WorldWideScience

Sample records for borohydrides

  1. Novel Ammonium Metal Borohydrides

    DEFF Research Database (Denmark)

    Grinderslev, Jakob; Jepsen, Lars Haahr; Cerny, Radovan

    halide-free ammonium metal borohydrides is presented, which have the chemical compositions (NH4)xM(BH4)n+x. The ammonium metal borohydrides are synthesized by cryomilling of NH4BH4 – M(BH4)n (M = Li, Na, K, Mg, Sr, Y, Mn, La, Gd) in different ratios. A new range of ammonium metal borohydrides is formed...

  2. Metal borohydrides and derivatives

    DEFF Research Database (Denmark)

    Paskevicius, Mark; Haarh Jepsen, Lars; Schouwink, Pascal

    2017-01-01

    review new synthetic strategies along with structural, physical and chemical properties for metal borohydrides, revealing a number of new trends correlating composition, structure, bonding and thermal properties. These new trends provide general knowledge and may contribute to the design and discovery......A wide variety of metal borohydrides, MBH4, have been discovered and characterized during the past decade, revealing an extremely rich chemistry including fascinating structural flexibility and a wide range of compositions and physical properties. Metal borohydrides receive increasing interest...... major classes of metal borohydride derivatives have also been discovered: anion-substituted compounds where the complex borohydride anion, BH4 -, is replaced by another anion, i.e. a halide or amide ion; and metal borohydrides modified with neutral molecules, such as NH3, NH3BH3, N2H4, etc. Here, we...

  3. Novel Ammonium Metal Borohydrides

    DEFF Research Database (Denmark)

    Grinderslev, Jakob; Jepsen, Lars Haahr; Cerny, Radovan

    , it cannot store hydrogen reversibly. Recently, the first ammonium metal borohydride, NH4Ca(BH4)3 was published, which may be considered as substitution of K+ by NH4+ in KCa(BH4)3, due to the similar sizes of NH4+ and K+[1]. This compound successfully stabilizes NH4BH4. In the present work, a series of novel...... halide-free ammonium metal borohydrides is presented, which have the chemical compositions (NH4)xM(BH4)n+x. The ammonium metal borohydrides are synthesized by cryomilling of NH4BH4 – M(BH4)n (M = Li, Na, K, Mg, Sr, Y, Mn, La, Gd) in different ratios. A new range of ammonium metal borohydrides is formed......, and the crystal structures and thermal decompositions are investigated. Mixtures of NH4BH4 - NaBH4 do not react, while solid solutions, K1-x(NH4)xBH4, are formed for NH4BH4 - KBH4. For the other composites, novel ammonium metal borohydrides are formed. Several of these structures have been solved from high...

  4. Tetramethylammonium borohydride from powder data

    Directory of Open Access Journals (Sweden)

    Tomasz Jaroń

    2011-08-01

    Full Text Available In the crystal structure of the title compound, C4H12N+·BH4−, the tetramethylammonium cations are situated on special positions with site symmetry overline{4}m2. The borohydride anions are situated on special positions with 4mm site symmetry and show rotational disorder around the fourfold axis.

  5. Ballmilling of metal borohydrides for hydrogen storage

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    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’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, no clear sign...

  6. 40 CFR 721.1878 - Alkali metal alkyl borohydride (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal alkyl borohydride... Specific Chemical Substances § 721.1878 Alkali metal alkyl borohydride (generic). (a) Chemical substance... alkali metal alkyl borohydride (PMN P-00-1089) is subject to reporting under this section for the...

  7. New borohydride anion B6H7-

    International Nuclear Information System (INIS)

    Kuznetsov, I.Yu.; Vinitskij, D.M.; Solntsev, K.A.

    1985-01-01

    The [Ni(Bipy) 3 ] (B 6 H 7 ) 2 , (Ph 4 P)B 6 H 7 , [Ni(Phen) 3 ](B 6 H 7 ) 2 crystals (where Bipy = bipyridine, Phen = phenathroline, Ph = phenyl) are obtained via the exchange reaction with a subsequent recrystallization from aqua-acetonic and acetonic solutions. The structure is studied of a new borohydride anion B 6 H 7 - possessing a four-valence bond unique for polyhedral borohydride anions. A triangular face of boride skeleton coordinating a hydrogen atom is considerably larger than other faces, and the electron density on this hydrogen atom is evidently much higher than at the end hydride hydrogen atoms. The trend of B 6 H 7 - anion to form statistically disordered structurs testifies to a rather slight effect of the seventh hydrogen atom position on the structure pattern of the ionic crystal lattice

  8. Solid Aluminum Borohydrides for Prospective Hydrogen Storage.

    Science.gov (United States)

    Dovgaliuk, Iurii; Safin, Damir A; Tumanov, Nikolay A; Morelle, Fabrice; Moulai, Adel; Černý, Radovan; Łodziana, Zbigniew; Devillers, Michel; Filinchuk, Yaroslav

    2017-12-08

    Metal borohydrides are intensively researched as high-capacity hydrogen storage materials. Aluminum is a cheap, light, and abundant element and Al 3+ can serve as a template for reversible dehydrogenation. However, Al(BH 4 ) 3 , containing 16.9 wt % of hydrogen, has a low boiling point, is explosive on air and has poor storage stability. A new family of mixed-cation borohydrides M[Al(BH 4 ) 4 ], which are all solid under ambient conditions, show diverse thermal decomposition behaviors: Al(BH 4 ) 3 is released for M=Li + or Na + , whereas heavier derivatives evolve hydrogen and diborane. NH 4 [Al(BH 4 ) 4 ], containing both protic and hydridic hydrogen, has the lowest decomposition temperature of 35 °C and yields Al(BH 4 ) 3 ⋅NHBH and hydrogen. The decomposition temperatures, correlated with the cations' ionic potential, show that M[Al(BH 4 ) 4 ] species are in the most practical stability window. This family of solids, with convenient and versatile properties, puts aluminum borohydride chemistry in the mainstream of hydrogen storage research, for example, for the development of reactive hydride composites with increased hydrogen content. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. hydrogel membrane as electrolyte for direct borohydride fuel cells

    Indian Academy of Sciences (India)

    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 ...

  10. Chemical nickel plating in tartrate solutions with borohydride reducing agent

    International Nuclear Information System (INIS)

    Plokhov, V.A.

    1986-01-01

    The authors investigate the influence of various factors on the rate of chemical nickel plating in strongly alkaline tartrate solutions with a borohydride reducing agent. After 30 min of the process of nickel plating, the final concentration of sodium borohydride decreases to 0.26 g/liter, leading to stoppage of the process. The nickel plating process can be intensified by increasing the concentration of sodium hydroxide in the solution, suppressing hydrolysis of borohydride, and also by introducing additives which suppress hydrolysis of borohydride. For chemical deposition of nickel-boron coatings from tartrate solutions the authors recommend the following composition (g/liter): nickel chloride 15-25, Rochelle salt 450-550, sodium hydroxide 140-160, sodium borohydride 0.8-1.0, thallium nitrate 0.003-0.008. The process temperature is 92-95 C, and the deposition rate is 4-6 um/h

  11. Investigation of the use of sodium borohydride for fuel cells

    OpenAIRE

    Merino Jimenez, Irene

    2013-01-01

    The use of NaBH4 for fuel cells offers a promising alternative to incumbent electrical power generation technologies. The predicted high energy density (9.3 kW h kg-1) of the direct borohydride fuel cell (DBFC) and its capacity to release 8e- per molecule converts it to a potential substitute for the H2/O2 system. Sodium borohydride, with 10.6 wt. % hydrogen content, can also generate H2 gas to be fed into a traditional H2/O2 fuel cell in an indirect borohydride fuel cell (IBFC). However, the...

  12. High pressure phases of alkali ternary borohydrides

    Science.gov (United States)

    Kumar, Ravhi; Cornelius, Andrew

    2007-03-01

    Insitu synchrotron x-ray diffraction experiments were carried out on MBH4 (M = K and Rb) borohydrides at high pressures up to 26 GPa using diamond anvil cells. KBH4 undergoes a structural transition at 4 GPa to a tetragonal phase from cubic and then to an orthorhombic phase around 7 GPa which are very similar to NaBH4 investigated earlier [1]. However, RbBH4 shows, a direct transition from the ambient cubic to an orthorhombic phase at 2.9 GPa, followed by a monoclinic phase at 8 GPa. Complementary high pressure Raman experiments, support the transitions observed in the diffraction experiments. The results will be presented in detail. [1]. Ravhi S. Kumar and Andrew L. Cornelius, Appl.Phys.Lett., 87,261916 (2005) This work is supported in part by the U.S. Department of Energy (DOE) under Award Number DE-FG36 05GO85028. HPCAT is supported by DOE-BES, DOE-NNSA,NSF, and the W.M. Keck Foundation.

  13. On the purity assessment of solid sodium borohydride

    Science.gov (United States)

    Botasini, Santiago; Méndez, Eduardo

    2012-01-01

    Since sodium borohydride has become extensively used as chemical hydrogen storage material in fuel cells, many techniques have been proposed to assess the purity of this substance. However, all of them are developed in aqueous media, where the reagent is unstable. In addition, its hygroscopic nature was difficults in any attempt to make precise quantifications. The present work compares three different methods, namely, voltammetric, titrimetric, and Fourier transformed infrared spectroscopy (FTIR) in order to assess the purity of sodium borohydride, using an expired and a new sodium borohydride samples as references. Our results show that only the FTIR measurements provide a simple and semi-quantitative means to assess the purity of sodium borohydride due to the fact that it is the only one that measures the sample in the solid state. A comparison between the experimental data and theoretical calculation reveals the identification of the absorption bands at 1437 cm-1 of sodium metaborate and 2291 cm-1 of sodium borohydride which represent a good fingerprint for the qualitative assessment of the sample quality.

  14. Economical Aspects of Sodium Borohydride for Hydrogen Storage

    International Nuclear Information System (INIS)

    Ture, I. Engin; Tabakoglu, F. Oznur; Kurtulus, Gulbahar

    2006-01-01

    Hydrogen is the best fuel among others, which can minimize the cause to global warming. Turkey has an important location with respect to hydrogen energy applications. Moreover, Turkey has 72.2% of the world's total boron reserves. Sodium borohydride (NaBH 4 ) which can be produced from borax has high hydrogen storage capacity. Hence, it is important for Turkey to lead studies about sodium borohydride to make it one of the most feasible hydrogen storage methods. In this paper an approximate process cost analysis of a NaBH 4 -H 2 system is given, starting with NaBH 4 production till recycling of it. It is found that, the usage of NaBH 4 as hydrogen storage material is relatively an expensive method but after improving reactions and by-product removal in the system and reducing the energy and reactant costs, sodium borohydride is one of the best candidates among hydrogen storage technologies. (authors)

  15. 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)

  16. Synthesis of halide- and solvent free metal borohydrides

    DEFF Research Database (Denmark)

    Grinderslev, Jakob; Møller, Kasper Trans; Richter, Bo

    have challenges due to their high desorption kinetics and limited reversibility at moderate conditions.[2],[3],[4] In this work, we present a new approach to synthesize halide- and solvent free metal borohydrides starting from the respective metal hydride. The synthetic strategy ensures that no metal...... to the metal. Hence, the powdered M(BH4)3∙DMS is heated to 140 °C for 4 hours to obtain pure M(BH4)3. The rare-earth metal borohydrides have been investigated by infrared spectroscopy and thermal analysis (TGA-DSC-MS). Furthermore, the structural trends are investigated by synchrotron radiation powder X...

  17. Synthesis of borohydrides of rare earth metals by mechanic-chemical methods

    International Nuclear Information System (INIS)

    Gafurov, B.A.; Nasrulloeva, D.Kh.; Khakyorov, I.Z.; Saidov, V.Ya.

    2010-01-01

    Present article is devoted to synthesis of borohydrides of rare earth metals by mechanic-chemical methods. The borohydrides of rare earth metals were obtained by means of mechanic-chemical methods. Physicochemical properties of obtained lanthanoid borohydrides were studied by means of X-ray phase analysis.

  18. Magnesium Borohydride: From Hydrogen Storage to Magnesium Battery

    OpenAIRE

    Mohtadi, Rana; Matsui, Masaki; Arthur, Timothy S.; Hwang, Son-Jong

    2012-01-01

    Beyond hydrogen storage: The first example of reversible magnesium deposition/stripping onto/from an inorganic salt was seen for a magnesium borohydride electrolyte. High coulombic efficiency of up to 94 % was achieved in dimethoxyethane solvent. This Mg(BH_4)_2 electrolyte was utilized in a rechargeable magnesium battery.

  19. Sodium borohydride reduction of aromatic carboxylic acids via ...

    Indian Academy of Sciences (India)

    Unknown

    selective reductions of aldehydes and ketones to the corresponding alcohols is well known.1 The reaction is normally carried out at ≈ 25°C or at reflux tempe- rature using ethanol or methanol as solvent. Although, theoretically, one equivalent of sodium borohydride provides four equivalents of hydride, however, a.

  20. hydrogel membrane as electrolyte for direct borohydride fuel cells

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 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 gold- plated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium boro- hydride as fuel and ...

  1. Metal Borohydrides synthesized from metal borides and metal hydrides

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    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...... 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 were...

  2. 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.

  3. Development of an on-board H2 storage and recovery system based on lithium borohydride.

    Science.gov (United States)

    2014-02-28

    Alkali metal borohydrides based on sodium and lithium, NaBH4 and LiBH4, have been evaluated as a potential hydrogen storage and recovery system for on-board vehicle use. The borohydride salts could be dissolved in water, followed by a hydrolytic reac...

  4. 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)

  5. Shielding efficiency of metal hydrides and borohydrides in fusion reactors

    DEFF Research Database (Denmark)

    Singh, Vishvanath P.; Badiger, Nagappa M.; Gerward, Leif

    2016-01-01

    at energies 0.015 MeV to15 MeV, and for penetration depths up to 40 mean free paths. Fast-neutron shielding efficiency has been characterized by the effective neutron removal cross-section. It is shown that ZrH2 and VH2 are very good shielding materials for gamma rays and fast neutrons due to their suitable......Mass attenuation coefficients, mean free paths and exposure buildup factors have been used to characterize the shielding efficiency of metal hydrides and borohydrides, with high density of hydrogen. Gamma ray exposure buildup factors were computed using five-parameter geometric progression fitting...... combination of low-and high-Z elements. The present work should be useful for the selection and design of blankets and shielding, and for dose evaluation for components in fusion reactors....

  6. Recent Progress in Metal Borohydrides for Hydrogen Storage

    Directory of Open Access Journals (Sweden)

    Craig M. Jensen

    2011-01-01

    Full Text Available 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(BH4n (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(BH4n, 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.

  7. 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

    Hydrogen dynamics in crystalline calcium borohydride can be initiated by long-range diffusion or localized motion such as rotations, librations, and vibrations. Herein, the rotational and translational diffusion were studied by quasielastic neutron scattering (QENS) by using two instruments...

  8. Electrocatalysis of borohydride oxidation: a review of density functional theory approach combined with experimental validation

    Science.gov (United States)

    Sison Escaño, Mary Clare; Lacdao Arevalo, Ryan; Gyenge, Elod; Kasai, Hideaki

    2014-09-01

    The electrocatalysis of borohydride oxidation is a complex, up-to-eight-electron transfer process, which is essential for development of efficient direct borohydride fuel cells. Here we review the progress achieved by density functional theory (DFT) calculations in explaining the adsorption of BH4- on various catalyst surfaces, with implications for electrocatalyst screening and selection. Wherever possible, we correlate the theoretical predictions with experimental findings, in order to validate the proposed models and to identify potential directions for further advancements.

  9. The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides.

    Science.gov (United States)

    Černý, Radovan; Schouwink, Pascal

    2015-12-01

    The crystal structures of inorganic homoleptic metal borohydrides are analysed with respect to their structural prototypes found amongst metal oxides in the inorganic databases such as Pearson's Crystal Data [Villars & Cenzual (2015). Pearson's Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2014/2015, ASM International, Materials Park, Ohio, USA]. The coordination polyhedra around the cations and the borohydride anion are determined, and constitute the basis of the structural systematics underlying metal borohydride chemistry in various frameworks and variants of ionic packing, including complex anions and the packing of neutral molecules in the crystal. Underlying nets are determined by topology analysis using the program TOPOS [Blatov (2006). IUCr CompComm. Newsl. 7, 4-38]. It is found that the Pauling rules for ionic crystals apply to all non-molecular borohydride crystal structures, and that the latter can often be derived by simple deformation of the close-packed anionic lattices c.c.p. and h.c.p., by partially removing anions and filling tetrahedral or octahedral sites. The deviation from an ideal close packing is facilitated in metal borohydrides with respect to the oxide due to geometrical and electronic considerations of the BH4(-) anion (tetrahedral shape, polarizability). This review on crystal chemistry of borohydrides and their similarity to oxides is a contribution which should serve materials engineers as a roadmap to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

  10. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Influence of the concentration of borohydride towards hydrogen production and escape for borohydride oxidation reaction on Pt and Au electrodes - experimental and modelling insights

    Science.gov (United States)

    Olu, Pierre-Yves; Bonnefont, Antoine; Braesch, Guillaume; Martin, Vincent; Savinova, Elena R.; Chatenet, Marian

    2018-01-01

    The Borohydride Oxidation Reaction (BOR), the anode reaction in a Direct borohydride fuel cell (DBFC), is complex and still poorly understood, which impedes the development and deployment of the DBFC technology. In particular, no practical electrocatalyst is capable to prevent gaseous hydrogen generation and escape from its anode upon operation, which lowers the fuel-efficiency of the DBFC and raises safety issues in operation. The nature of the anode electrocatalysts strongly influences the hydrogen escape characteristics of the DBFC, which demonstrates how important it is to isolate the BOR mechanism in conditions relevant to DBFC operation. In this paper, from a selected literature review and BOR experiments performed in differential electrochemical mass spectrometry (DEMS) in a wide range of NaBH4 concentration (5-500 mM), a microkinetic model of the BOR for both Pt and Au surfaces is proposed; this model takes into account the hydrogen generation and escape.

  12. 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.

  13. Volcano Plot for Bimetallic Catalysts in Hydrogen Generation by Hydrolysis of Sodium Borohydride

    Science.gov (United States)

    Koska, Anais; Toshikj, Nikola; Hoett, Sandra; Bernaud, Laurent; Demirci, Umit B.

    2017-01-01

    In the field of "hydrogen energy", sodium borohydride (NaBH[subscript 4]) is a potential hydrogen carrier able to release H[subscript 2] by hydrolysis in the presence of a metal catalyst. Our laboratory experiment focuses on this. It is intended for thirdyear undergraduate students in order to have hands-on laboratory experience through…

  14. First principles mechanistic study of borohydride oxidation over the Pt(1 1 1) surface

    International Nuclear Information System (INIS)

    Rostamikia, Gholamreza; Janik, Michael J.

