WorldWideScience

Sample records for borohydrides

  1. Manganese borohydride; synthesis and characterization

    OpenAIRE

    Richter, Bo; Ravnsbæk, Dorthe B.; Tumanov, Nikolay; Filinchuk, Yaroslav; Jensen, Torben R.

    2015-01-01

    Solvent-based synthesis and characterization of α-Mn(BH4)2 and a new nanoporous polymorph of manganese borohydride, γ-Mn(BH4)2, via a new solvate precursor, Mn(BH4)2·1/2S(CH3)2, is presented. Manganese chloride is reacted with lithium borohydride in a toluene/dimethylsulfide mixture at room temperature, which yields halide and solvent-free manganese borohydride after extraction with dimethylsulfide (DMS) and subsequent removal of residual solvent. This work constitutes the first example of es...

  2. Catalyzed borohydrides for hydrogen storage

    Science.gov (United States)

    Au, Ming

    2012-02-28

    A hydrogen storage material and process is provided in which alkali borohydride materials are created which contain effective amounts of catalyst(s) which include transition metal oxides, halides, and chlorides of titanium, zirconium, tin, and combinations of the various catalysts. When the catalysts are added to an alkali borodydride such as a lithium borohydride, the initial hydrogen release point of the resulting mixture is substantially lowered. Additionally, the hydrogen storage material may be rehydrided with weight percent values of hydrogen at least about 9 percent.

  3. Modeling of synthesis of borohydride lanthanides with auto initiations

    International Nuclear Information System (INIS)

    The mechanism of process of synthesis of lanthanide borohydrides interaction of lanthanide chlorides with sodium borohydride was investigated. The formation of dual-lanthanide complex with sodium borohydride was considered. The oscillatory nature of synthesis and initiation role of the lanthanide borohydride was shown. Polynomial for programmed synthesis of lanthanide borohydrides was composed.

  4. Ballmilling of metal borohydrides for hydrogen storage

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    ’s dehydrogenated state. Specifically, the research undertaken targets CaB6 whose boron is in a octahedral network, or AlB2 whose boron is layered. These compounds were then reactive ball milled with alkali and alkaline earth metal under hydrogen pressure, with the intention of forming metal borohydrides. For CaB6...... investigation is to hydrogenate simple compounds such as metalborides and hydrides with the intention of forming a new and more hydrogen rich borohydride. In contrast to mainstream research, the method of synthesis has been based on reactants that are expected to be found in the metal borohydride...

  5. Chloride substitution in sodium borohydride

    Science.gov (United States)

    Ravnsbæk, Dorthe B.; Rude, Line H.; Jensen, Torben R.

    2011-07-01

    The dissolution of sodium chloride and sodium borohydride into each other resulting in formation of solid solutions of composition Na(BH 4) 1- xCl x is studied. The dissolution reaction is facilitated by two methods: ball milling or combination of ball milling and annealing at 300 °C for three days of NaBH 4-NaCl samples in molar ratios of 0.5:0.5 and 0.75:0.25. The degree of dissolution is studied by Rietveld refinement of synchrotron radiation powder X-ray diffraction (SR-PXD) data. The results show that dissolution of 10 mol% NaCl into NaBH 4, forming Na(BH 4) 0.9Cl 0.1, takes place during ball milling. A higher degree of dissolution of NaCl in NaBH 4 is obtained by annealing resulting in solid solutions containing up to 57 mol% NaCl, i.e. Na(BH 4) 0.43Cl 0.57. In addition, annealing results in dissolution of 10-20 mol% NaBH 4 into NaCl. The mechanism of the dissolution during annealing and the decomposition pathway of the solid solutions are studied by in situ SR-PXD. Furthermore, the stability upon hydrogen release and uptake were studied by Sieverts measurements.

  6. Synthesis and thermal stability of tetrahydrofuranate of magnesium borohydride

    International Nuclear Information System (INIS)

    Present article is devoted to synthesis and thermal stability of tetrahydrofuranate of magnesium borohydride. The thermal stability of tetrahydrofuranate of magnesium borohydride was studied. The character of thermal process passing was defined. The possibility of de solvation of initial sample was considered. The possibility of obtaining of not solvated magnesium borohydride was considered as well.

  7. Chitosan-supported Borohydride Reducing Agent

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new chitosan-supported borohydride reducing reagent (CBER) was prepared by treatment of KBH4 with the resin of chitosan derivative, which was first synthesized fiom the reaction of cross-linked chitosan microsphere with glycidyl trimethylammonium chloride. CBER could reduce aromatic carbonyl compound to corresponding alcohol.

  8. BIMETALLIC LITHIUM BOROHYDRIDES TOWARD REVERSIBLE HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Au, M.

    2010-10-21

    Borohydrides such as LiBH{sub 4} have been studied as candidates for hydrogen storage because of their high hydrogen contents (18.4 wt% for LiBH{sub 4}). Limited success has been made in reducing the dehydrogenation temperature by adding reactants such as metals, metal oxides and metal halides. However, full rehydrogenation has not been realized because of multi-step decomposition processes and the stable intermediate species produced. It is suggested that adding second cation in LiBH{sub 4} may reduce the binding energy of B-H. The second cation may also provide the pathway for full rehydrogenation. In this work, several bimetallic borohydrides were synthesized using wet chemistry, high pressure reactive ball milling and sintering processes. The investigation found that the thermodynamic stability was reduced, but the full rehydrogenation is still a challenge. Although our experiments show the partial reversibility of the bimetallic borohydrides, it was not sustainable during dehydriding-rehydriding cycles because of the accumulation of hydrogen inert species.

  9. Catalytic polymeric electrodes for direct borohydride fuel cells

    Science.gov (United States)

    Bayatsarmadi, Bita; Peters, Alice; Talemi, Pejman

    2016-08-01

    The direct borohydride fuel cell (DBFC) is a new class of fuel cells that produces non-toxic by-products and has a potential for a high voltage and high energy density. A major challenge in developing efficient DBFCs is the development of an efficient, stable, and economic catalyst for the oxidation of borohydride. In this paper, we report the use of conducting polymer Poly(3,4-ethylenedioxythiophene) (PEDOT) as electrocatalysts in DBFC. PEDOT electrodes prepared by vacuum phase polymerization exhibited electrocatalytic behavior towards oxidation of borohydride and reduction of hydrogen peroxide. Spectroscopic analysis of samples showed that PEDOT can act as an interface for electron transfer from borohydride ions. Comparing the polarization curves of DBFCs with PEDOT coated on graphite electrodes and cells with bare graphite electrodes, demonstrated higher voltage, maximum power density, and stability.

  10. Borohydride electro-oxidation on Pt single crystal electrodes

    OpenAIRE

    Briega-Martos, Valentín; Herrero, Enrique; Juan M Feliu

    2015-01-01

    The borohydride oxidation reaction on platinum single-crystal electrodes has been studied in sodium hydroxide solution using static and rotating conditions. The results show that borohydride electro-oxidation is a structure sensitive process on Pt surfaces. Significant changes in the measured currents are observed at low potentials. In this region, the Pt(111) electrode exhibits the lowest activity, whereas the highest currents are measured for the Pt(110) electrode. The behavior of the diffe...

  11. Oscillatory instabilities in the electrooxidation of borohydride on platinum

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Eduardo G.; Varela, Hamilton, E-mail: varela@iqsc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica

    2014-03-15

    The borohydride ion has been pointed as a promising alternative fuel. Most of the investigation on its electrochemistry is devoted to the electrocatalytic aspects of its electrooxidation on platinum and gold surfaces. Besides the known kinetic limitations and intricate mechanism, our Group has recently found the occurrence of two regions of bi-stability and autocatalysis in the electrode potential during the open circuit interaction of borohydride and oxidized platinum surfaces. Following this previous contribution, the occurrence of more complicated phenomena is here presented: namely the presence of electrochemical oscillations during the electrooxidation of borohydride on platinum in alkaline media. Current oscillations were found to be associated to two distinct instability windows and characterized in the resistance-potential parameter plane. The dynamic features of such oscillations suggest the existence of distinct mechanisms according to the potential region. Previously published results obtained under non-oscillatory regime were used to give some hints on the surface chemistry behind the observed dynamics. (author)

  12. Methods to Stabilize and Destabilize Ammonium Borohydride

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Thomas K.; Karkamkar, Abhijeet J.; Bowden, Mark E.; Besenbacher, Fleming; Jensen, Torben R.; Autrey, Thomas

    2013-01-21

    Ammonium borohydride, NH4BH4, has a high hydrogen content of ρm = 24.5 wt% H2 and releases 18 wt% H2 below T = 160 °C. However, the half-life of bulk NH4BH4 at ambient temperatures, ~6 h, is insufficient for practical applications. The decomposition of NH4BH4 (ABH2) was studied at variable hydrogen and argon back pressures to investigate possible pressure mediated stabilization effects. The hydrogen release rate from solid ABH2 at ambient temperatures is reduced by ~16 % upon increasing the hydrogen back pressure from 5 to 54 bar. Similar results were obtained using argon pressure and the observed stabilization may be explained by a positive volume of activation in the transition state leading to hydrogen release. Nanoconfinement in mesoporous silica, MCM-41, was investigated as alternative means to stabilize NH4BH4. However, other factors appear to significantly destabilize NH4BH4 and it rapidly decomposes at ambient temperatures into [(NH3)2BH2][BH4] (DADB) in accordance with the bulk reaction scheme. The hydrogen desorption kinetics from nanoconfined [(NH3)2BH2][BH4] is moderately enhanced as evidenced by a reduction in the DSC decomposition peak temperature of ΔT = -13 °C as compared to the bulk material. Finally, we note a surprising result, storage of DADB at temperature < -30 °C transformed, reversibly, the [(NH3)2BH2][BH4] into a new low temperature polymorph as revealed by both XRD and solid state MAS 11B MAS NMR. TA & AK are thankful for support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle.

  13. Barium borohydride chlorides: synthesis, crystal structures and thermal properties.

    Science.gov (United States)

    Grube, Elisabeth; Olesen, Cathrine H; Ravnsbæk, Dorthe B; Jensen, Torben R

    2016-05-10

    Here we report the synthesis, mechanism of formation, characterization and thermal decomposition of new barium borohydride chlorides prepared by mechanochemistry and thermal treatment of MBH4-BaCl2, M = Li, Na or K in ratios 1 : 1 and 1 : 2. Initially, orthorhombic barium chloride, o-BaCl2 transforms into o-Ba(BH4)xCl2-x, x ∼ 0.15. Excess LiBH4 leads to continued anion substitution and a phase transformation into hexagonal barium borohydride chloride h-Ba(BH4)xCl2-x, which accommodates higher amounts of borohydride, possibly x ∼ 0.85 and resembles h-BaCl2. Thus, two solid solutions are in equilibrium during mechano-chemical treatment of LiBH4-BaCl2 (1 : 1) whereas LiBH4-BaCl2 (2 : 1) converts to h-Ba(BH4)0.85Cl1.15. Upon thermal treatment at T > ∼200 °C, h-Ba(BH4)0.85Cl1.15 transforms into another orthorhombic barium borohydride chloride compound, o-Ba(BH4)0.85Cl1.15, which is structurally similar to o-BaBr2. The samples with M = Na and K have lower reactivity and form o-Ba(BH4)xCl2-x, x ∼ 0.1 and a solid solution of sodium chloride dissolved in solid sodium borohydride, Na(BH4)1-xClx, x = 0.07. The new compounds and reaction mechanisms are investigated by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), Fourier transform infrared spectroscopy (FT-IR) and simultaneous thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mass spectroscopy (MS) and temperature programmed photographic analysis (TPPA). PMID:27109871

  14. New Transition metal assisted complex borohydrides for hydrogen storage

    International Nuclear Information System (INIS)

    High capacity hydrogen storage systems are indeed essential for the on-board vehicular application that leads to the pollution free environment. Apart from the various hydrogen storage systems explored in the past, complex hydrides involving light weight alkali/alkaline metals exhibits promising hydrogenation/ dehydrogenation characteristics. New transition metal assisted complex borohydrides [Zn(BH4)2] have been successfully synthesized by an inexpensive mechano-chemical process. These complex hydrides possesses gravimetric hydrogen storage capacity of ∼8.4 wt.% at around 120 C. We have determined the volumetric hydrogen absorption and desorption of these materials for a number of cycles. Another complex borohydride mixture LiBH4/MgH2 catalyzed with ZnCl2 has been synthesized and characterized using various analytical techniques. (authors)

  15. Method for labeling technetium or rhenium using borohydride exchange resin

    International Nuclear Information System (INIS)

    We have established a new method for labelling a disulfide with technetium or rhenium. This method consists of the reduction of both pertechnetate or perrhenate and the disulfide in the presence of borohydride exchange resin resulting in a complex of technetium or rhenium with thiol. This method makes it possible to skip the synthetic step of thiol-protected S-precursor and it can be applied to the production of high value-added radiophamaceuticals

  16. Metal Borohydrides synthesized from metal borides and metal hydrides

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    and Ca(BH4)2, respectively [3,4]. An attempt to synthesize alkali and alkaline earth metal borohydrides from various borides by ball milling under high hydrogen pressure is presented here. MgB2, AlB2 and CaB6 have been milled with MHx (M = Li, Na, Mg, Ca) at p(H2) = 110 bar for 24 hours. All samples......Metal Borohydrides Synthesized from Metal Borides and Metal Hydrides Alexander Fogha, Sanna Sommera, Kasper T. Møllera, T. R. Jensena aCenter for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO) and Chemistry Department, Aarhus University, Langelandsgade 140, DK-8000...... Aarhus C, Denmark email: gallafogh@hotmail.com / sanna-sommer@hotmail.com Magnesium boride, MgB2, ball milled with MH (M = Li, Na, Ca) followed by hydrogenation under high hydrogen pressure, readily forms the corresponding metal borohydrides, M(BH4)x (M = Li, Na, Ca) and MgH2 according to reaction scheme...

  17. A composite of borohydride and super absorbent polymer for hydrogen generation

    Science.gov (United States)

    Li, Z. P.; Liu, B. H.; Liu, F. F.; Xu, D.

    To develop a hydrogen source for underwater applications, a composite of sodium borohydride and super absorbent polymer (SAP) is prepared by ball milling sodium borohydride powder with SAP powder, and by dehydrating an alkaline borohydride gel. When sodium polyacrylate (NaPAA) is used as the SAP, the resulting composite exhibits a high rate of borohydride hydrolysis for hydrogen generation. A mechanism of hydrogen evolution from the NaBH 4-NaPAA composite is suggested based on structure analysis by X-ray diffraction and scanning electron microscopy. The effects of water and NiCl 2 content in the precursor solution on the hydrogen evolution behavior are investigated and discussed.

  18. Effect of sodium borohydride synthesis on NaBH4-H2 system economics

    International Nuclear Information System (INIS)

    The hazards and negative impacts of fossil fuel usage on environment and the prospect of fossil fuel depletion in near future have urged scientists to search for and use clean energy sources and alternative fuels. Hydrogen is the best fuel among others, which can minimize the effects of global warming. Although it is currently more expensive than other fuels, it will be cheaper following further developments in hydrogen technologies from production till end-use. Hydrogen storage is a critical issue in terms of safety and economics of hydrogen energy system. Chemical hydrides are an attractive hydrogen storage method due to their potential of achieving high volumetric and gravimetric storage densities. Among chemical hydrides, sodium borohydride (NaBH4) is given a big attention, due to its 10.8% theoretical hydrogen storage capacity. Hydrogen, which can be released by sodium borohydride hydrolysis reaction on-site, can be used in a proton exchange membrane fuel cell (PEMFC) at anode. on the other hand, sodium borohydride solution can be used directly in a borohydride fuel cell (DBFC) at anode. Like the other chemical hydrides, sodium borohydride has been an expensive material up to now, constituting a major obstacle to commercialization of sodium borohydride as a hydrogen storage method. This paper aims to give an approximate estimation process cost of the NaBH4-H2 system by taking into account both the energy and raw material costs, starting with sodium borohydride production till recycling of it. Two different methods to synthesize sodium borohydride are analyzed and their effects on total cost are compared. It was found that the usage of Bayer process to synthesize sodium borohydride makes the overall sodium borohydride - hydrogen system cost higher than the total cost of the alternative process which starts with the production of sodium borohydride from borax decahydrate. (authors)

  19. Borohydride electro-oxidation by Ag-doped lanthanum chromites

    Indian Academy of Sciences (India)

    S Suresh Balaji; A Usha; V V Giridhar

    2014-05-01

    The electrocatalytic activity of Ag-doped lanthanum chromites electrode materials viz., LaCr0.4Ag0.6O3 and LaCr0.7Ag0.3O3 prepared by decomposing the precursor complex is studied. Pure LaCrO3 is synthesized by combustion route using oxalic acid as a fuel. The decomposition behaviour of the assynthesized powder obtained in the latter method is characterized by TGA-DTA and XRD. Both the precursor complex and the as-synthesized powder are calcined at 900°C for 7 and 10 h, respectively. XRD of the final product after calcinations indicated the formation of perovskite phase with minor amounts of impurity phases of component oxides in the Ag-doped lanthanum chromites and pure perovskite phase in the undoped one. The surface morphology of the perovskites is studied by SEM. The electrocatalytic activity of the perovskite powders for borohydride oxidation is studied by using cyclic voltammetry (CV) at a catalyst loading of 0.7 mgcm−2 for both Ag-doped and undoped LaCrO3 coated on glassy carbon substrate. Calibration plots are obtained by plotting the anodic peak current versus concentration of borohydride in the range of 20-100 mM. The sensitivities of the three perovskites towards borohydride oxidation indicated that LaCr0.4Ag0.6O3 is the best among all the perovskites studied giving a value of 1.395 A/mM.

  20. Sodium borohydride reduction of aromatic carboxylic acids via methyl esters

    Indian Academy of Sciences (India)

    Aamer Saeed; Zaman Ashraf

    2006-09-01

    A number of important aromatic carboxylic acids precursors, or intermediates in the syntheses of natural products, are converted into methyl esters and reduced to the corresponding primary alcohols using a sodium borohydride-THF-methanol system. The alcohols are obtained in 70-92% yields in 2-5 hours, in a pure state. This two-step procedure not only provides a better alternative to aluminum hydride reduction of acids but also allows the selective reduction of esters in presence of acids, amides, nitriles or nitro functions which are not affected under these conditions.

  1. Separate Determination of Borohydride, Borate, Hydroxide, and Carbonate in the Borohydride Fuel Cell by Acid-Base and Iodometric Potentiometric Titration

    OpenAIRE

    Churikov, A. V.; S. L. Shmakov; Romanova, V. O.; Zapsis, K. V.; Ushakov, A. V.; Ivanishchev, A. V.; Churikov, M. A.

    2014-01-01

    A methodology for quantitative chemical analysis of the complex “borohydride-borate-hydroxide-carbonate-water” mixtures used as fuel in the borohydride fuel cell was developed and optimized. The methodology includes the combined usage of the acid-base and iodometric titration methods. The acid-base titration method, which simultaneously uses the technique of differentiation and computer simulation of titration curves, allows one to determine the contents of hydroxide (alkali), carbonate, and ...

  2. In situ infrared (FTIR) study of the borohydride oxidation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Concha, B. Molina; Chatenet, M. [Laboratoire d' Electrochimie et de Physico-chimie, des Materiaux et des Interfaces (LEPMI), UMR 5631 CNRS/Grenoble-INP/UJF, 1130 Rue de la Piscine, BP75, 38402 Saint Martin d' Heres Cedex (France); Coutanceau, C.; Hahn, F. [Laboratoire de Catalyse en Chimie Organique (LACCO), UMR 6503 CNRS, Universite de Poitiers, 40 Av. du, Recteur Pineau, 86000 Poitiers (France)

    2009-01-15

    The direct borohydride fuel cell (DBFC) is an interesting alternative for the electrochemical power generation at lower temperatures due to its high anode theoretical specific capacity (5 A h g{sup -1}). However, the borohydride oxidation reaction (BOR) is a very complex eight-electron reaction, influenced by the nature of the electrode material (catalytic or not with respect to BH{sub 4}{sup -} hydrolysis), the [BH{sub 4}{sup -}][OH{sup -}] ratio and the temperature. In order to understand the BOR mechanism, we performed in situ infrared reflectance spectroscopy measurements (SPAIRS technique) in 1 M NaOH/1 M NaBH{sub 4} with the aim to study intermediate reactions occurring on a gold electrode (a poor BH{sub 4}{sup -} hydrolysis catalyst). We monitored several bands in B-H (1184 cm{sup -1}) and B-O bond regions (1326 and 1415 cm{sup -1}), appearing sequentially with increasing electrode polarisation. Thanks to these experimental findings, we propose possible initial elementary steps for the BOR. (author)

  3. Life time test in direct borohydride fuel cell system

    Energy Technology Data Exchange (ETDEWEB)

    Jamard, Romain [Commissariat a l' Energie Atomique (CEA), LITEN-DTNM-LCH, 17 av. des martyrs, 38054 Grenoble Cedex 9 (France); Centre National de la Recherche Scientifique (CNRS), Laboratoire de Catalyse en Chimie Organique LACCO UMR6503, 40 av. du Recteur Pineau, 86022 Poitiers (France); Salomon, Jeremie; Martinent-Beaumont, Audrey [Commissariat a l' Energie Atomique (CEA), LITEN-DTNM-LCH, 17 av. des martyrs, 38054 Grenoble Cedex 9 (France); Coutanceau, Christophe [Centre National de la Recherche Scientifique (CNRS), Laboratoire de Catalyse en Chimie Organique LACCO UMR6503, 40 av. du Recteur Pineau, 86022 Poitiers (France)

    2009-09-05

    The electric performances of direct borohydride fuel cells (DBFCs) are evaluated in terms of power density and life time with respect to the NaBH{sub 4} concentration. A DBFC constituted of an anionic membrane, a 0.6 mg{sub Pt} cm{sup -2} anode and a commercial non-platinum based cathode led to performances as high as 200 mW cm{sup -2} at room temperature and with natural convection of air. Electrochemical life time test at 0.55 mA cm{sup -2} with a 5 M NaBH{sub 4}/1 M NaOH solution shows a voltage diminution of 1 mV h{sup -1} and a drastic drop of performances after 250 h. The life time is twice longer with 2 M NaBH{sub 4}/1 M NaOH solution (450 h) and the voltage decrease is 0.5 mV h{sup -1}. Analyses of the components after life time tests indicate that voltage loss is mainly due to the degradation of the cathode performance. Crystallisation of carbonate and borate is observed at the cathode side, although the anionic membrane displays low permeability to borohydride. (author)

  4. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    Science.gov (United States)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-08-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

  5. High electrocatalytic activity for borohydride oxidation on palladium nanocubes enclosed by {200} facets

    Science.gov (United States)

    Qin, Haiying; Chen, Kaijian; Zhu, Cai; Liu, Jiabin; Wang, Juan; He, Yan; Chi, Hongzhong; Ni, Hualiang; Ji, Zhenguo

    2015-12-01

    Pd nanocubes enclosed by {200} facets are synthesized and used as an anode catalyst in direct borohydride fuel cell (DBFC) to study the electrocatalytic activity of Pd towards borohydride oxidation reaction (BOR) by modifying its surface atomic structure. A 7e reaction towards BOR is implemented on Pd nanocubes with a borohydride concentration as high as 3.26 M. The cell using Pd nanocubes as anode catalyst exhibits an obvious higher power density than the cell using commercial Pd/C, and maintained 99% of its voltage after 50 h stability test. It suggests that the Pd nanocubes could be a promising anode catalyst for the DBFC application.

  6. Complex metal borohydrides: multifunctional materials for energy storage and conversion.

    Science.gov (United States)

    Mohtadi, Rana; Remhof, Arndt; Jena, Puru

    2016-09-01

    With the limited supply of fossil fuels and their adverse effect on the climate and the environment, it has become a global priority to seek alternate sources of energy that are clean, abundant, and sustainable. While sources such as solar, wind, and hydrogen can meet the world's energy demand, considerable challenges remain to find materials that can store and/or convert energy efficiently. This topical review focuses on one such class of materials, namely, multi-functional complex metal borohydrides that not only have the ability to store sufficient amount of hydrogen to meet the needs of the transportation industry, but also can be used for a new generation of metal ion batteries and solar cells. We discuss the material challenges in all these areas and review the progress that has been made to address them, the issues that still need to be resolved and the outlook for the future. PMID:27384871

  7. Recent progress in metal borohydrides for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.-W.; Yan, Y.; Orimo, S.-I. [Tohoku University, Institute for Materials Research (IMR), Sendai (Japan); Zuettel, A. [Department of the Environment, Energy and Mobility (EMPA), Abt. 138 ' Hydrogen and Energy' , Duebendorf (Switzerland); Jensen, C. M. [University of Hawaii, Department of Chemistry, Honolulu, HI (United States)

    2011-07-01

    The prerequisite for widespread use of hydrogen as an energy carrier is the development of new materials that can safely store it at high gravimetric and volumetric densities. Metal borohydrides M(BH{sub 4}){sub n} (n is the valence of metal M), in particular, have high hydrogen density, and are therefore regarded as one such potential hydrogen storage material. For fuel cell vehicles, the goal for on-board storage systems is to achieve reversible store at high density but moderate temperature and hydrogen pressure. To this end, a large amount of effort has been devoted to improvements in their thermodynamic and kinetic aspects. This review provides an overview of recent research activity on various M(BH{sub 4}){sub n}, with a focus on the fundamental dehydrogenation and rehydrogenation properties and on providing guidance for material design in terms of tailoring thermodynamics and promoting kinetics for hydrogen storage. (authors)

  8. Complex metal borohydrides: multifunctional materials for energy storage and conversion

    Science.gov (United States)

    Mohtadi, Rana; Remhof, Arndt; Jena, Puru

    2016-09-01

    With the limited supply of fossil fuels and their adverse effect on the climate and the environment, it has become a global priority to seek alternate sources of energy that are clean, abundant, and sustainable. While sources such as solar, wind, and hydrogen can meet the world’s energy demand, considerable challenges remain to find materials that can store and/or convert energy efficiently. This topical review focuses on one such class of materials, namely, multi-functional complex metal borohydrides that not only have the ability to store sufficient amount of hydrogen to meet the needs of the transportation industry, but also can be used for a new generation of metal ion batteries and solar cells. We discuss the material challenges in all these areas and review the progress that has been made to address them, the issues that still need to be resolved and the outlook for the future.

  9. Modified lithium borohydrides for reversible hydrogen storage (2).

    Science.gov (United States)

    Au, Ming; Jurgensen, Arthur; Zeigler, Kristine

    2006-12-28

    This paper reports the results of the effort to destabilize lithium borohydride for reversible hydrogen storage. Various metals, metal hydrides, and metal chlorides were selected and evaluated as destabilization agents for reducing dehydriding temperatures and improving dehydriding/rehydriding reversibility. The most effective material was LiBH4 + 0.2MgCl2 + 0.1TiCl3 which starts desorbing 5 wt % of hydrogen at 60 degrees C and can be rehydrogenated to 4.5 wt % at 600 degrees C and 70 bar. X-ray diffraction and Raman spectroscopic analysis show the interaction of LiBH4 with additives and the unusual change of B-H stretching. PMID:17181309

  10. Reduction of Aldehydes and Ketones with Potassium Borohydride as Reductant

    Institute of Scientific and Technical Information of China (English)

    罗慧谋; 李毅群

    2005-01-01

    A series of aldehydes and ketones were reduced by potassium borohydride in an ionic liquid/water ([bmim]PF6/H2O) biphasic system to afford corresponding alcohol with high purity in excellent yields. The ionic liquid/water biphasic system could promote the chemoselectivity and the substituents such as nitro group and chlorine remained intact. Aromatic ketones were not as active as aromatic aldhydes and cyclic ketones owing to their higher steric hindrance. The ionic liquid could be recycled and reused. This protocol has notable advantages of no need of phase transfer catalyst and organic solvents, mild conditions, simple operation, short reaction time, ease work-up, high yields and recycling of the ionic liquid.

  11. PALLADIUM COATED STEEL ELECTRODE - PREPARATION, CHARACTERIZATION AND THEIR USE OF BOROHYDRIDE DETERMINATION

    OpenAIRE

    Karaboduk, Kuddusi; Hasdemir, Erdoğan; Aksu, Mehmet Levent

    2015-01-01

    The purpose of this study is the fabrication of a cost effective palladium coated steel electrode (pd-S) for the direct analysis of the sodium borohydride (BH4-). The electrode was prepared by the cyclic voltammetry. The electrode was observed to have a high catalytic effect on the oxidation of BH4-. The Pd-S surface was characterized with profilometri, scanning electron microscope, ferrocene test and electrochemical impedance spectroscopic technique. The effects of  borohydride concentration...

  12. Bimetallic nanoparticles of copper and indium by borohydride reduction

    International Nuclear Information System (INIS)

    This study investigated the preparation of copper-indium bimetallic nanoparticles through the borohydride reduction in an alcohol solution for application in ink-coating and sputtering target materials. Copper, indium metal and copper-indium intermetallic materials were synthesized by reacting CuCl2 and InCl3 with NaBH4 in 2-propanol (IPA) and tetraethylene glycol (TEG) at room temperature. The Cu-In samples contained Cu2In and CuIn phases with particle sizes of 10-100 nm and 30-200 nm in both the IPA and TEG solutions, respectively. The nanoparticulate Cu-In precursor layer was coated onto a soda-lime glass through spin-casting, where the Cu-In intermetallic phases of Cu2In and Cu11In9 were produced through heat treatment in Ar gas and a microstructured CuInSe2 layer was produced in a selenium atmosphere. Cu, In, Cu-In intermetallic nanoparticles and the films were characterized using powder X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analyses.

  13. Sodium borohydride removes aldehyde inhibitors for enhancing biohydrogen fermentation.

    Science.gov (United States)

    Lin, Richen; Cheng, Jun; Ding, Lingkan; Song, Wenlu; Zhou, Junhu; Cen, Kefa

    2015-12-01

    To enhance biohydrogen production from glucose and xylose in the presence of aldehyde inhibitors, reducing agent (i.e., sodium borohydride) was in situ added for effective detoxification. The detoxification efficiencies of furfural (96.7%) and 5-hydroxymethylfurfural (5-HMF, 91.7%) with 30mM NaBH4 were much higher than those of vanillin (77.3%) and syringaldehyde (69.3%). Biohydrogen fermentation was completely inhibited without detoxification, probably because of the consumption of nicotinamide adenine dinucleotide (NADH) by inhibitors reduction (R-CHO+2NADH→R-CH2OH+2NAD(+)). Addition of 30mM NaBH4 provided the reducing power necessary for inhibitors reduction (4R-CHO+NaBH4+2H2O→4R-CH2OH+NaBO2). The recovered reducing power in fermentation resulted in 99.3% recovery of the hydrogen yield and 64.6% recovery of peak production rate. Metabolite production and carbon conversion after detoxification significantly increased to 63.7mM and 81.9%, respectively. PMID:26342346

  14. Hydrogen generation from hydrolysis of sodium borohydride using Ru(0) nanoclusters as catalyst

    International Nuclear Information System (INIS)

    Sodium borohydride is stable in aqueous alkaline solution, however, it hydrolyses in water to hydrogen gas in the presence of suitable catalyst. By this way hydrogen can be generated safely for the fuel cells. Generating H2 catalytically from NaBH4 solutions has many advantages: NaBH4 solutions are nonflammable, reaction products are environmentally benign, rate of H2 generation is easily controlled, the reaction product NaBO2 can be recycled, H2 can be generated even at low temperatures. All of the catalysts that has been used in hydrolysis of sodium borohydride are bulk metals and they act as heterogeneous catalysts. The limited surface area of the heterogeneous catalysts causes lower catalytic activity as the activity of catalyst is directly related to its surface area. Thus, the use of metal nanoparticles with large surface area provides potential route to increase the catalytic activity. Here, we report, for the first time, the use of ruthenium(0) nanoclusters as catalyst in the hydrolysis of sodium borohydride liberating hydrogen gas. The ruthenium nanoparticles are generated from the reduction of ruthenium(III) chloride by sodium borohydride in water and stabilized by specific ligand. The ruthenium(0) nanoclusters are found to be highly active catalyst for the hydrolysis of sodium borohydride

  15. Understanding oscillatory phenomena in molecular hydrogen generation via sodium borohydride hydrolysis.

    Science.gov (United States)

    Budroni, M A; Biosa, E; Garroni, S; Mulas, G R C; Marchettini, N; Culeddu, N; Rustici, M

    2013-11-14

    The hydrolysis of borohydride salts represents one of the most promising processes for the generation of high purity molecular hydrogen under mild conditions. In this work we show that the sodium borohydride hydrolysis exhibits a fingerprinting periodic oscillatory transient in the hydrogen flow over a wide range of experimental conditions. We disproved the possibility that flow oscillations are driven by supersaturation phenomena of gaseous bubbles in the reactive mixture or by a nonlinear thermal feedback according to a thermokinetic model. Our experimental results indicate that the NaBH4 hydrolysis is a spontaneous inorganic oscillator, in which the hydrogen flow oscillations are coupled to an "oscillophor" in the reactive solution. The discovery of this original oscillator paves the way for a new class of chemical oscillators, with fundamental implications not only for testing the general theory on oscillations, but also with a view to chemical control of borohydride systems used as a source of hydrogen based green fuel. PMID:24084866

  16. The Concept about the Regeneration of Spent Borohydrides and Used Catalysts from Green Electricity

    Directory of Open Access Journals (Sweden)

    Cheng-Hong Liu

    2015-06-01

    Full Text Available Currently, the Brown-Schlesinger process is still regarded as the most common and mature method for the commercial production of sodium borohydride (NaBH4. However, the metallic sodium, currently produced from the electrolysis of molten NaCl that is mass-produced by evaporation of seawater or brine, is probably the most costly raw material. Recently, several reports have demonstrated the feasibility of utilizing green electricity such as offshore wind power to produce metallic sodium through electrolysis of seawater. Based on this concept, we have made improvements and modified our previously proposed life cycle of sodium borohydride (NaBH4 and ammonia borane (NH3BH3, in order to further reduce costs in the conventional Brown-Schlesinger process. In summary, the revision in the concept combining the regeneration of the spent borohydrides and the used catalysts with the green electricity is reflected in (1 that metallic sodium could be produced from NaCl of high purity obtained from the conversion of the byproduct in the synthesis of NH3BH3 to devoid the complicated purification procedures if produced from seawater; and (2 that the recycling and the regeneration processes of the spent NaBH4 and NH3BH3 as well as the used catalysts could be simultaneously carried out and combined with the proposed life cycle of borohydrides.

  17. Self-Printing on Graphitic Nanosheets with Metal Borohydride Nanodots for Hydrogen Storage

    Science.gov (United States)

    Li, Yongtao; Ding, Xiaoli; Zhang, Qingan

    2016-01-01

    Although the synthesis of borohydride nanostructures is sufficiently established for advancement of hydrogen storage, obtaining ultrasmall (sub-10 nm) metal borohydride nanocrystals with excellent dispersibility is extremely challenging because of their high surface energy, exceedingly strong reducibility/hydrophilicity and complicated composition. Here, we demonstrate a mechanical-force-driven self-printing process that enables monodispersed (~6 nm) NaBH4 nanodots to uniformly anchor onto freshly-exfoliated graphitic nanosheets (GNs). Both mechanical-forces and borohydride interaction with GNs stimulate NaBH4 clusters intercalation/absorption into the graphite interlayers acting as a ‘pen’ for writing, which is accomplished by exfoliating GNs with the ‘printed’ borohydrides. These nano-NaBH4@GNs exhibit favorable thermodynamics (decrease in ∆H of ~45%), rapid kinetics (a greater than six-fold increase) and stable de-/re-hydrogenation that retains a high capacity (up to ~5 wt% for NaBH4) compared with those of micro-NaBH4. Our results are helpful in the scalable fabrication of zero-dimensional complex hydrides on two-dimensional supports with enhanced hydrogen storage for potential applications. PMID:27484735

  18. Platinum-rare earth cathodes for direct borohydride-peroxide fuel cells

    Science.gov (United States)

    Cardoso, D. S. P.; Santos, D. M. F.; Šljukić, B.; Sequeira, C. A. C.; Macciò, D.; Saccone, A.

    2016-03-01

    Hydrogen peroxide (H2O2) is being actively investigated as an oxidant for direct borohydride fuel cells. Herein, platinum-rare earth (RE = Sm, Dy, Ho) alloys are prepared by arc melting and their activity for hydrogen peroxide reduction reaction (HPRR) is studied in alkaline media. Cyclic voltammetry and chronoamperometry measurements show that Pt-Sm electrode displays the highest catalytic activity for HPRR with the lowest activation energy, followed by Pt-Ho, while Pt-Dy alloys show practically no activity. Laboratory direct borohydride-peroxide fuel cells (DBPFCs) are assembled using these alloys. The DBPFC with Pt-Sm cathode gives the highest peak power density of 85 mW cm-2, which is more than double of that obtained in a DBPFC with Pt electrodes.

  19. Studies on sodium-borohydride-reducible hexose in glucosyl-albumin.

    Science.gov (United States)

    Sharma, K K; Rai, K B; Pattabiraman, T N

    1983-08-01

    Glucosylated albumin of human serum isolated by dye-ligand chromatography on blue Sepharose, was not found to be completely reducible by sodium borohydride. The percentage reducible hexose as judged by phenol-sulphuric acid reaction was in the range of 49.7 +/- 12.8 in control subjects (n = 24) and 53.8 +/- 14.2 in diabetics (n = 50). Increase in the level of total hexose bound to albumin and reducible hexose were equally significant in diabetes (P less than 0.001). Sodium chloride gradient elution during chromatography on blue Sepharose showed that glucosylated albumin had lesser affinity than the native protein to the matrix. It is proposed that an addition product between hexose and albumin is formed during nonenzymatic reaction and this adduct is fairly stable and is not reducible by sodium borohydride. PMID:6626188

  20. Investigations on the structure and properties of novel mixed-metal borohydrides

    OpenAIRE

    Schouwink, Pascal

    2014-01-01

    This thesis deals with structural topologies of different dimensionalities in novel complex hydrides based on the tetrahydroborate anion. While classical applications of hydrides such as mobile hydrogen storage are discussed, the use of hydrogen-storage incompatible heavy metals, in especial lanthanides, yields new structural features and functionalities in borohydride chemistry. In this context, the photophysical properties as well as extensive structural dynamics provide means of venturing ...

  1. Investigation of the porous nanostructured Cu/Ni/AuNi electrode for sodium borohydride electrooxidation

    International Nuclear Information System (INIS)

    An electrochemical approach to nanostructured Cu/Ni/AuNi catalyst design using the electrodeposition process followed by galvanic replacement technique is presented. The procedure consisted of the electrodeposition of Ni–Zn on the Ni coating with subsequent replacement of the zinc by gold at open circuit potential in a gold containing alkaline solution. The surface morphologies and compositions of coatings were determined by energy dispersive X-ray and scanning electron microscopy techniques. The results showed that the Cu/Ni/AuNi coatings were porous composing of discrete Au nanoparticles. The electrocatalytic activity of Cu/Ni/AuNi electrodes for sodium borohydride electro-oxidation was studied using cyclic voltammetry, chronoamperometry, chronopotentiometry and electrochemical impedance spectroscopy techniques. The electro-oxidation current on Cu/Ni/AuNi catalyst is much higher than that on flat Au catalyst. The onset potential and peak potential on Cu/Ni/AuNi catalysts are more negative than that on flat Au catalyst for borohydride electrooxidation. The impedance behavior also shows different patterns, capacitive, and negative resistances and inductive loops at different applied anodic potentials. All results show that the Cu/Ni/AuNi catalysts can be applied as potential anode catalysts for the direct borohydride fuel cells

  2. Borohydride-reducible components in soluble collagen irradiated with gamma rays in solution

    International Nuclear Information System (INIS)

    Irradiation with 100 krad of gamma rays of neutral-soluble rat skin collagen decreased the content of aldol cross-links by a factor of three, whereas it did not affect the content of allysine. On reduction with tritiated sodium borohydride, five new components were detected showing different stability towards acid and alkali. (author) tetracycline. The results of kinetic and autoradiographic studies and microscopical analysis of bone preparations suggest that stable strontium inhibits the mineralization of newly formed bone tissue without affecting the physicochemical processes related to ion exchange. (author)

  3. Innovative reactor prototype for Hydrogen production in a stationary application using sodium borohydride

    OpenAIRE

    Barbosa, Rui; Ferreira, V.; Silva, D; Condes, J.; Ramos, S.; Amaral, V.; Pinto, A. M. F. R.; Figueiredo, A; Rangel, C. M.

    2011-01-01

    Hydrogen storage has proved to be the greatest obstacle preventing hydrogen from replacing fossil fuels. Hence, a safe, efficient and economical method of storing hydrogen must be available to turn viable a hydrogen economy based on renewable resources [1]. Hydrogen can be stored in chemical hydrides such as sodium borohydride (NaBH4), with large theoretical H2 content of 10,9 wt%. With the aid of catalysts, and at room temperatures, the alkaline hydrolysis of NaBH4 can be enhanced [2]. In th...

  4. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    International Nuclear Information System (INIS)

    The system Li–A–Y–BH4 (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y3+ is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH4 both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A3Y(BH4)6 or c-A2LiY(BH4)6 (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH4)4 crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH4 (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y3+ is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH4)4 structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH4 (A=K, Rb, Cs) contains nine compounds in total. • Y3+ forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH4)4 crystallize with structure types analogous to metal oxides. • Double-perovskites decompose and form a novel borohydride-closo-borane

  5. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    Energy Technology Data Exchange (ETDEWEB)

    Sadikin, Yolanda [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Stare, Katarina [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerjeva 5, SI-1000 Ljubljana (Slovenia); Schouwink, Pascal [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Brix Ley, Morten; Jensen, Torben R. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Århus C (Denmark); Meden, Anton [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerjeva 5, SI-1000 Ljubljana (Slovenia); Černý, Radovan, E-mail: radovan.cerny@unige.ch [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland)

    2015-05-15

    The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y{sup 3+} is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH{sub 4} both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A{sub 3}Y(BH{sub 4}){sub 6} or c-A{sub 2}LiY(BH{sub 4}){sub 6} (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH{sub 4}){sub 4} crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y{sup 3+} is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH{sub 4}){sub 4} structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH{sub 4} (A=K, Rb, Cs) contains nine compounds in total. • Y{sup 3+} forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH{sub 4}){sub 4} crystallize with

  6. Batch sodium borohydride hydrolysis systems: Effect of sudden valve opening on hydrogen generation rate

    OpenAIRE

    M. J. F. Ferreira; Coelho, F; Rangel, C. M.; Pinto, A. M. F. R.

    2012-01-01

    A study was undertaken in order to investigate the potential of hydrogen (H 2) generation by hydrolysis of sodium borohydride solution (10 wt% NaBH 4 and 7 wt% NaOH), in batch reactors, operating at moderate pressures (up to #8764;1.2 MPa), in the presence of a powdered nickel-ruthenium based catalyst, reused between 311 and 316 times, to feed on-demand a proton exchange membrane fuel cell. A different approach to the testing of the performance of the batch NaBH 4 hydrolysis system is explore...

  7. Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

    DEFF Research Database (Denmark)

    Hummelshøj, Jens Strabo; Landis, David; Voss, Johannes;

    2009-01-01

    We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...... metal atom (M2) plus two to five (BH4)− groups, i.e., M1M2(BH4)2–5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with...

  8. The borohydride oxidation reaction on La-Ni-based hydrogen-storage alloys.

    Science.gov (United States)

    Paschoalino, Waldemir J; Thompson, Stephen J; Russell, Andrea E; Ticianelli, Edson A

    2014-07-21

    This work provides insights into the processes involved in the borohydride oxidation reaction (BOR) in alkaline media on metal hydride alloys formed by LaNi(4.7)Sn(0.2)Cu(0.1) and LaNi(4.78)Al(0.22) with and without deposited Pt, Pd, and Au. The results confirm the occurrence of hydrolysis of the borohydride ions when the materials are exposed to BH(4)(-) and a continuous hydriding of the alloys during BH(4)(-) oxidation measurements at low current densities. The activity for the direct BOR is low in both bare metal hydride alloys, but the rate of the BH(4)(-) hydrolysis and the hydrogen-storage capacity are higher, while the rate of H diffusion is slower for bare LaNi(4.78) Al(0.22). The addition of Pt and Pd to both alloys results in an increase of the BH(4)(-) hydrolysis, but the H(2) formed is rapidly oxidized at the Pt-modified catalysts. In the case of Au modification, a small increase in the BH(4)(-) hydrolysis is observed as compared to the bare alloys. The presence of Au and Pd also leads to a reduction of the rates of alloy hydriding/de-hydriding. PMID:24700670

  9. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells

    Indian Academy of Sciences (India)

    N A Choudhury; S K Prashant; S Pitchumani; P Sridhar; A K Shukla

    2009-09-01

    A direct borohydride fuel cell (DBFC) employing a poly (vinyl alcohol) hydrogel membrane electrolyte (PHME) is reported. The DBFC employs an AB5 Misch metal alloy as anode and a goldplated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium borohydride as fuel and aqueous acidified solution of hydrogen peroxide as oxidant. Room temperature performances of the PHME-based DBFC in respect of peak power outputs; ex-situ cross-over of oxidant, fuel, anolyte and catholyte across the membrane electrolytes; utilization efficiencies of fuel and oxidant, as also cell performance durability are compared with a similar DBFC employing a Nafion®-117 membrane electrolyte (NME). Peak power densities of ∼30 and ∼40 mW cm-2 are observed for the DBFCs with PHME and NME, respectively. The crossover of NaBH4 across both the membranes has been found to be very low. The utilization efficiencies of NaBH4 and H2O2 are found to be ∼24 and ∼59%, respectively for the PHME-based DBFC; ∼18 and ∼62%, respectively for the NME-based DBFC. The PHME and NME-based DBFCs exhibit operational cell potentials of ∼ 1.2 and ∼ 1.4 V, respectively at a load current density of 10 mA cm-2 for ∼100 h.

  10. Solid-state Asymmetric Reduction of (S)-1, l'-Bi-2-naphtholAcetylferrocene Molecular Compound with Sodium Borohydride

    Institute of Scientific and Technical Information of China (English)

    MENG, Ji-Ben; DU, Hai-Feng; DING, Kui-Ling

    2001-01-01

    A novel molecular crystal formed between enanteopure 1,l'bi-2-naphthoi and acetylferrocene has been prepared andcharacterized in this communication. The examination on itsreducton with soditma borohydride showed that the asymnetric inducton was observed in the solid state but not in the solution phase. The asymmetric induction in the solid-state reaction may be attributed to the chiral microenviromnent ofmolecular crystal.

  11. A new route for the synthesis of reduced transition metal oxides using borohydrides

    Energy Technology Data Exchange (ETDEWEB)

    Manthiram, A.; Zhu, Y.T.; Dananjay, A. [Univ. of Texas, Austin, TX (United States). Center for Materials Science and Engineering

    1994-12-31

    Reduction of aqueous solutions of tungstates, molybdates or vanadates by aqueous alkali metal borohydrides at ambient-temperature results in a formation of dark colored gel. The gel is amorphous to X-ray diffraction and crystallizes sharply at around 300--500 C to yield reduced transition metal oxides such as the oxide bronzes, Na{sub x}M{sub y}O{sub z}, or the binary oxides, MO{sub 2} (M = V, Mo or W). The nature and composition of the products formed are strongly influenced by the reaction conditions such as the reaction pH as well as the concentration and amount of the reagents. Experimental procedures to obtain the different phases are presented. This novel low-temperature approach has a potential to access new metastable phases.

  12. Studies on the sodium borohydride reduction of unsaturated keto nucleosides. Novel route to deoxy nucleosides

    International Nuclear Information System (INIS)

    Reduction of α,β-unsaturated (ketohexosyl)purines, which constitute the first examples of unsaturated keto nucleosides, with sodium borohydride gave the corresponding deoxy nucleosides. Contrary to the recently reported (4',6'-dideoxy-β-L-glycero-hex3'-enopyranosulosyl)purines, which were obtained by acetylation of the corresponding keto nucleosides, the α anomer, subsequently described, was prepared by oxidation of the partially protected deoxyhexosylpurine. The mechanisms of these reductions were established by a study of the NMR spectra of the deoxy nucleosides using NaBH4 in deuterated solvents and sodium borodeuteride in light solvents. 1,2 addition of the hydride was shown to be the mode of reduction of all the studied α- and β-unsaturated keto nucleosides. The ready availability of these unsaturated keto nucleosides provides extremely useful synthetic intermediate nucleosides especially for the preparation of nucleosides containing rare deoxy sugars

  13. Tritium and deuterium labelling studies of alkali metal borohydrides and their application to simple reductions

    International Nuclear Information System (INIS)

    Simple and facile syntheses of highly deuterated and tritiated LiBH4, NaBH4 and KBH4 were achieved by hydrogen isotope exchange with deuterium or tritium gas at elevated temperatures. The exchange products were characterized by boron, proton and deuterium or tritium NMR spectroscopy. The extent of isotope (2H or 3H) incorporation was calculated from the patterns of 11B NMR spectra. Several samples of tritiated NaBH4 were treated with BF3-Et2O to produce tritiated borane-THF complex, which is an electrophilic reducing agent. The utility of both the borohydride reagents and borane-THF complex in labelling reactions was confirmed by exemplary reductions leading to specifically labelled products. The extent and orientation of labelling in the reduction products was assessed by a combination of radio-HPLC analysis, 1H, 2H or 3H NMR and mass spectrometry. (author)

  14. Rare earth metal oxides as BH4-tolerance cathode electrocatalysts for direct borohydride fuel cells

    Institute of Scientific and Technical Information of China (English)

    NI Xuemin; WANG Yadong; GUO Feng; YAO Pei; PAN Mu

    2012-01-01

    Rare earth metal oxides (REMO) as cathode electrocatalysts in direct borohydride fuel cell (DBFC) were investigated.The REMO electrocatalysts tested showed favorable activity to the oxygen electro-reduction reaction and strong tolerance to the attack of BH4- in alkaline electrolytes.The simple membraneless DBFCs using REMO as cathode electrocatalyst and using hydrogen storage alloy as anodic electrocatalyst exhibited an open circuit of about 1 V and peak power of above 60 mW/cm2.The DBFC using Sm2O3 as cathode electrocatalyst showed a relatively better performance.The maximal power density of 76.2 mW/cm2 was obtained at the cell voltage of 0.52 V.

  15. Electrochemical oxidation of sodium borohydride on carbon supported Pt-Zn nanoparticle bimetallic catalyst and its implications to direct borohydride-hydrogen peroxide fuel cell

    International Nuclear Information System (INIS)

    Highlights: • The Pt-Zn/C catalyst as anode catalyst for DBHFC were facilely synthesized. • The average particle size of Pt-Zn bimetallic nanoparticles is approximately 2.5 nm. • The Zn-doping can apparently improve the catalytic activity for BH4− electrochemical oxidation. • The maximum power density of DBHFC employing Pt-Zn/C as anode catalyst is as high as 79.9 mW cm−2 at 79.5 mA cm−2 and 25 °C. - Abstract: Carbon supported Pt-Zn bimetallic nanoparticle electrocatalysts (Pt-Zn/C) are facilely prepared by a modified NaBH4 reduction method in aqueous solution at room temperature and investigated as alternative anode catalysts for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared nanospherical electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and fuel cell test. Based on results of TEM and XRD, the Pt-Zn nanoparticles show average particle size of approximately 2.5 nm on the carbon surface. The fundamental electrochemical results show that the Pt-Zn/C catalysts exhibit much higher catalytic activity and stability for the direct oxidation of BH4− than Pt/C catalyst since Pt atoms are partly substituted by Zn atoms in Pt-Zn catalyst. Among various Pt-Zn catalysts with different compositions, the Pt67Zn33/C catalyst presents the highest catalytic activity for BH4− electrooxidation. The DBHFC using Pt67Zn33/C as anode catalyst and Pt/C as cathode catalyst obtains the maximum power density as high as 79.9 mW cm−2 at 79.5 mA cm−2 and 25 °C

  16. Simultaneous desorption behavior of M borohydrides and Mg2FeH6 reactive hydride composites (M = Mg, then Li, Na, K, Ca)

    Science.gov (United States)

    Chaudhary, Anna-Lisa; Li, Guanqiao; Matsuo, Motoaki; Orimo, Shin-ichi; Deledda, Stefano; Sørby, Magnus H.; Hauback, Bjørn C.; Pistidda, Claudio; Klassen, Thomas; Dornheim, Martin

    2015-08-01

    Combinations of complex metal borohydrides ball milled with the transition metal complex hydride, Mg2FeH6, are analysed and compared. Initially, the Reactive Hydride Composite (RHC) of Mg2+ cation mixtures of Mg2FeH6 and γ-Mg(BH4)2 is combined in a range of molar ratios and heated to a maximum of 450 °C. For the molar ratio of 6 Mg2FeH6 + Mg(BH4)2, simultaneous desorption of the two hydrides occurred, which resulted in a single event of hydrogen release. This single step desorption occurred at temperatures between those of Mg2FeH6 and γ-Mg(BH4)2. Keeping this anionic ratio constant, the desorption behavior of four other borohydrides, Li-, Na-, K-, and Ca-borohydrides was studied by using materials ball milled with Mg2FeH6 applying the same milling parameters. The mixtures containing Mg-, Li-, and Ca-borohydrides also released hydrogen in a single event. The Mass Spectrometry (MS) results show a double step reaction within a narrow temperature range for both the Na- and K-borohydride mixtures. This phenomenon, observed for the RHC systems at the same anionic ratio with all five light metal borohydride mixtures, can be described as simultaneous hydrogen desorption within a narrow temperature range centered around 300 °C.

  17. PtRu-LiCoO 2—an efficient catalyst for hydrogen generation from sodium borohydride solutions

    Science.gov (United States)

    Krishnan, Palanichamy; Yang, Tae-Hyun; Lee, Won-Yong; Kim, Chang-Soo

    Hydrogen generation by the hydrolysis of aqueous sodium borohydride (NaBH 4) solutions is studied using IRA-400 anion resin dispersed Pt, Ru catalysts and lithium cobalt oxide (LiCoO 2) supported Pt, Ru and PtRu catalysts. The performance of the LiCoO 2 supported catalysts is better than that of ion-exchange resin dispersed catalysts. There is a marked concentration dependence on the performance of the LiCoO 2 supported catalysts and the hydrogen generation rate decreases if the borohydride concentration is increased beyond 10 wt.%. The efficiency of PtRu-LiCoO 2 is almost double that of either Ru-LiCoO 2 or Pt-LiCoO 2 for NaBH 4 concentrations up to 10 wt.%.

  18. Ultrafast and stable hydrogen generation from sodium borohydride in methanol and water over Fe-B nanoparticles

    Science.gov (United States)

    Ocon, Joey D.; Tuan, Trinh Ngoc; Yi, Youngmi; de Leon, Rizalinda L.; Lee, Jae Kwang; Lee, Jaeyoung

    2013-12-01

    Use of environmentally friendly hydrogen as fuel on a massive scale requires efficient storage and generation systems. Chemical hydrides, such as sodium borohydride (NaBH4), have the capacity to meet these needs as demonstrated by its high hydrogen storage efficiency. Here, we first report the catalytic activity of Fe-B nanoparticles supported on porous Ni foam - synthesized via a simple chemical reduction technique - for hydrogen generation from the mixtures of NaBH4, H2O, and CH3OH. Activation energies of the catalyzed hydrolysis (64.26 kJ mol-1) and methanolysis (7.02 kJ mol-1) are notably lower than other metal-boron catalysts previously reported. Methanol, in combination with a cheap but highly active Fe-B nanocatalysts, provides ultrafast rates of low temperature hydrogen generation from the sodium borohydride solutions.

  19. Durability and reutilization capabilities of a Ni-Ru catalyst for the hydrolysis of sodium borohydride in batch reactors

    OpenAIRE

    Pinto, A.M.F.R.; M.J.F. Ferreira; Fernandes, V. R.; Rangel, C. M.

    2011-01-01

    The study of catalyst durability and reutilization on catalyzed hydrolysis of sodium borohydride is essential from an application point of view. Few works on this topic are available in the literature. In the present work, a powder nickel-ruthenium based catalyst, unsupported, used in two different schemes of NaBH 4 hydrolysis (alkaline and alkali free hydrolysis), performed in batch reactors with different volumes and bottom geometries (flat and conical), was investigated in terms of durabil...

  20. Probing molecular dynamics of metal borohydrides on the surface of mesoporous scaffolds by multinuclear high resolution solid state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Son-Jong, E-mail: Sonjong@cheme.caltech.edu [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Hyun-Sook [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); To, Magnus [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Young-Su; Cho, Young Whan [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Choi, Hyungkeun; Kim, Chul [Department of Chemistry, Hannam University, Daejeon 305-811 (Korea, Republic of)

    2015-10-05

    Graphical abstract: In situ variable temperature multinuclear solid state NMR allows to probe surface wetting, diffusivity, and confinement of metal borohydrides into nanopores. - Abstract: Understanding of surface interactions between borohydride molecules and the surfaces of porous supports have gained growing attention for successful development of nano-confinement engineering. By use of in situ variable temperature (VT) magic angle spinning (MAS) NMR, molecular mobility changes of LiBH{sub 4} crystalline solid has been investigated in the presence of silica based and carbonaceous surfaces. Spin–spin J-coupling of {sup 1}H–{sup 11}B in LiBH{sub 4} was monitored in series of VT NMR spectra to probe translational mobility of LiBH{sub 4} that appeared to be greatly enhanced upon surface contact. Such enhanced diffusivity was found to be effective in the formation of solid solution and co-confinement with other metal borohydrides. Co-confinement of LiBH{sub 4}–Ca(BH{sub 4}){sub 2} mixture was demonstrated at temperature as low as 100 °C, much lower than the reported bulk eutectic melting temperature. The discovery adds a novel property of LiBH{sub 4} that has been proven to be highly versatile in many energy related applications.

  1. Nuclear magnetic resonance studies of atomic motion in borohydride-based materials: Fast anion reorientations and cation diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Skripov, A.V., E-mail: skripov@imp.uran.ru; Soloninin, A.V.; Babanova, O.A.; Skoryunov, R.V.

    2015-10-05

    Highlights: • Solid solutions LiBH{sub 4}–LiI: extremely fast BH{sub 4} reorientations down to low T. • LiLa(BH{sub 4}){sub 3}Cl: Li-ion diffusive jumps and BH{sub 4} reorientations at the same frequency scale. • Dramatic acceleration of B{sub 12}H{sub 12} reorientations in the disordered phase of Na{sub 2}B{sub 12}H{sub 12}. • Fast Na-ion diffusion in the disordered phase of Na{sub 2}B{sub 12}H{sub 12}. - Abstract: Two basic types of thermally activated atomic jump motion are known to exist in solid borohydrides and the related systems: the reorientations of complex anions ([BH{sub 4}]{sup −}, [B{sub 12}H{sub 12}]{sup 2−}) and the translational diffusion of metal cations or complex anions. This paper reviews recent progress in nuclear magnetic resonance (NMR) studies of these jump processes in complex hydrides, such as solid solutions of halide anions in borohydrides, bimetallic borohydrides and borohydride–chlorides, borohydride–amides, and B{sub 12}H{sub 12}-based compounds. The emphasis is put on the systems showing fast-ion conductivity. For these systems, we discuss a possible relation between the reorientational motion of complex anions and the translational motion of metal cations.

  2. Probing molecular dynamics of metal borohydrides on the surface of mesoporous scaffolds by multinuclear high resolution solid state NMR

    International Nuclear Information System (INIS)

    Graphical abstract: In situ variable temperature multinuclear solid state NMR allows to probe surface wetting, diffusivity, and confinement of metal borohydrides into nanopores. - Abstract: Understanding of surface interactions between borohydride molecules and the surfaces of porous supports have gained growing attention for successful development of nano-confinement engineering. By use of in situ variable temperature (VT) magic angle spinning (MAS) NMR, molecular mobility changes of LiBH4 crystalline solid has been investigated in the presence of silica based and carbonaceous surfaces. Spin–spin J-coupling of 1H–11B in LiBH4 was monitored in series of VT NMR spectra to probe translational mobility of LiBH4 that appeared to be greatly enhanced upon surface contact. Such enhanced diffusivity was found to be effective in the formation of solid solution and co-confinement with other metal borohydrides. Co-confinement of LiBH4–Ca(BH4)2 mixture was demonstrated at temperature as low as 100 °C, much lower than the reported bulk eutectic melting temperature. The discovery adds a novel property of LiBH4 that has been proven to be highly versatile in many energy related applications

  3. Direct rotating ring-disk measurement of the sodium borohydride diffusion coefficient in sodium hydroxide solutions

    International Nuclear Information System (INIS)

    This paper presents the experimental determination of the diffusion coefficient of borohydride anion and solution kinematic viscosity for a large panel of NaOH + NaBH4 electrolytic solutions relevant for use as anolyte in Direct Borohydride Fuel Cells (DBFC). The diffusion coefficients have been measured by the transit-time technique on gold rotating ring-disk electrodes, and verified using other classical techniques reported in the literature, namely the Levich method and Electrochemical Impedance Spectroscopy on a gold RDE, or chronoamperometry at a gold microdisk. The agreement between these methods is generally good. The diffusion coefficients measured from the RRDE technique are however ca. twice larger than those previously reported in the literature (e.g. ca. 3 x 10-5 cm2 s-1 in 1 M NaOH + 0.01 M NaBH4 at 25 deg. C in the present study vs. ca. 1.6 x 10-5 cm2 s-1 in 1 M NaOH + 0.02 M NaBH4 at 30 deg. C in the literature, as measured by chronoamperometry at a gold microsphere), which is thoroughly discussed. Our measurements using chronoamperometry at a gold microdisk showed that such technique can yield diffusion coefficient values below what expected. The origin of such finding is explained in the frame of the formation of both a film of boron-oxide(s) at the surface of the (static) gold microdisk and the generation of H2 bubbles at the electrode surface (as a result of the heterogeneous hydrolysis at Au), which alter the access to the electrode surface and thus prevents efficient measurements. Such film formation and H2 bubbles generation is not so much of an issue for rotating electrodes thanks to the convection of electrolyte which sweeps the electrode surface. In addition, should such film be present, the transit-time determination technique on a RRDE displays the advantage of not being very sensible to its presence: the parameter measured is the time taken by a perturbation generated the disk to reach the ring trough a distance several orders of

  4. Direct rotating ring-disk measurement of the sodium borohydride diffusion coefficient in sodium hydroxide solutions

    Energy Technology Data Exchange (ETDEWEB)

    Chatenet, M. [Laboratoire d' Electrochimie et de Physico-chimie des Materiaux et des Interfaces, LEPMI, UMR 5631 CNRS/Grenoble-INP/UJF, 1130 rue de la piscine, BP75, 38402 Saint Martin d' Heres Cedex (France)], E-mail: Marian.Chatenet@phelma.grenoble-inp.fr; Molina-Concha, M.B. [Laboratoire d' Electrochimie et de Physico-chimie des Materiaux et des Interfaces, LEPMI, UMR 5631 CNRS/Grenoble-INP/UJF, 1130 rue de la piscine, BP75, 38402 Saint Martin d' Heres Cedex (France); El-Kissi, N. [Laboratoire de Rheologie, UMR 5520 CNRS/Grenoble-INP/UJF, 1301 rue de la piscine, 38041 Grenoble Cedex 9 (France); Parrour, G.; Diard, J.-P. [Laboratoire d' Electrochimie et de Physico-chimie des Materiaux et des Interfaces, LEPMI, UMR 5631 CNRS/Grenoble-INP/UJF, 1130 rue de la piscine, BP75, 38402 Saint Martin d' Heres Cedex (France)

    2009-07-15

    This paper presents the experimental determination of the diffusion coefficient of borohydride anion and solution kinematic viscosity for a large panel of NaOH + NaBH{sub 4} electrolytic solutions relevant for use as anolyte in Direct Borohydride Fuel Cells (DBFC). The diffusion coefficients have been measured by the transit-time technique on gold rotating ring-disk electrodes, and verified using other classical techniques reported in the literature, namely the Levich method and Electrochemical Impedance Spectroscopy on a gold RDE, or chronoamperometry at a gold microdisk. The agreement between these methods is generally good. The diffusion coefficients measured from the RRDE technique are however ca. twice larger than those previously reported in the literature (e.g. ca. 3 x 10{sup -5} cm{sup 2} s{sup -1} in 1 M NaOH + 0.01 M NaBH{sub 4} at 25 deg. C in the present study vs. ca. 1.6 x 10{sup -5} cm{sup 2} s{sup -1} in 1 M NaOH + 0.02 M NaBH{sub 4} at 30 deg. C in the literature, as measured by chronoamperometry at a gold microsphere), which is thoroughly discussed. Our measurements using chronoamperometry at a gold microdisk showed that such technique can yield diffusion coefficient values below what expected. The origin of such finding is explained in the frame of the formation of both a film of boron-oxide(s) at the surface of the (static) gold microdisk and the generation of H{sub 2} bubbles at the electrode surface (as a result of the heterogeneous hydrolysis at Au), which alter the access to the electrode surface and thus prevents efficient measurements. Such film formation and H{sub 2} bubbles generation is not so much of an issue for rotating electrodes thanks to the convection of electrolyte which sweeps the electrode surface. In addition, should such film be present, the transit-time determination technique on a RRDE displays the advantage of not being very sensible to its presence: the parameter measured is the time taken by a perturbation generated the

  5. Sodium borohydride as an additive to enhance the performance of direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lianqin; Fang, Xiang; Shen, Pei Kang [The Key Laboratory of Low-carbon Chemistry and Energy Conservation of Guangdong Province, The State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275 (China); Bambagioni, Valentina; Bevilacqua, Manuela; Bianchini, Claudio; Filippi, Jonathan; Lavacchi, Alessandro; Marchionni, Andrea; Vizza, Francesco [Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence (Italy)

    2010-12-15

    The effect of adding small quantities (0.1-1 wt.%) of sodium borohydride (NaBH{sub 4}) to the anolyte solution of direct ethanol fuel cells (DEFCs) with membrane-electrode assemblies constituted by nanosized Pd/C anode, Fe-Co cathode and anion-exchange membrane (Tokuyama A006) was investigated by means of various techniques. These include cyclic voltammetry, in situ FTIR spectroelectrochemistry, a study of the performance of monoplanar fuel cells and an analysis of the ethanol oxidation products. A comparison with fuel cells fed with aqueous solutions of ethanol proved unambiguously the existence of a promoting effect of NaBH{sub 4} on the ethanol oxidation. Indeed, the potentiodynamic curves of the ethanol-NaBH{sub 4} mixtures showed higher power and current densities, accompanied by a remarkable increase in the fuel consumption at comparable working time of the cell. A {sup 13}C and {sup 11}B {l_brace}{sup 1}H{r_brace}NMR analysis of the cell exhausts and an in situ FTIR spectroelectrochemical study showed that ethanol is converted selectively to acetate while the oxidation product of NaBH{sub 4} is sodium metaborate (NaBO{sub 2}). The enhancement of the overall cell performance has been explained in terms of the ability of NaBH{sub 4} to reduce the PdO layer on the catalyst surface. (author)

  6. Structure determination of ultra dense magnesium borohydride: A first-principles study

    Science.gov (United States)

    Fan, Jing; Duan, Defang; Jin, Xilian; Bao, Kuo; Liu, Bingbing; Cui, Tian

    2013-06-01

    Magnesium borohydride (Mg(BH4)2) is one of the potential hydrogen storage materials. Recently, two experiments [Y. Filinchuk, B. Richter, T. R. Jensen, V. Dmitriev, D. Chernyshov, and H. Hagemann, Angew. Chem., Int. Ed. 50, 11162 (2011);, 10.1002/anie.201100675 L. George, V. Drozd, and S. K. Saxena, J. Phys. Chem. C 113, 486 (2009), 10.1021/jp807842t] found that α-Mg(BH4)2 can irreversibly be transformed to an ultra dense δ-Mg(BH4)2 under high pressure. Its volumetric hydrogen content at ambient pressure (147 g/cm3) exceeds twice of DOE's (U.S. Department of Energy) target (70 g/cm3) and that of α-Mg(BH4)2 (117 g/cm3) by 20%. In this study, the experimentally proposed P42nm structure of δ-phase has been found to be dynamically unstable. A new Fddd structure has been reported as a good candidate of δ-phase instead. Its enthalpy from 0 to 12 GPa is much lower than P42nm structure and the simulated X-ray diffraction spectrum is in satisfied agreement with previous experiments. In addition, the previously proposed P-3m1 structure, which is denser than Fddd, is found to be a candidate of ɛ-phase due to the agreement of Raman shifts.

