy, a temperature dependent electron-lattice correlation can be clearly observed. Our work sheds a new light onto the nature of the Tc anomaly in metal-insulator transition and leads to the possibility of controlling the material's properties through strain induced phase separation.

  7. Molecular dynamics simulation of deformation twin in rocksalt vanadium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Tao [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Peng, Xianghe, E-mail: xhpeng@cqu.edu.cn [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044 (China); Zhao, Yinbo [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Li, Tengfei [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Li, Qibin [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Wang, Zhongchang, E-mail: zcwang@wpi-aimr.tohoku.ac.jp [College of Aerospace Engineering, Chongqing University, Chongqing 400044 (China); Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2016-08-05

    We perform molecular dynamics simulation of nano-indentation with a cylindrical indenter to investigate the formation mechanism of deformation twin in vanadium nitride (VN) with a rocksalt structure. We find that the deformation twins occur during the loading stage, and subsequently conduct a systematic analysis of nucleation, propagation and thickening of a deformation twin. We find that the nucleation of a partial dislocation and its propagation to form a stacking fault are premise of deformation twin formation. The sequential nucleation and propagation of partial dislocation on adjacent parallel {111} planes are found to cause the thickening of the deformation twin. Moreover, the deformation twins can exist in VN at room temperature. - Highlights: • MD simulations of indentation are performed to study the deformation twin in VN. • The deformation twins can occur in VN during the loading stage. • The nucleation, propagation and thickening of a deformation twin are analyzed. • The deformation twins can exist in VN at room temperature.

  8. Selective determination of total vanadium in water samples by cloud point extraction of its ternary complex.

    Science.gov (United States)

    Filik, Hayati; Yanaz, Zeynep; Apak, Reşat

    2008-07-14

    A highly sensitive micelle-mediated extraction methodology for the preconcentration of trace levels of vanadium as a prior step to its determination by flame atomic absorption spectrometry (FAAS) has been developed. Vanadium was complexed with 1-(2-pyridylazo)-2-naphthol (PAN) and hydrogen peroxide in acidic medium (0.2 mol L(-1) phosphoric acid) using Triton X-100 as surfactant and quantitatively extracted into a small volume of the surfactant-rich phase after centrifugation. The color reaction of vanadium ions with hydrogen peroxide and PAN in phosphoric acid medium is highly selective. The chemical variables affecting cloud point extraction (CPE) were evaluated and optimized. The R.S.D. for 5 replicate determinations at the 20 microg L(-1)V level was 3.6%. The calibration graph using the preconcentration system for vanadium was linear with a correlation coefficient of 0.99 at levels near the detection limits up to at least 0.6 microg L(-1). The method has good sensitivity and selectivity and was applied to the determination of trace amounts of vanadium in water samples with satisfactory result. The proposed method is a rare application of CPE-atomic spectrometry to vanadium assay, and is superior to most other similar methods, because its useful pH range is in the moderately acidic range achieved with phosphoric acid. At this pH, many potential interferents are not chelated with PAN, and iron(III) as the major interferent is bound in a stable phosphate complex.

  9. A systematic review of vanadium oral supplements for glycaemic control in type 2 diabetes mellitus.

    Science.gov (United States)

    Smith, D M; Pickering, R M; Lewith, G T

    2008-05-01

    To assess the effectiveness of oral vanadium supplementation for glycaemic control in type 2 diabetes by conducting a systematic review of the literature. Eligible studies were identified by searching 14 databases using standardized terms. Experts, study authors and manufacturers were also contacted. Hand-searching was not undertaken. Selection criteria for inclusion in the review were controlled human trials of vanadium vs. placebo in adults with type 2 diabetes of minimum 2 months duration, and a minimum of 10 subjects per arm. Data extraction, assessment of study quality and outcome analysis were undertaken by two independent reviewers. One hundred and fifty one studies were found but none met the inclusion criteria. We proceeded to summarize the state of existing evidence and plan for a future clinical trial by applying revised, less restrictive criteria to our search, for clinical trials of 30-150 mg daily oral vanadium supplementation in diabetic humans. Only five were identified. These demonstrated significant treatment-effects, but due to poor study quality, must be interpreted with caution. Treatment with vanadium often results in gastrointestinal side-effects. There is no rigorous evidence that oral vanadium supplementation improves glycaemic control in type 2 diabetes. The routine use of vanadium for this purpose cannot be recommended. A large-scale randomized controlled trial is needed to address this clinical question.

  10. Expressed sequence tag analysis of vanadocytes in a vanadium-rich ascidian, Ascidia sydneiensis samea.

    Science.gov (United States)

    Yamaguchi, Nobuo; Kamino, Kei; Ueki, Tatsuya; Michibata, Hitoshi

    2004-01-01

    Some species in the family Ascidiidae accumulate vanadium at concentrations in excess of 350 mM, which corresponds to about 10(7) times higher than that in seawater. In these species signet ring cells, with a single huge vacuole in which vanadium ion is contained, function as vanadium-accumulating cells, vanadocytes. To investigate the mechanism underlying this phenomenon, we performed an expressed sequence tag (EST) analysis of a complementary DNA library from vanadocytes of a vanadium-rich ascidian, Ascidia sydneiensis samea. We determined the nucleotide sequences of 1000 ESTs and performed a BLAST analysis against the SwissProt database. We found 93 clones of metal-related gene homologues, including the ferritin heavy subunit, hemocyanin, and metallothionein. Two ESTs, in particular, exhibited significant similarity to vanabins that have been extracted from A. sydneiensis samea blood cells as low molecular weight vanadium-binding proteins. We have named the genes encoding these ESTs vanabin3 and vanabin4. Immobilized metal ion affinity chromatography revealed that these novel vanabin homologues bind vanadium(IV) ions.