    2010-01-01

    The mechanism of borohydride oxidation and the competing hydrolysis reaction are examined over Pt(1 1 1) using density functional theory (DFT) methods. Adsorption of BH 4 - over Au(1 1 1) and Pt(1 1 1) is examined. Adsorption over Pt(1 1 1) is dissociative and extremely exothermic at potentials of interest, leading to a high surface coverage of H * for which gaseous hydrogen evolution is competitive with oxidation. Elementary surface reactions oxidizing B-containing intermediates are favorable over Pt(1 1 1) at -0.85 V (SHE), consistent with experimental voltammetry results in the literature. The energetics of the initial adsorption step dictate the activity limitation of gold anodes and the selectivity limitation of platinum electrodes. This adsorption energy can be rapidly calculated with DFT methods, enabling screening of pure metals, alloys, poisons, and promoters to optimize borohydride oxidation catalyst design.

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

    OpenAIRE

    Liu, Cheng-Hong; Chen, Bing-Hung

    2015-01-01

    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...

  16. Tailoring the properties of ammine metal borohydrides for solid-state hydrogen storage.

    Science.gov (United States)

    Jepsen, Lars H; Ley, Morten B; Filinchuk, Yaroslav; Besenbacher, Flemming; Jensen, Torben R

    2015-04-24

    A series of halide-free ammine manganese borohydrides, Mn(BH4 )2 ⋅nNH3 , n=1, 2, 3, and 6, a new bimetallic compound Li2 Mn(BH4 )4 ⋅6NH3 , and the first ammine metal borohydride solid solution Mg1-x Mnx (BH4 )2 ⋅6NH3 are presented. Four new crystal structures have been determined by synchrotron radiation powder X-ray diffraction and the thermal decomposition is systematically investigated for all the new compounds. The solid-gas reaction between Mn(BH4 )2 and NH3 provides Mn(BH4 )2 ⋅6NH3 . The number of NH3 per Mn has been varied by mechanochemical treatment of Mn(BH4 )2 ⋅6NH3 -Mn(BH4 )2 mixtures giving rise to increased hydrogen purity for n/m≤1 for M(BH4 )m ⋅nNH3 . The structures of Mg(BH4 )2 ⋅3NH3 and Li2 Mg(BH4 )4 ⋅6NH3 have been revisited and new structural models are presented. Finally, we demonstrate that ammonia destabilizes metal borohydrides with low electronegativity of the metal (χp ∼1.6) are generally stabilized. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Derivatization of organometal(loid) species by sodium borohydride problems and solutions.

    Science.gov (United States)

    Grüter, U M; Hitzke, M; Kresimon, J; Hirner, A V

    2001-12-14

    Like other derivatization techniques, hydride generation is a chemical reaction that produces side-reactions leading to analytical problems. Demethylation of dimethylarsinic acid was observed to be dependent upon the pH level of the hydride generation reaction mixture. If the reaction mixture was acidic, then in addition to (CH3)2AsH, the monomethyl arsenic hydride [(CH3)AsH2] could be detected. Demethylation and also the formation of an unidentified arsenic species were noted when trimethyl arsonic oxide was used as derivatization educt. All of these effects depend on the pH level of the hydride generation mixture. We observed significant levels of organometal(loid) species of elements such as Ge, As, Sn, Sb, Hg and Bi in blank hydride generation mixtures. The organometal(loid) contamination was irreproducible even during I day using a single solution of sodium borohydride in deionized water. We concluded that the organometal(loid) contamination arises directly from the derivatization agent, sodium borohydride, itself. Use of helium purging and various adsorptive materials to decontaminate the sodium borohydride solution prior to analysis did not result in a significant decrease in organometal(loid) contamination levels. Use of a palladium-cluster stabilised with 1,10-phenanthrolin as alternative hydride generation derivatization agent was not found to be suitable, since reaction yields were poor and transmethylation reactions were noted.

  18. A direct borohydride fuel cell with a polymer fiber membrane and non-noble metal catalysts

    OpenAIRE

    Yang, Xiaodong; Liu, Yongning; Li, Sai; Wei, Xiaozhu; Wang, Li; Chen, Yuanzhen

    2012-01-01

    Polymer electrolyte membranes (PEM) and Pt-based catalysts are two crucial components which determine the properties and price of fuel cells. Even though, PEM faces problem of fuel crossover in liquid fuel cells such as direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC), which lowers power output greatly. Here, we report a DBFC in which a polymer fiber membrane (PFM) was used, and metal oxides, such as LaNiO3 and MnO2, were used as cathode catalysts, meanwhile CoO was us...

  19. Synthesis, structure and properties of Al-based borohydrides for hydrogen storage

    OpenAIRE

    Dovgaliuk, Iurii

    2015-01-01

    This thesis is dedicated to chemistry and hydrogen storage properties of novel complex hydrides. The main efforts were focused on synthesis and characterization of new Al-based borohydrides and amidoboranes. Somewhat different investigation on the hydrolysis of KBH4 in the atmosphere of CO2 was also performed. The series of mixed-cation M[Al(BH4)4] (M = Li+, Na+, K+, NH4+, Rb+, Cs+) were successfully obtained by a reaction of the corresponding MBH4 with Al(BH4)3. This method provides a high t...

  20. A Self-Supported Direct Borohydride-Hydrogen Peroxide Fuel Cell System

    Directory of Open Access Journals (Sweden)

    Ashok K. Shukla

    2009-04-01

    Full Text Available A self-supported direct borohydride-hydrogen peroxide fuel cell system with internal manifolds and an auxiliary control unit is reported. The system, while operating under ambient conditions, delivers a peak power of 40 W with about 2 W to run the auxiliary control unit. A critical cause and effect analysis, on the data for single cells and stack, suggests the optimum concentrations of fuel and oxidant to be 8 wt. % NaBH4 and 2 M H2O2, respectively in extending the operating time of the system. Such a fuel cell system is ideally suited for submersible and aerospace applications where anaerobic conditions prevail.

  1. The Removal of Cu (II) from Aqueous Solution using Sodium Borohydride as a Reducing Agent

    Science.gov (United States)

    Sithole, N. T.; Ntuli, F.; Mashifana, T.

    2018-03-01

    The removal and recovery of metals from wastewater has been a subject of significant importance due the negative impact these toxic metals have on human health and the environment as a result of water and soil pollution. Increased use of the metals and chemicals in the process industries has resulted in generation of large quantity of effluents that contains high level of toxic metals and other pollutants. The objective of this work was to recover of Cu in its elemental form as metallic powder from aqueous solution using NaBH4 as a reducing agent. Reductive precipitation was achieved in a batch reactor at 65°C using Cu powder as a seeding material. This study also investigated the effect of concentration of sodium borohydride (NaBH4) as a reducing agent. The amount of NaBH4 was varied based on mole ratios which are 1:1, 1:0.25 and 1:0.1 to recover Cu from synthetic wastewater. The results obtained showed that sodium borohydride is an effective reducing agent to recover Cu from wastewater. The optimum concentration of NaBH4 that gives the best results the 1:1 molar ratio with over 99% Cu removal.

  2. Synthesis and characterization of Pa(IV), Np(IV), and Pu(IV) borohydrides

    Energy Technology Data Exchange (ETDEWEB)

    Banks, R.H.; Edelstein, N.M.

    1979-12-01

    The actinide borohydrides of Pa, Np, and Pu have been prepared and some of their physical and optical properties measured. X-ray powder diffraction photographs of Pa(BH/sub 4/)/sub 4/ have shown that it is isostructural to Th(BH/sub 4/)/sub 4/ and U(BH/sub 4/)/sub 4/. Np(BH/sub 4/)/sub 4/ and Pu(BH/sub 4/)/sub 4/ are much more volatile than the borohydrides of Th, Pa, and U and are liquids at room temperature. Results from low-temperature single-crystal x-ray diffraction investigation of Np(BH/sub 4/)/sub 4/ show that its structure is very similar to Zr(BH/sub 4/)/sub 4/. With the data from low-temperature infrared and Raman spectra, a normal coordinate analysis on Np(BH/sub 4/)/sub 4/ and Np(BD/sub 4/)/sub 4/ has been completed. EPR experiments on Np(BH/sub 4/)/sub 4//Zr(BH/sub 4/)/sub 4/ and Np(BD/sub 4/)/sub 4//Zr(BD/sub 4/)/sub 4/ have characterized the ground electronic state. 5 figures.

  3. 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...

  4. A direct borohydride fuel cell with a polymer fiber membrane and non-noble metal catalysts.

    Science.gov (United States)

    Yang, Xiaodong; Liu, Yongning; Li, Sai; Wei, Xiaozhu; Wang, Li; Chen, Yuanzhen

    2012-01-01

    Polymer electrolyte membranes (PEM) and Pt-based catalysts are two crucial components which determine the properties and price of fuel cells. Even though, PEM faces problem of fuel crossover in liquid fuel cells such as direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC), which lowers power output greatly. Here, we report a DBFC in which a polymer fiber membrane (PFM) was used, and metal oxides, such as LaNiO₃ and MnO₂, were used as cathode catalysts, meanwhile CoO was used as anode catalyst. Peak power density of 663 mW·cm⁻² has been achieved at 65°C, which increases by a factor of 1.7-3.7 compared with classic DBFCs. This fuel cell structure can also be extended to other liquid fuel cells, such as DMFC.

  5. A direct borohydride fuel cell with a polymer fiber membrane and non-noble metal catalysts

    Science.gov (United States)

    Yang, Xiaodong; Liu, Yongning; Li, Sai; Wei, Xiaozhu; Wang, Li; Chen, Yuanzhen

    2012-08-01

    Polymer electrolyte membranes (PEM) and Pt-based catalysts are two crucial components which determine the properties and price of fuel cells. Even though, PEM faces problem of fuel crossover in liquid fuel cells such as direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC), which lowers power output greatly. Here, we report a DBFC in which a polymer fiber membrane (PFM) was used, and metal oxides, such as LaNiO3 and MnO2, were used as cathode catalysts, meanwhile CoO was used as anode catalyst. Peak power density of 663 mW.cm-2 has been achieved at 65°C, which increases by a factor of 1.7-3.7 compared with classic DBFCs. This fuel cell structure can also be extended to other liquid fuel cells, such as DMFC.

  6. Acetic acid, a relatively green single-use catalyst for hydrogen generation from sodium borohydride

    Energy Technology Data Exchange (ETDEWEB)

    Akdim, O.; Demirci, U.B.; Miele, P. [Universite Lyon 1, CNRS, UMR 5615, Laboratoire des Multimateriaux et Interfaces, 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France)

    2009-09-15

    Acid-catalyzed hydrolysis of sodium borohydride (NaBH{sub 4}) has been studied (reactivity and kinetics) at high acid concentration (0.32 M). A mineral (hydrochloric acid, HCl) and an organic benign (acetic acid, CH{sub 3}COOH) acid have been chosen. Our study has three distinct objectives, namely: (i) combining the simplicity of the storage of solid NaBH{sub 4} with the simplicity of the aqueous solution of acid; (ii) showing CH{sub 3}COOH can be as reactive as HCl in specific well-chosen operating conditions; and (iii) emphasizing the relative greenness of the CH{sub 3}COOH-based process. All of these objectives have been fulfilled and show that CH{sub 3}COOH is a benign relatively green acid catalyst of choice for catalyzing hydrogen generation from NaBH{sub 4}, the acid-water-NaBH{sub 4} system being quite simple. (author)

  7. A direct borohydride fuel cell with a polymer fiber membrane and non-noble metal catalysts

    Science.gov (United States)

    Yang, Xiaodong; Liu, Yongning; Li, Sai; Wei, Xiaozhu; Wang, Li; Chen, Yuanzhen

    2012-01-01

    Polymer electrolyte membranes (PEM) and Pt-based catalysts are two crucial components which determine the properties and price of fuel cells. Even though, PEM faces problem of fuel crossover in liquid fuel cells such as direct methanol fuel cell (DMFC) and direct borohydride fuel cell (DBFC), which lowers power output greatly. Here, we report a DBFC in which a polymer fiber membrane (PFM) was used, and metal oxides, such as LaNiO3 and MnO2, were used as cathode catalysts, meanwhile CoO was used as anode catalyst. Peak power density of 663 mW·cm−2 has been achieved at 65°C, which increases by a factor of 1.7–3.7 compared with classic DBFCs. This fuel cell structure can also be extended to other liquid fuel cells, such as DMFC. PMID:22880160

  8. Magnesium Ethylenediamine Borohydride as Solid-State Electrolyte for Magnesium Batteries

    Science.gov (United States)

    Roedern, Elsa; Kühnel, Ruben-Simon; Remhof, Arndt; Battaglia, Corsin

    2017-04-01

    Solid-state magnesium ion conductors with exceptionally high ionic conductivity at low temperatures, 5 × 10-8 Scm-1 at 30 °C and 6 × 10-5 Scm-1 at 70 °C, are prepared by mechanochemical reaction of magnesium borohydride and ethylenediamine. The coordination complexes are crystalline, support cycling in a potential window of 1.2 V, and allow magnesium plating/stripping. While the electrochemical stability, limited by the ethylenediamine ligand, must be improved to reach competitive energy densities, our results demonstrate that partially chelated Mg2+ complexes represent a promising platform for the development of an all-solid-state magnesium battery.

  9. Synthesis, structure and properties of bimetallic sodium rare-earth (RE) borohydrides, NaRE(BH4)4, RE = Ce, Pr, Er or Gd

    DEFF Research Database (Denmark)

    Payandeh Gharibdoust, Seyedhosein; Ravnsbæk, Dorthe B.; Černý, Radovan

    2017-01-01

    Formation, stability and properties of new metal borohydrides within RE(BH4)3-NaBH4, RE = Ce, Pr, Er or Gd is investigated. Three new bimetallic sodium rare-earth borohydrides, NaCe(BH4)4, NaPr(BH4)4 and NaEr(BH4)4 are formed based on an addition reaction between NaBH4 and halide free rare-earth...... to formation of metal hydrides and possibly slower formation of sodium borohydride. The dehydrogenated state clearly contains rare-earth metal borides, which stabilize boron in the dehydrogenated state....

  10. Scandium and yttrium metallocene borohydride complexes: comparisons of (BH4)1- vs. (BPh4)1- coordination and reactivity.

    Science.gov (United States)

    Demir, Selvan; Siladke, Nathan A; Ziller, Joseph W; Evans, William J

    2012-08-28

    The synthetically accessible borohydride complexes (C(5)Me(4)H)(2)Ln(THF)(BH(4)) and (C(5)Me(5))(2)Ln(THF)(BH(4)) (Ln = Sc, Y) were examined as precursors alternative to the heavily-used tetraphenylborate analogs, [(C(5)Me(4)H)(2)Ln][BPh(4)] and [(C(5)Me(5))(2)Ln][BPh(4)], employed in LnA(2)A'/M reduction reactions (A = anion; M = alkali metal) that generate "LnA(2)" reactivity and form reduced dinitrogen complexes [(C(5)R(5))(2)(THF)(x)Ln](2)(μ-η(2):η(2)-N(2)) (x = 0, 1). The crystal structures of the yttrium borohydrides, (C(5)Me(4)H)(2)Y(THF)(μ-H)(3)BH, 1, and (C(5)Me(5))(2)Y(THF)(μ-H)(2)BH(2), 2, were determined for comparison with those of the yttrium tetraphenylborates, [(C(5)Me(4)H)(2)Y][(μ-Ph)(2)BPh(2)], 3, and [(C(5)Me(5))(2)Y][(μ-Ph)(2)BPh(2)], 4. The complex (C(5)Me(4)H)(2)Sc(μ-H)(2)BH(2), 5, was synthesized and structurally characterized for comparison with (C(5)Me(5))(2)Sc(μ-H)(2)BH(2), 6, [(C(5)Me(4)H)(2)Sc][(μ-Ph)BPh(3)], 7, and [(C(5)Me(5))(2)Sc][(μ-Ph)BPh(3)], 8. Structural information was also obtained on the borohydride derivatives, (C(5)Me(4)H)(2)Sc(μ-H)(2)BC(8)H(14), 9, and (C(5)Me(5))(2)Sc(μ-H)(2)BC(8)H(14), 10, obtained from 9-borabicyclo(3.3.1)nonane (9-BBN) and (C(5)Me(4)R)(2)Sc(η(3)-C(3)H(5)), where R = H, 11; Me, 12. The preference of the metals for borohydride over tetraphenylborate binding was shown by the facile displacement of (BPh(4))(1-) in 3, 4, 7, and 8 by (BH(4))(1-) to make the respective borohydride complexes 1, 2, 5, and 6. These results are consistent with the fact that the borohydrides are not as useful as precursors in A(2)LnA'/M reductions of N(2). An unusual structural isomer of [(C(5)Me(4)H)(2)Sc](2)(μ-η(2):η(2)-N(2)), 13', was isolated from this study that shows the variations in ligand orientation that can occur in the solid state.

  11. First-principles studies of phase stability and crystal structures in Li-Zn mixed-metal borohydrides

    Science.gov (United States)

    Wang, Yongli; Zhang, Yongsheng; Wolverton, C.

    2013-07-01

    We address the problem of finding mixed-metal borohydrides with favorable thermodynamics and illustrate the approach using the example of LiZn2(BH4)5. Using density functional theory (DFT), along with the grand-canonical linear programming method (GCLP), we examine the experimentally and computationally proposed crystal structures and the finite-temperature thermodynamics of dehydrogenation for the quaternary hydride LiZn2(BH4)5. We find the following: (i) For LiZn2(BH4)5, DFT calculations of the experimental crystal structures reveal that the structure from the neutron diffraction experiments of Ravnsbæk is more stable [by 24 kJ/(mol f.u.)] than that based on a previous x-ray study. (ii) Our DFT calculations show that when using the neutron-diffraction structure of LiZn2(BH4)5, the recently theoretically predicted LiZn(BH4)3 compound is unstable with respect to the decomposition into LiZn2(BH4)5+LiBH4. (iii) GCLP calculations show that even though LiZn2(BH4)5 is a combination of weakly [Zn(BH4)2] and strongly (LiBH4) bound borohydrides, its decomposition is not intermediate between the two individual borohydrides. Rather, we find that the decomposition of LiZn2(BH4)5 is divided into a weakly exothermic step [LiZn2(BH4)5→2Zn+(1)/(5)LiBH4+(2)/(5)Li2B12H12+(36)/(5)H2] and three strong endothermic steps (12LiBH4→10LiH+Li2B12H12+13H2; Zn+LiH→LiZn+(1)/(2)H2; 2Zn+Li2B12H12→2LiZn+12B+6H2). DFT-calculated ΔHZPET=0K values for the first three LiZn2(BH4)5 decomposition steps are -19, +37, +74 kJ/(mol H2), respectively. The behavior of LiZn2(BH4)5 shows that mixed-metal borohydrides formed by mixing borohydrides of high and low thermodynamics stabilities do not necessarily have an intermediate decomposition tendency. Our results suggest the correct strategy to find intermediate decomposition in mixed-metal borohydrides is to search for stable mixed-metal products such as ternary metal borides.