  7. (Iminophosphoranyl)(thiophosphoranyl)methane rare-earth borohydride complexes: synthesis, structures and polymerization catalysis.

    Science.gov (United States)

    Schmid, Matthias; Oña-Burgos, Pascual; Guillaume, Sophie M; Roesky, Peter W

    2015-07-21

    The (iminophosphoranyl)(thiophosphoranyl)methanide {CH(PPh2=NSiMe3)(PPh2=S)}(-) ligand has been used for the synthesis of divalent and trivalent rare-earth borohydride complexes. The salt metathesis of the potassium reagent [K{CH(PPh2=NSiMe3)(PPh2=S)}]2 with [Yb(BH4)2(THF)2] resulted in the divalent monoborohydride ytterbium complex [{CH(PPh2=NSiMe3)(PPh2=S)}Yb(BH4)(THF)2]. The 2D (31)P/(171)Yb HMQC-NMR spectrum clearly showed the coupling between both nuclei. The trivalent bisborohydrides [{CH(PPh2=NSiMe3)(PPh2=S)}Ln(BH4)2(THF)] (Ln = Y, Sm, Tb, Dy, Er, Yb and Lu) were obtained by reaction of [K{CH(PPh2=NSiMe3)(PPh2=S)}]2 with [Ln(BH4)3(THF)3]. All new compounds were characterized by single X-ray diffraction. The divalent and trivalent compounds were next used as initiators in the ring-opening polymerization (ROP) of ε-caprolactone (CL) and trimethylene carbonate (TMC). All complexes afforded a generally well-controlled ROP of both of these cyclic esters. High molar mass poly(ε-caprolactone) diols (Mn,NMR trimethylene carbonate)s (Mn,NMR < 20,000 g mol(-1), ĐM = 1.61) were thus synthesized under mild operating conditions. PMID:25683468

  8. Reductive reactivity of borohydride- and dithionite-synthesized iron-based nanoparticles: A comparative study.

    Science.gov (United States)

    Ma, Xiaoming; He, Di; Jones, Adele M; Collins, Richard N; Waite, T David

    2016-02-13

    In this study sodium dithionite (NaS2O4) and sodium borohydride (NaBH4) were employed as reducing agents for the synthesis of nanosized iron-based particles. The particles formed using NaBH4 (denoted nFe(BH4)) principally contained (as expected) Fe(0) according to XAS and XRD analyses while the particles synthesized using NaS2O4, (denoted nFe(S2O4)) were dominated by the mixed Fe(II)/Fe(III) mineral magnetite (Fe3O4) though with possible presence of Fe(0). The ability of both particles to reduce trichloroethylene (TCE) under analogous conditions demonstrated remarkable differences with nFe(BH4) resulting in complete reduction of 1.5mM of TCE in 2h while nFe(S2O4) were unable to effect complete reduction of TCE in 120 h. Moreover, acetylene was the major reaction product formed in the presence of nFe(S2O4) while the major reaction product formed following reaction with nFe(BH4) was ethylene, which was further reduced to ethane as the reaction proceeded. Considering that effective Pd reduction to Pd(0) requires the presence of Fe(0), this is consistent with our finding that Fe(0) is not the dominant phase formed when employing dithionite as a reducing agent under the conditions employed in this study. PMID:26513569

  9. Formation of borohydride-reduced nickel-boron coatings on various steel substrates

    Science.gov (United States)

    Vitry, V.; Delaunois, F.

    2015-12-01

    Electroless nickel-boron coatings are widely used in industrial on various substrates: ferrous and non-ferrous alloys mainly but also in some cases non-metallic materials. However, their growth process is still not fully understood and the influence of the nature of the substrate on this process is completely unknown. The formation of electroless nickel-boron was observed on five ferrous alloys: a mild steel, a high carbon unalloyed steel, a cryogenic steel (that contains 9 wt.% nickel), an austenitic stainless steel and an austeno-ferritic (duplex) stainless steel. Nickel-boron films were prepared by electroless deposition, using sodium borohydride as a reducing agent. Samples were immersed in a plating bath for times ranging from 5 s to 60 min. The influence of the nature of the substrate on the initial deposition of the coatings was investigated in detail: the initiation mechanism was identified for all substrates and it was found to be related to catalytic oxidation of the reducing agent rather than to a displacement process. The delay before initiation was influenced by the nickel content of the coating and by a high number of grain boundaries. In all cases, the plating rate varied with plating time, with a slower period during the first 10 min that corresponds to morphological modification of the coating.

  10. Aqueous sodium borohydride induced thermally stable porous zirconium oxide for quick removal of lead ions

    Science.gov (United States)

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-03-01

    Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution.

  11. Alkali free hydrolysis of sodium borohydride for hydrogen generation under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, M.J.F.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Gales, L. [Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto and Instituto de Ciencias Biomedicas Abel Salazar, Largo Prof. Abel Salazar 2, 4099-003 Porto (Portugal); Fernandes, V.R.; Rangel, C.M. [Laboratorio Nacional de Energia e Geologia - LNEG, Fuel Cells and Hydrogen Unit Estrada do Paco do Lumiar 22, 1649-038 Lisboa (Portugal)

    2010-09-15

    The present study is related with the production of hydrogen gas (H{sub 2}), at elevated pressures and with high gravimetric storage density, to supply a PEM fuel cell on-demand. To achieve this goal, solid sodium borohydride (NaBH{sub 4}) was mixed with a proper amount of a powder reused nickel-ruthenium based catalyst (Ni-Ru based/NaBH{sub 4}: 0.2 and 0.4 g/g; {approx}150 times reused) inside the bottom of a batch reactor. Then, a stoichiometric amount of pure liquid water (H{sub 2}O/NaBH{sub 4}: 2-8 mol/mol) was added and the catalyzed NaBH{sub 4} hydrolysis evolved, in the absence of an alkali inhibitor. In this way, this research work is designated alkali free hydrolysis of NaBH{sub 4} for H{sub 2} generation. This type of hydrolysis is excellent from an environmental point of view because it does not involve strongly caustic solutions. Experiments were performed in three batch reactors with internal volumes 646, 369 and 229 cm{sup 3}, and having different bottom geometries (flat and conical shapes). The H{sub 2} generated was a function of the added water and completion was achieved with H{sub 2}O/NaBH{sub 4} = 8 mol/mol. The results show that hydrogen yields and rates increase remarkably increasing both system temperature and pressure. Reactor bottom shape influences deeply H{sub 2} generation: the conical bottom shape greatly enhances the rate and practically eliminates the reaction induction time. Our system of compressed hydrogen generation up to 1.26 MPa shows 6.3 wt% and 70 kg m{sup -3}, respectively, for gravimetric and volumetric hydrogen storage capacities (materials-only basis) and therefore is a viable hydrogen storage candidate for portable applications. (author)

  12. Capacity enhancement of aqueous borohydride fuels for hydrogen storage in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, David; Neiner, Doinita [U.S. Borax Inc., Rio Tinto, Greenwood Village, CO (United States); Bowden, Mark [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA (United States); Whittemore, Sean; Holladay, Jamie [Pacific Northwest National Laboratory, Richland, WA (United States); Huang, Zhenguo [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2500 (Australia); Autrey, Tom [Pacific Northwest National Laboratory, Richland, WA (United States)

    2015-10-05

    Highlights: • Adjusting ratio of Q = Na/B will maximize H{sub 2} storage capacity of liquid carrier. • Mixtures of hydrolysis products are desirable to maximize solubility. • 6.5 wt.% hydrogen and remains liquid from beginning to end. - Abstract: In this work we demonstrate enhanced hydrogen storage capacities through increased solubility of sodium borate product species in aqueous media achieved by adjusting the sodium (NaOH) to boron (B(OH){sub 3}) ratio, i.e., M/B, to obtain a distribution of polyborate anions. For a 1:1 mol ratio of NaOH to B(OH){sub 3}, M/B = 1, the ratio of the hydrolysis product formed from NaBH{sub 4} hydrolysis, the sole borate species formed and observed by {sup 11}B NMR is sodium metaborate, NaB(OH){sub 4}. When the ratio is 1:3 NaOH to B(OH){sub 3}, M/B = 0.33, a mixture of borate anions is formed and observed as a broad peak in the {sup 11}B NMR spectrum. The complex polyborate mixture yields a metastable solution that is difficult to crystallize. Given the enhanced solubility of the polyborate mixture formed when M/B = 0.33 it should follow that the hydrolysis of sodium octahydrotriborate, NaB{sub 3}H{sub 8}, can provide a greater storage capacity of hydrogen for fuel cell applications compared to sodium borohydride while maintaining a single phase. Accordingly, the hydrolysis of a 23 wt.% NaB{sub 3}H{sub 8} solution in water yields a solution having the same complex polyborate mixture as formed by mixing a 1:3 M ratio of NaOH and B(OH){sub 3} and releases >8 eq of H{sub 2}. By optimizing the M/B ratio a complex mixture of soluble products, including B{sub 3}O{sub 3}(OH){sub 5}{sup 2−}, B{sub 4}O{sub 5}(OH){sub 4}{sup 2−}, B{sub 3}O{sub 3}(OH){sub 4}{sup −}, B{sub 5}O{sub 6}(OH){sub 4}{sup −} and B(OH){sub 3}, can be maintained as a single liquid phase throughout the hydrogen release process. Consequently, hydrolysis of NaB{sub 3}H{sub 8} can provide a 40% increase in H{sub 2} storage density compared to the hydrolysis

  13. Carbon-supported Pt0.75M0.25 (M = Ni or Co) electrocatalysts for borohydride oxidation

    International Nuclear Information System (INIS)

    Highlights: • BH4− electrooxidation at carbon supported Pt-alloys (Pt0.75M0.25/C, M = Ni or Co). • Influence of BH4− concentration and temperature on BH4− electrooxidation. • Evaluation of charge transfer coefficients and number of electrons exchanged. • Assessment of heterogeneous rate constants and activation energies. • Higher catalytic activity of Pt0.75M0.25/C than Pt/C for BH4− electrooxidation. -- Abstract: Electrochemical oxidation of sodium borohydride (NaBH4) at carbon-supported platinum (Pt/C) and carbon-supported bimetallic platinum alloys (Pt0.75M0.25/C, with M = Ni or Co) is studied in alkaline media using cyclic voltammetry and linear scan voltammetry with rotating disc electrode. Main kinetic parameters (e.g., charge transfer coefficients, number of electrons exchanged, standard heterogeneous rate constants and activation energies) for NaBH4 oxidation on these electrocatalysts are determined. Results indicate the highest catalytic activity of Pt0.75Ni0.25/C alloy electrocatalyst, followed by Pt0.75Co0.25/C, while the lowest activity is observed for Pt/C electrocatalyst. The influence of electrolyte composition and temperature on NaBH4 electrooxidation at the three materials is also explored. The good performance of these bimetallic alloys makes them a lower cost alternative to single Pt as electrocatalysts for the direct borohydride fuel cell anode

  14. Nanoporous carbon supported platinum-copper nanocomposites as anode catalysts for direct borohydride-hydrogen peroxide fuel cell

    International Nuclear Information System (INIS)

    Highlights: • NPC supported Pt-Cu nanocomposites are used firstly as anode catalysts for DBHFC. • The average size of the Pt-Cu nanocrystals is around 2.3 nm. • The DBHFC with Pt2Cu/NPC anode shows the maximum power density of 89 mW cm−2. -- Abstract: Nanoporous carbon (NPC) supported Pt-Cu nanocomposites (PtxCu/NPC) with different Pt/Cu molar ratios have been successfully synthesized via NaBH4 reduction method and used as anode catalysts for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The as-synthesized PtxCu/NPC electrocatalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammetry (CV), chronoamperometry (CA), rotating disc electrode (RDE) and fuel cell test. It has been found that the PtCu nanoparticles are uniformly dispersed on the surface of the NPC support with average size of about 2.3 nm. Besides, the PtxCu/NPC catalysts show higher activities for borohydride oxidation than that of monometallic Pt/NPC and Vulcan XC-72 carbon supported Pt2Cu (Pt2Cu/XC-72) catalysts. Especially, the DBHFC equipped with Pt2Cu/NPC as anode catalyst shows the maximum power density of 89 mW cm−2 at 25 °C

  15. Improving SERS Detection of Bacillus thuringiensis Using Silver Nanoparticles Reduced with Hydroxylamine and with Citrate Capped Borohydride

    International Nuclear Information System (INIS)

    The development of techniques that could be useful in fields other than biological warfare agents countermeasures such as medical diagnostics, industrial microbiology, and environmental applications have become a very important subject of research. Raman spectroscopy can be used in near field or at long distances from the sample to obtain fingerprinting information of chemical composition of microorganisms. In this research, biochemical components of the cell wall and endospores of Bacillus thuringiensis (Bt) were identified by surface-enhanced Raman scattering (SERS) spectroscopy using silver (Ag) nanoparticles (NPs) reduced by hydroxylamine and borohydride capped with sodium citrate. Activation of hot spots, aggregation and surface charge modification of the NPs, was studied and optimized to obtain signal enhancements from Bt by SERS. Slight aggregation of the NPs as well as surface charge modification to a more acidic ambient was induced using small-size borohydride-reduced NPs in the form of metallic suspensions aimed at increasing the Ag NP-Bt interactions. Hydroxylamine-reduced NPs required slight aggregation and no pH modifications in order to obtain high spectral quality results in bringing out SERS signatures of Bt.

  16. AB5-type Hydrogen Storage Alloy Modified with Ti/Zr Used as Anodic Materials in Borohydride Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Lianbang WANG; Chunan MA; Xinbiao MAO; Yuanming SUN; Seijiro SUDA

    2005-01-01

    Fuel cell using borohydride as the fuel has received much attention. AB5-type hydrogen storage alloy used as the anodic material instead of noble metals has been investigated. In order to restrain the generation of hydrogen and enhance the utilization of borohydride, Ti/Zr metal powders has been added into the parent LmNi4.78Mn0.22 (where Lm is La-richened mischmetal) alloy (LNM) by ball milling and heat treatment methods. It is found that the addition of Ti/Zr metal powders lowers the electrochemical catalytic activity of the electrodes, at the same time, restrains the generation of hydrogen and enhances the utilization of the fuel. All the results show that the hydrogen generation rate or the utilization of the fuel is directly relative to the electrochemical catalytic activity or the discharge capability of the electrodes. The utilization of the fuel increases with discharge current density. It is very important to find a balance between the discharge capability and the utilization of the fuel.

  17. Study of the ultrafast polarization dynamics in lithium borohydride by means of femtosecond X-ray diffraction

    International Nuclear Information System (INIS)

    In this thesis the ultrafast electronic polarisation in the crystalline material lithium borohydride (LiBH4) is examined. The material is excited by a femtosecond long optical pulse and scanned by a likewise short X-ray pulse. Using X-ray scattering the optically induced spatial rearrangement of electronic charge can be directly mapped with atomic spatial resolution. Copper K-alpha X-rays for the experiment are produced in a laboratory table-top laserplasma source with 1 kHz repetition rate. This radiation is then focused on a powdered sample. Debye-Scherrer rings produced from powder diffraction are collected on a large area detector and processed to yield intensity profiles. Using pump-probe technique the change in diffracted intensity, triggered by excitation with a femtosecond optical pulse is examined. The temporal resolution is given by the delay between pump and probe pulse. This way insight is gained into the dynamic electronic evolution of the system. Intensity changes can be correlated to changes in charge density in the relevant material to elucidate structural dynamics on the femtosecond time scale. Lithium borohydride was chosen since it displays necessary characteristics for the exploration of ultrafast electronic polarisation. Up to date there has been no spatially resolved research in the femtosecond regime elucidating this electronic phenomenon. This work presents the ultrafast resonse in Lithiumborhydrid (LiBH4) to strong electronic fields with optical frequencies, which leads to charge relocation accompanied by electronic polarisation.

  18. Zeolite-confined ruthenium(0) nanoclusters catalyst: record catalytic activity, reusability, and lifetime in hydrogen generation from the hydrolysis of sodium borohydride.

    Science.gov (United States)

    Zahmakiran, Mehmet; Ozkar, Saim

    2009-03-01

    Sodium borohydride, NaBH4, has been considered the most attractive hydrogen-storage material for portable fuel cell applications, as it provides a safe and practical means of producing hydrogen. In a recent communication (Zahmakiran, M.; Ozkar, S. Langmuir 2008, 24, 7065), we have reported a record total turnover number (TTON) of 103 200 mol H2/mol Ru and turnover frequency (TOF) up to 33 000 mol H2/mol Ru x h obtained by using intrazeolite ruthenium(0) nanoclusters in the hydrolysis of sodium borohydride. Here we report full details of the kinetic studies on the intrazeolite ruthenium(0) nanoclusters catalyzed hydrolysis of sodium borohydride in both aqueous and basic solutions. Expectedly, the intrazeolite ruthenium(0) nanoclusters show unprecedented catalytic lifetime, TTON = 27 200 mol H2/mol Ru, and TOF up to 4000 mol H2/mol Ru x h in the hydrolysis of sodium borohydride in basic solution (5% wt NaOH) as well. More importantly, the intrazeolite ruthenium(0) nanoclusters are isolable, bottleable, redispersible, and yet catalytically active. They retain 76% or 61% of their initial catalytic activity at the fifth run with a complete release of hydrogen in aqueous and basic medium, respectively. The intrazeolite ruthenium(0) nanoclusters were isolated as black powder and characterized by using a combination of advanced analytical techniques including XRD, HRTEM, TEM-EDX, SEM, XPS, ICP-OES, and N2 adsorption. PMID:19437749

  19. Water co-adsorption and electric field effects on borohydride structures on Os(1 1 1) by first-principles calculations

    International Nuclear Information System (INIS)

    Highlights: ► Difference in Pt, Os electronic structures lead to different borohydride structures. ► Promotion of B–H bond breaking on Os due to water effects. ► Control of borohydride structure on Os catalyst using electric field. -- Abstract: Periodic density functional theory calculations are performed to investigate the nature of the BH4ad and its interaction with H2Oad in the presence of homogenous electric field. We observed a significant charge polarity of BH4ad on Os(1 1 1) and such property could explain the electrostatic interaction with water monomer (Had) with its HOH plane parallel to the surface. This interaction changes the BHad molecular structure to BH3ad + Had. In the presence of homogenous electric field, the water co-adsorption effect is reduced due to the stabilization of H2Oad on the surface and the deviation of the O–H bond from the plane, decreasing the electrostatic interaction between BH4ad and H2Oad. These fundamental findings imply accessible control of borohydride structures on an electrode surface, which could be relevant for direct borohydride fuel cell (DBFC) and reversible hydrogen storage/release applications

  20. Temperature-mediated phase transformation, pore geometry and pore hysteresis transformation of borohydride derived in-born porous zirconium hydroxide nanopowders

    Science.gov (United States)

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-05-01

    Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, pore geometry as well as pore hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or pore forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate pore size, pore volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications.

  1. Electronic structure of nickel(II) and zinc(II) borohydrides from spectroscopic measurements and computational modeling.

    Science.gov (United States)

    Desrochers, Patrick J; Sutton, Christopher A; Abrams, Micah L; Ye, Shengfa; Neese, Frank; Telser, Joshua; Ozarowski, Andrew; Krzystek, J

    2012-03-01

    The previously reported Ni(II) complex, Tp*Ni(κ(3)-BH(4)) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate anion), which has an S = 1 spin ground state, was studied by high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy as a solid powder at low temperature, by UV-vis-NIR spectroscopy in the solid state and in solution at room temperature, and by paramagnetic (11)B NMR. HFEPR provided its spin Hamiltonian parameters: D = 1.91(1) cm(-1), E = 0.285(8) cm(-1), g = [2.170(4), 2.161(3), 2.133(3)]. Similar, but not identical parameters were obtained for its borodeuteride analogue. The previously unreported complex, Tp*Zn(κ(2)-BH(4)), was prepared, and IR and NMR spectroscopy allowed its comparison with analogous closed shell borohydride complexes. Ligand-field theory was used to model the electronic transitions in the Ni(II) complex successfully, although it was less successful at reproducing the zero-field splitting (zfs) parameters. Advanced computational methods, both density functional theory (DFT) and ab initio wave function based approaches, were applied to these Tp*MBH(4) complexes to better understand the interaction between these metals and borohydride ion. DFT successfully reproduced bonding geometries and vibrational behavior of the complexes, although it was less successful for the spin Hamiltonian parameters of the open shell Ni(II) complex. These were instead best described using ab initio methods. The origin of the zfs in Tp*Ni(κ(3)-BH(4)) is described and shows that the relatively small magnitude of D results from several spin-orbit coupling (SOC) interactions of large magnitude, but with opposite sign. Spin-spin coupling (SSC) is also shown to be significant, a point that is not always appreciated in transition metal complexes. Overall, a picture of bonding and electronic structure in open and closed shell late transition metal borohydrides is provided, which has implications for the use of these complexes in catalysis and

  2. Carbon supported Cu-Pd nanoparticles as anode catalyst for direct borohydride-hydrogen peroxide fuel cells

    International Nuclear Information System (INIS)

    Carbon supported Cu-Pd bimetallic nanoparticles were prepared by a successive reduction method in aqueous solution and used as anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronopotentiometry (CP), linear sweep voltammetry (LSV) and fuel cell test. The results show that the size of the crystallite is around 12.5 nm, the Cu1Pd1/C catalyst presents the highest catalytic activity among all the resultant catalysts, and the DBHFC using Cu1Pd1/C as anode catalyst and Pt mesh (1 cm × 1 cm) as cathode electrode obtains the maximum power density as high as 39.8 mW cm-2 at a discharge current density of 80.1 mA cm-2 at 20 °C

  3. In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites.

    Science.gov (United States)

    Miedema, Piter S; Ngene, Peter; van der Eerden, Ad M J; Sokaras, Dimosthenis; Weng, Tsu-Chien; Nordlund, Dennis; Au, Yuen S; de Groot, Frank M F

    2014-11-01

    Nanoconfined alkali metal borohydrides are promising materials for reversible hydrogen storage applications, but the characterization of hydrogen sorption in these materials is difficult. Here we show that with in situ X-ray Raman spectroscopy (XRS) we can track the relative amounts of intermediates and final products formed during de- and re-hydrogenation of nanoconfined lithium borohydride (LiBH4) and therefore we can possibly identify the de- and re-hydrogenation pathways. In the XRS of nanoconfined LiBH4 at different points in the de- and re-hydrogenation, we identified phases that lead to the conclusion that de- and re-hydrogenation pathways in nanoconfined LiBH4 are different from bulk LiBH4: intercalated lithium (LiCx), boron and lithium hydride were formed during de-hydrogenation, but as well Li2B12H12 was observed indicating that there is possibly some bulk LiBH4 present in the nanoconfined sample LiBH4-C as prepared. Surprisingly, XRS revealed that the de-hydrogenated products of the LiBH4-C nanocomposites can be partially rehydrogenated to about 90% of Li2B12H12 and 2-5% of LiBH4 at a mild condition of 1 bar H2 and 350 °C. This suggests that re-hydrogenation occurs via the formation of Li2B12H12. Our results show that XRS is an elegant technique that can be used for in and ex situ study of the hydrogen sorption properties of nanoconfined and bulk light-weight metal hydrides in energy storage applications. PMID:25231357

  4. Alkaline sodium borohydride gel as a hydrogen source for PEMFC or an energy carrier for NaBH 4-air battery

    Science.gov (United States)

    Liu, B. H.; Li, Z. P.; Chen, L. L.

    In this preliminary study, we tried to use sodium polyacrylate as the super absorbent polymer to form alkaline NaBH 4 gel and explored its possibilities for borohydride hydrolysis and borohydride electro-oxidation. It was found that the absorption capacity of sodium polyacrylate decreased with increasing NaBH 4 concentration. The formed gel was rather stable in the sealed vessel but tended to slowly decompose in open air. Hydrogen generation from the gel was carried out using CoCl 2 catalyst precursor solutions. Hydrogen generation rate from the alkaline NaBH 4 gel was found to be higher and impurities in hydrogen were less than that from the alkaline NaBH 4 solution. The NaBH 4 gel also successfully powered a NaBH 4-air battery.

  5. Alkaline sodium borohydride gel as a hydrogen source for PEMFC or an energy carrier for NaBH{sub 4}-air battery

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B.H. [Department of Materials and Engineering, Zhejiang University (China); Li, Z.P.; Chen, L.L. [Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China)

    2008-05-15

    In this preliminary study, we tried to use sodium polyacrylate as the super absorbent polymer to form alkaline NaBH{sub 4} gel and explored its possibilities for borohydride hydrolysis and borohydride electro-oxidation. It was found that the absorption capacity of sodium polyacrylate decreased with increasing NaBH{sub 4} concentration. The formed gel was rather stable in the sealed vessel but tended to slowly decompose in open air. Hydrogen generation from the gel was carried out using CoCl{sub 2} catalyst precursor solutions. Hydrogen generation rate from the alkaline NaBH{sub 4} gel was found to be higher and impurities in hydrogen were less than that from the alkaline NaBH{sub 4} solution. The NaBH{sub 4} gel also successfully powered a NaBH{sub 4}-air battery. (author)

  6. The affects of membrane on the cell performance when using alkaline borohydride-hydrazine solutions as the fuel

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Haiying; Liu, Zixuan; Guo, Yanfeng; Li, Zhoupeng [Department of Chemical and Bio-chemical Engineering, Zhejiang University, Hangzhou 310027 (China)

    2010-04-15

    The cell performance and the polarization behavior of the fuel cell using alkaline NaBH{sub 4}-N{sub 2}H{sub 4} solutions as the fuel were investigated. It was found that the use of different membrane: anion exchange membrane (AEM) or cation exchange membrane (CEM) would influence the cell performance and cathode polarization behavior. The direct borohydride fuel cell (DBFC) using CEM gave a higher power density than that using AEM, but the direct hydrazine fuel cell (DHFC) using CEM gave a lower power density compared with the DHFC using AEM. In the DBFCs using CEM, N{sub 2}H{sub 4} addition in alkaline NaBH{sub 4} solution improved the cell performance but it did not make any difference when adding more N{sub 2}H{sub 4}. On the other hand, in the DBFCs using AEM, cell performance was improved with increasing the amount of N{sub 2}H{sub 4} in the anolyte. (author)

  7. Investigation of platinum and palladium as potential anodic catalysts for direct borohydride and ammonia borane fuel cells

    Science.gov (United States)

    Olu, Pierre-Yves; Deschamps, Fabien; Caldarella, Giuseppe; Chatenet, Marian; Job, Nathalie

    2015-11-01

    Platinum and palladium are investigated as anodic catalysts for direct borohydride and direct ammonia borane fuel cells (DBFC and DABFC). Half-cell characterizations performed at 25 °C using NH3BH3 or NaBH4 alkaline electrolytes demonstrate the lowest open-circuit potential and highest electrocatalytic activity for the NH3BH3 alkaline electrolyte for Pd and Pt rotating disk electrodes, respectively. Voltammograms performed in fuel cell configuration at 25 °C confirm this trend: the highest open circuit voltage (1.05 V) and peak power density (181 mW·cm-2) are monitored for DABFC using Pd/C and Pt/C anodes, respectively. Increasing the temperature heightens the peak power density (that reaches 420 mW·cm-2 at 60 °C for DBFC using Pt/C anodes), but strongly generates gas from the fuel hydrolysis, hindering the overall fuel cells performances. The anode texture strongly influences the fuel cell performances, highlighting: (i) that an open anode texture is required to efficiently circulate the anolyte and (ii) the difficulty to compare potential anodic catalysts characterized using different fuel cell setups within the literature. Furthermore, TEM imaging of Pt/C and Pd/C catalysts prior/post DBFC and DABFC operation shows fast degradation of the carbon-supported nanoparticles.

  8. Hydrogen generation and storage system using sodium borohydride at high pressures for operation of a 100 W-scale PMF stack

    OpenAIRE

    M.J.F. Ferreira; Rangel, C. M.; Pinto, A. M. F. R.

    2008-01-01

    A study is reported on the generation and storage of hydrogen from sodium borohydride (NaBH4) solutions in batch reactors, under pressures up to 4 MPa, in the presence of an improved and reused non-noble nickel-based powered catalyst. It follows references [1-10]. The first two purposes of the present work were to study the influence of the solution medium in the volume of hydrogen generated by hydrolysis of NaBH4, with a specific interest in: (1) comparing the performance of water and viscou...

  9. The mechanism of unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to 1,2,3,4-tetrahydrofuro[3,4-b]-pyridin-5(7H)-one with sodium borohydride

    Institute of Scientific and Technical Information of China (English)

    Yan Bo Tang; Qing Jian Zhang; De Quan Yu

    2012-01-01

    An unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to 1,2,3,4-tetrahydrofuro[3,4-b]pyridin-5(7H)-one with sodium borohydride in ethanol and tetrahydrofuran,respectively,is described,a hypothetic mechanism for the unusual reductive product is proposed.

  10. Structural analysis of some bis-(8-isopropyl-isoquinolinium) derivatives reveals a preferential folded conformation leading to a stereoselective attack by sodium borohydride

    Science.gov (United States)

    Dilly, Sébastien; Badarau, Eduard; Dufour, Fabien; Nistor, Iolanda; Hubert, Philippe; Seutin, Vincent; Wouters, Johan; Liégeois, Jean-François

    2014-09-01

    Reduction of symmetrical bis-isoquinolinium derivatives with sodium borohydride generates normally a mixture of three 1,2,3,4-tetrahydroisoquinoline stereoisomers. In a series of 8-isopropyl analogues, chiral resolution failed for the analogues with propyl and m-xylyl linkers since two and one peaks respectively were detected by HPLC. Further analysis by MS and CD of both peaks of the propyl analogue revealed that each peak corresponds to an enantiomer. Conformational analysis and X-ray cristallography showed a folded conformation of the propyl and m-xylyl analogues responsible for the observed stereoselectivity following the reduction step. Additional 1H NMR investigations confirm structural features detected by theoretical analysis.

  11. Use of a nickel-boride-silica nanocomposite catalyst prepared by in-situ reduction for hydrogen production from hydrolysis of sodium borohydride

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yingbo; Kim, Hern [Department of Environmental Engineering and Biotechnology, Myongji University, San 38-2 Namdong, Yongin, Kyonggi-do 449-728 (Korea)

    2008-10-15

    Hydrogen was produced by hydrolysis of sodium borohydride (NaBH{sub 4}) using nickel-boride-silica nanocomposite catalyst. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDX). The Ni-B-silica nanocomposite catalyst was found to consist of amorphous Ni-B nanoparticles attached to the surface of amine-modified silica nanosphere. The kinetics of hydrolysis of NaBH{sub 4} by Ni-B-silica composite catalyst was investigated. The effects of temperature, NaBH{sub 4} concentration, and catalyst concentration on hydrogen generation were also investigated. A rate of hydrogen generation as high as 1916 ml H{sub 2}/min/g Ni was achieved by catalytic hydrolysis of NaBH{sub 4}. The stability of the composite catalyst was also explored. (author)

  12. Surface-enhanced Raman scattering study of riboflavin on borohydride-reduced silver colloids: Dependence of concentration, halide anions and pH values

    Science.gov (United States)

    Liu, Fangfang; Gu, Huaimin; Lin, Yue; Qi, Yajing; Dong, Xiao; Gao, Junxiang; Cai, Tiantian

    2012-01-01

    The influences of concentration, halide anions and pH on the surface-enhanced Raman scattering (SERS) of riboflavin adsorbed on borohydride-reduced silver colloids were studied. The optimum concentration for the SERS of riboflavin is 10 -6 mol/L while the SERS enhancement varies for different modes. The addition of 0.2 mol/L halide (NaCl, NaBr, and NaI) aqueous solutions, leads to a general decrease of the SERS intensity and a change of spectral profile of riboflavin excited at 514.5 nm. Riboflavin interacts with the silver surface possibly through the C dbnd O and N-H modes of the uracil ring. The SERS spectra of riboflavin were recorded in the 3.4-11.6 pH range. By analyzing several SERS marker bands, the protonated, deprotonated or the coexistence of both molecular species adsorbed on the colloidal silver particles was proved.

  13. Preparation and characterization of PtRu/C, PtBi/C, PtRuBi/C electrocatalysts for direct electro-oxidation of ethanol in PEM fuels cells using the method of reduction by sodium borohydride

    International Nuclear Information System (INIS)

    Pt/C, PtBi/C, PtRu/C and PtRuBi/C electrocatalysts were prepared by a borohydride reduction methodology and tested for ethanol oxidation. This methodology consists in mix a solution with sodium hydroxide and sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. It was studied the addition method of borohydride (drop by drop addition or rapid addition). The obtained electrocatalysts were characterized by energy dispersive X ray spectroscopy (EDX), thermogravimetric analysis (TGA), X ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry. The ethanol electro-oxidation was studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were tested in real conditions of operation by unit cell tests. The stability of PtRuBi/C electrocatalysts was evaluated by cyclic voltammetry, chronoamperometry using the ultra-thin porous coating technique and ring-disk electrode. The PtRuBi/C electro catalyst apparently presented a good performance for ethanol electro-oxidation but experimental evidences showed accentuated bismuth dissolution. (author)

  14. 活化硼氢化钠在有机合成中的应用%The Applications of the Activated Sodium Borohydride in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    戴利

    2012-01-01

    介绍了有机合成反应中NaBH4与添加剂共同作用的反应,其中包括烯烃和炔烃的还原,羧酸的还原,氨基酸及其衍生物的还原,羧酸酯的还原,酰胺的还原,腈基的还原,酰氯的还原,硝基化合物的还原,醛酮的还原等。与LiAIH4的还原相比较,其反应条件更温和,反应过程更安全、易操控、易放大。%Introduced the applications of the activated sodium borohydride . It concluded reduction of alkene, alkyne, carboxylic acid, carboxylic acid ester, amide, nitrile group, acyl chloride, nitro group, aldehydes, ketones, amino acids as well as their derivatives. Comparing to the reduction of lithium aluminum hydride, it had milder reaction conditions, more secure reaction process and it was more easily controlled and amplified.

  15. Experimental study on the formation and growth of electroless nickel-boron coatings from borohydride-reduced bath on mild steel

    Energy Technology Data Exchange (ETDEWEB)

    Vitry, Veronique, E-mail: veronique.vitry@umons.ac.be [Service de Metallurgie, Universite de Mons, Rue de l' Epargne 56, 7000 Mons (Belgium); Sens, Adeline [Service de Metallurgie, Universite de Mons, Rue de l' Epargne 56, 7000 Mons (Belgium); Kanta, Abdoul-Fatah [Service de Sciences des Materiaux, Universite de Mons, Rue de l' Epargne 56, 7000 Mons (Belgium); Delaunois, Fabienne [Service de Metallurgie, Universite de Mons, Rue de l' Epargne 56, 7000 Mons (Belgium)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Initiation mechanism of electroless Ni-B on St-37 steel has been identified. Black-Right-Pointing-Pointer Different phases of the plating process were observed and identified. Black-Right-Pointing-Pointer Influence of chemical heterogeneity on coating morphology was revealed. Black-Right-Pointing-Pointer Batch replenishment of the plating bath induces new germination phase. - Abstract: Quality and homogeneity of electroless nickel-boron coatings are very important for applications in corrosion and electronics and are completely dependent on the formation of the deposit. The growth and formation process of electroless nickel-boron was investigated by immersing mild steel (St-37) samples in an un-replenished bath for various periods of time (from 5 s to 1 h). The coatings obtained at the different stages of the process were then characterized: thickness was measured by SEM, morphology was observed, weight gain was recorded and top composition of the coatings was obtained from XPS. Three main phases were identified during the coating formation and links between plating time, instantaneous deposition rate, chemistry of last formed deposit and morphology were established. The mechanism for initial deposition on steel substrate for borohydride-reduced electroless nickel bath was also observed. Those results were confronted with chemistry evolution in the unreplenished plating bath during the process. This allowed getting insight about phenomena occurring in the plating bath and their influence on coating formation.

  16. Synthesis and application of CeO2–NiO loaded TiO2 nanofiber as novel catalyst for hydrogen production from sodium borohydride hydrolysis

    International Nuclear Information System (INIS)

    A simple electrospinning technique was used to fabricate cerium–nickel loaded titanium nanofibers for efficient use in catalytic applications for hydrogen production. The prepared nanofibers were characterized by the SEM (scanning electron microscopy), EDX (energy dispersive X-ray spectrometer), FTIR (fourier transform infrared spectroscopy), XRD (X-ray diffraction), BET (Brunauer–Emmett–Teller) technique and TEM (transmission electron microscopy). The SEM and TEM analyses showed that fabricated nanofibers were defect-free and had well deposition of cerium and nickel. The BET analysis concluded that cerium–nickel loaded titanium oxide nanofiber showed greater surface area and high porosity than other nanofiber compositions. The experimental results showed that addition of cerium with nickel enhanced the catalytic activity significantly, but excessive cerium-loading had a negative effect on sodium borohydride hydrolysis. Activation energy of cerium–nickel loaded titanium oxide nanofiber was comparatively lesser than nickel-loaded titanium oxide nanofiber. It was evident that cerium had a beneficial effect in the catalytic activity for hydrogen production. Furthermore, it is very convenient to recover the catalyst at the end of reactions; the solid catalyst left could be readily reused for the next consecutive cycles. - Highlights: • A simple electrospinning is used to allow uniform deposition of spherical CeO2 and NiO NPs on nanofiber based TiO2. • The prepared materials were characterized by SEM, EDX, TEM, XRD, BET and FT–IR analyses. • The presence of Ni with Ce has beneficial attributes on the catalyst performance by structural modifications. • In this study, 1:2 ratio of Ce/Ni was found to be the best for CeO2–NiO–TiO2 catalyst system. • The catalysts obtained show high catalytic activity and good stability to produce H2 with higher reusability

  17. XPS, TEM and SAD investigations of nanosized Co{sub x}B{sub y}H{sub z} particles obtained by two different borohydride methods

    Energy Technology Data Exchange (ETDEWEB)

    Krastev, V. [Bulgarian Acad. of Sci., Sofia (Bulgaria). Inst. of General and Inorg. Chem.; Stoycheva, M. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Lefterova, E. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Dragieva, I. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Stoynov, Z. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria)

    1996-07-01

    The nanosized Co{sub x}B{sub y}H{sub z} particles synthesised by the ``tea`` and ``antigravity`` methods using a borohydride reduction process have been subjected to structure and composition studies by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and selected area diffraction (SAD). The amounts of the elements Co, B, O{sub 2}, H{sub 2} and C as mean volume values, and surface values for the as-prepared particles, as well as after Ar{sup +} etching to a depth of about 15 nm and 30 nm from the initial particle surface, are determined. About 1.5 atoms of cobalt per atom of boron correspond to samples obtained by the ``antigravity`` method. The binding energy (BE) of 1s electrons of boron atoms has only one value. These particles are angular and are in the typical nanocrystalline state. In the case of samples prepared by the ``tea`` method, two atoms of cobalt per atom of boron are found. The presence of two kinds of BE (B{sup I} and B{sup II}) of 1s electrons of boron atoms in the particles obtained by the ``tea`` method is observed and almost equal amounts of these two states are established in the spectrum. The particles` shape and structure are typical of the amorphous state. The fact that there is one peak when the ``antigravity`` method is applied, in contrast to the two peaks with the ``tea`` method indicates the presence of a metal amorphous state in the latter case. (orig.)

  18. Hydrogen storage properties of rare earth (RE) borohydrides (RE = La, Er) in composite mixtures with LiBH{sub 4} and LiH

    Energy Technology Data Exchange (ETDEWEB)

    Frommen, Christoph; Heere, Michael [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027 Kjeller (Norway); Riktor, Marit D. [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027 Kjeller (Norway); SINTEF Materials and Chemistry, Forskningsveien 1, NO-0314 Oslo (Norway); Sørby, Magnus H. [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027 Kjeller (Norway); Hauback, Bjørn C., E-mail: bjorn.hauback@ife.no [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027 Kjeller (Norway)

    2015-10-05

    Highlights: • 6LiBH{sub 4}–RECl{sub 3}–3LiH composites (RE = La, Er) studied for the first time. • Drastically reduced decomposition temperature (300 {sup o}C) compared to LiBH{sub 4} (>400 °C). • Partial reversibility for 6LiBH{sub 4}–LaCl{sub 3}–3LiH: (19% at 340 °C, 10 MPa). • Excellent reversibility for 6LiBH{sub 4}–ErCl{sub 3}–3LiH: (80% at 340 °C, 10 MPa). • Reversibility comparable to that obtained for pure LiBH{sub 4} (76% at 600 °C and 15.5 MPa). - Abstract: Mixtures of 6LiBH{sub 4}–RECl{sub 3}–3LiH (RE = La, Er) have been produced by mechanochemical milling and their structure, thermal decomposition and reversibility have been studied. Hydrogen desorption starts around 300 °C in both composites. Heating to 400 °C yields LaB{sub 6}, ErB{sub 4} and REH{sub 2+δ} as major decomposition products. LiBH{sub 4} is destabilized by REH{sub 2+δ} formed through decomposition of the parent borohydrides LiLa(BH{sub 4}){sub 3}Cl and Er(BH{sub 4}){sub 3}, respectively, and its hydrogen release temperature is reduced by 100 °C as compared to pure ball-milled LiBH{sub 4}. The lanthanum-containing composite releases 4.2 wt.% H between 300 and 350 °C and shows a limited reversibility of ∼20% (340 °C, 10 MPa) probably due to hydrogen uptake by some amorphous boron-containing phases. For 6LiBH{sub 4}–ErCl{sub 3}–3LiH about 3 wt.% H is evolved up to 400 °C. Desorption against 0.5 MPa backpressure results in an increased reversibility (∼80%) as compared to vacuum (∼66%). Rehydrogenation (340 °C, 10 MPa) shows the formation of ErH{sub 3} and LiBH{sub 4} at drastically reduced conditions compared to pure LiBH{sub 4} (>400 °C, >10 MPa)

  19. Rotational disorder in lithium borohydride

    International Nuclear Information System (INIS)

    LiBH4 has been discussed as a promising hydrogen storage material and as a solid-state electrolyte in lithium-ion batteries. It contains 18.5 wt% hydrogen and undergoes a structural phase transition at 381 K which is associated with a large increase in rotational disorder of the [BH4]- anion and the increase of [Li]+ conductivity by 3 orders of magnitude. We investigated the [BH4]- anion dynamic in bulk LiBH4, in LiBH4-LiI solid solutions and in nano-confined LiBH4 by quasielastic neutron scattering, complemented by DFT calculations. In all cases the H-dynamics is dominated by thermally activated rotational jumps of the [BH4]- anion in the tera hertz range. The addition of LiI as well as nano-confinement favours the disordered high temperature phase and lowers the phase transition below room temperatures. The results are discussed on the basis of first principles calculations and in relation to ionic conductivity of [Li]+. (authors)

  20. Rotational disorder in lithium borohydride

    Directory of Open Access Journals (Sweden)

    Remhof Arndt

    2015-01-01

    Full Text Available LiBH4 has been discussed as a promising hydrogen storage material and as a solid-state electrolyte in lithium-ion batteries. It contains 18.5 wt% hydrogen and undergoes a structural phase transition at 381 K which is associated with a large increase in rotational disorder of the [BH4]− anion and the increase of [Li]+ conductivity by three orders of magnitude. We investigated the [BH4]− anion dynamic in bulk LiBH4, in LiBH4-LiI solid solutions and in nano-confined LiBH4 by quasielastic neutron scattering, complemented by DFT calculations. In all cases the H-dynamics is dominated by thermally activated rotational jumps of the [BH4]− anion in the terahertz range. The addition of LiI as well as nano-confinement favours the disordered high temperature phase and lowers the phase transition below room temperatures. The results are discussed on the basis of first principles calculations and in relation to ionic conductivity of [Li]+.

  1. Synthesis of a tritium labeled tetrafluoro-substituted aryl azide photoaffinity labeling agent for chloride channels. Application of [3H]-sodium borohydride-cobalt chloride to tritium labeling

    International Nuclear Information System (INIS)

    5-Nitro-2-[N-3-(4-azido-2,3,5,6-tetrafluorophenyl)-propylamino]-benzoic acid (FAzNPPB), a photoaffinity analog of the potent epithelial chloride channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) has been prepared in five steps from commercially available 4-amino-2,3,5,6-tetrafluorobenzonitrile. The main feature of this synthesis was the use of NaBH4-CoCl2 to convert an aryl-substituted alkenyl nitrile precursor to the corresponding alkyl amine. The feasibility of this approach and the stoichiometry were developed by model work with cinnamonitrile. Using sodium borotritide-cobalt chloride, [3H]-FAzNPPB (specific activity 13.9 mCi/mmol, radiochemical purity >99%) was prepared in three steps from (E)-4-amino-2,3,5,6-tetrafluoro-cinnamonitrile. [3H]-Sodium borohydride, cobalt chloride, azide, photaffinity, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB). (author)

  2. Immobilization of CoCl2 (cobalt chloride) on PAN (polyacrylonitrile) composite nanofiber mesh filled with carbon nanotubes for hydrogen production from hydrolysis of NaBH4 (sodium borohydride)

    International Nuclear Information System (INIS)

    Composite nanofiber sheets containing multiwalled carbon nanotubes and cobalt chloride dispersed in PAN (polyacrylonitrile) were produced by an electrospinning technique. The synthesized PAN/CoCl2/CNTs composite nanofiber was used as the catalyst for hydrogen production from the hydrolysis of sodium borohydride. FT-IR characterization showed that the pretreated CNTs possess different organic functional groups which help improve the compatibility between CNTs and PAN organic polymer. SEM (scanning electron microscopy), TEM (transmission electron microscopy) and EDX (energy-dispersive X-ray technique) were used to characterize the composite nanofiber and it was found that CNTs can be coaxially dispersed into the PAN nanofiber. During the hydrolysis of NaBH4, this PAN/CoCl2/CNTs composite nanofiber exhibited higher catalytic activity compared to the composite without CNTs doping. Kinetic analysis of NaBH4 hydrolysis shows that the reaction of NaBH4 hydrolysis based on this catalyst can be ascribed to the first-order reaction and the activation energy of the catalyst was approximately 52.857 kJ/mol. Meanwhile, the composite nanofiber catalyst shows excellent stability and reusability in the recycling experiment. - Highlights: • Composite nanofiber sheets were prepared via electrospinning. • PAN (polyacrylonitrile)/CoCl2 (cobalt chloride)/CNTs (carbon nanotubes) nanofiber was used as the catalyst for hydrogen production. • CNTs can be coaxially dispersed into the PAN nanofiber. • PAN/CoCl2/CNTs composite nanofiber exhibited higher catalytic activity. • The composite nanofiber catalyst shows excellent stability and reusability

  3. NaBH4 (sodium borohydride) hydrogen generator with a volume-exchange fuel tank for small unmanned aerial vehicles powered by a PEM (proton exchange membrane) fuel cell

    International Nuclear Information System (INIS)

    A proton exchange membrane fuel cell system integrated with a NaBH4 (sodium borohydride) hydrogen generator was developed for small UAVs (unmanned aerial vehicles). The hydrogen generator was composed of a catalytic reactor, liquid pump and volume-exchange fuel tank, where the fuel and spent fuel exchange the volume within a single fuel tank. Co–B catalyst supported on a porous ceramic material was used to generate hydrogen from the NaBH4 solution. Considering the power consumption according to the mission profile of a UAV, the power output of the fuel cell and auxiliary battery was distributed passively as an electrical load. A blended wing-body was selected considering the fuel efficiency and carrying capability of fuel cell components. First, the fuel cell stack and hydrogen generator were evaluated under the operating conditions, and integrated into the airframe. The ground test of the complete fuel cell UAV was performed under a range of load conditions. Finally, the fuel cell powered flight test was made for 1 h. The volume-exchange fuel tank minimized the fuel sloshing and the change in center of gravity due to fuel consumption during the flight, so that much stable operation of the fuel cell system was validated at different flight modes. - Highlights: • PEMFC system with a NaBH4 hydrogen source was developed for small UAVs. • Volume-exchange fuel tank was used to reduce the size of the fuel cell system. • Passive power management was used for a stable power output during the flight. • BWB UAV was selected by taking the fuel cell integration into consideration. • Stable operation of the fuel cell system was verified from the flight test

  4. 硼氢化钠制氢技术在质子交换膜燃料电池中的研究进展%Recent advances in the study of sodium borohydride hydrolysis for pure hydrogen supply to PEM fuel cell

    Institute of Scientific and Technical Information of China (English)

    王玉晓

    2009-01-01

    硼氢化钠储氢量高达10.6%,安全、无爆炸危险,携带和运输方便;供氢系统设备简单,启动速度快,产氢速度可调,因此是一个非常良好的氢载体,是为质子交换膜燃料电池供氢的理想储氢介质.硼氢化钠供氢系统也已逐步应用于质子交换膜燃料电池电源中.介绍了这种制氢方式的几项关键技术:硼氢化钠水解制氢催化剂、硼氢化钠制氢反应器、氢气净化系统等在质子交换膜燃料电池中的研究进展,并指出了今后的研究发展方向.%Sodium borohydride contains hydrogen as high as 10.6%, and it is safe, no fire and explosion danger, and portable. This hydrogen supply system has the features of simple structure, fast starting, and adjustable hydrogen production speed. Therefore, sodium borohydride is a very promising hydrogen carrier and a perfect medium for pure hydrogen supply to proton exchange membrane fuel cell (PEMFC). In fact, the hydrolysis of sodium borohydride for hydrogen supply to PEMFC is in the way to real application. This review summarizes the recent advances in this hydrogen generation system including catalysts, reactors and purification methods, and the direction for sequent research is also discussed.

  5. Preparation and characterization of PtRu/C, PtBi/C, PtRuBi/C electrocatalysts for direct electro-oxidation of ethanol in PEM fuels cells using the method of reduction by sodium borohydride; Preparacao e caracterizacao de eletrocatalisadores PtRu/C, PtBi/C, PtRuBi/C para eletro-oxidacao direta de etanol em celulas a combustivel tipo PEM utilizando a metodologia da reducao via borohidreto de sodio

    Energy Technology Data Exchange (ETDEWEB)

    Brandalise, Michele

    2010-07-01

    Pt/C, PtBi/C, PtRu/C and PtRuBi/C electrocatalysts were prepared by a borohydride reduction methodology and tested for ethanol oxidation. This methodology consists in mix a solution with sodium hydroxide and sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. It was studied the addition method of borohydride (drop by drop addition or rapid addition). The obtained electrocatalysts were characterized by energy dispersive X ray spectroscopy (EDX), thermogravimetric analysis (TGA), X ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry. The ethanol electro-oxidation was studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were tested in real conditions of operation by unit cell tests. The stability of PtRuBi/C electrocatalysts was evaluated by cyclic voltammetry, chronoamperometry using the ultra-thin porous coating technique and ring-disk electrode. The PtRuBi/C electro catalyst apparently presented a good performance for ethanol electro-oxidation but experimental evidences showed accentuated bismuth dissolution. (author)

  6. Structural phase transitions and adduct release in calcium borohydride

    Energy Technology Data Exchange (ETDEWEB)

    Paolone, A.; Palumbo, O.; Rispoli, P.; Miriametro, A.; Cantelli, R.; Luedtke, A.; Rönnebro, E.; Chandra, D.

    2011-09-01

    Ca(BH4)2 compounds were investigated above room temperature by anelastic spectroscopy (AS) and concomitant measurements of thermogravimetry and mass spectrometry (TGA/MS). Both AS and TGA/MS indicate that even after a thermal treatment at 125 °C for 20 h, a non-negligible residual of THF adduct is still present in the sample, which can be removed on a subsequent thermal treatment at temperatures lower than 250 °C. Above 250 °C dehydrogenation takes place. Moreover, AS sensitively detects the occurrence of the α → α’ structural phase transition around 180 °C, and the α’ → β transformation, which is completed around 330 °C. Finally, we also show that both transitions are irreversible and are not accompanied by a latent heat.

  7. Destabilized and catalyzed borohydride for reversible hydrogen storage

    Science.gov (United States)

    Mohtadi, Rana F.; Nakamura, Kenji; Au, Ming; Zidan, Ragaiy

    2012-01-31

    A process of forming a hydrogen storage material, including the steps of: providing a first material of the formula M(BH.sub.4).sub.X, where M is an alkali metal or an alkali earth metal, providing a second material selected from M(AlH.sub.4).sub.x, a mixture of M(AlH.sub.4).sub.x and MCl.sub.x, a mixture of MCl.sub.x and Al, a mixture of MCl.sub.x and AlH.sub.3, a mixture of MH.sub.x and Al, Al, and AlH.sub.3. The first and second materials are combined at an elevated temperature and at an elevated hydrogen pressure for a time period forming a third material having a lower hydrogen release temperature than the first material and a higher hydrogen gravimetric density than the second material.

  8. Nanoconfined Alkali-metal borohydrides for Reversible Hydrogen Storage

    NARCIS (Netherlands)

    Ngene, P.

    2012-01-01

    Hydrogen has been identified as a promising energy carrier. Its combustion is not associated with pollution when generated from renewable energy sources like solar and wind. The large-scale use of hydrogen for intermittent energy storage and as a fuel for cars can contribute to the realization of a

  9. Oxidation/Sodium Borohydride Reduction Protocol in One Pot

    Directory of Open Access Journals (Sweden)

    Silvano Cruz-Gregorio

    2005-01-01

    Full Text Available La reacción de oxidación de Swern-reducción con borohidruro de sodio en un solo paso de los derivados de 1,2-O-isopropilidenofuranosa con configuración D-gluco o D-xilo, producen sus estereoisómeros correspondientes, los cuales provienen de la inversión estereoselectiva del C-3. Este método es una adaptación al procedimiento tradicional de oxidación de Swern, en donde al término de la reacción se adiciona una mezcla de H2O/EtOH (1:4 a -60 ºC, en la cual se disuelve NaBH4. Así, la inversión de la configuración del C-3 en los derivados de 1,2-O-isopropylidenofuranosa se logra en rendimientos hasta del 98%.

  10. Borohydride electro-oxidation in a molten alkali hydroxide eutectic mixture and a novel borohydride-periodate battery

    Science.gov (United States)

    Wang, Andrew; Gyenge, Előd L.

    2015-05-01

    The electrochemical oxidation of BH4- in a molten NaOH-KOH eutectic mixture (0.515:0.485 mole fractions), is investigated for the first time by cyclic voltammetry and electrochemical impedance spectroscopy. Anodically oxidized Ni is electrocatalytically more active than Pt for BH4- oxidation in the molten alkali electrolyte as shown by the more than three times higher exchange current density (i.e. 15.8 mA cm-2 vs. 4.6 mA cm-2 at 185 °C). Next the proof-of-concept for a novel BH4-/IO4- molten alkali electrolyte battery is presented. Using oxidized Ni mesh anode and Pt mesh cathode a maximum power density of 63 mW cm-2 is achieved at 185 °C.

  11. Hydrogen rotational and translational diffusion in calcium borohydride from quasielastic neutron scattering and DFT

    DEFF Research Database (Denmark)

    Blanchard, Didier; Riktor, M.D.; Maronsson, Jon Bergmann;

    2010-01-01

    .10 eV) and mean residence times are comparable with those obtained from DFT calculations. Long-range diffusion events, with an energy barrier of EaD = 0.12 eV and an effective jump length of 2.5 Å were observed at 224 and 260 K. Three vacancy-mediated diffusion events, H jumps between two neighboring...... different time scales in combination with density functional theory (DFT) calculations. Two thermally activated reorientational motions were observed, around the 2-fold (C2) and 3-fold (C3) axes of the BH4− units, at temperature from 95 to 280K. The experimental energy barriers (EaC2 = 0.14 eV and EaC3 = 0...... BH4−, and diffusion of BH4− and BH3 groups were calculated and finally discarded because of their very high formation energies and diffusion barriers. Three interstitial diffusion processes (H, H2, and H2O) were also calculated. The H interstitial was found to be highly unstable, whereas the H2...

  12. Dehydrogenation in lithium borohydride/conventional metal hydride composite based on a mutual catalysis

    DEFF Research Database (Denmark)

    Yu, X.B.; Shi, Qing; Vegge, Tejs;

    2009-01-01

    The dehydrogenation of LiBH4 ball-milled with hydrogenated 40Ti–15Mn–15Cr–30V alloy was investigated. It was found that there is a mutual catalysis between the two hydrides, lowering the temperature of hydrogen release from both hydrides. In the case of 1h milled LiBH4/40Ti–15Mn–15Cr–30V with a...

  13. Recent Advances in the Use of Sodium Borohydride as a Solid State Hydrogen Store

    Directory of Open Access Journals (Sweden)

    Jianfeng Mao

    2015-01-01

    Full Text Available The development of new practical hydrogen storage materials with high volumetric and gravimetric hydrogen densities is necessary to implement fuel cell technology for both mobile and stationary applications. NaBH4, owing to its low cost and high hydrogen density (10.6 wt%, has received extensive attention as a promising hydrogen storage medium. However, its practical use is hampered by its high thermodynamic stability and slow hydrogen exchange kinetics. Recent developments have been made in promoting H2 release and tuning the thermodynamics of the thermal decomposition of solid NaBH4. These conceptual advances offer a positive outlook for using NaBH4-based materials as viable hydrogen storage carriers for mobile applications. This review summarizes contemporary progress in this field with a focus on the fundamental dehydrogenation and rehydrogenation pathways and properties and on material design strategies towards improved kinetics and thermodynamics such as catalytic doping, nano-engineering, additive destabilization and chemical modification.

  14. Preparation of Silver-Montmorillonite Nanocomposites by Reduction with Formaldehyde and Borohydride

    Czech Academy of Sciences Publication Activity Database

    Praus, P.; Turicová, M.; Klementová, Mariana

    2009-01-01

    Roč. 20, č. 7 (2009), s. 1351-1357. ISSN 0103-5053 Institutional research plan: CEZ:AV0Z40320502 Keywords : silver * nanocomposites * montmorillonite * reduction Subject RIV: CA - Inorganic Chemistry Impact factor: 1.458, year: 2009

  15. Crystal Structure of a Lightweight Borohydride from Submicrometer Crystallites by Precession Electron Diffraction

    OpenAIRE

    Hadermann, Joke; Abakumov, Artem; Rompaey, van, R.S.A.R.; Perkisas, Tyche; Filinchuk, Yaroslav; Tendeloo, van, G.

    2012-01-01

    Abstract: We demonstrate that precession electron diffraction at low-dose conditions can be successfully applied for structure analysis of extremely electron-beam-sensitive materials. Using LiBH4 as a test material, complete structural information, including the location of the H atoms, was obtained from submicrometer-sized crystallites. This demonstrates for the first time that, where conventional transmission electron microscopy techniques fail, quantitative precession electron diffraction ...

  16. Crystal and molecular structure of calcium borohydride complexe with dimethyl ether of diethylene glycol

    International Nuclear Information System (INIS)

    All the main and supplementary types of patients' postures during roentgenological investigations of the skeleton and internal organs are systematized in the atlas. Special attention is paid to patients' posture at computerized tomography

  17. Stereoselectivity of sodium borohydride reduction of saturated steroidal ketones utilizing conditions of Luche reduction

    Czech Academy of Sciences Publication Activity Database

    Šťastná, Eva; Černý, Ivan; Pouzar, Vladimír; Chodounská, Hana

    2010-01-01

    Roč. 75, č. 10 (2010), s. 721-725. ISSN 0039-128X R&D Projects: GA ČR(CZ) GA203/08/1498; GA MŠk(CZ) LC06077 Institutional research plan: CEZ:AV0Z40550506 Keywords : steroid * synthesis * stereoselectivity Subject RIV: CC - Organic Chemistry Impact factor: 3.106, year: 2010

  18. Stereoselective sodium borohydride reductions of cyclopentanones: influence of ceric chloride on the stereochemistry of reaction

    International Nuclear Information System (INIS)

    In this paper we describe the reduction by Na BH4 of some cyclopentanones containing an oxygenated function at the side chain position β to the carbonyl group, both in the presence and in the absence of Ce CL3. Some suggestions for the rationalization of the results are discussed, considering the stereochemical course of the reactions. (author)

  19. Synthesis of rock-salt type lithium borohydride and its peculiar Li+ ion conduction properties

    Directory of Open Access Journals (Sweden)

    R. Miyazaki

    2014-05-01

    Full Text Available The high energy density and excellent cycle performance of lithium ion batteries makes them superior to all other secondary batteries and explains why they are widely used in portable devices. However, because organic liquid electrolytes have a higher operating voltage than aqueous solution, they are used in lithium ion batteries. This comes with the risk of fire due to their flammability. Solid electrolytes are being investigated to find an alternative to organic liquid. However, the nature of the solid-solid point contact at the interface between the electrolyte and electrode or between the electrolyte grains is such that high power density has proven difficult to attain. We develop a new method for the fabrication of a solid electrolyte using LiBH4, known for its super Li+ ion conduction without any grain boundary contribution. The modifications to the conduction pathway achieved by stabilizing the high pressure form of this material provided a new structure with some LiBH4, more suitable to the high rate condition. We synthesized the H.P. form of LiBH4 under ambient pressure by doping LiBH4 with the KI lattice by sintering. The formation of a KI - LiBH4 solid solution was confirmed both macroscopically and microscopically. The obtained sample was shown to be a pure Li+ conductor despite its small Li+ content. This conduction mechanism, where the light doping cation played a major role in ion conduction, was termed the “Parasitic Conduction Mechanism.” This mechanism made it possible to synthesize a new ion conductor and is expected to have enormous potential in the search for new battery materials.

  20. Quasielastic neutron scattering study of tetrahydroborate anion dynamical perturbations in sodium borohydride due to partial halide anion substitution

    Energy Technology Data Exchange (ETDEWEB)

    Verdal, Nina [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Udovic, Terrence J. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Rush, John J. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Skripov, Alexander V. [Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation)

    2015-10-05

    Highlights: • NaBH{sub 4}–NaX (X = Cl, I) solutions were made by ball-milling/annealing pure compounds. • BH{sub 4}{sup −} reorientational motions were studied by quasielastic neutron scattering. • Mobility increased from X = Cl to NaBH{sub 4} to X = I, consistent with expanding lattices. • Near 400 K, BH{sub 4}{sup −} favored cubic tumbling for X = Cl and tetrahedral tumbling for X = I. • Activation energies were in the range of 11–12 kJ mol{sup −1} for both compounds. - Abstract: Equimolar NaBH{sub 4}–NaX (X = Cl and I) solid solutions were synthesized to study, via quasielastic neutron scattering, the effect of partial halide anion substitution on the reorientational dynamics of tetrahydroborate (BH{sub 4}{sup −}) anions in NaBH{sub 4}. The BH{sub 4}{sup −} reorientational mobility increased in the order of NaBH{sub 4}–NaCl, NaBH{sub 4}, and NaBH{sub 4}–NaI, which corresponded with expanding face-centered-cubic lattices accommodating the respective increasing sizes of the Cl{sup −}, BH{sub 4}{sup −}, and I{sup −} anions. The BH{sub 4}{sup −} anions in NaBH{sub 4}–NaCl were found (at least above 400 K) to undergo ‘cubic’ tumbling motions with the four H atoms per anion visiting all eight corners of a cube, similar to what was previously observed for NaBH{sub 4}. In contrast, the BH{sub 4}{sup −} anions in NaBH{sub 4}–NaI were found to undergo something more akin to ‘tetrahedral’ tumbling motions, where the H atoms visit all four corners of a tetrahedron. Despite a noticeable softening of the BH{sub 4}{sup −} torsional energies with increasing lattice constant amongst NaBH{sub 4} and the two solid solutions, all three compounds exhibited similar activation energies for reorientation of about 11–12 kJ mol{sup −1}.

  1. High volumetric hydrogen density phases of magnesium borohydride at high-pressure: A first-principles study

    Institute of Scientific and Technical Information of China (English)

    Fan Jing; Bao Kuo; Duan De-Fang; Wang Lian-Cheng; Liu Bing-Bing; Cui Tian

    2012-01-01

    The previously proposed theoretical and experimental structures,bond characterization,and compressibility of Mg(BH4)2 in a pressure range from 0 to 10 GPa are studied by ab initio density-functional calculations.It is found that the ambient pressure phases of meta-stable I41/amd and unstable P-3ml proposed recently are extra stable and cannot decompose under high pressure.Enthalpy calculation indicates that the ground state of F222 structure proposed by Zhou et al.[2009 Phys.Rev.B 79 212102]will transfer to I41/amd at 0.7 GPa,and then to a P-3m1 structure at 6.3 GPa.The experimental P6122 structure (α-phase) transfers to I41/amd at 1.2 GPa.Furthermore,both I41/amd and P-3m1 can exist as high volumetric hydrogen density phases at low pressure.Their theoretical volumetric hydrogen densities reach 146.351 g H2/L and 134.028 g H2/L at ambient pressure,respectively.The calculated phonon dispersion curve shows that the I41/amd phase is dynamically stable in a pressure range from 0 to 4 GPa and the P-3ml phase is stable at pressures higher than 1 GPa.So the I41/amd phase may be synthesized under high pressure and retained to ambient pressure.Energy band structures show that they are both always ionic crystalline and insulating with a band-gap of about 5 eV in this pressure range.In addition,they each have an anisotropic compressibility.The c axis of these structures is easy to compress.Especially,the c axis and volume of P-3m1 phase are extraordinarily compressible,showing that compression along the c axis can increase the volumetric hydrogen content for both I41/amd and P-3m1 structures.