  11. Current status and associated human health risk of vanadium in soil in China.

    Science.gov (United States)

    Yang, Jie; Teng, Yanguo; Wu, Jin; Chen, Haiyang; Wang, Guoqiang; Song, Liuting; Yue, Weifeng; Zuo, Rui; Zhai, Yuanzheng

    2017-03-01

    A detailed assessment of vanadium contamination characteristics in China was conducted based on the first national soil pollution survey. The map overlay analysis was used to evaluate the contamination level of vanadium and the non-carcinogenic risk assessment model was calculated to quantify the vanadium exposure risks to human health. The results showed that, due to the drastically increased mining and smelting activities, 26.49% of soils were contaminated by vanadium scattered in southwest of China. According to Canadian soil quality guidelines, about 8.6% of the national soil pollution survey samples were polluted, and pose high non-carcinogenic risks to the public, especially to children living in the vicinity of heavily polluted mining areas. We propose the area near the boundary of Yunnan, Guizhou, Guangxi, and Sichuan provinces as priority control areas due to their higher geochemical background or higher health risks posed to the public. Finally, recommendations for management are proposed, including minimization of contaminant inputs, establishing stringent monitoring program, using phytoremediation, and strengthening the enforcement of relevant laws. Therefore, this study provides a comprehensive assessment of soil vanadium contamination in China, and the results will provide valuable information for China's soil vanadium management and risk avoidance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Allergic reaction to vanadium causes a diffuse eczematous eruption and titanium alloy orthopedic implant failure.

    Science.gov (United States)

    Engelhart, Sally; Segal, Robert J

    2017-04-01

    Allergy as a cause of adverse outcomes in patients with implanted orthopedic hardware is controversial. Allergy to titanium-based implants has not been well researched, as titanium is traditionally thought to be inert. We highlight the case of a patient who developed systemic dermatitis and implant failure after surgical placement of a titanium alloy (Ti6Al4V) plate in the left foot. The hardware was removed and the eruption cleared in the following weeks. The plate and screws were submitted for metal analysis. The elemental composition of both the plate and screws included 3 major elements-titanium, aluminum, and vanadium-as well as trace elements. Metal analysis revealed that the plate and screws had different microstructures, and electrochemical studies demonstrated that galvanic corrosion could have occurred between the plate and screws due to their different microstructures, contributing to the release of vanadium in vivo. The patient was patch tested with several metals including components of the implant and had a positive patch test reaction only to vanadium trichloride. These findings support a diagnosis of vanadium allergy and suggests that clinicians should consider including vanadium when patch testing patients with a suspected allergic reaction to vanadium-containing implants.

  13. A novel comprehensive utilization of vanadium slag: As gamma ray shielding material.

    Science.gov (United States)

    Dong, Mengge; Xue, Xiangxin; Yang, He; Liu, Dong; Wang, Chao; Li, Zhefu

    2016-11-15

    New exploration of vanadium slag as gamma ray shielding material was proposed, the shielding properties of vanadium slag was higher than concrete when the energy of photons was in 0.0001MeV-100000MeV. Vanadium slag/epoxy resin composites were prepared, shielding and material properties of materials were tested by (60)Co gamma ray, simultaneous DSC-TGA, electronic universal testing machine and scanning electron microscopy, respectively. The results showed that the shielding properties of composite would be better with the increase of vanadium slag addition amount. The HVL (half value layer thickness) of vanadium slag was between Lead and concrete while composite was higher than concrete when the addition amount of vanadium slag was 900 used as material to shield (60)Co gamma ray, also the resistance temperature of composite was about 215°C and the bending strength was over 10MPa. The composites could be used as injecting mortar for cracks developed in biological concrete shields, coating for the floor of the nuclear facilities, and shielding materials by itself. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Surface and bulk aspects of mixed oxide catalytic nanoparticles: oxidation and dehydration of CH(3)OH by polyoxometallates.

    Science.gov (United States)

    Nakka, Lingaiah; Molinari, Julie E; Wachs, Israel E

    2009-10-28

    The molecular structures and surface chemistry of mixed metal oxide heteropolyoxo vanadium tungstate (H(3+x)PW(12-x)V(x)O(40) with x = 0, 1, 2, and 3) Keggin nanoparticles (NPs), where vanadium is incorporated into the primary Keggin structure, and supported VO(x) on tungstophosphoric acid (TPA, H(3)PW(12)O(40)), where vanadium is present on the surface of the Keggin unit, were investigated with solid-state magic angle spinning (51)V NMR, FT-IR, in situ Raman, in situ UV-vis, CH(3)OH temperature-programmed surface reaction (TPSR), and steady-state methanol oxidation. The incorporated VO(x) unit possesses one terminal V horizontal lineO bond, four bridging V-O-W/V bonds, and one long V-O-P bond in the primary Keggin structure, and the supported VO(x) unit possesses a similar coordination in the secondary structure under ambient conditions. The specific redox reaction rate for VO(x) in the Keggin primary structure is comparable to that of bulk V(2)O(5) and the more active supported vanadium oxide catalysts. The specific acidic reaction rate for the WO(x) in the TPA Keggin, however, is orders of magnitude greater than found for bulk WO(3), supported tungsten oxide catalysts, and even the highly acidic WO(3)-ZrO(2) catalyst synthesized by coprecipitation of ammonium metatungstate and ZrO(OH)(2). From CH(3)OH-TPSR and in situ Raman spectroscopy it was found that incorporation of vanadium oxide into the primary Keggin structure is also accompanied by the formation of surface VO(x) species at secondary sites on the Keggin outer surface. Both CH(3)OH-TPSR and steady-state methanol oxidation studies demonstrated that the surface VO(x) species on the Keggin outer surface are significantly less active than the VO(x) species incorporated into the primary Keggin structure. The presence of the less active surface VO(x) sites in the Keggins, thus, decreases the specific reaction rates for both methanol oxidation and methanol dehydration. During methanol oxidation/dehydration (O(2

  15. Lubrication with Naturally Occurring Double Oxide Films

    Science.gov (United States)