  12. Introducing catalyst in alkaline membrane for improved performance direct borohydride fuel cells

    Science.gov (United States)

    Qin, Haiying; Lin, Longxia; Chu, Wen; Jiang, Wei; He, Yan; Shi, Qiao; Deng, Yonghong; Ji, Zhenguo; Liu, Jiabin; Tao, Shanwen

    2018-01-01

    A catalytic material is introduced into the polymer matrix to prepare a novel polymeric alkaline electrolyte membrane (AEM) which simultaneously increases ionic conductivity, reduces the fuel cross-over. In this work, the hydroxide anion exchange membrane is mainly composed of poly(vinylalcohol) and alkaline exchange resin. CoCl2 is added into the poly(vinylalcohol) and alkaline exchange resin gel before casting the membrane to introduce catalytic materials. CoCl2 is converted into CoOOH after the reaction with KOH solution. The crystallinity of the polymer matrix decreases and the ionic conductivity of the composite membrane is notably improved by the introduction of Co-species. A direct borohydride fuel cell using the composite membrane exhibits an open circuit voltage of 1.11 V at 30 °C, which is notably higher than that of cells using other AEMs. The cell using the composite membrane achieves a maximum power density of 283 mW cm-2 at 60 °C while the cell using the membrane without Co-species only reaches 117 mW cm-2 at the same conditions. The outstanding performance of the cell using the composite membrane benefits from impregnation of the catalytic Co-species in the membrane, which not only increases the ionic conductivity but also reduces electrode polarization thus improves the fuel cell performance. This work provides a new approach to develop high-performance fuel cells through adding catalysts in the electrolyte membrane.

  13. Ultrahigh figure-of-merit for hydrogen generation from sodium borohydride using ternary metal catalysts

    Science.gov (United States)

    Hu, Lunghao; Ceccato, R.; Raj, R.

    We report further increase in the figure-of-merit (FOM) for hydrogen generation from NaBH 4 than reported in an earlier paper [1], where a sub-nanometer layer of metal catalysts are deposited on carbon nanotube paper (CNT paper) that has been functionalized with polymer-derived silicon carbonitride (SiCN) ceramic film. Ternary, Ru-Pd-Pt, instead of the binary Pd-Pt catalyst used earlier, together with a thinner CNT paper is shown to increase the figure-of-merit by up to a factor of six, putting is above any other known catalyst for hydrogen generation from NaBH 4. The catalysts are prepared by first impregnating the functionalized CNT-paper with solutions of the metal salts, followed by reduction in a sodium borohydride solution. The reaction mechanism and the catalyst efficiency are described in terms of an electric charge transfer, whereby the negative charge on the BH 4 - ion is exchanged with hydrogen via the electronically conducting SiCN/CNT substrate [1].

  14. Prediction of high-Tc conventional superconductivity in the ternary lithium borohydride system

    Science.gov (United States)

    Kokail, Christian; von der Linden, Wolfgang; Boeri, Lilia

    2017-12-01

    We investigate the superconducting ternary lithium borohydride phase diagram at pressures of 0 and 200 GPa using methods for evolutionary crystal structure prediction and linear-response calculations for the electron-phonon coupling. Our calculations show that the ground state phase at ambient pressure, LiBH4, stays in the P n m a space group and remains a wide band-gap insulator at all pressures investigated. Other phases along the 1 :1 :x Li:B:H line are also insulating. However, a full search of the ternary phase diagram at 200 GPa revealed a metallic Li2BH6 phase, which is thermodynamically stable down to 100 GPa. This superhydride phase, crystallizing in a F m 3 ¯m space group, is characterized by sixfold hydrogen-coordinated boron atoms occupying the fcc sites of the unit cell. Due to strong hydrogen-boron bonding this phase displays a critical temperature of ˜100 K between 100 and 200 GPa. Our investigations confirm that ternary compounds used in hydrogen-storage applications should exhibit high-Tc conventional superconductivity in diamond anvil cell experiments, and suggest a viable route to optimize the superconducting behavior of high-pressure hydrides, exploiting metallic covalent bonds.

  15. Electroless Nickel-Based Catalyst for Diffusion Limited Hydrogen Generation through Hydrolysis of Borohydride

    Directory of Open Access Journals (Sweden)

    Shannon P. Anderson

    2013-07-01

    Full Text Available Catalysts based on electroless nickel and bi-metallic nickel-molybdenum nanoparticles were synthesized for the hydrolysis of sodium borohydride for hydrogen generation. The catalysts were synthesized by polymer-stabilized Pd nanoparticle-catalyzation and activation of Al2O3 substrate and electroless Ni or Ni-Mo plating of the substrate for selected time lengths. Catalytic activity of the synthesized catalysts was tested for the hydrolyzation of alkaline-stabilized NaBH4 solution for hydrogen generation. The effects of electroless plating time lengths, temperature and NaBH4 concentration on hydrogen generation rates were analyzed and discussed. Compositional analysis and surface morphology were carried out for nano-metallized Al2O3 using Scanning Electron Micrographs (SEM and Energy Dispersive X-Ray Microanalysis (EDAX. The as-plated polymer-stabilized electroless nickel catalyst plated for 10 min and unstirred in the hydrolysis reaction exhibited appreciable catalytic activity for hydrolysis of NaBH4. For a zero-order reaction assumption, activation energy of hydrogen generation using the catalyst was estimated at 104.6 kJ/mol. Suggestions are provided for further work needed prior to using the catalyst for portable hydrogen generation from aqueous alkaline-stabilized NaBH4 solution for fuel cells.

  16. 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)

  17. Combined X-ray and Raman Studies on the Effect of Cobalt Additives on the Decomposition of Magnesium Borohydride

    OpenAIRE

    Zavorotynska, Olena; Deledda, Stefano; Vitillo, Jenny; Saldan, Ivan; Guzik, Matylda; Baricco, Marcello; Walmsley, John; Muller, Jiri; Hauback, Bjørn

    2015-01-01

    Magnesium borohydride (Mg(BH4)2) is one of the most promising hydrogen storage materials. Its kinetics of hydrogen desorption, reversibility, and complex reaction pathways during decomposition and rehydrogenation, however, present a challenge, which has been often addressed by using transition metal compounds as additives. In this work the decomposition of Mg(BH4)2 ball-milled with CoCl2 and CoF2 additives, was studied by means of a combination of several in-situ techniques. Synchrotron X-ray...

  18. Chiral Compounds and Green Chemistry in Undergraduate Organic Laboratories: Reduction of a Ketone by Sodium Borohydride and Baker's Yeast

    Science.gov (United States)

    Pohl, Nicola; Clague, Allen; Schwarz, Kimberly

    2002-06-01

    We describe an integrated set of experiments for the undergraduate organic laboratory that allows students to compare and contrast biological and chemical means of introducing chirality into a molecule. The racemic reduction of ethyl acetoacetate with sodium borohydride and the same reduction in the presence of a tartaric acid ligand are described, and a capillary gas chromatography column packed with a chiral material for product analysis is introduced. The results of these two hydride reactions are compared with the results of a common undergraduate experiment, the baker's yeast reduction of ethyl acetoacetate.

  19. 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

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

    Directory of Open Access Journals (Sweden)

    Hilsamar Félix-Rivera

    2011-01-01

    Full Text Available 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.

  1. Optimized hydrogen generation in a semicontinuous sodium borohydride hydrolysis reactor for a 60 W-scale fuel cell stack

    Science.gov (United States)

    Arzac, G. M.; Fernández, A.; Justo, A.; Sarmiento, B.; Jiménez, M. A.; Jiménez, M. M.

    Catalyzed hydrolysis of sodium borohydride (SBH) is a promising method for the hydrogen supply of fuel cells. In this study a system for controlled production of hydrogen from aqueous sodium borohydride (SBH) solutions has been designed and built. This simple and low cost system operates under controlled addition of stabilized SBH solutions (fuel solutions) to a supported CoB catalyst. The system works at constant temperature delivering hydrogen at 1 L min -1 constant rate to match a 60-W polymer electrolyte membrane fuel cell (PEMFC). For optimization of the system, several experimental conditions were changed and their effect was investigated. A simple model based only on thermodynamic considerations was proposed to optimize system parameters at constant temperature and hydrogen evolution rate. It was found that, for a given SBH concentration, the use of the adequate fuel addition rate can maximize the total conversion and therefore the gravimetric storage capacity. The hydrogen storage capacity was as high as 3.5 wt% for 19 wt% SBH solution at 90% fuel conversion and an operation temperature of 60 °C. It has been demonstrated that these optimized values can also be achieved for a wide range of hydrogen generation rates. Studies on the durability of the catalyst showed that a regeneration step is needed to restore the catalytic activity before reusing.

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

    International Nuclear Information System (INIS)

    Felix-Rivera, H.; Gonzalez, R.; Rodriguez, G.D.M.; Oliva, M. P.; Hernandez-Rivera, S.P.; Rios-Velazquez, C.

    2011-01-01

    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.

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

    International Nuclear Information System (INIS)

    Stingl, Johannes

    2013-01-01

    In this thesis the ultrafast electronic polarisation in the crystalline material lithium borohydride (LiBH 4 ) 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 (LiBH 4 ) to strong electronic fields with optical frequencies, which leads to charge relocation accompanied by electronic polarisation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, David [U.S. Borax Inc., Rio Tinto, CO (United States); Neiner, Doinita [U.S. Borax Inc., Rio Tinto, CO (United States); Bowden, Mark [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Whittemore, Sean [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Holladay, Jamie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Huang, Zhenguo [Univ. of Wollongong, NSW (Australia); Autrey, Tom [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-10-01

    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)3) ratio, i.e., M/B, to obtain a distribution of polyborate anions. For a 1:1 mole ratio of NaOH to B(OH)3, M/B = 1, the ratio of the hydrolysis product formed from NaBH4 hydrolysis, the sole borate species formed and observed by 11B NMR is sodium metaborate, NaB(OH)4. When the ratio is 1:3 NaOH to B(OH)3, M/B = 0.33, a mixture of borate anions is formed and observed as a broad peak in the 11B 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, NaB3H8, 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% NaB3H8 solution in water yields a solution having the same complex polyborate mixture as formed by mixing a 1:3 molar ratio of NaOH and B(OH)3 and releases >8 eq of H2. By optimizing the M/B ratio a complex mixture of soluble products, including B3O3(OH)52-, B4O5(OH)42-, B3O3(OH)4-, B5O6(OH)4- and B(OH)3, can be maintained as a single liquid phase throughout the hydrogen release process. Consequently, hydrolysis of NaB3H8 can provide a 40% increase in H2 storage density compared to the hydrolysis of NaBH4 given the decreased solubility of sodium metaborate. The authors would like to thank Jim Sisco and Paul Osenar of

  5. 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.

  6. Combined X-ray and Raman Studies on the Effect of Cobalt Additives on the Decomposition of Magnesium Borohydride

    Directory of Open Access Journals (Sweden)

    Olena Zavorotynska

    2015-08-01

    Full Text Available Magnesium borohydride (Mg(BH42 is one of the most promising hydrogen storage materials. Its kinetics of hydrogen desorption, reversibility, and complex reaction pathways during decomposition and rehydrogenation, however, present a challenge, which has been often addressed by using transition metal compounds as additives. In this work the decomposition of Mg(BH42 ball-milled with CoCl2 and CoF2 additives, was studied by means of a combination of several in-situ techniques. Synchrotron X-ray diffraction and Raman spectroscopy were used to follow the phase transitions and decomposition of Mg(BH42. By comparison with pure milled Mg(BH42, the temperature for the γ → ε phase transition in the samples with CoF2 or CoCl2 additives was reduced by 10–45 °C. In-situ Raman measurements showed the formation of a decomposition phase with vibrations at 2513, 2411 and 766 cm−1 in the sample with CoF2. Simultaneous X-ray absorption measurements at the Co K-edge revealed that the additives chemically transformed to other species. CoF2 slowly reacted upon heating till ~290 °C, whereas CoCl2 transformed drastically at ~180 °C.

  7. Hydrolysis and regeneration of sodium borohydride (NaBH4) - A combination of hydrogen production and storage

    Science.gov (United States)

    Chen, W.; Ouyang, L. Z.; Liu, J. W.; Yao, X. D.; Wang, H.; Liu, Z. W.; Zhu, M.

    2017-08-01

    Sodium borohydride (NaBH4) hydrolysis is a promising approach for hydrogen generation, but it is limited by high costs, low efficiency of recycling the by-product, and a lack of effective gravimetric storage methods. Here we demonstrate the regeneration of NaBH4 by ball milling the by-product, NaBO2·2H2O or NaBO2·4H2O, with MgH2 at room temperature and atmospheric pressure without any further post-treatment. Record yields of NaBH4 at 90.0% for NaBO2·2H2O and 88.3% for NaBO2·4H2O are achieved. This process also produces hydrogen from the splitting of coordinate water in hydrated sodium metaborate. This compensates the need for extra hydrogen for generating MgH2. Accordingly, we conclude that our unique approach realizes an efficient and cost-effective closed loop system for hydrogen production and storage.

  8. The influence of LiH on the rehydrogenation behavior of halide free rare earth (RE) borohydrides (RE = Pr, Er).

    Science.gov (United States)

    Heere, Michael; Payandeh GharibDoust, Seyed Hosein; Frommen, Christoph; Humphries, Terry D; Ley, Morten B; Sørby, Magnus H; Jensen, Torben R; Hauback, Bjørn C

    2016-09-21

    Rare earth (RE) metal borohydrides are receiving immense consideration as possible hydrogen storage materials and solid-state Li-ion conductors. In this study, halide free Er(BH4)3 and Pr(BH4)3 have been successfully synthesized for the first time by the combination of mechanochemical milling and/or wet chemistry. Rietveld refinement of Er(BH4)3 confirmed the formation of two different Er(BH4)3 polymorphs: α-Er(BH4)3 with space group Pa3[combining macron], a = 10.76796(5) Å, and β-Er(BH4)3 in Pm3[combining macron]m with a = 5.4664(1) Å. A variety of Pr(BH4)3 phases were found after extraction with diethyl ether: α-Pr(BH4)3 in Pa3[combining macron] with a = 11.2465(1) Å, β-Pr(BH4)3 in Pm3[combining macron]m with a = 5.716(2) Å and LiPr(BH4)3Cl in I4[combining macron]3m, a = 11.5468(3) Å. Almost phase pure α-Pr(BH4)3 in Pa3[combining macron] with a = 11.2473(2) Å was also synthesized. The thermal decomposition of Er(BH4)3 and Pr(BH4)3 proceeded without the formation of crystalline products. Rehydrogenation, as such, was not successful. However, addition of LiH promoted the rehydrogenation of RE hydride phases and LiBH4 from the decomposed RE(BH4)3 samples.

  9. Sodium borohydride hydrogen generator using Co–P/Ni foam catalysts for 200 W proton exchange membrane fuel cell system

    International Nuclear Information System (INIS)

    Oh, Taek Hyun; Gang, Byeong Gyu; Kim, Hyuntak; Kwon, Sejin

    2015-01-01

    The response characteristics of electroless-deposited Co–P/Ni foam catalysts for sodium borohydride hydrolysis were investigated. The effect of nickel foam geometry on the properties of the catalysts was evaluated. As the PPI (pores per inch) of the nickel foam increased, the hydrogen generation rate per gram of the deposited catalyst increased due to an increase in surface area. The response characteristics of various catalysts were compared under real operating conditions. When a thin nickel foam with high PPI was used, the response characteristics of the catalyst improved due to an increase in the amount of the deposited catalyst and surface area. Finally, a 200 W PEMFC (proton exchange membrane fuel cell) system using electroless-deposited Co–P/Ni foam (110 PPI) catalyst was investigated. The response time to reach a hydrogen generation rate sufficient for a 200 W PEMFC was 71 s, and the energy density of a 200 W fuel cell system for producing 600 Wh was 252.1 Wh/kg. A fuel cell system using Co–P/Ni foam catalysts can be widely used as a power source for mobile applications due to fast response characteristics and high energy density. - Highlights: • Response characteristics of Co–P/Ni foam catalysts are investigated. • Catalytic activity is improved with increase in PPI (pores per inch) of Ni foam. • Co–P/Ni foam (110 PPI) catalyst has improved response characteristics. • The energy density of a 200 W PEMFC system for producing 600 Wh is 252.1 Wh/kg. • Co–P/Ni foam (110 PPI) catalyst is suitable for fuel cell system.

  10. Fully automated synthesis of 4-[18F]fluorobenzylamine based on borohydride/NiCl2 reduction.

    Science.gov (United States)

    Way, Jenilee; Wuest, Frank

    2013-04-01

    4-[(18)F]Fluorobenzylamine ([(18)F]FBA) is an important building block for the synthesis of (18)F-labeled compounds. Synthesis of [(18)F]FBA usually involves application of strong reducing agents like LiAlH4 which is challenging to handle in automated synthesis units (ASUs). Therefore, alternative methods for the preparation of [(18)F]FBA compatible with remotely-controlled syntheses in ASUs are needed. (18)F]FBA was prepared in a remotely-controlled synthesis unit (GE TRACERlab™ FX) based on Ni(II)-mediated borohydride exchange resin (BER) reduction of 4-[(18)F]fluorobenzonitrile ([(18)F]FBN). [(18)F]FBA was used for the synthesis of novel thiol-reactive prosthetic group 4-[(18)F]fluorobenzyl)maleimide [(18)F]FBM and Hsp90 inhibitor 17-(4-[(18)F]fluorobenzylamino)-17-demethoxy-geldanamycin [(18)F] GA. [(18)F]FBA could be prepared in high radiochemical yield greater than 80% (decay-corrected) within 60min. In a typical experiment, 7.4GBq of [(18)F]FBA could be obtained in high radiochemical purity of greater than 95% starting from 10GBq of cyclotron-produced n.c.a. [(18)F]fluoride. [(18)F]FBA was used for the preparation of 4-[(18)F]fluorobenzyl)maleimide as a novel prosthetic group for labeling of thiol groups as demonstrated with tripeptide glutathione. [(18)F]FBA was also used as building block for the syntheses of small molecules as exemplified by the preparation of Hsp90 inhibitor 17-(4-[(18)F]fluorobenzylamino)-17-demethoxy-geldanamycin. The described remotely-controlled synthesis of [(18)F]FBA will significantly improve the availability of [(18)F]FBA as an important and versatile building block for the development of novel (18)F-labeled compounds containing a fluorobenzylamine moiety. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Electrochemical oxidation of ethanol using PtRh/C electrocatalysts in alkaline medium and synthesized by sodium borohydride and alcohol reduction

    International Nuclear Information System (INIS)

    Fontes, Eric Hossein

    2017-01-01

    PtRh/C were prepared by the following atomic proportions: (100,0), (0,100), (90,10), (70,30) and (50,50). The methods employed in the synthesis of these materials were reduction by sodium borohydride and reduction by alcohol. The metal salts used were H 2 PtCl 6 3•6H 2 0 and (RhNO 3 ) 3 , the support used was Carbon black XC72 and the bulk metal composition was 20% and 80% of support. The electrocatalysts were characterized by Energy Dispersive X-ray spectroscopy, X-ray diffraction and Transmission electron microscopy. The ethanol electrochemical oxidation mechanism was investigated by in situ Fourier Transform Infrared Spectroscopy couple to an Attenuated Total Reflection technique. The electrocatalytic activity were evaluated by Cyclic Voltammetry, Linear Sweep Voltammetry and Chronoamperometry techniques. The Fuel Cells tests were made in a single direct alcohol fuel cell with alkaline membrane. The working electrodes were prepared by a thin porous coating technique. X-ray diffraction allowed to verify metallic alloys, segregate phases and to calculate the percentage of metallic alloys. It was else possible to identify crystallographic phases. Infrared Spectroscopy allowed to verify that the electrochemical oxidation of ethanol was carried out by an incomplete mechanism. PtRh(70:30)/C prepared by sodium borohydride produced large amounts of carbon dioxide and acetaldehyde. Rh/C showed electrocatalytic activity when compared with other materials studied.