  2. First-principles study on copper-substituted lithium borohydride (Li1-xCux)BH4

    International Nuclear Information System (INIS)

    Our recent analysis using the first-principles calculations for LiBH4 [K. Miwa, N. Ohba, S. Towata, Y. Nakamori, S. Orimo, Phys. Rev. B 69 (2004) 245120], which is rather stable and desorbs hydrogen only at elevated temperatures, reveals that the charge compensation by Li+ cations is a key feature for the stability of the internal bonding [BH4]- anions. Considering this character, we have proposed the partial substitution of more electronegative elements for Li to lower the dehydriding temperature. The effect of the cation substitution is examined theoretically. We select copper as a substituent element, since the ionic radii of Cu+ and Li+ are almost the same but the electronegativity of Cu is larger than that of Li. Assuming the same crystal structure as orthorhombic LiBH4, the calculations on (Li1-xCux)BH4 are performed for x=0.25, 0.5, 0.75, and 1. It is confirmed that the heat of formation increases with increasing the Cu content x. The optimum x is predicted to be around x=0.3 for practical applications

  3. Quasielastic neutron scattering study of tetrahydroborate anion dynamical perturbations in sodium borohydride due to partial halide anion substitution

    International Nuclear Information System (INIS)

    Highlights: • NaBH4–NaX (X = Cl, I) solutions were made by ball-milling/annealing pure compounds. • BH4− reorientational motions were studied by quasielastic neutron scattering. • Mobility increased from X = Cl to NaBH4 to X = I, consistent with expanding lattices. • Near 400 K, BH4− favored cubic tumbling for X = Cl and tetrahedral tumbling for X = I. • Activation energies were in the range of 11–12 kJ mol−1 for both compounds. - Abstract: Equimolar NaBH4–NaX (X = Cl and I) solid solutions were synthesized to study, via quasielastic neutron scattering, the effect of partial halide anion substitution on the reorientational dynamics of tetrahydroborate (BH4−) anions in NaBH4. The BH4− reorientational mobility increased in the order of NaBH4–NaCl, NaBH4, and NaBH4–NaI, which corresponded with expanding face-centered-cubic lattices accommodating the respective increasing sizes of the Cl−, BH4−, and I− anions. The BH4− anions in NaBH4–NaCl were found (at least above 400 K) to undergo ‘cubic’ tumbling motions with the four H atoms per anion visiting all eight corners of a cube, similar to what was previously observed for NaBH4. In contrast, the BH4− anions in NaBH4–NaI were found to undergo something more akin to ‘tetrahedral’ tumbling motions, where the H atoms visit all four corners of a tetrahedron. Despite a noticeable softening of the BH4− torsional energies with increasing lattice constant amongst NaBH4 and the two solid solutions, all three compounds exhibited similar activation energies for reorientation of about 11–12 kJ mol−1

  4. Theoretical and experimental study on Mg(BH{sub 4}){sub 2}–Zn(BH{sub 4}){sub 2} mixed borohydrides

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, E. [Dipartimento di Chimica and NIS, Università di Torino, Via P. Giuria 7-9, I-10125 Torino (Italy); Kalantzopoulos, G.N. [Institute for Energy Technology, Department of Physics, P.O. Box 40, NO-2027 Kjeller (Norway); Vitillo, J.G.; Pinatel, E.; Civalleri, B. [Dipartimento di Chimica and NIS, Università di Torino, Via P. Giuria 7-9, I-10125 Torino (Italy); Deledda, S. [Institute for Energy Technology, Department of Physics, P.O. Box 40, NO-2027 Kjeller (Norway); Bordiga, S. [Dipartimento di Chimica and NIS, Università di Torino, Via P. Giuria 7-9, I-10125 Torino (Italy); Hauback, B.C. [Institute for Energy Technology, Department of Physics, P.O. Box 40, NO-2027 Kjeller (Norway); Baricco, M., E-mail: marcello.baricco@unito.it [Dipartimento di Chimica and NIS, Università di Torino, Via P. Giuria 7-9, I-10125 Torino (Italy)

    2013-12-15

    Highlights: •An ideal mixing behavior was predicted for Mg{sub (1−x)}Zn{sub x}(BH{sub 4}){sub 2} solid solutions. •A value of 30kJmol{sub H2}{sup -1} for the enthalpy of decomposition has been calculated for x = 0.2. •Samples have been synthesized ball milling Mg(BH{sub 4}){sub 2} and ZnCl{sub 2} in a molar ratio 1:0.7. •B{sub 2}H{sub 6} is released preventing the reversibility of hydrogen sorption. •Thermodynamic calculations supported experimental data. -- Abstract: After a screening of possible systems prone to give an enthalpy of decomposition close to 30kJmol{sub H2}{sup -1}, i.e. suitable for a dehydrogenation process close to room temperature and pressure, the Zn dissolution into Mg(BH{sub 4}){sub 2} has been investigated. The total energy of pure compounds and solid solutions has been computed by DFT calculations using the CRYSTAL09 code. To generate the Mg{sub (1−x)}Zn{sub x}(BH{sub 4}){sub 2} solid solution, α-phase of Mg(BH{sub 4}){sub 2} (space group P6{sub 1}22) has been considered, with a replacement of Mg{sup 2+} with Zn{sup 2+} ions, without lowering the symmetry of the crystalline structure. On the basis of DFT results, the enthalpy of decomposition has been estimated, considering MgH{sub 2}, Zn, α-B and H{sub 2} as products, and a value of 30kJmol{sub H2}{sup -1} has been calculated for x = 0.2. In order to verify the results of calculations, mixtures of Mg(BH{sub 4}){sub 2} and ZnCl{sub 2} with 1.0:0.7 ratio have been ball milled, both at room temperature and in cryo-conditions. Samples have been analyzed with a combination of experimental techniques (XRD, DSC, IR–ATR, TGA, TPD, PCI). The phase mixture obtained after the synthesis strongly depends on the milling conditions. For prolonged times, the formation of Zn and MgCl{sub 2} has been observed, suggesting the delivering of B-containing species during the milling. After heating, a hydrogen release, coupled with diborane delivering, has been observed for temperatures close to 100 °C, suggesting a significant decrease of the decomposition temperature with respect to pure Mg(BH{sub 4}){sub 2}. Theoretical and experimental results have been discussed on the basis of the possible reaction paths, as estimated from available thermodynamic databases.

  5. Reduction of N-Cyanomethyl Groups on a Macrocyclic Nickel(II) Complex Using Sodium Borohydride: Synthesis of a Complex Bearing Two N-(2-Aminoethyl) Pendant Arms

    International Nuclear Information System (INIS)

    The stepwise protonation constants for [NiL2]2+ were determined by a spectrophotometric titration.17 The approximate pKa1 value (ca. 3.6) was found to be somewhat larger than the pKa2 value (ca. 2.4), as usual. The low pKa1 and pKa2 values may be result from the relatively strong interactions between the functional groups and the central metal of the complex. NaBH4 is an efficient reagent for the reduction of [NiL1]2+ in the presence of methanol, even though the N-CH2CN groups are not involved in coordination. The stepwise protonation constants for [NiL2]2+ indicate that the pendant amino groups-central metal interactions are relatively strong

  6. Cobalt,a reactive metal in releasing hydrogen from sodium borohydride by hydrolysis:A short review and a research perspective

    Institute of Scientific and Technical Information of China (English)

    DEMIRCI; Umit; B; AKDIM; Ouardia; HANNAUER; Julien; CHAMOUN; Rita; MIELE; Philippe

    2010-01-01

    Cobalt is commonly admitted as being a promising catalyst in accelerating NaBH4 hydrolysis,being as reactive as noble metals and much more cost-effective.This is the topic of the present paper.Herein,we survey(i) the NaBH4-devoted literature while especially focusing on the Co catalysts and(ii) our work on the same topic.Finally,we report(iii) reactivity results of newly developed Co-based catalysts.From both surveys,it mainly stands out that Co has been investigated as catalysts in various forms:namely,as chlorides,reduced nanoparticles(metal Co,Co boride,Co-B alloy),supported over supports and shaped.In doing so the reactivity can be easily varied achieving H2 generation rates from few to >1000 L(H2)/min·g(metal).Nevertheless,our work can be distinguished from the NaBH4 literature.Indeed,we are working on strategies that focus on making alternative Co-based catalysts.One of these strategies is illustrated here as we report new reactivity data of Co-based bimetallic supported catalysts.For example,we show that 20 wt% Co90Y10/γAl2O3-20 wt% Co95Hf5/γAl2O3 > 20 wt% Co99Zr1/γAl2O3 > 20 wt% Co/γAl2O3,the best catalysts showing HGRs of about 245 mL(H2)/min or 123 L(H2) /min·g(metals).

  7. Synthesis of nanocrystalline REBO3 (RE=Y, Nd, Sm, Eu, Gd, Ho) and YBO3:Eu using a borohydride-based solution precursor route

    International Nuclear Information System (INIS)

    A solution precursor route has been used to synthesize a series of nanocrystalline rare-earth borates. Amorphous precursor powders are precipitated during an aqueous reaction between RE3+ and NaBH4, and the isolated powders can be annealed in air at 700 deg. C to form YBO3, NdBO3, SmBO3, EuBO3, GdBO3, and HoBO3. YBO3:Eu formed using this strategy shows red-orange emission properties that are similar to high-quality nanocrystals prepared by other methods. The materials have been characterized by FTIR spectroscopy, powder XRD, SEM, DSC, UV-Vis fluorimetry, and TEM with EDS and element mapping. - Graphical abstract: Amorphous nanoscopic precursor powders are formed through the aqueous reaction of RE3+ with NaBH4. Once isolated, the powders can be annealed at 700 deg. C in air to form a series of nanocrystalline REBO3 orthoborates. Nanocrystalline YBO3:Eu formed using this strategy shows red-orange emission properties when excited with UV light

  8. Halide Free M(BH4)2 (M = Sr, Ba, and Eu) Synthesis, Structure, and Decomposition.

    Science.gov (United States)

    Sharma, Manish; Didelot, Emilie; Spyratou, Alexandra; Lawson Daku, Latévi Max; Černý, Radovan; Hagemann, Hans

    2016-07-18

    Borohydrides have attained high interest in the past few years due to their high volumetric and gravimetric hydrogen content. Synthesis of di/trimetallic borohydride is a way to alter the thermodynamics of hydrogen release from borohydrides. Previously reported preparations of M(BH4)2 involved chloride containing species such as SrCl2. The presence of residual chloride (or other halide) ions in borohydrides may change their thermodynamic behavior and their decomposition pathway. Pure monometallic borohydrides are needed to study decomposition products without interference from halide impurities. They can also be used as precursors for synthesizing di/trimetallic borohydrides. In this paper we present a way to synthesize halide free alkaline earth metal (Sr, Ba) and europium borohydrides starting with the respective hydrides as precursors. Two novel high temperature polymorphs of Sr and Eu borohydrides and four polymorphs of Ba borohydride have been characterized by synchrotron X-ray powder diffraction, thermal analysis, and Raman and infrared spectroscopy and supported by periodic DFT calculations. The decomposition routes of these borohydrides have also been investigated. In the case of the decomposition of strontium and europium borohydrides, the metal borohydride hydride (M(BH4)H3, M = Sr, Eu) is observed and characterized. Periodic DFT calculations performed on room temperature Ba(BH4)2 revealed the presence of bidentate and tridentate borohydrides. PMID:27351948

  9. Effect of Reduction by Sodium Borohydride on the Structural Characteristics of Brown-Rotted Lignin%硼氢化钠还原对褐腐木质素结构特征的影响

    Institute of Scientific and Technical Information of China (English)

    李改云; 孙其宁; 秦特夫; 黄洛华

    2010-01-01

    采用FTLR、UV-Visible、NMR和GPC分析手段研究了褐腐木质素被.NaBH4还原前后的化学结构变化.FTIR表明褐腐木质素还原后1677 cm-1处与苯环共轭的羰基峰消失,1715 cm-1处非共轭羰基峰强度减弱,1509和1603 cm-1处苯环骨架振动吸收峰强度变化很小;UV表明褐腐木质素还原后位于288 nm的最强吸收峰和300~400nm区域的吸收强度降低;1H NMR表明褐腐木质素还原后甲氧基和酚羟基数量减少,醇羟基数量增加,褐腐木质素芳香环和结构单元联接键上的氢质子数增加;GPC表明褐腐木质素还原后分子量分布向高分子区域扩展,数均和重均分子量增大,分子量分布明显变宽.NaBH4在碱性环境中可以将褐腐木质素中的共轭羰基完全还原为羟基,非共轭羰基部分还原为羟基,其侧链结构部分被改变,苯环结构稳定,褐腐木质素在还原过程中发生了缩合反应.

  10. The use of superporous p(AAc (acrylic acid)) cryogels as support for Co and Ni nanoparticle preparation and as reactor in H2 production from sodium borohydride hydrolysis

    International Nuclear Information System (INIS)

    Here, we report for the first time the use of p(AAc (p(acrylic acid)) cryogel for in situ metal nanoparticle preparation, and their use as a superporous reactor for H2 generation from hydrolysis of NaBH4. Superporous p(AAc) cryogels and conventional hydrogels were prepared via free radical polymerization technique at low (−18 °C) and moderate (40 °C) temperatures, respectively. They were characterized by employing various methods such as swelling experiments, optical imaging, and SEM (Scanning Electron Microscopy) analysis. By reducing Co2+ and Ni2+ ions within p(AAc) cryogel and hydrogel matrices, the obtained Co and Ni metal nanoparticles were employed for H2 generation from NaBH4 hydrolysis. Various factors such as porosity, metal type, temperature, and the amount of sodium hydroxide were investigated to determine their effects on hydrogen generation from NaBH4 hydrolysis. Activation energy (Ea), enthalpy (ΔH#) and entropy (ΔS#) for NaBH4 hydrolysis by superporous p(AAc)-Co metal composites were 29.35 kJ mol−1,=36.85 kJ mol−1, and –157.88 J mol−1K−1, respectively. Cryogels showed better catalytic activity than conventional hydrogels in the hydrolysis reaction, and have a higher TOF (turnover frequency) value of 4.10 mol H2 (mol catalyst min)−1 compared to conventional hydrogels, due to its highly porous nature, short diffusion distances and fast response times. - Highlights: • Superporous cryogel supports for in situ metal nanoparticle preparation. • Fast H2 production from chemical hydride hydrolysis by cryogel-M composites. • Soft, superporous cryogel reactors for energy applications

  11. Development of binary anodic catalysts for direct oxidation of borohydride%硼氢化物直接氧化的二元催化剂研究进展

    Institute of Scientific and Technical Information of China (English)

    余丹梅; 申燕; 李小艳; 张代雄; 王洁

    2011-01-01

    直接硼氢燃料电池(DBFC)是一种以NaBH4/KBH4碱性溶液为阳极燃料的新型燃料电池.催化剂的种类严重影响着硼氢化物的直接氧化.综述了近年来直接硼氢燃料电池(DBFC)阳极用NiPt、Ni-Pd、Ag-Ni、Au-Co、Au-Pt等二元催化剂的研究现状.

  12. Hydrogen storage material and related processes

    Science.gov (United States)

    Soloveichik; Grigorii Lev , Andrus; Matthew John

    2010-07-13

    Disclosed herein is a composition comprising a complex hydride and a borohydride catalyst wherein the borohydride catalyst comprises a BH.sub.4 group, and a group IV metal, a group V metal, or a combination of a group IV and a group V metal. Also disclosed herein are methods of making the composition.

  13. Ambient Ionic Liquids Used in the Reduction ofAldehydes and Ketones

    Institute of Scientific and Technical Information of China (English)

    Dan Qian XU; Shu Ping LUO; Bao You LIU; Zhen Yuan XU; Yin Chu SHEN

    2004-01-01

    The sodium borohydride reduction of aldehydes and ketones to corresponding alcohols has been accomplished via the use of ionic liquids. The alcohols are easily obtained with excellent yields and the ionic liquid BMImBF4 could be reused.

  14. A novel synthesis of ethanolamine-2-14C

    International Nuclear Information System (INIS)

    Ethanolamine-2-14C was prepared by the reduction of benzyloxycarbonyl-glycine-1-14C methyl ester. The reduction was carried out with calcium borohydride and the protecting group was removed by hydrogenolysis. (author)

  15. Effect of certain structural features of coal on Its tendency towards reduction

    Energy Technology Data Exchange (ETDEWEB)

    Grigor' yeva, Ye. A.; Bakirova, Ye.V.; Dzhalyabova, L.V.; Larina, N.K.; Lesnikova, Ye.B.; Zharova, M.N.,

    1981-01-01

    A study is made of the effect of easily destroyed ether groupings and organic-mineral bonds in coal structure on the tendency towards reduction with the help of hydrolytic destruction of coals and subsequent selective reduction by sodium borohydride.

  16. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    OpenAIRE

    Sequeira, César A. C.; Santos, Diogo M. F.; Morais, Ana L.; Biljana Šljukić

    2012-01-01

    Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both a...

  17. Innovative Materials and Systems for Solid State Hydrogen Storage

    OpenAIRE

    Capurso, Giovanni

    2013-01-01

    The research presented in this doctoral thesis concerns with the development of novel materials and systems for solid state hydrogen storage. The first group of works presented is on alkaline and alkaline-earth borohydrides. The possibility to enhance their properties with the help of nanosupports has been widely explored. An attempt to improve the dehydrogenation kinetics of lithium borohydride has been made dispersing this material on the surface of modified nanotubes and gra...

  18. Solid-state rechargeable magnesium battery

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yuyan; Liu, Jun; Liu, Tianbiao; Li, Guosheng

    2016-09-06

    Embodiments of a solid-state electrolyte comprising magnesium borohydride, polyethylene oxide, and optionally a Group IIA or transition metal oxide are disclosed. The solid-state electrolyte may be a thin film comprising a dispersion of magnesium borohydride and magnesium oxide nanoparticles in polyethylene oxide. Rechargeable magnesium batteries including the disclosed solid-state electrolyte may have a coulombic efficiency .gtoreq.95% and exhibit cycling stability for at least 50 cycles.

  19. Synthesis and characterization of silver colloidal nanoparticles with different coatings for SERS application

    Energy Technology Data Exchange (ETDEWEB)

    Mikac, L.; Ivanda, M., E-mail: ivanda@irb.hr [Ruđer Bošković Institute, Laboratory for Molecular Physics (Croatia); Gotić, M. [Ruđer Bošković Institute, Laboratory for Synthesis of New Materials (Croatia); Mihelj, T. [Ruđer Bošković Institute, Laboratory for Synthesis and Processes of Self-assembling of Organic Molecules (Croatia); Horvat, L. [Ruđer Bošković Institute, Laboratory for Electron Microscopy (Croatia)

    2014-12-15

    Silver colloids were produced by chemical reduction of silver salt (silver nitrate, AgNO{sub 3}) solution. As reducing agents, trisodium citrate, sodium borohydride, ascorbic acid, polyvinylpyrrolidone, and glucose were used. The colloids were characterized by UV–Vis, DLS, zeta potential measurements, and SEM. The colloids were stabilized with negative groups or large molecules attached to their surface. The surface-enhanced Raman scattering (SERS) effect of stabilized nanoparticles was measured by using pyridine and rhodamine 6G molecules as analytes and NaNO{sub 3}, KCl, and KBr at different concentrations as aggregating agents. The best Raman signal enhancement was achieved using silver nanoparticles of 40 nm size reduced and stabilized with citrate. The SERS signal of analyte molecules was further enhanced with the addition of sodium borohydride as an alternative aggregating agent. The borohydride had the strongest impact on the SERS effect of the colloid consistent of large (0.5 µm) silver nanoparticles stabilized with aminodextran. The mixture colloid-borohydride-pyridine was stable for hours. The mechanism of borohydride in the colloids is discussed.

  20. Synthesis and characterization of silver colloidal nanoparticles with different coatings for SERS application

    International Nuclear Information System (INIS)

    Silver colloids were produced by chemical reduction of silver salt (silver nitrate, AgNO3) solution. As reducing agents, trisodium citrate, sodium borohydride, ascorbic acid, polyvinylpyrrolidone, and glucose were used. The colloids were characterized by UV–Vis, DLS, zeta potential measurements, and SEM. The colloids were stabilized with negative groups or large molecules attached to their surface. The surface-enhanced Raman scattering (SERS) effect of stabilized nanoparticles was measured by using pyridine and rhodamine 6G molecules as analytes and NaNO3, KCl, and KBr at different concentrations as aggregating agents. The best Raman signal enhancement was achieved using silver nanoparticles of 40 nm size reduced and stabilized with citrate. The SERS signal of analyte molecules was further enhanced with the addition of sodium borohydride as an alternative aggregating agent. The borohydride had the strongest impact on the SERS effect of the colloid consistent of large (0.5 µm) silver nanoparticles stabilized with aminodextran. The mixture colloid-borohydride-pyridine was stable for hours. The mechanism of borohydride in the colloids is discussed

  1. Investigation of nanostructured platinum-nickel supported on the titanium surface as electrocatalysts for alkaline fuel cells

    Science.gov (United States)

    Tamašauskaitė-Tamašiūnaitė, L.; Balčiūnaitė, A.; Vaiciukevičienė, A.; Selskis, A.; Pakštas, V.

    2012-06-01

    This study involves the formation of nanostructured platinum-nickel supported on the titanium surface catalysts using the galvanic displacement technique and investigation of their electrocatalytic activity toward the oxidation of borohydride, methanol and ethanol in an alkaline media by cyclic voltammetry and chronoamperometry. Scanning electron microscopy, Energy Dispersive X-ray Spectroscopy and X-ray diffraction were used to characterize the surface structure, composition and morphology. The nanoPt(Ni)/Ti and nanoPt/Ti catalysts exhibited a higher catalytic efficiency to the oxidation of borohydride, ethanol and methanol as compared with that of pure Pt.

  2. Properties of amorphous FeCoB alloy particles (abstract)

    DEFF Research Database (Denmark)

    Charles, S. W.; Wells, S.; Meagher, A.;

    1988-01-01

    Amorphous and crystalline alloy particles (0.05–0.5 nm) of FexCoyBz in which the ratio x:y ranges from 0 to 1 have been prepared by the borohydride reduction of iron and cobalt salts in aqueous solution. The structure of the particles has been studied using Mössbauer spectroscopy and x....... 1). It has been shown that the fraction of boron in the alloys (10–35 at. %) is dependent upon the rate of addition of salts to borohydride and the concentration of cobalt present; this in turn influences the crystallinity and magnetic properties . Journal of Applied Physics is copyrighted...

  3. Amorphous TM1−xBx alloy particles prepared by chemical reduction (invited)

    DEFF Research Database (Denmark)

    Linderoth, Søren; Mørup, Steen

    1991-01-01

    Amorphous transition-metal boron (TM-B) alloy particles can be prepared by chemical reduction of TM ions by borohydride in aqueous solutions. ln the last few years systematic studies of the parameters which control the composition, and, in turn, many of the properties of the alloy particles, have...... been performed and are reviewed in the present paper. The most important preparation parameters which influence the composition are the concentration of the borohydride solution and the pH of the TM salt solution. By controlling these parameters it is possible to prepare amorphous alloy samples...

  4. Primary structure determination of five sialylated oligosaccharides derived from bronchial- mucus glycoproteins of patients suffering from cystic fibrosis. The occurrence of the NeuAcα(2→3)Galα(1→4)[Fucα(1→3)]GlcNAcα(1→.) structural element revealed by 500-MHz 1H NMR spectroscopy

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Lamblin, G.; Boersma, A.; Klein, A.; Roussel, P.; Halbeek, H. van

    1984-01-01

    The structure of sialylated carbohydrate units of bronchial mucins obtained from cystic fibrosis patients was investigated by 500-MHz 1H NMR spectroscopy in conjunction with sugar analysis. After subjecting the mucins to alkaline borohydride degradation, sialylated oligosaccharide-alditols were isol

  5. The synthesis of [2-13C]2-nitropropane at room temperature and at atmospheric pressure

    NARCIS (Netherlands)

    Jacquemijns M; Zomer G

    1990-01-01

    In this report the synthesis of [2-13C]2-nitropropane at room temperature is described. [2-13C]Acetone was converted into the oxime with hydroxy hydrochloridelamine and sodium carbonate. Treatment with hypobromic acid resulted in 2-13C]2-bromo-2-nitropropane. Hydrogenation with sodium borohydride

  6. Characterization of silver nanoparticles deposited on montmorillonite

    Czech Academy of Sciences Publication Activity Database

    Praus, P.; Turicová, M.; Machovič, V.; Študentová, S.; Klementová, Mariana

    2010-01-01

    Roč. 49, č. 3 (2010), s. 341-345. ISSN 0169-1317 Institutional research plan: CEZ:AV0Z40320502 Keywords : silver nanoparticles * formaldehyde and borohydride reduction * montmorillonite * surface enhanced Raman scattering Subject RIV: CA - Inorganic Chemistry Impact factor: 2.303, year: 2010

  7. Solid State NMR Characterization of Complex Metal Hydrides systems for Hydrogen Storage Applications

    OpenAIRE

    Hwang, Son-Jong; Bowman, Robert C., Jr.; Kim, Chul; Zan, Jason A.; Reiter, Joseph W.

    2011-01-01

    Solid state NMR is widely applied in studies of solid state chemistries for hydrogen storage reactions. Use of ^(11)B MAS NMR in studies of metal borohydrides (BH_4) is mainly focused, revisiting the issue of dodecaborane formation and observation of ^(11)B{^1H} Nuclear Overhauser Effect.

  8. NMR Studies of Structure-Reactivity Relationships in Carbonyl Reduction: A Collaborative Advanced Laboratory Experiment

    Science.gov (United States)

    Marincean, Simona; Smith, Sheila R.; Fritz, Michael; Lee, Byung Joo; Rizk, Zeinab

    2012-01-01

    An upper-division laboratory project has been developed as a collaborative investigation of a reaction routinely taught in organic chemistry courses: the reduction of carbonyl compounds by borohydride reagents. Determination of several trends regarding structure-activity relationship was possible because each student contributed his or her results…

  9. Preparation of Copper Nanoparticles and Catalytic Properties for the Reduction of Aromatic Nitro Compounds

    International Nuclear Information System (INIS)

    A novel copper nanoparticles were synthesized from cupric sulfate using hydrazine as reducing reagents. A series of aromatic nitro compounds were reacted with sodium borohydride in the presence of the copper nanoparticles catalysts to afford the aromatic amino compounds in high yields. Additionally, the catalysts system can be recycled and maintain a high catalytic effect in the reduction of aromatic nitro compounds

  10. The reduction ring-opening reaction of imidazoline

    Institute of Scientific and Technical Information of China (English)

    史真; 李诤; 白银娟

    2000-01-01

    A new reduction ring-opening reaction of 2-imidazoline with sodium borohydride is reported, and the effect of reaction condition on the yield, reaction mechanism and the use of the new reaction in synthesis of ethylenediamine derivatives are discussed. A new method for the preparation of unsymmetrical substituted ethylenediamine via the reduction ring-opening reaction of imidazoline is provided.

  11. Reductive Deprotection of Monolayer Protected Nanoclusters: An Efficient Route to Supported Ultrasmall Au Nanocatalysts for Selective Oxidation

    Czech Academy of Sciences Publication Activity Database

    Das, S.; Goswami, A.; Hesari, M.; Al-Sharab, J. F.; Mikmeková, Eliška; Maran, F.; Asefa, T.

    2014-01-01

    Roč. 10, č. 8 (2014), s. 1473-1478. ISSN 1613-6810 R&D Projects: GA MŠk(CZ) LO1212 Keywords : gold nanoclusters * selective oxidation * heterogeneous nanocatalysis * styrene oxidation * borohydride reduction Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 8.368, year: 2014

  12. The fabrication and option characteristics of polyethylene glycol-coated gold nanoparticles with different size

    International Nuclear Information System (INIS)

    Objective: To synthesize gold nanoparticles (GNPs) and polyethylene glycol-coated GNPs (PEG-GNPs)modified by sulfhydryl-polyethylene glycol (SH-PEG), chloroauric acid and different reductant agent,such as trisodium citrate and sodium borohydride were used. Methods: Chloroauric acid solution was brought to a boil,and then different volume of trisodium citrate solution or sodium borohydride solution was added to the boiling solution. Then the mixture was boiled for a further 30 minutes. Subsequently some SH-PEG was mixed with the GNPs and stirred for 1 hour to fabricate the PEG-GNPs. The optical characteristic and size of GNPs and PEG-GNPs were observed by UV-Vis spectrophotometer and transmission electron microscopic respectively. Results: 10, 25, and 45 nm GNPs were fabricated using 1% trisodium citrate,while the 5 nm GNPs were synthesized using 0.11% sodium borohydride. Meanwhile, SH-PEG was added to the GNPs and obtained the PEG-GNPs. Furthermore, when compared with the GNPs with different size,it can be found that the surface plasmon resonance (SPR) of GNPs have shift to long wavelength region with increasing particles size. The same phenomenon also can be found in the PEG-GNPs with different size. Conclusions: The size of GNPs can be modulated by controlling the ratio between chloroauric acid and trisodium citrate or sodium borohydride. Meanwhile, the larger the size of GNPs is, the more significant of the shifting to the long wavelength of SPR is. (authors)

  13. Direct reduction of some benzoic acids to alcohols via NaBH4-Br2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Direct reduction of seven benzoic acids to alcohols via sodium borohydride-bromine (NaBH4-Br2) reagent was developed. The isolated yields for the seven acids to reduce reached 60.6-90.1 %. This new synthesis route has the advantages of simple of application, low cost, mild nature, and satisfactory yields.

  14. Synthesis of radiolabelled clenbuterol analogues

    International Nuclear Information System (INIS)

    Oxidation of clenbuterol with pyridinium chlorochromate yielded 4-amino-3,5-dichloro-α-tert.-butylaminoacetophenone 5. Tritiated clenbuterol was produced by reduction of 5 with sodium [3H]borohydride. Radioiodination of the clenbuterol precursor [2-tert.-butylamino-1-(4-aminophenyl)-ethanol] yielded [2-tert.-butylamino-1-(4-amino-3-[125I] iodophenyl)-ethanol]. (author)

  15. Preparation of 2-deoxyaldoses from aldose phenylhydrazones

    DEFF Research Database (Denmark)

    Jørgensen, Christel Thea; Pedersen, Christian

    1997-01-01

    Acetylation of D-mannose phenylhydrazone gives acetylated D-arabino-1-phenyl-azo-1-(E)-hexene. Subsequent reduction with sodium borohydride produces 2-deoxy-D-arabino-hexose phenylhydrazone which, on hydrolysis, gives 2-deoxy-D-arabino-hexose. By a similar procedure 2-deoxy-D-lyxo-hexose, 2...

  16. Synthesis and Stabilization of Fe-Nd-B Nanoparticles for Biomedical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Haik, Yousef, E-mail: haik@eng.fsu.edu, E-mail: yhaik@uaeu.ac.ae; Chatterjee, Jhunu; Ching, Jen Chen [Florida State University, Center for Nanomagnetics and Biotechnology (United States)

    2005-12-15

    Stable composition of Iron Neodymium Boron nanoparticles are formed by a chemical method. Conventional borohydride reduction method was used. The particles are in the size range of 30-100 nm. Silica coating was applied to stabilize and prepare the particles for in vitro applications such as cell separation and diagnostics. Morphology of particles has been studied along with the structure and magnetic properties.

  17. Development of Hydrogen Storage Tank Systems Based on Complex Metal Hydrides

    Directory of Open Access Journals (Sweden)

    Morten B. Ley

    2015-09-01

    Full Text Available This review describes recent research in the development of tank systems based on complex metal hydrides for thermolysis and hydrolysis. Commercial applications using complex metal hydrides are limited, especially for thermolysis-based systems where so far only demonstration projects have been performed. Hydrolysis-based systems find their way in space, naval, military and defense applications due to their compatibility with proton exchange membrane (PEM fuel cells. Tank design, modeling, and development for thermolysis and hydrolysis systems as well as commercial applications of hydrolysis systems are described in more detail in this review. For thermolysis, mostly sodium aluminum hydride containing tanks were developed, and only a few examples with nitrides, ammonia borane and alane. For hydrolysis, sodium borohydride was the preferred material whereas ammonia borane found less popularity. Recycling of the sodium borohydride spent fuel remains an important part for their commercial viability.

  18. Uranium isotope separation in the solid state. Final report for period ending September 30, 1978

    International Nuclear Information System (INIS)

    The final results of an investigation on the isotope separation of uranium in the solid state are presented in this report. The feasibility of separating uranium isotopes using the proposed system based on uranium borohydride (borodeuteride) in a low temperature mixed crystal has been determined. The first section of the report summarizes the background material relating to this work which includes: a calculation of isotope shifts (borodeuteride), details on the two-step, two-photon spectroscopic isotope separation technique, and a brief overview of the method and equipment used for separating uranium isotopes in the solid state. The second section concerns the experimental details of the present work performed in the laboratory. Representative spectroscopic data obtained in this investigation are presented and discussed in the third section. Finally, the report is concluded with recommendations for further investigations on the uranium borohydride (borodeuteride) system for isotope separation

  19. Synthesis of polyol based Ag/Pd nanocomposites for applications in catalysis

    Directory of Open Access Journals (Sweden)

    J.A. Adekoya

    2014-01-01

    Full Text Available The synthesis of polyvinylpyrrolidone seed mediated Ag/Pd allied nanobimetallic particles was successfully carried out by the simultaneous reduction of the metal ions in ethylene glycol, diethylene glycol, glycerol, pentaerythritol and sodium borohydride solution. The optical measurement revealed the existence of peak broadening that causes diffusion processes of the metal sols to decrease making it possible to monitor the changes spectrophotometrically. This, together with X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, transmission electron microscopy (TEM and high resolution TEM measurements strongly support the conclusion that intimately alloyed clusters were formed and the particle growth anisotropy is diffusion limited. Finally, the catalytic potential of the nanocomposites was investigated using 4-nitrophenol in the presence of sodium borohydride at 299 K; a good linear fitting of ln(A/A0 versus the reaction time was obtained, indicating pseudo-first-order kinetics.

  20. Tailoring Thermodynamics and Kinetics for Hydrogen Storage in Complex Hydrides towards Applications.

    Science.gov (United States)

    Liu, Yongfeng; Yang, Yaxiong; Gao, Mingxia; Pan, Hongge

    2016-02-01

    Solid-state hydrogen storage using various materials is expected to provide the ultimate solution for safe and efficient on-board storage. Complex hydrides have attracted increasing attention over the past two decades due to their high gravimetric and volumetric hydrogen densities. In this account, we review studies from our lab on tailoring the thermodynamics and kinetics for hydrogen storage in complex hydrides, including metal alanates, borohydrides and amides. By changing the material composition and structure, developing feasible preparation methods, doping high-performance catalysts, optimizing multifunctional additives, creating nanostructures and understanding the interaction mechanisms with hydrogen, the operating temperatures for hydrogen storage in metal amides, alanates and borohydrides are remarkably reduced. This temperature reduction is associated with enhanced reaction kinetics and improved reversibility. The examples discussed in this review are expected to provide new inspiration for the development of complex hydrides with high hydrogen capacity and appropriate thermodynamics and kinetics for hydrogen storage. PMID:26638824

  1. Studies on the preparation of labelled compounds for γ-scintigraphy use

    International Nuclear Information System (INIS)

    To develop 99mTc instant labelling kit of d,1-HMPAO and 131I labelled IMP for the regional cerebral blood flow scintigraphic use, d,1-HMPAO and IMP were synthesized. The former was prepared from 2,3-butadione monoxim and 2,2-dimethyl-1,3-propanediamine in the presence of cation exchange resin, and then selective reduction of imine bond with sodium borohydride followed by fractional crystallization of diastereometric mixture of HMPAO. The latter was prepared by condensation of p-iodophenylpropanone with isopropylamine, and then reduction of double bond with sodium borohydride. For the preparation of 99mTc labelled HSA, experiments on incorporation of bifunctional chelating agent of DTPA to HSA, establishment of optimal conditions of 99mTc labelling, determination of labelling yield and radiochemical purity, and examination of stability were carried out. (Author)

  2. Synthesis and Thermal Behavior of Metallic Cobalt Micro and Nanostructures

    Institute of Scientific and Technical Information of China (English)

    Marlene Gonzalez Montiel; P Santiago-Jacinto; J A I Daz Gongora; E Reguera; Geonel Rodrguez-Gattorno

    2011-01-01

    In this contribution, a comparative study of metallic cobalt micro and nanoparticles obtained in solution by four different chemical routes is reported. Classic routes such as borohydride reduction in aqueous media and the so-called polyol methodology were used to obtain the cobalt nanostructures to be studied. Using CTAB as surfactant, cobalt hollow nanostructures were obtained. The use of strong reducing agents, like sodium borohydride, favors the formation of quasi-monodispersed nanoparticles of about 2 nm size but accompanied with impurities; for hydrazine (a mild reducer), nanoparticles of larger size are obtained which organize in spherical microagglomerates. Valuable information on the particles thermal stability and on nature of the species anchored at their surface was obtained from thermogravimetric curves. The samples to be studied were characterized from UV-vis, IR, X-ray diffraction, and electron microscopy images (scanning and transmission).

  3. Platinum- and membrane-free swiss-roll mixed-reactant alkaline fuel cell.

    Science.gov (United States)

    Aziznia, Amin; Oloman, Colin W; Gyenge, Előd L

    2013-05-01

    Eliminating the expensive and failure-prone proton exchange membrane (PEM) together with the platinum-based anode and cathode catalysts would significantly reduce the high capital and operating costs of low-temperature (monolithic carbon fiber materials (referred to as an osmium 3D anode). The borohydride-oxygen SR-MRFC operates at 323 K and near atmospheric pressure, generating a peak power density of 1880 W m(-2) in a single-cell configuration by using an osmium-based anode (with an osmium loading of 0.32 mg cm(-2)) and a manganese dioxide gas-diffusion cathode. To the best of our knowledge, 1880 W m(-2) is the highest power density ever reported for a mixed-reactant fuel cell operating under similar conditions. Furthermore, the performance matches the highest reported power densities for conventional dual chamber PEM direct borohydride fuel cells. PMID:23589385

  4. Efficient synthesis of 1,3,5-oxygenated synthons from dimethyl 3-oxoglutarate: first use of borane-dimethyl sulfide complex as a regioselective reducing agent of 3-oxygenated glutarate derivatives

    International Nuclear Information System (INIS)

    The selective reduction of dimethyl 3-oxoglutarate was accomplished in different levels. A high yielding sodium borohydride reduction of the keto group is fully described leading to dimethyl 3-hydroxyglutarate. When borane-dimethyl sulfide (BMS) complex was used, a diol or a triol compound can be obtained by selective or total reduction of 3-hydroxy- or 3-oxoglutarate, respectively, allowing an efficient and practical route to 1,3,5-oxygenated compounds. (author)

  5. Technetium-99m labeling of tityustoxin and venom from the scorpion Tityus serrulatus

    Energy Technology Data Exchange (ETDEWEB)

    Nunan, E.A.; Cardoso, V.N.; Moraes-Santos, T. E-mail: tmoraes@dedalus.lcc.ufmg.br

    2002-12-01

    The tityustoxin, the most toxic fraction from scorpion Tityus serrulatus venom, has been used as a tool in several neurochemical and neuropharmacological studies. Biological activities of labeled and unlabeled tityustoxin and venom were compared. The samples were labeled in the presence of stannous chloride and sodium borohydride with a yield of 60-70% for the venom and 75-85% for tityustoxin and then chromatographed in Sephadex G-10. Biological activities of tityustoxin and venom were preserved after labeling.

  6. A Study of Groundwater Matrix Effects for the Destruction of Trichloroethylene Using Fe/Pd Nanoaggregates

    Energy Technology Data Exchange (ETDEWEB)

    meyer, D E [Univ of KY, dept of chemical and materials engineering; Hampson, Steve [Univ of KY Center for Applied Energy Research - Ky Research Consortium of Energy and Environment; ormsbee, Lindelle [Univ of KY Center for Applied Energy Research - Ky Research Consortium of Energy and Environment; Bhattacharyya, Dibakar [univ of KY, Dept of Chemical and Materials Engineering

    2008-06-01

    Fe nanoaggregates have been prepared using the sodium borohydride reduction method and post-coated with Pd using aqueous phase electro-depostition. The Fe/Pd particles have been used to examine dechlorination of TCE with regard to matrix effects using materials representative of examine dechlorination of TCE with regard to matrix effects using materials representative of a potential zero-valent metal remediation site surrounding the Paducah Gaseous Diffusion Plant in Paducah, KY.

  7. The synthesis of [2-13C]2-nitropropane at room temperature and at atmospheric pressure

    OpenAIRE

    Jacquemijns M; Zomer G

    1990-01-01

    In this report the synthesis of [2-13C]2-nitropropane at room temperature is described. [2-13C]Acetone was converted into the oxime with hydroxy hydrochloridelamine and sodium carbonate. Treatment with hypobromic acid resulted in 2-13C]2-bromo-2-nitropropane. Hydrogenation with sodium borohydride gave [2-13C]2-nitropropane in 14,3% overall yield.

  8. Synthesis of radiolabelled clenbuterol analogues

    Energy Technology Data Exchange (ETDEWEB)

    Pegg, G.C.; Sleeman, M.J. (University College of Central Queensland, Rockhampton, M.C. (Australia). Dept. of Chemistry); Sillence, M.N.; Lindsay, D.B. (Commonwealth Scientific and Industrial Research Organization, North Rockhampton, Queensland (Australia). Tropical Cattle Research Ccentre)

    1991-12-01

    Oxidation of clenbuterol with pyridinium chlorochromate yielded 4-amino-3,5-dichloro-{alpha}-tert.-butylaminoacetophenone 5. Tritiated clenbuterol was produced by reduction of 5 with sodium ({sup 3}H)borohydride. Radioiodination of the clenbuterol precursor (2-tert.-butylamino-1-(4-aminophenyl)-ethanol) yielded (2-tert.-butylamino-1-(4-amino-3-({sup 125}I) iodophenyl)-ethanol). (author).

  9. Effect of experimentally induced reducing conditions on the mobility of arsenic from a mining soil

    Energy Technology Data Exchange (ETDEWEB)

    Chatain, Vincent [Laboratoire d' Analyse Environnementale des Procedes et des Systemes Industriels, Institut National des Sciences Appliquees de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Sanchez, Florence [Department of Civil and Environmental Engineering, Vanderbilt University, Station B-35 1831, Nashville, TN 37235 (United States)]. E-mail: Florence.sanchez@Vanderbilt.edu; Bayard, Remy [Laboratoire d' Analyse Environnementale des Procedes et des Systemes Industriels, Institut National des Sciences Appliquees de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Moszkowicz, Pierre [Laboratoire d' Analyse Environnementale des Procedes et des Systemes Industriels, Institut National des Sciences Appliquees de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Gourdon, Remy [Laboratoire d' Analyse Environnementale des Procedes et des Systemes Industriels, Institut National des Sciences Appliquees de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France)

    2005-06-30

    A method for estimating the release of contaminants from contaminated sites under reducing conditions is proposed. The ability of two chemical reducing agents, sodium ascorbate and sodium borohydride, to produce different redox environments in a gold mining soil contaminated with arsenic was investigated. Liquid-solid partitioning experiments were carried out in the presence of each of the reducing agents at different pH conditions. Both the effect of varying concentrations of the reducing agent and the effect of varying pH in the presence of a constant concentration of the reducing agent were studied. Concentrations of sodium ascorbate ranging from 0.0075 to 0.046 mol L{sup -1} and concentrations of sodium borohydride ranging from 0.0075 to 0.075 mol L{sup -1} were examined. The addition of varying concentrations of sodium borohydride provided greater reducing conditions (ranging from -500 to +140 mV versus NHE) than that obtained using sodium ascorbate (ranging from -7 to +345 mV versus NHE). The solubilization of arsenic and iron was significantly increased by the addition of sodium ascorbate for all concentrations examined and pH tested, compared to that obtained under oxidizing conditions (as much as three orders of magnitude and four orders of magnitude, respectively, for the addition of 0.046 mol L{sup -1} of sodium ascorbate). In contrast, the alkaline and highly reduced soil conditions obtained with sodium borohydride lead to a lower effect on arsenic solubilization (as much as one order of magnitude for pH values between ca. 7 and 10 and no effect for pH values between ca. 10 and 12) and no effect on iron solubilization for all concentrations examined and pH tested. At similar ORP-pH conditions the results of extraction for arsenic and iron were different for the two reagents used.

  10. Deoxyiminoalditols from Aldonolactones - V. Preparation of the Four Stereoisomers of 1,5-Dideoxy-1,5-iminopentitols. Evaluation of these Iminopentitols and Three 1,5-Dideoxy-1,5-iminoheptitols as Glycosidase Inhibitors

    DEFF Research Database (Denmark)

    Godskesen, Michael Anders; Lundt, Inge; Madsen, Robert;

    1996-01-01

    aqueous ammonia, the 5-amino-5-deoxy-1,5-lactams, 2, 8, 12 and 17, respectively. Reduction of the lactam function using sodium borohydride/acetic or trifluoroacetic acid, or borane dimethyl sulfide complex yielded the iminopentitols. The compounds 3, 9, 13 and 18, together with the three 1,5-dideoxy-1......-substituted carbon atoms, were good inhibitors of alpha-L-fucosidase. Copyright (C) 1996 Elsevier Science Ltd...

  11. Production of Platinum Atom Nanoclusters at One End of Helical Plant Viruses

    OpenAIRE

    Yuri Drygin; Olga Kondakova; Joseph Atabekov

    2013-01-01

    Platinum atom clusters (Pt nanoparticles, Pt-NPs) were produced selectively at one end of helical plant viruses, tobacco mosaic virus (TMV) and potato virus X (PVX), when platinum coordinate compounds were reduced chemically by borohydrides. Size of the platinum NPs depends on conditions of the electroless deposition of platinum atoms on the virus. Results suggest that the Pt-NPs are bound concurrently to the terminal protein subunits and the 5′ end of encapsidated TMV RNA. Thus, a special st...

  12. Alkaline phosphatase for immunocytochemical labelling: problems with endogenous enzyme activity.

    OpenAIRE

    Bulman, A. S.; Heyderman, E

    1981-01-01

    Alkaline phosphatase may be used as a label for immunocytochemistry and can be demonstrated in tissue sections using the single step naphthol phosphate method. Endogenous enzyme activity may not be destroyed by fixation in formalin, formol alcohol, Carnoy's or Baker's solutions and should be inhibited before results are assessed. Either Bouin's solution or periodic acid followed by potassium borohydride are satisfactory inhibitor and do not adversely affect immunocytochemical results.

  13. Technetium-99m labeling of tityustoxin and venom from the scorpion Tityus serrulatus

    International Nuclear Information System (INIS)

    The tityustoxin, the most toxic fraction from scorpion Tityus serrulatus venom, has been used as a tool in several neurochemical and neuropharmacological studies. Biological activities of labeled and unlabeled tityustoxin and venom were compared. The samples were labeled in the presence of stannous chloride and sodium borohydride with a yield of 60-70% for the venom and 75-85% for tityustoxin and then chromatographed in Sephadex G-10. Biological activities of tityustoxin and venom were preserved after labeling

  14. $sup 3$H-metyrapol as a tool for studies of interactions of deoxycorticosterone with adrenal cortex mitochondria

    Energy Technology Data Exchange (ETDEWEB)

    Satre, M.; Lunardi, J.; Vignais, P.V.

    1972-05-01

    From international conference on mechanism in bioenergetica; Bari, Italy (1 May 1972). /sup 3/H-metyrapol was prepared by reduction of metyrapone with tritiated sodium borohydride. Metyrapol behaves like metyrapone as an inhibitor of the 11 BETA -hydroxylation of deoxycorticosterone in adrenal cortex mitochondria and competes with metyrapone in binding tests. These results, and the ease of preparation of highly labeled /sup 3/H-metyrapol, recommend /sup 3/ Hmetyrapol as a probe of deoxycorticosterone interactions with adrenal cortex mitochondria. (auth)

  15. RAPID DEGRADATION OF AZO DYES USING NANO-SCALE ZERO VALENT IRON

    OpenAIRE

    Nabila Rahman; Zainal Abedin; M. Ali Hossain

    2014-01-01

    In the present study, nano-scale Zero Valent Iron (NZVI) was synthesized in ethanol medium by the method of ferric iron reduction using sodium borohydride as a reducing agent under atmospheric conditions. The obtained iron nanoparticles are mainly in zero valent oxidation state and remain without significant oxidation for hours. A systematic characterization of NZVI was performed using XRD, SEM and TEM studies. The obtained iron nanoparticles consist of a zero valent core surrounding a rest o...

  16. Influence of the Synthesis Method for Pt Catalysts Supported on Highly Mesoporous Carbon Xerogel and Vulcan Carbon Black on the Electro-Oxidation of Methanol

    OpenAIRE

    Cinthia Alegre; María Elena Gálvez; Rafael Moliner; María Jesús Lázaro

    2015-01-01

    Platinum catalysts supported on carbon xerogel and carbon black (Vulcan) were synthesized with the aim of investigating the influence of the characteristics of the support on the electrochemical performance of the catalysts. Three synthesis methods were compared: an impregnation method with two different reducing agents, sodium borohydride and formic acid, and a microemulsion method, in order to study the effect of the synthesis method on the physico-chemical properties of the catalysts. X-ra...

  17. The heating effect of iron-cobalt magnetic nanofluids in an alternating magnetic field: application in magnetic hyperthermia treatment

    OpenAIRE

    Shokuhfar, Ali; Seyyed Afghahi, Seyyed Salman

    2013-01-01

    In this research, FeCo alloy magnetic nanofluids were prepared by reducing iron(III) chloride hexahydrate and cobalt(II) sulfate heptahydrate with sodium borohydride in a water/CTAB/hexanol reverse micelle system for application in magnetic hyperthermia treatment. X-ray diffraction, electron microscopy, selected area electron diffraction, and energy-dispersive analysis indicate the formation of bcc-structured iron-cobalt alloy. Magnetic property assessment of nanoparticles reveals that some s...

  18. Speciesion arsenic and selenium using hydride method atomic absorption spectroscopy

    International Nuclear Information System (INIS)

    Hydrides production - atomic absorption spectroscopy system was studied. Hydrides production tool and gas-liquid separator were tested and successfully used in this work. Hydride was produced through natrium borohydride reaction with sample solution. Emitted gas was separated by gas-liquid separator before it is carried by nitrogen gas through T tube which is put in atomic absorption flame spectrophotometer. Efficiency of the system was tested through standard reference sample and seawater / sediment samples which is collected from Negeri Johor water bays

  19. First-principles predicted low-energy structures of NaSc(BH4)4

    OpenAIRE

    Huan, Tran Doan; Amsler, Maximilian; Botti, Silvana; Marques, Miguel A. L.; Goedecker, Stefan

    2013-01-01

    According to previous interpretations of experimental data, sodium-scandium double-cation borohydride NaSc(BH$_4$)$_4$ crystallizes in the crystallographic space group $Cmcm$ where each sodium (scandium) atom is surrounded by six scandium (sodium) atoms. A careful investigation of this phase based on \\textit{ab initio} calculations indicates that the structure is dynamically unstable and gives rise to an energetically and dynamically more favorable phase with $C222_1$ symmetry and nearly iden...

  20. The use of radioactive cysteine methyl ester for labeling glycosylated molecules oxidized by periodate or neuraminidase plus galactose oxidase

    International Nuclear Information System (INIS)

    Treatment of rat lymph node cells with periodate or neuraminidase plus galactose oxidase initiates blast transformation and cell division of T lymphocytes. Either treatment introduces aldehyde functions onto glycosylated molecules of the plasma membrane. Reduction of the aldehydes with borohydride leads to a concentration-dependent inhibition of the mitogenic response. Cysteine methyl ester (Cys(Me], which can form a stable thiazolidine adduct with aldehydes, also inhibits mitogenesis in a concentration-dependent manner. Maximum inhibition is achieved at Cys(Me) concentrations about 10-fold lower than those required for borohydride (0.4 and 5 mM, respectively). [35S]Cys(Me) has been synthesized and compared with [3H]borohydride as a labeling reagent for molecules on the plasma membrane oxidized by periodate or neuraminidase plus galactose oxidase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of labeled whole cell lysates or of crude membrane fractions prepared from labeled cells revealed that the same oxidized molecules are specifically labeled with both reagents. Homogenates of cells labeled with either radioactive reagent were fractionated by differential and isopycnic centrifugation. The fractions were analyzed for radioactivity and for a number of marker constituents localized in various subcellular organelles. Following treatment with either reagent, the radioactivity that was covalently incorporated into macromolecules was primarily associated with sedimentable components that distributed among the fractions like plasma membrane markers. When compared with [3H]borohydride, Cys(Me) offers several advantages as a surface labeling reagent for glycosylated plasma membrane molecules, chiefly the possibility of preparing reagents labeled with isotopes other than tritium, including those like 35S, which are much stronger radioactive emitters

  1. Etude de l'anode pour la pile à combustible directe aux borohydrures

    OpenAIRE

    Olu, Pierre-Yves

    2015-01-01

    The present work focuses on direct borohydride fuel cell (DBFC) anodes. A first approach to develop a suitable anode design for the DBFC consists in the study of the anode within the real DBFC system. In that frame, carbon-supported platinum and palladium nanoparticles are characterized and compared as anode electrocatalyst in DBFC configuration. Other variables such as the morphology of the anode and the stability of the catalyst nanoparticles are considered.The ideal DBFC anode catalyst sho...

  2. Synthesis of octitols and the respective amino-derivatives from 'organo-aldols'.

    Science.gov (United States)

    Łęczycka, Katarzyna; Chaciak, Bartosz; Cieplak, Maciej; Cmoch, Piotr; Jarosz, Sławomir

    2015-02-11

    Two diastereoisomeric keto-octoses, obtained in the reaction of 2,3:4,5-diacetone-D-arabinose with protected dihydroxyacetone catalyzed with L- or D-proline, were converted into octitols by stereoselective reduction of the carbonyl group with zinc borohydride and final deprotection. The study on the preparation of the respective amino-derivatives by reductive amination of these organo-adducts is presented; stereochemical aspects of these processes are discussed. PMID:25130931

  3. Tritium (3H) radiolabeling of protein A and antibody to high specific activity: Application to cell surface antigen radioimmunoassays

    International Nuclear Information System (INIS)

    Staphylococcal protein A and several different immunoglobulins have been radiolabeled to high specific activities (> 106 cpm/μg) by reductive methylation with tritiated (3H) sodium borohydride. The proteins retain excellent functional and antigenic properties. The utility of these reagents in a variety of assays for cell surface antigens is illustrated. The results indicate that this radiolabeling procedure may become the method of choice for many cell surface and solution immunoassays. (Auth.)

  4. Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B2: Catalytic Polymerisation of Aniline and Pyrrole

    OpenAIRE

    Mallikarjuna N. Nadagouda; Varma, Rajender S.

    2008-01-01

    For the first time, we report green chemistry approach using vitamin B2 in the synthesis of silver (Ag) and palladium (Pd), nanospheres, nanowires, and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride (NaBH4) or hydroxylamine hydrochloride and any special capping or dispersing agent. Vitamin B2 was used as reducing agent as well as capping agent due to its high-water solubility, biodegradability, and low-toxicity compared with other reducing a...

  5. Structural Characterization and Mechanical Properties of As-plated and Heat Treated Electroless Ni-B-P Alloy Coatings

    Directory of Open Access Journals (Sweden)

    P. G. Venkatakrishnan

    2014-05-01

    Full Text Available The Ni-B-P alloy coatings were made autocatalytically (electroless using an alkaline plating bath with nickel chloride hexahydrate (NiCl2.6H2O as the source of nickel ions, sodium borohydride (NaBH4 and sodium hypophosphite (NaH2PO2 as reducing agents and source of boron and phosphorous ions, respectively. The effects of bath concentrations on the plating rate, composition of coating, surface morphology, structural features and microhardness have been studied by varying NaBH4 concentration in the plating bath from 0.2 to 0.8 g/l while keeping NaH2PO2 concentration constant (12 g/l. The plating rate and boron content of the electroless Ni-B-P ternary alloy coatings increased with increasing NaBH4 concentration in the plating bath. The scanning electron microscopic images revealed that the morphology of the coating changed from corn cob structure to coarse cauliflower structure with increasing borohydride concentration in the plating bath. Broadening of X-ray diffraction peak is observed, as the borohydride concentration is increased in the plating bath, which is attributed to the large reduction in the crystallite size of the Ni-B-P alloy coatings. The microhardness values of the coating increased with increasing borohydride concentration in the plating bath. The as-plated Ni-B-P alloy coating containing higher boron content (3.2 wt% shows higher hardness of 700 HV compared to other Ni-B-P alloy coatings. The XRD patterns of heat treated Ni-B-P alloy coatings (500 °C show Ni3B intermetallic peaks along with Ni peaks. The presence of Ni3B intermetallic compound significantly increases the microhardness values of the heat treated Ni-B-P alloy coatings.

  6. Synthesis of Ca(BH4)2 from Synthetic Colemanite Used in Hydrogen Storage by Mechanochemical Reaction

    Science.gov (United States)

    Karabulut, Ahmet F.; Guru, Metin; Boynueğri, Tuğba A.; Aydin, Mustafa Yasir

    2016-08-01

    In this study, synthesis of Ca(BH4)2 has been carried out with a solid phase reaction in which synthetic colemanite has been used as a raw material. Three dimensional high energy spex collider was selected for this mechanochemical reaction. Calcium borohydride is one of the most valuable metal borohydrides. In order to produce calcium borohydride economically, anhydrous colemanite mineral has been used as reactant. Calcium borohydride has been directly manufactured from anhydrous colemanite in spex-type ball milling without the need for any intermediate product. Thus, the advantages of this method over wet chemical procedure (such as having no intermediate product, no azeotropic limitations and no need of regaining product from solution after production by using evaporation, crystallization and drying processes) have made it possible to achieve the desired economical gains. Parametric experiments were conducted to determine the best conditions for the highest yield of solid phase reaction in the spex-type ball milling. Best results have been determined by using areas of related peaks in spectra of Fourier transform infrared spectroscopy (FT-IR). In order to use peaks area for determining Ca(BH4)2 concentration, a calibration graph of FT-IR absorbance peak areas has been created by using samples with known different concentrations of commercial Ca(BH4)2. Optimum amounts of calcium hydride and synthesis reaction time were found to be 2.1 times the stoichiometric ratio and 2500 min, respectively. As a result of these optimizations, the maximum yield of the solid phase reaction carried out by the spex-type ball milling has been determined as 93%.

  7. Computational modelling of structure and dynamics in lightweight hydrides

    OpenAIRE

    Aeberhard, Philippe C.; David, William I. F.; Edwards, Peter P.

    2012-01-01

    Hydrogen storage in lightweight hydrides continues to attract significant interest as the lack of a safe and efficient storage of hydrogen remains the major technological barrier to the widespread use of hydrogen as a fuel. The metal borohydrides Ca(BH₄)₂ and LiBH₄ form the subject of this thesis; three aspects of considerable academic interest were investigated by density functional theory (DFT) and molecular dynamics (MD) modelling. (i) High-pressure crystal structures of Ca(BH₄)₂ were pred...

  8. Camphor-mediated synthesis of carbon nanoparticles, graphitic shell encapsulated carbon nanocubes and carbon dots for bioimaging

    OpenAIRE

    Goldie Oza; Ravichandran, M.; Victor-Ishrayelu Merupo; Sachin Shinde; Ashmi Mewada; Jose Tapia Ramirez; Velumani, S.; Madhuri Sharon; Maheshwar Sharon

    2016-01-01

    A green method for an efficient synthesis of water-soluble carbon nanoparticles (CNPs), graphitic shell encapsulated carbon nanocubes (CNCs), Carbon dots (CDs) using Camphor (Cinnamomum camphora) is demonstrated. Here, we describe a competent molecular fusion and fission route for step-wise synthesis of CDs. Camphor on acidification and carbonization forms CNPs, which on alkaline hydrolysis form CNCs that are encapsulated by thick graphitic layers and on further reduction by sodium borohydrid...

  9. Comparing and Optimizing Nitrate Adsorption from Aqueous Solution Using Fe/Pt Bimetallic Nanoparticles and Anion Exchange Resins

    OpenAIRE

    Muhammad Daud; Zahiruddin Khan; Aisha Ashgar; M. Ihsan Danish; Ishtiaq A. Qazi

    2015-01-01

    This research work was carried out for the removal of nitrate from raw water for a drinking water supply. Nitrate is a widespread ground water contaminant. Methodology employed in this study included adsorption on metal based nanoparticles and ion exchange using anionic resins. Fe/Pt bimetallic nanoparticles were prepared in the laboratory, by the reduction of their respective salts using sodium borohydride. Scanning electron microscope, X-ray diffraction, energy dispersive spectrometry, and ...

  10. Synthesis of graphene platelets by chemical and electrochemical route

    International Nuclear Information System (INIS)

    Graphical abstract: A schematic showing the overall reduction process of graphite to reduced graphene platelets by chemical and electrochemical route. - Highlights: • Graphene was prepared by diverse routes viz. chemical and electrochemical methods. • NaBH4 was effective for removing oxygen functional groups from graphene oxide. • Sodium borohydride reduced graphene oxide (SRGO) showed high specific capacitance. • Electrochemical rendered a cheap route for production of graphene in powder form. - Abstract: Graphene platelets were synthesized from graphene oxide by chemical and electrochemical route. Under the chemical method, sodium borohydride and hydrazine chloride were used as reductants to produce graphene. In this paper, a novel and cost effective electrochemical method, which can simplify the process of reduction on a larger scale, is demonstrated. The electrochemical method proposed in this paper produces graphene in powder form with good yield. The atomic force microscopic images confirmed that the graphene samples prepared by all the routes have multilayers of graphene. The electrochemical process provided a new route to make relatively larger area graphene sheets, which will have interest for further patterning applications. Attempt was made to quantify the quantum of reduction using cyclic voltammetry and choronopotentiometry techniques on reduced graphene samples. As a measure in reading the specific capacitance values, a maximum specific capacitance value of 265.3 F/g was obtained in sodium borohydride reduced graphene oxide

  11. Increasing Hydrogen Density with the Cation-Anion Pair BH4−-NH4+ in Perovskite-Type NH4Ca(BH43

    Directory of Open Access Journals (Sweden)

    Pascal Schouwink

    2015-08-01

    Full Text Available A novel metal borohydride ammonia-borane complex Ca(BH42·NH3BH3 is characterized as the decomposition product of the recently reported perovskite-type metal borohydride NH4Ca(BH43, suggesting that ammonium-based metal borohydrides release hydrogen gas via ammonia-borane-complexes. For the first time the concept of proton-hydride interactions to promote hydrogen release is applied to a cation-anion pair in a complex metal hydride. NH4Ca(BH43 is prepared mechanochemically from Ca(BH42 and NH4Cl as well as NH4BH4 following two different protocols, where the synthesis procedures are modified in the latter to solvent-based ball-milling using diethyl ether to maximize the phase yield in chlorine-free samples. During decomposition of NH4Ca(BH43 pure H2 is released, prior to the decomposition of the complex to its constituents. As opposed to a previously reported adduct between Ca(BH42 and NH3BH3, the present complex is described as NH3BH3-stuffed α-Ca(BH42.

  12. Reductive demercuration of hex-5-enyl-1-mercuric bromide by metal hydrides. Rearrangement, isotope effects, and mechanism

    International Nuclear Information System (INIS)

    The use of the rearrangement of hex-5-enyl radical intermediates as a mechanistic probe has been examined in the reductive demercurations of hex-5-enyl-l-mercuric bromide (1). Methylcyclopentane and 1-hexene are the major products from reductions of 1 by sodium borohydride, lithium aluminum hydride, and tri-n-butyltin hydride. The formation of methylcyclopentane and the absence of cyclohexane are consistent with a noncage, free-radical chain mechanism for these reductions. The sodium amalgam reduction of 1 produces only 1-hexene. Hex-5-en-l-ol and a peroxide are formed from sodium borohydride reductions of 1 in the presence of molecular oxygen. Isotope effects for transfer of hydrogen to the intermediate hex-5-enyl radicals have been determined from the 1-hexene/methylcyclopentane product ratio, since rearrangement of the 5-hexenyl radical competes with hydrogen abstraction. The magnitude of these isotope effects (1.8 +- 0.2) is the same for reductive demercurations of 1 by sodium borohydride, lithium aluminum hydride, and tri-n-butyltin hydride; these results provide evidence for a common hydrogen-transfer agent, such as hex-5-enyl-1-mercuric hydride, for all of these metal-hydride reductions. The validity of the competing rearrangement method of determining hydrogen isotope effects has been demonstrated by determining the isotope effect for the tri-n-butyltin hydride reduction of 6-bromo-1-hexene (2.8 +- 0.2) at 400C

  13. Synthesis and properties of copper nanoparticles stabilized by polyethylene glycol

    International Nuclear Information System (INIS)

    The composite nanoparticles containing metallic copper and copper (I) oxide were synthesized by reduction of copper sulfate with sodium borohydride in the presence of polyethylene glycol. The effect of reactant ratio and reaction time on the morphology and phase composition of the obtained nanoparticles was investigated by transmission electron microscopy and X-ray phase analysis. It was shown that the factor which most greatly influences the particle size is the content of polyethylene glycol (PEG) in the reaction mixture – with increasing PEG content average particle size determined by transmission electron microscopy, reduced from 22,0 to 14,0 nm. The reaction time and the ratio of copper sulfate and sodium borohydride have small effect on the average size and coherent scattering dimensions of nanoparticles formed. In accordance with the results of X-ray phase analysis in all cases the biphasic particles containing metallic copper and copper oxide (I) formed regardless of reaction condition. The relative content of Cu2O in samples varies from 11,5 to 44,1 wt. %. Among the samples obtained and researched the sample prepared at an equimolar ratio of copper sulfate and sodium borohydride has a special place. It is characterized by a high content of copper oxide (I), a bimodal distribution of particle size and the largest average particle size. (authors)

  14. Studies on the solubilization of the water-insoluble fraction from human lens and cataract.

    Science.gov (United States)

    Ortwerth, B J; Olesen, P R

    1992-12-01

    Studies were carried out comparing the ability of urea extraction and sonication to solubilize the water-insoluble (WI) protein fraction from human lens tissue. Sonication and urea extraction were able to solubilize greater than 80% of the insoluble protein whether whole lenses or lens nuclei were used. This was true for normal lens and +1 cataracts; however, only 60% solubilization was obtained with the WI fraction from more advanced cataracts. Equal aliquots of a WI fraction from both pooled normal and pooled cataract lens nuclei were solubilized with and without reducing agents. The addition of dithiothreitol (DTT) had no significant effect on solubilization of the normal lens WI fraction. DTT did increase the protein solubilized from the cataract WI fraction by 30% with urea extraction; however, no increase was seen with sonication. When sodium borohydride was used as the reducing agent, essentially the same results were obtained. The solubilized protein populations were identical by SDS-PAGE and amino acid analysis. The addition of reducing agents had no effect on the amino acid content of the solubilized proteins with the single exception of lysine. This amino acid was markedly decreased in the proteins extracted in the presence of 40 mM sodium borohydride, but not with DTT. These data suggest that the borohydride not only increased the amount of protein solubilized, but likely also stabilized glycated lysine residues during the acid hydrolysis. Therefore, sonication readily provides a soluble preparation of the WI proteins from normal and cataract lens nuclei without the need for denaturing agents, however, disulfide-linked and lysine modified crystallins were best solubilized with urea. PMID:1486936

  15. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    OpenAIRE

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-01-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO na...

  16. Caffeic acid: potential applications in nanotechnology as a green reducing agent for sustainable synthesis of gold nanoparticles.