    1982-11-10

    Friction Test with Metal Powders 24 7. Diagram of Metal Powder Test Specimen 24 R. Effect of Temperature on the Friction Coefficient for 28 CuPRe...that chronates would be produced as a result of its oxidation; more likely chromites (MeO. Cr203). Vanadium and boron are used in small amounts for...the frictional process in an alloy. The metal asperities would act as the basic alloy structure or as harder phases in that structure since it would

  16. Detection of capacity imbalance in vanadium electrolyte and its electrochemical regeneration for all-vanadium redox-flow batteries

    Science.gov (United States)

    Roznyatovskaya, Nataliya; Herr, Tatjana; Küttinger, Michael; Fühl, Matthias; Noack, Jens; Pinkwart, Karsten; Tübke, Jens

    2016-01-01

    A vanadium electrolyte for redox-flow batteries (VRFB) with different VIII and VIV mole fractions has been studied by UV-vis spectroscopy. Spectrophotometric detection enables a rough estimate of the VIV and VIII content, which can be used to detect an electrolyte capacity imbalance, i.e. a deviation in the mole fraction of VIV or VIII away from 50%. The isosbestic point at 600 nm can be used as a reference point in the analysis of common VRFB electrolyte batches. The VRFB electrolyte is observed to have an imbalance after prolonged storage (a couple of years) in a tank under ambient conditions. A regeneration procedure, which involves pre-charging the unbalanced electrolyte and mixing part of it with a portion of initial unbalanced electrolyte, has been tested. The resulting rebalanced electrolyte has been compared with a common electrolyte in a charge-discharge cell test and is shown to be suitable for cell operation.

  17. The toxicity of vanadium on gastrointestinal, urinary and reproductive system, and its influence on fertility and fetuses malformations.

    Science.gov (United States)

    Wilk, Aleksandra; Szypulska-Koziarska, Dagmara; Wiszniewska, Barbara

    2017-09-25

    Vanadium is a transition metal that has a unique and beneficial effect on both humans and animals. For many years, studies have suggested that vanadium is an essential trace element. Its biological properties are of interest due to its therapeutic potential, including in the treatment of diabetes mellitus. Vanadium deficiencies can lead to a range of pathologies. However, excessive concentration of this metal can cause irreversible damage to various tissues and organs. Vanadium toxicity mainly manifests in gastrointestinal symptoms, including diarrhea, vomiting, and weight reduction. Vanadium also exhibits hepatotoxic and nephrotoxic properties, including glomerulonephritis and pyelonephritis. Vanadium compounds may also lead to partial degeneration of the seminiferous epithelium of the seminiferous tubules in the testes and can affect male fertility. This paper describes the harmful effects of vanadium on the morphology and physiology of both animal and human tissues, including the digestive system, the urinary tract, and the reproductive system. What is more, the following study includes data concerning the correlation between the above-mentioned metal and its influence on fertility and fetus malformations. Additionally, this research identifies the doses of vanadium which lead to pathological alterations becoming visible within tissues. Moreover, this study includes information about the protective efficacy of some substances in view of the toxicity of vanadium.

  18. Oxidation of o-xylene on mesoporous Ti-phosphate-supported VOx catalysts and promoter effect of K+ on selectivity

    NARCIS (Netherlands)

    Mérida-Robles, J.; Rodríguez-Castellón, E.; Jiménez-López, A.; López Granados, M.; Val, S. del; Melián Cabrera, I.; Fierro, J.L.G.; Jimenez, J

    2005-01-01

    The selective oxidation of o-xylene on catalysts based on mesoporous titanium phosphate-supported vanadium oxide has been studied. The catalysts were characterized by different physico-chemical techniques (XRD, XPS, N-2 isotherms, TPD of chemisorbed NH3 and Raman spectroscopy). The conversion and

  19. Effects of metal compounds with distinct physicochemical properties on iron homeostasis and antibacterial activity in the lungs: chromium and vanadium.

    Science.gov (United States)

    Cohen, Mitchell D; Sisco, Maureen; Prophete, Colette; Yoshida, Kotaro; Chen, Lung-chi; Zelikoff, Judith T; Smee, Jason; Holder, Alvin A; Stonehuerner, Jacqueline; Crans, Debbie C; Ghio, Andrew J

    2010-02-01

    In situ reactions of metal ions or their compounds are important mechanisms by which particles alter lung immune responses. The authors hypothesized that major determinants of the immunomodulatory effect of any metal include its redox behavior/properties, oxidation state, and/or solubility, and that the toxicities arising from differences in physicochemical parameters are manifest, in part, via differential shifts in lung iron (Fe) homeostasis. To test the hypotheses, immunomodulatory potentials for both pentavalent vanadium (VV; as soluble metavanadate or insoluble vanadium pentoxide) and hexavalent chromium (CrVI; as soluble sodium chromate or insoluble calcium chromate) were quantified in rats after inhalation (5h/day for 5 days) of each at 100 microg metal/m3. Differences in effects on local bacterial resistance between the two VV, and between each CrVI, agents suggested that solubility might be a determinant of in situ immunotoxicity. For the soluble forms, VV had a greater impact on resistance than CrVI, indicating that redox behavior/properties was likely also a determinant. The soluble VV agent was the strongest immunomodulant. Regarding Fe homeostasis, both VV agents had dramatic effects on airway Fe levels. Both also impacted local immune/airway epithelial cell Fe levels in that there were significant increases in production of select cytokines/chemokines whose genes are subject to regulation by HIF-1 (whose intracellular longevity is related to cell Fe status). Our findings contribute to a better understanding of the role that metal compound properties play in respiratory disease pathogenesis and provide a rationale for differing pulmonary immunotoxicities of commonly encountered ambient metal pollutants.

  20. Core-Shell Vanadium Modified Titania@β-In2S3 Hybrid Nanorod Arrays for Superior Interface Stability and Photochemical Activity.