  12. Improvement of energy conversion efficiency and power generation in direct borohydride-hydrogen peroxide fuel cell: The effect of Ni-M core-shell nanoparticles (M = Pt, Pd, Ru)/Multiwalled Carbon Nanotubes on the cell performance

    Science.gov (United States)

    Hosseini, M. G.; Mahmoodi, R.

    2017-12-01

    In this study, core@shell nanoparticles with Ni as a core material and Pt, Pd and Ru as shell materials are synthesized on multiwalled carbon nanotube (MWCNT) as catalyst support using the sequence reduction method. The influence of Ni@Pt, Ni@Pd and Ni@Ru core@shell nanoparticles on MWCNT toward borohydride oxidation in alkaline solution is investigated by various three-electrode electrochemical techniques. Also, the impact of these anodic electrocatalysts on the performance of direct borohydride-hydrogen peroxide fuel cell (DBHPFC) is evaluated. The structural and morphological properties of electrocatalysts are studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). The results of three electrode investigations show that Ni@Pd/MWCNT has excellent catalytic activity since borohydride oxidation current density on Ni@Pd/MWCNT (34773.27 A g-1) is 1.37 and 9.19 times higher than those of Ni@Pt/MWCNT (25347.27 A g-1) and Ni@Ru/MWCNT (3782.83 A g-1), respectively. Also, the energy conversion efficiency and power density of DBHPFC with Ni@Pd/MWCNT (246.82 mW cm-2) increase to 34.27% and 51.53% respect to Ni@Pt/MWCNT (162.24 mW cm-2) and Ni@Ru/MWCNT (119.62 mW cm-2), respectively. This study reveals that Ni@Pd/MWCNT has highest activity toward borohydride oxidation and stability in fuel cell.

  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)

    Brandalise, Michele

    2010-01-01

    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)

  14. Hydrogen generation from the hydrolysis of sodium borohydride using chemically modified multiwalled carbon nanotubes with pyridinium based ionic liquid and decorated with highly dispersed Mn nanoparticles

    Science.gov (United States)

    Chinnappan, Amutha; Puguan, John Marc C.; Chung, Wook-Jin; Kim, Hern

    2015-10-01

    Multiwalled carbon nanotubes (MWCNTs)/Ionic liquid (IL)/Mn nanohybrids are synthesized and their catalytic activity is examined for hydrogen generation from the hydrolysis of sodium borohydride (NaBH4). Transmission electron microscopy reveals that Mn nanoparticles well-distributed on the MWCNTs surface. Energy dispersive x-ray spectrometer and x-ray photoelectron spectroscopy confirms the presence of Mn and Ni atom in the nanohybrids. The nanohybrids exhibit excellent catalytic lifetime and gives the total turnover number of 18496 mol H2/mol catalyst in the hydrolysis of NaBH4, which can be attributed to the presence of Mn atom and IL containing nickel halide anion. It is worthy of note that a very small amount of catalyst is used for this hydrolysis reaction. The activation energy is found to be 40.8 kJ/mol by MWCNTs/IL/Mn nanohybrids from the kinetic study of the hydrogen generation from the hydrolysis of NaBH4. The improved hydrogen generation rate, lower activation energy, and less expensive make the nanohybrids promising candidate as catalyst for the hydrogen generation from NaBH4 solution. The nanohybrids are easy to prepare, store and yet catalytically active. The recycling process is very simple and further purification is not tedious.

  15. Membraneless, room-temperature, direct borohydride/cerium fuel cell with power density of over 0.25 W/cm2.

    Science.gov (United States)

    Da Mota, Nicolas; Finkelstein, David A; Kirtland, Joseph D; Rodriguez, Claudia A; Stroock, Abraham D; Abruña, Héctor D

    2012-04-11

    The widespread adoption and deployment of fuel cells as an alternative energy technology have been hampered by a number of formidable technical challenges, including the cost and long-term stability of electrocatalyst and membrane materials. We present a microfluidic fuel cell that overcomes many of these obstacles while achieving power densities in excess of 250 mW/cm(2). The poisoning and sluggish reaction rate associated with CO-contaminated H(2) and methanol, respectively, are averted by employing the promising, high-energy density fuel borohydride. The high-overpotential reaction of oxygen gas at the cathode is supplanted by the high-voltage reduction of cerium ammonium nitrate. Expensive, ineffective membrane materials are replaced with laminar flow and a nonselective, porous convection barrier to separate the fuel and oxidant streams. The result is a Nafion-free, room-temperature fuel cell that has the highest power density per unit mass of Pt catalyst employed for a non-H(2) fuel cell, and exceeds the power density of a typical H(2) fuel cell by 50%. © 2012 American Chemical Society

  16. 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.

  17. Sodium Borohydride Reduction of Aqueous Silver-Iron-Nickel Solutions: a Chemical Route to Synthesis of Low Thermal Expansion-High Conductivity Ag-Invar Alloys

    Science.gov (United States)

    Sterling, E. A.; Stolk, J.; Hafford, L.; Gross, M.

    2009-07-01

    Thermal management is a critical concern in the design and performance of electronics systems. If heat extraction and thermal expansion are not properly addressed, the thermal mismatch among dissimilar materials may give rise to high thermal stresses or interfacial shear strains, and ultimately to premature system failure. In this article, we present a chemical synthesis process that yields Ag-Invar (64Fe-36Ni) alloys with a range of attractive properties for thermal management applications. Sodium borohydride reduction of an aqueous Ag-Fe-Ni metal salt solution produces nanocrystalline powders, and conventional powder processing converts this powder to fine-grained alloys. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy, thermomechanical analysis, and electrical conductivity measurements; thermal conductivity is estimated using the Wiedemann-Franz law. Sintering of Ag-Fe-Ni powders leads to the formation of two-phase silver-Invar alloys with low coefficients of thermal expansion (CTEs) and relatively high electrical conductivities. A sample of 50Ag-50Invar exhibits a CTE of 8.76 μm/(m· °C) and an estimated thermal conductivity of 236 W/(m·K). The Ag-Invar alloys offer thermodynamic stability and tailorable properties, and they may help address the need for improved packaging materials.

  18. Determination of inorganic mercury and total mercury in biological and environmental samples by flow injection-cold vapor-atomic absorption spectrometry using sodium borohydride as the sole reducing agent

    International Nuclear Information System (INIS)

    Rio Segade, Susana; Tyson, Julian F.

    2003-01-01

    A simple, fast, precise and accurate method to determine inorganic mercury and total mercury in biological and environmental samples was developed. The optimized flow-injection mercury system permitted the separate determination of inorganic mercury and total mercury using sodium borohydride as reducing agent. Inorganic mercury was selectively determined after reduction with 10 -4 % w/v sodium borohydride, while total mercury was determined after reduction with 0.75% w/v sodium borohydride. The calibration graphs were linear up to 30 ng ml -1 . The detection limits of the method based on three times the standard deviation of the blank were 24 and 3.9 ng l -1 for total mercury and inorganic mercury determination, respectively. The relative standard deviation was less than 1.5% for a 10 ng ml -1 mercury standard. As a means of checking method performance, deionized water and pond water samples were spiked with methylmercury and inorganic mercury; quantitative recovery for total mercury and inorganic mercury was obtained. The accuracy of the method was verified by analyzing alkaline and acid extracts of five biological and sediment reference materials. Microwave-assisted extraction procedures resulted in higher concentrations of recovered mercury species, lower matrix interference with mercury determination and less time involved in sample treatment than conventional extraction procedures. The standard addition method was only needed for calibration when biological samples were analyzed. The detection limits were in the range of 1.2-19 and 6.6-18 ng g -1 in biological and sediment samples for inorganic mercury and total mercury determination, respectively

  19. 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]+.

  20. Rotational disorder in lithium borohydride

    NARCIS (Netherlands)

    Remhof, Arndt; Yan, Yigang; Embs, Jan Peter; Sakai, Victoria Garcia; Nale, Angeloclaudio; de Jongh, Petra; Lodziana, Zbigniew; Zuettel, Andreas

    2015-01-01

    LiBH4 has been discussed as a promising hydrogen storage material and as a solid-state electrolyte in lithiumion batteries. It contains 18.5 wt% hydrogen and undergoes a structural phase transition at 381K which is associated with a large increase in rotational disorder of the [BH4](-) anion and the

  1. Electrochemical oxidation of ethanol using PtRh/C electrocatalysts in alkaline medium and synthesized by sodium borohydride and alcohol reduction; Oxidação eletroquímica do etanol utilizando eletrocatalisadores PtRh/C em meio alcalino e sintetizados via borohidreto de sódio e redução por álcool

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, Eric Hossein

    2017-07-01

    PtRh/C were prepared by the following atomic proportions: (100,0), (0,100), (90,10), (70,30) and (50,50). The methods employed in the synthesis of these materials were reduction by sodium borohydride and reduction by alcohol. The metal salts used were H{sub 2}PtCl{sub 6}3•6H{sub 2}0 and (RhNO{sub 3}){sub 3}, the support used was Carbon black XC72 and the bulk metal composition was 20% and 80% of support. The electrocatalysts were characterized by Energy Dispersive X-ray spectroscopy, X-ray diffraction and Transmission electron microscopy. The ethanol electrochemical oxidation mechanism was investigated by in situ Fourier Transform Infrared Spectroscopy couple to an Attenuated Total Reflection technique. The electrocatalytic activity were evaluated by Cyclic Voltammetry, Linear Sweep Voltammetry and Chronoamperometry techniques. The Fuel Cells tests were made in a single direct alcohol fuel cell with alkaline membrane. The working electrodes were prepared by a thin porous coating technique. X-ray diffraction allowed to verify metallic alloys, segregate phases and to calculate the percentage of metallic alloys. It was else possible to identify crystallographic phases. Infrared Spectroscopy allowed to verify that the electrochemical oxidation of ethanol was carried out by an incomplete mechanism. PtRh(70:30)/C prepared by sodium borohydride produced large amounts of carbon dioxide and acetaldehyde. Rh/C showed electrocatalytic activity when compared with other materials studied.

  2. Reduction of Aldehydes Using Sodium Borohydride under Ultrasonic Irradiation

    Directory of Open Access Journals (Sweden)

    Maulidan Firdaus

    2016-08-01

    Full Text Available A simple, energy efficient, and relatively quick synthetic procedure for the reduction of aldehydes under ultrasonic irradiation is reported. Satisfactorily isolated yields (71-96% were achieved confirming that the preparation of alcohol by aldehyde reduction is possible in green and sustainable fashion.

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

    Indian Academy of Sciences (India)

    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 ...

  4. 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

  5. Sodium borohydride reduction of aromatic carboxylic acids via ...

    Indian Academy of Sciences (India)

    -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.

  6. Sodium borohydride reduction of aromatic carboxylic acids via ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. 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 ...

  7. Synthesis of Magnesium Nickel Boride Aggregates via Borohydride Autogenous Pressure.

    Science.gov (United States)

    Shahbazi, Mahboobeh; Cathey, Henrietta E; Mackinnon, Ian D R

    2018-03-23

    We demonstrate synthesis of the ternary intermetallic MgNi₃B₂ using autogenous pressure from the reaction of NaBH₄ with Mg and Ni metal powder. The decomposition of NaBH₄ to H₂ and B₂H₆ commences at low temperatures in the presence of Mg and/or Ni and promotes formation of Ni-borides and MgNi₃B₂ with the increase in temperature. MgNi₃B₂ aggregates with Ni-boride cores are formed when the reaction temperature is >670 °C and autogenous pressure is >1.7 MPa. Morphologies and microstructures suggest that solid-gas and liquid-gas reactions are dominant mechanisms and that Ni-borides form at a lower temperature than MgNi₃B₂. Magnetic measurements of the core-shell MgNi₃B₂ aggregates are consistent with ferromagnetic behaviour in contrast to stoichiometric MgNi₃B₂ which is diamagnetic at room temperature.

  8. Near infrared magnetic circular dichroism of uranium borohydride, U(BH4)4

    International Nuclear Information System (INIS)

    Keiderling, T.A.; Schulz, W.C.

    1980-01-01

    The magnetic circular dichroism of U(BH 4 ) 4 in Hf(BH 4 ) 4 at low temperatures has been measured in the near. The A terms resulting can be interpreted to confirm the E symmetry ground state and three excited state assignments. (orig.)

  9. 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

  10. 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.

  11. 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.

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

    Science.gov (United States)

    Miyazaki, R.; Maekawa, H.; Takamura, H.

    2014-05-01

    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.

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

    OpenAIRE

    R. Miyazaki; H. Maekawa; H. Takamura

    2014-01-01

    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 ...

  14. Reactivity of [Cp*Mo(CO)3Me] with chalcogenated borohydrides Li ...

    Indian Academy of Sciences (India)

    Abstract. Reactivity of [Cp*Mo(CO)3Me], 1 with various chalcogenide ligands such as Li[BH2E3] and. Li[BH3EFc] (E = S, Se or Te; Fc = (C5H5-Fe-C5H4)) has been described. Room temperature reaction of 1 with Li[BH2E3] (E = S and Se) yielded metal chalcogenide complexes [Cp*Mo(CO)2(η2-S2CCH3)], 2 and.

  15. 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...

  16. Reactivity of [Cp*Mo(CO)3Me] with chalcogenated borohydrides Li ...

    Indian Academy of Sciences (India)

    All the compounds have been characterized by mass spectrometry, IR, multinuclear NMR spectroscopy and structures were unequivocally established by crystallographic analysis for compounds 2, 3 and 7. Keywords. Molybdenum; thioacetate; sulfur; borate; ferrocene. 1. Introduction. The chalcogen chemistry of transition ...

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

    Directory of Open Access Journals (Sweden)

    Constantino Mauricio Gomes

    1998-01-01

    Full Text Available In this paper we describe the reduction by NaBH4 of some cyclopentanones containing an oxygenated function at the side chain position beta to the carbonyl group, both in the presence and in the absence of CeCl3. Some suggestions for the rationalization of the results are discussed, considering the stereochemical course of the reactions.

  18. Laboratory Studies of Hydrogen Gas Generation Using the Cobalt Chloride Catalyzed Sodium Borohydride-Water Reaction

    Science.gov (United States)

    2015-07-01

    used. We believe that the chloramine in tap water and dissolved organics in seawater form complexes with the catalyst impeding its ability to...resulted in a very viscous sludge due to the precipitation of NaBO2 hydrate crystals, foaming, and reaction temperatures approaching 90 °C. We used...laced a hose connected to the outlet of the reaction vessel inside the cylinder from the bottom . As hydrogen gas is generated, it bubbles inside the

  19. 1,4-Dihydroxy fatty acids: Artifacts by reduction of di- and polyunsaturated fatty acids with sodium borohydride

    Science.gov (United States)

    Thiemt, Simone; Spiteller, Gerhard

    1997-01-01

    In an effort to detect lipid peroxidation products in human blood plasma, samples were treated with NaBH4 to reduce the reactive hydroperoxides to hydroxy compounds. After saponification of the lipids, the free fatty acid fraction obtained by extraction was methylated and separated by TLC. The fractions containing polar compounds were trimethylsilylated and subjected to gas chromatography-mass spectrometry (GC/MS). Mass spectra allowed us to detect previously unknown 1,4-dihydroxy fatty acids due to their typical fragmentation pattern. If the reduction was carried out with NaBD4 instead of NaBH4, incorporation of two deuterium atoms was observed (appropriate mass shift). The two oxygen atoms of the hydroxyl groups were incorporated from air as shown by an experiment in 18O2 atmosphere. The reaction required the presence of free acids, indicating that BH3 was liberated, added to a 1,4-pentadiene system, and finally produced 1,4-diols by air oxidation.

  20. Kinetics of sodium borohydride direct oxidation and oxygen reduction in sodium hydroxide electrolyte - Part II. O-2 reduction

    Czech Academy of Sciences Publication Activity Database

    Chatenet, M.; Micoud, F.; Roche, I.; Chainet, E.; Vondrák, Jiří

    2006-01-01

    Roč. 51, č. 25 (2006), s. 5452-5458 ISSN 0013-4686 Institutional research plan: CEZ:AV0Z40320502 Keywords : oxygen reduction reaction selectivity * platinum * silver Subject RIV: CA - Inorganic Chemistry Impact factor: 2.955, year: 2006

  1. Facile fabrication of gold coated nickel nanoarrays and its excellent catalytic performance towards sodium borohydride electro-oxidation

    Science.gov (United States)

    Ma, Xiaokun; Ye, Ke; Wang, Gang; Duan, Moyan; Cheng, Kui; Wang, Guiling; Cao, Dianxue

    2017-08-01

    Novel Au@Ni nanoarrays electrode is facilely obtained by firstly template-assisted electro-deposition of Ni nanowire arrays (NAs), followed by galvanostatic deposition of Au catalysts onto the Ni NAs without any conductive agents and binders. The Au@Ni NAs electrode shows a rough surface and fringe with the diameter of ∼90 nm, which assures a high utilization of Au catalysts and provides a large specific surface area. The elemental distribution of Ni mainly exists in the inner layer of a single Au@Ni nanowire with the diameter ∼56 nm, while the elemental distribution of Au catalysts merely appears in the outer layer to form the unique core-shell nanowire structure. The Au@Ni NAs electrode reveals excellent electrochemical property and desirable stability for catalyzing NaBH4 electro-oxidation in basic solutions. The Au@Ni NAs electrode in the 2.00 M NaOH and 0.24 M NaBH4 solution demonstrates an oxidation current density of 2.35 A mg-1 at -0.5 V (vs. Ag/AgCl), which is much higher than that of the noble metal catalysts previously reported, indicating that this material may be hopefully used as anodic catalysts for applying in fuel cells.