    Science.gov (United States)

    Seo, Yu Seon; Cha, Song-Hyun; Yoon, Hye-Ran; Kang, Young-Hwa; Park, Youmie

    2015-04-01

    The sustainable synthesis of gold nanoparticles from gold ions was conducted with caffeic acid as a green reducing agent. The formation of gold nanoparticles was confirmed by spectroscopic and microscopic methods. Spherical nanoparticles with an average diameter of 29.99 ± 7.43 nm were observed in high- resolution transmission electron microscopy and atomic force microscopy images. The newly prepared gold nanoparticles exhibited catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. This system enables the preparation of green catalysts using plant natural products as reducing agents, which fulfills the growing need for sustainability initiatives. PMID:25973494

  17. Development of novel catalytically active polymer-metal-nanocomposites based on activated foams and textile fibers

    Science.gov (United States)

    Domènech, Berta; Ziegler, Kharla K.; Carrillo, Fernando; Muñoz, Maria; Muraviev, Dimitri N.; Macanás, Jorge

    2013-05-01

    In this paper, we report the intermatrix synthesis of Ag nanoparticles in different polymeric matrices such as polyurethane foams and polyacrylonitrile or polyamide fibers. To apply this technique, the polymer must bear functional groups able to bind and retain the nanoparticle ion precursors while ions should diffuse through the matrix. Taking into account the nature of some of the chosen matrices, it was essential to try to activate the support material to obtain an acceptable value of ion exchange capacity. To evaluate the catalytic activity of the developed nanocomposites, a model catalytic reaction was carried out in batch experiments: the reduction of p-nitrophenol by sodium borohydride.

  18. STABILIZATION OF UNUSUAL SUBSTRATE COORDINATION MODES IN DINUCLEAR MACROCYCLIC COMPLEXES

    Directory of Open Access Journals (Sweden)

    Vasile Lozan

    2010-06-01

    Full Text Available The steric protection offered by the macrobinucleating hexaazaditiophenolate ligand (L allows for the preparation of the first stable dinuclear nickel(II borohydride bridged complex, which reacts rapidly with elemental sulphur producing a tetranuclear nickel(II complex [{(LNi2}2(μ-S6]2+ bearing a helical μ4-hexa- sulfide ligand. The [(LCoII 2]2+ fragment have been able to trap a monomethyl orthomolybdate in the binding pocket. Unusual coordination modes of substrate in dinuclear macrocyclic compounds was demonstrated.

  19. Synthesis of carbasugars from aldonolactones. Part II. Preparation of polyhydroxy/aminocyclopentanes functionalised at all five carbons

    DEFF Research Database (Denmark)

    Lundt, Inge; Johansen, Steen Karsk

    Starting from (1R,5R,8R)-8-acetoxy-2-oxabicyclo[3.3.0]oct-6-en-3-one (4) the syntheses of 4a(R)-hydroxy-5-deoxycarba--L-xylo-hexofuranose (17), 4a(S)-hydroxy-5-deoxycarba--L-xylo-hexofuranose (21), 4a(S)-hydroxy-5-deoxycarba--L-xylo-hexofuranose (23) and 4a(R)-hydroxy-1-amino-1,5-dideoxycarba-......--L-xylo-hexofur anose (1) have been achieved. The methodology included OsO4 catalysed dihydroxylation as well as regioselective epoxide opening followed by calcium borohydride reduction of the lactone moiety....

  20. 低分子量壳聚糖及其衍生物与金属离子配合物研究%Coordination Compounds of Metal Ions with Low-molecular Weight Chitosan and Their Derivative

    Institute of Scientific and Technical Information of China (English)

    丁德润

    2005-01-01

    Chitosan(CTS) of molecular weight 3 × 106 was degraded by oxidation with H2O2. The molecular weight of degraded chitosan (CTS′) was between 5 500-6 000. Through the reaction of degraded chitosan with glyoxylic acid and sodium borohydride, the modified derivative of N-Carboxymethyl degraded chitosan (NCTS′) was obtained. The metal ions of Fe(Ⅱ), Ni(Ⅱ), Cu(Ⅱ) and Cr(Ⅲ) were coordinated at different conditions by degraded chitosan(CTS′→ M(Ⅱ)) and its derivative (NCTS′→ M(Ⅱ))). These coordination compounds were characterized with UV and IR spectroscopy.

  1. Platinium Nanoparticles Deposited on Oxygen-Containing Functional Groups at Carbon Vulcane XC-72 as a Cathode Catalyst for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Sajjad; Sadaghat; Sharehjini; Ahmad; Nozad; Golikand; Mohammad; Yari

    2007-01-01

    1 Results Surface oxidized carbon vulcane XC-72 as catalyst support, prepared by chemically anchoring Pt onto the surface modified carbon vulcane XC-72. The nanoparticles of Pt are synthesized by reduction of H2PtCl6 with sodium borohydride in a 5.5 buffer solution of sodium citrate, the complexation of citrate with metal ions is beneficial to the formation of nanoparticles. For comparison, an electrode is prepared by E-Tek Pt/C 20 Wt% with a typical Pt loading of 50 μg·cm-2, that shows higher specifi...

  2. New Synthesis of Pt-Ru Nanoparticles on Surface Modified Carbon Vulcane XC-72 as an Effective Catalyst for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Ahmad; Nozad; Golikand; Sajjad; Sadaghat; Sharehjini; Mohammad; Yari

    2007-01-01

    1 Results Pt-Ru nanoparticles are synthesised on the surface oxidized carbon Vulcane XC-72 as catalyst support by chemically anchoring Pt and Ru onto the surface of modified carbon vulcane XC-72 (by refluxing in 70% HNO3 at 120 ℃ for 12 h to introduce surface functional groups) .The nanoparticles of Pt and Ru are synthesized by reduction of H2PtCl6 and K4Ru(CN)6 with sodium borohydride in a 5.5 buffer solution of sodium citrate,the complexation of citrate with metal ions is beneficial to the formati...

  3. Chemically Synthesised Pt Particles on Surface Oxidized Carbon Nanotubes as an Effective Catalyst for Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Mohammad; yari; Sajjad; Sadaghat; Sharehjini

    2007-01-01

    1 Results The synthesis, physical characterization and electrochemical analysis of Pt particles prepared using the surface oxidized carbon nanotubes prepared by chemically anchoring Pt onto the surface of the CNTs with 2.0 mol/L HNO3 by refluxing for 10 h to introduce surface functional groups.The particles of Pt are synthesized by reduction with sodium borohydride of H2PtCl6. The electro-oxidation of liquid methanol of this catalyst as a thin layer on glassy carbon electrode is investigated at room te...

  4. Highly dispersed Pd nanoparticles on chemically modified graphene with aminophenyl groups for formic acid oxidation

    Institute of Scientific and Technical Information of China (English)

    Yang Su-Dong; Shen Cheng-Min; Tong Hao; He Wei; Zhang Xiao-Gang; Gao Hong-Jun

    2011-01-01

    A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine.Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction.The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts.

  5. Reversibility of Al/Ti Modified LiBH4

    DEFF Research Database (Denmark)

    Blanchard, Didier; Shi, Qing; Boothroyd, Chris;

    2009-01-01

    Lithium borohydride has a high reversible hydrogen storage capacity. For its practical use as an on-board hydrogen storage medium in mobile applications, the temperature and pressure conditions along with the kinetics of the hydrogenation/dehydrogenation cycles have to be improved. Lithium...... dehydrogenated state and disappears in the hydrogenated state; its formation increases the stability of the products and thus results in a lower desorption temperature. The Al−Ti (ss) also allows a slow release of hydrogen at very low temperatures (200 °C)....

  6. Thermal Decomposition of Anhydrous Alkali Metal Dodecaborates M2B12H12 (M = Li, Na, K)

    OpenAIRE

    Liqing He; Hai-Wen Li; Etsuo Akiba

    2015-01-01

    Metal dodecaborates M2/nB12H12 are regarded as the dehydrogenation intermediates of metal borohydrides M(BH4)n that are expected to be high density hydrogen storage materials. In this work, thermal decomposition processes of anhydrous alkali metal dodecaborates M2B12H12 (M = Li, Na, K) synthesized by sintering of MBH4 (M = Li, Na, K) and B10H14 have been systematically investigated in order to understand its role in the dehydrogenation of M(BH4)n. Thermal decomposition of M2B12H12 indicates m...

  7. Low-temperature approach to synthesize iron nitride from amorphous iron.

    Science.gov (United States)

    Han, Yi; Wang, Huamin; Zhang, Minghui; Su, Ming; Li, Wei; Tao, Keyi

    2008-02-18

    Iron nitride was prepared by a nitridation reaction in NH 3 using amorphous iron as precursor. The precursor was prepared at ambient temperature through the process of reducing ferrous sulfate by potassium borohydride, followed by the nitridation at different temperatures. The nitridation reaction occurred at 548 K, and -Fe 2-3N was formed at 573 K. The reaction temperature was much lower than that using crystallized iron because of the characteristics of the amorphous materials. The existence of a small quantity of boron (1.6 wt.%) improved the stability of the amorphous precursor, which guaranteed an amorphous iron precursor at nitriding temperatures in excess of 548 K. PMID:18198828

  8. Feasibility study of the determination of selenium in mineral water by ICPOES using NOVA-2 dual-flow ultrasonic nebulizer and direct hydride generation

    International Nuclear Information System (INIS)

    Full text: A new hydride generator has been explored for the introduction of the sample into ICPOES with radial viewing. The acidic sample and the borohydride solution are delivered by the dual-flow system of a commercial NOVA-2 ultrasonic nebulizer and mixed in the spray chamber. The analytical figures of merit for the determination of As, Sb and Se were evaluated. Results showed that the analytical performance of the new system was superior to that of conventional nebulization systems, including the susceptibility to non-spectroscopic interferences produced by transition metals. The utility of the system was demonstrated in the determination of Se in mineral water. (author)

  9. Ultra-Thin Films of Poly(acrylic acid)/Silver Nanocomposite Coatings for Antimicrobial Applications

    OpenAIRE

    Alaa Fahmy; Eisa, Wael H.; Mohamed Yosef; Ali Hassan

    2016-01-01

    In this work not only colloids of poly(acrylic acid) (PAA) embedded with silver nanoparticles (Ag-NPs) but thin films (10 nm) also were deposited using electrospray deposition technique (ESD). A mixture of sodium borohydride (NaBH4) and ascorbic acid (AA) were utilized to reduce the silver ions to generate Ag-NPs in the PAA matrix. Moreover, sodium tricitrate was used to stabilize the prepared colloids. The obtained colloids and films were characterized using UV-visible, transmission electron...

  10. Structural Characterization and Mechanical Properties of As-plated and Heat Treated Electroless Ni-B-P Alloy Coatings

    OpenAIRE

    P. G. Venkatakrishnan; S. S. Mohamed Nazirudeen; T.S.N. Sankara Narayanan

    2014-01-01

    The Ni-B-P alloy coatings were made autocatalytically (electroless) using an alkaline plating bath with nickel chloride hexahydrate (NiCl2.6H2O) as the source of nickel ions, sodium borohydride (NaBH4) and sodium hypophosphite (NaH2PO2) as reducing agents and source of boron and phosphorous ions, respectively. The effects of bath concentrations on the plating rate, composition of coating, surface morphology, structural features and microhardness have been studied by varying NaBH4 concentra...

  11. Electroless Ni-B-W coatings for improving hardness, wear and corrosion resistance: Nanašanje Ni-B-W s cementacijskim galvaniziranjem za izboljšavo trdote, obrabe in odpornosti proti koroziji:

    OpenAIRE

    Aydeniz, Ali Imre; Calli, Cagdas; Dil, Gökce; Göksenli, Ali; MUHAFFEL, Faiz; Yüksel, Behiye

    2013-01-01

    In this study the formation of a Ni-B-W coating on steel using an electroless plating process and evaluation of the hardness, wear and corrosion resistance was analyzed. The Ni-B-W coating was prepared using an alkaline borohydride-reduced electroless nickel bath. Scanning electron microscopy (SEM) of the cross-sectional view of the Ni-B-W coating was analyzed and the layer characteristics were investigated. The Ni-B-W coating was characterized using XRD. The study reveals that the Ni-B-W coa...

  12. Morphology Analysis of Nickel-boron/ diamond Electroless Deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Lin; ZHU Xuanmin; ZHOU Jian; OUYANG Shixi

    2008-01-01

    The influences of mass concentration of nickel chloride hexahydrate, sodium borohydride,ethylenediamine, pH value, bath temperature on deposition rate were studied with orthogonal experiments by a series of pre-treatments on micro-diamond particle, and the optimized parameters were obtained. Both the morphology and the composition of original diamond and the diamond with Ni-B coating were analyzed by SEM and XRD respectively. The SEM image shows that the spherical Ni-B particle is coated upon diamond.XRD pattern shows that the coating compositions are Ni and Ni2B.

  13. Cob(I)alamin Reacts with Sucralose to Afford an Alkylcobalamin : Relevance to In Vivo Cobalamin and Sucralose Interaction

    OpenAIRE

    Motwani V, Hitesh; Qiu, Shiran; Golding, Bernard T.; Kylin, Henrik; Törnqvist, Margareta

    2011-01-01

    Vitamin B12, viz., cyano- or hydroxo-cobalamin, can be chemically or enzymatically converted into the derivatives methyl- and adenosyl-cobalamin, which are complex organometallic cofactors associated with several cobalamin-dependent enzymes. The reduced form of vitamin B12, cob(I)alamin {Cbl(I)}, obtained by reduction of hydroxocobalamin (OH-Cbl) with e.g. sodium borohydride, is one of the most powerful nucleophiles known. Cbl(I) was shown to react readily with the synthetic sweetener sucralo...

  14. Synthesis and Characterization of Nanostructured Fe-Ni Alloy Whisker

    Institute of Scientific and Technical Information of China (English)

    DONG Guo-jun; WANG Gui-xiang; ZHANG Mi-lin; LI Ru-Min; WANG Jun

    2002-01-01

    The nanocrystalline γ-(Fe,Ni) alloy whiskers have been prepared by chemical reduction of Fe2+ and Ni2+ ions with potassium borohydride under the function of a dispersant agent PE followed by heat treatment at 600℃ under the protection of nitrogen.Conditions, such as quantity of NaOH, concentration of salts, and species of surfactants, of preparation of Fe-Ni alloy have been discussed. X-ray diffraction(XRD), transmission electron microscopy(TEM) and vibrating sample magnetometer(VSM) characterized the synthesized Fe-Ni alloy. Character, capability and use of the materials have been summarized.

  15. Solid hydrides as hydrogen storage reservoirs

    International Nuclear Information System (INIS)

    Metal hydrides as hydrogen storage materials are briefly reviewed in this paper. Fundamental properties of metal-hydrogen (gas) system such as Pressure-Composition-Temperature (P-C-T) characteristics are discussed on the light of the metal-hydride thermodynamics. Attention is specially paid to light metal hydrides which might have application in the car and transport sector. The pros and cons of MgH2 as a light material are outlined. Researches in course oriented to improve the behaviour of MgH2 are presented. Finally, other very promising alternative materials such as Al compounds (alanates) or borohydrides as light hydrogen accumulators are also considered. (Author)

  16. Complex hydrides for hydrogen storage – new perspectives

    Directory of Open Access Journals (Sweden)

    Morten B. Ley

    2014-04-01

    Full Text Available Since the 1970s, hydrogen has been considered as a possible energy carrier for the storage of renewable energy. The main focus has been on addressing the ultimate challenge: developing an environmentally friendly successor for gasoline. This very ambitious goal has not yet been fully reached, as discussed in this review, but a range of new lightweight hydrogen-containing materials has been discovered with fascinating properties. State-of-the-art and future perspectives for hydrogen-containing solids will be discussed, with a focus on metal borohydrides, which reveal significant structural flexibility and may have a range of new interesting properties combined with very high hydrogen densities.

  17. Nanoconfined LiBH4 as a Fast Lithium Ion Conductor

    DEFF Research Database (Denmark)

    Blanchard, Didier; Nale, Angeloclaudio; Sveinbjörnsson, Dadi Þorsteinn;

    2015-01-01

    Designing new functional materials is crucial for the development of efficient energy storage and conversion devices such as all solid-state batteries. LiBH 4 is a promising solid electrolyte for Li-ion batteries. It displays high lithium mobility, although only above 110 °C at which a transition...... mobility is associated with a fraction of the confined borohydride that shows no phase transition, and most likely located close to the interface with the SiO2 pore walls. These results point to a new strategy to design low-temperature ion conducting solids for application in all solid-state lithium ion...

  18. Size control in the synthesis of 1–6 nm gold nanoparticles using folic acid-chitosan conjugate as a stabilizer

    International Nuclear Information System (INIS)

    We report a simple and practical method for the preparation of folic acid (FA)-chitosan functionalized gold nanoparticles (AuNPs) with a very small size (1–6 nm). Sodium borohydride was used as a reducing agent. The size of the AuNPs was controlled by adjusting the mass fraction of FA-chitosan conjugate to Au. The AuNPs were characterized using UV–vis spectroscopy and transmission electron microscopy (TEM). The results indicated that the size distribution of AuNPs decreased ranging from 6 nm to 1 nm with increasing the fraction of FA-chitosan conjugate in the reaction systems. (paper)

  19. Synthesis of 1,2[3H]-1,2-epoxy analogue of fructose-6P, an affinity label of Escherichia coli glucosamine-6P synthase

    International Nuclear Information System (INIS)

    1,2-anhydroglucitol-6P, a known inhibitor of glucose-6P isomerase, behaved as a fructose-6P site-directed irreversible inhibitor of bacterial glucosamine-6P synthase. The lack of reproducibility of the aldolase-mediated condensation of dihydroxyacetone phosphate and glycidaldehyde followed by borohydride reduction previously described prompted us to develop a chemical route to this compounds and its radiolabelled counterpart. The compound was synthesized in 13 steps from D-arabinose with a 6% overall yield. Tritium introduction was performed at step 11 (3 → 4) allowing isolation of the title compound of high specific radioactivity. (author)

  20. Green coconut ( Cocos nucifera Linn) shell extract mediated size controlled green synthesis of polyshaped gold nanoparticles and its application in catalysis

    Science.gov (United States)

    Paul, Koushik; Bag, Braja Gopal; Samanta, Kousik

    2014-08-01

    The shell extract of green coconut ( Cocos nucifera Linn) has been utilized for the synthesis of gold nanoparticles at room temperature under very mild condition without any extra stabilizing or capping agents. The size of the synthesized gold nanoparticles could be controlled by varying the concentration of the shell extract. The stabilized gold nanoparticles were analyzed by surface plasmon resonance spectroscopy, HRTEM, Energy dispersive X-ray spectroscopy and X-ray diffraction studies. The catalytic activity of the freshly synthesized gold nanoparticles was studied for the sodium borohydride reduction of 4-nitrophenol and the kinetics of the reduction reaction were studied spectrophotometrically.

  1. Determination of Trace Germanium in Marine Sediments by Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS)

    Institute of Scientific and Technical Information of China (English)

    LI Jing; ZHAO Shilan; ZHANG Zhaohui; ZENG Xianjie

    2004-01-01

    A method for the analysis of trace germanium in marine sediments by HG-AFS has been investigated. The experimental conditions such as the acidity of reduction reaction, the amount of sodium boro-hydride, the carrier gas flow rate, etc., were tested and optimized by using a kind of orthogonal design. The detection limit of the presented method is 0.95 μg L-1 for germanium. The calibration curve shows a satisfactory line in the concentration range 0-320 μg L-1 Ge with a variation coefficient of ±2.1%.

  2. Effects of the addition of an organic polymer on the hydrolysis of sodium tetrahydroborate in batch reactors

    OpenAIRE

    M. J. F. Ferreira; Fernandes, V. R.; Gales, L.; Rangel, C. M.; Pinto, A. M. F. R.

    2010-01-01

    An experimental study is presented both on the generation and storage of molecular hydrogen (H2) by small additions of an organic polymer - carboxymethyl cellulose (CMC) - to sodium borohydride (NaBH4) through the alkaline hydrolysis, in the presence of a powdered nickel-ruthenium based catalyst reused from 274 to 282 times. The experiments were performed at 45 °C in two batch reactors with internal volumes of 0.229 L and 0.369 L, made of stainless-steel with bottom conical shape, positioned ...

  3. MAGNETIC POLYMER MICROSPHERE STABILIZED GOLD NANOCOLLOIDS AS A FACILELY RECOVERABLE CATALYST

    Institute of Scientific and Technical Information of China (English)

    Han Zhang; Xin-lin Yang

    2011-01-01

    Magnetically responsive hierarchical magnetite/silica/poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (Fe3O4/SiO2/P(EGDMA-co-VPy)) tri-layer microspheres were used as stabilizers for gold metallic nanocolloids as a facilely recoverable catalyst with the reduction of 4-nitrophenol to 4-aminophenol as a model reaction. The magnetic microsphere stabilized gold metallic nanocolloids were prepared by in situ reduction of gold chloride trihydrate with borohydride as reductant via the stabilization effect of the pyridyl groups to gold nanoparticles on the surface of the outer shell-layer of the inorganic/polymer fri-layer microspheres.

  4. Apurinic/apyrimidinic (AP) site recognition by the 5′-dRP/AP lyase in poly(ADP-ribose) polymerase-1 (PARP-1)

    OpenAIRE

    Khodyreva, S. N.; Prasad, R; Ilina, E. S.; Sukhanova, M. V.; Kutuzov, M. M.; Liu, Y.; Hou, E. W.; Wilson, S H; Lavrik, O. I.

    2010-01-01

    The capacity of human poly(ADP-ribose) polymerase-1 (PARP-1) to interact with intact apurinic/apyrimidinic (AP) sites in DNA has been demonstrated. In cell extracts, sodium borohydride reduction of the PARP-1/AP site DNA complex resulted in covalent cross-linking of PARP-1 to DNA; the identity of cross-linked PARP-1 was confirmed by mass spectrometry. Using purified human PARP-1, the specificity of PARP-1 binding to AP site-containing DNA was confirmed in competition binding experiments. PARP...

  5. A new efficient and stereospecific conversion of aminodeoxyalditols into aminoalkyl-substituted tetrahydrofurans

    DEFF Research Database (Denmark)

    Norrild, Jens Chr.; Pedersen, Christian; Defaye, Jacques

    1996-01-01

    Reaction of a series of aminodeoxy-pentitols and -hexitols in anhydrous hydrogen fluoride with formic acid as catalyst gave the corresponding 2,5- and 3,6-anhydro-anlinodeoxyalditols; namely, 1-amino-2,5-anhydro-1-deoxy-D-arabinitol, -D-xylitol, and -D-ribitol; 1-amino-3,6-anhydro-1-deoxy......-trimethylammonio-D-gulitol chloride. D-arabino-Hexosulose phenylosotriazole gave the corresponding 3,6-anhydro-D-avabino-hexosulose phenylosotriazole. Syntheses of the 1-amino-1-deoxyalditols were performed by reductive amination with benzylamine-sodium borohydride followed by catalytic hydrogenation over Pd-C. (C...

  6. Highly dispersed Pd nanoparticles on chemically modified graphene with aminophenyl groups for formic acid oxidation

    International Nuclear Information System (INIS)

    A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine. Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction. The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts. (atomic and molecular physics)

  7. Metil coenzima M redutase (MCR e o fator 430 (F430

    Directory of Open Access Journals (Sweden)

    Nakagaki Shirley

    2006-01-01

    Full Text Available This review presents studies on methyl coenzyme M reductase, the biological system Factor 430 (F430 and the use of nickel(II complexes as structural and functional models. The ability of F430 and nickel(II macrocycle complexes to mediate the reductive dehalogenation of cyclohexyl halogens and the CH3-S bond cleavage of methyl CoM (by sodium borohydride and some intermediate species proposed for the catalytic cycle of the biological system F430 was reviewed. The importance of the structure of the nickel complexes and the condition of the catalytic reduction reaction are also discussed.

  8. Metil coenzima M redutase (MCR e o fator 430 (F430

    Directory of Open Access Journals (Sweden)

    Shirley Nakagaki

    2006-10-01

    Full Text Available This review presents studies on methyl coenzyme M reductase, the biological system Factor 430 (F430 and the use of nickel(II complexes as structural and functional models. The ability of F430 and nickel(II macrocycle complexes to mediate the reductive dehalogenation of cyclohexyl halogens and the CH3-S bond cleavage of methyl CoM (by sodium borohydride and some intermediate species proposed for the catalytic cycle of the biological system F430 was reviewed. The importance of the structure of the nickel complexes and the condition of the catalytic reduction reaction are also discussed.

  9. Snythesis of 3-methy-1-lamino phenyl alcohol by microwave radiation%3-甲胺基-1-苯基丙醇的微波合成

    Institute of Scientific and Technical Information of China (English)

    吴海燕

    2012-01-01

    The synthesis method of 3- methylamino -1-phenyl acetone ( 1 )is acetophenone and methylamine hydrochloride, paraformaldehyde by microwave; The preparation 3- methylamino-1- phenylpropanol(2) is(l) reduction by sodium borohydride in methanol.%苯乙酮与甲胺盐酸盐、多聚甲醛用微波法合成3-甲胺基-1-苯基丙酮(1);(1)在甲醇中用硼氢化钠还原制备3-甲胺基-1-苯基丙醇(2).

  10. Preparation of Silver Nanostructures from Bicontinuous Microemulsions

    OpenAIRE

    Pedroza-Toscano, M. A.; Rabelero-Velasco, M.; Díaz de León, R.; H. Saade; R. G. López; E. Mendizábal; Puig, J. E.

    2012-01-01

    Precipitation of silver nanoparticles at 70°C was carried out by dosing a 1.3 M sodium borohydride aqueous solution over bicontinuous microemulsions formed with a mixture of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and sodium dodecylsulfate (SDS) as surfactants, a 0.5 M silver nitrate aqueous solution, and toluene. Weight ratios of 2.5/1 and 3/1 AOT/SDS were used in the precipitation reactions. Silver nanoparticles were characterized by transmission electronic microscopy, X-ray diffracti...

  11. Nanocomposite of montmorillonite and silver nanoparticles: Characterization and application in catalytic reduction of 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Praus, Petr, E-mail: petr.praus@vsb.cz [Department of Analytical Chemistry and Material Testing, VŠB-Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava-Poruba (Czech Republic); Turicová, Martina [Department of Analytical Chemistry and Material Testing, VŠB-Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava-Poruba (Czech Republic); Karlíková, Martina; Kvítek, Libor [Department of Physical Chemistry, Palacký University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Dvorský, Richard [Institute of Physics, VŠB-Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava-Poruba (Czech Republic)

    2013-07-15

    Silver ions previously intercalated into a montmorillonite (MMT) interlayer were reduced by sodium borohydride forming a nanocomposite of MMT and silver nanoparticles (Ag–MMT) with no other stabilizing additives. Within 360 min no coagulation of an aqueous Ag–MMT dispersion was observed. However, after 24 h the coagulation was indicated by a red shift of absorption maximum from 408 nm to 434 nm and by broadening of the absorbance band. The nanocomposite was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and measurements of specific surface area (SSA). It contained 4.94 wt. % of silver. Ag nanoparticles with an average size of 6.9 nm were located on the external MMT surface, mostly in its pores. Ag–MMT was used as a catalyst for reduction of 4-nitrophenol with sodium borohydride forming 4-aminophenol. After 30 s the reaction kinetics changed from zero order to first order, which was explained by means of the Langmuir–Hinshelwood model. The whole reduction was completed after 290 s. During this time min. 95 wt. % of Ag nanoparticles stayed fixed on the MMT support. - Highlights: • Ag nanoparticles with an average size of 6.9 nm were reduced on montmorillonite. • Ag nanoparticles were fixed in montmorillonite pores forming a stable nanocomposite. • Ag in the nanocomposite showed catalytic activity for reduction of 4-nitrophenol. • Reaction kinetics was explained by the Langmuir–Hinshelwood model.

  12. Nanocomposite of montmorillonite and silver nanoparticles: Characterization and application in catalytic reduction of 4-nitrophenol

    International Nuclear Information System (INIS)

    Silver ions previously intercalated into a montmorillonite (MMT) interlayer were reduced by sodium borohydride forming a nanocomposite of MMT and silver nanoparticles (Ag–MMT) with no other stabilizing additives. Within 360 min no coagulation of an aqueous Ag–MMT dispersion was observed. However, after 24 h the coagulation was indicated by a red shift of absorption maximum from 408 nm to 434 nm and by broadening of the absorbance band. The nanocomposite was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and measurements of specific surface area (SSA). It contained 4.94 wt. % of silver. Ag nanoparticles with an average size of 6.9 nm were located on the external MMT surface, mostly in its pores. Ag–MMT was used as a catalyst for reduction of 4-nitrophenol with sodium borohydride forming 4-aminophenol. After 30 s the reaction kinetics changed from zero order to first order, which was explained by means of the Langmuir–Hinshelwood model. The whole reduction was completed after 290 s. During this time min. 95 wt. % of Ag nanoparticles stayed fixed on the MMT support. - Highlights: • Ag nanoparticles with an average size of 6.9 nm were reduced on montmorillonite. • Ag nanoparticles were fixed in montmorillonite pores forming a stable nanocomposite. • Ag in the nanocomposite showed catalytic activity for reduction of 4-nitrophenol. • Reaction kinetics was explained by the Langmuir–Hinshelwood model

  13. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    Science.gov (United States)

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-09-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested.

  14. Scalable synthesis of Cu-based ultrathin nanowire networks and their electrocatalytic properties

    Science.gov (United States)

    Hong, Wei; Wang, Jin; Wang, Erkang

    2016-02-01

    In this research, we developed an easy way to generate CuM (M = Pd, Pt and PdPt) ultrathin nanowire networks by simply injecting the metallic precursors into an aqueous solution which contained sodium borohydride under vigorous stirring. The reaction can be finished quickly without needing any other reagents, thus leaving the products with a clean surface. The prepared materials show an ultrathin diameter of less than 5 nanometers. The reaction can be easily amplified, resulting in scalable products. These properties combined with the superior catalytic performance of the prepared CuM nanowire networks underpin their potential use in glycerol electrooxidation reaction.In this research, we developed an easy way to generate CuM (M = Pd, Pt and PdPt) ultrathin nanowire networks by simply injecting the metallic precursors into an aqueous solution which contained sodium borohydride under vigorous stirring. The reaction can be finished quickly without needing any other reagents, thus leaving the products with a clean surface. The prepared materials show an ultrathin diameter of less than 5 nanometers. The reaction can be easily amplified, resulting in scalable products. These properties combined with the superior catalytic performance of the prepared CuM nanowire networks underpin their potential use in glycerol electrooxidation reaction. Electronic supplementary information (ESI) available: Experimental details, additional TEM, XPS and electrochemical characterizations. See DOI: 10.1039/c5nr07516e

  15. Visual and colorimetric detection of mercury(II) ion using gold nanoparticles stabilized with a dithia-diaza ligand

    International Nuclear Information System (INIS)

    We have developed a simple method for the highly selective colorimetric detection of dissolved mercury(II) ions via direct formation of gold nanoparticles (AuNPs). The dithia-diaza ligand 2-[3-(2-amino-ethylsulfanyl)-propylsulfanyl]-ethylamine (AEPE) was used as a stabilizer to protect AuNPs from aggregation and to impart highly selective recognition of Hg(II) ion over other metal ions. A solution of Au(III) ion is directly reduced by sodium borohydride in the presence of AEPE and the detergent Triton X-100. This results in the formation of AEPE-AuNPs and a red coloration of the solution. On the other hand, in the presence of Hg(II), the solution turns blue within a few seconds after the addition of borohydride. This can be detected spectrophotometrically or even visually. The method was successfully applied to quantify Hg(II) levels in water sample, with a minimum detectable concentration as low as 35 nM. (author)

  16. Synthesis of N-(4-pyridyl[14C]carbonylamino)-1,2,[3H]3,6-tetrahydropyridine and the mono-labelled [14C]- and [3H]-analogues

    International Nuclear Information System (INIS)

    Reaction of isonicotinic [14C] acid hydrazide with the Zinke salt afforded N-(4-pyridyl [14C] carbonylimino)pyridinium yield (A) in 81% chemical yield. Sodium borohydride reduction of (A) gave N-(4-pyridyl [14C] carbonylamino)-1,2,3,6-tetrahydropyridine in 60% chemical yield with a specific activity of 6.17 mCi mM-1. Alternatively reduction of N-(4-pyridylcarbonylimino) pyridinium yield using absolute ethanol and [3H]-water as solvent yielded N-(4-pyridylcarbonylamino)-1,2,[3H]3,6-tetrahydropyridine in 52.6% chemical yield with a specific activity of 1.14 mCi mM-1. N-(4-Pyridyl[14C]carbonylamino-1,2,[3H]3,6-tetrahydropyridine was similarly prepared by sodium borohydride reduction of (A) using absolute ethanol and [3H]-water as solvent in 46% chemical yield with specific activities of 1.31 and 5.66 mCi mM-1 respectively for [3H] and [14C]. (author)

  17. A multifaceted approach to hydrogen storage.

    Science.gov (United States)

    Churchard, Andrew J; Banach, Ewa; Borgschulte, Andreas; Caputo, Riccarda; Chen, Jian-Cheng; Clary, David; Fijalkowski, Karol J; Geerlings, Hans; Genova, Radostina V; Grochala, Wojciech; Jaroń, Tomasz; Juanes-Marcos, Juan Carlos; Kasemo, Bengt; Kroes, Geert-Jan; Ljubić, Ivan; Naujoks, Nicola; Nørskov, Jens K; Olsen, Roar A; Pendolino, Flavio; Remhof, Arndt; Románszki, Loránd; Tekin, Adem; Vegge, Tejs; Zäch, Michael; Züttel, Andreas

    2011-10-14

    The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but only if a number of currently intractable problems can be overcome. Not the least of these is the problem of storage, particularly when aimed at use onboard light-vehicles. The aim of this overview is to look in depth at a number of areas linked by the recently concluded HYDROGEN research network, representing an intentionally multi-faceted selection with the goal of advancing the field on a number of fronts simultaneously. For the general reader we provide a concise outline of the main approaches to storing hydrogen before moving on to detailed reviews of recent research in the solid chemical storage of hydrogen, and so provide an entry point for the interested reader on these diverse topics. The subjects covered include: the mechanisms of Ti catalysis in alanates; the kinetics of the borohydrides and the resulting limitations; novel transition metal catalysts for use with complex hydrides; less common borohydrides; protic-hydridic stores; metal ammines and novel approaches to nano-confined metal hydrides. PMID:21887432

  18. Reversible Low Temperature Hydrogen Storage Using Ternary Borides

    Science.gov (United States)

    Li, Wen; Vajo, John; Cumberland, Robert; Liu, Ping; Hwang, Son-Jong; Kim, Chul; Bowman, Robert

    2009-03-01

    Among many materials for hydrogen storage, complex borohydride of light metals with high hydrogen capacity, have been studied extensively. However, the thermodynamic and kinetic properties of borohydrides limit their ability to cycle hydrogen reversibly at low temperature. For example, although LiBH4 is thermodynamically quite stable, the formation of LiBH4 from LiH + B requires elevated temperatures and pressures of up to 600 C and 150 bar. Here, we report ternary borides with active boron species that can be hydrogenated forming [BH4]^- anions at temperatures as low as ˜280 C. These ternary borides were prepared through milling of precursors followed by thermal treatment under inert atmosphere. Samples were then milled with additional binary hydrides before hydrogenation. Analysis using FTIR and ^11B MAS NMR indicated that the ternary borides were hydrogenated to [BH4]^- species with good kinetics. After hydrogenation, the mixture could be cycled with dehydrogenation occurring in two steps that begin at 280 C and 345 C, respectively. Characterization using FTIR, ^11B MAS NMR, and XRD, indicates that the [BH4]^- anions are consumed in the first dehydrogenation step.

  19. Comparison of palladium/zinc oxide photocatalysts prepared by different palladium doping methods for congo red degradation.

    Science.gov (United States)

    Güy, Nuray; Çakar, Soner; Özacar, Mahmut

    2016-03-15

    ZnO nanoplates were synthesized by microwave-hydrothermal methods. Pd doped ZnO photocatalysts were prepared by microwave irradiation, UV irradiation, and borohydride reduction methods. The Pd/ZnO photocatalysts were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and UV-vis spectrophotometry. The obtained FESEM results confirmed the dispersion of Pd nanoparticles on the surface of ZnO nanoplates. The optical band gap value was calculated as 3.25 eV from UV-Vis diffuse reflectance spectra of ZnO and different Pd/ZnO photocatalysts. Since the preparation method of the photocatalyst is of great importance for determining the photocatalysis, the effect of this on photocatalysis was investigated. The results of the photocatalytic degradation of congo red in aqueous solutions under the UV-light showed that Pd/ZnO prepared by borohydride reduction method exhibited higher photocatalytic activity than the other ones. A plausible mechanism for the enhanced photocatalytic activity by Pd doped ZnO was proposed. The kinetics of photodecomposition of congo red, and the identification of photoproducts were investigated by using liquid chromatography-mass spectrometry (LC-MS). The possible photodegradation pathway of congo red was also proposed according to the structures of the photoproducts obtained from LC-MS data. PMID:26720515

  20. Surface geometry of tryptophan adsorbed on gold colloidal nanoparticles

    Science.gov (United States)

    Hussain, Shafqat; Pang, Yoonsoo

    2015-09-01

    Two distinct surface-enhanced Raman (SER) spectra of tryptophan depending on the surface adsorption geometry were obtained by using colloidal gold nanoparticles reduced by borohydride and citrate ions. According to the vibrational assignments based on DFT simulations, the SER spectra of tryptamine and 3-indolepropionic acid, and the pH dependence of tryptophan SER spectrum, we found that some indole ring vibrations are very sensitive to the surface adsorption geometry of the molecules. With citrate-reduced gold colloids, tryptophan and related molecules mainly adsorb via the protonated amine group while maintaining a perpendicular geometry of the indole ring to the surface. However, a flat geometry of the indole ring to the surface is preferred on the borohydride-reduced gold colloids where the surface adsorption occurs mainly through the indole ring π electrons. By comparing our results with previous reports on the SER spectra of tryptophan on various silver and gold surfaces, we propose a general adsorption model of tryptophan on metal nanosurfaces.

  1. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  2. A simple and generic approach for synthesizing colloidal metal and metal oxide nanocrystals

    Science.gov (United States)

    Cloud, Jacqueline E.; Yoder, Tara S.; Harvey, Nathan K.; Snow, Kyle; Yang, Yongan

    2013-07-01

    A simple and generic approach--alternating voltage induced electrochemical synthesis (AVIES)--has been reported for synthesizing highly dispersed colloidal metal (Au, Pt, Sn, and Pt-Pd) and metal oxide (ZnO and TiO2) nanocrystals. The respective nanocrystals are produced when a zero-offset alternating voltage at 60 Hz is applied to a pair of identical metal wires, which are inserted in an electrolyte solution containing capping ligands. In the case of Au, the obtained nanocrystals are highly crystalline nano-icosahedra of 14 +/- 2 nm in diameter, the smallest Au icosahedra synthesized in aqueous solutions via green chemistry. Their catalytic activity has been demonstrated through facilitating the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride. This AVIES approach is an environmentally benign process and can be adopted by any research lab.

  3. Abroma augusta Linn bark extract-mediated green synthesis of gold nanoparticles and its application in catalytic reduction

    Science.gov (United States)

    Das, Subhajit; Bag, Braja Gopal; Basu, Ranadhir

    2014-11-01

    The bark extract of Abroma augusta Linn is rich in medicinally important phytochemicals including antioxidants and polyphenols. First one step green synthesis of gold nanoparticles (AuNPs) has been described utilizing the bark extract of Abroma augusta L. and chloroauric acid under very mild reaction conditions. The phytochemicals present in the bark extract acted both as a reducing as well as a stabilizing agent, and no additional stabilizing and capping agents were needed. Detailed characterizations of the stabilized AuNPs were carried out by surface plasmon resonance spectroscopy, high resolution transmission electron microscopy, and X-ray diffraction studies. The catalytic activity of the freshly synthesized gold nanoparticles has been demonstrated for the sodium borohydride reduction of 4-nitrophenol to 4-aminophenol, and the kinetics of the reduction reaction have been studied spectrophotometrically.

  4. In situ generation of silver nanoparticles within crosslinked 3D guar gum networks for catalytic reduction.

    Science.gov (United States)

    Zheng, Yian; Zhu, Yongfeng; Tian, Guangyan; Wang, Aiqin

    2015-02-01

    The direct use of guar gum (GG) as a green reducing agent for the facile production of highly stable silver nanoparticles (Ag NPs) within this biopolymer and subsequent crosslinking with borax to form crosslinked Ag@GG beads with a 3D-structured network are presented here. These crosslinked Ag@GG beads were characterized using UV-vis absorption spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy, and then tested as a solid-phase heterogenerous catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of excess borohydride. The results indicate that these crosslinked Ag@GG beads show excellent catalytic performance for the reduction of 4-NP within 20 min and can be readily used for 10 successive cycles. PMID:25445685

  5. Lantana camara Linn leaf extract mediated green synthesis of gold nanoparticles and study of its catalytic activity

    Science.gov (United States)

    Dash, Shib Shankar; Bag, Braja Gopal; Hota, Poulami

    2015-03-01

    A facile one-step green synthesis of stable gold nanoparticles (AuNPs) has been described using chloroauric acid (HAuCl4) and the leaf extract of Lantana camara Linn (Verbenaceae family) at room temperature. The leaf extract enriched in various types of plant secondary metabolites is highly efficient for the reduction of chloroaurate ions into metallic gold and stabilizes the synthesized AuNPs without any additional stabilizing or capping agents. Detailed characterizations of the synthesized gold nanoparticles were carried out by surface plasmon resonance spectroscopy, transmission electron microscopy, dynamic light scattering, Zeta potential, X-ray diffraction and Fourier transform-infrared spectroscopy studies. The synthesized AuNPs have been utilized as a catalyst for the sodium borohydride reduction of 4-nitrophenol to 4-aminophenol in water at room temperature under mild reaction condition. The kinetics of the reduction reaction has been studied spectrophotometrically.

  6. Spectroscopic Studies of the Interaction of Silver Nanoparticles with Methylene Blue

    Institute of Scientific and Technical Information of China (English)

    Chuan DONG; Jun ZHANG; Dai-zi ZHOU

    2010-01-01

    The interaction between silver nanoparticles and Methylene Blue(MB)is studied by UV-Vis spectroscopy and fluorescence spectrometry.The UN-Vis absorption of the silver nanoparticles dramatically with the addition of MB.However,no obvious changes of absorption spectra of MB are observed when silver colloids ate added into the MB solution.In the presence of surfactant SDS,the catalysis of the silver nanoparticles in the reducton of MB by sodium borohydride is exhibited by UV-Vis and fluorescence spectroscopy of MB displaying faster response compared with the absence of the silver nanoparticles.The results show that the activity of surfactant SDS modified silver nanoparticles is great and a strong physical adsorption to MB exists.

  7. Synthesis, characterization and vibrational spectroscopic studies of different particle size of gold nanoparticle capped with polyvinylpyrrolidone

    Energy Technology Data Exchange (ETDEWEB)

    Seoudi, R., E-mail: rsmawed@yahoo.co [Spectroscopy Department, Physics Division, National Research Center, Dokki, Cairo 12622 (Egypt); Fouda, A.A. [Spectroscopy Department, Physics Division, National Research Center, Dokki, Cairo 12622 (Egypt); Elmenshawy, D.A. [Physics Department, Faculty of Women, Ain Shams University, Cairo (Egypt)

    2010-02-01

    Different sizes of gold nanoparticle (AuNPs) were prepared by UV irradiation technique. Polyvinylpyrrolidone (PVP) used as a stabilizing agent, and reducing agent was sodium borohydride. The main particle size was calculated from TEM images and the particle size was depending on the wavelength and time of UV irradiation. The FTIR data obtained that the band position of C=O and C-N of pyrrolidone ring was shifted as a result of donor-acceptor interactions between these groups with AuNPs surface. The origin of the surface plasmon resonance (SPR) was explored from UV-VIS spectroscopy. The surface plasmon resonance (SPR) band position was explained in terms of the size of AuNPs. The results were confirmed that SP resonance was depending on the particle sizes that depend on the wavelength and time of UV irradiation.

  8. Synthesis of copper nanocolloids using a continuous flow based microreactor

    Science.gov (United States)

    Xu, Lei; Peng, Jinhui; Srinivasakannan, C.; Chen, Guo; Shen, Amy Q.

    2015-11-01

    The copper (Cu) nanocolloids were prepared by sodium borohydride (NaBH4) reduction of metal salt solutions in a T-shaped microreactor at room temperature. The influence of NaBH4 molar concentrations on copper particle's diameter, morphology, size distribution, and elemental compositions has been investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The ultraviolet-visible spectroscopy (UV-vis) was used to verify the chemical compounds of nanocolloids and estimate the average size of copper nanocolloids. The synthesized copper nanocolloids were uniform in size and non-oxidized. A decrease in the mean diameter of copper nanocolloids was observed with increasing NaBH4 molar concentrations. The maximum mean diameter (4.25 nm) occurred at the CuSO4/NaBH4 molar concentration ratio of 1:2.

  9. A Sensitive Surface-enhanced Raman Scattering Method for Determination of Melamine with Aptamer-modified Nanosilver Probe

    Institute of Scientific and Technical Information of China (English)

    温桂清; 周莲平; 李廷盛; 梁爱惠; 蒋治良

    2012-01-01

    The small nanosilver was prepared by the sodium borohydride procedure. The aptamer was used to modify nanosilver to obtain a nanosilver-aptamer (AgssDNA) SERS probe for the determination of melamine. In pH 6.6 phosphate buffer solution and in the presence of NaCI, the AgssDNA probe specifically combined with melamine to release nanosilver particles that were aggregated to nanosilver clusters, which exhibited SERS effect at 240 cm-1. When melamine concentration increased, the nanosilver clusters increased, and the SERS intensity at 240 cm-1 in- creased. The increased SERS intensity AI240cm, is linear to melamine concentration in the range of 6.3--403.6 μg.L 1, with a detection limit of 1.2 μg L 1. This assay was applied to determination of melamine in milk, with sat- isfactory results. Keywords melamine, apatmer-modified nanosilver, aggregation, surface-enhanced Raman scattering

  10. Green synthesis of silver and gold nanoparticles employing levan, a biopolymer from Acetobacter xylinum NCIM 2526, as a reducing agent and capping agent.

    Science.gov (United States)

    Ahmed, Khan Behlol Ayaz; Kalla, Divya; Uppuluri, Kiran Babu; Anbazhagan, Veerappan

    2014-11-01

    With a vision of finding greener materials to synthesize nanoparticles, we report the production and isolation of levan, a polysaccharide with repeating units of fructose, from Acetobacter xylinum NCIM2526. The isolated levan were characterized using potassium ferricyanide reducing power assay, Fourier transform infra-red (FTIR) spectroscopy and (1)H nuclear magnetic resonance spectroscopy ((1)H NMR). To exploit levan in nanotechnology, we present a simple and greener method to synthesize silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using biopolymer, levan as both reducing and stabilizing agents. The morphology and stability of the AgNPs and AuNPs were examined by transmission electron microscopy (TEM) and UV-vis absorption (UV-vis) spectroscopy. The possible capping mechanism of the nanoparticles was postulated using FTIR studies. As synthesized biogenic nanoparticles showed excellent catalytic activity as evidenced from sodium borohydride mediated reduction of 4-nitro phenol and methylene blue. PMID:25129779

  11. 99mTc labeling of the scorpion (Tityus serrulatus) antivenom

    International Nuclear Information System (INIS)

    F(ab')2 is the fragment involved in the immunotherapy for scorpion stings and it would be convenient to label it with 99mTc for organ distribution and pharmacokinetics studies. The aim of the present study was to label scorpion antivenom F(ab')2 with 99mTc keeping its biological activity, integrity and stability. High labeling yield was obtained using stannous chloride and sodium borohydride. Stability, immunoreactivity and integrity of 99mTc-F(ab')2 was preserved. It was not observed any difference between potencies of unlabeled and labeled antivenom. 99mTc-F(ab')2 can be a useful tool for use in biodistribution and pharmacokinetics studies on the evaluation of the efficacy of the antivenom against scorpion envenomation. (author)

  12. The effect of the nano-silica support on the catalytic reduction of water by gold, silver and platinum nanoparticles--nanocomposite reactivity.

    Science.gov (United States)

    Zidki, T; Bar-Ziv, R; Green, U; Cohen, H; Meisel, D; Meyerstein, D

    2014-08-01

    Pt°-NPs, prepared by the reduction of Pt(IV) salts with borohydride, do not catalyse the reduction of water in the presence of the strongly-reducing ˙C(CH3)2OH radicals. However, supporting the same metal nanoparticles (M°-NPs) with SiO2 alters the catalytic properties enabling the reaction. This effect depends both on the nature of M° and concentration of the composite nanoparticles. At low nanocomposite concentration: for M = Au nearly no effect is observed; for M = Ag the support decreases the catalytic reduction of water and for M = Pt the support initiates the catalytic process. At high nanocomposite concentration: for M = Au the reactivity is considerably lower and for M = Ag or Pt no catalysis is observed. Furthermore, for M = Ag or Pt H2 reduces the ˙C(CH3)2OH radicals. PMID:24947417

  13. Novel Pd-Cu/bacterial cellulose nanofibers: Preparation and excellent performance in catalytic denitrification

    Science.gov (United States)

    Sun, Dongping; Yang, Jiazhi; Li, Jun; Yu, Junwei; Xu, Xiaofeng; Yang, Xuejie

    2010-01-01

    In this work, we describe a novel facile method to prepare long one-dimensional hybrid nanofibers by using hydrated bacterial cellulose nanofibers (BCF) as template. Palladium-copper nanoparticles were prepared in BCF by immersing BCF in a mixture solution of PdCl 2 and CuCl 2 in water and followed reduction of absorbed metallic ion inside of BCF to the metallic Pd-Cu nanoparticles using potassium borohydride. The bare BCF and the composites were characterized by a range of analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results reveal that the Pd-Cu nanoparticles were homogeneously precipitated on the BCF surface. The Pd-Cu/BCF was used as a catalyst for water denitrification, which showed that it has high catalytic activity.

  14. Novel Pd-Cu/bacterial cellulose nanofibers: Preparation and excellent performance in catalytic denitrification

    Energy Technology Data Exchange (ETDEWEB)

    Sun Dongping, E-mail: dongpingsun@163.com [Key Laboratory for Soft Chemistry and Functional Materials of Ministry Education, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang Jiazhi; Li Jun; Yu Junwei; Xu Xiaofeng; Yang Xuejie [Key Laboratory for Soft Chemistry and Functional Materials of Ministry Education, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2010-01-15

    In this work, we describe a novel facile method to prepare long one-dimensional hybrid nanofibers by using hydrated bacterial cellulose nanofibers (BCF) as template. Palladium-copper nanoparticles were prepared in BCF by immersing BCF in a mixture solution of PdCl{sub 2} and CuCl{sub 2} in water and followed reduction of absorbed metallic ion inside of BCF to the metallic Pd-Cu nanoparticles using potassium borohydride. The bare BCF and the composites were characterized by a range of analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results reveal that the Pd-Cu nanoparticles were homogeneously precipitated on the BCF surface. The Pd-Cu/BCF was used as a catalyst for water denitrification, which showed that it has high catalytic activity.

  15. A novel Ag catalyzation process using swelling impregnation method for electroless Ni deposition on Kevlar® fiber

    Science.gov (United States)

    Pang, Hongwei; Bai, Ruicheng; Shao, Qinsi; Gao, Yufang; Li, Aijun; Tang, Zhiyong

    2015-12-01

    A novel Ag catalyzation process using swelling impregnation pretreatment method was developed for electroless nickel (EN) deposition on Kevlar fiber. Firstly, the fiber was immersed into an aqueous dimethylsulfoxide (DMSO) solution of silver nitrate to impart silver nitrate into the inner part of the fiber near the surface. Subsequently silver nitrate was reduced to metal silver nanoparticles on the fiber surface by treatment with aqueous solution of sodium borohydride. After electroless plating, a dense and homogeneous nickel coating was obtained on the fiber surface. The silver nanoparticles formed at the fiber surface functioned as a catalyst for electroless deposition as well as an anchor for the plated layer. The study also revealed that the incorporation of surfactant sodium dodecyl sulfate (SDS) in electroless nickel plating bath can enhance the adhesion strength of EN layer with the fiber surface and minimize the surface roughness of the EN coating. The Ni plated Kevlar fiber possessed excellent corrosion resistance and high tensile strength.

  16. Active targeting of cancer cells using folic acid-conjugated platinum nanoparticles

    Science.gov (United States)

    Teow, Yiwei; Valiyaveettil, Suresh

    2010-12-01

    Interaction of nanoparticles with human cells is an interesting topic for understanding toxicity and developing potential drug candidates. Water soluble platinum nanoparticles were synthesized viareduction of hexachloroplatinic acid using sodium borohydride in the presence of capping agents. The bioactivity of folic acid and poly(vinyl pyrrolidone) capped platinum nanoparticles (Pt-nps) has been investigated using commercially available cell lines. In the cell viability experiments, PVP-capped nanoparticles were found to be less toxic (>80% viability), whereas, folic acid-capped platinum nanoparticles showed a reduced viability down to 24% after 72 h of exposure at a concentration of 100 μg ml-1 for MCF7 breast cancer cells. Such toxicity, combined with the possibility to incorporate functional organic molecules as capping agents, can be used for developing new drug candidates.

  17. Ultrasound assisted green synthesis of poly(vinyl alcohol) capped silver nanoparticles for the study of its antifilarial efficacy

    Science.gov (United States)

    Saha, Swadhin Kr.; Chowdhury, Pranesh; Saini, Prasanta; Babu, Santi P. Sinha

    2014-01-01

    Poly(vinyl alcohol) (PVA) capped stable silver nanoparticles (AgNP) have been synthesized sonochemically with the help of catalytic amount of a biomolecule (tyrosine). An attempt has been made to reduce the harmfull chemical additives (like sodium borohydride, hydrazine, dimethyl formamide, etc.) used in conventional methods. Tyrosine shows excellent reducing activity in presence of PVA stabilizer. Ultra-sound increased the reaction rate and yield, and improved the quality of the AgNP in terms of regular size distribution. The synthetic route follows the principles of green chemistry. Bioactivity has been tested in the light of antifilarial efficacy through induction of apoptosis. The biocompatible polymer (PVA) capped AgNPs are suitable for the treatment of filarial nematode.

  18. A facile synthesis of metal nanoparticle - graphene composites for better absorption of solar radiation

    International Nuclear Information System (INIS)

    Herein, a facile chemical approach has been adopted to prepare silver nanoparticles (AgNPs)- graphene (G) composite to study photothermal effect. Sodium borohydride (SBH), a strong reducing agent has been selected for this work. Effect of SBH concentrations on optical behavior of AgNPs-G composite was also investigated. Resultant materials were characterized by various techniques including X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), optical absorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM micrographs confirm wrapping of AgNPs into graphene whereas XRD analysis reveals their particle size variation between 47 nm to 69 nm. Optical studies throw a light on their strong absorption behavior towards solar radiation

  19. 153Sm metallic-hydroxide macroaggregates. An improved preparation for radiation synovectomy

    International Nuclear Information System (INIS)

    A new type of preparation employing 153Sm metallic-hydroxide macroaggregates (153Sm-MHM) for radiation synovectomy was developed. The radiopharmaceutical was prepared by reacting the aqueous solution of 153SmCl3 with sodium borohydride solution in 0.5N NaOH. Microscopic analysis showed that 153Sm-MHM mean particle size was 4μm (range 1-15 μm) avoiding the formation of fine particles (153Sm-hydroxide macroaggregates preparations (153Sm-HM). Also, suspension properties as sedimentation rate, were better for 153Sm-MHM than for 153Sm-hydroxyapatite and 153Sm-HM. Biological studies in normal rabbits demonstrated high retention into de Knee joint space even at 48 h after administration of 153Sm-MHM (>99%). (author)

  20. Carbon supported trimetallic nickel-palladium-gold hollow nanoparticles with superior catalytic activity for methanol electrooxidation

    Science.gov (United States)

    Shang, Changshuai; Hong, Wei; Wang, Jin; Wang, Erkang

    2015-07-01

    In this paper, Ni nanoparticles (NPs) are prepared in an aqueous solution by using sodium borohydride as reducing agent. With Ni NPs as the sacrificial template, hollow NiPdAu NPs are successfully prepared via partly galvanic displacement reaction between suitable metal precursors and Ni NPs. The as-synthesized hollow NiPdAu NPs can well dispersed on the carbon substrate. Transmission electron microscopy, X-ray diffraction and inductively coupled plasma mass spectrometry are taken to analyze the morphology, structure and composition of the as-synthesized catalysts. The prepared catalysts show superior catalytic activity and stability for methanol electrooxidation in alkaline media compared with commercial Pd/C and Pt/C. Catalysts prepared in this work show great potential to be anode catalysts in direct methanol fuel cells.

  1. Experimental Study of Interfacial Friction in NaBH{sub 4} Solution in Microchannel Dehydrogenation Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seok Hyun; Hwang, Sueng Sik; Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of)

    2014-02-15

    Sodium borohydride (NaBH{sub 4}) is considered as a secure metal hydride for hydrogen storage and supply. In this study, the interfacial friction of two-phase flow in the dehydrogenation of aqueous NaBH{sub 4} solution in a microchannel with a hydraulic diameter of 461 μm is investigated for designing a dehydrogenation chemical reactor flow passage. Because hydrogen gas is generated by the hydrolysis of NaBH{sub 4} in the presence of a ruthenium catalyst, two different flow phases (aqueous NaBH{sub 4} solution and hydrogen gas) exist in the channel. For experimental studies, a microchannel was fabricated on a silicon wafer substrate, and 100-nm ruthenium catalyst was deposited on three sides of the channel surface. A bubbly flow pattern was observed. The experimental results indicate that the two-phase multiplier increases linearly with the void fraction, which depends on the initial concentration, reaction rate, and flow residence time.

  2. Theoretical Studies on Dehydrogenation Reactions in Mg2(BH4)2(NH2)2 Compounds

    Institute of Scientific and Technical Information of China (English)

    Zheng Chen; Zhe-ning Chen; An-an Wu; Guo-tao Wu; Zhi-tao Xiong; Ping Chen; Xin Xu

    2012-01-01

    Borohydrides have been recently hightlighted as prospective new materials due to their high gravimetric capacities for hydrogen storage.It is,therefore,important to understand the underlying dehydrogenation mechanisms for further development of these materials.We present a systematic theoretical investigation on the dehydrogenation mechanisms of the Mg2(BH4)2(NH2)2 compounds.We found that dehydrogenation takes place most likely via the intermolecular process,which is favorable both kinetically and thermodynamically in comparison with that of the intramolecular process.The dehydrogenation of Mg2(BH4)2(NH2)2 initially takes place via the direct combination of the hydridic H in BH4-and the protic H in NH2-,followed by the formation of Mg-H and subsequent ionic recombination of Mg-Hδ-… Hδ+-N.

  3. The chemical properties and functional role of a lysine residue within the active site of native sodium and potassium ion-activated adenosinetriphosphatase

    International Nuclear Information System (INIS)

    The peptide, HLLVMKGAPER, which contains Lysine 501 of the α polypeptide can be released from intact sodium and potassium ion activated adenosinetriphosphatase by tryptic digestion. An immunoadsorbent directed against the carboxy-terminal, -GAPER, has been constructed. Sealed, right-side-out vesicles, prepared from canine renal kidneys, were labeled with pyridoxal phosphate and sodium [3H]borohydride in the absence or presence of saponin, respectively. Large increases in the incorporation of radioactivity into the peptides bound by the immunoadsorbent were observed in the digest obtained from the vesicles exposed to saponin. From the results of several control experiments examining the labeling reaction it could be concluded that the increase in the extent of modification was due to the cytoplasmic disposition of this segment in the native enzyme

  4. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima

    2014-11-12

    Silver nanoparticles were deposited on the surface and pore walls of block copolymer membranes with highly ordered pore structure. Pyridine blocks constitute the pore surfaces, complexing silver ions and promoting a homogeneous distribution. Nanoparticles were then formed by reduction with sodium borohydride. The morphology varied with the preparation conditions (pH and silver ion concentration), as confirmed by field emission scanning and transmission electron microscopy. Silver has a strong biocide activity, which for membranes can bring the advantage of minimizing the growth of bacteria and formation of biofilm. The membranes with nanoparticles prepared under different pH values and ion concentrations were incubated with Pseudomonas aeruginosa and compared with the control. The strongest biocidal activity was achieved with membranes containing membranes prepared under pH 9. Under these conditions, the best distribution with small particle size was observed by microscopy.

  5. Two-Phase Dechlorination/Detoxification of Lindane (Hexachlorocyclohexane

    Directory of Open Access Journals (Sweden)

    Abdul Ghaffar

    2014-01-01

    Full Text Available Dechlorination of lindane was carried out in a two-phase reaction. In first phase Devarda’s alloy and sodium borohydride were used in aqueous/ethanol reaction media. The reaction duration and temperature were optimized. In first phase higher dechlorination (78% was achieved at 80°C with 40-minute reaction time and the products were chlorobenzene, dichlorobenzene, and chlorocyclohexane. In second phase, Ca(OH2 and sulfur were added in reaction media. The reactions conditions like temperature and reaction time were optimized. After 30 minutes, dechlorination was enhanced from 78% to 94% and the final products were benzene, phenol, catechol, benzenethiol, cyclohexane, cyclohexanol, and cyclohexanethiol. The results suggested that dechlorination of lindane in first and second phase was carried out through hydrodechlorination and substitution reactions, respectively. The developed method was applied for lindane containing real wastewater and higher dechlorination (91% was achieved under optimized reaction conditions.

  6. A totally phosphine-free synthesis of metal telluride nanocrystals by employing alkylamides to replace alkylphosphines for preparing highly reactive tellurium precursors.

    Science.gov (United States)

    Yao, Dong; Liu, Yi; Zhao, Wujun; Wei, Haotong; Luo, Xintao; Wu, Zhennan; Dong, Chunwei; Zhang, Hao; Yang, Bai

    2013-10-21

    Despite the developments in the wet chemical synthesis of high-quality semiconductor nanocrystals (NCs) with diverse elemental compositions, telluride NCs are still irreplaceable materials owing to their excellent photovoltaic and thermoelectric performances. Herein we demonstrate the dissolution of elemental tellurium (Te) in a series of alkylamides by sodium borohydride (NaBH4) reduction at relatively low temperature to produce highly reactive precursors for hot-injection synthesis of telluride NCs. The capability to tune the reactivity of Te precursors by selecting injection temperature permits control of NC size over a broad range. The current preparation of Te precursors is simple, economical, and totally phosphine-free, which will promote the commercial synthesis and applications of telluride NCs. PMID:24056800

  7. Microstructure and magnetic properties of MFe2O4 (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

    International Nuclear Information System (INIS)

    Three kinds of spinel ferrite nanocrystals, MFe2O4 (M = Co, Ni, and Mn), are synthesized using colloid mill and hydrothermal method. During the synthesis process, a rapid mixing and reduction of cations with sodium borohydride (NaBH4) take place in a colloid mill then through a hydrothermal reaction, a slow oxidation and structural transformation of the spinel ferrite nanocrystals occur. The phase purity and crystal lattice parameters are estimated by X-ray diffraction studies. Scanning electron microscopy and transmission electron microscopy images show the morphology and particle size of the as-synthesized ferrite nanocrystals. Raman spectrum reveals active phonon modes at room temperature, and a shifting of the modes implies cation redistribution in the tetrahedral and octahedral sites. Magnetic measurements show that all the obtained samples exhibit higher saturation magnetization (Ms). Meanwhile, experiments demonstrate that the hydrothermal reaction time has significant effects on microstructure, morphologies, and magnetic properties of the as-synthesized ferrite nanocrystals

  8. Reversible hydrogen storage materials

    Science.gov (United States)

    Ritter, James A.; Wang, Tao; Ebner, Armin D.; Holland, Charles E.

    2012-04-10

    In accordance with the present disclosure, a process for synthesis of a complex hydride material for hydrogen storage is provided. The process includes mixing a borohydride with at least one additive agent and at least one catalyst and heating the mixture at a temperature of less than about 600.degree. C. and a pressure of H.sub.2 gas to form a complex hydride material. The complex hydride material comprises MAl.sub.xB.sub.yH.sub.z, wherein M is an alkali metal or group IIA metal, Al is the element aluminum, x is any number from 0 to 1, B is the element boron, y is a number from 0 to 13, and z is a number from 4 to 57 with the additive agent and catalyst still being present. The complex hydride material is capable of cyclic dehydrogenation and rehydrogenation and has a hydrogen capacity of at least about 4 weight percent.

  9. Room-temperature synthesis and electrocatalysis of carbon nanotubes supported palladium–iron alloy nanoparticles

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) supported palladium–iron bimetallic nanoparticles (Pd–Fe/CNTs) catalyst is synthesized using palladium hexacyanoferrate (PdHCF) as reaction precursor. In this method, the negatively charged PdHCF nanoparticles self-assemble on the positively charged polydiallyldimethylammonium chloride (PDDA) functionalized CNTs through electrostatic interaction, and then are reduced to Pd–Fe alloy nanoparticles by sodium borohydride. The physicochemical properties of Pd–Fe/CNTs are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). These structural analyses reveal that the Pd–Fe/CNTs catalyst possesses the high alloying degree and the small particle size. Electrochemical measurements show that the eletrocatalytic activity of the Pd–Fe/MWCNTs catalyst for the methanol oxidation is better than that of the Pd/CNTs catalyst, which originates from the synergistic effect between Pd atom and Fe atom

  10. Fabrication And Properties Of Silver Based Multiwall Carbon Nanotube Composite Prepared By Spark Plasma Sintering Method

    Directory of Open Access Journals (Sweden)

    Lis M.

    2015-06-01

    Full Text Available The paper presents results of investigations of the obtained nanocomposite materials based on silver with addition of multiwall carbon nanotubes. The powder of carbon nanotubes content from 0.1 to 3 wt. % was produced by application of powder metallurgy methods, through mixing and high-energetic milling, and also chemical methods. Modification of carbon nanotubes included electroless deposition of silver particles on the carbon nanotube active surfaces and chemical reduction with strong reducing agent – sodium borohydride (NaBH4. The obtained powder mixtures were consolidated by SPS – Spark Plasma Sintering method. The formed composites were subjected to tests of relative density, electrical conductivity and electro-erosion properties. Detailed examinations of the structure with application of X-ray microanalysis, with consideration of carbon nanotubes distribution, were also carried out. The effect of manufacturing methods on properties of the obtained composites was observed.

  11. Facilely Tuning Porous NiCo2 O4 Nanosheets with Metal Valence-State Alteration and Abundant Oxygen Vacancies as Robust Electrocatalysts Towards Water Splitting.