    Science.gov (United States)

    Mumtaz, Asad; Mohamed, Norani Muti; Mazhar, Muhammad; Ehsan, Muhammad Ali; Mohamed Saheed, Mohamed Shuaib

    2016-04-13

    Core-shell rutile TiO2@β-In2S3 and modified V-TiO2@β-In2S3 were synthesized to develop bilayer systems to uphold charge transport via an effective and stable interface. Morphological studies revealed that β-In2S3 was deposited homogeneously on V-TiO2 as compared to unmodified TiO2 nanorod arrays. X-ray photoelectron spectroscopy (XPS) and electron energy loss spectrometry studies verified the presence of various oxidation states of vanadium in rutile TiO2 and the vanadium surface was utilized for broadening the charge collection centers in host substrate layer and hole quencher window. Subsequently, X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectra confirmed the rutile phases of TiO2 and modified V-TiO2 along with the phases of crystalline β-In2S3. XPS valence band study explored the interaction of valence band quazi Fermi levels of β-In2S3 with the conduction band quazi Fermi levels of modified V-TiO2 for enhanced charge collection at the interface. Photoelectrochemical studies show that the photocurrent density of V-TiO2@β-In2S3 is 1.42 mA/cm(2) (1.5AM illumination). Also, the frequency window for TiO2 was broadened by the vanadium modification in rutile TiO2 nanorod arrays, and the lifetime of the charge carrier and stability of the interface in V-TiO2@β-In2S3 were enhanced compared to the unmodified TiO2@β-In2S3. These findings highlight the significance of modifications in host substrates and interfaces, which have profound implications on interphase stability, photocatalysis and solar-fuel-based devices.

  1. A novel method to remove chromium, vanadium and ammonium from vanadium industrial wastewater using a byproduct of magnesium-based wet flue gas desulfurization.

    Science.gov (United States)

    Fang, Dean; Zhang, Xuefei; Dong, Mengge; Xue, Xiangxin

    2017-08-15

    A novel treatment for chromium, vanadium and ammonium from vanadium industrial wastewater using a byproduct of magnesium-based wet flue gas desulfurization is investigated. In the present study, the byproduct is used as a reductant for chromium and vanadium removal by chemical precipitation, and the residual magnesium ion can also be used to remove ammonium in the present of phosphate by struvite crystallization. Besides, the effects of main operational parameters (reaction pH, byproduct dosage and reaction time) on the heavy metal removal and ammonium removal (reaction pH, Mg(2+):NH4(+):PO4(3-) molar ratio and reaction time) are investigated, and the reaction mechanism for this treatment technology is also proposed. Under the optimal conditions, the residual concentrations of chromium(IV), total chromium and vanadium are 0.046mg/L, 0.468mg/L and 0.06mg/L, respectively. The removal efficiency of ammonium is 95.72% and the residual concentrations of ammonium and phosphorus are 137.12mg/L and 5.49mg/L, respectively. Additionally, the precipitations are characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and thermogravimetry differential scanning calorimetry (TG-DSC), respectively. Finally, a resource utilization method of the precipitation sludge from this technology is also presented. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Leaching of vanadium from sulphuric acid manufacture spent catalysts

    Directory of Open Access Journals (Sweden)

    García, Diego Juan

    2001-02-01

    Full Text Available Recovery of vanadium contained in spent catalysts from the manufacture of sulphuric acid has been studied in this work, resulting in an industrial multistage process for the treatment of them avoiding direct deposition or dumping. Characterization of supplied spent catalysts samples, confirmed vanadium levels showed in the literature. The study of variables influencing leaching process: type of leaching agent, leaching agent concentration, S/L ratio, stirring speed and temperature, allows to fix the most advantageous conditions using industrial application criterion and verifying that the process is difusión controlled. The work is completed by developing an industrial leaching cycle simulation with the aim of reproducing real performance of spent catalyst, proposing operating conditions, and verifying the non-toxic character of the final residue obtained.

    En el presente trabajo se ha estudiado la recuperación del vanadio contenido en los catalizadores agotados procedentes de la fabricación del ácido sulfúrico, planteando un proceso industrial multietapa para el tratamiento de estos residuos, evitando su deposición o vertido directos. La caracterización de las muestras de catalizadores agotados disponibles confirmó los valores encontrados en la bibliografía. Se estudiaron las variables que influyen en el proceso de lixiviación (tipo de agente de lixiviación y concentración del mismo, relación S/L, velocidad de agitación y temperatura definiendo las condiciones más adecuadas desde el punto de vista industrial y verificando que el proceso está controlado por mecanismos difusionales. El trabajo se completa con la simulación de un ciclo industrial de lavado del catalizador y la verificación de la nula toxicidad de los lixiviados obtenidos por degradación del residuo final. 24 Aplicación de la resistencia de ruido al estudio de pinturas ricas en zinc Noise resistance applied to the study of zinc rich paints

  3. El vanadio, un elemento ambiguo Vanadium, an ambiguous element

    Directory of Open Access Journals (Sweden)

    Graciela Beatriz García

    2006-12-01

    Full Text Available El vanadio (V se encuentra en 68 minerales diferentes, en los combustibles derivados del petróleo y el carbón y se utiliza principalmente en la industria metalúrgica. Para los humanos, la principal fuente de exposición al V es la contaminación atmosférica producida por la quema de combustibles. En los animales se ha demostrado que algunos compuestos del V son hepatotóxicos, nefrotóxicos, neurotóxicos, carcinogénicos y que afectan a la reproducción y al desarrollo de los fetos y lactantes. Sin embargo, los efectos toxicológicos finales, motivo de preocupación para las personas son la genotoxicidad y la irritación de las vías respiratorias. Por otra parte, los compuestos del V han sido objeto de investigación como agentes que disminuyen los niveles séricos de glucosa, como antihipertensivos, como anorexígenos y como anticancerígenos. El V, de efectos biológicos notables, debe ser más estudiado con el fin de conocer los mecanismos de su acción biológica y para poder determinar tanto los riesgos a su exposición como sus posibles usos farmacológicos en beneficio humano.Vanadium (V occurs in about 68 minerals and in fossil fuels and it is mainly used in steel industry. Air pollution produced by oil and coal burning is the main exposure source for human beings. Reproductive and developmental toxicity, hepatotoxicity, nephrotoxicity, neurotoxicity and carcinogenicity have been found in some vanadium compound exposed animals. Nevertheless, the toxicological end-points of concern for humans are genotoxicity and respiratory tract irritation. On the other hand, V compounds have been studied as anti-diabetic, as antihypertensive, as anorexigen and as anti-carcinogenic. V, which has remarkable biological effects should be studied in order to elucidate its biological mechanisms and to determine either its expositional risks or its pharmacological properties for human benefit.