  2. Binuclear Copper(I Borohydride Complex Containing Bridging Bis(diphenylphosphino Methane Ligands: Polymorphic Structures of [(µ2-dppm2Cu2(η2-BH42] Dichloromethane Solvate

    Directory of Open Access Journals (Sweden)

    Natalia V. Belkova

    2017-10-01

    Full Text Available Bis(diphenylphosphinomethane copper(I tetrahydroborate was synthesized by ligands exchange in bis(triphenylphosphine copper(I tetrahydroborate, and characterized by XRD, FTIR, NMR spectroscopy. According to XRD the title compound has dimeric structure, [(μ2-dppm2Cu2(η2-BH42], and crystallizes as CH2Cl2 solvate in two polymorphic forms (orthorhombic, 1, and monoclinic, 2 The details of molecular geometry and the crystal-packing pattern in polymorphs were studied. The rare Twisted Boat-Boat conformation of the core Cu2P4C2 cycle in 1 is found being more stable than Boat-Boat conformation in 2.

  3. Anisotropic Mg Electrodeposition and Alloying with Ag-based Anodes from Non-Coordinating Mixed-Metal Borohydride Electrolytes for Mg Hybrid Batteries

    International Nuclear Information System (INIS)

    Wetzel, David J.; Malone, Marvin A.; Gewirth, Andrew A.; Nuzzo, Ralph G.

    2017-01-01

    A highly anisotropic electrodeposition was observed using the hybrid battery electrolyte Mg(BH 4 ) 2 with LiBH 4 in diglyme. At low overpotentials high aspect ratio platelet morphologies are observed with a strong fiber texture composed of a {10-10} and a {11-20} component, the first evidence of behavior of this kind in magnesium battery electrolytes. At high overpotentials the deposit aspect ratio is indistinguishable but the texture is shown to be primarily composed of a {11-20} fiber texture. The kinetic parameters relative to the relevant crystallographic faces are extracted from electron microscopy images and compared with the observed bulk rate extracted from the electrochemical data. The use of polycrystalline Ag foil substrates with little preferred orientation at the surface allowed highly polycrystalline nucleation at lower overpotentials than that of platinum, likely due to Ag alloying with Mg. Characterization using focused ion beam (FIB) cross-sections with Auger Electron Spectroscopy (AES) elemental analysis confirm that the deposits are primarily Mg although Mg‐Ag alloys of various compositions were observed. It is proposed that the orientation at slow rates of growth is due to the underlying kinetics of adatom diffusion on Mg and that higher rates diminish the phenomenon due to decreased time for adatom diffusion and instead are governed by the rates of adatom formation or more specifically the adatom vacancy formation on the different low-index planes of Mg.

  4. Systematic investigations on the reduction of 4-aryl-4-oxoesters to 1-aryl-1,4-butanediols with methanolic sodium borohydride

    Directory of Open Access Journals (Sweden)

    Subrata Kumar Chaudhuri

    2010-09-01

    Full Text Available 4-Aryl-4-oxoesters undergo facile reduction of both the keto and the ester groups with methanolic NaBH4 at room temperature to yield the corresponding 1-aryl-1,4-butanediols whereas 4-alkyl-4-oxoesters furnish the corresponding 1,4-butanolides via selective reduction of the keto moiety. Results of a detailed and systematic investigation of the reaction are described.

  5. Rare Earth Borohydrides—Crystal Structures and Thermal Properties

    Directory of Open Access Journals (Sweden)

    Christoph Frommen

    2017-12-01

    Full Text Available Rare earth (RE borohydrides have received considerable attention during the past ten years as possible hydrogen storage materials due to their relatively high gravimetric hydrogen density. This review illustrates the rich chemistry, structural diversity and thermal properties of borohydrides containing RE elements. In addition, it highlights the decomposition and rehydrogenation properties of composites containing RE-borohydrides, light-weight metal borohydrides such as LiBH4 and additives such as LiH.

  6. Process for synthesis of ammonia borane for bulk hydrogen storage

    Science.gov (United States)

    Autrey, S Thomas [West Richland, WA; Heldebrant, David J [Richland, WA; Linehan, John C [Richland, WA; Karkamkar, Abhijeet J [Richland, WA; Zheng, Feng [Richland, WA

    2011-03-01

    The present invention discloses new methods for synthesizing ammonia borane (NH.sub.3BH.sub.3, or AB). Ammonium borohydride (NH.sub.4BH.sub.4) is formed from the reaction of borohydride salts and ammonium salts in liquid ammonia. Ammonium borohydride is decomposed in an ether-based solvent that yields AB at a near quantitative yield. The AB product shows promise as a chemical hydrogen storage material for fuel cell powered applications.

  7. THE STEREOCHEMISTRY AND MECHANISM OF HYDRIDE REDUCTIONS OF CYCLOHEXENE OXIDES.

    Science.gov (United States)

    HYDRIDES, *OXIDATION REDUCTION REACTIONS), (* CYCLOHEXANOLS , SYNTHESIS (CHEMISTRY)), (*STEREOCHEMISTRY, CYCLOHEXANES), (*BOROHYDRIDES, REDUCTION...CHEMISTRY)), DIBORANES, OXYGEN HETEROCYCLIC COMPOUNDS, CYCLOHEXANONES, CYCLOHEXENES , MOLECULAR ISOMERISM, ORGANIC SOLVENTS, GAS CHROMATOGRAPHY

  8. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct ...

    Indian Academy of Sciences (India)

    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 ...

  9. Reação da cânfora com boroidreto de sódio: uma estratégia para o estudo da estereoquímica da reação de redução Reaction of camphor with sodium borohydride: a strategy to introduce the stereochemical issues of a reduction reaction

    Directory of Open Access Journals (Sweden)

    Péricles B. Alves

    2010-01-01

    Full Text Available Reduction of camphor to a mixture of borneol and isoborneol was performed using NaBH4 as the reducing agent under suitable conditions. Although more effective reduction was accomplished using toxic methanol, an alternative non-toxic ethanolic system is described. This experiment is important to introduce undergraduate students in reductive procedures, and can be used to show details on stereoselective procedures on carbonyl moieties (facial diastereoselectivity, Bürgi-Dunitz trajectory, diastereomeric excess.

  10. Recycling of chemical hydrogen storage materials

    International Nuclear Information System (INIS)

    Lo, C.F.; Davis, B.R.; Karan, K.

    2004-01-01

    'Full text:' Light weight chemical hydrides such as sodium borohydride (NaBH4) and lithium borohydride (LiBH4) are promising hydrogen storage materials. They offer several advantages including high volumetric storage density, safe storage, practical storage and operating condition, controlled and rapid hydrogen release kinetics in alkaline aqueous media in the presence of catalysts. In addition, borate or borax, the reaction by-product, is environmentally friendly and can be directly disposed or recycled. One technical barrier for utilizing borohydrides as hydrogen storage material is their high production cost. Sodium borohydride currently costs $90 per kg while lithium borohydride costs $8000 per kg. For commercialization, new and improved technology to manufacture borohydrides must be developed - preferably by recycling borates. We are investigating different inorganic recycling routes for regenerating borohydrides from borates. In this paper, the results of a chlorination-based recycling route, incorporating multi-step reactions, will be discussed. Experiments were conducted to establish the efficiency of various steps of the selected regeneration process. The yields of desired products as a function of reaction temperature and composition were obtained from multi-phase batch reactor. Separation efficiency of desired product was also determined. The results obtained so far appear to be promising. (author)

  11. 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.

  12. Development of 3-methoxy-4-benzyloxybenzyl alcohol (MBBA) resin ...

    Indian Academy of Sciences (India)

    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 ...

  13. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    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 ...

  14. United States Military Academy: 25 Years of Enlightening Research. 2012 Program Review

    Science.gov (United States)

    2012-01-01

    Jasco V-670 UV/Vis Spectrometer. Borohydride Stabilized Ag Colloidal Synthesis All glassware was cleaned using a 4:1 H2SO4:30 % H2O2 solution...prior to colloid synthesis . Borohydride stabilized particles were prepared using a slightly modified procedure originally described by Cermakova et...element identification included energetics like NaNO3, RDX, PETN, and HMX, interferants like caffeine, aspirin finger skin and finger oil, and the

  15. Solid-state rechargeable magnesium battery

    Science.gov (United States)

    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.

  16. Final Technical Report for GO15056 Millennium Cell: Development of an Advanced Chemical Hydrogen Storage and Generation System

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Oscar [Millennium Cell Inc., Eatontown, NJ (United States)

    2017-02-22

    The objectives of this project are to increase system storage capacity by improving hydrogen generation from concentrated sodium borohydride, with emphasis on reactor and system engineering; to complete a conceptual system design based on sodium borohydride that will include key technology improvements to enable a hydrogen fuel system that will meet the systembased storage capacity of 1.2 kWh/L (36 g H2/L) and 1.5 kWh/kg (45 g H2/kg), by the end of FY 2007; and to utilize engineering expertise to guide Center research in both off-board chemical hydride regeneration and on-board hydrogen generation systems.

  17. Free radical-mediated hydroxymethylation using CO and HCHO.

    Science.gov (United States)

    Kawamoto, Takuji; Ryu, Ilhyong

    2012-01-01

    Tin-free radical hydroxymethylations of haloalkanes using CO and HCHO as a C1 unit proceed efficiently in the presence of borohydrides as radical mediators. In the approach using CO, the formation of aldehydes by radical carbonylation and their subsequent reduction by hydrides lead to alcohols. On the other hand, the use of formaldehyde is more straightforward, in which the key reaction is alkyl radical addition to formaldehyde to give alkoxy radical, which abstracts hydrogen from borohydride reagents. The cascade sequences were observed in the reaction of cholesteryl bromide with HCHO, which displays the diverse applications of HCHO in radical chemistry.

  18. 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...

  19. Carbon supported Pd-Ni and Pd-Ru-Ni nanocatalysts for the alkaline direct ethanol fuel cell (DEFC)

    CSIR Research Space (South Africa)

    Mathe, MK

    2011-08-01

    Full Text Available Carbon supported Pd-Ni and Pd-Ru-Ni nanocatalysts were prepared by the chemical reduction method, using sodium borohydride and ethylene glycol mixture as the reducing agent. The catalytic activity towards ethanol electro-oxidation in alkaline medium...

  20. Efficient synthesis of B-alkylated oxazaborolidines derived from ephedrine and norephedrine.

    Science.gov (United States)

    Ortiz-Marciales, Margarita; González, Eduvigis; De Jesús, Melvin; Espinosa, Sandraliz; Correa, Wildeliz; Martínez, Johanna; Figueroa, Ruth

    2003-09-18

    [reaction: see text] Representative B-butyl- and B-methyl-1,3,2-oxazaborolidines derived from ephedrine and norephedrine were prepared in good yield and excellent purity by one-pot treatment of B-H oxazaborolidines with the corresponding organolithium reagent and subsequent hydrolysis of the cyclic borohydride intermediate with anhydrous ammonium chloride.

  1. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Volume 121 Issue 5 September 2009 pp 647-654. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells · N A Choudhury S K Prashant S .... Photocatalytic properties of KBiO3 and LiBiO3 with tunnel structures · Rajalakshmi Ramachandran M Sathiya K Ramesha A S Prakash Giridhar Madras ...

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

    Directory of Open Access Journals (Sweden)

    Son-Jong Hwang

    2011-12-01

    Full Text Available Solid state NMR is widely applied in studies of solid state chemistries for hydrogen storage reactions. Use of 11B MAS NMR in studies of metal borohydrides (BH4 is mainly focused, revisiting the issue of dodecaborane formation and observation of 11B{1H} Nuclear Overhauser Effect.

  3. Hydrogen Liberation from Gaseous 2-Bora-1,3-diazacycloalkanium Cations

    NARCIS (Netherlands)

    Bendo, J.-A.; Martens, J.; Berden, G.; Oomens, J.; Morton, T.H.

    2017-01-01

    Evidence is presented for cyclization to yield 2-bora-1,3-diazacycloalkanium cations in the gas phase. While the neutral compounds in solution and solid phase are known to possess an acyclic structure (as revealed by X-ray diffraction), the gaseous cations (from which borohydride BH4– ion has been

  4. Hydrogen Liberation from Gaseous 2-Bora-1,3-diazacycloalkanium Cations.

    NARCIS (Netherlands)

    Bendo, J.A.; Martens, J.K.; Berden, G.; Oomens, J.; Morton, T.H.

    2017-01-01

    Evidence is presented for cyclization to yield 2-bora-1,3-diazacycloalkanium cations in the gas phase. While the neutral compounds in solution and solid phase are known to possess an acyclic structure (as revealed by X-ray diffraction), the gaseous cations (from which borohydride BH4(-) ion has been

  5. 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

  6. Effect of size of copper nanoparticles on its catalytic behaviour in ...

    Indian Academy of Sciences (India)

    WINTEC

    reduction of cupric salt solution using sodium borohydride in the presence of capping agent. In a typical set, 10 ml ... ammonium chloride followed by 2⋅5 ml of dichloro- methane which separated two layers with the .... nation and the formation of the aryl–aryl carbon bond. 4. Conclusions. In this paper, we have described a ...

  7. Synthesis of Indoles: Tetrahydropyrazino[1,2-a]indole-1,4-dione and ...

    African Journals Online (AJOL)

    NJD

    Indole compounds 7 and 9 were further treated, separately, with lithium aluminium hydride, sodium borohydride, lithium hydroxide monohydrate and butyl lithium to yield 2-substituted indoles10–13. KEYWORDS. Indoles, piperazine-2,5-diones, arylaldehydes, 1:1 adducts, 2:1 adducts. 1. Introduction. Piperazine-2,5-dione ...

  8. Tailoring of optical and electrical properties of PMMA by ...

    Indian Academy of Sciences (India)

    Silver–poly(methyl methacrylate) (Ag–PMMA) nanocomposite films were prepared via ex situ chemical routeby employing sodium borohydride (NaBH 4 ) as a reducing agent. In this study, PVP-stabilized Ag nanoparticles were prepared and mixed with PMMA solution. Optical and structural characterizations of resulting ...

  9. Untitled

    African Journals Online (AJOL)

    The reaction of mercaptomethyleiminium salts with sodium borohydride is used to synthesize alkylamine boranes in moderate to good yields. ... instrument was used for ir, spectra run as nujol mulls. All melting points (uncorrected) were ... cooled in ice-salt-water mixture. Thiobenzdimethylamide methiodide (X=H. Equation 2 ...

  10. Synthesis and characterization of stable aqueous dispersions of ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... 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 ...

  11. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. P Sridhar. Articles written in Journal of Chemical Sciences. Volume 121 Issue 5 September 2009 pp 647-654. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells · N A Choudhury S K Prashant S Pitchumani P Sridhar A K Shukla.

  12. S K Prashant

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. S K Prashant. Articles written in Journal of Chemical Sciences. Volume 121 Issue 5 September 2009 pp 647-654. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells · N A Choudhury S K Prashant S Pitchumani P Sridhar A K Shukla.

  13. A comprehensive study on the effect of Ru addition to Pt electrodes ...

    Indian Academy of Sciences (India)

    A comprehensive study on the effect of Ru addition to Pt electrodes for direct ethanol fuel cell ... Catalysis Volume 32 Issue 6 December 2009 pp 643-652 ... Abstract. The electro-oxidation of ethanol was studied over nanosized Pt and different compositions of PtRu catalysts synthesized by the borohydride reduction method.

  14. Synthesis of Indoles: Tetrahydropyrazino[1,2-a]indole-1,4-dione and ...

    African Journals Online (AJOL)

    ... and 2:1 (4–6) arylmethylenepiperazine-2,5-diones in above average yields. The halo-derivatives, 1, 4 and 5 were cyclized to pyrazino[1,2-a]indoles, 7–9, using copper bronze. Indole compounds 7 and 9 were further treated, separately, with lithium aluminium hydride, sodium borohydride, lithium hydroxide monohydrate ...

  15. Recent Developments in the Field of Energetic Ionic Liquids

    Science.gov (United States)

    2014-10-07

    a shift towards investigating hydride -based anions. In parallel, searching for the ultimate green rocket fuel alternative, Schneider and co...performance, they utilised an aluminum borohydride anionic complex, taking advantage of the large combustion energies of these light nontoxic metals...while simultaneously providing a large and dense hydride content. This 15 anion was coupled with a trihexyltetradecylphosphonium cation, which would

  16. Chapter 20 (Part 1): Oxidation and Reduction Reactions

    OpenAIRE

    Christiansen, Mike A

    2012-01-01

    In this video I'll teach you about several oxidation and reduction reactions, which include carbonyl reductions using sodium borohydride, lithium aluminum hydride, and DIBAL-H (diisobutyl aluminum hydride), as well oxidations using chromium reagents and the Baeyer-Villiger oxidation reaction. --Dr. Mike Christiansen from Utah State University

  17. Leaching and antimicrobial properties of silver nanoparticles loaded onto natural zeolite clinoptilolite by ion exchange and wet impregnation

    CSIR Research Space (South Africa)

    Missengue, RNM

    2015-11-01

    Full Text Available This study aimed to compare the leaching and antimicrobial properties of silver that was loaded onto the natural zeolite clinoptilolite by ion exchange and wet impregnation. Silver ions were reduced using sodium borohydride (NaBH(sub4...

  18. One-pot Reductive Amination of Carbonyl Compounds with NaBH4 ...

    Indian Academy of Sciences (India)

    Abstract. An efficient one-pot procedure for the direct reductive amination of aldehyde and ketones was achieved in the presence of sodium borohydride by using B(OSO3H)3/SiO2(SBSA) as the reusable solid cat- alyst in acetonitrile and solvent-free conditions. Both aromatic and aliphatic aldehyde reacted well to give the.

  19. Synthesis and characterization of stable aqueous dispersions of ...

    Indian Academy of Sciences (India)

    Abstract. 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 ...

  20. Carbon supported Pd-Sn and Pd-Ru-Sn nanocatalysts for ethanol electro-oxidation in alkaline medium

    CSIR Research Space (South Africa)

    Modibedi, RM

    2011-04-01

    Full Text Available Carbon supported Pd-Sn and Pd-Ru-Sn nanocatalysts were prepared by the chemical reduction method, using sodium borohydride and ethylene glycol mixture as the reducing agent. The catalytic activity towards ethanol electro-oxidation in alkaline medium...

  1. Cobalt nanoparticles as reusable catalysts for reduction of 4 ...

    Indian Academy of Sciences (India)

    Abstract. Facile reduction of p-nitrophenol to p-aminophenol by sodium borohydride catalysed by cobalt nanopar- ticles (CoNPs) has been discussed. A simple approach has been made to synthesize highly active and ordered structures of CoNPs. The air-stable nanoparticles were prepared from cobalt sulphate using ...