    Science.gov (United States)

    Zhu, Chengzhou; Fu, Shaofang; Du, Dan; Lin, Yuehe

    2016-03-14

    Great efforts in developing clean electrochemical water splitting technology leads to the rational design and synthesis of highly efficient oxygen evolution reaction (OER) catalysts with low overpotential and fast reaction kinetics. Herein, we focus on the role that morphology and composition play in the OER performance to rationally design freestanding 3D porous NiCo2O4 nanosheets with metal valence states alteration and abundant oxygen vacancies as robust electrocatalysts towards water splitting. Besides metal valence-state alteration, surface modification regarding the evolution of oxygen vacancies is facilely realized upon the sodium borohydride treatment, which is beneficial for the enhanced OER performance. Taking advantage of the porous nanostructures and abundant surface activity sites with high reactivity, the resultant nanostructures exhibit excellent OER activity and stability in alkaline electrolytes that outperform that of pristine NiCo2O4 and commercial RuO2, thus holding great potential for the water splitting. PMID:26845062

  12. Facile synthesis of SiO{sub 2} nanoparticles for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Scano, A., E-mail: alescano80@tiscali.it; Pilloni, M., E-mail: alescano80@tiscali.it; Cabras, V., E-mail: alescano80@tiscali.it; Ennas, G. [Università di Cagliari, Dipartimento di Scienze Chimiche e Geologiche and Research Unit of the National Consortium of Materials Science and Technology (INSTM), Cittadella Universitaria di Monserrato- 09042 Monserrato (Canada) (Italy); Vazquez-Vazquez, C. [Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, Santiago de Compostela, 15782 Galicia (Spain)

    2014-10-21

    Silica nanoparticles (SiO{sub 2} NPs) for biomedical applications have been prepared by using a facile modified Stöber-synthesis. Potassium borohydride (KBH{sub 4}) has been introduced in the synthesis procedure in order to control NP size. Several samples have been prepared varying tetraethylorthosilicate (TEOS) concentration, and using different process conditions (temperature, reaction time and atmosphere). In order to study the influence of the process conditions on the NP size, morphology and properties, several characterization techniques were used. Size and morphology of the as-prepared SiO{sub 2} NPs have been studied by using Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS) techniques. Structural characterization was carried out by X-ray powder diffraction. To investigate the SiO{sub 2} NP fluorescence emission properties the fluorescence spectroscopy was also used.

  13. 碱熔、氢化物原子荧光光谱法测定土壤中微量锗%FLUORESCENCE SPECTROMETRY

    Institute of Scientific and Technical Information of China (English)

    陈锡海; 王国成

    2011-01-01

    Acidize sample that has been subjected to alkali fusion.Determine the content of germanium in phosphate medium with potassium borohydride as reducing agent,by using atomic fluorescence spectrometry.The detection limit of the method is 0.1μg/g.It was used to test 6 national level 1 soil samples and gave results consistent to recommended values.Respective test of 12 times gave RSD all below 10%.%将碱熔后的样品酸化,在磷酸介质中,以硼氢化钾为还原剂,用原子荧光光谱法测定锗的含量。该法的检出限为0.1μg/g,,测定的六个国家一级土样与推荐值相符,并且各自测定12次的RSD均小于10%。

  14. Carbon nuclear magnetic resonance spectra of oligosaccharides isolated from human milk and ovarian cyst mucin

    International Nuclear Information System (INIS)

    Natural abundance Carbon-13 nuclear magnetic resonance spectra at 20 MHz were reported for the three common human milk oligosaccharides, lacto-N-tetraose and lacto-N-fucopentaoses I and II, as well as for two related tetra- and hexasaccharide alditols isolated from the alkaline borohydride degradation products of an ovarian cyst glycoprotein. Spectral assignments made with the help of deuterium-induced shift (DIS), attached proton test (APT), and T1 data indicated some very irregular glycosylation shifts which were attributed to effects of steric crowding and non-nearest-neighbor interactions. Samples as small as 10 mumol of oligosaccharide gave acceptable 20-MHz spectra with the use of a 5-mm probe coil

  15. Lignin Sulfonation - A different Approach

    DEFF Research Database (Denmark)

    Bjørkmann, Anders

    2001-01-01

    The research on sulfite pulping has been characterized by the attempts to explain its chemistry. The. different approach presented is incited by perceptions about the (still) unsolved problem of the ultrastructural features of lignin in wood. A simple kinetic model has been chosen to describe the...... lignin and MWL dissolved (after extraction of the "immediate" lignin) at higher rates than W lignin. For MWL, the rate difference between pH 1.5 and 6 was moderate, compared to W lignin. Borohydride reduction did not affect the lignin dissolution from W, but gave a large decrease of sulfonation rate for...... MWL. Methylation had also a small rate effect for W, but again a large decrease for MWL....

  16. EFFECT OF PRETREATMENT ON PT-CO/C CATHODE CATALYSTS FOR THE OXYGEN-REDUCTION REACTION

    Energy Technology Data Exchange (ETDEWEB)

    Fox, E.; Colon-Mercado, H.

    2010-01-19

    Carbon supported Pt and Pt-Co electrocatalysts for the oxygen reduction reaction in low temperature fuel cells were prepared by the reduction of the metal salts with sodium borohydride and sodium formate. The effect of surface treatment with nitric acid on the carbon surface and Co on the surface of carbon prior to the deposition of Pt was studied. The catalysts where Pt was deposited on treated carbon the ORR reaction preceded more through the two electron pathway and favored peroxide production, while the fresh carbon catalysts proceeded more through the four electron pathway to complete the oxygen reduction reaction. NaCOOH reduced Pt/C catalysts showed higher activity that NaBH{sub 4} reduced Pt/C catalysts. It was determined that the Co addition has a higher impact on catalyst activity and active surface area when used with NaBH{sub 4} as reducing agent as compared to NaCOOH.

  17. Preparation of gold nanoparticles using Salicornia brachiata plant extract and evaluation of catalytic and antibacterial activity

    Science.gov (United States)

    Ayaz Ahmed, Khan Behlol; Subramanian, Swetha; Sivasubramanian, Aravind; Veerappan, Ganapathy; Veerappan, Anbazhagan

    2014-09-01

    The current study deals with the synthesis of gold nanoparticles (AuNPs) using Salicornia brachiata (Sb) and evaluation of their antibacterial and catalytic activity. The SbAuNPs showed purple color with a characteristic surface plasmon resonance peak at 532 nm. Scanning electron microscopy and transmission electron microscopy revealed polydispersed AuNPs with the size range from 22 to 35 nm. Energy dispersive X-ray and thin layer X-ray diffraction analysis clearly shows that SbAuNPs was pure and crystalline in nature. As prepared gold nanoparticles was used as a catalyst for the sodium borohydride reduction of 4-nitro phenol to 4-amino phenol and methylene blue to leucomethylene blue. The green synthesized nanoparticles exhibited potent antibacterial activity against the pathogenic bacteria, as evidenced by their zone of inhibition. In addition, we showed that the SbAuNPs in combination with the regular antibiotic, ofloxacin, exhibit superior antibacterial activity than the individual.

  18. Detection and determination of interfering 5-hydroxymethylfurfural in the analysis of caramel-coloured pharmaceutical syrups.

    Science.gov (United States)

    Hewala, I I; Blaih, S M; Zoweil, A M; Onsi, S M

    1993-02-01

    A comparison between different caramels described for use in the pharmaceutical industry is presented. An interfering substance, 5-hydroxymethylfurfural (5-HMF), was detected in some caramels. Conditions and proofs for the formation of 5-HMF are presented. Interference by 5-HMF during the analysis of the active drugs and the possibility of interaction with the active drugs during the shelf-life of the drug formulation are discussed. A limit test for 5-HMF in caramel was developed. The test depends on measuring the difference in absorbance between two equimolar solutions of caramel, one of which contains sodium borohydride. The test is sensitive and selective for the detection and determination of trace amounts of 5-HMF without interference from the brown products of caramel. PMID:8192718

  19. Method for synthesizing metal bis(borano) hypophosphite complexes

    Science.gov (United States)

    Cordaro, Joseph G.

    2013-06-18

    The present invention describes the synthesis of a family of metal bis(borano) hypophosphite complexes. One procedure described in detail is the syntheses of complexes beginning from phosphorus trichloride and sodium borohydride. Temperature, solvent, concentration, and atmosphere are all critical to ensure product formation. In the case of sodium bis(borano) hypophosphite, hydrogen gas was evolved upon heating at temperatures above 150.degree. C. Included in this family of materials are the salts of the alkali metals Li, Na and K, and those of the alkaline earth metals Mg and Ca. Hydrogen storage materials are possible. In particular the lithium salt, Li[PH.sub.2(BH.sub.3).sub.2], theoretically would contain nearly 12 wt % hydrogen. Analytical data for product characterization and thermal properties are given.

  20. Lignin Sulfonation - A different Approach

    DEFF Research Database (Denmark)

    Bjørkmann, Anders

    2001-01-01

    The research on sulfite pulping has been characterized by the attempts to explain its chemistry. The. different approach presented is incited by perceptions about the (still) unsolved problem of the ultrastructural features of lignin in wood. A simple kinetic model has been chosen to describe the...... reaction order of lignin as "concentration" (weight) in the dissolution kinetics, the cooking liquor being used in substantial excess. Three states of lignin were used: in wood as sawdust (W), in milled. wood (MW) and as milled wood lignin (MWL). Cooks were performed at pH 1.5, and 6. (measured at room...... temperature). The lignin was also modified chemically in two ways: alkaline borohydride reduction and diazomethane methylation. The reaction order (with the kinetics used) was found to be about 2/3, which is the value to be expected for particles of equal size reacting, at the particle surface. The cooks were...

  1. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

    Science.gov (United States)

    Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. PMID:24433897

  2. Nonenzymatic sensing of glucose at neutral pH values and low working potential using a glassy carbon electrode modified with platinum-iron alloy nanoparticles on a carbon support

    International Nuclear Information System (INIS)

    Alloy nanoparticles of the type PtxFe (where x is 1, 2 or 3) were synthesized by coreduction with sodium borohydride in the presence of carbon acting as a chemical support. The resulting nanocomposites were characterized by scanning electron microscopy and X-ray diffraction. The nanocomposite was placed on a glassy carbon electrode, and electrochemical measurements indicated an excellent catalytic activity for the oxidation of glucose even a near-neutral pH values and at a working voltage as low as 50 mV (vs. SCE). Under optimized conditions, the sensor responds to glucose in the 10.0 μM to 18.9 mM concentration range and with a 3.0 μM detection limit (at an S/N ratio of 3). Interferences by ascorbic acid, uric acid, fructose, acetamidophenol and chloride ions are negligible. (author)

  3. Chemical synthesis of superconducting MgB2 nanopowder

    International Nuclear Information System (INIS)

    Highlights: • MgB2 nanopowder has been synthesized by chemical method. • Powder characterized by XRD and SEM. • Superconducting behavior confirmed by susceptibility and magnetization measurements. • Nanopowder will facilitate the fabrication of small diameter MgB2 filaments. - Abstract: Superconducting MgB2 nanopowder has been synthesized through chemical reaction between lithium borohydride and magnesium hydride at relatively low temperatures. From quantitative Rietveld analysis, the average crystallite size of MgB2 powder was evaluated to be 33 nm. The superconducting transition temperature of the MgB2 nanopowder was found to be 38.8-38.9 K from magnetization and DC susceptibility measurements. Powder morphology has been evaluated by scanning electron microscopy

  4. Automated analysis of alditols by anion-exchange chromatography with photometric and fluorimetric postcolumn derivatization.

    Science.gov (United States)

    Honda, S; Takahashi, M; Shimada, S; Kakehi, K; Ganno, S

    1983-02-01

    Eight alditols were separated in ca. 80 min as their borate complexes by stepwise elution with three borate buffers on a column packed with Hitachi 2633 resin. The alditols in the eluate were derivatized automatically to colored, fluorescent products by applying sequential reactions of periodate oxidation and Hantzsch condensation, and the products were detected either photometrically or fluorimetrically. This automated method allowed simultaneous determination of 20-500 and 20-200 nmol amounts of alditols by photometric and fluorimetric monitorings, respectively. The lower limits of detection were ca. 2 and 0.5 nmol, respectively. The interference by aldoses was slight. Aldoses may be also determined as alditols by direct injection of aqueous solutions to which excess amounts of sodium borohydride have been added. This method was applied with success to urinary alditol assay and to molecular weight determination by end group analysis. PMID:6846817

  5. Synthesis and characterization of stable aqueous dispersions of graphene

    Indian Academy of Sciences (India)

    Ujjal Kumar Sur; Abhijit Saha; Aparna Datta; Balaprasad Ankamwar; Farah Surti; Sannak Dutta Roy; Debasish Roy

    2016-02-01

    A stable aqueous dispersion (5 mg ml$^{−1}$) of graphene was synthesized by a simple protocol based on three-step reduction of graphene oxide (GO) dispersion synthesized using the modified version of Hummers and Offeman method. Reduction of GO was carried out using sodium borohydride, hydrazine hydrate and dimethyl hydrazine as reducing agents. The chemically synthesized graphene was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible absorption spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopy, thermogravimetric analysis (TGA), optical microscopy. The stability of aqueous dispersions of graphene was confirmed through zeta potential measurements and the negative zeta potentials of 55–60 mV were obtained indicating the high stability of aqueous graphene dispersions.

  6. The Chemistry of Paper Preservation: Part 2. The Yellowing of Paper and Conservation Bleaching

    Science.gov (United States)

    Carter, Henry A.

    1996-11-01

    The discoloration of paper on aging is of interest to the archival community and also to the pulp and paper industry where new and improved mechanical pulps are being developed. The yellowing of paper on aging can be attributed to the presence of chromophores found in some of the products formed from the degradation of one or more components of paper. This study identifies the nature of the chromophores found in cellulose, hemicellulose and lignin. The photooxidation of lignin-containing papers and the mechanism for photoyellowing are discussed. This is followed by a description of the basic principles of conservation bleaching which involves chemically treating papers in order to remove unwanted discoloration or stains. The washing of paper and the use of oxidizing and reducing bleaches are presented. The discussion on oxidizing bleaches includes hydrogen peroxide, alkaline hypochlorite, chlorine dioxide and sunlight. The chemistry of reducing bleaches focuses on dithionites and borohydrides.

  7. Luminescent properties of terbium complexes with catecholamines and their application in analysis

    International Nuclear Information System (INIS)

    Tb complexing with a representative of catecholamines - adrenaline - is studied using the luminescence method. It is found, that the complexing takes place in alkaline medium (pH 12.0). To prevent from compound oxidation with air oxygen and to create the necessary pH in solution sodium borohydride is used. The highest luminescence intensity is achieved when the reaction occurs in aqueous-isopropanol solutions. It is established that in the complexes formed the ratio of components is the following: Tb:adrenaline=1:3. Luminescent properties of Tb complex with adrenaline are used to determine the latter. The least detectable amount of adrenaline constitutes 0.02 μg, the determination error does not exceed 5.5%

  8. Pd-PEG-PU polymer networks: A convenient catalyst for hydrogenation and Suzuki coupling reactions

    International Nuclear Information System (INIS)

    Polyethyleneglycol-polyurethane (PEG-PU) polymer network films with sodium tetrachloropalladate were fabricated by solution casting technique. The incorporated palladium ions were reduced using sodium borohydride to obtain zero-valent (metallic) palladium in the films. These films were characterized by X-ray diffraction, Fourier transform-infra red spectroscopy, atomic absorption spectroscopy and X-ray photoelectron spectroscopy for their structure and chemical composition. The films containing palladium metal are found to be highly efficient toward hydrogenation of a number of unsaturated organic compounds and Suzuki coupling reactions of haloarenes. The novelty of this catalyst system is the incorporation of palladium in the polymer network that renders the catalyst system's reusability because there is no leaching of the metal from the polymer matrix and as the catalyst system is in the form of a compact film it can be easily separated from the reaction mixture and can be reused.

  9. Thermally Activated Palm Kernel Based Carbon as a Support for Edible Oil Hydrogenation Catalyst

    Directory of Open Access Journals (Sweden)

    Abdulmajid Alshaibani

    2013-01-01

    Full Text Available Activated carbon has distinctive properties as a support for hydrogenation catalysts. Thermally activated carbon has been prepared from palm kernel shell at 1073 K and placed under nitrogen flow for 2 h. It was impregnated by palladium using toluene solution of Pd (acac2. The Pd/C was reduced using a water solution of potassium borohydride (KBH4. The Pd-B/C was characterized by the Brunauer-Emmett-Teller surface area analysis (BET, scanning electron microscopy (SEM, transmission electron microscopy (TEM and inductively-coupled plasma mass spectrometry (ICP-MS. Pd-B/C was applied for sunflower oil hydrogenation at a temperature of 373 K, hydrogen pressure of 413.5 kPa and agitation of 1400 rpm for 1 h. Pd-B/C noticeably exhibited a higher overall catalyst activity in comparison to some recently published palladium catalysts.

  10. 龙脑烯基环己醇型檀香化合物的合成研究%Study on the synthesis of campholenyl cyclohexanol type sandalwood compounds

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Campholenyl cyclohexanol type compounds, having precious sandalwoods-like aroma,were prepared from camphorenal,piperidine,MVK,PTSH catalyst,etc. via intermediate of enamine,additive reaction of Michael, cyclization in the molecule,and reduction by sodium borohydride, The reaction conditions and mechanisms were discussed,the product structures and odor were identified also.%由龙脑烯醛、哌啶、甲基乙烯基酮、PTSH催化剂等原料,经烯胺中间体、Michael加成、分子内环化、硼氢化钠还原等反应,合成出了具有珍贵檀香香气的龙脑烯基环已醇型化合物。对合成条件及反应历程作了探讨,对产物的结构及香气怍了鉴定。

  11. The synthesis of iron-nickel alloy nanoparticles using a reverse micelle technique

    International Nuclear Information System (INIS)

    Nanosized Fe0.2Ni0.8 particles were prepared by reducing their salts with sodium borohydride (NaBH4) in cationic water-in-oil (w/o) microemulsions of water/cetyl-trimethyl-amonium bromide (CTAB) and n-butanol/isooctane at 25 oC. According to the TEM and X-ray diffraction analyses, the synthesized particles were around 4-12 nm in size. Due to their nanodimensions, the particles had a primitive cubic (pc) structure rather than the body-centered cubic (BCC) structure of the bulk material. An examination of the synthesis from the reverse micelle reveals that the morphology of the iron-nickel alloy nanoparticles depends mainly on the microemulsion's composition. The magnetization of the nanoparticles was much lower than that of the bulk material, reflecting the influence of the nanodimensions on the particles' magnetizations

  12. Carbon Nanotubes Supported Pt-Ru-Ni as Methanol Electro-Oxidation Catalyst for Direct Methanol Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    Fei Ye; Shengzhou Chen; Xinfa Dong; Weiming Lin

    2007-01-01

    Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure.The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.

  13. Carbon nanofiber supported bimetallic PdAu nanoparticles for formic acid electrooxidation

    Science.gov (United States)

    Qin, Yuan-Hang; Jiang, Yue; Niu, Dong-Fang; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

    2012-10-01

    Carbon nanofiber (CNF) supported PdAu nanoparticles are synthesized with sodium citrate as the stabilizing agent and sodium borohydride as the reducing agent. High resolution transmission electron microscopy (HRTEM) characterization indicates that the synthesized PdAu particles are well dispersed on the CNF surface and X-ray diffraction (XRD) characterization indicates that the alloying degree of the synthesized PdAu nanoparticles can be improved by adding tetrahydrofuran to the synthesis solution. The results of electrochemical characterization indicate that the addition of Au can promote the electrocatalytic activity of Pd/C catalyst for formic acid oxidation and the CNF supported high-alloying PdAu catalyst possesses better electrocatalytic activity and stability for formic acid oxidation than either the CNF supported low-alloying PdAu catalyst or the CNF supported Pd catalyst.

  14. Preparation of β-Artemether%β-蒿甲醚的制备

    Institute of Scientific and Technical Information of China (English)

    罗春; 黄建军; 杨柳; 谢小灵; 柳楚英

    2012-01-01

    β-Artemether was synthesized from artemisinin by reduction with potassium borohydride to give dihydroartemisinin, which was subjected to etherification with methanol in the presence of aluminum perchlorate nonahydrate followed by recrystallization with 50% methanol in 69% overall yield and 98.5% purity.%青蒿素经硼氢化钾还原制得双氢青蒿素,再在高氯酸铝作用下与甲醇成醚,用50%甲醇重结晶后可得到高纯度的β-蒿甲醚(1),总收率约69%,纯度可达98.5%.

  15. Study of Leishmania major-infected macrophages by use of lipophosphoglycan-specific monoclonal antibodies.

    Science.gov (United States)

    Handman, E

    1990-07-01

    Leishmania major infection of macrophages is followed by a time-dependent appearance of lipophosphoglycan (LPG) that can be detected on the surface of infected cells by monoclonal antibodies. The origin of these LPG epitopes is probably the intracellular amastigote. LPG epitopes could be detected on the amastigote and the infected macrophage by a number of monoclonal antibodies directed to several distinct determinants on the phosphoglycan moiety. The macrophage-expressed LPG may be modified because, unlike the parasite LPG as expressed on promastigotes or amastigotes, it could not be radiolabeled by galactose oxidase or periodate treatment of infected cells followed by reduction with 3H-labeled sodium borohydride. Some LPG epitopes displayed on the macrophage may be anchored with glycosylphosphatidylinositol, and some may be in the water-soluble phosphoglycan form bound to macrophage integrins involved in its specific recognition. The water-soluble population could be released from the infected macrophage by gentle protease treatment. PMID:1694823

  16. Theoretical and Experimental Study of LiBH4-LiCl Solid Solution

    Directory of Open Access Journals (Sweden)

    Torben R. Jensen

    2012-03-01

    Full Text Available Anion substitution is at present one of the pathways to destabilize metal borohydrides for solid state hydrogen storage. In this work, a solid solution of LiBH4 and LiCl is studied by density functional theory (DFT calculations, thermodynamic modeling, X-ray diffraction, and infrared spectroscopy. It is shown that Cl substitution has minor effects on thermodynamic stability of either the orthorhombic or the hexagonal phase of LiBH4. The transformation into the orthorhombic phase in LiBH4 shortly after annealing with LiCl is for the first time followed by infrared measurements. Our findings are in a good agreement with an experimental study of the LiBH4-LiCl solid solution structure and dynamics. This demonstrates the validity of the adopted combined theoretical (DFT calculations and experimental (vibrational spectroscopy approach, to investigate the solid solution formation of complex hydrides.

  17. Hydrogen storage in complex metal hydrides

    Directory of Open Access Journals (Sweden)

    BORISLAV BOGDANOVIĆ

    2009-02-01

    Full Text Available Complex metal hydrides such as sodium aluminohydride (NaAlH4 and sodium borohydride (NaBH4 are solid-state hydrogen-storage materials with high hydrogen capacities. They can be used in combination with fuel cells as a hydrogen source thus enabling longer operation times compared with classical metal hydrides. The most important point for a wide application of these materials is the reversibility under moderate technical conditions. At present, only NaAlH4 has favourable thermodynamic properties and can be employed as a thermally reversible means of hydrogen storage. By contrast, NaBH4 is a typical non- -reversible complex metal hydride; it reacts with water to produce hydrogen.

  18. An easy and effective method for radiolabelling of solid lipid nanoparticles

    International Nuclear Information System (INIS)

    Nanoparticle biodistribution study is of great importance in bringing nanomedicine to patients. In this article, solid lipid nanoparticle (SLN) with dimension less than 100 nm was successfully radiolabelled with 99mTc by using sodium borohydride as a reducing agent (instead of stannous salts). Paclitaxel (PTX) was used as a model anticancer drug for the preparation of drug loaded SLN (PSLN). PSLN was characterized by standard methods. Encapsulation efficiency for PTX in PSLN was estimated by HPLC. PTX (Taxol formulation) and PSLN were radiolabelled separately and subsequent characterizations of these complexes were performed. Greater than 95 % radiolabelling efficiency was achieved and the labelling efficiency was calculated to be more than 90 % up to 24 h. Both the above-mentioned complexes passed the in vitro stability tests. PSLN achieved more brain concentration than Taxol as determined by biodistribution studies. This type of radiolabelling technique can be useful in preclinical evaluation of drug loaded SLN. (author)

  19. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate

    Directory of Open Access Journals (Sweden)

    Anandakumari Chandrasekharan Sunil Sekhar

    2016-05-01

    Full Text Available Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 103 for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to –NO2 group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

  20. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate.

    Science.gov (United States)

    Sunil Sekhar, Anandakumari Chandrasekharan; Vinod, Chathakudath Prabhakaran

    2016-01-01

    Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 10³ for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to -NO₂ group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies. PMID:27213321

  1. Camphor-mediated synthesis of carbon nanoparticles, graphitic shell encapsulated carbon nanocubes and carbon dots for bioimaging

    Science.gov (United States)

    Oza, Goldie; Ravichandran, M.; Merupo, Victor-Ishrayelu; Shinde, Sachin; Mewada, Ashmi; Ramirez, Jose Tapia; Velumani, S.; Sharon, Madhuri; Sharon, Maheshwar

    2016-02-01

    A green method for an efficient synthesis of water-soluble carbon nanoparticles (CNPs), graphitic shell encapsulated carbon nanocubes (CNCs), Carbon dots (CDs) using Camphor (Cinnamomum camphora) is demonstrated. Here, we describe a competent molecular fusion and fission route for step-wise synthesis of CDs. Camphor on acidification and carbonization forms CNPs, which on alkaline hydrolysis form CNCs that are encapsulated by thick graphitic layers and on further reduction by sodium borohydride yielded CDs. Though excitation wavelength dependent photoluminescence is observed in all the three carbon nanostructures, CDs possess enhanced photoluminescent properties due to more defective carbonaceous structures. The surface hydroxyl and carboxyl functional groups make them water soluble in nature. They possess excellent photostability, higher quantum yield, increased absorption, decreased cytotoxicity and hence can be utilized as a proficient bio imaging agent.

  2. Preparation of nickel nanoparticles in emulsion

    Institute of Scientific and Technical Information of China (English)

    ZHANG You-xian; FU Wen-jie; AN Xue-qin

    2008-01-01

    The nickel nanoparticles with different sizes and spherical shape were prepared by the reduction of nickel sulfate with sodium borohydride in the water-in-oil emulsions of water/SDBS(sodium dodecylbenzene sulfonate)/n-pentanol/n-heptane. The effects of aging time, molar ratio of water to SDBS(R) and the concentration of nickel sulfate on the size of particles were studied. The samples were characterized by transmission electron microscopy(TEM) and inductively coupled plasma spectrometry(ICP). The results show that the average particle size changes from 20 to 40 nm by adjusting aging time (15-30 min) and R (9-11.5). The concentration of nickel sulfate of 1.0 mol/L is the favorite condition.

  3. Development of 3-methoxy-4-benzyloxybenzyl alcohol (MBBA) resin as polymer-supported synthesis support: Preparation and benzyl ether cleavage by DDQ oxidation

    Indian Academy of Sciences (India)

    Qiang Huang; Bao-Zhong Zheng; Quan Long

    2010-03-01

    3-Methoxy-4-benzyloxybenzyl alcohol (MBBA) resin was synthesized by a two-step sequence under microwave irradiation involving the reaction of commercially available Merrifield resin with vanillin, followed by reduction with sodium borohydride. MBBA resin was treated with bromides in the presence of sodium hydride to afford the corresponding resin-bound benzyl ethers. Cleavage of the resin-bound benzyl ethers from the MBBA resin was carried out using 2,3-dichloro-5,6-dicyanobenzoqunone (DDQ) to give the corresponding alcohols in good yields. Moreover, the recovery, regeneration, and reuse of this polymer support could be achieved easily. MBBA resin can be developed as a kind of solid-phase synthesis bead of alcohols.

  4. Novel Pd-Cu/bacterial cellulose nanofibers: Preparation and excellent performance in catalytic denitrification

    International Nuclear Information System (INIS)

    In this work, we describe a novel facile method to prepare long one-dimensional hybrid nanofibers by using hydrated bacterial cellulose nanofibers (BCF) as template. Palladium-copper nanoparticles were prepared in BCF by immersing BCF in a mixture solution of PdCl2 and CuCl2 in water and followed reduction of absorbed metallic ion inside of BCF to the metallic Pd-Cu nanoparticles using potassium borohydride. The bare BCF and the composites were characterized by a range of analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results reveal that the Pd-Cu nanoparticles were homogeneously precipitated on the BCF surface. The Pd-Cu/BCF was used as a catalyst for water denitrification, which showed that it has high catalytic activity.

  5. Synthesis of camptothecin-loaded gold nanomaterials

    International Nuclear Information System (INIS)

    Camptothecin-loaded gold nanomaterials have been synthesized by the sodium borohydride reduction method under a strong basic condition. The obtained gold nanomaterials have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV-vis absorption spectroscopy. The camptothecin-loaded gold colloidal solution was very stable and can be stored for more than two months at room temperature without obvious changes. The color of the colloidal solution can change from wine red to purple and blue during the acidifying process. It was revealed that the release of camptothecin and the aggregation of gold nanoparticles can be controlled by tuning the solution pH. The present study implied that the gold nanomaterials can be used as the potential carrier for CPT delivery.

  6. Polyethersulfone hollow fiber modified with poly(styrenesulfonate) and Pd nanoparticles for catalytic reaction

    Science.gov (United States)

    Emin, C.; Gu, Y.; Remigy, J.-C.; Lahitte, J.-F.

    2015-07-01

    The aim of this work is the synthesis of polymer-stabilized Pd nanoparticles (PdNP) inside a functionalized polymeric porous membrane in order to develop hybrid catalytic membrane reactors and to test them in model metal-catalyzed organic reactions. For this goal, a polymeric membrane support (Polyethersulfone hollow fiber-shaped) was firstly functionalized with an ionogenic polymer (i.e. poly(styrenesulfonate) capable to retain PdNP precursors using an UV photo-grafting method. PdNP were then generated inside the polymeric matrix by chemical reduction of precursor salts (intermatrix synthesis). The catalytic performance of the PdNP catalytic membranes was evaluated using reduction of nitrophenol by sodium borohydride (NaBH4) in water.

  7. Synthesis of nanocrystalline copper oxide with dandelion-like morphology by homogeneous precipitation method

    Science.gov (United States)

    Sharma, Ravi Kant; Ghose, Ranjana

    2014-11-01

    Nanocrystalline copper oxide with dandelion-like morphology has been successfully synthesized by a simple homogeneous precipitation method using copper acetate and ammonia solution. It was obtained at low temperature (∼80 °C) in short precipitation time. The formation of dandelion-like microspheres and their size depend on calcination temperature. The synthesized samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS), surface area measurements, field emission scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray analysis. The nanocrystalline copper oxide has been explored as a good catalyst for reduction of 4-nitrophenol with sodium borohydride.

  8. Synthesis of bicyclic alkaloids from the iridoid antirrhinoside

    DEFF Research Database (Denmark)

    Frederiksen, Signe Maria

    The present thesis describes the isolation of the iridoid glucoside antirrhinoside from Antirrhinum majus, and the approaches made towards its transformation into analogues of biologically active compounds, with special interest in syntheses of bicyclic alkaloids.A synthetic piperidine monoterpene...... alkaloids. The corresponding ditosyl derivative was treated with benzylamine to afford a bicyclic N-benzylated pyrrolidine. An alternative starting material was prepared from 5,6:4',6'-di-O-isopropylidene antirrhinoside by reduction with lithium aluminum hydride. Subsequent ozonolysis and sodium borohydride...... gave the expected triol. The corresponding ditosyl derivative was treated with benzylamine or 2-methoxy-benzylamine to afford bicyclic pyrrolidines in 54-66% yield. The isopropylidene protection was removed and the unprotected pyrrolidine was acylated with benzoyl chloride to afford a potential...

  9. Facile synthesis of cysteine and triethanolamine capped CdTe nanoparticles.

    Science.gov (United States)

    Mntungwa, Nhlakanipho; Pullabhotla, Viswanadha Srirama Rajasekhar; Revaprasadu, Neerish

    2013-01-01

    Cysteine and triethanolamine capped CdTe nanoparticles have been synthesized using a simple aqueous solution based method. This method involves the reaction of tellurium powder with sodium borohydride (NaBH(4)) in water to produce telluride ions (Te(2-)), followed by the simultaneous addition of an aqueous solution of cadmium chloride or other cadmium source (acetate, carbonate and nitrate) and solution of L-cysteine ethyl ester hydrochloride or triethanolamine. The effect of capping agent on the size, structure and morphology of the as-synthesized nanoparticles was investigated. The particles were characterized using optical spectroscopy, transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. PMID:23010054

  10. Self-assembled gold nanoparticles on functionalized gold(111) studied by scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    PENG, Zhang-Quan; WANG, Er-Kang

    2000-01-01

    Nanogold colloidal solutions are prepared by the reduction of HAuClO4 with sodium citrate and sodium borohydride. 4- Aminothiophenol (ATP) self-assembled monolayers (SAMs) are formed on gold(111) surface, on which gold nanoparticles are immobilized and a sub-monolayer of the particles appears. This sub-monolayer of gold nanoparticles is characterized with scanning tunneling microscopy (STM), and a dual energy barrier tunneling model is proposed to explain the imgeability of the gold nanoparticles by STM. This model can also be used to construct multiple energy barrier structure on solid/ liquid interface and to evaluate the electron transport ability of some organic monolayers with the aid of electrochemical method.

  11. Two-dimensional self-organi-zation of 1-nonanethiol-capped gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A two-dimensional (2D) ordered hexagonal close-packed structure, formed by 1-nonanethiol-capped gold nanoparticles, is reported. The structure was constructed only by dipping the gold nanoparticle colloidal solution on flat substrate. The gold nanoparticles were synthesized as follows: First, AuCl4-1 was transferred from aqueous solution to toluene by the phase-transfer reagent of tetraoctylammo-nium bromide. Then it was reduced with aqueous sodium borohydride in the presence of a given amount of 1-nonanethiol molecules which was used to control the nuclea-tion and growth of the gold nanoparticles for the desired size. The experimental techniques, such as UV-Vis, FT-IR, and X-ray photoelectron spectroscopy (XPS), were employed to characterize the obtained product. Transmission electron microscopy (TEM) measurement demonstrated the size of the gold nanoparticle and the formation of two-dimensional ordered hexagonal close-packed gold nanoparticle structure.

  12. Thermoregulated Coacervation, Metal-Encapsulation and Nanoparticle Synthesis in Novel Triazine Dendrimers.

    Science.gov (United States)

    Ramírez-Crescencio, Fermín; Enciso, Alan E; Hasan, Mirza; da Costa, Viviana C P; Annunziata, Onofrio; Redón, Rocío; Coffer, Jeffery L; Simanek, Eric E

    2016-01-01

    The synthesis and solubility behaviors of four generation five (G5) triazine dendrimers are studied. While the underivatized cationic dendrimer is soluble in water, the acetylated and propanoylated derivatives undergo coacervation in water upon increasing temperature. Occurring around room temperature, this behavior is related to a liquid-liquid phase transition with a lower critical solution temperature (LCST) and is explained by differences in composition, notably, the hydrophobic nature of the terminal groups. Interestingly, the water solubility of the acetylated dendrimer is affected by the addition of selected metal ions. Titrating solutions of acetylated dendrimer at temperatures below the LCST with gold or palladium ions promoted precipitation, but platinum, iridium, and copper did not. Gold nanoparticles having diameters of 2.5 ± 0.8 nm can be obtained from solutions of the acetylated dendrimer at concentrations of gold less than that required to induce precipitation by treating the solution with sodium borohydride. PMID:27187331

  13. Thermoregulated Coacervation, Metal-Encapsulation and Nanoparticle Synthesis in Novel Triazine Dendrimers

    Directory of Open Access Journals (Sweden)

    Fermín Ramírez-Crescencio

    2016-05-01

    Full Text Available The synthesis and solubility behaviors of four generation five (G5 triazine dendrimers are studied. While the underivatized cationic dendrimer is soluble in water, the acetylated and propanoylated derivatives undergo coacervation in water upon increasing temperature. Occurring around room temperature, this behavior is related to a liquid-liquid phase transition with a lower critical solution temperature (LCST and is explained by differences in composition, notably, the hydrophobic nature of the terminal groups. Interestingly, the water solubility of the acetylated dendrimer is affected by the addition of selected metal ions. Titrating solutions of acetylated dendrimer at temperatures below the LCST with gold or palladium ions promoted precipitation, but platinum, iridium, and copper did not. Gold nanoparticles having diameters of 2.5 ± 0.8 nm can be obtained from solutions of the acetylated dendrimer at concentrations of gold less than that required to induce precipitation by treating the solution with sodium borohydride.

  14. TiO2/WO3/Au/MWCNT composite materials for photocatalytic hydrogen production: Advantages and draw-backs

    International Nuclear Information System (INIS)

    TiO2/WO3/Au/MWCNT composite materials were obtained using different commercial titanias (Aldrich Anatase, Aldrich Rutile, and Evonik Aeroxide P25) and Aldrich WO3. The gold nanoparticles were deposited on the semiconductor oxides' surface by chemical reduction using sodium borohydride, and the MWCNT's were combined with the composite (in different concentrations 0.1-10 wt%) by applying an ultrasonication method. The obtained nanocomposites were successfully characterized by means of X-ray diffraction, transmission electron microscopy, etc. The aim of the present work was to find the optimal composition (i.e. carbon nanotube content) of the composite for photocatalytic hydrogen production using oxalic acid as a sacrificial agent. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Investigation of catalytic activity towards oxygen reduction reaction of Pt dispersed on boron doped graphene in acid medium.

    Science.gov (United States)

    Pullamsetty, Ashok; Sundara, Ramaprabhu

    2016-10-01

    Boron doped graphene was prepared by a facile method and platinum (Pt) decoration over boron doped graphene was done in various chemical reduction methods such as sodium borohydride (NaBH4), polyol and modified polyol. X-ray diffraction analysis indicates that the synthesized catalyst particles are present in a nanocrystalline structure and transmission and scanning electron microscopy were employed to investigate the morphology and particle distribution. The electrochemical properties were investigated with the help of the rotating disk electrode (RDE) technique and cyclic voltammetry. The results show that the oxygen reduction reaction (ORR) takes place by a four-electron process. The kinetics of the ORR was evaluated using K-L and Tafel plots. The electrocatalyst obtained in modified polyol reduction method has shown the better catalytic activity compared to other two electrocatalysts. PMID:27393888

  16. Physical and chemical study of the influence of oxidation on the structure of carbon black

    International Nuclear Information System (INIS)

    This research thesis reports the study of the influence of an oxidising attack on carbon black particles by using chemical, physical and electrochemical methods to highlight the oxidation process. The carbon black particle is a spherical set essentially made of amorphous and crystalline carbon. It appears that the oxidising attack mainly occurs against the amorphous parts which surround the crystallites. If the attack is strong enough, crystallites are freed and the particle collapses. This process has been observed by using electronic microscopy, X rays, the BET nitrogen absorption method, and infra-reds. Chemical analysis revealed the presence of carboxyl, hydroxyl and quinone functional groups on the oxidised particle surface. These groups have been dosed by different methods (methylation, calcium acetate dosing, polarography and potassium borohydride reduction)

  17. The chemical properties and functional role of a lysine residue within the active site of native sodium and potassium ion-activated adenosinetriphosphatase

    Energy Technology Data Exchange (ETDEWEB)

    Xu, K.Y.

    1988-01-01

    The peptide, HLLVMKGAPER, which contains Lysine 501 of the {alpha} polypeptide can be released from intact sodium and potassium ion activated adenosinetriphosphatase by tryptic digestion. An immunoadsorbent directed against the carboxy-terminal, -GAPER, has been constructed. Sealed, right-side-out vesicles, prepared from canine renal kidneys, were labeled with pyridoxal phosphate and sodium ({sup 3}H)borohydride in the absence or presence of saponin, respectively. Large increases in the incorporation of radioactivity into the peptides bound by the immunoadsorbent were observed in the digest obtained from the vesicles exposed to saponin. From the results of several control experiments examining the labeling reaction it could be concluded that the increase in the extent of modification was due to the cytoplasmic disposition of this segment in the native enzyme.

  18. A NEW POLYMER-BOUND 1,2-DIOL AS A PROTECTING AGENT FOR SYMMETRICAL DIALDEHYDE

    Institute of Scientific and Technical Information of China (English)

    REN Qisheng; HUANG Wenqiang; ZHAO Fengzhi; Ho Binglin

    1989-01-01

    A novel polymer- bound 1,2 - diol, 3 - polystyrylsulfonyl- 1,2 - propanediol (6) had ben prepared by the reaction of sodium polystyrylsulfinate with allyl bromide, followed by oxidation and. hydrolysis or directly with 3 - chloro - 1,2 - propanediol in the presence of a phase transfer catalyst ,n - tetrabutylammonium iodide. The capacity of resin 6 for terephthaldehyde reached 1.43 mmol/g. The aldehydic groups attached to polymer 6 reacted with hydroxylamine hydrochloride or reduced by sodium borohydride giving p-formylbenzaldoxime (yield:89%)and p-formyl -benzalcohol (yield:73 A % ), respectively. The high yields of these polymer-supported reactions showed that the polymer 6 possessed the effective isolation of its reactive sites.

  19. Collagen cross-linking of skin in patients with amyotrophic lateral sclerosis

    Science.gov (United States)

    Ono, S.; Yamauchi, M.

    1992-01-01

    Collagen cross-links of skin tissue (left upper arm) from 11 patients with amyotrophic lateral sclerosis (ALS) and 9 age-matched control subjects were quantified. It was found that patients with ALS had a significant reduction in the content of an age-related, stable cross-link, histidinohydroxylysinonorleucine, that was negatively correlated with the duration of illness. The contents of sodium borohydride-reducible labile cross-links, dehydro-hydroxylysinonorleucine and dehydro-histidinohydroxymerodesmosine, were significantly increased and were positively associated with the duration of illness (r = 0.703, p less than 0.05 and r = 0.684, p less than 0.05, respectively). The results clearly indicate that during the course of ALS, the cross-linking pathway of skin collagen runs counter to its normal aging, resulting in a "rejuvenation" phenomenon of skin collagen. Thus, cross-linking of skin collagen is affected in ALS.

  20. Synthesis, characterization, biodistribution and scintigraphy of 99mTc-paclitaxel. A potential tracer of paclitaxel

    International Nuclear Information System (INIS)

    99mTc-paclitaxel was synthesized by using sodium borohydride as a reducing agent. Greater than 95 % labelling efficiency was achieved. Radiochemical purity of the synthesized 99mTc-paclitaxel was validated by thin layer chromatography (TLC) scanner and high performance liquid chromatography (HPLC). 99mTc-paclitaxel passed in vitro stability tests. Biodistribution and scintigraphy studies were performed in Sprague-Dawley rats. The biodistribution study results of 99mTc-paclitaxel were related mainly to the metabolism and excretion routes followed by the parental drug, paclitaxel. Apart from that, biodistribution of 99mTc-paclitaxel was altered after pre-treatment with cold paclitaxel. Hence, 99mTc-paclitaxel may be used as a tracer for paclitaxel. (author)

  1. A novel green one-step synthesis of silver nanoparticles using chitosan: catalytic activity and antimicrobial studies

    Science.gov (United States)

    Venkatesham, Maragoni; Ayodhya, Dasari; Madhusudhan, Alle; Veera Babu, Nagati; Veerabhadram, Guttena

    2014-01-01

    Stable silver nanoparticles were synthesized using chitosan acting as both reducing and stabilizing agent without using any toxic chemicals. This reaction was carried out in an autoclave at a pressure of 15 psi and 120 °C temperature by varying the time. The influence of different parameters such as time, change of concentration of silver nitrate and concentration of chitosan on the formation of silver nanoparticles were studied. The synthesized silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared, X-ray diffraction and transmission electron microscopy. The results of catalytic reduction of 4-nitrophenol by sodium borohydride in the presence of green synthesized silver nanoparticles were presented. The antimicrobial activity of silver nanoparticles was tested against Escherichia coli and Micrococcus luteus and was found to be possessing inhibiting property.

  2. Experimental Study of Interfacial Friction in NaBH4 Solution in Microchannel Dehydrogenation Reactor

    International Nuclear Information System (INIS)

    Sodium borohydride (NaBH4) is considered as a secure metal hydride for hydrogen storage and supply. In this study, the interfacial friction of two-phase flow in the dehydrogenation of aqueous NaBH4 solution in a microchannel with a hydraulic diameter of 461 μm is investigated for designing a dehydrogenation chemical reactor flow passage. Because hydrogen gas is generated by the hydrolysis of NaBH4 in the presence of a ruthenium catalyst, two different flow phases (aqueous NaBH4 solution and hydrogen gas) exist in the channel. For experimental studies, a microchannel was fabricated on a silicon wafer substrate, and 100-nm ruthenium catalyst was deposited on three sides of the channel surface. A bubbly flow pattern was observed. The experimental results indicate that the two-phase multiplier increases linearly with the void fraction, which depends on the initial concentration, reaction rate, and flow residence time

  3. Selected scientific articles. (Investigations in the field of hydrides chemistry and mineral raw materials processing)

    International Nuclear Information System (INIS)

    Articles, included in the present book are covering period 1977-2013 y. The main scientific articles in the field of power-consuming substances, mineral raw-materials and wastes reprocessing, including uranium industry wastes are collected. Scientific works on hydrogen chemistry which carried out basically bu U.M. Mirsaidov without co-authors are considered. These works are on aluminium hydrides and borohydrides lanthanides. Besides, author's popular-science articles on research carried out by Academy of Sciences during the period when he was the President of Academy of Sciences of the Republic of Tajikistan (1995-2005) are included. Mineral raw materials and wastes reprocessing results are given as well. The book is intended for engineer and technical staff, those working in the field of hydrogen chemistry, hydrometallurgy workers, engineering chemists as well as for PhD, post graduate students and students of appropriate profiles.

  4. An easy and effective method for radiolabelling of solid lipid nanoparticles

    International Nuclear Information System (INIS)

    Solid lipid nanoparticle (SLN) was successfully radio labelled with 99mTc by using sodium borohydride as a reducing agent. Paclitaxel (PTX) was used as a model anticancer drug for the preparation of drug loaded SLN (PSLN). Paclitaxel is prescribed mainly to treat breast and ovarian cancers, but it is known that various cancer cells including glioma cells can be killed effectively by this drug. Utility of paclitaxel is severely hampered by its high lipophilicity and some adverse effects associated with Cremophor EL, one of the components of marketed paclitaxel formulation (Taxol). Interference of radiocolloids on the biodistribution of lipid nanoparticle can be avoided by this method as both the radiolabelling efficiency and radiochemical purity of the complex was found to be > 95%. This study indicates prepared PSLN may effectively deliver more PTX in brain than the marketed formulation of PTX

  5. Determination of synthesis method of ecstasy based on the basic impurities.

    Science.gov (United States)

    Swist, M; Wilamowski, J; Parczewski, A

    2005-09-10

    MDMA was prepared by five different synthesis routes, i.e. by dissolving metal reduction (Al/Hg), cyanoborohydride reduction (NaBH(3)CN), borohydride reduction in low temperature (NaBH(4)), Leuckart reaction and safrole bromination. MDP-2-P was prepared by two different synthesis methods, i.e. by isosafrole oxidation and MDP-2-nitropropene reduction. Each of the synthesis routes was repeated three times in order to establish variation in qualitative composition of route specific impurities between different batches. The analysis of impurities in MDP-2-nitropropene, MDP-2-P, bromosafrole and MDMA was performed with GC-MS. GC/MS was used also in the analysis of impurities in starting materials: safrole, isosafrole and piperonal. As a result of our study the way of determination of MDMA synthesis route determination based on qualitative composition of impurities is proposed. PMID:15978342

  6. Camphor-mediated synthesis of carbon nanoparticles, graphitic shell encapsulated carbon nanocubes and carbon dots for bioimaging.

    Science.gov (United States)

    Oza, Goldie; Ravichandran, M; Merupo, Victor-Ishrayelu; Shinde, Sachin; Mewada, Ashmi; Ramirez, Jose Tapia; Velumani, S; Sharon, Madhuri; Sharon, Maheshwar

    2016-01-01

    A green method for an efficient synthesis of water-soluble carbon nanoparticles (CNPs), graphitic shell encapsulated carbon nanocubes (CNCs), Carbon dots (CDs) using Camphor (Cinnamomum camphora) is demonstrated. Here, we describe a competent molecular fusion and fission route for step-wise synthesis of CDs. Camphor on acidification and carbonization forms CNPs, which on alkaline hydrolysis form CNCs that are encapsulated by thick graphitic layers and on further reduction by sodium borohydride yielded CDs. Though excitation wavelength dependent photoluminescence is observed in all the three carbon nanostructures, CDs possess enhanced photoluminescent properties due to more defective carbonaceous structures. The surface hydroxyl and carboxyl functional groups make them water soluble in nature. They possess excellent photostability, higher quantum yield, increased absorption, decreased cytotoxicity and hence can be utilized as a proficient bio imaging agent. PMID:26905737

  7. Development of carborane synthons: Synthesis and chemistry of (aminoalkyl)carboranes

    International Nuclear Information System (INIS)

    A number of (aminoalkyl)-1,2-closo-dodecaboranes have been synthesized to provide carboranes with a functional group for covalent incorporation into structures of potential use in the treatment of cancer by boron neutron capture therapy (BNCT). (Phthalimidoalkyl)acetylenes reacted with decaborane to give the corresponding carboranes; removal of the phthalimido group under mild conditions using sodium borohydride in 2-propanol furnished the (aminoalkyl)carboranes which were isolated as their hydrochloride salts. An alternative approach involved the conversion of an (iodoalkyl)- or a ((tosyloxy)alkyl)carborane to the azido derivative which gave the amine on hydrogenation. An effective way of attaching a carborane moiety to thiouracil, which is selectively taken up in melanoma cells, is illustrated by the acylation of two of these amines with thiouracil-5-carboxylic acid

  8. Synthesis and Biological Evaluation of New Imine- and Amino-Chitosan Derivatives

    Directory of Open Access Journals (Sweden)

    Huda E. Abdelwahab

    2015-12-01

    Full Text Available N-substituted chitosan derivatives were synthesized through condensation with a number of selected aryl and heteroaryl aldehydes. The synthesis of the amino-derivatives has been carried out by reductive amination with sodium borohydride as reducing agent. Their structures were characterized by (FT-IR, 1HNMR, and XRD. The antimicrobial activity of Chitosan Schiff’s base (CSB derivatives were investigated against four types of bacteria and two crop-threatening pathogenic fungi, and the results indicated that the antibacterial and antifungal activities of the investigated derivatives are very promising. Additionally, different concentrations of the triazolo-Schiff’s base derivative 3c were used for cytotoxicity screening against Human Breast Adenocarcinoma Cells (MCF-7, Human Colon Carcinoma Cells (HCT-116, and Human Hepatocellular Liver Carcinoma Cells (HepG-2, and the obtained data revealed that the examined compounds have an excellent cell growth inhibitory effects on the cell lines as compared to standard.

  9. Green synthesis, characterization and catalytic activity of palladium nanoparticles by xanthan gum

    Science.gov (United States)

    Santoshi kumari, Amrutham; Venkatesham, Maragoni; Ayodhya, Dasari; Veerabhadram, Guttena

    2015-03-01

    Here, we report the synthesis, characterization and catalytic evaluation of palladium nanoparticles (PdNPs) using xanthan gum, acting as both reducing and stabilizing agent without using any synthetic reagent. The uniqueness of our method lies in its fast synthesis rates using hydrothermal method in autoclave at a pressure of 15 psi and at 120 °C temperature by 10 min time. The formation and size of the PdNPs were characterized by UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. The catalytic activity of PdNPs was evaluated on the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride using spectrophotometry.

  10. The synthesis of iron nickel alloy nanoparticles using a reverse micelle technique

    Science.gov (United States)

    Ban, Irena; Drofenik, Miha; Makovec, Darko

    2006-12-01

    Nanosized Fe 0.2Ni 0.8 particles were prepared by reducing their salts with sodium borohydride (NaBH 4) in cationic water-in-oil (w/o) microemulsions of water/cetyl-trimethyl-amonium bromide (CTAB) and n-butanol/isooctane at 25 °C. According to the TEM and X-ray diffraction analyses, the synthesized particles were around 4-12 nm in size. Due to their nanodimensions, the particles had a primitive cubic (pc) structure rather than the body-centered cubic (BCC) structure of the bulk material. An examination of the synthesis from the reverse micelle reveals that the morphology of the iron-nickel alloy nanoparticles depends mainly on the microemulsion's composition. The magnetization of the nanoparticles was much lower than that of the bulk material, reflecting the influence of the nanodimensions on the particles' magnetizations.

  11. Graphene sheets/cobalt nanocomposites as low-cost/high-performance catalysts for hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei; Hou, Chengyi; Zhang, Qinghong [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Wang, Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Li, Yaogang, E-mail: yaogang_li@dhu.edu.cn [College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China)

    2012-08-15

    The production of clean and renewable hydrogen through the hydrolysis of sodium borohydride has received much attention owing to increasing global energy demands. Graphene sheets/cobalt (GRs/Co) nanocomposites, which are highly efficient catalysts, have been prepared using a one-step solvothermal method in ethylene glycol. Co{sup 2+} salts were converted to Co nanoparticles, which were simultaneously inserted into the graphene layers with the reduction of graphite oxide sheets to GRs. The as-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectra, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and vibrating sample magnetometer. The maximum saturation magnetization value reached 80.8 emu g{sup -1}, meaning they are more suitable for magnet-controlled generation of H{sub 2} than noble metal catalysts. The catalytic activity of the composite was investigated by the hydrolysis of sodium borohydride in aqueous solution both with and without a GRs support. It was found that the high electronic conductive GRs support increased the hydrogen generation rate (about two times) compared with pure cobalt. The improved hydrogen generation rate, low cost and uncomplicated recycling makes the GRs/Co nanocomposites promising candidates as catalysts for hydrogen generation. Highlights: Black-Right-Pointing-Pointer Graphene sheets/cobalt nanocomposites were prepared by a one-step solvothermal method. Black-Right-Pointing-Pointer The maximum saturation magnetization value of the composites reached 80.8 emu g{sup -1}. Black-Right-Pointing-Pointer The graphene support greatly increased the catalytic activity of cobalt. Black-Right-Pointing-Pointer An easily removed, recycled and controlled functional filter was obtained.

  12. 二氢苯骈[c]菲啶类生物碱的制备及其抗乙肝病毒的活性%Preparation of dihydrobenzo[c] phenanthridine alkaloids and evaluation of their anti-hepatitis B virus activity

    Institute of Scientific and Technical Information of China (English)

    吴颖瑞; 方宏; 牙始康; 何瑞杰

    2012-01-01

    二氢苯骈[c]菲啶类生物碱是自然界中一类重要的生物活性成分,但含量很低.利用硼氢化还原方法,对博落回粗提物中的血根碱和白屈菜红碱混合物进行还原、分离,得到了二氢血根碱和二氢白屈菜红碱;并初步评价了其抗乙肝病毒活性.结果表明,利用硼氢化还原方法制备二氢苯骈[c]菲啶类生物碱的产率较高,还原产物具有一定的抗乙肝病毒活性.%Dihydro-benzo[c]phenanthridine alkaloids are a kind of bioactive constituents, but their contents are very low in natural plants. Thus the mixture of sanguinarine and cheleryth-rine primarily extracted from Macleaya cordata (Willd) R B were reduced by sodium boro-hydride and separated into dihydrosanguinarine and dihydrochelerythrine. The anti-hepatitis B virus (HBV) activity of as-obtained dihydrosanguinarine and dihydrochelerythrine was evaluated. It has been found that phenonthridine alkaloids can be obtained in a high yield via the reduction of sanguinarine and chelerythrine by borohydride. As-obtained dihydrosanguinarine and dihydrochelerythrine products have some inhibitory effect against HBV (HBsAg secretions in Hep G2. 2.15 cell line).

  13. Preparation and characterization of electrocatalysts based on palladium for electro-oxidation of alcohols in alkaline medium

    International Nuclear Information System (INIS)

    In this study Pd/C, Au/C, PdAu/C, PdAuPt/C, PdAuBi/C and PdAuIr/C electrocatalysts were prepared by the sodium borohydride reduction method for the electrochemical oxidation of methanol, ethanol and ethylene glycol. This methodology consists in mix an alkaline solution of sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. The electrocatalysts were characterized by energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry. The electrochemical oxidation of the alcohols was studied by chronoamperometry using a thin porous coating technique. The mechanism of ethanol electro-oxidation was studied by Fourier Transformed Infrared (FTIR) in situ. The most effective electrocatalysts were tested in alkaline single cells directly fed with methanol, ethanol or ethylene glycol. Preliminary studies showed that the most suitable atomic composition for preparing the ternary catalysts is 50:45:05. Electrochemical data in alkaline medium show that the electrocatalysts PdAuPt/C (50:45:05) showed the better activity for methanol electro oxidation, while PdAuIr/C was the most active for ethanol oxidation and PdAuBi/C (50:45:05) was the most effective for ethylene glycol oxidation in alkaline medium. These results show that the addition of gold in the composition of electrocatalysts increases their catalytic activities. The spectroelectrochemical FTIR in situ data permitted to conclude that C-C bond is not broken and the acetate is formed. (author)

  14. Thermodynamic modelling of Mg(BH{sub 4}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Pinatel, E.R.; Albanese, E.; Civalleri, B.; Baricco, M.

    2015-10-05

    Highlights: • DFT calculations providing missing thermodynamic data for Mg(BH{sub 4}){sub 2}were performed. • A Calphad assessment of Mg(BH{sub 4}){sub 2} was performed, considering all the available data. • Stable and metastable phase diagrams have been calculated for Mg(BH{sub 4}){sub 2}. • Several dehydrogenation paths of Mg(BH{sub 4}){sub 2} have been analysed and discussed. - Abstract: Application of the Calphad method to the description of thermodynamic properties in complex borohydride-based systems may allow a faster development of hydrogen storage materials. It is, however, limited by the low number of available thermodynamic description for borohydrides in thermodynamic databases. In the present work, a Calphad assessment of Mg(BH{sub 4}){sub 2} has been performed, considering available thermodynamic data. DFT calculations have been performed in order to provide missing thermodynamic data and to calculate the relative stability of the α, β and γ polymorphs. Experimental results have been compared detecting inconsistencies between them. The database obtained has been used to estimate driving forces for several dehydrogenation reactions. The dehydrogenation reaction leading to the formation of MgB{sub 2} and gaseous hydrogen is the most favoured thermodynamically, even if at low temperatures the formation of MgB{sub 12}H{sub 12} is competitive. On the contrary, positive driving forces have been calculated for the decomposition into B{sub 2}H{sub 6} and Mg(B{sub 3}H{sub 8}){sub 2}.

  15. Comparison of two lab-made spray chambers based on MSIS™ for simultaneous metal determination using vapor generation-inductively coupled plasma optical emission spectroscopy.

    Science.gov (United States)

    Fuentes-Cid, A; Villanueva-Alonso, J; Peña-Vázquez, E; Bermejo-Barrera, P

    2012-10-24

    The objective of this study is to evaluate the performance of two lab-made systems based on the Multimode Introduction System (MSIS™) and the modified MSIS™, to generate and introduce vapors of Ag, Cu, Cd, Cu, Ni, Sn, Zn, and also Au in the ICP torch. An univariate procedure was used to select the optimized working conditions (Ar flow, sample, reductant and waste flows, and reagent concentrations). Optimum conditions for working with modified MSIS were: nitric acid concentration 0.35 M, 8-hydroxyquinoline concentration: 40 mg L(-1), sodium borohydride concentration: 1.75% (w/v)+0.4% (w/v) NaOH, argon purge flow to sweep the vapors to the torch: 1.2 L min(-1), sample flow and sodium borohydride flows: 2.3 L min(-1); waste flow: 7.7 mL min(-1). For the optimum working conditions for lab-made MSIS in dual mode the concentration of 8-hydroxyquinoline was 225 mg L(-1), the Ar purge flow was 0.75 L min(-1), and the conventional nebulization flow was 2.3 L min(-1). The sensitivity obtained was higher using the lab-made MSIS than using the lab-made modified MSIS or a forced outlet gas-liquid separator. The limits of detection were better for Au, Cd, Sn than those obtained using conventional nebulization; the measurements were precise (RSDs≤5% in dual mode) and a good accuracy was obtained in the determination of Cd, Cu, Ni and Zn in a wastewater reference material using aqueous calibration and the lab-made MSIS in dual mode. PMID:23036464

  16. Partial characterization of low density lipoprotein preparations isolated from fresh and frozen plasma after radiolabeling by seven different methods

    International Nuclear Information System (INIS)

    Four 99mTc and three 123I labeling methods were evaluated for their suitability to label low density lipoproteins (LDL) for the purpose of scintigraphic biodistribution studies. For 99mTc these methods were: direct incorporation in LDL of 99mTcO4- using sodium dithionite (dithionite method); a method using first N,N-dimethylformamide to prepare a 99mTc-complex reacting with LDL in a subsequent step (DMF method); a technique in which 99mTcO4- is first coupled to a diamide dithiolate derivative of pentanoic acid by reduction with dithionite, followed by coupling of this ligand to LDL (N2S2 method); and a method using sodium borohydride and stannous chloride as reducing agents (borohydride method). The iodination techniques were based on oxidation of I(-)----I+, using iodine monochloride (ICl method), 1,3,4,6-tetrachloro-3,6-diphenylglycoluril (Iodogen method), and N-bromosuccinimide (NBS method) as oxidants. We studied labeling yields, modification of LDL caused by the labeling procedures using agarose-gel electrophoresis, and radiochemical stability of the labeled LDL complex upon incubation in plasma at 37 degrees C for 15 h. We used Sepharose CL6B chromatography to separate LDL from other plasma proteins. We also examined whether LDL isolated from frozen plasma (Pool-LDL) gave results similar to LDL obtained from freshly prepared plasma (Fresh-LDL). Pool-LDL radiolabeled by the dithionite, DMF, NBS, and Iodogen methods lost its label upon incubation with plasma. This also happened with Fresh-LDL when the DMF, NBS and Iodogen methods were used. Upon agarose-gel electrophoresis, no modification of LDL was observed with all methods when the radionuclide/LDL ratio was kept low

  17. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    Science.gov (United States)

    Sljukić, Biljana; Morais, Ana L; Santos, Diogo M F; Sequeira, César A C

    2012-01-01

    Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC's performance. Cell polarization, power density, stability, and durability tests are used in the membranes' evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load. PMID:24958292

  18. Preparation and characterization of electrocatalysts based on palladium for electro-oxidation of alcohols in alkaline medium; Preparacao e caracterizacao de eletrocatalisadores a base de paladio para oxidacao eletroquimica de alcoois em meio alcalino

    Energy Technology Data Exchange (ETDEWEB)

    Brandalise, Michele

    2012-07-01

    In this study Pd/C, Au/C, PdAu/C, PdAuPt/C, PdAuBi/C and PdAuIr/C electrocatalysts were prepared by the sodium borohydride reduction method for the electrochemical oxidation of methanol, ethanol and ethylene glycol. This methodology consists in mix an alkaline solution of sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. The electrocatalysts were characterized by energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry. The electrochemical oxidation of the alcohols was studied by chronoamperometry using a thin porous coating technique. The mechanism of ethanol electro-oxidation was studied by Fourier Transformed Infrared (FTIR) in situ. The most effective electrocatalysts were tested in alkaline single cells directly fed with methanol, ethanol or ethylene glycol. Preliminary studies showed that the most suitable atomic composition for preparing the ternary catalysts is 50:45:05. Electrochemical data in alkaline medium show that the electrocatalysts PdAuPt/C (50:45:05) showed the better activity for methanol electro oxidation, while PdAuIr/C was the most active for ethanol oxidation and PdAuBi/C (50:45:05) was the most effective for ethylene glycol oxidation in alkaline medium. These results show that the addition of gold in the composition of electrocatalysts increases their catalytic activities. The spectroelectrochemical FTIR in situ data permitted to conclude that C-C bond is not broken and the acetate is formed. (author)

  19. Plasmid DNA damage caused by stibine and trimethylstibine

    International Nuclear Information System (INIS)

    Antimony is classified as 'possibly carcinogenic to humans' and there is also sufficient evidence for antimony carcinogenicity in experimental animals. Stibine is a volatile inorganic antimony compound to which humans can be exposed in occupational settings (e.g., lead-acid battery charging). Because it is highly toxic, stibine is considered a significant health risk; however, its genotoxicity has received little attention. For the work reported here, stibine was generated by sodium borohydride reduction of potassium antimony tartrate. Trimethylstibine is a volatile organometallic antimony compound found commonly in landfill and sewage fermentation gases at concentrations ranging between 0.1 and 100 μg/m3. Trimethylstibine is generally considered to pose little environmental or health risk. In the work reported here, trimethylstibine was generated by reduction of trimethylantimony dichloride using either sodium borohydride or the thiol compounds, dithioerythritol (DTE), L-cysteine, and glutathione. Here we report the evaluation of the in vitro genotoxicities of five antimony compounds--potassium antimony tartrate, stibine, potassium hexahydroxyantimonate, trimethylantimony dichloride, and trimethylstibine--using a plasmid DNA-nicking assay. Of these five antimony compounds, only stibine and trimethylstibine were genotoxic (significant nicking to pBR 322 plasmid DNA). We found stibine and trimethylstibine to be about equipotent with trimethylarsine using this plasmid DNA-nicking assay. Reaction of trimethylantimony dichloride with either glutathione or L-cysteine to produce DNA-damaging trimethylstibine was observed with a trimethylantimony dichloride concentration as low as 50 μM and L-cysteine or glutathione concentrations as low as 500 and 200 μM, respectively, for a 24 h incubation

  20. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    Directory of Open Access Journals (Sweden)

    César A. C. Sequeira

    2012-07-01

    Full Text Available Direct borohydride fuel cells (DBFC, which operate on sodium borohydride (NaBH4 as the fuel, and hydrogen peroxide (H2O2 as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S and a cation-exchange membrane (CMI-7000S, are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  1. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  2. Electrochemical hydrogen Storage Systems

    International Nuclear Information System (INIS)

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in the

  3. Final Report: DE- FC36-05GO15063, Fundamental Studies of Advanced High-Capacity, Reversible Metal Hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Craig [University of Hawaii; McGrady, Sean [University of New Brunswick; Severa, Godwin [University of Hawaii; Eliseo, Jennifer [University of Hawaii; Chong, Marina [University of Hawaii

    2015-02-08

    The project was component of the US DOE, Metal Hydride Center of Excellence (MHCoE). The Sandia National Laboratory led center was established to conduct highly collaborative and multi-disciplinary applied R&D to develop new reversible hydrogen storage materials that meet or exceed DOE/FreedomCAR 2010 and 2015 system targets for hydrogen storage materials. Our approach entailed a wide variety of activities ranging from synthesis, characterization, and evaluation of new candidate hydrogen storage materials; screening of catalysts for high capacity materials requiring kinetics enhancement; development of low temperature methods for nano-confinement of hydrides and determining its effects on the kinetics and thermodynamics of hydrides; and development of novel processes for the direct re-hydrogenation of materials. These efforts have resulted in several advancements the development of hydrogen storage materials. We have greatly extended the fundamental knowledge about the highly promising hydrogen storage carrier, alane (AlH₃), by carrying out the first crystal structure determinations and the first determination of the heats of dehydrogenation of β–AlH₃ and γ-AlD₃. A low-temperature homogenous organometallic approach to incorporation of Al and Mg based hydrides into carbon aerogels has been developed that that allows high loadings without degradation of the nano-porous scaffold. Nano-confinement was found to significantly improve the dehydrogenation kinetics but not effect the enthalpy of dehydrogenation. We conceived, characterized, and synthesized a novel class of potential hydrogen storage materials, bimetallic borohydrides. These novel compounds were found to have many favorable properties including release of significant amounts of hydrogen at moderate temperatures (75-190ºC). However, in situ IR studies in tandem with thermal gravimetric analysis have shown that about 0.5 equivalents of diborane are released during the dehydrogenation making re

  4. Synthesis of silver nanoparticles by chemical reduction at various fraction of MSA and their structure characterization

    Energy Technology Data Exchange (ETDEWEB)

    Diantoro, Markus, E-mail: m-diantoror@yahoo.com; Fitrianingsih, Rina, E-mail: m-diantoror@yahoo.com; Mufti, Nandang, E-mail: m-diantoror@yahoo.com; Fuad, Abdulloh, E-mail: m-diantoror@yahoo.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang (UM), Jl. Semarang No. 5 Malang 65145 (Indonesia)

    2014-03-24

    Nanosilver is currently one of the most common engineered nanomaterials and is used in many applications that lead to the release of silver nanoparticles and silver ions into aqueous systems. Nanosilver also possesses enhanced antimicrobial activity and bioavailability that may less environmental risk compared with other manufactured nanomaterials. Described in this research are the synthesis of silver nanoparticle produced by chemical reduction from silver nitrate (AgNO{sub 3}) solution. As a reducing agent, Sodium Borohydride (NaBH{sub 4}) was used and mercaptosuccinic Acid (MSA) as stabilizer to prevent the nanoparticle from aglomerating. It was also used two kinds of solvent, they are water and methanol. In typical experiment MSA was dissolve in methanol with a number of variation of molarity i.e. 0,03 M, 0,06 M, 0,12 M, 0,15 M, and the mixture was kept under vigorous stirring in an ice bath. A solution of silver nitrate of 340 mg in 6,792 ml water was added. A freshly prepared aqueous solution of sodium borohydride (756,6 mL in 100 mL of water) was added drop wisely. The solution was kept for half an hour for stirring and were allowed to settle down in methanol. The obtained samples then characterized by means of x-ray diffractometer, and scanning electron microscopy, as well as transmission electron microscopy to obtain their structures of silver nanoparticles, morphology, and sizes. It is shown that diameter of silver nanoparticle sized about 24.3 nm (Ag@MSA 0.03 M), 20.4 nm (Ag@MSA 0.06 M), 16.8 nm (Ag@MSA 0.12 M), 16.9 nm (Ag@MSA 0.15 M) which was calculated by Scherrer formula by taking the FWHM from fitting to Gaussian. The phases and lattice parameter showed that there is no significant change in its volume by increasing molarity of stabilizer. In contrast, the size of particles is decreasing.