  4. An investigation of the role of components in V/Ti/O-based catalysts for the gas-phase oxidation of o-xylene to phthalic anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Cavani, F.; Cortelli, C.; Frattini, A.; Luciani, S.; Panzacchi, B.; Trifiro, F. [Dipartimento di Chimica Industriale e dei Materiali, INSTM, Research Unit of Bologna (Italy); Fumagalli, C.; Leanza, R.; Mazzoni, G. [Lonza SpA, Scanzorosciate (B.G.) (Italy)

    2005-07-01

    In the present work the role of the different vanadium species which develop on titania-supported vanadium oxide, catalyst for the oxidation of o-xylene to phthalic anhydride, is investigated. Two different V/Ti/O series of catalysts were prepared, the first one consisting of samples having only different vanadium oxide content, and the second one of samples having 7 wt.% V{sub 2}O{sub 5} and variable amounts of Sb and Cs as promoters. By TPO (Thermal-Programmed-Oxidation) it was possible to quantify the different V species present on titania support, i.e., isolated vanadium, and dispersed polyvanadates plus bulk vanadia. The former species is the predominant one in samples having low vanadium oxide loading ({<=}2 wt.% V{sub 2}O{sub 5}, with TiO{sub 2} surface area 22.5 m{sup 2}/g), and possessed the highest intrinsic activity in o-xylene conversion. The presence of Sb, promoter of activity for V/Ti/O catalysts, increased the dispersion of the most active species. This promoting effect was more pronounced when both Cs and Sb were added as dopants to V/Ti/O. (orig.)

  5. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, Bartley B. [Univ. of California, Berkeley, CA (United States)

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF2, ThO2, YDT(0.85ThO2-0.15YO1.5), and LDT(0.85ThO2- 0.15LaO1.5) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  6. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, B.B.

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF[sub 2], ThO[sub 2], YDT(0.85ThO[sub 2]-0.15YO[sub 1.5]), and LDT(0.85ThO[sub 2]- 0.15LaO[sub 1.5]) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  7. Speciation and distribution of vanadium in drinking water iron pipe corrosion by-products.

    Science.gov (United States)

    Gerke, Tammie L; Scheckel, Kirk G; Maynard, J Barry

    2010-11-01

    Vanadium (V) when ingested from drinking water in high concentrations (>15 μg L(-1)) is a potential health risk and is on track to becoming a regulated contaminant. High concentrations of V have been documented in lead corrosion by-products as Pb(5)(V(5+)O(4))(3)Cl (vanadinite) which, in natural deposits is associated with iron oxides/oxyhydroxides, phases common in iron pipe corrosion by-products. The extent of potential reservoirs of V in iron corrosion by-products, its speciation, and mechanism of inclusion however are unknown. The aim of this study is to assess these parameters in iron corrosion by-products, implementing synchrotron-based μ-XRF mapping and μ-XANES along with traditional physiochemical characterization. The morphologies, mineralogies, and chemistry of the samples studied are superficially similar to typical iron corrosion by-products. However, we found V present as discrete grains of Pb(5)(V(5+)O(4))(3)Cl likely embedded in the surface regions of the iron corrosion by-products. Concentrations of V observed in bulk XRF analysis ranged from 35 to 899 mg kg(-1). We calculate that even in pipes with iron corrosion by-products with low V concentration, 100 mg kg(-1), as little as 0.0027% of a 0.1-cm thick X 100-cm long section of that corrosion by-product needs to be disturbed to increase V concentrations in the drinking water at the tap to levels well above the 15 μg L(-1) notification level set by the State of California and could adversely impact human health. In addition, it is likely that large reservoirs of V are associated with iron corrosion by-products in unlined cast iron mains and service branches in numerous drinking water distribution systems. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Different effects of vanadium ions on some DNA-metabolizing enzymes. [Calves, Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Sabbioni, E.; Clerici, L.; Brazzelli, A.

    The effects of vanadium on some enzymes involved in DNA metabolism were investigated in vitro. Vanadate (V) ions competitively inhibit calf thymus terminal deoxynucleotidyl transferase with K/sub i/ = 2.5 ..mu..M. A binding of vanadium to the enzyme with no change of the amount of the Zn constituent of the protein was found at concentrations of vanadate causing inhibition. The catalytic activity of mammalian DNA polymerase ..cap alpha.. was also inhibited by vanadate ions at an I/sub 50/ of 60 ..mu..M, while the bacterial (E. coli) DNA polymerase 1 was affected to the same extent only when the concentration of vanadate was raised to about 0.5 mM. In contrast to the inhibitory effects caused by vanadium on the nucleotidyl transferases, concentrations of pentavalent vanadium ions of the order of 10 ..mu..M increase 2.4-fold the hydrolytic activity of deoxyribonuclease I from bovine pancreas. These findings suggest that vanadium can interact with enzymes involved in nucleic acid metabolism.