  2. Cross-Course Collaboration in the Undergraduate Chemistry Curriculum: Isotopic Labeling with Sodium Borodeuteride in the Introductory Organic Chemistry Laboratory

    Science.gov (United States)

    Kjonaas, Richard A.; Fitch, Richard W.; Noll, Robert J.

    2017-01-01

    A microscale isotopic labeling experiment is described for the introductory organic chemistry laboratory course wherein half of the students use sodium borohydride (NaBH[subscript 4]) and the other half use sodium borodeuteride (NaBD[subscript 4]) to reduce acetophenone to 1-phenylethanol and then compare spectral data. The cost is reasonable, and…

  3. Nickel cobalt oxide hollow nanosponges as advanced electrocatalysts for the oxygen evolution reaction

    OpenAIRE

    Zhu, Chengzhou; Wen, Dan; Leubner, Susanne; Oschatz, Martin; Liu, Wei; Holzschuh, Matthias; Simón, Frank M.; Kaskel, Stefan; Eychmüller, Alexander

    2015-01-01

    A class of novel nickel cobalt oxide hollow nanosponges were synthesized through a sodium borohydride reduction strategy. Due to their porous and hollow nanostructures, and synergetic effects between their components, the optimized nickel cobalt oxide nanosponges exhibited excellent catalytic activity towards oxygen evolution reaction.

  4. Convenient Reduction of Carbonyl Compounds to their ...

    African Journals Online (AJOL)

    Sodium borohydride (0.4–1.5 equivalents) in the presence of ammonium oxalate (0.2 equivalents) reduces varieties of organic carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α,β-unsaturated carbonyl compounds to their corresponding alcohols. Reduction reactions were carried out in ...

  5. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. S Pitchumani. Articles written in Journal of Chemical Sciences. Volume 121 Issue 5 September 2009 pp 647-654. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells · N A Choudhury S K Prashant S Pitchumani P Sridhar A K Shukla.

  6. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. KOUSHIK SAHA. Articles written in Journal of Chemical Sciences. Volume 128 Issue 7 July 2016 pp 1025-1032 Regular Article. Reactivity of [Cp*Mo(CO)₃Me] with chalcogenated borohydrides Li[BH₂E₃] and Li[BH₃EFc] (Cp* = (ŋ⁵-C₅Me₅); E = S, Se or Te; ...

  7. Structure of three acidic O-linked carbohydrate chains of porcine zona pellucida glycoproteins

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Hokke, C.H.; Damm, J.B.L.; Kamerling, J.P.

    1993-01-01

    Structural analysis by ID and 2D 1H NMR spectroscopy of three acidic O-linked oligosaccharide alditols, released from porcine zona pellucida glycoproteins by alkaline borohydride treatment, afforded the following structures: Gal beta l-4(6SO4-)GlcNAc beta l-3Gal beta l-4GlcNAc beta 1-3Gal beta

  8. Development of 3-methoxy-4-benzyloxybenzyl alcohol (MBBA) resin ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 3-Methoxy-4-benzyloxybenzyl alcohol (MBBA) resin was synthesized by a two-step se- quence 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 ...

  9. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. ANAMIKA PAUL. Articles written in Journal of Chemical Sciences. Volume 128 Issue 7 July 2016 pp 1025-1032 Regular Article. Reactivity of [Cp*Mo(CO)₃Me] with chalcogenated borohydrides Li[BH₂E₃] and Li[BH₃EFc] (Cp* = (ŋ⁵-C₅Me₅); E = S, Se or Te; ...

  10. Thio-sugars. IV: Design and synthesis of S-linked fucoside analogs as a new class of alpha-L-fucosidase inhibitors.

    Science.gov (United States)

    Witczak, Z J; Boryczewski, D

    1998-11-17

    alpha-1-Thio-L-fucose derivative 4 and 5 as new alpha-fucosidase inhibitors (K1 = 4.6, and 5.9 microM) have been synthesized in three steps by base catalyzed coupling with bromonitromethane followed by reduction of the nitro group with sodium borohydride/cobalt chloride complex and acetylation.

  11. FT–Raman investigation of bleaching of spruce thermomechanical pulp

    Science.gov (United States)

    U.P. Agarwal; L.L. Landucci

    2004-01-01

    Spruce thermomechanical pulp was bleached initially by alkaline hydrogen peroxide and then by sodium dithionite and sodium borohydride. Near-infrared Fourier-transform–Raman spectroscopy revealed that spectral differences were due primarily to coniferaldehyde and p-quinone structures in lignin, new direct evidence that bleaching removes p-quinone structures. In...

  12. Synthesis of tritiated sex pheromones of the processionary moth Thaumetopoea pityocampa and the Egyptian armyworm Spodoptera littoralis

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, Angel; Feixas, Joan [CID (CDIC), Biological Organic Chemistry Dept., Barcelona (Spain)

    1996-10-01

    Synthesis of tritiated sex phenomones of the processionary moth Thaumetopoea pityocampa and the Egyptian armyworm Spodoptera littoralis has been accomplished by a simple route involving tritiated sodium borohydride reduction of the corresponding aldehyde followed by acetylation of the resulting radiolabelled alcohol. The process occurs with high chemical and radiochemical yields and the compounds have been used in pheromone catabolism studies. (author).

  13. 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…

  14. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Facile reduction of p-nitrophenol to p-aminophenol by sodium borohydride catalysed by cobalt nanoparticles (CoNPs) has been discussed. A simple approach has been made to synthesize highly active and ordered structures of CoNPs. The air-stable nanoparticles were prepared from cobalt sulphate using tetrabutyl ...

  15. S Pitchumani

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. S Pitchumani. Articles written in Journal of Chemical Sciences. Volume 121 Issue 5 September 2009 pp 647-654. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells · N A Choudhury S K Prashant S Pitchumani P Sridhar A K Shukla.

  16. 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

  17. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. 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 gold- plated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium boro- hydride as fuel and ...

  18. SYNTHESIS AND CHARACTERIZATION OF CdTe QUANTUM ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT. L-Cysteine (Cys)-capped CdTe quantum dots (QDs) were prepared when sodium tellurite worked as a tellurium source and sodium borohydride acted as a reductant. The influences of various experimental variables, including pH values, Cd/Te and Cd/Cys molar ratios, on the photoluminescence (PL) quantum ...

  19. Download this PDF file

    African Journals Online (AJOL)

    quinoxalin-2-one (5), was identical with that prepared from the D-erythro analog. The IH NMR spectrum of 5 showed two NH protons (6 11.20 and 12.50) and an aldehydic proton (6 9.58). Reduction of 5 with sodium borohydride afforded ...

  20. Effects from additives on deacetylation of chitin; Efeito de aditivos na desacetilacao de quitina

    Energy Technology Data Exchange (ETDEWEB)

    Campana Filho, Sergio P.; Signini, Roberta [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: scampana@iqsc.sc.usp.br

    2001-12-01

    Deacetylation reactions of commercial chitin were carried out in aqueous sodium hydroxide solution at 115 deg C for 6 hours. The effect from additives (sodium borohydride or anthraquinone) and of bubbling inert gas (nitrogen or argon) on the characteristics of deacetylated samples were evaluated. Average degrees of acetylation and intrinsic viscosity were determined by {sup 1}H NMR spectroscopy and capillary viscometry, respectively. X-ray diffraction was employed to evaluate changes in crystallinity and infrared spectroscopy was used to monitor structural changes due to deacetylation. The bubbling of inert gas during the deacetylation reaction resulted in more crystalline samples of chitosan. Deacetylation carried out without any additive produced slightly more deacetylated chitosan but they were severely depolymerized. The depolymerization process was much less important when sodium borohydride was added to the reaction medium but the addition of anthraquinone and the bubbling of nitrogen, or argon, did not have any effect, this suggests that oxygen is not required for depolymerization. (author)

  1. Effects from additives on deacetylation of chitin

    International Nuclear Information System (INIS)

    Campana Filho, Sergio P.; Signini, Roberta

    2001-01-01

    Deacetylation reactions of commercial chitin were carried out in aqueous sodium hydroxide solution at 115 deg C for 6 hours. The effect from additives (sodium borohydride or anthraquinone) and of bubbling inert gas (nitrogen or argon) on the characteristics of deacetylated samples were evaluated. Average degrees of acetylation and intrinsic viscosity were determined by 1 H NMR spectroscopy and capillary viscometry, respectively. X-ray diffraction was employed to evaluate changes in crystallinity and infrared spectroscopy was used to monitor structural changes due to deacetylation. The bubbling of inert gas during the deacetylation reaction resulted in more crystalline samples of chitosan. Deacetylation carried out without any additive produced slightly more deacetylated chitosan but they were severely depolymerized. The depolymerization process was much less important when sodium borohydride was added to the reaction medium but the addition of anthraquinone and the bubbling of nitrogen, or argon, did not have any effect, this suggests that oxygen is not required for depolymerization. (author)

  2. 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.

  3. 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, 2,6-did......,6-dideoxy-L-arabino-hexose, and 2-deoxy-D-erythropentose can be prepared from D-galactose, L-rhamnose, and D-arabinose, respectively.......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...

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

    Science.gov (United States)

    Ley, Morten B.; Meggouh, Mariem; Moury, Romain; Peinecke, Kateryna; Felderhoff, Michael

    2015-01-01

    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. PMID:28793541

  5. Synthesis of bicyclic alkaloids from the iridoid antirrhinoside

    DEFF Research Database (Denmark)

    Frederiksen, Signe Maria

    alkaloid was prepared from antirrhinoside by means of an enzymatic cleavage to afford the aglucone, followed by a double reductive amination with benzylamine hydrochloride and sodium cyanoborohydride. The resulting piperidine was modified by opening of the epoxide on the cyclopropane ring by azide......-analogue and enzymatically cleaved by b-glucosidase to afford the 3,4-dihydro-5,6-O-isopropylidene antirrhinoside aglucone. Unfortunately, the subsequent sodium borohydride reduction of the aglucone proved difficult, affording a mixture of the expected diol and a product with a 2-oxo[3.2.1]octane framework. The latter....... 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...

  6. Lipopolysaccharide Antigens of Pseudomonas aeruginosa and Design of Novel Vaccines.

    Science.gov (United States)

    1987-09-01

    the alditols and subsequent acetylation, showed the presence, by g.l.c.-m.s. procedures, of three sugars, namely rhamnoze, glucose, and quinovosamine...identified by their fragmentation patterns of the methylated alditol acetates by g.l.c.-m.s.; 1,5-di-_O-acetyl-6-deoxy-2,3,4- 12 IN.- tri...atoms, and a uronic acid. Smith degradation of the alditol obtained by borohydride reduction of the disaccharide, by periodate oxidation, and further

  7. Role of Ti doping and Al and B vacancies in the dehydrogenation of ...

    Indian Academy of Sciences (India)

    Å). (b) Electron density around the Al(BH4)3 unit (Isosurface value: 0.039 e.Å. −3. ). (c) Molecular structure of Al(BH4)3 with four pairs (HA, HB, HC and HD) of hydrogen atoms. (d) Total and partial density of states of pure aluminium borohydride. The Fermi level is set to zero and indicated by a black-dashed line.

  8. Synthesis of α-nitroalkyl- and α-perfluoroalkylamines with use of reduction of perfluoroalkylnitrile condensation products with carbanions in NaBH4-CH3COOH system

    International Nuclear Information System (INIS)

    Ajzikovich, A.Ya.; Korotaev, V.Yu.; Sagajdak, V.A.

    1998-01-01

    Method for synthesis of α-perfluoroalkylamines through condensation of nitriles of perfluorocarbon acids with carbon ions and subsequent reduction of reaction products by the sodium borohydride-acetic acid system with the yield of 14-78 % is developed. Reduction of ethyl ester of 3-amino-4,4,4-trifluor-2-cyano-2-butene acid under similar conditions results in reduction deamination - ethyl ester of 4,4,4-trifluoro-2-cyano-butane acid [ru

  9. Investigating Catalytic Properties of Composite Nanoparticle Assemblies

    Science.gov (United States)

    2001-11-01

    phase transfer agent (tetraoctylammonium chloride), and reduced by sodium borohydride in the presence of decanethiols (DT). The reaction was allowed...for 5 minutes in a 10- M K’PtCl6 solution . The activation of the film involved thermal activation at 300 "C (instead of electrochemical polarization...CO and MeOH oxidation in alkaline solution . This assessment may prove extremely important as 430 we develop high performance fuel cell catalysts that

  10. Graphene templated Directional Growth of an Inorganic Nanowire

    Science.gov (United States)

    2015-03-23

    Angew. Chem. Int. Ed. 45, 3611–3613 (2006). 10. Fukushima, T. et al. Molecular ordering of organic molten salts triggered by single-walled carbon... chloride (AuCl3, 99 %, Aldrich), didodecyldimethylammonium bromide (DDAB, Fluka), sodium borohydride (NaBH4, 99.99 %, Aldrich), and dodecanethiol...DDTh, > 98 %, Aldrich) are purchased and used without further purification. 51 mg of gold chloride and 0.173 g of DDAB are dissolved by sonication in

  11. Fulltext PDF

    Indian Academy of Sciences (India)

    −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. ... port properties in addition to being stable and active in a ..... Devi P S and Rao M S 1992 J. Solid State Chem.

  12. $sup 3$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)

  13. Download this PDF file

    African Journals Online (AJOL)

    conditions to give the steroidal indoxyl 17B-hydroxy-1-(3'-oxoindan-2'-yliden)-3- nor-1,2-secoandrostan-3-0ic acid (I) which on ... dione (II). Reduction of I with sodium borohydride gives the indole 17 B-hydroxy-l-. (indol-2'-yl)-3-nor-l, .... aldehyde induces the aldol intermediate to react preferentially by an intramolecular ...

  14. Project Squid. A Program of Fundamental Research on Liquid Rocket and Pulse Jet Propulsion for the Bureau of Aeronautics and the Office of Naval Research of the Navy Department

    Science.gov (United States)

    1948-01-01

    nitrogen, and the literature mentions the existence of beryllium hydride . After consulta- tion with the Brush Beryllium Company, it was decided...both peroxide and water. \\ The ignition of hydrocarbon-oxygen mixtures by addition of aluminium borohydride is discussed in Paper No. 33. It appears...experi- ments with lead ethyl are available; inorganic alkyls and hydrides have been shown to induce explosion. But there is need for

  15. Special Topic 2D: Reduction & Organometallic

    OpenAIRE

    Christiansen, Mike A

    2012-01-01

    The purpose of this video is to help second-year organic chemistry students review the concepts and questions that most frequently appear on standardized entrance exams, like the MCAT, DAT, PCAT, and GRE. In this video I'll review the following reduction reactions: hydrogenations of alkenes and alkynes, reductive amination, and Clemmensen and Wolff-Kishner reductions. I'll also teach you the following organometallic reactions: Grignard reactions; hydride (sodium borohydride, lithium aluminum ...

  16. Chapter 18 (Part 2): Aldehydes & Ketones

    OpenAIRE

    Christiansen, Mike A

    2012-01-01

    In this video I'll teach you about what happens when we add acetylide, cyanide, and Grignard reagents to aldehydes and ketones. I also provide in-depth coverage on the reaction of aldehydes, ketones, carboxylic acids, esters, amides, and acyl (acid) chlorides with sodium borohydride (NaBH4), lithium aluminum hydride (LiAlH4), and DIBAL-H (or "diisobutyl aluminum hydride). --Dr. Mike Christiansen from Utah State University

  17. A Twist on Facial Selectivity of Hydride Reductions of Cyclic Ketones: Twist-Boat Conformers in Cyclohexanone, Piperidone, and Tropinone Reactions

    OpenAIRE

    Neufeldt, Sharon R.; Jim?nez-Os?s, Gonzalo; Comins, Daniel L.; Houk, K. N.

    2014-01-01

    The role of twist-boat conformers of cyclohexanones in hydride reductions was explored. The hydride reductions of a cis-2,6-disubstituted N-acylpiperidone, an N-acyltropinone, and tert-butylcyclohexanone by lithium aluminum hydride and by a bulky borohydride reagent were investigated computationally and compared to experiment. Our results indicate that in certain cases, factors such as substrate conformation, nucleophile bulkiness, and remote steric features can affect stereoselectivity in wa...

  18. Sensitive method for the analysis of carbohydrates by gas chromatography of 3H-labeled alditol acetates

    International Nuclear Information System (INIS)

    Prehm, P.; Scheid, A.

    1978-01-01

    A highly sensitive method has been developed for the analysis of carbohydrates from glycoproteins or lipopolysaccharides. The method is based on labeling the carbohydrates with [ 3 H] sodium borohydride, acetylating the resulting alditols and separating them by gas chromatography. The gas effluent is fractionated by trapping on silicone-coated glass beads and the amount of radioactivity is determined. This permits the quantitation of as little as 0.2 nmoles monosaccharide with an accuracy of 10 to 15%. (Auth)

  19. Tunable Artificial Receptor as a Chemical Sensor for V- and G-agents

    Science.gov (United States)

    2012-06-01

    dried under vacuum to give a 90% yield. 3.2.4 Synthesis of Host-[2]Rotaxane Cyclophane 35 was neutralized with 2N sodium hydroxide ...gram GA Tabun GD Soman h hours HCl hydrochloric acid H2 hydrogen HPLC high pressure liquid chromatography...borohydride NaH sodium hydride NaOH sodium hydroxide NaN3 sodium azide Na2CO3 sodium carbonate Na2SO4 sodium sulfate

  20. 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.

  1. Butyltin compounds in biofilm and marine organisms from the Dona Paula Bay, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.

    aliquot of sea water sample (750 ml [millilitres]) was transferred to a clean teflon separatory funnel and 20 ml of dichloromethane, 15 ml of six per cent (w/v (weight/volume)) aqueous sodium borohydride and 100 ?l (microlitres) containing 129 ng... (nanograms) of the internal standard TPrT (tripropyltin Butylin compounds in biofilm and marine organisms 435 chloride) were added and the organotin compounds extracted. The organic lay ers were collected, dried using anhydrous sodium sulphate, filtered...

  2. 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.

  3. Procedures for the synthesis of ethylenediamine bisborane and ammonia borane

    Science.gov (United States)

    Ramachandran, Padi Veeraraghavan; Gagare, Pravin D.; Mistry, Hitesh; Biswas, Bidyut

    2017-01-03

    A method for synthesizing ammonia borane includes (a) preparing a reaction mixture in one or more solvents, the reaction mixture containing sodium borohydride, at least one ammonium salt, and ammonia; and (b) incubating the reaction mixture at temperatures between about 0.degree. C. to about room temperature in an ambient air environment under conditions sufficient to form ammonia borane. Methods for synthesizing ethylenediamine bisborane, and methods for dehydrogenation of ethylenediamine bisborane are also described.

  4. 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).