  5. U.S. Department of Energy Hydrogen Storage Cost Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Law, Karen; Rosenfeld, Jeffrey; Han, Vickie; Chan, Michael; Chiang, Helena; Leonard, Jon

    2013-03-11

    The overall objective of this project is to conduct cost analyses and estimate costs for on- and off-board hydrogen storage technologies under development by the U.S. Department of Energy (DOE) on a consistent, independent basis. This can help guide DOE and stakeholders toward the most-promising research, development and commercialization pathways for hydrogen-fueled vehicles. A specific focus of the project is to estimate hydrogen storage system cost in high-volume production scenarios relative to the DOE target that was in place when this cost analysis was initiated. This report and its results reflect work conducted by TIAX between 2004 and 2012, including recent refinements and updates. The report provides a system-level evaluation of costs and performance for four broad categories of on-board hydrogen storage: (1) reversible on-board metal hydrides (e.g., magnesium hydride, sodium alanate); (2) regenerable off-board chemical hydrogen storage materials(e.g., hydrolysis of sodium borohydride, ammonia borane); (3) high surface area sorbents (e.g., carbon-based materials); and 4) advanced physical storage (e.g., 700-bar compressed, cryo-compressed and liquid hydrogen). Additionally, the off-board efficiency and processing costs of several hydrogen storage systems were evaluated and reported, including: (1) liquid carrier, (2) sodium borohydride, (3) ammonia borane, and (4) magnesium hydride. TIAX applied a bottom-up costing methodology customized to analyze and quantify the processes used in the manufacture of hydrogen storage systems. This methodology, used in conjunction with ® software and other tools, developed costs for all major tank components, balance-of-tank, tank assembly, and system assembly. Based on this methodology, the figure below shows the projected on-board high-volume factory costs of the various analyzed hydrogen storage systems, as designed. Reductions in the key cost drivers may bring hydrogen storage system costs closer to this DOE target

  6. Influence of bismuth on the structure and activity of Pt and Pd nanocatalysts for the direct electrooxidation of NaBH{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, Mario; Baranton, Steve [Laboratoire de Catalyse en Chimie Organique, Equipe Electrocatalyse, UMR 6503 CNRS, 40 avenue du recteur Pineau, F-86022 Poitiers Cedex (France); Coutanceau, Christophe, E-mail: christophe.coutanceau@univ-poitiers.f [Laboratoire de Catalyse en Chimie Organique, Equipe Electrocatalyse, UMR 6503 CNRS, 40 avenue du recteur Pineau, F-86022 Poitiers Cedex (France)

    2010-12-15

    In the past few years, borohydrides have gathered a lot of attention as an energy carrier for fuel cell application. Numerous investigations on both hydrogen generation and direct oxidation of NaBH{sub 4} have been published. Nonetheless, in our knowledge, only a few catalysts are capable to completely perform the direct oxidation of NaBH{sub 4} at low potentials without hydrogen evolution. In this work, carbon supported Pd{sub 1-x}Bi{sub x}/C and Pt{sub 1-x}Bi{sub x}/C nanocatalysts were synthesized by a 'water in oil' microemulsion method. The influence of surface modifications of Pt and Pd by Bi on the electrooxidation of sodium borohydride in alkaline media was evaluated. Physical and electrochemical methods were applied to characterize the structure and surface of the synthesized catalysts. It was verified that bismuth is present at the surface of the bimetallic catalysts and that hydrogen adsorption/desorption reactions are strongly limited on Pt and Pd surfaces with high bismuth coverage. Although the onset potential for NaBH{sub 4} oxidation on Pd{sub x}Bi{sub 1-x}/C catalysts is ca. 0.2 V higher than that for Pd/C, the presence of bismuth on palladium surface influences the reaction mechanism, limiting hydrogen evolution and oxidation in the case of Pd{sub 0.8}Bi{sub 0.2} catalyst. On Pt{sub 0.9}Bi{sub 0.1} catalyst the onset potential remains unchanged comparing to Pt/C and negligible hydrogen evolution was observed in the whole potential range where the catalyst is active. The number of exchanged electrons was calculated using the Koutecky-Levich equation and it was found that for Pt{sub 0.9}Bi{sub 0.1} catalyst, ca. 8 electrons are exchanged per BH{sub 4}{sup -} ion at low potentials. The presented results are remarkable evidencing that NaBH{sub 4} can be directly oxidized at low potentials with high energy efficiency.

  7. Synthesis of silver nanoparticles by chemical reduction at various fraction of MSA and their structure characterization

    International Nuclear Information System (INIS)

    Nanosilver is currently one of the most common engineered nanomaterials and is used in many applications that lead to the release of silver nanoparticles and silver ions into aqueous systems. Nanosilver also possesses enhanced antimicrobial activity and bioavailability that may less environmental risk compared with other manufactured nanomaterials. Described in this research are the synthesis of silver nanoparticle produced by chemical reduction from silver nitrate (AgNO3) solution. As a reducing agent, Sodium Borohydride (NaBH4) was used and mercaptosuccinic Acid (MSA) as stabilizer to prevent the nanoparticle from aglomerating. It was also used two kinds of solvent, they are water and methanol. In typical experiment MSA was dissolve in methanol with a number of variation of molarity i.e. 0,03 M, 0,06 M, 0,12 M, 0,15 M, and the mixture was kept under vigorous stirring in an ice bath. A solution of silver nitrate of 340 mg in 6,792 ml water was added. A freshly prepared aqueous solution of sodium borohydride (756,6 mL in 100 mL of water) was added drop wisely. The solution was kept for half an hour for stirring and were allowed to settle down in methanol. The obtained samples then characterized by means of x-ray diffractometer, and scanning electron microscopy, as well as transmission electron microscopy to obtain their structures of silver nanoparticles, morphology, and sizes. It is shown that diameter of silver nanoparticle sized about 24.3 nm (Ag@MSA 0.03 M), 20.4 nm (Ag@MSA 0.06 M), 16.8 nm (Ag@MSA 0.12 M), 16.9 nm (Ag@MSA 0.15 M) which was calculated by Scherrer formula by taking the FWHM from fitting to Gaussian. The phases and lattice parameter showed that there is no significant change in its volume by increasing molarity of stabilizer. In contrast, the size of particles is decreasing

  8. A new method to radiolabel fulvic acids with tritium for the purpose of tracing organic matter transport at low concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Tinnacher, R.M.; Honeyman, B.D. [Environmental Science and Engineering Division, Colorado School of Mines, Golden, CO 80401, (United States); Leenheer, J.A. [U.S. Geological Survey, Denver Federal Center, Denver, CO 80225 (United States)

    2005-07-01

    Full text of publication follows: It is increasingly evident that reactive transport models for radionuclides need to include the effects of natural organic ligands, such as bacterial exudates and humic and fulvic acids. Understanding the role of such ligands in radionuclide transport requires an ability to track ligand concentrations in time and space with an analytical resolution similar to that of the target radionuclide. Unfortunately, for many systems of interest for radioactive waste disposal and performance assessment, organic ligand concentrations are quite low (e.g., mg C/ L or less). Radiolabeling organic ligands can provide a means of tracing such species at low levels and for relatively low cost. Currently-used labeling methods, however, show some limitations with respect to the chemical stability of the radiolabel, the ability to produce high label specific activities and method reproducibility. In the procedure that we will describe, fulvic acid is radiolabeled with tritium by its reduction with tritiated sodium borohydride (NaBH{sub 4}) at alkaline pH and slightly elevated temperatures. The reactant selectively reduces the carbonyl groups of aromatic and aliphatic ketones as well as quinones. This results in the formation of tritium-labeled secondary alcohols. After completion of the labeling reaction, aerobically unstable reduction products of quinones and aromatic ketones are re-oxidized under controlled experimental conditions during an aeration step. Labeling efficiency in terms of reduced reactive fulvic acid groups is in the range of 100 percent with equal weights of fulvic acid and NaBH{sub 4} in the reaction solution. This yields specific activities on the order of 50 to 100 {mu}Ci / mg fulvic acid. A quasi-chemical model of the labeling process allows the accurate prediction of the labeling efficiency based on a simplified mass action expression for the labeling reaction and the mass balance equations for fulvic acid and sodium borohydride

  9. Synthesis of tert-Butyl-4-Methyl-3-Oxopiperidine-1-Carboxylate%1-叔丁羰基-4-甲基-3-哌啶酮的合成研究

    Institute of Scientific and Technical Information of China (English)

    郝宝玉; 张维汉; 耿秀丽; 赵倩; 陈新志

    2011-01-01

    1-叔丁羰基-4-甲基-3-哌啶酮是合成新型蛋白酪氨酸激酶Jak3抑制剂CP-690550的重要中间体,今以廉价易得的3-羟基-4-甲基吡啶和氯苄为原料,经过SN2取代反应,再经硼氢化还原生成N-苄基-3-羟基-4-甲基哌啶.过程中考察了溶剂对实验的影响,确定最佳溶剂为3.0 mol·L-1 NaOH水溶液,后经Jones氧化,Pd/C催化脱苄及酰基化反应,得到目标产物1-叔丁羰基-4-甲基-3-哌啶酮,总收率达80.2%.该工艺较现有工艺具有反应原料易得,工艺简单,收率高,较易工业化等优点.%tert-Butyl 4-methyl-3-oxopiperidine-l-carboxylate is an important intermediate in the synthesis of the novel protein tyrosine kinase Jak3 inhibitor-CP-690550. In this article, an efficient approach to the synthesis of this interesting compound was proposed. The proposed synthesis process consists of a series of steps: starting from the easy available reagent 4-methylpyridinium, going through the SN2 substitution with benzyl chloride to offer l-benzyl-3-hydroxy-4-methylpyridium chloride with high yield, and then defining the suitable solvent species and its reasonable concentration for the borohydride reduction with sodium borohydride to provide N-benzyl-3-hydroxy- 4- methylpiperidine, consequently, oxidation by Jones reagent under mild temperature to give N-benzyl-3-oxo-4-methylpiperdine, and at last, debenzylation with Pd/C catalyst and acylation to obtain the target product /erf-butyl 4-methyl-3-oxopiperidine-l-carboxylate. The total yield can reach 80.2% by using the proposed method. Compared with the existing process, the proposed method has the advantages of easily obtained raw materials, simple in operation and suitable for industrial scale-up.

  10. Chemical Hydrogen Storage Using Polyhedral Borane Anions and Aluminum-Ammonia-Borane Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, M. Frederick; Jalisatgi, Satish S.; Safronov, Alexander V.; Lee, Han Beak; Wu, Jianguo

    2010-10-01

    Phase 1. Hydrolysis of borohydride compounds offer the potential for significant hydrogen storage capacity, but most work to date has focused on one particular anion, BH4-, which requires high pH for stability. Other borohydride compounds, in particular polyhedral borane anions offer comparable hydrogen storage capacity without requiring high pH media and their long term thermal and hydrolytic stability coupled with non-toxic nature make them a very attractive alternative to NaBH4. The University of Missouri project provided the overall program focal point for the investigation of catalytic hydrolysis of polyhedral borane anions for hydrogen release. Due to their inherent stability, a transition metal catalyst was necessary for the hydrolysis of polyhedral borane anions. Transition metal ions such as cobalt, nickel, palladium and rhodium were investigated for their catalytic activity in the hydrolysis of nido-KB11H14, closo-K2B10H10, and closo-K2B12H12. The rate of hydrolysis follows first-order kinetics with respect to the concentration of the polyhedral borane anion and surface area of the rhodium catalyst. The rate of hydrolysis depends upon a) choice of polyhedral borane anion, c) concentration of polyhedral borane anion, d) surface area of the rhodium catalyst and e) temperature of the reaction. In all cases the yield of hydrogen was 100% which corresponds to ~7 wt% of hydrogen (based on material wt%). Phase 2. The phase 2 of program at the University of Missouri was focused upon developing aluminum ammonia-boranes (Al-AB) as chemical hydrogen storage materials, specifically their synthesis and studies of their dehydrogenation. The ammonia borane molecule (AB) is a demonstrated source of chemically stored hydrogen (19.6 wt%) which meets DOE performance parameters except for its regeneration from spent AB and elemental hydrogen. The presence of an aluminum center bonded to multiple AB residues might combine the efficiency of AB dehydrogenation with an aluminum

  11. A ternary Cu2O-Cu-CuO nanocomposite: a catalyst with intriguing activity.

    Science.gov (United States)

    Sasmal, Anup Kumar; Dutta, Soumen; Pal, Tarasankar

    2016-02-21

    In this work, the syntheses of Cu2O as well as Cu(0) nanoparticle catalysts are presented. Copper acetate monohydrate produced two distinctly different catalyst particles with varying concentrations of hydrazine hydrate at room temperature without using any surfactant or support. Then both of them were employed separately for 4-nitrophenol reduction in aqueous solution in the presence of sodium borohydride at room temperature. To our surprise, it was noticed that the catalytic activity of Cu2O was much higher than that of the metal Cu(0) nanoparticles. We have confirmed the reason for the exceptionally high catalytic activity of cuprous oxide nanoparticles over other noble metal nanoparticles for 4-nitrophenol reduction. A plausible mechanism has been reported. The unusual activity of Cu2O nanoparticles in the reduction reaction has been observed because of the in situ generated ternary nanocomposite, Cu2O-Cu-CuO, which rapidly relays electrons and acts as a better catalyst. In this ternary composite, highly active in situ generated Cu(0) is proved to be responsible for the hydride transfer reaction. The mechanism of 4-nitrophenol reduction has been established from supporting TEM studies. To further support our proposition, we have prepared a compositionally similar Cu2O-Cu-CuO nanocomposite using Cu2O and sodium borohydride which however displayed lower rate of reduction than that of the in situ produced ternary nanocomposite. The evolution of isolated Cu(0) nanoparticles for 4-nitrophenol reduction from Cu2O under surfactant-free condition has also been taken into consideration. The synthetic procedures of cuprous oxide as well as its catalytic activity in the reduction of 4-nitrophenol are very convenient, fast, cost-effective, and easily operable in aqueous medium and were followed spectrophotometrically. Additionally, the Cu2O-catalyzed 4-nitrophenol reduction methodology was extended further to the reduction of electronically diverse nitroarenes. This

  12. Metal interferences and their removal prior to the determination of As(T) and As(III) in acid mine waters by hydride generation atomic absorption spectrometry

    Science.gov (United States)

    McCleskey, R. Blaine; Nordstrom, D. Kirk; Ball, James W.

    2003-01-01

    Hydride generation atomic absorption spectrometry (HGAAS) is a sensitive and selective method for the determination of total arsenic (arsenic(III) plus arsenic(V)) and arsenic(III); however, it is subject to metal interferences for acid mine waters. Sodium borohydride is used to produce arsine gas, but high metal concentrations can suppress arsine production. This report investigates interferences of sixteen metal species including aluminum, antimony(III), antimony(V), cadmium, chromium(III), chromium(IV), cobalt, copper(II), iron(III), iron(II), lead, manganese, nickel, selenium(IV), selenium(VI), and zinc ranging in concentration from 0 to 1,000 milligrams per liter and offers a method for removing interfering metal cations with cation exchange resin. The degree of interference for each metal without cation-exchange on the determination of total arsenic and arsenic(III) was evaluated by spiking synthetic samples containing arsenic(III) and arsenic(V) with the potential interfering metal. Total arsenic recoveries ranged from 92 to 102 percent for all metals tested except antimony(III) and antimony(V) which suppressed arsine formation when the antimony(III)/total arsenic molar ratio exceeded 4 or the antimony(V)/total arsenic molar ratio exceeded 2. Arsenic(III) recoveries for samples spiked with aluminum, chromium(III), cobalt, iron(II), lead, manganese, nickel, selenium(VI), and zinc ranged from 84 to 107 percent over the entire concentration range tested. Low arsenic(III) recoveries occurred when the molar ratios of metals to arsenic(III) were copper greater than 120, iron(III) greater than 70, chromium(VI) greater than 2, cadmium greater than 800, antimony(III) greater than 3, antimony(V) greater than 12, or selenium(IV) greater than 1. Low recoveries result when interfering metals compete for available sodium borohydride, causing incomplete arsine production, or when the interfering metal oxidizes arsenic(III). Separation of interfering metal cations using

  13. Spontaneous synthesis of gold nanoparticles on gum arabic-modified iron oxide nanoparticles as a magnetically recoverable nanocatalyst.

    Science.gov (United States)

    Wu, Chien-Chen; Chen, Dong-Hwang

    2012-01-01

    A novel magnetically recoverable Au nanocatalyst was fabricated by spontaneous green synthesis of Au nanoparticles on the surface of gum arabic-modified Fe3O4 nanoparticles. A layer of Au nanoparticles with thickness of about 2 nm was deposited on the surface of gum arabic-modified Fe3O4 nanoparticles, because gum arabic acted as a reducing agent and a stabilizing agent simultaneously. The resultant magnetically recoverable Au nanocatalyst exhibited good catalytic activity for the reduction of 4-nitrophenol with sodium borohydride. The rate constants evaluated in terms of pseudo-first-order kinetic model increased with increase in the amount of Au nanocatalyst or decrease in the initial concentration of 4-nitrophenol. The kinetic data suggested that this catalytic reaction was diffusion-controlled, owing to the presence of gum arabic layer. In addition, this nanocatalyst exhibited good stability. Its activity had no significant decrease after five recycles. This work is useful for the development and application of magnetically recoverable Au nanocatalyst on the basis of green chemistry principles. PMID:22713480

  14. Catalytic reduction of 4-nitrophenol by magnetically recoverable Au nanocatalyst.

    Science.gov (United States)

    Chang, Yang-Chuang; Chen, Dong-Hwang

    2009-06-15

    A novel magnetically recoverable Au nanocatalyst was fabricated by the simple adsorption-reduction of Au(III) ions on chitosan-coated iron oxide magnetic nanocarrier. Au nanoparticles with a mean diameter of 3.14 nm were well loaded on the surface of magnetic nanocarrier because chitosan layer provided an effective driving force in the formation and stabilization of Au nanoparticles. The resultant magnetically recoverable Au nanocatalyst exhibited excellent catalytic activity to the reduction of 4-nitrophenol (4-NP) with sodium borohydride. The rate constants evaluated in terms of pseudo-first-order kinetic model increased with increasing the amount of Au nanocatalyst, decreasing the initial 4-NP concentration, and increasing the temperature. Also, the kinetic data suggested that this catalytic reaction was diffusion controlled owing to the presence of chitosan layer. In addition, catalyst reuse showed no trace of deactivation or poisoning during the catalytic and separation processes, revealing the stable nature and good catalytic ability of this nanocatalyst. PMID:19022566

  15. Catalytic activity of silicon nanowires decorated with silver and copper nanoparticles

    Science.gov (United States)

    Amdouni, Sonia; Coffinier, Yannick; Szunerits, Sabine; Zaïbi, Mohammed Ali; Oueslati, Meherzi; Boukherroub, Rabah

    2016-01-01

    The paper reports on the elaboration of silicon nanowires decorated with silver (SiNWs-Ag NPs) or copper (SiNWs-Cu NPs) nanoparticles and the investigation of their catalytic properties for the reduction of 4-nitrophenol to 4-aminophenol. The SiNW arrays were produced through chemical etching of crystalline silicon in HF/AgNO3 aqueous solution. The metal nanoparticles were deposited on the SiNW substrates through chemical bath immersion in a metal salt/hydrofluoric acid aqueous solution. The SiNWs decorated with Ag NPs and Cu NPs were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). The catalytic activity of the SiNWs loaded with metal nanoparticles was evaluated for the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride (NaBH4). The substrates exhibited good catalytic performance toward nitrophenol with a full reduction in less than 30 s for the SiNWs-Cu NPs.

  16. Preparation of kapok-polyacrylonitrile core-shell composite microtube and its application as gold nanoparticles carrier

    Science.gov (United States)

    Fan, Haosen; Yu, Xiaolan; Long, Yuhua; Zhang, Xiaoyan; Xiang, Haifan; Duan, Chunting; Zhao, Ning; Zhang, Xiaoli; Xu, Jian

    2012-01-01

    In this article, a new catalyst carrier kapok-polyacrylonitrile (PAN) composite microtube was fabricated based on the natural kapok fiber. Kapok-PAN core-shell composite microtubes were prepared by a cetyltrimethylammonium bromide (CTAB) assisted self-assembly method. The formation mechanism was proposed and the influence of the concentration of acrylonitrile (AN) monomer and CTAB on the morphology of kapok-PAN was investigated. The hydrophilicity and specific surface area of kapok microtubes were improved because of the outside PAN coating constructed by the PAN nanoparticles aggregation. Gold nanoparticles (Au NPs) were immobilized on the surface of kapok-PAN microtubes via in situ reduction of chloroauric acid (HAuCl4) by sodium borohydride (NaBH4). The obtained Au NPs with mean diameter of 3.1 nm were well dispersed without any aggregation. In addition, kapok-PAN-Au composites exhibited excellent catalytic activity and could be recovered easily without apparent decrease of activity, as demonstrated via the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. The kapok-PAN composite microtubes may be one of the promising supporting materials in developing low-cost, high-efficiency catalyst carriers for metal NPs.

  17. Role of pH in the synthesis of 3-aminopropyl trimethoxysilane stabilized colloidal gold/silver and their alloy sols and their application to catalysis

    International Nuclear Information System (INIS)

    Research highlights: → Synthesis of nano-alloy dispersions of Au and Ag in aminosilicate sol. → pH conditions on chemical stability of Au, Ag and their alloy sols were optimized. → The stable alloy sols catalyze the reduction of 4-nitrophenol to 4-aminophenol. → Catalytic rate constants were evaluated from UV-visible spectroscopy. - Abstract: A general method for the synthesis of nano-alloy dispersions of noble metals like Au and Ag in organically modified aminosilicate sol is presented with an emphasis on the influence of pH on the sol stability. The alloys of Au-Ag were synthesized by co-reduction of solutions of gold and silver salts using borohydride as the reducing agent at a suitable pH in the medium containing 3-aminopropyltrimethoxysilane (APS) stabilizer. Organosilanes with amine functional group have multiple roles in the formation of stable sols such as the formation of siloxane network structures by hydrolysis and condensation and the interaction of amino group with metal ions in solution electrostatically. Mono metal and alloy sols were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy. The stable alloy sols were found to catalyze the chemical reduction of 4-nitrophenol to 4-aminophenol and the catalytic rate constants were evaluated from UV-vis spectroscopy.

  18. Eco-friendly synthesis of silver and gold nanoparticles with enhanced bactericidal activity and study of silver catalyzed reduction of 4-nitrophenol

    Science.gov (United States)

    Naraginti, Saraschandra; Sivakumar, A.

    2014-07-01

    The present study reports a simple and robust method for synthesis of silver and gold nanoparticles using Coleus forskohlii root extract as reducing and stabilizing agent. Stable silver nanoparticles (AgNPs) and gold nanopoarticles (AuNPs) were formed on treatment of an aqueous silver nitrate (AgNO3) and chloroauric acid (HAuCl4) solutions with the root extract. The nanoparticles obtained were characterized by UV-Visible spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). UV-Vis and TEM analysis indicate that with higher quantities of root extract, the interaction is enhanced leading to size reduction of spherical metal nanoparticles. XRD confirms face-centered cubic phase and the diffraction peaks can be attributed to (1 1 1), (2 0 0), (2 2 2) and (3 1 1) planes for these nanoparticles. These synthesized Ag and Au nanoparticles were found to exhibit excellent bactericidal activity against clinically isolated selected pathogens such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The synthesized AgNPs were also found to function as an efficient green catalyst in the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride, which was apparent from the periodical color change from bright yellow to colorless, after the addition of AgNPs.

  19. Extracellular synthesis of mycogenic silver nanoparticles by Cylindrocladium floridanum and its homogeneous catalytic degradation of 4-nitrophenol

    Science.gov (United States)

    Narayanan, Kannan Badri; Park, Hyun Ho; Sakthivel, Natarajan

    2013-12-01

    Green synthesis of extracellular mycogenic silver nanoparticles using the fungus, Cylindrocladium floridanum is reported. The synthesized mycogenic silver nanoparticles were characterized using UV-Vis absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. The nanoparticles exhibit fcc structure with Bragg's reflections of (1 1 1), (2 0 0), (2 2 0) and (3 1 1) was evidenced by XRD pattern, high-resolution TEM lattice fringes and circular rings in selected-area electron diffraction (SAED) pattern. The morphology of nanoparticles was roughly spherical in shape with an average size of ca. 25 nm. From FTIR spectrum, it was found that the biomolecules with amide I and II band were involved in the stabilization of nanoparticles. These mycogenic silver nanoparticles exhibited the homogeneous catalytic potential in the reduction of pollutant, 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride, which followed a pseudo-first-order kinetic model. Thus, the synthesis of metal nanoparticles using sustainable microbial approach opens up possibilities in the usage of mycogenic metal nanoparticles as catalysts in various chemical reactions.

  20. Role of pH in the synthesis of 3-aminopropyl trimethoxysilane stabilized colloidal gold/silver and their alloy sols and their application to catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Harish, S.; Sabarinathan, R. [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630 006 (India); Joseph, James, E-mail: jameskavalam@yahoo.com [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630 006 (India); Phani, K.L.N. [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2011-05-16

    Research highlights: {yields} Synthesis of nano-alloy dispersions of Au and Ag in aminosilicate sol. {yields} pH conditions on chemical stability of Au, Ag and their alloy sols were optimized. {yields} The stable alloy sols catalyze the reduction of 4-nitrophenol to 4-aminophenol. {yields} Catalytic rate constants were evaluated from UV-visible spectroscopy. - Abstract: A general method for the synthesis of nano-alloy dispersions of noble metals like Au and Ag in organically modified aminosilicate sol is presented with an emphasis on the influence of pH on the sol stability. The alloys of Au-Ag were synthesized by co-reduction of solutions of gold and silver salts using borohydride as the reducing agent at a suitable pH in the medium containing 3-aminopropyltrimethoxysilane (APS) stabilizer. Organosilanes with amine functional group have multiple roles in the formation of stable sols such as the formation of siloxane network structures by hydrolysis and condensation and the interaction of amino group with metal ions in solution electrostatically. Mono metal and alloy sols were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy. The stable alloy sols were found to catalyze the chemical reduction of 4-nitrophenol to 4-aminophenol and the catalytic rate constants were evaluated from UV-vis spectroscopy.

  1. In situ synthesized gold nanoparticles in hydrogels for catalytic reduction of nitroaromatic compounds

    Science.gov (United States)

    Wu, Xiao-Qiong; Wu, Xing-Wen; Huang, Qing; Shen, Jiang-Shan; Zhang, Hong-Wu

    2015-03-01

    Developing hydrogel systems featured by catalytic active is of importance to construct highly effective platforms for removing environmental pollutants/hazardous substances or for bio-/chemosensing. Reported herein are our recent finding that Au nanoparticles could be in situ prepared in chitosan-AuIII hydrogel system via photoreduction, and the as-prepared Au nanoparticles could be employed for the catalytic reduction of a series of nitroaromatic compounds by sodium borohydride (NaBH4). Experimental conditions of synthesizing Au nanoparticles, including pH, concentration of AuIII, and light irradiation time were systematically investigated. The as-prepared Au nanoparticles were characterized by UV-vis absorption spectroscopy, X-ray diffraction (XRD), transmission and field emission scanning electron microscopy (TEM and FESEM). This is the first example for in situ formed metal nanoparticles in chitosan hydrogel systems via photoreduction. The effectiveness of the as-prepared Au nanoparticles as nanocatalysts was evaluated by employing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 as a model reaction. The catalytic reduction reaction was found to be very efficient and to follow a pseudo-first-order kinetics. The as-prepared Au nanoparticles demonstrated good reusability and stability. The reduction of a series of other nitroaromatic compounds including highly explosives 2,4,6-trinitrophenol (2,4,6-tNP) and 2,4,6-trinitrotoluene (2,4,6-tNT) was achieved by means of this catalytic system.

  2. Kinetic analysis of the reduction of 4-nitrophenol catalyzed by Au/Pd nanoalloys immobilized in spherical polyelectrolyte brushes.

    Science.gov (United States)

    Gu, Sasa; Lu, Yan; Kaiser, Julian; Albrecht, Martin; Ballauff, Matthias

    2015-11-14

    We present a detailed study of the catalytic activity of Au/Pd nanoalloys with Au : Pd molar ratio 75 : 25 synthesized using spherical polyelectrolyte brushes (SPB) as carrier system. The reduction of 4-nitrophenol (Nip) by sodium borohydride (BH4(-)) has been used as a model reaction. This reaction proceeds in two steps: 4-nitrophenol is first reduced to 4-hydroxylaminophenol which in a second step is reduced to the final product 4-aminophenol. Both steps of the reaction proceed on the surface of the nanoparticles (Langmuir-Hinshelwood-mechanism). We use this model to analyze the experimental data obtained by catalysis with the Au/Pd-nanoalloys. Good agreements between theory and experiments were found up to 30% conversion of Nip. The kinetic parameters were compared with the data derived from neat Au and Pd nanoparticles immobilized in the same SPB carrier system. The addition of 25% molar ratio of Pd to the nanoalloys increases the reaction rate of the first step nearly 10 times compared with that of SPB-Au and 60 times compared with that of SPB-Pd. Analysis of the nanoalloy by high-resolution transmission electron microscopy suggests that the surface defects of the nanoalloys play an important role for the enhanced catalytic activity. PMID:25790094

  3. Synthesis, characterization, optical and antimicrobial studies of polyvinyl alcohol-silver nanocomposites

    Science.gov (United States)

    Mahmoud, K. H.

    2015-03-01

    Silver nanoparticles (Ag NPs) were synthesized by chemical reduction of silver salt (AgNO3) through sodium borohydride. The characteristic surface plasmon resonance band located at around 400 nm in the UV-Visible absorption spectrum confirmed the formation of Ag nanoparticles. Polyvinyl alcohol-silver (PVA-Ag) nanocomposite films were prepared by the casting technique. The morphology and interaction of PVA with Ag NPs were examined by transmission electron microscopy and FTIR spectroscopy. Optical studies show that PVA exhibited indirect allowed optical transition with optical energy gap of 4.8 eV, which reduced to 4.45 eV under addition of Ag NPs. Optical parameters such as refractive index, complex dielectric constant and their dispersions have been analyzed using Wemple and DiDomenco model. Color properties of the nanocomposites are discussed in the framework of CIE L∗u∗v∗ color space. The antimicrobial activity of the nanocomposite samples was tested against Gram positive bacteria (Staphylococcus aureus NCTC 7447 &Bacillus subtillis NCIB 3610), Gram negative bacteria (Escherichia coli, NTC10416 &Pseudomonas aeruginosa NCIB 9016) and fungi (Aspergillus niger Ferm - BAM C-21) using the agar diffusion technique. The antimicrobial study showed that PVA has moderate antibacterial activity against B. subtillis and the 0.04 wt% Ag NPs composite sample effect was strong against S. aureus.

  4. 稳定分散的纳米银溶胶的制备及其表征%Preparation and Characterization of Stable Dispersive Colloidal Silver Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    王悦辉; 周济; 王婷

    2007-01-01

    Stable aqueous dispersive colloidal Ag nanoparticles were prepared by reducing silver nitrate with sodium borohydride in the presence of 3-mercaptopropionic acid. The formation process of the Ag nanoparticles was investigated by UV-Visible spectroscopy and transmission electron microscopy. The results show that the spherical and rodlike particles and aggregates are formed in the initial stage of the reaction, then the rodlike particles and aggregates are gradually decomposed into small Spherical particles, and the final obtained Ag nanoparticles with an average size of 8 nm are in uniform shapes and narrow size distribution, and the colloid remains stable for more than one month, which makes it convenient for use in practice. The presence of capping agent plays an extra role over nanoparticles stabilization and morphology.The presence of capping agent on the surface of Ag nanoparticle is confirmed by the X-ray photoelectron spectroscopy. It is found that Ag nanoparticles are negatively charged in alkaline condition, whereas they are positively charged in acid condition. Electrosteric effect is responsible for their long-term stability.

  5. The hydrogenation of benzene ring catalyzed by supported ruthenium complex using 2-viny1 pyridine copolymer beads as ligands%共聚物配体钌配合物的苯环催化加氢性能研究

    Institute of Scientific and Technical Information of China (English)

    石秀丽

    2006-01-01

    采用XPS等分析手段证实了2-乙烯基吡啶和甲基丙烯酸乙二醇双醋的交联共聚物小球可作为配体与钌形成配合物,该配合经硼氢化钠还原后生成加氢催化剂PVMRu*,其对苯环(苯、苯酚)催化剂加氢的性能良好,所生成产物的选择性高.实验结果表明:温度、压力及搅拌速度的提高均有利于提高反应的活性.%The hydrogenation of benzene to cyclohexane over 2-vinyl pyridine and 1,2-(methacrylate) glycol cross-linked copolymer beads were used as ligands to form the corresponding ruthenium complex, the subsequent reduction of which with sodium borohydride displayed good catalytic properties in hydrogenation of benzene ring . The experimental results showed that the catalytic activity can be enhanced with the increase in temperature , pressure and stirring rate of the reaction system.

  6. DDT degradation efficiency and ecotoxicological effects of two types of nano-sized zero-valent iron (nZVI) in water and soil.

    Science.gov (United States)

    El-Temsah, Yehia S; Sevcu, Alena; Bobcikova, Katerina; Cernik, Miroslav; Joner, Erik J

    2016-02-01

    Nano-scale zero-valent iron (nZVI) has been conceived for cost-efficient degradation of chlorinated pollutants in soil as an alternative to e.g permeable reactive barriers or excavation. Little is however known about its efficiency in degradation of the ubiquitous environmental pollutant DDT and its secondary effects on organisms. Here, two types of nZVI (type B made using precipitation with borohydride, and type T produced by gas phase reduction of iron oxides under H2) were compared for efficiency in degradation of DDT in water and in a historically (>45 years) contaminated soil (24 mg kg(-1) DDT). Further, the ecotoxicity of soil and water was tested on plants (barley and flax), earthworms (Eisenia fetida), ostracods (Heterocypris incongruens), and bacteria (Escherichia coli). Both types of nZVI effectively degraded DDT in water, but showed lower degradation of aged DDT in soil. Both types of nZVI had negative impact on the tested organisms, with nZVI-T giving least adverse effects. Negative effects were mostly due to oxidation of nZVI, resulting in O2 consumption and excess Fe(II) in water and soil. PMID:26598990

  7. Electrical and Thermal Behavior of Copper-Epoxy Nanocomposites Prepared via Aqueous to Organic Phase Transfer Technique

    Directory of Open Access Journals (Sweden)

    N. H. Mohd Hirmizi

    2012-01-01

    Full Text Available The preparation, electrical, and thermal behaviors of copper-epoxy nanocomposites are described. Cetyltrimethylammonium bromide- (CTAB- stabilized copper (Cu particles were synthesized via phase transfer technique. Isopropanol (IPA, sodium borohydride (NaBH4, and toluene solution of diglycidyl ether of bisphenol A (DGEBA were used as transferring, reducing agent, and the organic phase, respectively. The UV-Vis absorbance spectra of all the sols prepared indicate that the presence of Cu particles with the particles transfer efficiency is ≥97%. The amount, size, and size distribution of particles in the organosol were dependent on the content of organic solute in the organosol. The composites were obtained upon drying the organosols and these were then subjected to further studies on the curing, thermal, and electrical characteristic. The presence of Cu fillers does not significantly affect the completeness of the composite curing process and only slightly reduce the thermal stability of the composites that is >300°C. The highest conductivity value of the composites obtained is 3.06×10-2 S cm-1.

  8. 3,3,5-Trimethylcyclohexanols and derived esters: green synthetic procedures, odour evaluation and in vitro skin cytotoxicity assays.

    Science.gov (United States)

    Gambaro, R; Villa, C; Baldassari, S; Mariani, E; Parodi, A; Bassi, A M

    2006-12-01

    The alcohols 3,3,5-trimethylcyclohexanols (cis, trans epimers, cosmetic fragrance) and some derived esters, potential and well-known actives in the cosmetic field, such as Homosalate, were synthesized using fast solvent-free methodologies with the aim of renewing and simplifying the conventional procedures. The alcohols were prepared by reduction of 3,3,5-trimethylcyclohexanone (dihydroisophorone) with sodium borohydride/alumina in solid state. The esters from propanoic, butanoic, octanoic, 10-undecenoic, cyclopropanecarboxylic, mandelic and salicylic acids were synthesized with microwave-mediated solvent-free procedures under acidic and basic catalysis. Several experiments were carried out to study advantages and limits of the selected methodologies and the results are reported. Microwave irradiation was carried out using a scientific monomode reactor. In order to evaluate the cosmetic interest of the studied compounds, the sweet-scented substances were submitted to an odour evaluation test; the most promising fragrances and the ester from 10-undecenoic acid, as an example of lipophilic derivatives, were tested to assess their in vitro skin toxicity. Résumé PMID:18489288

  9. Optimizing the design and synthesis of supported silver nanoparticles for low cost water disinfection.

    Science.gov (United States)

    He, Di; Kacopieros, Maritsa; Ikeda-Ohno, Atsushi; Waite, T David

    2014-10-21

    Silver nanoparticles (AgNPs) were successfully synthesized and impregnated on silica using chemical reduction methods. XPS and Ag K-edge XANES analysis revealed that the impregnation of AgNPs onto silica using a chitosan + sodium borohydride (NaBH4) method results in higher silver loading and Ag(0)/Ag(I) ratio compared to that obtained using NH3 + NaBH4/glucose methods. The effects of the dosage of chitosan on silver loading, Ag(I) release, and bactericidal activities of AgNP-impregnated silica were investigated, with results showing that, at high dosages of chitosan, Ag(I) released from AgNP-impregnated silica plays an important role in disinfection, while AgNP-mediated bactericidal action dominates at low dosages of chitosan. To further decrease the manufacturing cost, partially oxidized "black rice husk ash" containing substantial residual carbon was applied as AgNP support and found to lead to a greater degree of silver impregnation and to exhibit a longer disinfection lifetime than that of lower carbon content silica supports. On the basis of these findings, it is clear that considerable scope exists for careful optimization in the design and production of AgNP-based bactericidal materials for water treatment purposes. PMID:25272282

  10. A comparative study of elemental additives (Ni, Co and Ag) on electrocatalytic activity improvement of PdSn-based catalysts for ethanol and formic acid electro-oxidation

    International Nuclear Information System (INIS)

    In this study, we have synthesized a series of carbon supported PdSn(molar ratio 1:1), PdSnAg(2:2:1), PdSnNi(2:2:1) and PdSnCo(2:2:1) catalysts by a borohydride reduction method. These catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and chronoamperometry (CA). As compared with PdSn/C, the trimetallic catalysts show a significant activity enhancement for ethanol and formic acid electro-oxidation. Moreover, the PdSnAg/C catalyst exhibits the highest activity together with much better stability. The activity enhancement of PdSnAg/C can be rationalized by the synergistic effect of Pd-SnO2-Ag clusters on the superficial surface of catalyst, such as bi-functional mechanism, superior electronic structure, excellent electric conductivity, etc. In addition, both ethanol and formic acid electro-oxidation reactions on the PdSnAg/C catalyst are diffusion-controlled and represent good linear correlation with ethanol and formic acid concentrations

  11. Synthesis of platinum and platinum–ruthenium-modified diamond nanoparticles

    International Nuclear Information System (INIS)

    With the aim of developing dimensionally stable-supported catalysts for direct methanol fuel cell application, Pt and Pt–Ru catalyst nanoparticles were deposited onto undoped and boron-doped diamond nanoparticles (BDDNPs) through a chemical reduction route using sodium borohydride as a reducing agent. As-received commercial diamond nanoparticles (DNPs) were purified by refluxing in aqueous nitric acid solution. Prompt gamma neutron activation analysis and transmission electron microscopy (TEM) techniques were employed to characterize the as-received and purified DNPs. The purified diamond nanoparticulates, as well as the supported Pt and Pt–Ru catalyst systems, were subjected to various physicochemical characterizations, such as scanning electron microscopy, energy dispersive analysis, TEM, X-ray diffraction, inductively coupled plasma-mass spectrometry, X-ray photoelectron spectroscopy, and infrared spectroscopy. Physicochemical characterization showed that the sizes of Pt and Pt–Ru particles were only a few nanometers (2–5 nm), and they were homogeneously dispersed on the diamond surface (5–10 nm). The chemical reduction method offers a simple route to prepare the well-dispersed Pt and Pt–Ru catalyst nanoparticulates on undoped and BDDNPs for their possible employment as an advanced electrode material in direct methanol fuel cells.

  12. Synthesis of the d,I-HM-PAO and formulation of nucleo-equipment for the obtention of {sup 99m} Tc-(d,I)-HM-PAO; Sintesis del d,I-HM-PAO y formulacion de nucleo-equipos para la obtencion de {sup 99m} Tc-(d,I)-HM-PAO

    Energy Technology Data Exchange (ETDEWEB)

    Lezama C, J.; Ferro F, G.; Alcazar A, P

    1991-09-15

    Most brain imaging radiopharmaceuticals are conventional hydrophilic compounds that are excluded from entering the normal brain by an intact blood-brain barrier (BBB). Under pathologic conditions, the barrier is disrupted and radiotracer concentrates in the leisure for positive identification. {sup 99m} Tc- hexa methyl propylene amine oxime ({sup 99} {sup m} Tc-HM-PAO) is a newer-type lipophilic agent that enter the normal brain through an intact BBB. Studies with this agent offer the promise of measuring cerebral perfusion in the normal and diseased brain. In this paper we present the synthesis and Tc-99m labelling of d,I-HM-PAO. The synthesis of the ligand was carried out by condensation of two molecular equivalents of butanedione monoxime with one molecular equivalent of 1,3 propanediamine provided a bis imine intermediate, which was reduced with sodium borohydride to get the meso and d,I diastereoisomers of HM-PAO. Separation of these was achieved by fractional crystallization. {sup 99m} Tc-(d,I)HM-PAO was obtained by stannous ion reduction of Mo-99/Tc-99m generator eluate in the presence of the ligand. Complex radiochemical purity was determined by instant thin layer chromatography and paper chromatography. Finally, we obtained {sup 99m} Tc-(d,I)HM-PAO with a high radiochemical yield, in excess of 90%. However, for subsequent clinical studies the preparation has to be done a few minutes before application because our product has a low stability. (Author)

  13. Shape tailored green synthesis and catalytic properties of gold nanocrystals

    Science.gov (United States)

    Rajan, Anish; MeenaKumari, M.; Philip, Daizy

    2014-01-01

    The use of environmentally benign procedures is highly desirable for the synthesis of nanoparticles. Here we report a simple, versatile, economic, ecofriendly and reproducible green method for the size-tunable synthesis of stable and crystalline gold nanoparticles of varied shape using aqueous extract of Garcinia Combogia fruit. The predominant anisotropic nature in the morphology of synthesized particles at lower quantities of extract gradually shifted to spherical particles with larger quantity of extract and increase of temperature. The onset of reduction, the time-evolution of the Surface Plasmon Resonance (SPR) and the catalytic activity are studied using UV-Visible spectroscopy. The Selected Area Diffraction (SAED) pattern, the lattice fringes in the High Resolution Transmission Electron Microscopic (HRTEM) image and the X-ray Diffraction (XRD) pattern clearly show the pure crystalline nature of the synthesized gold nanoparticles. The role of carboxyl group present in Garcinia Combogia fruit extract in the reduction of chloroaurate ions is established using Fourier Transform Infrared (FTIR) spectra. The size dependent catalytic activity of the green synthesized gold nanoparticles on the reduction of 4-Nitrophenol to 4-Aminophenol using sodium borohydride is studied and reported for the first time. The first order kinetics is fitted and rate constants are calculated. Catalytically active green synthesized gold nanoparticles with controllable size and shape presents an advanced step in future biomedical and chemical applications.

  14. Controllable Synthesis and Tunable Photocatalytic Properties of Ti(3+)-doped TiO2.

    Science.gov (United States)

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti(3+)-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti(4+) on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti(3+)-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  15. Controllable Synthesis and Tunable Photocatalytic Properties of Ti3+-doped TiO2

    Science.gov (United States)

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti3+-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti4+ on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti3+-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  16. Colorimetric kinetic determination of potassium ions based on the use of a specific aptamer and catalytically active gold nanoparticles

    International Nuclear Information System (INIS)

    We describe a simple, highly sensitive, and selective colorimetric kinetic assay for the determination of potassium(I) by exploiting the specific recognition capability of an appropriate aptamer and catalytic signal amplification by gold nanoparticles (AuNPs). Amplification is based on the reduction of 4-nitrophenol by borohydride which is catalyzed by AuNPs. This leads to a color change of the solution from yellow to colorless, and the color change can be recognized with bare eyes or via photometry. The K(I)-selective aptamer is placed on the AuNPs and forms a tightly bound G-quadruplex with K(I) which partially masks the surface of the AuNPs and prevents 4-nitrophenol to be reduced at the catalytically active surface of the AuNPs. Hence, the rate of decoloration is retarded. The assay displays high selectivity for K(I) over other cations, has a linear response in the 0.1 nM to 10 μM concentration range, and a detection limit as low as 0.06 nM. In addition, these findings pave the way to novel analytical methods based on the use of gold nanoparticle-catalyzed chemical reactions. (author)

  17. Catalytic reductive dechlorination of p-chlorophenol in water using Ni/Fe nanoscale particles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-hua; QUAN Xie; ZHANG Zhuo-yong

    2007-01-01

    Nanoscale bimetallic Ni/Fe particles were synthesized from the reaction of sodium borohydride (NaBH4)with reduction of Ni2+and Fe2+ in aqueous solution.The obtained Ni/Fe particles were characterized by TEM(transmission electron microscope),XRD(X-ray diffractometer),and N2-BET The dechlorination activity of the Ni/Fe was investigated using P-chlorophenol (p-CP)as a pmbe agent.Results demonstrated that the nanoscale Ni/Fe could effectively dechlorinate P-CP at relatively low metal to solution ratio of 0.4 g/L (Ni 5 wt%).The target with initial concentration of P-CP O.625 mmol/L was dechlorinted completely in 60 min under ambient temperature and pressure.Factors affecting dechlorination efficiency,including reaction temperature,pH,Ni loading percentage over Fe,and metal to solution ratio.were investigated.The possible mechanism of dechlorination of P-CP was proposed and discussed.The pseudo-first-order reaction took place on the surface of the Ni/Fe bimetallic particles,and the activation energy of the dechlorination reaction was determined to be 21.2 kJ/mol at the temperature rang of 287-313 K.

  18. A Comparative Study of the Adsorption of Methylene Blue onto Synthesized Nanoscale Zero-Valent Iron-Bamboo and Manganese-Bamboo Composites

    Directory of Open Access Journals (Sweden)

    Solomon E. Shaibu

    2014-06-01

    Full Text Available In this study, bamboo impregnated with nanoscale zero-valent iron (nZVI and nanoscale manganese (nMn were prepared by the aqueous phase borohydride reduction method and characterized using scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR and PIXE analysis. The synthesized nMn-bamboo and nZVI-bamboo composites were subsequently applied to the sorption of methylene blue (MB dye from aqueous solution. The adsorption of MB dye was investigated under various experimental conditions such as pH, contact time, initial concentration of MB dye and adsorbent dosage. The results showed that the synthesized nZVI-bamboo composite was more effective than nMn-bamboo composite in terms of higher MB dye adsorption capacity of 322.5 mg/g compared to 263.5 mg/g of nMn-bamboo composite. At a concentration of 140 mg/L MB dye, 0.02 g of nZVI-bamboo and nMn-bamboo composites resulted in 79.6% and 78.3% removal, respectively, at 165 rpm, contact time of 120 min and at a solution pH of 7.6. The equilibrium data was best represented by Freundlich isotherm model and the pseudo-second order kinetic model better explained the kinetic data for both nZVI-bamboo and nMn-bamboo composites.

  19. Tin Content Determination in Canned Fruits and Vegetables by Hydride Generation Inductively Coupled Plasma Optical Emission Spectrometry

    Directory of Open Access Journals (Sweden)

    Sanda Rončević

    2012-01-01

    Full Text Available Tin content in samples of canned fruits and vegetables was determined by hydride generation inductively coupled plasma atomic emission spectrometry (HG-ICP-OES, and it was compared with results obtained by standard method of flame atomic absorption spectrometry (AAS. Selected tin emission lines intensity was measured in prepared samples after addition of tartaric acid and followed by hydride generation with sodium borohydride solution. The most favorable line at 189.991 nm showed the best detection limit (1.9 μg L−1 and limit of quantification (6.4 μg kg−1. Good linearity and sensitivity were established from time resolved analysis and calibration tests. Analytical accuracy of 98–102% was obtained by recovery study of spiked samples. Method of standard addition was applied for tin determination in samples from fully protected tinplate. Tin presence at low-concentration range was successfully determined. It was shown that tenth times less concentrations of Sn were present in protected cans than in nonprotected or partially protected tinplate.

  20. 苯叉丙酮缩胺化合物及其配合物的合成与表征%Synthesis and Characterization Study of Benzylidene Acetone Condensation Amine and Coordination Complexes

    Institute of Scientific and Technical Information of China (English)

    李章; 李淼; 李洪东; 戚峰; 滕云霞; 周徐亮; 王寿武

    2014-01-01

    利用乙二胺和亚苄基丙酮反应合成了不饱和化合物(Ph2Me2[14]dieneN4),再用硼氢化钾与不饱和化合物还原生成饱和的十四元大环化合物(Ph2Me2[14]H2dieneN4),并用盐酸和氢氧化钠对饱和十四元大环进行提纯,得到纯的十四元大环希夫碱并与乙酸酮反应生成配合物,通过红外光谱进行了表征。%The unsaturated Ph2Me2[14]dieneN4( Ⅱ ) compound was formed by ethylene diamine and benzylidene ketones reaction, then the unsaturated Ph2Me2[14]dieneN4( Ⅱ ) was reduced to the saturated fourteen macrocyclic compound Ph2Me2[14] H2dienenN4( Ⅲ ) by potassium borohydride. The saturated fourteen macrocyclic compound was purified with hydrochloric acid and sodium hydroxide. The copper complex was synthesized by this fourteen macrocyclic compound and copper acetate. The title complex was characterized by infrared spectroscopy.

  1. Importance of the terminal α-amino group of bradykinin and some kynins on capillary permeability increase

    International Nuclear Information System (INIS)

    A simple and reliable method is described for the quantitative evaluation of vascular permeability increase induced by vasoactive drugs with Evans blue labelled with iodine-125 or 131. By using this method the importance of α-amino group of bradykinin (Bk), kallidin (Kd) and methionyl-kallidin (Met-Kd) on the biological activity were studied after reacting the kinins with pyridoxal 5'-phosphate followed by reduction with sodium borohydride. Phosphopyridoxyl-kinins were formed leaving free the guanidino groups. Aminoacid analysis of phosphopyridoxyl-kinin showed that the efficiency of the reaction was extremely good in the blockage of α-amino groups [phosphopyridoxyl-bradikinin (PP-Bk) = 98,8%, phosphopyridoxyl-kallidin (PP-Kd) = 95,2%, phosphopyridoxyl-methionyl-kallidin (PP-Met-Kd) = 98,0%. Log dose-response curves were obtained for Bk, Kd, Met-Kd, acetyl-bradykinin (Ac-Bk), PP-Bk, PP-Kd and PP-Met-Kd and the relative potencies calculated through the Lineweaver-Burk plots. The relative potencies were: PP-Bk about 16% the activity of Bk, Ac-Bk about 31% the activity of Bk, PP-Kd about 17% the activity of Kd, PP-Met-Kd about 12% the activity of Met-Kd. The results show that the terminal α-amino group of kinins is important in the mechanisms of biological activity. (Author)

  2. Improved process for the synthesis of [2,2]-paracyclophane

    Science.gov (United States)

    Zhang, Long; Wang, Juan; Gao, Leng; Xu, Yulun; Gao, Weimin

    2006-01-01

    An improved method for the preparation of [2,2]-paracyclophane, which is the monomer of poly-p-xylene widely used as high quality electrical coating material, by Hoffmann elimination employing p-methyl-benzyl chloride and trimethyl amine as main raw materials was developed. Influence of solvent, reaction time, reaction temperature etal on the yield of paracyclophane was investigated experimentally. Suitable reaction parameters were obtained as follows: n(Alkali) : n(Quaternary ammonium) is 5:1; catalyst: 0.2% cupric salt; with 1,4-dioxane as solvent and 0.2% sodium borohydride as reducer, and N II as protection gas; reaction temperature 110°C, reaction time is 30 hr, at the condition, the yield of [2,2]-paracyclophane is 78.6%, its purity is over 99.5%, with melting point 284-285°C. Analysis results by IR and melting temperature measurement etal identify the substance synthesized is [2,2]-paracyclophane. And the materials used is industrially available and better yield was obtained comparing with the values present in the patent literatures.

  3. Cerebral biochemical abnormalities in experimental maternal phenylketonuria: gangliosides and sialoglycoproteins

    International Nuclear Information System (INIS)

    The present study sought a biochemical explanation for retarded brain development in the heterozygous offspring of the phenylketonuric (PKU) mother. Two rat models of simulated maternal PKU, one induced by p-chloropheylalanine and phenylalanine and the other by phenylacetate, were employed in this investigation. Maternal PKU had no influence on cerebral concentrations of DNA, protein, and cholesterol, which were normal in the 2 d old pup. However, there was a noticeable disruption of the normal ganglioside pattern and a significant reduction of sialoglycoproteins. Concomitant with a delayed drop in the gangliosides Q/sub 1b/ and D3, was a slower rise in M1 and D/sub 1a/. At least 66% of sialoglycoproteins located on SDS-PAGE gel chromatograms, by radioactivity incorporated in vivo from radiolabeled N-acetylmannosamine and by (3H) sialic acid released by neuraminidase from periodate-(3H) borohydride labeled glycoproteins, have mobilites of the cell adhesion molecules N-CAM and D-CAM. Whether the reduction of the sialogylcoproteins induced by maternal PKU is mainly in these cell adhesion molecules requires further investigation. Interference with the function of gangliosides and certain sialoglycoproteins during cerebral development may contribute to the brain dysfunction observed in the offspring of PKU mothers not on diet control during pregnancy. 49 references, 2 figures, 3 tables

  4. Synthesis and Crystal Structure of(3S,4R,Z)-3,6-dimethyl-2-(3-methylbut-2-enylidene)-2,3,3a,4,7,7a-hexahydrobenzofuran-3,4-diol

    Institute of Scientific and Technical Information of China (English)

    CHEN Lei; FANG Hu-Biao; HUANG Nian-Yu; WANG Jun-Zhi; ZOU Kun

    2011-01-01

    The title compound of(3S,4R,Z)-3,6-dimethyl-2-(3-methylbut-2-enylidene)-2,3,3a,4,7,7a-hexahydrobenzofuran-3,4-diol,C15H22O3,as a potential gastric cytoprotective agent has been synthesized by the reduction of bisabolangelone in methanol with sodium borohydride.The title compound was characterized by IR and NMR spectra.Meanwhile,the crystal was obtained and determined by X-ray single-crystal diffraction.Crystal data:monoclinic system,space group P21 with a = 6.0692(12),b = 8.9954(18),c = 13.182(3) ,β = 92.59(3)°,V = 718.9(2) 3,Z = 2,F(000) = 272,Dc = 1.156 g/cm3,μ = 0.633 mm-1,R = 0.0362 and wR = 0.1051 for 9490 independent reflections(Rint = 0.0172) and 2461 observed reflections(I 2σ(I)).Intermolecular O-H…O interactions link the molecules into one-dimensional infinite chains running along the b axis,which contributes to the stability of the crystal structure.

  5. An overview of preparation and applications of stabilized zero-valent iron nanoparticles for soil and groundwater remediation.

    Science.gov (United States)

    Zhao, Xiao; Liu, Wen; Cai, Zhengqing; Han, Bing; Qian, Tianwei; Zhao, Dongye

    2016-09-01

    Nano-scale zero-valent iron (nZVI) is one of the most intensively studied materials for environmental cleanup uses over the past 20 years or so. Freshly prepared nZVI is highly reactive due to its high specific surface area and strong reducing power. Over years, the classic borohydride reduction method for preparing nZVI has been modified by use of various stabilizers or surface modifiers to acquire more stable and soil deliverable nZVI for treatment of different organic and inorganic contaminants in water and soil. While most studies have been focused on testing nZVI for water treatment, the greater potential or advantage of nZVI appears to be for in situ remediation of contaminated soil and groundwater by directly delivering stabilized nZVI into the contaminated subsurface as it was proposed from the beginning. Compared to conventional remediation practices, the in situ remediation technique using stabilized nZVI offers some unique advantages. This work provides an update on the latest development of stabilized nZVI for various environmental cleanup uses, and overviews the evolution and environmental applications of stabilized nZVI. Commonly used stabilizers are compared and the stabilizing mechanisms are discussed. The effectiveness and constraints of the nZVI-based in situ remediation technology are summarized. This review also reveals some critical knowledge gaps and research needs, such as interactions between delivered nZVI and the local biogeochemical conditions. PMID:27206054

  6. The impact of kappa number composition on eucalyptus kraft pulp bleachability

    Directory of Open Access Journals (Sweden)

    M. M. Costa

    2007-03-01

    Full Text Available Consumption of chemicals during ECF bleaching of kraft pulp correlates reasonably well with kappa number, which measures with KMnO4 the total amount of oxidizable material in the pulp. However, the method does not distinguish between the oxidizable material in residual lignin and other structures susceptible to oxidation, such as hexenuronic acids (HexAs, extractives and carbonyl groups in the pulp. In this study an attempt is made to separate the main contributors to the kappa number in oxygen - delignified eucalyptus Kraft pulps and evaluate how these fractions behave during ECF bleaching using chlorine dioxide as the sole oxidant (DEDD sequence. Residual lignin and HexAs proved to be the main fractions contributing to the kappa number and chlorine dioxide consumption in ECF bleaching. Pulp bleachability with chlorine dioxide increases with increasing HexAs content of the pulp but chlorine dioxide per se does not react with HexAs. Reduction of pulp with sodium borohydride under conditions for removing carbonyl groups has no impact on bleachability. No correlation was found between the pulp of the extractive content and pulp bleachability. The removal of HexAs prior to ECF bleaching significantly decreases the formation of chlorinated organics in the pulp (OX and filtrates (AOX as well as of oxalic acids in the filtrates.

  7. Micro reactor integrated μ-PEM fuel cell system: a feed connector and flow field free approach

    International Nuclear Information System (INIS)

    A system level microreactor concept for hydrogen generation with Sodium Borohydride (NaBH4) is demonstrated. The uniqueness of the system is the transport and distribution feature of fuel (hydrogen) to the anode of the fuel cell without any external feed connectors and flow fields. The approach here is to use palladium film instead of feed connectors and the flow fields; palladium's property to adsorb and desorb the hydrogen at ambient and elevated condition. The proof of concept is demonstrated with a polymethyl methacrylate (PMMA) based complete system integration which includes microreactor, palladium transport layer and the self-breathing polymer electrolyte membrane (PEM) fuel cell. The hydrolysis of NaBH4 was carried out in the presence of platinum supported by nickel (NiPt). The prototype functionality is tested with NaBH4 chemical hydride. The characterization of the integrated palladium layer and fuel cell is tested with constant and switching load. The presented integrated fuel cell is observed to have a maximum power output and current of 60 mW and 280 mA respectively

  8. Growth of fluorescence gold clusters using photo-chemically activated ligands

    Science.gov (United States)

    Mishra, Dinesh; Aldeek, Fadi; Michael, Serge; Palui, Goutam; Mattoussi, Hedi

    2016-03-01

    Ligands made of lipoic acid (LA) appended with a polyethylene glycol (PEG) chain have been used in the aqueous phase growth of luminescent gold clusters with distinct emission from yellow to near-IR, using two different routes. In the first route, the gold-ligand complex was chemically reduced using sodium borohydride in alkaline medium, which gave near- IR luminescent gold clusters with maximum emission around 745 nm. In the second method, LA-PEG ligand was photochemically modified to a mixture of thiols, oligomers and oxygenated species under UV-irradiation, which was then used as both reducing agent and stabilizing ligand. By adjusting the pH, temperature, and time of the reaction, we were able to obtain clusters with two distinct emission properties. Refluxing the gold-ligand complex in alkaline medium in the presence of excess ligand gave yellow emission within the first two hours and the emission shifted to red after overnight reaction. Mass spectrometry and chemical assay were used to understand the photo-chemical transformation of Lipoic Acid (LA). Mass spectroscopic studies showed the photo-irradiated product contains thiols, oligomers (dimers, trimers and tetramers) as well as oxygenated species. The amount of thiol formed under different conditions of irradiation was estimated using Ellman's assay.

  9. Thematic outlook: the technical survey for the fuel cell research network PACO. February 26, 2004 update no. 21; Veille thematique. La veille technique pour le reseau PACO. Actualisation du 26 fevrier 2004, no. 21

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    Summaries of several recent articles are gathered here. They deal with fuel cells, means of transport, hydrogen production and storage, environment. Their different titles are given below: 1)a 10 kW pressurized SOFC unit 2)design of a SOFC system for unstable network 3)demonstration for the general public of high and low temperature fuel cells 4)development of an APU for mobile application based on the SOFC technology 5)fuel cells as continuous supply source 6)PEM fuel cells with carbon nano-tubes electrodes 7)a temperature control system of a reformer fed by a fuel cell 8)the hybridization, a solution for fuel cell vehicles 9)hydrogen production by ethanol auto-thermal reforming on a Rh/Al{sub 2}O{sub 3} catalyst 10)partial oxidation reforming catalyst for fuel cells vehicles 11)hydrogen production increased by a reactive mixture of alkaline aqueous solutions of an alkaline metal borohydride for fuel cells 12)development of an hydrogen generator (of about 10 kW) using chemical hydrides 13)device for pure gases production, in particular hydrogen and oxygen, from gaseous or liquid mixtures, for stationary and mobile applications 14)hydrogen storage in carbon nano-tubes synthesized by pyrolysis with a nickel-lanthanum catalyst 15)estimation of the new energetic and transport systems; the case of fuel cells, part 2: environmental performances. The references of these articles are detailed. (O.M.)

  10. Fabrication of Au nanoparticles supported on CoFe2O4 nanotubes by polyaniline assisted self-assembly strategy and their magnetically recoverable catalytic properties

    Science.gov (United States)

    Zhang, Zhen; Jiang, Yanzhou; Chi, Maoqiang; Yang, Zezhou; Nie, Guangdi; Lu, Xiaofeng; Wang, Ce

    2016-02-01

    This article reports the fabrication of magnetically responsive Au nanoparticles supported on CoFe2O4 nanotubes through polyaniline (PANI) assisted self-assembly strategy which can be used as an efficient magnetically recoverable nanocatalyst. The central magnetic CoFe2O4 nanotubes possess a strong magnetic response under an externally magnetic field, enabling an easy and efficient separation from the reaction system for reuse. The thorn-like PANI layer on the surface of CoFe2O4 nanotubes provides large surface area for supporting Au nanocatalysts due to the electrostatic interactions. The as-prepared CoFe2O4/PANI/Au nanotube assemblies exhibit a high catalytic activity for the hydrogenation of 4-nitrophenol by sodium borohydride (NaBH4) at room temperature, with an apparent kinetic rate constant (Kapp) of about 7.8 × 10-3 s-1. Furthermore, the composite nanocatalyst shows a good recoverable property during the catalytic process. This work affords a reliable way in developing multifunctional nanocomposite for catalysis and other potential applications in many fields.

  11. Generation of an ordered layer of silver nanoparticles in mesostructured dielectric films

    Energy Technology Data Exchange (ETDEWEB)

    Battie, Yann; Destouches, Nathalie, E-mail: destoucn@univ-st-etienne.f [Universite de Lyon (France); Bois, Laurence; Chassagneux, Fernand [Universite De Lyon, Laboratoire Multimateriaux et Interfaces UMR 5615 CNRS Universite Claude Bernard Lyon 1 (France); Moncoffre, Nathalie; Toulhoat, Nelly [Universite Lyon, IPNL, Universite de Lyon 1, CNRS/IN2P3 (France); Jamon, Damien [Universite de Lyon, Laboratoire DIOM EA 3526, Universite Jean Monnet (France); Ouerdane, Youcef [Universite de Lyon (France); Parola, Stephane [Universite De Lyon, Laboratoire Multimateriaux et Interfaces UMR 5615 CNRS Universite Claude Bernard Lyon 1 (France); Boukenter, Aziz [Universite de Lyon (France)

    2010-03-15

    Mesostructured organic-inorganic silica films containing AgNO{sub 3} are used as template to form ordered and dense layers of silver nanoparticles embedded in a dielectric matrix. The hybrid silica films are mesostructured by a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide ((PEO){sub 106}(PPO){sub 70}(PEO){sub 106}, F127) and contain the silver precursor (AgNO{sub 3}) which is dissolved directly in the silica sol prior to deposition. The films are reacted with a sodium borohydride solution (NaBH{sub 4}), which leads to the formation of a plane ordered network of silver oblate nanoparticles with a narrow size distribution located just below the film surface, and observed by Transmission Electron Microscopy (TEM). The minor and major axis lengths are equal to 5.3 {+-} 0.5 and 7.2 {+-} 0.6 nm, respectively. The characterization of the mesostructured film before and after the reductive treatment evidences that silver particles grow in place of copolymer micelles in the upper layer of the mesostructured thin film. Rutherford Backscattering Spectrometry (RBS) measurements support the hypothesis that silver ions initially dispersed in the film volume migrate toward the film surface to form the monolayer of silver nanoparticles, organized and stabilized by the copolymer micelles in the film. IR and ellipsometric measurements are used to characterize the changes in the hybrid copolymer-silica matrix.