  9. Determination of vanadium accumulation in onion root cells (Allium cepa L.) and its correlation with toxicity.

    Science.gov (United States)

    Marcano, Letty; Carruyo, Ingrid; Fernández, Yusmary; Montiel, Xiomara; Torrealba, Zaida

    2006-08-01

    The vanadium is a metal that presents great interest from the toxicological point of view, because of the numerous alterations that can take place in different biological systems. This work evaluated the capacity of vanadium accumulation and its correlation with genotoxic effects in root cells of Allium cepa L. The bulbs were cultivated in renovated filtered water each 24 h, at a temperature of 25 +/- 0.5 degrees C, in darkness and constant aeration. Treatments were carried out under the same experimental conditions, using water solutions of vanadium of 25, 50, 75 and 100 microg/g for 0, 12, 24, 48 and 72 h. A control was carried out where metal solution was substituted by distilled water. After the treatment, the meristems were fixed with alcohol--acetic acid (3:1) and stained according to the technique of Feulgen. The capacity of accumulation was determined by GFAAS. The analysis of the results revealed an accumulation of the metal for all times and concentrations. No correlation was presented among vanadium accumulation, growth and mitotic index; however, positive correlation was given with the induction of chromosomic aberrations. In conclusion, vanadium is able to induce cytotoxic effect in the exposed roots, but only genotoxic effect was correlated with metal accumulation.

  10. Facile Synthesis of Vanadium-Pentoxide Nanoparticles and Study on Their Electrochemical, Photocatalytic Properties.

    Science.gov (United States)

    Raj, Arguine Tes; Ramanujan, Kannan; Thangavel, Sakthivel; Gopalakrishan, Srikesh; Raghavan, Nivea; Venugopal, Gunasekaran

    2015-05-01

    Vanadium pentoxide (V2O5) nanoparticles were synthesized via an anionic, cationic and non-ionic surfactant-assisted hydrothermal method. The synthesized nanoparticles were characterized by using powder X-ray diffractometer, Scanning Electron Microscope, High Resolution Transmission Electron Microscope and UV-Vis spectroscopy. The experimental results confirm the formation of vanadium pentoxide nanoparticles. Vanadium pentoxide crystalline nanoparticles were prepared from various surfactants named Sodium Dodecyl Sulphate (SDS), Cetyl Trimethyl Ammonium Bromide (CTAB) and Triton-X, resulting the crystallite size of 61.6 nm, 27.5 nm and 46 nm respectively. From the electrochemical studies, it is found that vanadium pentoxide prepared with CTAB exhibit good cycle stability when compared with other two samples. Also the ionic-conducting behavior of the materials was investigated by using impedance analysis. In addition, the photocatalytic studies were performed and found better photocatalytic efficiency in V2O5 prepared with SDS, obtained through the degradation of MO dye under UV light irradiation. Our results show that Vanadium pentoxide can be a suitable candidate for photocatalytic application and as electrode in development of futuristic supercapacitors. Also this can be employed in various environmental eco-friendly applications.

  11. Effect of organic additives on positive electrolyte for vanadium redox battery

    Energy Technology Data Exchange (ETDEWEB)

    Li Sha [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Huang Kelong, E-mail: lisha_csu@163.com [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Liu Suqin; Fang Dong; Wu Xiongwei; Lu Dan; Wu Tao [Department of Functional Materials and Chemistry, School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2011-06-30

    Highlights: > Four organics as electrolyte additives of vanadium redox battery. > Changes are examined in the electrochemical properties of vanadium redox battery. > D-sorbitol is a suitable additive to the electrolyte for the vanadium redox battery. > The mechanism of improvement is discussed in detail. - Abstract: Fructose, mannitol, glucose, D-sorbitol are explored as additives in electrolyte for vanadium redox battery (VRB), respectively. The effects of additives on electrolyte are studied by cyclic voltammetry (CV), charge-discharge technique, electrochemical impedance spectroscopy (EIS) and Raman spectroscopy. The results indicate that the vanadium redox cell using the electrolyte with the additive of D-sorbitol exhibits the best electrochemical performance (the energy efficiency 81.8%). The EIS results indicate that the electrochemical activity of the electrolyte is improved by adding D-sorbitol, which can be interpreted as the increase of available (-OH) groups providing active sites for electron transfer. The Raman spectra show that VO{sup 2+} ions take part in forming a complex with the D-sorbitol, which not only improve solubility of V(V) electrolyte, but also provide more activity sites for the V(IV)/V(V) redox reaction.

  12. Selective speciation improves efficacy and lowers toxicity of platinum anticancer and vanadium antidiabetic drugs.

    Science.gov (United States)

    Doucette, Kaitlin A; Hassell, Kelly N; Crans, Debbie C

    2016-12-01

    Improving efficacy and lowering resistance to metal-based drugs can be addressed by consideration of the coordination complex speciation and key reactions important to vanadium antidiabetic drugs or platinum anticancer drugs under biological conditions. The methods of analyses vary depending on the specific metal ion chemistry. The vanadium compounds interconvert readily, whereas the reactions of the platinum compounds are much slower and thus much easier to study. However, the vanadium species are readily differentiated due to vanadium complexes differing in color. For both vanadium and platinum systems, understanding the processes as the compounds, Lipoplatin and Satraplatin, enter cells is needed to better combat the disease; there are many cellular metabolites, which may affect processing and thus the efficacy of the drugs. Examples of two formulations of platinum compounds illustrate how changing the chemistry of the platinum will result in less toxic and better tolerated drugs. The consequence of the much lower toxicity of the drug, can be readily realized because cisplatin administration requires hospital stay whereas Lipoplatin can be done in an outpatient manner. Similarly, the properties of Satraplatin allow for development of an oral drug. These forms of platinum demonstrate that the direct consequence of more selective speciation is lower side effects and cheaper administration of the anticancer agent. Therefore we urge that as the community goes forward in development of new drugs, control of speciation chemistry will be considered as one of the key strategies in the future development of anticancer drugs. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Radical reactions of diamine bis(phenolate) vanadium(iii) complexes. Solid state binding of O2 to form a vanadium(v) peroxo complex.