  5. Hydride generation-atomic absorption spectrometry for determination of trace arsenic in draining waste water of uranium hydrometallurgical plant

    International Nuclear Information System (INIS)

    Sun Suqing; Sun Shiying; Xue Jingxia

    1986-01-01

    The arsenate is reduced to the arsenite by potassium iodide-sulfourea in dilute sulphuric acid. Then the arsenite is reduced to arsine by sodium borohydride. The arsine carried into silica tube atomizer by nitrogen is atomized at 920 deg C and determined by the homemade atomic absorption instrument. It is shown that the sensitivity of the mentioned method is 0.2 ng/ml (1% absorption). The recovery is 88-103% and the relative standard deviation is ≤ 10%

  6. Amberlite IRA-400 Cl resin catalyzed synthesis of secondary amines and transformation into N-((1H-indol-3-yl (heteroaryl methyl-N-heteroaryl benzenamines and bis-indoles via multicomponent reaction

    Directory of Open Access Journals (Sweden)

    Gurusamy Harichandran

    2018-02-01

    Full Text Available A one-pot Amberlite IRA-400 Cl resin catalyzed the in-situ generation of imines from various aldehydes and primary amines followed by reduction with sodium borohydride affording corresponding secondary amines. The secondary amines thus obtained were utilized for the IRA-400 Cl resin catalyzed multicomponent synthesis of 3-aminoalkylated indoles using a number of aldehydes and indole. Mild condition, easy work-up, and environmentally benign nature of the synthetic strategy make it both practical and attractive.

  7. Compact solid source of hydrogen gas

    Science.gov (United States)

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester, Alan P.; Bell, Nelson S.

    2004-06-08

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  8. Synthesis of graphene platelets by chemical and electrochemical route

    Energy Technology Data Exchange (ETDEWEB)

    Ramachandran, Rajendran; Felix, Sathiyanathan [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Joshi, Girish M. [Materials Physics Division, School of Advanced Sciences, VIT University, Vellore 632014, Tamil Nadu (India); Raghupathy, Bala P.C., E-mail: balapraveen2000@yahoo.com [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Research and Advanced Engineering Division (Materials), Renault Nissan Technology and Business Center India (P) Ltd., Chennai, Tamil Nadu (India); Jeong, Soon Kwan, E-mail: jeongsk@kier.re.kr [Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Grace, Andrews Nirmala, E-mail: anirmalagrace@vit.ac.in [Centre for Nanotechnology Research, VIT University, Vellore 632014, Tamil Nadu (India); Climate Change Technology Research Division, Korea Institute of Energy Research, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)

    2013-10-15

    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. • NaBH{sub 4} 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.

  9. Synthesis of Pt/rGO catalysts with two different reducing agents and their methanol electrooxidation activity

    International Nuclear Information System (INIS)

    Vu, Thu Ha Thi; Tran, Thanh Thuy Thi; Le, Hong Ngan Thi; Tran, Lien Thi; Nguyen, Phuong Hoa Thi; Nguyen, Minh Dang; Quynh, Bui Ngoc

    2016-01-01

    Highlights: • Pt/rGO catalysts were successfully synthesized using either NaBH 4 or ethylene glycol. • Synthesis using NaBH 4 could improve electrocatalytic towards methanol oxidation of Pt/rGO catalyst. • 40%Pt/rGO synthesized using NaBH 4 showed the best electrocatalytic performance. - Abstract: The synthesis processes of Platinum (Pt) on reduced graphene oxide (rGO) catalysts from graphene oxide (GO) using two reducing agents including sodium borohydride and ethylene glycol is reported. Structure and morphology of Pt/rGO catalysts are characterized by X-ray powder diffraction, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrocatalytic methanol oxidation properties of these catalysts are evaluated by cyclic voltammetry and chronoamperometry. The results show that catalyst synthesized using sodium borohydride has a higher metallic Pt content and an improved catalytic performance in comparison to catalyst synthesized using ethylene glycol. Moreover, effect of Pt loading amount on electrocatalytic methanol oxidation performance of catalysts synthesized using sodium borohydride is systematically investigated. The optimal Pt loading amount on graphene is determined to be 40%.

  10. High utilization platinum deposition on single-walled carbon nanotubes as catalysts for direct methanol fuel cell

    International Nuclear Information System (INIS)

    Wang, J.J.; Yin, G.P.; Zhang, J.; Wang, Z.B.; Gao, Y.Z.

    2007-01-01

    This research aims to enhance the activity of Pt catalysts, thus to lower the loading of Pt metal in fuel cell. Highly dispersed platinum supported on single-walled carbon nanotubes (SWNTs) as catalyst was prepared by ion exchange method. The homemade Pt/SWNTs underwent a repetition of ion exchange and reduction process in order to achieve an increase of the metal loading. For comparison, the similar loading of Pt catalyst supported on carbon nanotubes was prepared by borohydride reduction method. The catalysts were characterized by using energy dispersive analysis of X-ray (EDAX), transmission electron micrograph (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectrum (XPS). Compared with the Pt/SWNTs catalyst prepared by borohydride method, higher Pt utilization was achieved on the SWNTs by ion exchange method. Furthermore, in comparison to the E-TEK 20 wt.% Pt/C catalyst with the support of carbon black, the results from electrochemical measurement indicated that the Pt/SWNTs prepared by ion exchange method displayed a higher catalytic activity for methanol oxidation and higher Pt utilization, while no significant increasing in the catalytic activity of the Pt/SWNTs catalyst obtained by borohydride method

  11. 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 borohy...... in the 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).......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...... borohydride can be modified by ball-milling with Al- and/or Ti-containing compounds. In this study, lithium alanate (LiAlH4), is used as an Al source. From careful examination of the ball-milled samples, it appears that LiBH4 remains unchanged during milling. The samples contain 100 nm diameter Al and/or Al...

  12. Synthesis of Pt/rGO catalysts with two different reducing agents and their methanol electrooxidation activity

    Energy Technology Data Exchange (ETDEWEB)

    Vu, Thu Ha Thi, E-mail: ptntd2004@yahoo.fr [Key Laboratory for Petrochemical and Refinery Technologies, 2 Pham Ngu Lao street, Hanoi (Viet Nam); Tran, Thanh Thuy Thi, E-mail: tranthithanhthuygl@gmail.com [Key Laboratory for Petrochemical and Refinery Technologies, 2 Pham Ngu Lao street, Hanoi (Viet Nam); Le, Hong Ngan Thi; Tran, Lien Thi; Nguyen, Phuong Hoa Thi; Nguyen, Minh Dang [Key Laboratory for Petrochemical and Refinery Technologies, 2 Pham Ngu Lao street, Hanoi (Viet Nam); Quynh, Bui Ngoc [Institut de recherches sur la catalyse et l’environnement de Lyon, UMR5256, 2 avenue Albert Einstein, 69626 Villeurbanne cedex (France)

    2016-01-15

    Highlights: • Pt/rGO catalysts were successfully synthesized using either NaBH{sub 4} or ethylene glycol. • Synthesis using NaBH{sub 4} could improve electrocatalytic towards methanol oxidation of Pt/rGO catalyst. • 40%Pt/rGO synthesized using NaBH{sub 4} showed the best electrocatalytic performance. - Abstract: The synthesis processes of Platinum (Pt) on reduced graphene oxide (rGO) catalysts from graphene oxide (GO) using two reducing agents including sodium borohydride and ethylene glycol is reported. Structure and morphology of Pt/rGO catalysts are characterized by X-ray powder diffraction, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrocatalytic methanol oxidation properties of these catalysts are evaluated by cyclic voltammetry and chronoamperometry. The results show that catalyst synthesized using sodium borohydride has a higher metallic Pt content and an improved catalytic performance in comparison to catalyst synthesized using ethylene glycol. Moreover, effect of Pt loading amount on electrocatalytic methanol oxidation performance of catalysts synthesized using sodium borohydride is systematically investigated. The optimal Pt loading amount on graphene is determined to be 40%.

  13. 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.

  14. Observing reduction of 4-nitrobenzenthiol on gold nanoparticles in situ using surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Ren, Xiaoqian; Tan, Enzhong; Lang, Xiufeng; You, Tingting; Jiang, Li; Zhang, Hongyan; Yin, Penggang; Guo, Lin

    2013-09-14

    In this article, reduction of 4-nitrobenzenthiol (4-NBT) on Au nanoparticles (NPs) was characterized using surface-enhanced Raman scattering (SERS). Plasmon-driven chemical transformation from 4-NBT dimering into p,p'-dimercaptoazobenzene (DMAB) has been investigated on the surface of Au NPs. The laser power-dependent SERS spectra of 4-NBT on the surface of Au substrates were studied, and show that the laser power has an influence on the SERS signals of 4-NBT on Au NPs and production of DMAB by a plasmon-driven surface-catalyzed chemical reaction tends to be much easier under relative high laser power. Furthermore, we have used simple and efficient Au substrates (gold NPs with a size around 45 nm) exhibiting both catalytic properties and SERS activities to monitor the catalytic reaction of surface catalytic reaction process with borohydride solution. The experiments prove that the nitro-to-amino group conversion could be completed by borohydride at ambient conditions on Au substrates. Illuminated with high laser power, 4-NBT molecules and already formed DMAB molecules are further reduced into 4-aminobenzenthiol (4-ABT) by the addition of borohydride, While with low laser power 4-NBT molecules are transformed into 4-ABT with DMAB as the intermediate, which proves Au NPs are a mild and promising catalyst. Our studies might be helpful in extending the understanding of chemical reactions of 4-NBT and related research as well as providing a new strategy synthesis of azo dyes and anilines.

  15. Synthesis of graphene platelets by chemical and electrochemical route

    International Nuclear Information System (INIS)

    Ramachandran, Rajendran; Felix, Sathiyanathan; Joshi, Girish M.; Raghupathy, Bala P.C.; Jeong, Soon Kwan; Grace, Andrews Nirmala

    2013-01-01

    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. • NaBH 4 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

  16. Silver-coated monolithic columns for separation in radiopharmaceutical applications.

    Science.gov (United States)

    Sedlacek, Ondrej; Kucka, Jan; Svec, Frantisek; Hruby, Martin

    2014-04-01

    In this study, we demonstrate the preparation of a macroporous monolithic column containing anchored silver nanoparticles and its use for the elimination of excess radioiodine from the radiolabeled pharmaceutical. The poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was first functionalized with cystamine and the free thiol groups liberated by reaction with borohydride. In-house-prepared silver nanoparticles were then attached by interaction with the surface thiols. The deiodization process was demonstrated with the commonly used radiopharmaceutical m-iodobenzylguanidine labeled with radionuclide iodine-125. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. 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......-ray diffraction. Magnetic measurements of the saturation magnetization, coercivity, and remanence of the particles have been measured. The transition from the amorphous-to-crystalline state has been studied using differential scanning calorimetry (DSC) and thermomagnetometry up to a temperature of 450 °C (see Fig...

  18. 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

    1999-01-01

    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....

  19. Synthesis of [2,4-3H] 17β-dihydroequilin sulfate

    International Nuclear Information System (INIS)

    Bhavnani, B.R.

    1994-01-01

    [2,4- 3 H] 17β-dihydroequilin-3-sulfate ammonium salt suitable for in vivo pharmacokinetic studies was synthesized from [2,4- 3 H] equilin. Sulfation of [2,4- 3 H] equilin with pyridine-chlorosulfonic acid mixture gave in high yields [2,4- 3 H] equilin sulfate, which was then reduced with sodium borohydride to yield [2,4- 3 H] 17β-dihydroequilin sulfate. The reduction was sterospecific and no 17α-reduced products were formed. (author)

  20. Combination of hollow fluorescent carbon and gold nanoparticles: A super-catalyst

    Science.gov (United States)

    Santra, Kakali; Purkayastha, Pradipta

    2018-02-01

    Hollow fluorescent carbon nanoparticles (HFCNs) have been combined with gold nanoparticles (AuNPs) to produce a special catalyst. The catalytic properties of HFCNs and AuNPs were exploited to conceptualize the new catalytic functionality. The AuNP-embedded-HFCNs produced in situ were found to massively enhance the rate of reduction of 4-nitrophenol (a model reaction) in presence of sodium borohydride. Comparison with functioning of other nanoparticulate catalysts on the same reaction proved our product to be an extremely efficient catalyst.

  1. Solid hydrides as hydrogen storage reservoirs; Hidruros solidos como acumuladores de hidrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A.; Sanchez, C.; Friedrichs, O.; Ares, J. R.; Leardini, F.; Bodega, J.; Fernandez, J. F.

    2010-07-01

    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 MgH{sub 2} as a light material are outlined. Researches in course oriented to improve the behaviour of MgH{sub 2} are presented. Finally, other very promising alternative materials such as Al compounds (alanates) or borohydrides as light hydrogen accumulators are also considered. (Author)

  2. Magnetic Cobalt and Cobalt Oxide Nanoparticles in Hyperbranched Polyester Polyol Matrix

    Directory of Open Access Journals (Sweden)

    O. I. Medvedeva

    2017-01-01

    Full Text Available A series of cobalt (Co and its oxides based nanoparticles were synthesized by using hyperbranched polyester polyol Boltorn H20 as a platform and sodium borohydride as a reducing agent. UV, FT-IR, XRD, NTA, and TEM methods were employed to obtain physicochemical characteristics of the products. The average diameter of Co nanoparticles was approximately 8.2±3.4 nm. Their magnetic properties, including hysteresis loop, field-cooled, and zero field-cooled curves were investigated. The nanoparticles exhibit superparamagnetism at room temperature, accompanied by magnetic hysteresis below the blocking temperature.

  3. Optical properties of monodispersed silver nanoparticles produced via reverse micelle microemulsion

    Science.gov (United States)

    Zhang, Danhui; Liu, Xiaoheng; Wang, Xin; Yang, Xujie; Lu, Lude

    2011-04-01

    Silver nanoparticles produced by the sodium borohydride reduction of silver nitrate were stabilized by means of 1-dodecanethiol providing sulfur atom. (n-Dodecyl) trimethylammonium bromide (DTAB), which was used as a phase transfer agent in two-phase system involving water and toluene, played a significant role in the formation of monolayer-protected silver nanoparticles. These nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV-vis), FT-IR spectra and fluorescence. The results indicate that the system is monodispersed and leads to the self-assembly of silver nanoparticles into 0-D quanta-dot arrays.

  4. 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.

  5. Isotope separation

    International Nuclear Information System (INIS)

    Coleman, J.H.; Marks, T.J.

    1981-01-01

    A process for separating uranium isotopes is described which includes: preparing a volatile compound U-T, in which U is a mixture of uranium isotopes and T is a chemical moiety containing at least one organic or deuterated borohydride group, and which exhibits for at least one isotopic species thereof a fundamental, overtone or combination vibrational absorption excitation energy level at a frequency between 900 and 1100 cm -1 ; and irradiating the compound in the vapour phase with energy emitted by a radiation source at a frequency between 900 and 1100 cm -1 (e.g. a CO 2 laser). (author)

  6. Reduction of graphene oxide and its effect on square resistance of reduced graphene oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Zhaoxia; Zhou, Yin; Li, Guang Bin; Wang, Shaohong; Wang, Mei Han; Hu, Xiaodan; Li, Siming [Liaoning Province Key Laboratory of New Functional Materials and Chemical Technology, School ofMechanical Engineering, Shenyang University, Shenyang (China)

    2015-06-15

    Graphite oxide was prepared via the modified Hummers’ method and graphene via chemical reduction. Deoxygenation efficiency of graphene oxide was compared among single reductants including sodium borohydride, hydrohalic acids, hydrazine hydrate, and vitamin C. Two-step reduction of graphene oxide was primarily studied. The reduced graphene oxide was characterized by XRD, TG, SEM, XPS, and Raman spectroscopy. Square resistance was measured as well. Results showed that films with single-step N2H4 reduction have the best transmittance and electrical conductivity with square resistance of ~5746 Ω/sq at 70% transmittance. This provided an experimental basis of using graphene for electronic device applications.

  7. Lignin Sulfonation - A different Approach

    DEFF Research Database (Denmark)

    Bjørkmann, Anders

    2001-01-01

    . It was found that lignin is very reactive, that is why the sulfonation chemistry alone does not necessarily determine its dissolution rate. It became evident that the ultrastructure dispersion of lignin in wood is beneficial for its dissolution. For W, the rate was much higher at pH 1.5 than at 6. MW 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...

  8. Voltammetric and impedimetric properties of nano-scaled -Fe2O3 catalysts supported on multi-walled carbon nanotubes: catalytic detection of dopamine

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-12-01

    Full Text Available purification. 2.1.1. Synthesis of iron and iron oxide nanoparticles Nanoscale zero-valent iron (Fe0) particles were synthesized by the sodium borohydride method as described by Sun et al. [25]. The synthesis was conducted in a flask reactor with three open... as the working electrodes. All solutions were de-aerated by bubbling nitrogen prior to each electrochemical experiment. All experiments were performed at 25?1 ?C. 2.2.1. Preparation of the dopamine hydrochloride injection solution A 2 mL of the drug...

  9. Catalytic Reductions and Tandem Reactions of Nitro Compounds Using in Situ Prepared Nickel Boride Catalyst in Nanocellulose Solution.

    Science.gov (United States)

    Prathap, Kaniraj Jeya; Wu, Qiong; Olsson, Richard T; Dinér, Peter

    2017-09-15

    A mild and efficient method for the in situ reduction of a wide range of nitroarenes and aliphatic nitrocompounds to amines in excellent yields using nickel chloride/sodium borohydride in a solution of TEMPO-oxidized nanocellulose in water (0.01 wt %) is described. The nanocellulose has a stabilizing effect on the catalyst, which increases the turnover number and enables low loading of nickel catalyst (0.1-0.25 mol % NiCl 2 ). In addition, two tandem protocols were developed in which the in situ formed amines were either Boc-protected to carbamates or further reacted with an epoxide to yield β-amino alcohols in excellent yields.

  10. Ultrasonic misting in the treatment of works of art on paper

    Directory of Open Access Journals (Sweden)

    João Paulo Dias

    2005-01-01

    Full Text Available A solution of calcium hydroxide and sodium borohydride was applied using an ultrasonic misting device to a graphite drawing from the artist Guilherme Camarinha. This process allowed the drawing to be washed, reduce its foxing stains and planar distortions without interfering with a fountain pen inscription written by the author in the bottom righthand corner. As there is not much literature regarding this procedure, some practical questions related to the use of ultrasonic dispersions in the treatment of paper are discussed herein.

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

    OpenAIRE

    Meyer, D.E.; Hampson, S.; Ormsbee, L.; Bhattacharyya, D.

    2009-01-01

    Iron nanoaggregates have been prepared using the sodium borohydride reduction method and post-coated with Pd using aqueous phase electro-deposition. The Fe/Pd nanoaggregates were used to examine dechlorination of trichloroethylene (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. A surface-area-normalized first-order rate constant of 1.4 × 10–1 L m–2 h–1 was obtai...