  12. Generation of an ordered layer of silver nanoparticles in mesostructured dielectric films

    International Nuclear Information System (INIS)

    Mesostructured organic-inorganic silica films containing AgNO3 are used as template to form ordered and dense layers of silver nanoparticles embedded in a dielectric matrix. The hybrid silica films are mesostructured by a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide ((PEO)106(PPO)70(PEO)106, F127) and contain the silver precursor (AgNO3) which is dissolved directly in the silica sol prior to deposition. The films are reacted with a sodium borohydride solution (NaBH4), which leads to the formation of a plane ordered network of silver oblate nanoparticles with a narrow size distribution located just below the film surface, and observed by Transmission Electron Microscopy (TEM). The minor and major axis lengths are equal to 5.3 ± 0.5 and 7.2 ± 0.6 nm, respectively. The characterization of the mesostructured film before and after the reductive treatment evidences that silver particles grow in place of copolymer micelles in the upper layer of the mesostructured thin film. Rutherford Backscattering Spectrometry (RBS) measurements support the hypothesis that silver ions initially dispersed in the film volume migrate toward the film surface to form the monolayer of silver nanoparticles, organized and stabilized by the copolymer micelles in the film. IR and ellipsometric measurements are used to characterize the changes in the hybrid copolymer-silica matrix.

  13. The Enhanced Catalytic Activities of Asymmetric Au-Ni Nanoparticle Decorated Halloysite-Based Nanocomposite for the Degradation of Organic Dyes

    Science.gov (United States)

    Jia, Lei; Zhou, Tao; Xu, Jun; Li, Xiaohui; Dong, Kun; Huang, Jiancui; Xu, Zhouqing

    2016-02-01

    Janus particles (JPs) are unique among the nano-/microobjects because they provide asymmetry and can thus impart drastically different chemical or physical properties. In this work, we have fabricated the magnetic halloysite nanotube (HNT)-based HNTs@Fe3O4 nanocomposite (NCs) and then anchored the Janus Au-Ni or isotropic Au nanoparticles (NPs) to the surface of external wall of sulfydryl modified magnetic nanotubes. The characterization by physical methods authenticates the successful fabrication of two different magnetic HNTs@Fe3O4@Au and HNTs@Fe3O4@Au-Ni NCs. The catalytic activity and recyclability of the two NCs have been evaluated considering the degradation of Congo red (CR) and 4-nitrophenol (4-NP) using sodium borohydride as a model reaction. The results reveal that the symmetric Au NPs participated NCs display low activity in the degradation of the above organic dyes. However, a detailed kinetic study demonstrates that the employ of bimetallic Janus Au-Ni NPs in the NCs indicates enhanced catalytic activity, owing to the structurally specific nature. Furthermore, the magnetic functional NCs reported here can be used as recyclable catalyst which can be recovered simply by magnet.

  14. Theoretical study of C{sub 60} as catalyst for dehydrogenation in LiBH{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Scheicher, Ralph H; Araujo, C Moyses; Blomqvist, Andreas; Ahuja, Rajeev [Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Li, Sa; Jena, Puru, E-mail: ralph.scheicher@physics.uu.se [Physics Department, Virginia Commonwealth University, Richmond, VA 23284 (United States)

    2011-08-19

    Complex light metal hydrides possess many properties which make them attractive as a storage medium for hydrogen, but typically catalysts are required to lower the hydrogen desorption temperature and to facilitate hydrogen uptake in the form of a reversible reaction. The overwhelming focus in the search for catalysing agents has been on compounds containing titanium, but the precise mechanism of their actions remains somewhat obscure. A recent experiment has now shown that fullerenes (C{sub 60}) can also act as catalysts for both hydrogen uptake and release in lithium borohydride (LiBH{sub 4}). In an effort to understand the involved mechanism, we have employed density functional theory to carry out a detailed study of the interaction between this complex metal hydride and the carbon nanomaterial. Considering a stepwise reduction of the hydrogen content in LiBH{sub 4}, we find that the presence of C{sub 60} can lead to a substantial reduction of the involved H-removal energies. This effect is explained as a consequence of the interaction between the BH{sub x}{sup -} complex and the C{sub 60} entity.

  15. Facile synthesis of near-monodisperse Ag-Ni core-shell nanoparticles and their application for catalytic generation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Guo Huizhang; Chen Yuanzhi; Chen Xiaozhen; Wen Ruitao; Yue Guanghui; Peng Dongliang, E-mail: yuanzhi@xmu.edu.cn, E-mail: dlpeng@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)

    2011-05-13

    Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 {+-} 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H{sub 2} from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.

  16. Fabrication and characterisation of gold nano-particle modified polymer monoliths for flow-through catalytic reactions and their application in the reduction of hexacyanoferrate

    International Nuclear Information System (INIS)

    Polymer monoliths in capillary (100 μm i.d.) and polypropylene pipette tip formats (vol: 20 μL) were modified with gold nano-particles (AuNP) and subsequently used for flow-through catalytic reactions. Specifically, methacrylate monoliths were modified with amine-reactive monomers using a two-step photografting method and then reacted with ethylenediamine to provide amine attachment sites for the subsequent immobilisation of 4 nm, 7 nm or 16 nm AuNP. This was achieved by flushing colloidal suspensions of gold nano-particles through each aminated polymer monolith which resulted in a multi-point covalent attachment of gold via the lone pair of electrons on the nitrogen of the free amine groups. Field emission scanning electron microscopy and scanning capacitively coupled conductivity detection was used to characterise the surface coverage of AuNP on the monoliths. The catalytic activity of AuNP immobilised on the polymer monoliths in both formats was then demonstrated using the reduction of Fe(III) to Fe(II) by sodium borohydride as a model reaction by monitoring the reduction in absorbance of the hexacyanoferrate (III) complex at 420 nm. Catalytic activity was significantly enhanced on monoliths modified with smaller AuNP with almost complete reduction (95 %) observed when using monoliths agglomerated with 7 nm AuNPs. (author)

  17. Biogenic robust synthesis of silver nanoparticles using Punica granatum peel and its application as a green catalyst for the reduction of an anthropogenic pollutant 4-nitrophenol

    Science.gov (United States)

    Edison, T. Jebakumar Immanuel; Sethuraman, M. G.

    2013-03-01

    A robust synthesis of silver nanoparticles (AgNPs) using the peel extract of Punica granatum is reported in this article. The formation of AgNPs was confirmed by the appearance of brownish yellow color and the Surface Plasmon Resonance (SPR) peak at 432 nm. The biogenic AgNPs were found to have the size approximately 30 nm with distorted spherical shape. The high negative zeta potential values of AgNPs revealed their high stability which could be attributed to the capping of AgNPs by the phytoconstituents of the Punica granatum peel. The biogenic AgNPs were also found to function as an effective green catalyst in the reduction of anthropogenic pollutant viz., 4-nitrophenol (4-NP) by solid sodium borohydride, which was evident from the instantaneous color change of bright yellow (400 nm) to colorless (294 nm) solution, after the addition of AgNPs. The catalytic action of biogenic AgNPs in the reduction of 4-NP could be explained on the basis of Langmuir-Hinshelwood model.

  18. Antibacterial continuous nanofibrous hybrid yarn through in situ synthesis of silver nanoparticles: Preparation and characterization

    International Nuclear Information System (INIS)

    Nanofibrous hybrid yarns of polyvinyl alcohol (PVA) and poly-L-lactide acid (PLLA) with the antibacterial activity were prepared that contains 0, 5, 10, 20, and 30 wt.% of silver nanoparticles according to the PVA polymer content. This was performed by electrospinning using distilled water and 2, 2, 2-trifluoroethanol as a solvent for PVA and PLLA respectively, and sodium borohydride was used as a reducing agent. The scanning electron microscope observation confirmed the formation of AgNPs into the PVA nanofiber structure, and they were uniform, bead free, cylindrical and smooth. The diameter of hybrid yarns and their nanofiber component was decreased as the silver nitrate concentration in electrospinning solutions was increased. The differential scanning calorimetry results indicated that the silver nanoparticles can form interactions with polymer chains and decrease the melting enthalpy. The mechanical analysis showed a lower stress and strain at break of the AgNP-loaded nanofibrous hybrid yarns than the unloaded hybrid yarn. However, there wasn't a statistically significant difference between the strain at break of electrospun nanofibrous hybrid yarns. Moreover, the bactericidal efficiency of all loaded samples was over 99.99%. - Highlights: • Nanofibrous hybrid yarns of PVA/PLLA with antibacterial activity were prepared. • The diameter of nanofibers was decreased as the AgNP concentration was increased. • AgNPs make interactions with amorphous phase of polymer and increase the Tg. • All loaded samples presented a good bactericidal and bacteriostatic efficiency

  19. Colorimetric detection of Bi (III) in water and drug samples using pyridine-2,6-dicarboxylic acid modified silver nanoparticles

    Science.gov (United States)

    Mohammadi, Somayeh; Khayatian, Gholamreza

    2015-09-01

    A new selective, simple, fast and sensitive method is developed for sensing assay of Bi (III) using pyridine-2,6-dicarboxylic acid or dipicolinic acid (DPA) modified silver nanoparticles (DPA-AgNPs). Silver nanoparticles (AgNPs) were synthesized by reducing silver nitrate (AgNO3) with sodium borohydride (NaBH4) in the presence of DPA. Bismuth detection is based on color change of nanoparticle solution from yellow to red that is induced in the presence of Bi (III). Aggregation of DPA-AgNPs has been confirmed with UV-vis absorption spectra and transmission electron microscopy (TEM) images. Under the optimized conditions, a good linear relationship (correlation coefficient r = 0.995) is obtained between the absorbance ratio (A525/A390) and the concentration of Bi (III) in the 0.40-8.00 μM range. This colorimetric probe allows Bi (III) to be rapidly quantified with a 0.01 μM limit of detection. The present method successfully applied to determine bismuth in real water and drug samples. Recoveries of water samples were in the range of 91.2-99.6%.

  20. Colorimetric humidity sensor based on liquid composite materials for the monitoring of food and pharmaceuticals.

    Science.gov (United States)

    Bridgeman, Devon; Corral, Javier; Quach, Ashley; Xian, Xiaojun; Forzani, Erica

    2014-09-01

    Using supported ionic-liquid membrane (SILM)-inspired methodologies, we have synthesized, characterized, and developed a humidity sensor by coating a liquid composite material onto a hygroscopic, porous substrate. Similar to pH paper, the sensor responds to the environment's relative humidity and changes color accordingly. The humidity indicator is prepared by casting a few microliters of low-toxicity reagents on a nontoxic substrate. The sensing material is a newly synthesized liquid composite that comprises a hygroscopic medium for environmental humidity capture and a color indicator that translates the humidity level into a distinct color change. Sodium borohydride was used to form a liquid composite medium, and DenimBlu30 dye was used as a redox indicator. The liquid composite medium provides a hygroscopic response to the relative humidity, and DenimBlu30 translates the chemical changes into a visual change from yellow to blue. The borate-redox dye-based humidity sensor was prepared, and then Fourier transform infrared spectroscopy, differential scanning calorimetry, and image analysis methods were used to characterize the chemical composition, optimize synthesis, and gain insight into the sensor reactivity. Test results indicated that this new sensing material can detect relative humidity in the range of 5-100% in an irreversible manner with good reproducibility and high accuracy. The sensor is a low-cost, highly sensitive, easy-to-use humidity indicator. More importantly, it can be easily packaged with products to monitor humidity levels in pharmaceutical and food packaging. PMID:25141132

  1. Purification and characterization of a novel UV lesion-specific DNA glycosylase/AP lyase from Bacillus sphaericus.

    Science.gov (United States)

    Vasquez, D A; Nyaga, S G; Lloyd, R S

    2000-05-31

    The purification and characterization of a pyrimidine dimer-specific glycosylase/AP lyase from Bacillus sphaericus (Bsp-pdg) are reported. Bsp-pdg is highly specific for DNA containing the cis-syn cyclobutane pyrimidine dimer, displaying no detectable activity on oligonucleotides with trans-syn I, trans-syn II, (6-4), or Dewar photoproducts. Like other glycosylase/AP lyases that sequentially cleave the N--glycosyl bond of the 5' pyrimidine of a cyclobutane pyrimidine dimer, and the phosphodiester backbone, this enzyme appears to utilize a primary amine as the attacking nucleophile. The formation of a covalent enzyme-DNA imino intermediate is evidenced by the ability to trap this protein-DNA complex by reduction with sodium borohydride. Also consistent with its AP lyase activity, Bsp-pdg was shown to incise an AP site-containing oligonucleotide, yielding beta- and delta-elimination products. N-terminal amino acid sequence analysis of this 26 kDa protein revealed little amino acid homology to any previously reported protein. This is the first report of a glycosylase/AP lyase enzyme from Bacillus sphaericus that is specific for cis-syn pyrimidine dimers. PMID:10844244

  2. Biosynthesis of gold nanoparticles and related cytotoxicity evaluation using A549 cells.

    Science.gov (United States)

    Sathishkumar, M; Pavagadhi, S; Mahadevan, A; Balasubramanian, R

    2015-04-01

    Biosynthesis of gold nanoparticles (AuNPs) has become an attractive area of research as it is environmentally benign. The toxicity of AuNPs synthesized by chemical routes has been widely studied. However, little is known about the toxicity associated with the biological synthesis of AuNPs. The present study was carried out to synthesize AuNPs using star anise (Illicium verum; a commercially available spice in abundance)and evaluate its toxicity using human epithelial lung cells (A549) in comparison with AuNPs synthesized by the traditional chemical methods (using sodium citrate and sodium borohydride). Apart from cell viability, markers of oxidative stress (reduced glutathione) and cell death (caspases) were also evaluated to understand the mechanisms of toxicity. Cell viability was observed to be 65.7 percent and 72.3 percent in cells exposed to chemically synthesized AuNPs at the highest dose (200nM) as compared to 80.2 percent for biologically synthesized AuNPs. Protective coating/capping of AuNPs by various polyphenolic compounds present in star anise extract appears to be a major contributor to lower toxicity observed in biologically synthesized AuNPs. PMID:24835429

  3. Comparison of characteristics of montmorillonite supported nano zero valent iron (M-nZVI) and nano zero valent iron (nZVI)

    Science.gov (United States)

    How, Ho Kuok; Wan Zuhairi W., Y.

    2015-09-01

    In this study, synthesized montmorillonite supported nano zero valent iron (M-nZVI) and nano zero valent iron (nZVI) are compared physically and chemically. The samples were prepared using chemical reduction method that includes sodium borohydride and ethanol. Due to the tendency of nZVI to aggregate, montmorillonite is used as a supporting material. TEM and FESEM images show that the M-nZVI has decreased the aggregation by dispersing the particles on the surface of montmorillonite whereas images of nZVI show chain-like particle due to aggregation. Both images also show particles synthesized are nanoparticles. With less aggregation, the surface area of the M-nZVI is greater than nZVI which is 45.46 m2/g and 10.49 m2/g respectively. XRD patterns have shown Fe0 are synthesized and small amount of iron oxides are produced. M-nZVI has the capability in reducing aggregation which might lead to the increase in reactivity of the particles thus enhancing the performance of nZVI.

  4. Interleaved mesoporous copper for the anode catalysis in direct ammonium borane fuel cells.

    Science.gov (United States)

    Auxilia, Francis M; Tanabe, Toyokazu; Ishihara, Shinsuke; Saravanan, Govindachetty; Ramesh, Gubbala V; Matsumoto, Futoshi; Ya, Xu; Ariga, Katsuhiko; Dakshanamoorthy, Arivuoli; Abe, Hideki

    2014-06-01

    Mesoporous materials with tailored microstructures are of increasing importance in practical applications particularly for energy generation and/or storage. Here we report a mesoporous copper material (MS-Cu) can be prepared in a hierarchical microstructure and exhibit high catalytic performance for the half-cell reaction of direct ammonium borane (NH3BH3) fuel cells (DABFs). Hierarchical copper oxide (CuO) nanoplates (CuO Npls) were first synthesized in a hydrothermal condition. CuO Npls were then reduced at room temperature using water solution of sodium borohydride (NaBH4) to yield the desired mesoporous copper material, MS-Cu, consisting of interleaved nanoplates with a high density of mesopores. The surface of MS-Cu comprised high-index facets, whereas a macroporous copper material (MC-Cu), which was prepared from CuO Npls at elevated temperatures in a hydrogen stream, was surrounded by low-index facets with a low density of active sites. MS-Cu exhibited a lower onset potential and improved durability for the electro-oxidation of NH3BH3 than MC-Cu or copper particles because of the catalytically active mesopores on the interleaved nanoplates. PMID:24738410

  5. Comparison of the reactions induced by ultrasound and gamma rays in aqueous lactose solutions

    Energy Technology Data Exchange (ETDEWEB)

    Heusinger, H. (Technische Univ. Muenchen, Garching (Germany, F.R.). Inst. fuer Radiochemie)

    1990-01-01

    The products obtained in aerated aqueous lactose solutions after irradiation with ultrasound and gamma rays were compared. The dose rate of gamma irradiation equivalent to the effect of ultrasound in our experiments was determined to be 1.384 kGy h{sup -1} using the Fricke dosimeter. Separation and identification of the products were performed by gas chromatography-mass spectrometry. Three methods for the derivation of products were used: trimethylsilylation of the OH-groups; methoximation of the carbonyl groups followed by trimethylsilylation of the OH-groups; and reduction of the carbonyl and carboxyl groups to alcohols by sodium borohydride and sodium borodeuteride. The formation of products for both types of irradiation was identical, showing only minor deviations in the yield. The main reaction was oxidative splitting of the glucosidic bond, resulting in the formation of galactonic acid, glucose and galactose. Hexoculoses, gluconic acid, hexulosonic acids and glucuronic acid were detected as secondary products still containing the intact monosaccharide units. In addition, oxidation products with three to five carbon atoms were observed. The main product still containing 12 carbon atoms was lactobionic acid. (author).

  6. Determination of antimony in environment samples by gas phase chemiluminescence detection following flow injection hydride generation and cryotrapping.

    Science.gov (United States)

    Ye, Yousheng; Sang, Jianchi; Ma, Hongbing; Tao, Guanhong

    2010-06-15

    A novel method for the determination of antimony in environmental samples was developed with gas phase chemiluminescence detection following flow injection hydride generation and cryotrapping. The stibine, generated from samples by borohydride reduction of antimony using flow injection technique, was separated by using a new gas-liquid separator, dried with an ice-salt cryogenic bath and concentrated in a glass U-tube immersed in liquid nitrogen. Re-vaporization of stibine based on its boiling point was achieved by allowing the tube to warm at room temperature. A gas phase chemiluminescence signal was produced during the ozonation of the hydride in a reflective chamber. Under optimal conditions, the proposed method was characterized by a wide linear calibration range from 1.0microgL(-1) to 10.0mgL(-1) with a detection limit of 0.18microgL(-1) (n=11). The relative standard deviation for 10.0microgL(-1) antimony was 3.56% (n=11) and the sampling rate was 15 samples h(-1). Blank signal was reduced by the purification of reagents and the interference from transition metal ions was eliminated by the addition of L-cysteine into samples. The method was applied to the determination of antimony in environmental samples with satisfactory results. PMID:20441930

  7. Complete amino acid sequence of branched-chain amino acid aminotransferase (transaminase B) of Salmonella typhimurium, identification of the coenzyme-binding site and sequence comparison analysis

    International Nuclear Information System (INIS)

    The complete amino acid sequence of the subunit of branched-chain amino acid aminotransferase of Salmonella typhimurium was determined by automated Edman degradation of peptide fragments generated by chemical and enzymatic digestion of S-carboxymethylated and S-pyridylethylated transaminase B. Peptide fragments of transaminase B were generated by treatment of the enzyme with trypsin, Staphylococcus aureus V8 protease, endoproteinase Lys-C, and cyanogen bromide. Protocols were developed for separation of the peptide fragments by reverse-phase high performance liquid chromatography (HPLC), ion-exchange HPLC, and SDS-urea gel electrophoresis. The enzyme subunit contains 308 amino acid residues and has a molecular weight of 33,920 daltons. The coenzyme-binding site was determined by treatment of the enzyme, containing bound pyridoxal 5-phosphate, with tritiated sodium borohydride prior to trypsin digestion. Monitoring radioactivity incorporation and peptide map comparisons with an apoenzyme tryptic digest, allowed identification of the pyridoxylated-peptide which was isolated by reverse-phase HPLC and sequenced. The coenzyme-binding site is a lysyl residue at position 159. Some peptides were further characterized by fast atom bombardment mass spectrometry

  8. The Enhanced Catalytic Activities of Asymmetric Au-Ni Nanoparticle Decorated Halloysite-Based Nanocomposite for the Degradation of Organic Dyes.

    Science.gov (United States)

    Jia, Lei; Zhou, Tao; Xu, Jun; Li, Xiaohui; Dong, Kun; Huang, Jiancui; Xu, Zhouqing

    2016-12-01

    Janus particles (JPs) are unique among the nano-/microobjects because they provide asymmetry and can thus impart drastically different chemical or physical properties. In this work, we have fabricated the magnetic halloysite nanotube (HNT)-based HNTs@Fe3O4 nanocomposite (NCs) and then anchored the Janus Au-Ni or isotropic Au nanoparticles (NPs) to the surface of external wall of sulfydryl modified magnetic nanotubes. The characterization by physical methods authenticates the successful fabrication of two different magnetic HNTs@Fe3O4@Au and HNTs@Fe3O4@Au-Ni NCs. The catalytic activity and recyclability of the two NCs have been evaluated considering the degradation of Congo red (CR) and 4-nitrophenol (4-NP) using sodium borohydride as a model reaction. The results reveal that the symmetric Au NPs participated NCs display low activity in the degradation of the above organic dyes. However, a detailed kinetic study demonstrates that the employ of bimetallic Janus Au-Ni NPs in the NCs indicates enhanced catalytic activity, owing to the structurally specific nature. Furthermore, the magnetic functional NCs reported here can be used as recyclable catalyst which can be recovered simply by magnet. PMID:26852228

  9. Silver nanoparticles of variable morphology synthesized in aqueous foams as novel templates

    Indian Academy of Sciences (India)

    Saikat Mandal; Sujatha K Arumugam; Renu Pasricha; Murali Sastry

    2005-08-01

    In this paper, we describe the synthesis of silver nanocrystals within aqueous foams as a template. More specifically, we show that aqueous Ag+ ions may be electrostatically complexed with the anionic surfactants aerosol OT (sodium bis-2-ethylhexyl-sulfosuccinate, (AOT) and sodium dodecyl sulphate (SDS)) in a highly stable liquid foam. After drainage of the foam, the silver ions are reduced in situ by introducing sodium borohydride into the foam by capillary flow. This leads to the formation of silver nanoparticles of spherical, tape- and sheet-like morphology in the foam. The structure of the foam is extremely complex and presents reaction sites of different spatial extent. The differences in foam reaction–site geometry are believed to be responsible for the morphology variation in the silver nanoparticles observed. The silver nanoparticles are observed to be extremely stable in solution suggesting that the AOT or SDS molecules stabilize them. This approach appears promising for application in large-scale synthesis of nanoparticles and may be readily extended to other chemical compositions.

  10. Fabrication of CdTe/Si heterojunction solar cell

    Science.gov (United States)

    Bera, Swades Ranjan; Saha, Satyajit

    2016-01-01

    A simple cost effective method is preferred to grow nanoparticles of CdTe. Nanoparticles of CdTe are grown by simple chemical reduction route using EDA as capping agent and Sodium Borohydride as reducing agent. The grown nanoparticles are characterized using transmission electron microscopy (TEM), X-ray diffraction, optical absorption, and photoluminescence study. From optical absorption study, the band-gap was found to be 2.46 eV. From TEM study, the average particle size was found to be within 8-12 nm which confirms the formation of CdTe nanoparticles. Pl spectra indicate the luminescence from surface states at 2.01 eV, which is less compared to the increased band-gap of 2.46 eV. The grown nanoparticles are used to fabricate a heterojunction of CdTe on P-Si by a spin coating technique for solar cell fabrication in a cost effective way. I-V characteristics of the grown heterojunction in dark as well as under light are measured. Efficiency and fill-factor of the device are estimated.

  11. Chelant extraction and REDOX manipulation for mobilization of heavy metals from contaminated soils

    International Nuclear Information System (INIS)

    Was the result of open burning and open detonation of chemical agents and munitions in the Toxic Burning Pits area at J-Field, located in the Edgewood Area of Aberdeen Proving Ground in Harford County, Maryland, soils have been contaminated with heavy metals. Simultaneous extraction is complicated because of the multitude of contaminant forms that exist. This paper uses data from a treatability study performed at Argonne National Laboratory to discuss and compare several treatment methods that were evaluated for remediating metals-contaminated soils. J-Field soils were subjected to a series of treatability experiments designed to determine the feasibility of using soil washing/soil flushing, enhancements to soil washing/soil flushing, solidification/stabilization, and electrokinetics for remediating soils contaminated with metals. Chelating and mobilizing agents evaluated included ammonium acetate, ethylenediaminetetraacetic acid, citric acid, Citranox, gluconic acid, phosphoric acid, oxalic acid, and nitrilotriacetic acid, in addition to pH-adjusted water. REDOX manipulation can maximize solubilities, increase desorption, and promote removal of heavy metal contaminants. Reducing agents that were studied included sodium borohydride, sodium metabisulfite, and thiourea dioxide. The oxidants studied included hydrogen peroxide, sodium percarbonate, sodium hypochlorite, and potassium permanganate. This paper summaries the results from the physical/chemical characterization, soil washing/soil flushing, and enhancements to soil washing/soil flushing portions of the study

  12. Determination of copper, molybdenum and selenium in biological reference materials by inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    In a contribution to the elemental characterization of 10 new reference materials, Bovine Muscle Powder (136), Corn Starch (162), Hard Red Spring Wheat Flour (165), Soft Winter Wheat Flour (166), Whole Milk Powder (183), Wheat Gluten (184), Corn Bran (186). Durum Wheat Flour (187), Whole Egg Powder (188) and Microcrystalline Cellulose (189), the total concentrations of Cu, Mo and Se were determined by the application of an analytical method based on isotope dilution inductively coupled plasma mass spectrometry. Cu and Mo contents were quantified by measurement of 65Cu/63Cu and 97Mo/100Mo isotopic ratios following spiking with 65Cu and 97Mo and digestion with nitric acid. Selenium was separated as hydrogen selenide from the matrix using sodium borohydride after spiking with 82Se and acid digestion-dry ashing and quantified by measurement of the 82Se/78Se isotopic ratio. Comparison of these results with those from a variety of other methods and assessment of the procedures using certified reference materials indicated that the determinations of Cu, Mo and Se were performed without analytical bias. (orig.)

  13. Two-dimensional analysis of metabolically and cell surface radiolabeled proteins of some human lymphoid and myeloid leukemia cell lines. II

    International Nuclear Information System (INIS)

    Cell surface glycoproteins, radiolabelled by the sodium metaperiodate/tritiated borohydride technique, and cell phosphoproteins, metabolically radiolabelled with 32P-orthophosphate were analyzed by two-dimensional electrophoretic analysis in some myeloid and lymphoid leukemia cell lines. Some markedly expressed major glycoproteins were predominant in some of the cell lines (such as 95k and 100k glycoproteins with marked charge heterogeneity in non-T, non-B acute lymphoblastic leukemia cell lines NALM 6 and NALM 16), but markedly quantitatively reduced in other examined cell lines, such as lymphoblastoid cell line UHKT 34/2. 32P-orthophosphate radiolabelled phosphoprotein two-dimensional patterns of the examined lymphoid leukemia cell lines were essentially similar, with some minor differences, in examined lymphoid and myeloid leukemia cell lines, such as marked expression of a series of large phosphoproteins in the molecular weight range 80-100k in lymphoid cell lines and almost complete absence of these phosphoproteins on the examined myeloid leukemia cell lines. Another configuration of acidic phosphoproteins (30-35k) exhibited individual cell line variability and differences between both individual myeloid leukemia cell lines and between the lymphoid and myeloid cell lines examined. (author) 2 figs., 15 refs

  14. Production of Platinum Atom Nanoclusters at One End of Helical Plant Viruses

    Directory of Open Access Journals (Sweden)

    Yuri Drygin

    2013-01-01

    Full Text Available Platinum atom clusters (Pt nanoparticles, Pt-NPs were produced selectively at one end of helical plant viruses, tobacco mosaic virus (TMV and potato virus X (PVX, when platinum coordinate compounds were reduced chemically by borohydrides. Size of the platinum NPs depends on conditions of the electroless deposition of platinum atoms on the virus. Results suggest that the Pt-NPs are bound concurrently to the terminal protein subunits and the 5′ end of encapsidated TMV RNA. Thus, a special structure of tobacco mosaic virus and potato X virus particles with nanoparticles of platinum, which looks like a push-pin with platinum head and virus needle, was obtained. Similar results were obtained with ultrasonically fragmented TMV particles. By contrast, the Pt-NPs fully filled the central axial hole of in vitro assembled RNA-free TMV-like particles. We believe that the results presented here will be valuable in the fundamental understanding of interaction of viral platforms with ionic metals and in a mechanism of nanoparticles formation.

  15. Polyacrylonitrile Fibers Anchored Cobalt/Graphene Sheet Nanocomposite: A Low-Cost, High-Performance and Reusable Catalyst for Hydrogen Generation.

    Science.gov (United States)

    Zhang, Fei; Huang, Guoji; Hou, Chengyi; Wang, Hongzhi; Zhang, Qinghong; Li, Yaogang

    2016-06-01

    Cobalt and its composites are known to be active and inexpensive catalysts in sodium borohydride (NaBH4) hydrolysis to generate clean and renewable hydrogen energy. A novel fiber catalyst, cobalt/graphene sheet nanocomposite anchored on polyacrylonitrile fibers (Co/GRs-PANFs), which can be easily recycled and used in any reactor with different shapes, were synthesized by anchoring cobalt/graphene (Co/GRs) on polyacrylonitrile fibers coated with graphene (GRs-PANFs) at low temperature. The unique structure design effectively prevents the inter-sheet restacking of Co/GRs and fully exploits the large surface area of novel hybrid material for generate hydrogen. And the extra electron transfer path supplied by GRs on the surface of GRs-PANFs can also enhance their catalysis performances. The catalytic activity of the catalyst was investigated by the hydrolysis of NaBH4 in aqueous solution with GRs-PANFs. GRs powders and Co powders were used as control groups. It was found that both GRs and fiber contributed to the hydrogen generation rate of Co/GRs-PANFs (3222 mL x min(-1) x g(-1)), which is much higher than that of cobalt powders (915 mL x min(-1) x g(-1)) and Co/GRs (995 mL x min(-1) x g(-1)). The improved hydrogen generation rate, low cost and uncomplicated recycling make the Co/GRs-PANFs promising candidate as catalysts for hydrogen generation. PMID:27427607

  16. Facile solvothermal synthesis of highly active and robust Pd1.87Cu0.11Sn electrocatalyst towards direct ethanol fuel cell applications

    Science.gov (United States)

    Jana, Rajkumar; Dhiman, Shikha; Peter, Sebastian C.

    2016-08-01

    Ordered intermetallic Pd1.87Cu0.11Sn ternary electrocatalyst has been synthesized by sodium borohydride reduction of precursor salts Pd(acac)2, CuCl2.2H2O and SnCl2 using one-pot solvothermal synthesis method at 220 °C with a reaction time of 24 h. To the best of our knowledge, here for the first time we report surfactant free synthesis of a novel ordered intermetallic ternary Pd1.87Cu0.11Sn nanoparticles. The ordered structure of the catalyst has been confirmed by powder x-ray diffraction, transmission electron microscopy (TEM). Composition and morphology of the nanoparticles have been confirmed through field emission scanning electron microscopy, energy-dispersive spectrometry and TEM. The electrocatalytic activity and stability of the ternary electrocatalyst towards ethanol oxidation in alkaline medium was investigated by cyclic voltammetry and chronoamperometry techniques. The catalyst is proved to be highly efficient and stable upto 500th cycle and even better than commercially available Pd/C (20 wt%) electrocatalysts. The specific and mass activity of the as synthesized ternary catalyst are found to be ∼4.76 and ∼2.9 times better than that of commercial Pd/C. The enhanced activity and stability of the ordered ternary Pd1.87Cu0.11Sn catalyst can make it as a promising candidate for the alkaline direct ethanol fuel cell application.

  17. Determination of total homocysteine in human serum by capillary gas chromatography with sulfur-specific detection by double focusing ICP-MS.

    Science.gov (United States)

    de la Flor St Rèmy, R R; Montes-Bayón, M; Sanz-Medel, A

    2003-09-01

    A selective and sensitive method for determination of total homocysteine (Hcy) in human serum, by gas chromatography coupled to ICP-MS(HR), has been developed. After reduction of the sample with sodium borohydride the liberated Hcy and other aminothiols, such as cysteine (Cys) and methionine (Met), were converted to their N-trifluoroacetyl (TFA)- O-isopropyl derivatives and these were injected into a gas chromatograph equipped with an HP-5 capillary column. Detection was carried out by means of a double-focusing inductively coupled plasma mass spectrometer (DF-ICP-MS) monitoring (32)S at m/Delta m (resolving power)=3000. The transfer line used to transport the analytes from the GC column to the ICP-MS had previously been developed in our laboratory. The different parameters affecting the derivatisation process were optimised, as were the instrumental operating conditions. This optimised GC-ICP-MS(HR) method was successfully applied to the determination of total homocysteine in human serum-values obtained were in agreement with data reported in the literature. Quantitative recoveries and good precision were obtained for spiked human serum, demonstrating the suitability of the method for quantitative determination of total homocysteine in serum. PMID:12844208

  18. A new method for manufacturing graphene and electrochemical characteristic of graphene-supported Pt nanoparticles in methanol oxidation

    Science.gov (United States)

    Kakaei, Karim; Zhiani, Mohammad

    2013-03-01

    We report a Pt/graphene catalyst for the methanol oxidation. Graphene is synthesized from graphite electrodes using ionic liquid-assisted electrochemical exfoliation. Graphene-supported Pt electrocatalyst is then reduced by sodium borohydride with ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) as a stabilizing agent to prepare highly dispersed Pt nanoparticles on carbon graphene to use as methanol oxidation in direct methanol fuel cell (DMFC) catalysts. X-ray diffractometer and scanning electron microscopy technique are used to investigate the crystallite size and the surface morphologies respectively. The electrochemical characteristics of the Pt/graphene and commercial Pt/C catalysts are investigated by cyclic voltammetry (CV) in nitrogen saturated sulfuric acid aqueous solutions and in mixed sulfuric acid and methanol aqueous solutions. The catalytic activities of the Pt/graphene and Pt/C electrodes for methanol oxidation is 1315 A g-1 Pt and 725 A g-1 Pt, which can be revealed the particular properties of the exfoliated graphene supports. Furthermore, Pt/graphene exhibited a better sensitivity, signal-to-noise ratio, and stability than commercial Pt/C.

  19. Direct preparation of well-dispersed graphene/gold nanorod composites and their application in electrochemical sensors for determination of ractopamine

    International Nuclear Information System (INIS)

    Well-dispersed graphene/gold nanorod (G/GNR) composites were synthesized by directly reducing a mixture of graphene and gold growth solution with sodium borohydride. The synthesized G/GNR composites were characterized by ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy, and the composites were observed by transmission electronic microscopy, which revealed that the GNRs were self-assembled onto the surface of graphene sheets. Glassy carbon electrodes were modified with G/GNR composites to construct a ractopamine electrochemical sensor. A sensitive, rapid, and simple electrochemical method was developed for the detection of ractopamine based on the strong enhancement effect of G/GNRs. The peak currents varied linearly with the concentration of ractopamine over the range of 1 × 10−9 to 2.7 × 10−6 mol L−1, and the detection limit was 5.1 × 10−10 mol L−1 (S/N = 3). This method was applied to detect the content of ractopamine in swine urine samples, and the recovery was in the range of 99.2 to 107.3%

  20. Chitosan based polymer matrix with silver nanoparticles decorated multiwalled carbon nanotubes for catalytic reduction of 4-nitrophenol.

    Science.gov (United States)

    Alshehri, Saad M; Almuqati, Turki; Almuqati, Naif; Al-Farraj, Eida; Alhokbany, Norah; Ahamad, Tansir

    2016-10-20

    A novel catalyst for the reduction of 4-nitrophenol (4-NP) was prepared using carboxyl group-functionalized multiwalled carbon nanotubes (MWCNTs), polymer matrix, and silver nanoparticles (AgNPs). The AgNPs were prepared by the reduction of silver nitrate by trisodium citrate in the MWCNTs-polymer nanocomposite; the size of the synthesized AgNPs was found to be 3nm (average diameter). The synthesized nanocomposites were characterized using several analytical techniques. Ag@MWCNTs-polymer composite in the presence of sodium borohydride (NaBH4) in aqueous solution is an effective catalyst for the reduction of 4-NP. The apparent kinetics of reduction has a pseudo-first-order kinetics, and the rate constant and catalytic activity parameter were found to be respectively 7.88×10(-3)s(-1)and 11.64s(-1)g(-1). The MWCNTs-polymer nanocomposite renders stability to AgNPs against the environment and the reaction medium, which means that the Ag@MWCNTs-polymer composite can be re-used for many catalytic cycles. PMID:27474552

  1. Preparation and characterization of Pt-CeO2/C and Pt-TiO2/C electrocatalysts with improved electrocatalytic activity for methanol oxidation

    Science.gov (United States)

    Hameed, R. M. Abdel; Amin, R. S.; El-Khatib, K. M.; Fetohi, Amani E.

    2016-03-01

    Pt-TiO2/C and Pt-CeO2/C electrocatalysts were synthesized by solid state reaction of TiO2/C and CeO2/C powders using intermittent microwave heating, followed by chemical reduction of platinum ions using mixed reducing agents of ethylene glycol and sodium borohydride. The crystal structure, surface morphology and chemical composition of prepared electrocatalysts were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The phase angle values of different Pt diffraction planes in Pt-TiO2/C and Pt-CeO2/C were shifted in the positive direction relative to those in Pt/C. Pt particles with diameter values of 3.06 and 2.78 nm were formed in Pt-TiO2/C and Pt-CeO2/C, respectively. The electrochemical performance of prepared electrocatalysts was examined using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Pt-CeO2/C showed an enhanced oxidation current density when compared to Pt/C. Long time oxidation test at Pt-TiO2/C and Pt-CeO2/C revealed their improved stability. Lower charge transfer resistance values were estimated at Pt-metal oxide/C electrocatalysts.

  2. Influence of Sn on the magnetic ordering of Ni-Sn alloy synthesized using chemical reduction method

    Science.gov (United States)

    Dhanapal, K.; Narayanan, V.; Stephen, A.

    2016-05-01

    The Ni-Sn alloy was synthesized using borohydride assisted chemical reduction method. The composition of the synthesized alloy was determined using atomic absorption spectroscopy which revealed that the observed composition of Sn is high when compared to the initial composition. The ultrafine particles are clearly observed from field emission scanning electron microscope for all the sample. The X-ray diffraction measurement confirmed that the as-synthesized samples are of amorphous like nature while the samples annealed at 773 K showed crystalline nature. The Fourier transform infrared spectroscopy confirmed metallic bond stretching in the alloy samples. The crystallization and phase transition temperature was observed from differential scanning calorimetry. The shift in the crystallization temperature of Ni with increasing percentage of Sn was observed. The vibrating sample magnetometer was employed to understand the magnetic behavior of the Ni-Sn alloy. As-synthesized alloy samples showed paramagnetic nature while the annealed ones exhibit the soft ferromagnetic, antiferromagnetic and paramagnetic nature. The saturation magnetization value and magnetic ordering in the Ni-Sn alloys depend on the percentage of Sn present in the alloy.

  3. Fabrication of Bi-Fe3O4@RGO hybrids and their catalytic performance for the reduction of 4-nitrophenol

    International Nuclear Information System (INIS)

    Nanocatalysts are frequently connected to magnetic nanoparticles. These composites are easy to be retrieved from the reaction system under a magnetic field because of their magnetic properties. Magnetic separation is particularly promising in industry since it can solve many issues present in filtration, centrifugation, or gravitation separation. Herein, a facile method to prepare bismuth and Fe3O4 nanoparticles loaded on reduced graphene oxide magnetic hybrids (Bi-Fe3O4@RGO) using soluble starch as a dispersant is demonstrated. The magnetic Fe3O4 nanoparticles were synthesized by the co-precipitation of Fe2+ and Fe3+ ions, and Bi nanoparticles were fabricated by the redox reactions between sodium borohydride and ammonium bismuth citrate in the presence of soluble starch. Transmission electron microscopy images demonstrate that the average diameter of the Fe3O4 nanoparticles is about 5 nm and the diameters of Bi nanoparticles range from 10 to 20 nm. The magnetic Bi-Fe3O4@RGO hybrids exhibit high catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 with a first-order rate constant (K) of 0.00808 s−1 and is magnetically recyclable for at least five cycles. This strategy provides an efficient and recyclable catalyst for the use in environmental protection applications

  4. Attachment of noble metal nanoparticles to conducting polymers containing sulphur - preparation conditions for enhanced electrocatalytic activity

    International Nuclear Information System (INIS)

    Taking advantage of the spontaneous deposition of noble metals on polymers containing sulphur, the inclusion of gold and platinum in poly(3-methylthiophene) and poly(3,4-ehylenedioxythiophene) (PEDOTh) layers, achieved by immersion of the polymer into the metal nanoparticles suspension, is reported in the present work. Platinum and gold nanoparticles (NPs), with diameters between 3 and 17 nm, have been prepared from colloidal methods (citrate or borohydride reduction in the presence of citrate capping agent) and characterized by transmission electron microscopy, ultraviolet-visible spectrophotometry and X-ray diffraction (XRD). The electropolymerization was carried out under potentiostatic and potentiodynamic conditions, imparting distinct morphologies, as revealed by atomic force microscopy. After polymer films immersion in the colloidal solutions, evidence of the NPs confinement and distribution was provided by XRD analysis and scanning electron microscopy. For thin layers, the quantity of attached metal NPs could be estimated from quartz crystal microbalance data collected throughout the films immersion.The influence of the polymer type and morphology, NPs nature, size and incorporated amount on the electrocatalytic activity of the so-prepared modified electrodes towards the hydrazine oxidation, in phosphate buffer solution, has been investigated by cyclic voltammetry. The results clearly show the superior properties of potentiodynamically prepared PEDOTh films attaching very small (3 nm) freshly prepared Pt-NPs.

  5. Topological disposition of the sequences -QRKIVE- and -KETYY in native (Na+ + K+)-ATPase

    International Nuclear Information System (INIS)

    The dispositions with respect to the plane of the membrane of lysine-905 in the internal sequence -EQRKIVE- and of lysine-1012 in the carboxy-terminal sequence -RRPGGWVEKETYY of the α-polypeptide of sodium and potassium ion activated adenosinetriphosphatase have been determined. These lysines are found in peptides released from the intact α-polypeptide by the extracellular protease from Staphylococcus aureus strain V8 and by trypsin, respectively. Synthetic peptides containing terminal sequences of these were used to prepare polyclonal antibodies, which were then used to prepare immunoadsorbents directed against the respective peptides. Sealed, right-side-out membrane vesicles containing native (Na+ + K+)-ATPase were labeled with pyridoxal phosphate and sodium [3H]borohydride in the absence or presence of saponin. The labeled α-polypeptide was isolated from these vesicles and digested with appropriate proteases. The incorporation of radioactivity into the peptides binding to the immunoadsorbent directed against the sequence pyrERXIVE increased 3-fold int the presence of saponin as a result of the increased accessibility of this portion of the protein to the reagent when the vesicles were breached by saponin; hence, this sequence is located on the cytoplasmic face of the membrane. It was inferred that the carboxy-terminal sequence -KETYY is on the extracytoplasmic face since the incorporation of radioactivity into peptides binding to the immunoadsorbent directed against the sequence -ETYY did not change when the vesicles were breached with saponin

  6. Synthesis and Characterization of Ti-Phenyl at SiO2 Core-Shell Nanoparticles Catalyst

    International Nuclear Information System (INIS)

    This study highlights the potential use of Ti-Phenyl at SiO2 core-shell nanoparticles as heterogeneous catalysis in oxidation reaction. The Ti-Phenyl at SiO2 was synthesized by reduction of TiCl4 and diazonium salt with sodium borohydride to produce phenyl titanium nanoparticles (Ti-Phenyl), followed by the silica shell coating using tetraethyl orthosilicate (TEOS). The Ti-Phenyl at SiO2 nanoparticles were characterized by Fourier transform infrared (FTIR) spectrometer, diffuse reflectance (DR) UV-visible spectrometer, thermogravimetric analyzer (TGA), X-ray diffraction (XRD) spectrometer, field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The core-shell size of Ti-Phenyl at SiO2 was in the range of 40 to 100 nm with its core composed with an agglomeration of Ti-Phenyl. The Ti-Phenyl at SiO2 was active as a catalyst in the liquid phase epoxidation of 1-octene with aqueous hydrogen peroxide as an oxidant. (author)

  7. In-situ reduction of monodisperse nanosilver on hierarchical wrinkled mesoporous silica with radial pore channels and its antibacterial performance.

    Science.gov (United States)

    Wan, Xuejuan; Zhuang, Lulu; She, Boxi; Deng, Yuanming; Chen, Dazhu; Tang, Jiaoning

    2016-08-01

    Monodisperse silver nanoparticles (Ag NPs) were facilely loaded on the inner and outer surface of hierarchical wrinkled mesoporous silica (WMSs) via an in situ chemical reduction, and the antibacterial capacity of the obtained nanocomposite was investigated in detail. Typical sulfydryl-functionalized wrinkled mesoporous silica nanoparticle with radical pore channels was firstly prepared through sol-gel technique with cetyltrimethylammonium bromide (CTAB) as the templating surfactant. After sulfonation of the as-prepared WMSs, Ag(+) ions were then densely locked up on the inner and outer surface of WMSs via electrostatic interactions. Well distributed Ag NPs (ca. 3-5nm) on WMSs without any agglomeration were finally obtained via a simple in situ reduction reaction with sodium borohydride. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) test indicated that the obtained products can achieve durable and much better antibacterial performance both against Gram-negative bacterium Escherichia coli (E. coli) and Gram-positive bacterium Staphylococcus aureus (S. aureus) comparing to pure colloidal silver nanoparticles, which rendered them as favorable candidate for the development of effective antibacterial agents. PMID:27157758

  8. Impact of reaction parameters on the chemical profile of 3,4-methylenedioxymethamphetamine synthesized via reductive amination: target analysis based on GC-qMS compared to non-targeted analysis based on GC×GC-TOF-MS.

    Science.gov (United States)

    Schäffer, M; Dieckmann, S; Pütz, M; Kohles, T; Pyell, U; Zimmermann, R

    2013-12-10

    The most common clandestine manufacturing procedure for the ecstasy derivative 3,4-methylenedioxymethamphetamine (MDMA), is the reductive amination of piperonylmethylketone (PMK) via platinum(IV) oxide/hydrogen. Deviations of the reaction conditions during the synthesis may result in different chemical profiles of the products. The chemical analysis of these profiles is an important objective for forensic drug intelligence. In this work we studied the impact of a systematic variation of the hydrogenation time, the reaction temperature and the precursor batch on the resulting organic chemical profiles of the MDMA bases and MDMA hydrochlorides. Target analysis was based on a gas chromatography mass spectrometry (GC-MS) method which was harmonized during the European project CHAMP.(2) In addition, samples were analyzed by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) and subjected to non-targeted data analysis for a comprehensive analysis of the complete profiles. The reaction temperature, followed by the used precursor batch, revealed the highest impact on the chemical profile. The effect on individual impurity compounds is discussed in detail. With respect to the interpretation of the data, the profiles were compared to the profiles of MDMA samples obtained by reductive amination using sodium borohydride ("cold method") and aluminium/mercury amalgam as alternative reducing agents. Non-targeted analysis revealed that the discrimination according to the synthetic route and the batch of precursor used for the synthesis strongly depends on the selected target compounds. PMID:24314521

  9. Fast and facile preparation of CTAB based gels and their applications in Au and Ag nanoparticles synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Ravi Kant, E-mail: rkupadhyay85@gmail.com [Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India); Soin, Navneet, E-mail: n.soin@bolton.ac.uk [Knowledge Centre for Materials Chemistry (KCMC), Institute for Materials Research and Innovation (IMRI), University of Bolton, Deane Road, Bolton BL3 5AB (United Kingdom); Saha, Susmita, E-mail: ssaha@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Barman, Anjan, E-mail: abarman@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Sinha Roy, Susanta, E-mail: susanta.roy@snu.edu.in [Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India)

    2015-04-15

    We have demonstrated that the gel-like mesophase of Cetyltrimethylammonium bromide (CTAB) can be synthesized by judicial adjustment of water to surfactant molar ratio (W{sub 0}), without using any additional salts, gelating agents or co-surfactants. Gel formation was found to be highly dependent on the water to surfactant molar ratio (W{sub 0}), with the lowest value of W{sub 0} (41.5) resulting in rapid gel formation. Environmental scanning electron microscope (ESEM) analysis revealed that the gel was comprised of interconnected cylindrical structures. The presence of hydrogen bonding in the gel-like mesophase was confirmed by Fourier Transform Infrared spectroscopy (FTIR) analysis. Rheology measurements revealed that all the gel samples were highly viscoelastic in nature. Furthermore, Au and Ag containing CTAB gels were explored as precursors for the preparation of spherical Gold (Au) and Silver (Ag) nanoparticles using Sodium borohydride (NaBH{sub 4}) as reducing agent. The effects of NaBH{sub 4} concentration on the particle size and morphology of the Au and Ag nanoparticles have also been studied. - Highlights: • A facile synthesis of CTAB based gel-like mesophase is reported. • CTAB gels were obtained by adjusting water to surfactant molar ratio (W{sub 0}). • FTIR analysis revealed that hydrogen bonding plays a key role in gel formation. • Au, Ag nanoparticles were synthesized by using CTAB gel and NaBH{sub 4}.

  10. Detection of Selenium Speciation in Water and Soil Samples by Hydride Generation Techniques Spectrometer

    International Nuclear Information System (INIS)

    Speciation of Se(IV) and Se(VI) is studied using a hydride generation method. The determination of traces of selenium at ng/mL concentration ranges has been introduced using solution of hydrochloric acid and sodium borohydride in the hydride system, which is attached to the atomic absorption spectrometer (AAS) system. Several parameters such as the ratio of hydrochloric acid concentration, type and amount of acid and the reaction temperature are optimized by using of 50 ng/mL of Se(IV) standard solution. The calibration curve is linear from 0 to 1000 ng/mL of Se(IV). The relative standard deviation (RSD%) of the determination is (1.93%) and the detection limit is 10.6 ng/mL. The method is applied using environmental water and soil samples. For conversion of Se(VI) to Se(IV), 4 mol/L hydrochloric acid is added with NaBH4 to the samples

  11. Ultrasound-assisted synthesis of nanosized zero-valent iron for metal cations extraction and wastewater treatment applications

    Science.gov (United States)

    Mikhailov, I. Yu; Lysov, D. V.; Levina, V. V.; Mazov, I. N.; Gusev, A. A.; Yudintseva, T. I.; Kuznetsov, D. V.

    2016-01-01

    Nanosized zero-valent iron has shown good results in wastewater treatment and activation of physicochemical processes. Its applications in modern industry are complicated by high production costs of nanomaterials produced via existing synthesis routes. Therefore there is a need of cheap and high-productive methods of nanosized zero-valent iron with advanced functional properties. Improvement of oxidative conditions with additions may find its place in extraction of rare-earth metals, where high cost of nanomaterials could be viable. In this paper we studied an effect of ultrasonic irradiation on specific surface area and particle size of nanosized zero-valent iron synthesized by methods of chemical precipitation with high- temperature reduction in hydrogen flow and sodium borohydride reduction. Obtained results showed significant decrease of particle size and differences in particles morphology depending on presence of ultrasonication during synthesis and on chosen method. For ultrasonic-assisted synthesis with 100% amplitude, particle size calculated from specific surface area was 70 nm for sample synthesized by chemical precipitation with high-temperature reduction and 35 nm for borohydide reduction method compared to 63 nm for reference sample without ultrasonication.

  12. Slurry analysis of cadmium and copper collected on 11-mercaptoundecanoic acid modified TiO2 core-Au shell nanoparticles by flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Separation/preconcentration of copper and cadmium using TiO2 core-Au shell nanoparticles modified with 11-mercaptoundecanoic acid and their slurry analysis by flame atomic absorption spectrometry were described. For this purpose, at first, titanium dioxide nanoparticles were coated with gold shell by reducing the chloroauric acid with sodium borohydride and then modified with 11-mercaptoundecanoic acid. The characterization of modified nanoparticles was performed using ultra-violet spectroscopy and dynamic light scattering. Copper and cadmium were then collected on the prepared sorbent by batch method. The solid phase loaded with the analytes was separated by centrifugation and the supernatant was removed. Finally, the precipitate was slurried and directly aspirated into the flame for the determination of analytes. Thus, elution step and its all drawbacks were eliminated. The effects of pH, amount of sorbent, slurry volume, sample volume and diverse ions on the recovery were investigated. After optimization of experimental parameters, the analytes in different certified reference materials and spiked water samples were quantitatively recovered with 5% RSD. The analytes were enriched up to 20-fold. Limits of detection (N = 10, 3σ) for copper and cadmium were 0.28 and 0.15 ng mL-1, respectively.

  13. Synthesis and optical properties of copper nanoparticles prepared by a chemical reduction method

    International Nuclear Information System (INIS)

    Copper nanoparticles, due to their interesting properties, low cost preparation and many potential applications in catalysis, cooling fluid or conductive inks, have attracted a lot of interest in recent years. In this study, copper nanoparticles were synthesized through the chemical reduction of copper sulfate with sodium borohydride in water without inert gas protection. In our synthesis route, ascorbic acid (natural vitamin C) was employed as a protective agent to prevent the nascent Cu nanoparticles from oxidation during the synthesis process and in storage. Polyethylene glycol (PEG) was added and worked both as a size controller and as a capping agent. Cu nanoparticles were characterized by Fourier transform infrared (FT-IR) spectroscopy to investigate the coordination between Cu nanoparticles and PEG. Transmission electron microscopy (TEM) and UV–vis spectrometry contributed to the analysis of size and optical properties of the nanoparticles, respectively. The average crystal sizes of the particles at room temperature were less than 10 nm. It was observed that the surface plasmon resonance phenomenon can be controlled during synthesis by varying the reaction time, pH, and relative ratio of copper sulfate to the surfactant. The surface plasmon resonance peak shifts from 561 to 572 nm, while the apparent color changes from red to black, which is partly related to the change in particle size. Upon oxidation, the color of the solution changes from red to violet and ultimately a blue solution appears

  14. Micromotor-based energy generation.

    Science.gov (United States)

    Singh, Virendra V; Soto, Fernando; Kaufmann, Kevin; Wang, Joseph

    2015-06-01

    A micromotor-based strategy for energy generation, utilizing the conversion of liquid-phase hydrogen to usable hydrogen gas (H2), is described. The new motion-based H2-generation concept relies on the movement of Pt-black/Ti Janus microparticle motors in a solution of sodium borohydride (NaBH4) fuel. This is the first report of using NaBH4 for powering micromotors. The autonomous motion of these catalytic micromotors, as well as their bubble generation, leads to enhanced mixing and transport of NaBH4 towards the Pt-black catalytic surface (compared to static microparticles or films), and hence to a substantially faster rate of H2 production. The practical utility of these micromotors is illustrated by powering a hydrogen-oxygen fuel cell car by an on-board motion-based hydrogen and oxygen generation. The new micromotor approach paves the way for the development of efficient on-site energy generation for powering external devices or meeting growing demands on the energy grid. PMID:25906739

  15. Polyelectrolyte induced formation of silver nanoparticles in copolymer hydrogel and their application as catalyst

    Energy Technology Data Exchange (ETDEWEB)

    He, Yongqiang [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Huang, Guanbo, E-mail: gbhuang2007@hotmail.com [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Pan, Zeng; Liu, Yue [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Gong, Qiaojuan; Yao, Chenzhong [Department of Applied Chemistry, Yuncheng University, Yuncheng 044000 (China); Gao, Jianping, E-mail: jianpingg@eyou.com [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China)

    2015-10-15

    Highlights: • A simple route for the in situ preparation of Ag nanoparticles has been developed. • The Ag loaded hydrogel showed catalytic activity for reduction of 4-nitrophenol. • The catalyst can be recovered by simple separation and showed good recyclability. - Abstract: A simple route for the in situ preparation of catalytically active Ag nanoparticles (NPs) in hydrogel networks has been developed. The electronegativity of the amide and carboxyl groups on the poly(acrylamide-co-acryl acid) chains caused strong binding of the Ag{sup +} ions which made the ions distribute uniformly inside the hydrogels. When the Ag{sup +} loaded hydrogels were immersed in NaBH{sub 4} solution, the Ag{sup +} ions on the polymer networks were reduced to Ag NPs. The resultant hydrogel showed good catalytic activity for the reduction of a common organic pollutant, 4-nitrophenol, with sodium borohydride. A kinetic study of the catalytic reaction was carried out and a possible reason for the decline of the catalytic performance with reuse is proposed.

  16. Design of Cobalt Nanoparticles with Tailored Structural and Morphological Properties via O/W and W/O Microemulsions and Their Deposition onto Silica

    Directory of Open Access Journals (Sweden)

    Gabriella Di Carlo

    2015-03-01

    Full Text Available Cobalt nanostructures with different size and morphology, i.e., spherical nanoparticles, nanorods, and particles arranged into elongated structures, were prepared using micelles and microemulsions as confined reaction media. The syntheses were carried out using three types of systems: aqueous surfactant solutions, oil-in water (O/W, and water-in-oil (W/O microemulsions. The influence of the surfactant and the precipitating agent used for synthesis was also investigated. For this purpose, cobalt nanostructures were prepared using different non-ionic surfactants, namely Synperonic® 10/6, Pluronic® P123 and a mixture of SPAN 20–TWEEN 80. Three different precipitating agents were used: sodium borohydride, sodium hydroxide, and oxalic acid. Our findings revealed that by changing the type of reaction media as well as the precipitating agent it is possible to modify the shape and size of the cobalt nanostructures. Moreover, the use of O/W microemulsion generates better results in terms of colloidal stability and uniformity of particle size with respect to W/O microemulsion. The different cobalt nanostructures were supported on commercial and mesoporous silica; transmission electron microscopy (TEM images showed that after deposition the Co nanocrystals remain well dispersed on the silica supports. This behavior suggests their great potential in catalytic applications.

  17. Facile synthesis of near-monodisperse Ag-Ni core-shell nanoparticles and their application for catalytic generation of hydrogen

    International Nuclear Information System (INIS)

    Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 ± 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H2 from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.

  18. Synthesis of diphenylalanine/cobalt oxide hybrid nanowires and their application to energy storage.

    Science.gov (United States)

    Ryu, Jungki; Kim, Sung-Wook; Kang, Kisuk; Park, Chan Beum

    2010-01-26

    We report the synthesis of novel diphenylalanine/cobalt(II,III) oxide (Co(3)O(4)) composite nanowires by peptide self-assembly. Peptide nanowires were prepared by treating amorphous diphenylalanine film with aniline vapor at an elevated temperature. They were hybridized with Co(3)O(4) nanocrystals through the reduction of cobalt ions in an aqueous solution using sodium borohydride (NaBH(4)) without any complex processes such as heat treatment. The formation of peptide/Co(3)O(4) composite nanowires was characterized using multiple tools, such as electron microscopies and elemental analysis, and their potential application as a negative electrode for Li-ion batteries was explored by constructing Swagelok-type cells with hybrid nanowires as a working electrode and examining their charge/discharge behavior. The present study provides a useful approach for the synthesis of functional metal oxide nanomaterials by demonstrating the feasibility of peptide/Co(3)O(4) hybrid nanowires as an energy storage material. PMID:20000841

  19. A high performance cobalt sulfide counter electrode for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Highlights: • CoS electrode is prepared by repetitive electrophoretic and ion exchange depositions. • The CoS has honeycomb-like structure, good catalytic activity and lower resistances. • DSSC with CoS-4AB obtains a PCE of 7.72%, higher than the cell with Pt electrode. - Abstract: A cobalt sulfide (CoS) thin film is deposited on fluorine doped SnO2 (FTO) glass by repetitive electrophoretic deposition (EPD) and ion exchange deposition (IED), then the thin film is treated with sodium borohydride or/and sulfuric acid solution. The film is used as the counter electrode of dye-sensitized solar cells (DSSCs), and is characterized by field emission scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and Tafel measurements. The results show that the CoS counter electrode has a honeycomb-like morphology with large specific surface area, good catalytic activity for reduction of I3−, lower charge-transfer and series resistances, which result in the better electrochemical property of CoS counter electrodes. Under a simulated solar light irradiation of 100 mW cm−2, the DSSC based on the CoS counter electrode achieves a power conversion efficiency of 7.72%, thus, synthesized CoS can serve as an efficient Pt-free counter electrode material for DSSCs

  20. Electrical and Thermal Behavior of Copper-Epoxy Nano composites Prepared via Aqueous to Organic Phase Transfer Technique

    International Nuclear Information System (INIS)

    The preparation, electrical, and thermal behaviors of copper-epoxy nano composites are described. Cetyltrimethylammonium bromide- (CTAB-) stabilized copper (Cu) particles were synthesized via phase transfer technique. Isopropanol (IPA), sodium borohydride (NaBH4), and toluene solution of diglycidyl ether of bisphenol A (DGEBA) were used as transferring, reducing agent, and the organic phase, respectively. The UV-Vis absorbance spectra of all the sols prepared indicate that the presence of Cu particles with the particles transfer efficiency is ≥97%. The amount, size, and size distribution of particles in the organo sol were dependent on the content of organic solute in the organo sol. The composites were obtained upon drying the organo sols and these were then subjected to further studies on the curing, thermal, and electrical characteristic. The presence of Cu fillers does not significantly affect the completeness of the composite curing process and only slightly reduce the thermal stability of the composites that is >300 degree C. The highest conductivity value of the composites obtained is 3.06x10-2 Scm-1.

  1. FACILE GREEN SYNTHESIS OF GOLD NANOPARTICLES WITH GREAT CATALYTIC ACTIVITY USING ULVA FASCIATA

    Directory of Open Access Journals (Sweden)

    V. Sugantha Kumari

    2014-03-01

    Full Text Available We report a facile, green, and high yielding approache for the synthesis and stabilization of monodisperse gold nanoparticles (AuNPs using green seaweed Ulva fasciata extract. Characterization of the obtained AuNPs was performed using UV-visible, Fourier transform infrared (FTIR, X-ray diffraction (XRD and transmission electron microscopy (TEM. UV-visible absorption spectroscopy was used to determine the yield of the gold nanoparticles. The UV-visible absorption spectrum showed a characteristic optical peak of AuNPs at 541 nm. The X-ray diffraction pattern suggested the formation and crystallinity of AuNPs. Spherical AuNPs synthesized with an average particle size of 10 ± 3 nm were confirmed by TEM. FTIR analysis supported the role of phytochemicals of Ulva fasciata extract for bioreduction and stabilization of AuNPs. Moreover, the synthesized AuNPs exhibit remarkable catalytic efficiency by using the reduction of 4-nitroaniline by potassium borohydride in aqueous solution using UV-visible absorption spectroscopy. Catalytic reduction followed pseudo-first-order kinetics with respect to 4-Nitrophenol.

  2. Nanoscaled zero valent iron/graphene composite as an efficient adsorbent for Co(II) removal from aqueous solution.

    Science.gov (United States)

    Xing, Min; Wang, Jianlong

    2016-07-15

    A magnetic graphene, i.e., nanoscaled zero valent iron/graphene (0FG) composite, was prepared, characterized and applied for the removal of Co(II) from aqueous solution. The magnetic graphene (0FG) was synthesized through reduction of graphene oxide (GO) and ferrous ions by potassium borohydride. The kinetics and isotherms of Co(II) adsorption onto 0FG were investigated. The mechanism for Co(II) removal was proposed based on the Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and the X-ray absorption fine structure (XAFS) analysis. The results showed that pseudo second-order models and the Freundlich isotherm model fitted well with the data obtained. The adsorption capacity of 0FG was calculated from the Langmuir isotherm, which was 65.58, 101.60 and 134.27mg/g at 10, 20 and 30°C, respectively. Thermodynamic parameters suggested that the adsorption process was endothermic and spontaneous. Co(2+) was stabilized by γ-FeOOH/γ-Fe2O3/Fe3O4 on the surface of graphene sheets, forming CoFe2O4-like nanocrystals. The coordination numbers and interatomic distances indicated that Co(2+) mainly occupied the octahedral site, while pseudo-tetrahedral coordination may occur by dehydroxylation of Co(O,OH)6. Magnetic graphene is a potential adsorbent for Co(2+) removal. PMID:27115333

  3. Study of Methylene Blue Degradation by Gold Nanoparticles Synthesized within Natural Zeolites

    Directory of Open Access Journals (Sweden)

    Ericka Rodríguez León

    2016-01-01

    Full Text Available We carried out the in situ synthesis of gold nanoparticles inside a natural clinoptilolite-type zeolite matrix, using ascorbic acid as reducing agent. The microstructure of both zeolite and zeolite-gold nanocomposite was characterized by X-ray diffraction (XRD, Scanning Electron Microscopy (SEM, Scanning Transmission Electron Microscopy (STEM, and Energy-Dispersive X-ray Spectroscopy (EDS techniques. Size distribution as assessed by STEM indicated that 60% of gold nanoparticles measured less than 2.5 nm. Determination of the surface area by the BET method revealed a specific value of 27.35 m2/g. The catalytic activity of zeolite-gold regarding methylene blue degradation under different light-exposing conditions was evaluated by UV-Vis spectroscopy. The results indicated that 50% degradation was achieved in only 11 min in presence of sunlight. This reaction was faster in comparison with those obtained using a white LED light. A notable aspect of this study is that catalysis was carried out without the addition of any strong reducing agents, such as sodium borohydride (NaBH4.

  4. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    Science.gov (United States)

    Xingu-Contreras, E.; García-Rosales, G.; García-Sosa, I.; Cabral-Prieto, A.; Solache-Ríos, M.

    2015-06-01

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45∘ (2 𝜃), inferring the presence of nanocrystals of Fe2B as identified from Mössbauer Spectroscopy. The size of these Fe2B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ≥ 95 %.