    Science.gov (United States)

    Barroso, Sónia; Coelho, Ana M; Adão, Pedro; Calhorda, Maria José; Martins, Ana M

    2017-07-25

    [VCl3(THF)3] reacted with the sodium salt of a tripodal diamine bisphenolate ligand precursor Na2L2 to give a paramagnetic d2 complex [V(L2)Cl] (2). The reaction of 2 with oxygen is strongly dependent on the experimental conditions, affording [VO(L2)Cl] (6) or [V(η2-O2)(L2)Cl] (7). The formation of 7 involves the direct addition of O2 to V(iii) in the solid state with oxidation to V(v) without significantly disturbing the structure of 2. DFT calculations showed that compound 7 is an intermediate in the formation of 6 from 2. The reaction involves the cleavage of the η1-O-O bond in a proposed dimeric species. The overall reaction of 2 moles of vanadium(iii), complex 2, and one mole of O2 to yield two moles of product 6 is a favourable process with ΔG298 = -38.3 kcal mol-1. 7 is the first non-oxido peroxidovanadium(v) complex obtained directly from the reaction of a crystal and the second example of a structurally characterized complex of that type. Reactions of V(L1)Cl (1) and V(L2)Cl (2) with one equivalent of the nitroxyl radical TEMPO in toluene also result in the formation of oxido V(v) complexes, VO(L1)Cl (5) and VO(L2)Cl (6). The reaction of VO(OiPr)3 with Na2L2 afforded [VO(L2)(OiPr)] (8) in high yield. A major isomer having the V[double bond, length as m-dash]O moiety in the equatorial plane was characterised by X-ray diffraction although solution NMR data showed the presence of a minor species with the oxido ligand trans to the tripodal nitrogen, as in 6. Complexes 6 and 8 are very active and selective sulfoxidation catalysts of thioanisole, but no enantiomeric excess was obtained.

  14. Vanadium supersaturated silicon system: a theoretical and experimental approach

    Science.gov (United States)

    Garcia-Hemme, Eric; García, Gregorio; Palacios, Pablo; Montero, Daniel; García-Hernansanz, Rodrigo; Gonzalez-Diaz, Germán; Wahnon, Perla

    2017-12-01

    The effect of high dose vanadium ion implantation and pulsed laser annealing on the crystal structure and sub-bandgap optical absorption features of V-supersaturated silicon samples has been studied through the combination of experimental and theoretical approaches. Interest in V-supersaturated Si focusses on its potential as a material having a new band within the Si bandgap. Rutherford backscattering spectrometry measurements and formation energies computed through quantum calculations provide evidence that V atoms are mainly located at interstitial positions. The response of sub-bandgap spectral photoconductance is extended far into the infrared region of the spectrum. Theoretical simulations (based on density functional theory and many-body perturbation in GW approximation) bring to light that, in addition to V atoms at interstitial positions, Si defects should also be taken into account in explaining the experimental profile of the spectral photoconductance. The combination of experimental and theoretical methods provides evidence that the improved spectral photoconductance up to 6.2 µm (0.2 eV) is due to new sub-bandgap transitions, for which the new band due to V atoms within the Si bandgap plays an essential role. This enables the use of V-supersaturated silicon in the third generation of photovoltaic devices.

  15. Vanadium haloperoxidase-catalyzed bromination and cyclization of terpenes.

    Science.gov (United States)

    Carter-Franklin, Jayme N; Parrish, Jon D; Tschirret-Guth, Richard A; Little, R Daniel; Butler, Alison

    2003-04-02

    Marine red algae (Rhodophyta) are a rich source of bioactive halogenated natural products, including cyclic terpenes. The biogenesis of certain cyclic halogenated marine natural products is thought to involve marine haloperoxidase enzymes. Evidence is presented that vanadium bromoperoxidase (V-BrPO) isolated and cloned from marine red algae that produce halogenated compounds (e.g., Plocamium cartilagineum, Laurencia pacifica, Corallina officinalis) can catalyze the bromination and cyclization of terpenes and terpene analogues. The V-BrPO-catalyzed reaction with the monoterpene nerol in the presence of bromide ion and hydrogen peroxide produces a monobromo eight-membered cyclic ether similar to laurencin, a brominated C15 acetogenin, from Laurencia glandulifera, along with noncyclic bromohydrin, epoxide, and dibromoproducts; however, reaction of aqueous bromine with nerol produced only noncyclic bromohydrin, epoxide, and dibromoproducts. The V-BrPO-catalyzed reaction with geraniol in the presence of bromide ion and hydrogen peroxide produces two singly brominated six-membered cyclic products, analogous to the ring structures of alpha and beta snyderols, brominated sesquiterpenes from Laurencia, spp., along with noncyclic bromohydrin, epoxide, and dibromoproducts; again, reaction of geraniol with aqueous bromine produces only noncyclic bromohydrin, epoxide, and dibromoproducts. Thus, V-BrPO can direct the electrophilic bromination and cyclization of terpenes.

  16. Development of high purity vanadium alloys for fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Muroga, Takeo [National Inst. for Fusion Sience, Toki, Gifu (Japan)

    2002-07-01

    Vanadium alloys are most attractive candidate materials for liquid Li self-cooled blanket system of fusion reactors. This paper summarizes the program and its activities of the NIFS (National Institute for Fusion Science), Japan for developments of high purity V-4Cr-4Ti alloys. The results from NIFS-Heats show various benefits by reducing the level of oxygen. Significant improvement of the impact properties of the welded joint by reducing oxygen level is one of examples in recent studies. Collaboration is in progress, in which those heats are being characterized by a number of research groups including Japanese universities, and international collaboration partners in the US, Russia and China. The impact tests of irradiated speciments are in progress for further investigation. Significant progress has been made recently on the insulator ceramic coating in static conditions in the Japan-USA Cooperation Program. The understanding on the condition of in-situ CaO coating in liquid Li was enhanced. Based on these achievements, a flowing loop test is being planned to investigate the effects of temperature gradient and Li chemistry. (Y. Tanaka)