  5. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    International Nuclear Information System (INIS)

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45∘ (2θ), inferring the presence of nanocrystals of Fe2B as identified from Mössbauer Spectroscopy. The size of these Fe2B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ≥ 95 %

  6. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Xingu-Contreras, E., E-mail: nyleve-18@hotmail.com; García-Rosales, G., E-mail: gegaromx@yahoo.com.mx [Instituto Tecnológico de Toluca (Mexico); García-Sosa, I., E-mail: irma.garcia@inin.gob.mx; Cabral-Prieto, A., E-mail: agustin.cabral@inin.gob.mx; Solache-Ríos, M., E-mail: marcos.solache@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química (Mexico)

    2015-06-15

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45{sup ∘} (2θ), inferring the presence of nanocrystals of Fe{sub 2}B as identified from Mössbauer Spectroscopy. The size of these Fe{sub 2}B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ≥ 95 %.

  7. Novel and efficient preparation of precursor [188Re(OH2)3(CO)3]+ for the labeling of biomolecules.

    Science.gov (United States)

    Park, Sang Hyun; Seifert, Sepp; Pietzsch, Hans-Jurgen

    2006-01-01

    A novel and efficient method for preparing 188Re(I) tricarbonyl precursor [188Re(OH2)3(CO)3]+ has been developed by reacting [188Re]perrhenate with Schibli's kit in the presence of borohydride exchange resin (BER) as a reducing agent and an anion scavenger. The precursor was produced in more than 97% yield by reacting a solution of tetrahydroborate exchange resin (BER, 3 mg), borane-ammonia (BH3.NH3, 3 mg), and potassium boranocarbonate (K2[H3BCO2], 3 mg) in 0.9% saline with a solution of sodium perrhenate (Na188ReO4) with up to 50 MBq and concentrated phosphoric acid (85%, 7 microL) at 60 degrees C for 15 min. HPLC and TLC revealed 0% unreacted [188Re]perrhenate ion and <3% of colloidal 188ReO2. Since the precursor is produced with high radiochemical purity and labeling efficiency under the milder conditions than those required for the conventional reducing agents, the latter can be replaced. PMID:16417272

  8. Electrochemistry of magnesium electrolytes in ionic liquids for secondary batteries.

    Science.gov (United States)

    Vardar, Gulin; Sleightholme, Alice E S; Naruse, Junichi; Hiramatsu, Hidehiko; Siegel, Donald J; Monroe, Charles W

    2014-10-22

    The electrochemistry of Mg salts in room-temperature ionic liquids (ILs) was studied using plating/stripping voltammetry to assess the viability of IL solvents for applications in secondary Mg batteries. Borohydride (BH4(-)), trifluoromethanesulfonate (TfO(-)), and bis(trifluoromethanesulfonyl)imide (Tf2N(-)) salts of Mg were investigated. Three ILs were considered: l-n-butyl-3-methylimidazolium (BMIM)-Tf2N, N-methyl-N-propylpiperidinium (PP13)-Tf2N, and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium (DEME(+)) tetrafluoroborate (BF4(-)). Salts and ILs were combined to produce binary solutions in which the anions were structurally similar or identical, if possible. Contrary to some prior reports, no salt/IL combination appeared to facilitate reversible Mg plating. In solutions containing BMIM(+), oxidative activity near 0.8 V vs Mg/Mg(2+) is likely associated with the BMIM cation, rather than Mg stripping. The absence of voltammetric signatures of Mg plating from ILs with Tf2N(-) and BF4(-) suggests that strong Mg/anion Coulombic attraction inhibits electrodeposition. Cosolvent additions to Mg(Tf2N)2/PP13-Tf2N were explored but did not result in enhanced plating/stripping activity. The results highlight the need for IL solvents or cosolvent systems that promote Mg(2+) dissociation. PMID:25248147

  9. Chemical synthesis of magnetic Fe-B and Fe-Co-B particles and chains

    International Nuclear Information System (INIS)

    With an objective to develop magnetic materials with high saturation magnetization for the Magnetically Assisted Chemical Separation (MACS) process the chemical synthesis of Fe-B and Fe-Co-B alloys by reducing iron and cobalt chloride solutions with potassium borohydride has been investigated systematically. The influence of the concentration of the reactants, applied magnetic field, reaction atmosphere, and method of mixing the reactants on the microstructure, particle size, composition and magnetic properties has been studied. Both M-B (M = Fe and Co) particles and elongated chains composed of nanometer size M-B particles have been obtained depending on the reaction conditions. The Fe-B samples exhibit saturation magnetization of MS of 120--190 emu/g, remanent magnetization Mr of 10--22 emu/g, and coercive field Hc of 400--900 Oe. A high MS value of 190 emu/g, which is close to the theoretical value of 218 emu/g for pure Fe, has been achieved particularly for samples with well-defined chain structures. Increasing the Co content in the Fe-Co-B alloys increases the boron content and thereby decreases the crystallinity and MS values although marginal increase in Hc (1,250 Oe) and Mr (36 emu/g) values could be made in some Fe-Co-B compositions. The chain structure with high MS may be attractive for other magnetic separation processes as well

  10. Y-shaped probe for convenient and label-free detection of microRNA-21 in vitro.

    Science.gov (United States)

    He, Kui; Liao, Rong; Cai, Changqun; Liang, Caishuang; Liu, Chan; Chen, Xiaoming

    2016-04-15

    A simple, highly selective, and label-free microRNA (miRNA) detection method based on l-alanine-reduced graphene oxide fluorescence quenching with a Y-shaped probe is proposed. The Y-shaped probe was synthesized by silver nitrate and a cytosine-rich molecular beacon (MB) in two terminals through sodium borohydride reduction, which generated a stronger fluorescent signal than ordinary DNA-templated silver nanoclusters (AgNCs). Meanwhile, the Y-shaped probe contained a single-stranded loop structure, which could be superbly adsorbed onto the surface of reduced graphene oxide (RGO) via π-π stacking interaction, and this special structure of the probe was designed to improve its sensitivity and selectivity. In addition, the quenching capacities of graphene oxide (GO) and RGO were compared in this research. The strong interaction between nucleobases of the loop structure and RGO nanosheet made the MB-AgNCs-RGO system exhibit minimal background fluorescence. In the presence of miRNA-21, the loop structure of the Y-shaped probe can hybridize with target miRNA-21; the molecular beacon encapsulated probe is far away from RGO surface and produces a detectable signal. The MB-AgNCs based approach provides a label-free avenue to detect miRNA with high selectivity and good reproducibility, which has a promising application in early clinical diagnosis and biomedical research. PMID:26854593

  11. Photochemical electronic doping of colloidal CdSe nanocrystals.

    Science.gov (United States)

    Rinehart, Jeffrey D; Schimpf, Alina M; Weaver, Amanda L; Cohn, Alicia W; Gamelin, Daniel R

    2013-12-18

    A method for electronic doping of colloidal CdSe nanocrystals (NCs) is reported. Anaerobic photoexcitation of CdSe NCs in the presence of a borohydride hole quencher, Li[Et3BH], yields colloidal n-type CdSe NCs possessing extra conduction-band electrons compensated by cations deposited by the hydride hole quencher. The photodoped NCs possess excellent optical quality and display the key spectroscopic signatures associated with NC n-doping, including a bleach at the absorption edge, appearance of a new IR absorption band, and Auger quenching of the excitonic photoluminescence. Although stable under anaerobic conditions, these spectroscopic changes are all reversed completely upon exposure of the n-doped NCs to air. Chemical titration of the added electrons confirms previous correlations between absorption bleach and electron accumulation and provides a means of quantifying the extent of electron trapping in some NCs. The generality of this photodoping method is demonstrated by initial results on colloidal CdE (E = S, Te) NCs as well as on CdSe quantum dot films. PMID:24289732

  12. Preparation and electrochemical characterization of polyaniline functionalized copper bridges carbon nanotube for supercapacitor applications.

    Science.gov (United States)

    Giri, Soumen; Das, Chapal Kumar

    2014-08-01

    Supercapacitor is an alternative power source due to its high energy density, fast charge/discharge time, low level of heating, safety, long-term operation stability. MWCNTs are used for supercapacitor applications due to their unique properties, structure, high surface area. In the present work nanocomposites were prepared from Cu modified MWCNTs (binary) from which ternary composite also prepared with HCI doped polyaniline (PANI). Cu modified MWCNTs were prepared by the reduction of copper sulphate with sodium borohydride in basic medium. The uniform coating of polymer, upon the Cu modified MWCNTs, was evidenced from the field emission scanning electron microscopic (FESEM) and high resolution transmission electron microscopic (HRTEM) images. The modification of MWCNTs with Cu, was confirmed from the X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Cyclic voltammetry (CV) measurement and charge discharge test shows higher capacitance for the ternary composites (264 F/g) compared to the binary system (125 F/g). The cyclic stability and retention of specific capacitance also shows the better result for ternary system. PMID:25936120

  13. The effect of hydrogen nanobubbles on the morphology of gold–gelatin bionanocomposite films and their optical properties

    International Nuclear Information System (INIS)

    Gold–gelatin bionanocomposite films are prepared by the reduction of gold ions by sodium borohydride in an aqueous solution. It is shown that both the solution and the films on glass substrates contain entrapped hydrogen micro- and nanobubbles with diameters in the range of 200 nm–3 μm. The optical properties of gold nanoparticles in the presence of gelatin and hydrogen nanobubbles are measured and simulated by using the discrete dipole approximation method. The composite films having micro- and nanobubble inclusions have been found to be very stable. The calculated localized surface plasmon resonance band is found in agreement with the experimental band position only when the presence of hydrogen bubbles around the gold nanoparticles is taken into account. The different morphological features engendered by the presence of the bubbles in the film (gelatin receptacles for the nanoparticles, gelatin hemispheres raised by the bubbles under the surface, cavities on the surface of the film, etc) are described in detail and considered for potential applications. This work is highly relevant to the new and exciting topic of nanobubbles on surfaces and interfaces. (paper)

  14. Cob(I)alamin reacts with sucralose to afford an alkylcobalamin: relevance to in vivo cobalamin and sucralose interaction.

    Science.gov (United States)

    Motwani, Hitesh V; Qiu, Shiran; Golding, Bernard T; Kylin, Henrik; Törnqvist, Margareta

    2011-04-01

    Vitamin B(12), viz., cyano- or hydroxo-cobalamin, can be chemically or enzymatically converted into the derivatives methyl- and adenosyl-cobalamin, which are complex organometallic cofactors associated with several cobalamin-dependent enzymes. The reduced form of vitamin B(12), cob(I)alamin {Cbl(I)}, obtained by reduction of hydroxocobalamin (OH-Cbl) with e.g. sodium borohydride, is one of the most powerful nucleophiles known. Cbl(I) was shown to react readily with the synthetic sweetener sucralose (1,6-dichloro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-galactopyranoside) in an aqueous system to form an alkylcobalamin (Suc-Cbl). This occurred by replacement of one of the three chlorine atoms of sucralose with a cobalamin moiety. The efficiency of trapping sucralose in presence of excess Cbl(I) was estimated to be >90%. Furthermore, in an in vitro study using human liver S9 with NADPH regeneration, in presence of OH-Cbl and sucralose, Suc-Cbl was shown to be formed. The Suc-Cbl was characterized primarily by LC-ESI(+)-MS/MS. Given the human consumption of sucralose from food and beverages, such a reaction between the sweetener and reduced vitamin B(12) could occur in vivo. PMID:21130828

  15. Solvent effects on Pt-Ru/C catalyst for methanol electro-oxidation

    Institute of Scientific and Technical Information of China (English)

    Jinwei Chen; Chunping Jiang; Hui Lu; Lan Feng; Xin Yang; Liangqiong Li; Ruilin Wang

    2009-01-01

    Alloying degree,particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent(s) used in the preparation process can affect the particle size and alloying degree of the object substance,which lead to a great positive impact on its properties. In this work,three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry (CV) and Chronoamperometry (CA). Pt-Ru/C catalyst prepared in H_2O or binary solvents of H_2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems,Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity,lower onset and peak potentials,compared with the above catalysts. Moreover,the catalyst prepared in ternary solvents of isopropanol,water and tetrahydrofuran had the smallest particle size,and the high alloying degree and the dispersion kept unchanged. Therefore,this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation.

  16. Facile synthesis of pentacle gold-copper alloy nanocrystals and their plasmonic and catalytic properties

    Science.gov (United States)

    He, Rong; Wang, You-Cheng; Wang, Xiaoyong; Wang, Zhantong; Liu, Gang; Zhou, Wei; Wen, Longping; Li, Qunxiang; Wang, Xiaoping; Chen, Xiaoyuan; Zeng, Jie; Hou, J. G.

    2014-07-01

    The combination of gold and copper is a good way to pull down the cost of gold and ameliorate the instability of copper. Through shape control, the synergy of these two metals can be better exploited. Here, we report an aqueous phase route to the synthesis of pentacle gold-copper alloy nanocrystals with fivefold twinning, the size of which can be tuned in the range from 45 to 200 nm. The growth is found to start from a decahedral core, followed by protrusion of branches along twinning planes. Pentacle products display strong localized surface plasmon resonance peaks in the near-infrared region. Under irradiation by an 808-nm laser, 70-nm pentacle nanocrystals exhibit a notable photothermal effect to kill 4T1 murine breast tumours established on BALB/c mice. In addition, 70-nm pentacle nanocrystals show better catalytic activity than conventional citrate-coated 5-nm Au nanoparticles towards the reduction of p-nitrophenol to p-aminophenol by sodium borohydride.

  17. Charge density modification of carboxylated cellulose nanocrystals for stable silver nanoparticles suspension preparation

    Energy Technology Data Exchange (ETDEWEB)

    Hoeng, Fanny; Denneulin, Aurore [Université Grenoble Alpes, LGP2 (France); Neuman, Charles [Poly-Ink (France); Bras, Julien, E-mail: julien.bras@grenoble-inp.fr [Université Grenoble Alpes, LGP2 (France)

    2015-06-15

    Synthesis of silver nanoparticles using cellulose nanocrystals (CNC) has been found to be a great method for producing metallic particles in a sustainable way. In this work, we propose to evaluate the influence of the charge density of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-oxidized CNC on the morphology and the stability of synthetized silver nanoparticles. Silver nanoparticles were obtained by sol–gel reaction using borohydride reduction, and charge density of TEMPO-oxidized CNC was tuned by an amine grafting. The grafting was performed at room temperature and neutral pH. Crystallinity and morphology were kept intact during the peptidic reaction on CNC allowing knowing the exact impact of the charge density. Charge density has been found to have a strong impact on shape, organization, and suspension stability of resulting silver particles. Results show an easy way to tune the charge density of CNC and propose a sustainable way to control the morphology and stability of silver nanoparticles in aqueous suspension.

  18. Three-dimensional cellulose sponge: Fabrication, characterization, biomimetic mineralization, and in vitro cell infiltration.

    Science.gov (United States)

    Joshi, Mahesh Kumar; Pant, Hem Raj; Tiwari, Arjun Prasad; Maharjan, Bikendra; Liao, Nina; Kim, Han Joo; Park, Chan Hee; Kim, Cheol Sang

    2016-01-20

    In this study, cellulose based scaffolds were produced by electrospinning of cellulose acetate (CA) solution followed by its saponification with NaOH/ethanol system for 24h. The resulting nonwoven cellulose mat was treated with sodium borohydride (SB) solution. In situ hydrolysis of SB solution into the pores of the membrane produced hydrogen gas resulting a three-dimensional (3D) cellulose sponge. SEM images demonstrated an open porous and loosely packed fibrous mesh compared to the tightly packed single-layered structure of the conventional electrospun membrane. 3D cellulose sponge showed admirable ability to nucleate bioactive calcium phosphate (Ca-P) crystals in simulated body fluid (SBF) solution. SEM-EDX and X-ray diffraction studies revealed that the minerals deposited on the nanofibers have the nonstoichiometric composition similar to that of hydroxyapatite, the mineralized component of the bone. 3D cellulose sponge exhibited the better cell infiltration, spreading and proliferation compared to 2D cellulose mat. Therefore, a facile fabrication of 3D cellulose sponge with improved mineralization represents an innovative strategy for the bone tissue engineering applications. PMID:26572341

  19. Theoretical study of C60 as catalyst for dehydrogenation in LiBH4.

    Science.gov (United States)

    Scheicher, Ralph H; Li, Sa; Araujo, C Moyses; Blomqvist, Andreas; Ahuja, Rajeev; Jena, Puru

    2011-08-19

    Complex light metal hydrides possess many properties which make them attractive as a storage medium for hydrogen, but typically catalysts are required to lower the hydrogen desorption temperature and to facilitate hydrogen uptake in the form of a reversible reaction. The overwhelming focus in the search for catalysing agents has been on compounds containing titanium, but the precise mechanism of their actions remains somewhat obscure. A recent experiment has now shown that fullerenes (C(60)) can also act as catalysts for both hydrogen uptake and release in lithium borohydride (LiBH(4)). In an effort to understand the involved mechanism, we have employed density functional theory to carry out a detailed study of the interaction between this complex metal hydride and the carbon nanomaterial. Considering a stepwise reduction of the hydrogen content in LiBH(4), we find that the presence of C(60) can lead to a substantial reduction of the involved H-removal energies. This effect is explained as a consequence of the interaction between the BH(x)( - ) complex and the C(60) entity. PMID:21788688

  20. Electronic Structure and Molecular Dynamics Calculations for KBH4

    Science.gov (United States)

    Papaconstantopoulos, Dimitrios; Shabaev, Andrew; Hoang, Khang; Mehl, Michael; Kioussis, Nicholas

    2012-02-01

    In the search for hydrogen storage materials, alkali borohydrides MBH4 (M=Li, Na, K) are especially interesting because of their light weight and the high number of hydrogen atoms per metal atom. Electronic structure calculations can give insights into the properties of these complex hydrides and provide understanding of the structural properties and of the bonding of hydrogen. We have performed first-principles density-functional theory (DFT) and tight-binding (TB) calculations for KBH4 in both the high temperature (HT) and low temperature (LT) phases to understand its electronic and structural properties. Our DFT calculations were carried out using the VASP code. The results were then used as a database to develop a tight-binding Hamiltonian using the NRL-TB method. This approach allowed for computationally efficient calculations of phonon frequencies and elastic constants using the static module of the NRL-TB, and also using the molecular dynamics module to calculate mean-square displacements and formation energies of hydrogen vacancies.

  1. Recovery of high purity precious metals from printed circuit boards

    International Nuclear Information System (INIS)

    Waste printed circuit boards (WPCB) have an inherent value because of the precious metal content. For an effective recycling of WPCB, it is essential to recover the precious metals. This paper reports a promising method to recover the precious metals. Aqua regia was used as a leachant and the ratio between metals and leachant was fixed at 1/20 (g/ml). Silver is relatively stable so the amount of about 98 wt.% of the input was recovered without an additional treatment. Palladium formed a red precipitate during dissolution, which were consisted of Pd(NH4)2Cl6. The amount precipitated was 93 wt.% of the input palladium. A liquid-liquid extraction with toluene was used to extract gold selectively. Also, dodecanethiol and sodium borohydride solution were added to make gold nanoparticles. Gold of about 97 wt.% of the input was recovered as nanoparticles which was identified with a high-resolution transmission electron microscopy through selected area electron diffraction and nearest-neighbor lattice spacing.

  2. Characterization and electrocatalytic properties of sonochemical synthesized PdAg nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Godinez-Garcia, Andres, E-mail: agodinez@qro.cinvestav.mx [Depto. Materiales, Centro de Investigacion y de Estudios Avanzados del IPN, Libramiento norponiente 2000, Fracc. Real de Juriquilla, C.P. 76230 Santiago de Queretaro, Qro. (Mexico); Perez-Robles, Juan Francisco [Depto. Materiales, Centro de Investigacion y de Estudios Avanzados del IPN, Libramiento norponiente 2000, Fracc. Real de Juriquilla, C.P. 76230 Santiago de Queretaro, Qro. (Mexico); Martinez-Tejada, Hader Vladimir [Grupo de Energia y Termodinamica, Universidad Pontificia Bolivariana, Medellin, Antioquia C.P. 050031 (Colombia); Solorza-Feria, Omar [Depto. Quimica, CINVESTAV-IPN, Av. IPN 2508, A. P. 14-740, 07360 D.F. Mexico (Mexico)

    2012-06-15

    High intensity ultrasound was used in the synthesis of PdAg nanoparticles. PdAg nanoparticles were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), scanning transmission electron microscopy (STEM) and high-resolution transmission electron microscopy (HRTEM). Catalytic properties for oxygen reduction reaction (ORR) were determined by electrochemical techniques of cyclic voltammetry (CV) and thin-film rotating disk electrode (TF-RDE). Finally the electrocatalyst was tested as a cathode in a single polymer electrolyte membrane fuel cell (PEMFC). Sonochemical synthesis (SS) decreased the overpotential required for the ORR and increased the double-layer capacitance (DLC) respect to the sodium borohydride reduction method due to a better distribution on vulcan carbon support. The electrocatalytic activity of the nanometric bimetallic electrocatalyst for the ORR in acid media showed a favorable multielectron charge transfer process (n = 4e{sup -}) to water formation. The performance of the membrane electrode assembly (MEA) prepared with dispersed PdAg/C as a cathode catalyst in a single PEMFC is lower in comparison to platinum. - Highlights: Black-Right-Pointing-Pointer Sonochemical synthesized PdAg nanoparticles supported on carbon were produced. Black-Right-Pointing-Pointer The material showed catalytic properties for the oxygen reduction reaction (ORR). Black-Right-Pointing-Pointer The ORR favored the pathway to water formation.

  3. Microwave combustion and sintering without isostatic pressure

    International Nuclear Information System (INIS)

    In recent years interest has grown rapidly in the application of microwave energy to the processing of ceramics, composites, polymers, and other materials. Advances in the understanding of microwave/materials interactions will facilitate the production of new ceramic materials with superior mechanical properties. One application of particular interest is the use of microwave energy for the mobilization of uranium for subsequent redeposition. Phase III (FY98) will focus on the microwave assisted chemical vapor infiltration tests for mobilization and redeposition of radioactive species in the mixed sludge waste. Uranium hexachloride and uranium (IV) borohydride are volatile compounds for which the chemical vapor infiltration procedure might be developed for the separation of uranium. Microwave heating characterized by an inverse temperature profile within a preformed ceramic matrix will be utilized for CVI using a carrier gas. Matrix deposition is expected to commence from the inside of the sample where the highest temperature is present. The preform matrix materials, which include aluminosilicate based ceramics and silicon carbide based ceramics, are all amenable to extreme volume reduction, densification, and vitrification. Important parameters of microwave sintering such as frequency, power requirement, soaking temperature, and holding time will be investigated to optimize process conditions for the volatilization of uranyl species using a reactive carrier gas in a microwave chamber

  4. Parametric optimization and prediction of electroless Ni-B deposition

    International Nuclear Information System (INIS)

    The alkaline borohydride-reduced bath has been used to deposit electroless nickel-boron (Ni-B) coatings on a pure (99.99%) copper substrate. The electroless Ni-B deposition per unit area has been considered as a response variable and response surface method has been used to optimize the process parameters and the response. Initially, a first order response surface model has been considered and steepest ascent method has been used to reach in the vicinity of optimal region of the response surface and subsequently, a second order response surface model with central composite design (CCD) has been used to take into account the curvature around the optimal region. The predicting response surface equation has been determined by using MATLAB software package and the optimal values of process parameters have been determined for maximum deposition per unit area. The three-dimensional surface and contour plots shows the variation Ni-B deposition with different process parameters. F-test for the predicting response surface equation confirms that the equation gives an excellent fitting to the experimentally observed data

  5. Supercritical nitrogen processing for the purification of reactive porous materials.

    Science.gov (United States)

    Stadie, Nicholas P; Callini, Elsa; Mauron, Philippe; Borgschulte, Andreas; Züttel, Andreas

    2015-01-01

    Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. Herein, nitrogen is presented as a novel supercritical drying fluid for specialized applications such as in the processing of reactive porous materials, where carbon dioxide and other fluids are not appropriate due to their higher chemical reactivity. Nitrogen exhibits similar physical properties in the near-critical region of its phase diagram as compared to carbon dioxide: a widely tunable density up to ~1 g ml(-1), modest critical pressure (3.4 MPa), and small molecular diameter of ~3.6 Å. The key to achieving a high solvation power of nitrogen is to apply a processing temperature in the range of 80-150 K, where the density of nitrogen is an order of magnitude higher than at similar pressures near ambient temperature. The detailed solvation properties of nitrogen, and especially its selectivity, across a wide range of common target species of extraction still require further investigation. Herein we describe a protocol for the supercritical nitrogen processing of porous magnesium borohydride. PMID:26066492

  6. Polyelectrolyte induced formation of silver nanoparticles in copolymer hydrogel and their application as catalyst

    International Nuclear Information System (INIS)

    Highlights: • A simple route for the in situ preparation of Ag nanoparticles has been developed. • The Ag loaded hydrogel showed catalytic activity for reduction of 4-nitrophenol. • The catalyst can be recovered by simple separation and showed good recyclability. - Abstract: A simple route for the in situ preparation of catalytically active Ag nanoparticles (NPs) in hydrogel networks has been developed. The electronegativity of the amide and carboxyl groups on the poly(acrylamide-co-acryl acid) chains caused strong binding of the Ag+ ions which made the ions distribute uniformly inside the hydrogels. When the Ag+ loaded hydrogels were immersed in NaBH4 solution, the Ag+ ions on the polymer networks were reduced to Ag NPs. The resultant hydrogel showed good catalytic activity for the reduction of a common organic pollutant, 4-nitrophenol, with sodium borohydride. A kinetic study of the catalytic reaction was carried out and a possible reason for the decline of the catalytic performance with reuse is proposed

  7. Oxygen reduction reaction catalyzed by platinum nanonetwork prepared by template free one step synthesis for polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Narayanamoorthy, B. [Department of Chemistry, Faculty of Science, Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya (SCSVMV University), Enathur, Kanchipuram 631 561 (India); Kumar, B.V.V.S. Pavan; Eswaramoorthy, M. [Nanomaterials and Catalysis Lab, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore 560 064 (India); Balaji, S., E-mail: prof.balaji13@gmail.com [Department of Chemistry, Faculty of Science, Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya (SCSVMV University), Enathur, Kanchipuram 631 561 (India)

    2014-07-01

    Highlights: • Supportless Pt nanonetwork (Pt NN) synthesized by novel template free one step method as per our earlier reported procedure. • Electrocatalytic activity of Pt NN studied taking oxygen reduction reaction in acid medium. • Kinetic and thermodynamic parameters were deduced under hydrodynamic conditions. • ORR mechanistic pathway was proposed based on kinetic rate constants. • ADT analysis found enhanced stability (5000 cycles) for Pt NN than Pt NN/VC and reported Pt/C. - Abstract: The reduction reaction of molecular oxygen (ORR) was investigated using supportless Pt nanonetwork (Pt NN) electrocatalyst in sulfuric acid medium. Pt NN was prepared by template free borohydride reduction. The transmission electron microscope images revealed a network like nano-architecture having an average cluster size of 30 nm. The electrochemical characterization of supportless and Vulcan carbon supported Pt NN (Pt NN/VC) was carried out using rotating disc and ring disc electrodes at various temperatures. Kinetic and thermodynamic parameters were estimated under hydrodynamic conditions and compared with Pt NN/VC and reported Pt/C catalysts. The accelerated durability test revealed that supportless Pt NN is quite stable for 5000 potential cycles with 22% reduction in electrochemical surface area (ECSA). While the initial limiting current density has in fact increased by 11.6%, whereas Pt NN/VC suffered nearly 55% loss in ECSA and 13% loss in limiting current density confirming an enhanced stability of supportless Pt NN morphology for ORR compared to conventional Pt/C ORR catalysts in acid medium.

  8. Mechanism for formation of NaBH4 proposed as low-pressure process for storing hydrogen in borosilicate glass–sodium solid system: a hydrogen storage material

    Indian Academy of Sciences (India)

    Aysel Kantürk Figen; Sabriye Pişkin

    2012-04-01

    The mechanism for the formation of sodium borohydride (NaBH4) was investigated for its ability to store hydrogen in the borosilicate glass–sodium (BSG–Na) solid system under low hydrogen pressure. BSG, which was prepared by melting borax with silica, was used as the starting material in the BSG–Na system that would be prepared to store hydrogen. It was observed that the mechanism for storing hydrogen in the BSG–Na solid system consisted of six steps and when the BSG–Na system was heated under a pressure of 4 atm, which was created through the use of hydrogen atmosphere, the storage of hydrogen occurred at nearly 480°C for approximate duration of 200 min, with the excellent yield (97%). In addition, the hydrogen storage capacity of the NaBH4 sample was measured using the Au–PS structure, which was designed as a mini-hydrogen cell. It was determined that the minimum amount of NaBH4 to generate the maximum volume of hydrogen gas was 12 mg/ml at 270 mV.

  9. In Vitro Structural and Functional Evaluation of Gold Nanoparticles Conjugated Antibiotics

    Science.gov (United States)

    Saha, Biswarup; Bhattacharya, Jaydeep; Mukherjee, Ananda; Ghosh, Anup Kumar; Santra, Chitta Ranjan; Dasgupta, Anjan K.; Karmakar, Parimal

    2007-12-01

    Bactericidal efficacy of gold nanoparticles conjugated with ampicillin, streptomycin and kanamycin were evaluated. Gold nanoparticles (Gnps) were conjugated with the antibiotics during the synthesis of nanoparticles utilizing the combined reducing property of antibiotics and sodium borohydride. The conjugation of nanoparticles was confirmed by dynamic light scattering (DLS) and electron microscopic (EM) studies. Such Gnps conjugated antibiotics showed greater bactericidal activity in standard agar well diffusion assay. The minimal inhibitory concentration (MIC) values of all the three antibiotics along with their Gnps conjugated forms were determined in three bacterial strains, Escherichia coli DH5α, Micrococcus luteus and Staphylococcus aureus. Among them, streptomycin and kanamycin showed significant reduction in MIC values in their Gnps conjugated form whereas; Gnps conjugated ampicillin showed slight decrement in the MIC value compared to its free form. On the other hand, all of them showed more heat stability in their Gnps conjugated forms. Thus, our findings indicated that Gnps conjugated antibiotics are more efficient and might have significant therapeutic implications.

  10. Characterization and electrocatalytic properties of sonochemical synthesized PdAg nanoparticles

    International Nuclear Information System (INIS)

    High intensity ultrasound was used in the synthesis of PdAg nanoparticles. PdAg nanoparticles were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), scanning transmission electron microscopy (STEM) and high-resolution transmission electron microscopy (HRTEM). Catalytic properties for oxygen reduction reaction (ORR) were determined by electrochemical techniques of cyclic voltammetry (CV) and thin-film rotating disk electrode (TF-RDE). Finally the electrocatalyst was tested as a cathode in a single polymer electrolyte membrane fuel cell (PEMFC). Sonochemical synthesis (SS) decreased the overpotential required for the ORR and increased the double-layer capacitance (DLC) respect to the sodium borohydride reduction method due to a better distribution on vulcan carbon support. The electrocatalytic activity of the nanometric bimetallic electrocatalyst for the ORR in acid media showed a favorable multielectron charge transfer process (n = 4e−) to water formation. The performance of the membrane electrode assembly (MEA) prepared with dispersed PdAg/C as a cathode catalyst in a single PEMFC is lower in comparison to platinum. - Highlights: ► Sonochemical synthesized PdAg nanoparticles supported on carbon were produced. ► The material showed catalytic properties for the oxygen reduction reaction (ORR). ► The ORR favored the pathway to water formation.

  11. Determination of total inorganic arsenic in potable water through spectroscopy of atomic absorption with generation of hydride

    International Nuclear Information System (INIS)

    This study developed a method for the cuantitative analysis of arsenic in potable water , through the spectrophotometric technique of atomic absorption. It used an automatic system of injection of flux for the generation of hydrides. It studied the effect produced by reducer agents, in the prereduction of arsenic in water, obtaining the best result with the use of potasium iodide 1.5% and ascorbic acid 0.25% in hydrochloric acid 3.7%, for the direct determination of total inorganic arsenic. It observed the effect produced by cadmium and selenium to the half of the concentration of arsenic, chromium, lead and silver at the same concentration, and barium at a ten times higher concentration, in the recuperation of total inorganic arsenic. It also used sodium borohydride 0.3% in sodium hydroxide 0.05% (5mL/min), for the formation of the volatile hydrides. It used hydrochloric acid 3.7% (12 mL/min) as disolution of transport; argon as inert gas, and a flame air-acetylene, for the atomization of the hydrides. This method was applied to 19 samples of potable water, and the result was no detectable for all of them. (S. Grainger)

  12. Autonomously Propelled Motors for Value-Added Product Synthesis and Purification.

    Science.gov (United States)

    Srivastava, Sarvesh K; Schmidt, Oliver G

    2016-06-27

    A proof-of-concept design for autonomous, self-propelling motors towards value-added product synthesis and separation is presented. The hybrid motor design consists of two distinct functional blocks. The first, a sodium borohydride (NaBH4 ) granule, serves both as a reaction prerequisite for the reduction of vanillin and also as a localized solid-state fuel in the reaction mixture. The second capping functional block consisting of a graphene-polymer composite serves as a hydrophobic matrix to attract the reaction product vanillyl alcohol (VA), resulting in facile separation of this edible value-added product. These autonomously propelled motors were fabricated at a length scale down to 400 μm, and once introduced in the reaction environment showed rapid bubble-propulsion followed by high-purity separation of the reaction product (VA) by the virtue of the graphene-polymer cap acting as a mesoporous sponge. The concept has excellent potential towards the synthesis/isolation of industrially important compounds, affinity-based product separation, pollutant remediation (such as heavy metal chelation/adsorption), as well as localized fuel-gradients as an alternative to external fuel dependency. PMID:27123788

  13. Fast and facile preparation of CTAB based gels and their applications in Au and Ag nanoparticles synthesis

    International Nuclear Information System (INIS)

    We have demonstrated that the gel-like mesophase of Cetyltrimethylammonium bromide (CTAB) can be synthesized by judicial adjustment of water to surfactant molar ratio (W0), without using any additional salts, gelating agents or co-surfactants. Gel formation was found to be highly dependent on the water to surfactant molar ratio (W0), with the lowest value of W0 (41.5) resulting in rapid gel formation. Environmental scanning electron microscope (ESEM) analysis revealed that the gel was comprised of interconnected cylindrical structures. The presence of hydrogen bonding in the gel-like mesophase was confirmed by Fourier Transform Infrared spectroscopy (FTIR) analysis. Rheology measurements revealed that all the gel samples were highly viscoelastic in nature. Furthermore, Au and Ag containing CTAB gels were explored as precursors for the preparation of spherical Gold (Au) and Silver (Ag) nanoparticles using Sodium borohydride (NaBH4) as reducing agent. The effects of NaBH4 concentration on the particle size and morphology of the Au and Ag nanoparticles have also been studied. - Highlights: • A facile synthesis of CTAB based gel-like mesophase is reported. • CTAB gels were obtained by adjusting water to surfactant molar ratio (W0). • FTIR analysis revealed that hydrogen bonding plays a key role in gel formation. • Au, Ag nanoparticles were synthesized by using CTAB gel and NaBH4

  14. Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors

    International Nuclear Information System (INIS)

    Luminescent quantum dots were synthesized using bacterially derived selenide (SeII−) as the precursor. Biogenic SeII− was produced by the reduction of SeIV by Veillonella atypica and compared directly against borohydride-reduced SeIV for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological SeII− formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic SeII− included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic SeII− is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, ‘green’ synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams. (paper)

  15. Preparation of spherical and cubic Fe55Co45 microstructures for studying the role of particle morphology in magnetorheological suspensions

    Science.gov (United States)

    Arief, Injamamul; Mukhopadhyay, P. K.

    2014-06-01

    Cubic and spherical Fe55Co45 alloyed microstructures were synthesized by borohydride reduction from aqueous solutions of metallic precursors, using stabilizers and polymer. Monosodium citrate, sodium acetate and PEG 6000 were utilized as electrostatic stabilizers and polymeric surface modifier. Suitable reaction conditions were maintained for synthesis of predominantly larger particles (0.7 µm to 1.2 µm), that facilitates use in magnetorheological fluids. Surface morphological studies by scanning electron microscopy revealed well shaped cubic and spherical geometry for the citrate and polymer-stabilized Fe55Co45 alloys, while the alloy compositions remained nearly the same for both. X-ray diffractions of the as-prepared and annealed samples under various temperatures showed high degree of crystallinity with increasing temperatures. Studies of D.C. magnetization of the systems reveal that the particles have a core-shell structure, with inner magnetic core having a diameter around 30 nm with a log-normal distribution. Magnetorheological studies were performed with 8 vol% suspensions of as-synthesized particles dispersed in silicone oil (viscosity 30 mPa s at 25 °C) under different magnetic fields. Detailed studies of the magnetorheological properties were studied on these systems for practical use.

  16. A comprehensive study on the effect of Ru addition to Pt electrodes for direct ethanol fuel cell

    Indian Academy of Sciences (India)

    J Datta; S Singh; S Das; N R Bandyopadhyay

    2009-12-01

    The electro-oxidation of ethanol was studied over nanosized Pt and different compositions of PtRu catalysts synthesized by the borohydride reduction method. Physicochemical characterizations of the catalyst material were made by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with EDX analysis and transmission electron microscopy (TEM). XRD patterns showed that Ru induces a contraction of the Pt lattice. EDX provided the composition of binary catalysts while TEM images indicated uniform distribution of discrete nanoparticle of the catalysts with narrow range. The electro-catalytic activities of the materials towards ethanol oxidation were investigated through electrochemical techniques, viz. cyclic voltammetry (CV), potentiodynamic polarization, chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) at room temperature. The onset potential of ethanol electro-oxidation is lowered on bimetallic PtRu catalysts compared to that on Pt alone. Of the investigated catalyst compositions the one with the highest electrocatalytic activity was found to be Pt82Ru18. This enhancement towards ethanol oxidation is explained on the basis of a structural effect and modified bi-functional mechanism.

  17. Types of oligosaccharide sulphation, depending on mucus glycoprotein source, corpus or antral, in rat stomach.

    Science.gov (United States)

    Goso, Y; Hotta, K

    1989-01-01

    Radiolabelled mucus glycoprotein was obtained from tissue and a culture medium each of the corpus and antrum of rat stomach incubated with [35S]sulphate in vitro. Gel-filtration analysis of oligosaccharides liberated by alkaline-borohydride treatment from glycoproteins indicated that 35S-labelled oligosaccharides from the corpus vary considerably with respect to chain length whereas those from antral mucus glycoprotein are composed of small oligosaccharides. Examination of the reduced radiolabelled products obtained by HNO2 cleavage of the hydrazine-treated oligosaccharides indicated sulphate esters of N-acetylglucosamine to be present at three locations on a carbohydrate unit: [35S]sulphated monosaccharide (2,5-anhydromannitol 6-sulphate), [35S]sulphated disaccharide [galactosyl(beta 1-4)-2,5-anhydromannitol 6-sulphate] and [35S]sulphated trisaccharide [fucosyl(alpha 1-2)-galactosyl(beta 1-4)-2,5-anhydromannitol 6-sulphate]. Sulphated disaccharide and trisaccharide, possibly originating from the N-acetyl-lactosamine and fucosyl-N-acetyl-lactosamine sequences respectively, were detected in the corpus, especially as large oligosaccharides, but were present in the antrum in only very small amounts. The sulphated monosaccharide, however, most probably originating from 6-sulphated N-acetylglucosamine residues at non-reducing termini, was present in all oligosaccharide fractions in both the corpus and antrum. Images Fig. 4. Fig. 7. Fig. 8. PMID:2695066

  18. Interleukin-1 induced nitric oxide inhibits sulphation of glycosaminoglycan chains in human articular chondrocytes.

    Science.gov (United States)

    Hickery, M S; Bayliss, M T

    1998-10-23

    Incubation of human articular cartilage explants with interleukin-1alpha (IL-1alpha) inhibited the rate of [35S]sulphate incorporation into glycosaminoglycan (GAG) chains concomitant with an increase in nitric oxide (NO) production. Measurement of the [35S]sulphate showed that IL-1alpha inhibited the synthesis of both keratan sulphate and chondroitin sulphate (CS) chains to a similar extent. This effect was reversed by the NO synthase inhibitor Nomega-iminoethyl-l-ornithine (l-NIO). Analysis of alkali borohydride cleaved GAG chains showed that IL-1alpha had no effect on their size. Similarly when GAG chains were coupled to xyloside the size of the GAG chains attached to the exogenous acceptor decreased but IL-1alpha had no further effect on hydrodynamic size. IL-1alpha did, however, inhibit [35S]sulphate incorporation into xyloside-linked CS chains. In both experiments l-NIO reversed the inhibitory effect on sulphation. Disaccharide analysis of the [35S]GAG chains showed that IL-1alpha preferentially inhibited sulphation of the 6-sulphated isomer and that l-NIO reversed this effect. Thus, IL-1alpha-induced NO mediates the inhibition of sulphate incorporation and alters the sulphation pattern of newly synthesised GAG chains. PMID:9795242

  19. Micro reactor integrated μ-PEM fuel cell system: a feed connector and flow field free approach

    Science.gov (United States)

    Balakrishnan, A.; Mueller, C.; Reinecke, H.

    2013-12-01

    A system level microreactor concept for hydrogen generation with Sodium Borohydride (NaBH4) is demonstrated. The uniqueness of the system is the transport and distribution feature of fuel (hydrogen) to the anode of the fuel cell without any external feed connectors and flow fields. The approach here is to use palladium film instead of feed connectors and the flow fields; palladium's property to adsorb and desorb the hydrogen at ambient and elevated condition. The proof of concept is demonstrated with a polymethyl methacrylate (PMMA) based complete system integration which includes microreactor, palladium transport layer and the self-breathing polymer electrolyte membrane (PEM) fuel cell. The hydrolysis of NaBH4 was carried out in the presence of platinum supported by nickel (NiPt). The prototype functionality is tested with NaBH4 chemical hydride. The characterization of the integrated palladium layer and fuel cell is tested with constant and switching load. The presented integrated fuel cell is observed to have a maximum power output and current of 60 mW and 280 mA respectively.

  20. Synthesis of the d,I-HM-PAO and formulation of nucleo-equipment for the obtention of 99m Tc-(d,I)-HM-PAO

    International Nuclear Information System (INIS)

    Most brain imaging radiopharmaceuticals are conventional hydrophilic compounds that are excluded from entering the normal brain by an intact blood-brain barrier (BBB). Under pathologic conditions, the barrier is disrupted and radiotracer concentrates in the leisure for positive identification. 99m Tc- hexa methyl propylene amine oxime (99m Tc-HM-PAO) is a newer-type lipophilic agent that enter the normal brain through an intact BBB. Studies with this agent offer the promise of measuring cerebral perfusion in the normal and diseased brain. In this paper we present the synthesis and Tc-99m labelling of d,I-HM-PAO. The synthesis of the ligand was carried out by condensation of two molecular equivalents of butanedione monoxime with one molecular equivalent of 1,3 propanediamine provided a bis imine intermediate, which was reduced with sodium borohydride to get the meso and d,I diastereoisomers of HM-PAO. Separation of these was achieved by fractional crystallization. 99m Tc-(d,I)HM-PAO was obtained by stannous ion reduction of Mo-99/Tc-99m generator eluate in the presence of the ligand. Complex radiochemical purity was determined by instant thin layer chromatography and paper chromatography. Finally, we obtained 99m Tc-(d,I)HM-PAO with a high radiochemical yield, in excess of 90%. However, for subsequent clinical studies the preparation has to be done a few minutes before application because our product has a low stability. (Author)

  1. Cysteine functionalized copper organosol: synthesis, characterization and catalytic application

    International Nuclear Information System (INIS)

    We herein report a facile one-pot synthesis, stabilization, redispersion and Cu-S interaction of L-cysteine and dodecanethiol (DDT) protected copper organosol in toluene from precursor copper stearate using sodium borohydride in toluene under a nitrogen atmosphere. Surface modification of the synthesized copper organosol with an amino acid L-cysteine and an alkanethiol (dodecanethiol, DDT) is accomplished by a thiolate bond between the used ligands and nanoparticle surface. The cysteine molecule binds the copper surface via a thiolate and amine linkage but not through electrostatic interaction with the carboxylate group due to the solvent polarity and dielectric medium. Fourier transform infrared (FTIR) analysis was performed to confirm the surface functionalization of the amino acid and DDT to the copper surface. Copper organosol has been characterized by optical spectroscopy (UV/vis), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). The as-synthesized particles are spherical in shape and exhibit a Mie scattering profile with an absorption maxima in the visible range. Copper nanoparticles capped by cysteine and/or DDT in non-aqueous media are found to represent an interesting catalytic approach for the synthesis of octylphenyl ether

  2. Copper Alginate-Cotton Cellulose (CACC Fibers with Excellent Antibacterial Properties

    Directory of Open Access Journals (Sweden)

    Navin Chand, Ph.D.

    2009-09-01

    Full Text Available The present work describes synthesis of copper alginate-cotton cellulose (CACC composite fibers and detailed investigation of antimicrobial action against the model bacteria E.coli. The CACC fibers were prepared by immersing cotton fibers in aqueous solution of sodium alginate, followed by ionic crosslinking of alginate chains within the cotton cellulose fibers with Cu(II ions to yield CACC composite fibers. The resulting CACC fibers were investigated for their biocidal action against E.coli, by using zone inhibition and colonies counting method. Finally, CACC fibers were reduced with sodium borohydride to yield copper nanoparticles- loaded composite fibers and investigated for biocidal action. It was found that CACC fibers possessed both, the fair mechanical strength and antibacterial action. The extent of biocidal action was found to depend upon the amount of Cu(II loaded and concentration of alginate into cotton- cellulose fibers. The fibers showed higher Cu(II release in physiological fluid as compared to distilled water. Copper alginate-cotton cellulose (CACC fibers show fair mechanical strength and release copper ions in the presence of physiological fluid and protein solution. These fibers have great potential to be used as dressing materials.

  3. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate

    Science.gov (United States)

    Jun Yin, Hong; Yang Chen, Zhao; Mei Zhao, Yong; Yang Lv, Ming; An Shi, Chun; Long Wu, Zheng; Zhang, Xin; Liu, Luo; Li Wang, Ming; Jun Xu, Hai

    2015-09-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br- and I-), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd2+ at 10-8  M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface.

  4. 2',3'-cyclic nucleotide-3'-phosphodiesterase in the central nervous system is fatty-acylated by thioester linkage.

    Science.gov (United States)

    Agrawal, H C; Sprinkle, T J; Agrawal, D

    1990-07-15

    2',3'-Cyclic nucleotide-3'-phosphodiesterase (CNP1 and CNP2 with Mr of 46,000 and 48,000, respectively) is the major enzyme of central nervous system myelin. It is associated with oligodendroglial plasma membrane and uncompacted myelin (myelin-like fraction), which are in contact with glial cytoplasm. Proteins of the myelin-like fraction were labeled with [3H]palmitic acid in brain slices from 17-day-old rats and immunoprecipitated with anti-CNP antiserum. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitated material revealed intense acylation of CNP1 and CNP2, and radioactivity was released by hydroxylamine. Palmitic acid was covalently bound to CNP because radioactivity was not removed by extraction of immunoprecipitated CNP with organic solvent or by boiling in sodium dodecyl sulfate and dithiothreitol. However, treatment of immunoprecipitated CNP with (a) hydroxylamine-released palmitohydroxamate and palmitic acid, (b) sodium borohydride-released hexadecanol, and (c) methanolic-KOH-released methyl palmitate. Synthesis, acylation, or transport of CNP was not affected by monensin or colchicine. However, acylation of CNP was inhibited 24-32% by cycloheximide. These results provide conclusive evidence that CNP1 and CNP2 are fatty acid acylated with palmitate through a thioester linkage and is posttranslationally modified sometime after synthesis. PMID:2164018

  5. Histochemical and structural analysis of mucous glycoprotein secreted by the gill of Mytilus edulis

    International Nuclear Information System (INIS)

    Studies were carried out to characterized various mucous cells in the gill filament, to ascertain structural characteristics of the secreted mucous glycoproteins, and to determine the ability of the gill epithelium to incorporate [14C]glucosamine as a precursor in the biosynthesis and secretion of mucous glycoproteins. Using histochemical staining techniques, mucous cells containing neutral and acidic mucins were found in the lateral region, whereas mucous cells containing primarily neutral or sulfated mucins were found in the postlateral region. Serotonin, but not dopamine, stimulated the mucous secretion. In tissues pretreated with [14C]glucosamine, the secreted glycoproteins contain incorporated radiolabel. Analysis by column chromatography using Bio-Gel P-2 and P-6 shows that the secretion contains two glycoprotein populations. Glycoprotein II has a molecular weight of 2.3 x 104 daltons. Upon alkaline reductive borohydride cleavage of the O-glycosidic linkages of glycoprotein I, about 70% of the radiolabel was removed from the protein. Gas chromatographic analysis of the carbohydrate composition shows that the glycoproteins contains N-acetylglucosamine (GluNAc), N-acetylgalactosamine (GalNAc), and galactose, fucose and mannose. Amino acid analysis shows that the glycoproteins are rich in serine, threonine and proline

  6. Electrocatalytic activities of alkyne-functionalized copper nanoparticles in oxygen reduction in alkaline media

    Science.gov (United States)

    Liu, Ke; Song, Yang; Chen, Shaowei

    2014-12-01

    Stable alkyne-capped copper nanoparticles were prepared by chemical reduction of copper acetate with sodium borohydride in the presence of alkyne ligands. Transmission electron microscopic measurements showed that nanoparticles were well dispersed with a diameter in the range of 4-6 nm. FTIR and photoluminescence spectroscopic measurements confirmed the successful attachment of the alkyne ligands onto the nanoparticle surface most likely forming Cu-Ctbnd interfacial bonds. XPS measurements indicated the formation of a small amount of CuO in the nanoparticles with a satellite peak where the binding energy red-shifted with increasing Cu(II) concentration. Cu2O was also detected in the nanoparticles. Similar results were observed with commercial CuO nanoparticles. Electrochemical studies showed that the as-prepared alkyne-capped copper nanoparticles exhibited apparent electrocatalytic activity in oxygen reduction in alkaline media, a performance that was markedly better than those reported earlier with poly- or single-crystalline copper electrodes; and the fraction of peroxides in the final products decreased with decreasing concentration of oxide components in the nanoparticles.

  7. In vitro studies of carbon fiber microbiosensor for dopamine neurotransmitter supported by copper-graphene oxide composite

    International Nuclear Information System (INIS)

    A composite was prepared from copper and graphene oxide (Cu-GO) by in-situ chemical reduction of a mixture containing GO and Cu(II) ions with potassium borohydride. The morphology and structure of the composite were confirmed by various physicochemical techniques. The materials were used in a tyrosinase-based microbiosensor where the enzyme is immobilized in a biocompatible matrix consisting of poly(ortho-phenylene diamine) and Cu-GO. The composite was deposited on the surface of an 8-μm thick carbon fiber microelectrode. The role of each component in the sensing layer was systematically investigated with respect to the analytical performance of the system. In its optimal configuration, the biosensor demonstrated (a) a sensitivity of 6.1 ± 3 nA mM-1 dopamine (DA), (b) a linear response to DA (with a Michaelis-Menten constant of 0.29 ± 0.03 mM), (c) good selectivity over ascorbic acid and uric acid, and (d) a high blocking capacity (112.2 ± 2 mM) for ascorbic acid. (author)

  8. Fullerene-ionic-liquid conjugates: a new class of hybrid materials with unprecedented properties.

    Science.gov (United States)

    Campisciano, Vincenzo; La Parola, Valeria; Liotta, Leonarda F; Giacalone, Francesco; Gruttadauria, Michelangelo

    2015-02-16

    A modular approach has been followed for the synthesis of a series of fullerene-ionic-liquid (IL) hybrids in which the number of IL moieties (two or twelve), anion, and cation have been varied. The combination of C60 and IL give rise to new unique properties in the conjugates such as solubility in water, which was higher than 800 mg mL(-1) in several cases. In addition, one of the C60 -IL hybrids has been employed for the immobilization of palladium nanoparticles through ion exchange followed by reduction with sodium borohydride. Surprisingly, during the reduction several carbon nanostructures were formed that comprised nano-onions and nanocages with few-layer graphene sidewalls, which have been characterized by means of thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDAX), and high-resolution transmission electron microscopy (HRTEM). Finally, the material thus obtained was successfully applied as catalyst in Suzuki and Mizoroki-Heck reactions in a concentration of just 0.2 mol %. In the former process it was recyclable for five runs with no loss in activity. PMID:25589382

  9. One-step preparation of Fe3O4/Pd@polypyrrole composites with enhanced catalytic activity and stability.

    Science.gov (United States)

    Zhang, Hui; Liu, Yang; Wu, Jie; Xin, Baifu

    2016-08-15

    Core/shell Fe3O4/Pd@polypyrrole (PPy) composites with a Fe3O4 core and a PPy shell embedding Pd nanoparticles were prepared in one-step. The diameter of highly dispersed Pd nanoparticles was as small as 2.9nm owing to coordination interaction generated between Pd(2+) ions and amino groups on PPy chains. The outer PPy shell was only 6.8nm: on one hand, the coverage was beneficial to improving the stability of resulting composites; on the other hand, the shell was thin enough to permit free contact between embedding Pd nanoparticles and reactants. Additionally, the as-prepared Fe3O4/Pd@PPy composites displayed good magnetic separation property due to incorporation of Fe3O4 nanospheres. Based on above merits, they served as suitable catalyst candidates. Their catalytic performance and reusability were evaluated by reduction of 4-nitrophenol with sodium borohydride as reducing agent. Compared with traditional Fe3O4/Pd composites, Fe3O4/Pd@PPy composites not only showed superior catalytic activity; but also exhibited much better stability in successive cycling tests. PMID:27232537

  10. Highly stable noble metal nanoparticles dispersible in biocompatible solvents: synthesis of cationic phosphonium gold nanoparticles in water and DMSO.

    Science.gov (United States)

    Ju-Nam, Yon; Abdussalam-Mohammed, Wanisa; Ojeda, Jesus J

    2016-04-12

    In this work, we report the synthesis of novel cationic phosphonium gold nanoparticles dispersible in water and dimethyl sulfoxide (DMSO) for their potential use in biomedical applications. All the cationic-functionalising ligands currently reported in the literature are ammonium-based species. Here, the synthesis and characterisation of an alternative system, based on phosphonioalkylthiosulfate zwitterions and phosphonioalkylthioacetate were carried out. We have also demonstrated that our phosphonioalkylthiosulfate zwitterions readily disproportionate into phosphonioalkylthiolates in situ during the synthesis of gold nanoparticles produced by the borohydride reduction of gold(iii) salts. The synthesis of the cationic gold nanoparticles using these phosphonium ligands was carried out in water and DMSO. UV-visible spectroscopic and TEM studies have shown that the phosphonioalkylthiolates bind to the surface of gold nanoparticles which are typically around 10 nm in diameter. The resulting cationic-functionalised gold nanoparticles are dispersible in aqueous media and in DMSO, which is the only organic solvent approved by the U.S. Food and Drug Administration (FDA) for drug carrier tests. This indicates their potential future use in biological applications. This work shows the synthesis of a new family of phosphonium-based ligands, which behave as cationic masked thiolate ligands in the functionalisation of gold nanoparticles. These highly stable colloidal cationic phosphonium gold nanoparticles dispersed in water and DMSO can offer a great opportunity for the design of novel biorecognition and drug delivery systems. PMID:26796782

  11. Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment.

    Science.gov (United States)

    Saleh, Tawfik A; Al-Shalalfeh, Mutasem M; Al-Saadi, Abdulaziz A

    2016-01-01

    Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm(-1) were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10(-12) M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands. PMID:27572919

  12. Ag recovery from copper anode slime by acid leaching at atmospheric pressure to synthesize silver nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Atefeh Khaleghi; Sattar Ghader; Dariush Afzali

    2014-01-01

    In this paper, recovery of silver from anode slime of Sarcheshmeh copper complex in Iran and subsequent synthesis of silver nanoparticles from leaching solution is investigated. Sarcheshmeh anode slime is mainly consisted of Cu, Ag, Pb and Se. Amount of Ag in the considered anode slime was 5.4%(by weight). The goal was to recover as much as possible Ag from anode slime at atmospheric pressure to synthesize Ag nanoparticles. Therefore, acid leaching was used for this purpose. The anode slime was leached with sulfuric and nitric acid from room to 90 ?C at different acid concentrations and the run which yielded the most recovery of Ag was selected for Ag nanoparticles synthesis. At this condition, Cu, Pb and Se are lea-ched as well as Ag. To separate Ag from leach solution HCl was added and silver was precipitated as AgCl which were then dissolved by ammonia solution. The Ag nanoparticles are synthesized from this solution by chemical reduction method by aid of sodium borohydride in the presence of PVP and PEG as stabiliz-ers. The synthesized Ag nanoparticles showed a peak of 394 nm in UV-vis spectrum and TEM images showed a rather uniform Ag nanoparticles of 12 nm.

  13. Pd-Au/C catalysts with different alloying degrees for ethanol oxidation in alkaline media

    International Nuclear Information System (INIS)

    High alloyed Pd-Au/C catalyst is prepared through a rate-limiting strategy in water/ethylene glycol solution. Pd/C and low alloyed Pd-Au/C catalysts are prepared with trisodium citrate and sodium borohydride as stabilizing and reducing agents, respectively. Transmission electron microscopy (TEM) shows that the synthesized Pd(Au) particles are well dispersed on the catalysts. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) show that the high alloyed Pd-Au/C catalyst presents a relatively homogenous structure while the low alloyed Pd-Au/C catalyst presents a Pd-rich shell/Au-rich core structure. Electrochemical characterization shows that the low alloyed Pd-Au/C catalyst exhibits the best catalytic activity for ethanol oxidation reaction (EOR) in alkaline media, which could be attributed to its relatively large exposed Pd surface area as compared with the high alloyed Pd-Au/C catalyst due to its Pd-rich shell structure and its enhanced adsorption of OHads as compared with Pd/C catalyst due to its core-shell structure

  14. Enhanced Methanol Tolerance of Highly Pd rich Pd-Pt Cathode Electrocatalysts in Direct Methanol Fuel Cells

    International Nuclear Information System (INIS)

    Methanol crossover critically restricts the practical application of direct methanol fuel cells (DMFCs). To resolve this crucial difficulty from the standpoint of electrocatalysis, an electrode material having high activity for the oxygen reduction reaction and low activity for the methanol oxidation reaction compared to widely used Pt-based electrodes is needed for DMFC cathodes. In this research carbon-supported Pd-rich Pd–Pt bimetallic nanoparticle electrocatalysts with 60 wt.% metal content were prepared for this purpose by sodium borohydride reduction of metal chlorides. The physical features of the prepared nanoparticles were investigated by transmission electron microscopy, energy dispersive X-ray spectroscopy, atomic absorption spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption near edge spectroscopy. Methanol tolerance was tested by means of rotating disk electrode (RDE) voltammetry using oxygen-saturated methanol-containing electrolyte solutions as the anode fuel for DMFC unit cell performance tests. In the RDE measurements, Pd-rich electrocatalysts (carbon-supported Pd19Pt1 nanoparticles) showed excellent methanol tolerance compared with Pd-free Pt electrocatalyst. When Pd19Pt1 nanoparticles were used as a DMFC cathode catalyst, unit cell performance tests showed that the i-V curves of the Pd19Pt1 electrocatalyst decreased slightly with increasing methanol concentration, while that of the Pt electrocatalyst decreased rapidly. The results in a liquid-feed DMFC unit cell test were in good agreement with the methanol tolerant characteristics identified in the RDE measurements

  15. Performance evaluation of direct borohydride–hydrogen peroxide fuel cells with electrocatalysts supported on multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    The performance of direct borohydride–hydrogen peroxide fuel cells with electrocatalysts supported on multiwalled carbon nanotubes is evaluated under various conditions. Electrocatalysts are reduced on multiwalled carbon nanotubes by NaH2PO2 and electrodes are investigated using scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and fuel cell testing. The maximum power density decreases with increasing NaBH4 concentration, likely owing to increases in NaBH4 decomposition and crossover rates and to production of increasing amounts of NaBO2. In contrast, the maximum power density increases with increasing H2O2 concentration, likely owing to increases in reactant concentrations. Moreover, increased operating temperatures improve decomposition and electrochemical reaction rates. A thin membrane increases fuel crossover, whereas a thick membrane decreases the maximum power density; consequently, the Nafion 212 membrane is the optimal thickness for use in fuel cells such as those studied here. Under selected conditions, the maximum power density is 101.9 mW/cm2. As operation time increases, fuel cell performance is degraded by oxidation and Na deposition. - Highlights: • Maximum power density decreases as NaBH4 (sodium borohydride) concentration increases. • Maximum power density increases as H2O2 (hydrogen peroxide) concentration increases. • High operating temperatures cause fast electrochemical and decomposition reactions. • Nafion 212 is the most suitable membrane owing to its thickness. • Fuel cell performance decreases owing to oxidation and Na deposition

  16. Topological disposition of the sequences -QRKIVE- and -KETYY in native (Na sup + + K sup + )-ATPase

    Energy Technology Data Exchange (ETDEWEB)

    Bayer, R. (Univ. of California, San Diego, La Jolla (USA))

    1990-03-06

    The dispositions with respect to the plane of the membrane of lysine-905 in the internal sequence -EQRKIVE- and of lysine-1012 in the carboxy-terminal sequence -RRPGGWVEKETYY of the {alpha}-polypeptide of sodium and potassium ion activated adenosinetriphosphatase have been determined. These lysines are found in peptides released from the intact {alpha}-polypeptide by the extracellular protease from Staphylococcus aureus strain V8 and by trypsin, respectively. Synthetic peptides containing terminal sequences of these were used to prepare polyclonal antibodies, which were then used to prepare immunoadsorbents directed against the respective peptides. Sealed, right-side-out membrane vesicles containing native (Na{sup +} + K{sup +})-ATPase were labeled with pyridoxal phosphate and sodium ({sup 3}H)borohydride in the absence or presence of saponin. The labeled {alpha}-polypeptide was isolated from these vesicles and digested with appropriate proteases. The incorporation of radioactivity into the peptides binding to the immunoadsorbent directed against the sequence pyrERXIVE increased 3-fold int the presence of saponin as a result of the increased accessibility of this portion of the protein to the reagent when the vesicles were breached by saponin; hence, this sequence is located on the cytoplasmic face of the membrane. It was inferred that the carboxy-terminal sequence -KETYY is on the extracytoplasmic face since the incorporation of radioactivity into peptides binding to the immunoadsorbent directed against the sequence -ETYY did not change when the vesicles were breached with saponin.

  17. Ligand-optimized electroless synthesis of silver nanotubes and their activity in the reduction of 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Muench, Falk; Rauber, Markus; Stegmann, Christian; Lauterbach, Stefan; Kunz, Ulrike; Kleebe, Hans-Joachim; Ensinger, Wolfgang, E-mail: muench@ca.tu-darmstadt.de [Department of Materials and Geoscience, Technische Universitaet Darmstadt, Petersenstrasse 23, 64287 Darmstadt (Germany)

    2011-10-14

    A facile electroless plating procedure for the controlled synthesis of nanoscale silver thin films and derived structures such as silver nanotubes was developed and the products were characterized by SEM, TEM and EDS. The highly stable plating baths consist of AgNO{sub 3} as the metal source, a suitable ligand and tartrate as an environmentally benign reducing agent. Next to the variation of the coordinative environment of the oxidizing component, the influence of the pH value was evaluated. These two governing factors strongly affect the plating rate and the morphology of the developing silver nanoparticle films and can be used to adapt the reaction to synthetic demands. The refined electroless deposition allows the fabrication of homogeneous high aspect-ratio nanotubes in ion track etched polycarbonate. Template-embedded metal nanotubes can be interpreted as parallelled microreactors. Following this concept, both the silver nanotubes and spongy gold nanotubes obtained by the use of the silver structures as sacrificial templates were applied in the reduction of 4-nitrophenol by sodium borohydride, proving to be extraordinarily effective catalysts.

  18. Ligand-optimized electroless synthesis of silver nanotubes and their activity in the reduction of 4-nitrophenol

    International Nuclear Information System (INIS)

    A facile electroless plating procedure for the controlled synthesis of nanoscale silver thin films and derived structures such as silver nanotubes was developed and the products were characterized by SEM, TEM and EDS. The highly stable plating baths consist of AgNO3 as the metal source, a suitable ligand and tartrate as an environmentally benign reducing agent. Next to the variation of the coordinative environment of the oxidizing component, the influence of the pH value was evaluated. These two governing factors strongly affect the plating rate and the morphology of the developing silver nanoparticle films and can be used to adapt the reaction to synthetic demands. The refined electroless deposition allows the fabrication of homogeneous high aspect-ratio nanotubes in ion track etched polycarbonate. Template-embedded metal nanotubes can be interpreted as parallelled microreactors. Following this concept, both the silver nanotubes and spongy gold nanotubes obtained by the use of the silver structures as sacrificial templates were applied in the reduction of 4-nitrophenol by sodium borohydride, proving to be extraordinarily effective catalysts.

  19. Ligand-optimized electroless synthesis of silver nanotubes and their activity in the reduction of 4-nitrophenol

    Science.gov (United States)

    Muench, Falk; Rauber, Markus; Stegmann, Christian; Lauterbach, Stefan; Kunz, Ulrike; Kleebe, Hans-Joachim; Ensinger, Wolfgang

    2011-10-01

    A facile electroless plating procedure for the controlled synthesis of nanoscale silver thin films and derived structures such as silver nanotubes was developed and the products were characterized by SEM, TEM and EDS. The highly stable plating baths consist of AgNO3 as the metal source, a suitable ligand and tartrate as an environmentally benign reducing agent. Next to the variation of the coordinative environment of the oxidizing component, the influence of the pH value was evaluated. These two governing factors strongly affect the plating rate and the morphology of the developing silver nanoparticle films and can be used to adapt the reaction to synthetic demands. The refined electroless deposition allows the fabrication of homogeneous high aspect-ratio nanotubes in ion track etched polycarbonate. Template-embedded metal nanotubes can be interpreted as parallelled microreactors. Following this concept, both the silver nanotubes and spongy gold nanotubes obtained by the use of the silver structures as sacrificial templates were applied in the reduction of 4-nitrophenol by sodium borohydride, proving to be extraordinarily effective catalysts.

  20. Comparison of the reactions induced by ultrasound and gamma rays in aqueous lactose solutions

    International Nuclear Information System (INIS)

    The products obtained in aerated aqueous lactose solutions after irradiation with ultrasound and gamma rays were compared. The dose rate of gamma irradiation equivalent to the effect of ultrasound in our experiments was determined to be 1.384 kGy h-1 using the Fricke dosimeter. Separation and identification of the products were performed by gas chromatography-mass spectrometry. Three methods for the derivation of products were used: trimethylsilylation of the OH-groups; methoximation of the carbonyl groups followed by trimethylsilylation of the OH-groups; and reduction of the carbonyl and carboxyl groups to alcohols by sodium borohydride and sodium borodeuteride. The formation of products for both types of irradiation was identical, showing only minor deviations in the yield. The main reaction was oxidative splitting of the glucosidic bond, resulting in the formation of galactonic acid, glucose and galactose. Hexoculoses, gluconic acid, hexulosonic acids and glucuronic acid were detected as secondary products still containing the intact monosaccharide units. In addition, oxidation products with three to five carbon atoms were observed. The main product still containing 12 carbon atoms was lactobionic acid. (author)