  17. Giant extrinsic negative thermal expansion in vanadium pentoxide nanocrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Bahgat, A.A. [Department of Physics, Faculty of Science, King Khaled University, P.O. Box 9004, Abha (Saudi Arabia); Department of Physics, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo (Egypt); Al-Hajry, A. [Department of Physics, Faculty of Science, King Khaled University, P.O. Box 9004, Abha (Saudi Arabia); El-Desoky, M.M. [Department of Physics, Faculty of Science, King Khaled University, P.O. Box 9004, Abha (Saudi Arabia); Department of Physics, Faculty of Education, Suez Canal University, Al-Arish (Egypt)

    2006-06-15

    Vanadium pentoxide gels, V{sub 2}O{sub 5}.1.6H{sub 2}O, give rise to xerogel layers that exhibit a preferred orientation. X-ray diffraction of this xerogel displays the 00l peaks typical of a turbostratic stacking of the V{sub 2}O{sub 5} ribbons along a direction parallel to the substrate. The distance along the c-axis is observed from the interlayer spacing to decrease continuously with increasing temperature up to 180 C, as observed by high-temperature X-ray diffraction. This contraction may be described by an extrinsic mechanism of negative thermal expansion (NTE). The coefficient of NTE as large as -1.5 x 10{sup -3} K{sup -1} was observed. Full recovery of the interlayer spacing is obtained after cooling the sample to room temperature in open air, where water molecules are reabsorbed, indicating that the process is reversible and the heating process can be repeated without losing NTE. The structure of the xerogel was explored further using differential scanning calorimetry as well as infrared spectroscopy. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Enhancing the Performance of Vanadium Redox Flow Batteries using Quinones

    Science.gov (United States)

    Mulcahy, James W., III

    The global dependence on fossil fuels continues to increase while the supply diminishes, causing the proliferation in demand for renewable energy sources. Intermittent renewable energy sources such as wind and solar, require electrochemical storage devices in order to transfer stored energy to the power grid at a constant output. Redox flow batteries (RFB) have been studied extensively due to improvements in scalability, cyclability and efficiency over conventional batteries. Vanadium redox flow batteries (VRFB) provide one of the most comprehensive solutions to energy storage in relation to other RFBs by alleviating the problem of cross-contamination. Quinones are a class of organic compounds that have been extensively used in chemistry, biochemistry and pharmacology due to their catalytic properties, fast proton-coupled electron transfer, good chemical stability and low cost. Anthraquinones are a subcategory of quinones and have been utilized in several battery systems. Anthraquinone-2, 6-disulfonic acid (AQDS) was added to a VRFB in order to study its effects on cyclical performance. This study utilized carbon paper electrodes and a Nafion 117 ion exchange membrane for the membrane-electrode assembly (MEA). The cycling performance was investigated over multiple charge and discharge cycles and the addition of AQDS was found to increase capacity efficiency by an average of 7.6% over the standard VRFB, while decreasing the overall cycle duration by approximately 18%. It is thus reported that the addition of AQDS to a VRFB electrolyte has the potential to increase the activity and capacity with minimal increases in costs.

  19. Polymerization of Ethylene Catalyzed by Vanadium(III Complexes

    Directory of Open Access Journals (Sweden)

    Hamdi Ali Elagab

    2017-07-01

    Full Text Available Thirty five  complexes of 1,2- bis(benzimidazole, benzothiazole and benzoxazolebenzene,  1,2-bis(benzimidazole, benzothiazole and benzoxazole-4-methyl-benzene, 1,2-bis  (benzimidazole, benzothiazole and benzoxazole4-bromobenzene, 1, 2-bis(benzimidazole, benzothiazole and benzoxazole 4- chlorobenzene,  and 2, 6-bis(benzimidazole, benzothiazole and benzoxazole pyridine compounds with V (III metal centers were synthesized, characterized, activated with methylalumoxane (MAO and then tested for catalytic ethylene polymerization. The catalysts generally show moderate to good activities compared to the benchmark catalyst Cp2ZrCl2. The activities of the various catalysts were found to be function of the hetero atoms in the ligand frameworks and also strongly influenced by the bridging unit of the ligand. The highest activity was obtained with 36 / MAO (442 kg PE / mol cat. h. The produced polyethylenes showed high molecular weights (up to 2.7 × 106 g/mol and broad molecular weight distributions (PD = 1.4 - 16.6. Thermal analysis of polyethylenes produced with vanadium complexes revealed that the catalyst systems were capable to produce high density polyethylenes with melting temperatures > 135 °C and crystallization temperatures range from 117-120 °C with high degree of crystallinity. DOI: http://dx.doi.org/10.17807/orbital.v9i3.985 

  20. Tension-Enhanced Hydrogen Evolution Reaction on Vanadium Disulfide Monolayer

    Science.gov (United States)

    Pan, Hui

    2016-02-01

    Water electrolysis is an efficient way for hydrogen production. Finding efficient, cheap, and eco-friendly electrocatalysts is essential to the development of this technology. In the work, we present a first-principles study on the effects of tension on the hydrogen evolution reaction of a novel electrocatalyst, vanadium disulfide (VS2) monolayer. Two electrocatalytic processes, individual and collective processes, are investigated. We show that the catalytic ability of VS2 monolayer at higher hydrogen coverage can be efficiently improved by escalating tension. We find that the individual process is easier to occur in a wide range of hydrogen coverage and the collective process is possible at a certain hydrogen coverage under the same tension. The best hydrogen evolution reaction with near-zero Gibbs free energy can be achieved by tuning tension. We further show that the change of catalytic activity with tension and hydrogen coverage is induced by the change of free carrier density around the Fermi level, that is, higher carrier density, better catalytic performance. It is expected that tension can be a simple way to improve the catalytic activity, leading to the design of novel electrocatalysts for efficient hydrogen production from water electrolysis.