  12. 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)

    Andrzejczuk, A.; Jankowski, K.; Ramsza, A.; Reszke, E.; Strzelec, M.; Tyburska, A.

    2009-01-01

    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)

  13. Synthesis and reactivity of uranium (III) cyclopentadienyl complexes

    International Nuclear Information System (INIS)

    Foyentin, M.

    1987-01-01

    New uranium organometallic complexes are synthetized from the addition compound Cp U (THF). Reactions with lithium compounds, chlorides, alkynes and borohydrides. Oxidizing addition reactions are evidenced with alkyl halogenides. With a strong reducing agent, the complex Cp-UCH-Li allows the fixation and the reduction of nitrogen into ammonia. Lability of ligands bound to U (III) is evidenced, giving very reactive species and hence catalytic properties for these compounds. Catalytic hydrogenation of olefins is studied. Substitution reactions of alkyl groups of these complexes with olefins in presence or not of hydrogen or with alkyllithium are original [fr

  14. Copper-based nanoparticles prepared from copper (II acetate bipyridine complex

    Directory of Open Access Journals (Sweden)

    Lastovina Tatiana A.

    2016-01-01

    Full Text Available We report the synthesis of CuO, Cu/Cu2O and Cu2O/CuO nanoparticles (NPs from the single copper (II acetate bipyridine complex by three different methods:microwave-assisted, solvothermal and borohydride. Presence of bipyridine ligand in the copper complex would impose no need in additional stabilization during synthesis. The phases of formed NPs were identified by X-ray diffraction. CuO NPs of ~11 nm were obtained via solvothermal synthesis from alkaline solution at 160°C. The Cu/Cu2O NPs of ~80 nm were produced via microwave-assisted polyol procedure at 185-200°C, where ethylene glycol can play a triple role as a solvent, a reducing agent and a surfactant. The Cu2O/CuO NPs of ~16 nm were synthesized by a borohydride method at room temperature. Interplanar spacing calculated from the selected-area electron diffraction data confirmed the formation of Cu, CuO and Cu2O phases in respective samples. All NPs are stable and can be used for various applications including biomedicine.

  15. 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. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Immobilization of Candida antarctica Lipase B by Covalent Attachment to Green Coconut Fiber

    Science.gov (United States)

    Brígida, Ana I. S.; Pinheiro, Álvaro D. T.; Ferreira, Andrea L. O.; Pinto, Gustavo A. S.; Gonçalves, Luciana R. B.

    The objective of this study was to covalently immobilize Candida antarctica type B lipase (CALB) onto silanized green coconut fibers. Variables known to control the number of bonds between enzyme and support were evaluated including contact time, pH, and final reduction with sodium borohydride. Optimal conditions for lipase immobilization were found to be 2h incubation at both pH 7.0 and 10.0. Thermal stability studies at 60°C showed that the immobilized lipase prepared at pH 10.0 (CALB-10) was 363-fold more stable than the soluble enzyme and 5.4-fold more stable than the biocatalyst prepared at pH 7.0 (CALB-7). CALB-7 was found to have higher specific activity and better stability when stored at 5°C. When sodium borohydride was used as reducing agent on CALB-10 there were no improvement in storage stability and at 60°C stability was reduced for both CALB-7 and CALB-10.

  17. Green coconut fiber: a novel carrier for the immobilization of commercial laccase by covalent attachment for textile dyes decolourization.

    Science.gov (United States)

    Cristóvão, Raquel O; Silvério, Sara C; Tavares, Ana P M; Brígida, Ana Iraidy S; Loureiro, José M; Boaventura, Rui A R; Macedo, Eugénia A; Coelho, Maria Alice Z

    2012-09-01

    Commercial laccase formulation was immobilized on modified green coconut fiber silanized with 3-glycidoxypropyltrimethoxysilane, aiming to achieve a cheap and effective biocatalyst. Two different strategies were followed: one point (pH 7.0) and multipoint (pH 10.0) covalent attachment. The influence of immobilization time on enzymatic activity and the final reduction with sodium borohydride were evaluated. The highest activities were achieved after 2 h of contact time in all situations. Commercial laccase immobilized at pH 7.0 was found to have higher activity and higher affinity to the substrate. However, the immobilization by multipoint covalent attachment improved the biocatalyst thermal stability at 50 °C, when compared to soluble enzyme and to the immobilized enzyme at pH 7.0. The Schiff's bases reduction by sodium borohydride, in spite of causing a decrease in enzyme activity, showed to contribute to the increase of operational stability through bonds stabilization. Finally, these immobilized enzymes showed high efficiency in the continuous decolourization of reactive textile dyes. In the first cycle, the decolourization is mainly due to dyes adsorption on the support. However, when working in successive cycles, the adsorption capacity of the support decreases (saturation) and the enzymatic action increases, indicating the applicability of this biocatalyst for textile wastewater treatment.

  18. FUNDAMENTAL ENVIRONMENTAL REACTIVITY TESTING AND ANALYSIS OF THE HYDROGEN STORAGE MATERIAL 2LIBH4 MGH2

    Energy Technology Data Exchange (ETDEWEB)

    James, C.; Anton, D.; Cortes-Concepcion, J.; Brinkman, K.; Gray, J.

    2012-01-10

    While the storage of hydrogen for portable and stationary applications is regarded as critical in bringing PEM fuel cells to commercial acceptance, little is known of the environmental exposure risks posed in utilizing condensed phase chemical storage options as in complex hydrides. It is thus important to understand the effect of environmental exposure of metal hydrides in the case of accident scenarios. Simulated tests were performed following the United Nations standards to test for flammability and water reactivity in air for a destabilized lithium borohydride and magnesium hydride system in a 2 to 1 molar ratio respectively. It was determined that the mixture acted similarly to the parent, lithium borohydride, but at slower rate of reaction seen in magnesium hydride. To quantify environmental exposure kinetics, isothermal calorimetry was utilized to measure the enthalpy of reaction as a function of exposure time to dry and humid air, and liquid water. The reaction with liquid water was found to increase the heat flow significantly during exposure compared to exposure in dry or humid air environments. Calorimetric results showed the maximum normalized heat flow the fully charged material was 6 mW/mg under liquid phase hydrolysis; and 14 mW/mg for the fully discharged material also occurring under liquid phase hydrolysis conditions.

  19. Hydrolysis of Mg(BH4)2 and its coordination compounds as a way to obtain hydrogen

    Science.gov (United States)

    Solovev, Mikhail V.; Chashchikhin, Oleg V.; Dorovatovskii, Pavel V.; Khrustalev, Victor N.; Zyubin, A. S.; Zyubina, T. S.; Kravchenko, O. V.; Zaytsev, Alexey A.; Dobrovolsky, Yu. A.

    2018-02-01

    Three ligand-stabilized Mg(BH4)2-based complexes have been synthesized and evaluated as potential hydrogen storage media for portable fuel cell applications. The new borohydrides: Mg(BH4)2 × 0.5Et2O and Mg(BH4)2 × diglyme (diglyme - CH3O(CH2)2O(CH2)2OCH3) have been synthesized and examined by X-ray single crystal diffraction method. Hydrolysis reactions of the compounds liberate hydrogen in quantities ranging from 46 to 96% of the theoretical yield. The hydrolysis of Mg(BH4)2 and other borohydrides is also accompanied by the diborane formation. The amount of liberated diborane depends on the Mg-coordination environment. To explain this fact quantum-chemical calculations have been performed. It is shown that formation of Mg-O-Mg-bridges enables the side process of diborane generation. It means that the size and denticity of the ligand directly affects the amount of released diborane. In general, the larger the ligand and the higher its denticity, the smaller is amount of diborane produced. The new compound Mg(BH4)2 × diglyme decomposes without diborane formation that allows one to be considered as a new promising chemical hydrogen storage compound for the practical usage.

  20. Developing powerful tritide technique: Organic and biological molecule labeling

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Complex hydrides are very important reagents in organic synthesis due to the range of reducing powers and selectivities available from different agents. Unfortunately, the availability of these compounds for radiosynthesis has been extremely limited due to the difficulty of making them with adequate levels of tritium. Investigators at the Lawrence Berkeley Laboratory (LBL) National Tritium Labeling Facility have developed a new addition to the repertoire of the tritium-labeling chemist. The new method allows site-specific incorporation of tritium into organic and biological molecules by efficient reduction processes. Exceptionally reactive and selective reducing agents are prepared and used for labeling in a on-pot process. Three new tritide reagents - supertritide (lithium triethyl borotritide), LiAlT 4 (lithium aluminum tritide), and L-Selectride (sterically hindered lithium tri-sec-butyl borotritide) - have been synthesized at carrier-free levels, and have been demonstrated to be fully reactive. The availability of these versatile and reactive reagents gives the tritium radiochemist great control over chemoselectivity and stereoselectivity. The LBL tritide reagents can drive numerous conventional chemical reactions, and have been used to reduce p-toluene sulfonates, amides, lactones, esters, and aldehydes. These reactions produce good yields and result in products with maximum specific activities. The reagents clearly exhibit superior reactivity and may be used in many more synthetic processes than sodium borohydride, which is the currently used reagent. In addition, tritide reagents such as L-selectride have been shown to give greater control over stereochemistry and selectivity than sodium borohydride

  1. Synthesis and Complex Formation with 99mTc of Ligands Diamidedithiol and N-acylthiourea Metronidazole Derivatives for Visualization of Hypoxia Processes

    International Nuclear Information System (INIS)

    Ramos Cairo, Raúl; Llanes Guilarte, Lianet; Mocelo Castell, Raúl; Plutín Stevens, Ana María; Calderón Sánchez, Osmar; Zayas Crespo, Francisco; Mesa Dueñas, Niurka; Leyva Montaña, René

    2016-01-01

    Hypoxia is described as the presence of low oxygen concentrations in the cell. In the case of the existence of tumors, the manifestation of this process confers inefficiency to the radiotherapies. In the literature, the use of nitroimidazole derivatives as good hypoxic markers has been reported. In the present work the synthesis of five bifunctional chelating agents derived from metronidazole (2-methyl-5-nitro-imidazole) was developed as final products of systematic multi-step synthesis strategies. The preparation of these compounds has not been reported in the literature consulted. The chelation system which has one of the ligands is N2S2 diamidedithiol (with 3,4-diaminobenzoic acid as the central support for the formation of the chelating molecule), while the other four are in the N-alkyl-N '-acylthioureas. The compounds obtained were spectroscopically characterized (IR, 1H-NMR and 13C-NMR) and their physical properties. A procedure was developed that led to the formation of five new complexes with 99m Tc ( 99m Tc) from the synthesized ligands. For this purpose, two reducing agents were used: tin fluoride (II) and sodium borohydride. Radiochemical yields ranged from 48 to 76%, and the best results were achieved using sodium borohydride. (author)

  2. 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

    2012-07-19

    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.

  3. High yield synthesis of Au25 nanoclusters by controlling the reduction process.

    Science.gov (United States)

    Jin, Shenshen; Meng, Xiangming; Jin, Shan; Zhu, Manzhou

    2013-02-01

    The syntheses of gold nanoclusters, namely, the 25-gold-atom nanocluster (Au25(SR)18) and 38-gold-atom nanocluster (Au38(SR)24), with SR representing the thiol ligand, were described in previously reported studies. The synthesis was via a fast reduction process using sodium borohydride. The ratio of Au:HSR:NaBH4 was 1:3:10. Herein we report that the Au25 nanocluster can also be synthesized via a slow reduction process through a dropwise addition of an aqueous solution of sodium borohydride. The ratio of Au:S:NaBH4 is also changed to 1:3:5. This method synthesized Au25 nanoclusters at a high yield (47%). Pure Au25 nanoclusters were obtained after extraction, and the product was fully characterized by UV-vis spectroscopy, thermogravimetric analysis (TGA) and Matrix-Assisted Laser Desorption/Ionization (MALDI) mass spectrometry. The possible formation mechanism is discussed in this paper. This work contributes to a better understanding of the mechanism of Au25 formation and provides a basis for further study of gold nanoclusters.

  4. Novel materials for fuel cells operating on liquid fuels

    Directory of Open Access Journals (Sweden)

    César A. C. Sequeira

    2017-05-01

    Full Text Available Towards commercialization of fuel cell products in the coming years, the fuel cell systems are being redefined by means of lowering costs of basic elements, such as electrolytes and membranes, electrode and catalyst materials, as well as of increasing power density and long-term stability. Among different kinds of fuel cells, low-temperature polymer electrolyte membrane fuel cells (PEMFCs are of major importance, but their problems related to hydrogen storage and distribution are forcing the development of liquid fuels such as methanol, ethanol, sodium borohydride and ammonia. In respect to hydrogen, methanol is cheaper, easier to handle, transport and store, and has a high theoretical energy density. The second most studied liquid fuel is ethanol, but it is necessary to note that the highest theoretically energy conversion efficiency should be reached in a cell operating on sodium borohydride alkaline solution. It is clear that proper solutions need to be developed, by using novel catalysts, namely nanostructured single phase and composite materials, oxidant enrichment technologies and catalytic activity increasing. In this paper these main directions will be considered.

  5. Influence of synthesis parameters on iron nanoparticle size and zeta potential

    Science.gov (United States)

    Goldstein, Nikki; Greenlee, Lauren F.

    2012-03-01

    Zero valent iron nanoparticles are of increasing interest in clean water treatment applications due to their reactivity toward organic contaminants and their potential to degrade a variety of compounds. This study focuses on the effect of organophosphate stabilizers on nanoparticle characteristics, including particle size distribution and zeta potential, when the stabilizer is present during nanoparticle synthesis. Particle size distributions from DLS were obtained as a function of stabilizer type and iron precursor (FeSO4·7H2O or FeCl3), and nanoparticles from 2 to 200 nm were produced. Three different organophosphate stabilizer compounds were compared in their ability to control nanoparticle size, and the size distributions obtained for particle volume demonstrated differences caused by the three stabilizers. A range of stabilizer-to-iron (0.05-0.9) and borohydride-to-iron (0.5-8) molar ratios were tested to determine the effect of concentration on nanoparticle size distribution and zeta potential. The combination of ferrous sulfate and ATMP or DTPMP phosphonate stabilizer produced stabilized nanoparticle suspensions, and the stabilizers tested resulted in varying particle size distributions. In general, higher stabilizer concentrations resulted in smaller nanoparticles, and excess borohydride did not decrease nanoparticle size. Zeta potential measurements were largely consistent with particle size distribution data and indicated the stability of the suspensions. Probe sonication, as a nanoparticle resuspension method, was minimally successful in several different organic solvents.

  6. Influence of synthesis parameters on iron nanoparticle size and zeta potential

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, Nikki; Greenlee, Lauren F., E-mail: lauren.greenlee@nist.gov [National Institute of Standards and Technology, Materials Reliability Division (United States)

    2012-03-15

    Zero valent iron nanoparticles are of increasing interest in clean water treatment applications due to their reactivity toward organic contaminants and their potential to degrade a variety of compounds. This study focuses on the effect of organophosphate stabilizers on nanoparticle characteristics, including particle size distribution and zeta potential, when the stabilizer is present during nanoparticle synthesis. Particle size distributions from DLS were obtained as a function of stabilizer type and iron precursor (FeSO{sub 4}{center_dot}7H{sub 2}O or FeCl{sub 3}), and nanoparticles from 2 to 200 nm were produced. Three different organophosphate stabilizer compounds were compared in their ability to control nanoparticle size, and the size distributions obtained for particle volume demonstrated differences caused by the three stabilizers. A range of stabilizer-to-iron (0.05-0.9) and borohydride-to-iron (0.5-8) molar ratios were tested to determine the effect of concentration on nanoparticle size distribution and zeta potential. The combination of ferrous sulfate and ATMP or DTPMP phosphonate stabilizer produced stabilized nanoparticle suspensions, and the stabilizers tested resulted in varying particle size distributions. In general, higher stabilizer concentrations resulted in smaller nanoparticles, and excess borohydride did not decrease nanoparticle size. Zeta potential measurements were largely consistent with particle size distribution data and indicated the stability of the suspensions. Probe sonication, as a nanoparticle resuspension method, was minimally successful in several different organic solvents.

  7. Influence of synthesis parameters on iron nanoparticle size and zeta potential

    International Nuclear Information System (INIS)

    Goldstein, Nikki; Greenlee, Lauren F.

    2012-01-01

    Zero valent iron nanoparticles are of increasing interest in clean water treatment applications due to their reactivity toward organic contaminants and their potential to degrade a variety of compounds. This study focuses on the effect of organophosphate stabilizers on nanoparticle characteristics, including particle size distribution and zeta potential, when the stabilizer is present during nanoparticle synthesis. Particle size distributions from DLS were obtained as a function of stabilizer type and iron precursor (FeSO 4 ·7H 2 O or FeCl 3 ), and nanoparticles from 2 to 200 nm were produced. Three different organophosphate stabilizer compounds were compared in their ability to control nanoparticle size, and the size distributions obtained for particle volume demonstrated differences caused by the three stabilizers. A range of stabilizer-to-iron (0.05–0.9) and borohydride-to-iron (0.5–8) molar ratios were tested to determine the effect of concentration on nanoparticle size distribution and zeta potential. The combination of ferrous sulfate and ATMP or DTPMP phosphonate stabilizer produced stabilized nanoparticle suspensions, and the stabilizers tested resulted in varying particle size distributions. In general, higher stabilizer concentrations resulted in smaller nanoparticles, and excess borohydride did not decrease nanoparticle size. Zeta potential measurements were largely consistent with particle size distribution data and indicated the stability of the suspensions. Probe sonication, as a nanoparticle resuspension method, was minimally successful in several different organic solvents.

  8. Identification of enzyme-bound activated CO2 as carbonic-phosphoric anhydride: isolation of the corresponding trimethyl derivative from the active site of glutamine-dependent carbamyl phosphate synthetase.

    Science.gov (United States)

    Powers, S G; Meister, A

    1976-09-01

    The activated CO2 intermediate formed in the reaction catalyzed by glutamine-dependent carbamyl phosphate synthetase was identified as carbonic-phosphoric anhydride through the use of two independent procedures. The carboxy phosphate intermediate was reduced to formate by treatment with potassium borohydride. Although both free CO2 and the enzyme-bound activated CO2 are reduced to formic acid by borohydride, it was possible to selectively introduce a 14C label into the enzyme-bound activated CO2 and thus into the formic acid derived from it. Such [14C]formate formation required the presence of ATP, KCl, and the enzyme, and evidence was obtained that the [14C]formate found is not derived from carbamyl phosphate or from bicarbonate bound nonspecifically to the enzyme. When the enzyme was treated with L-2-amino-4-oxo-5-chloropentanoate (or cyanate), the formation of [14C]formate was increased about 2-fold, a finding consistent with the previous observation that such treatment effects a similar increase in the bicarbonate-dependent cleavage of ATP catalyzed by the enzyme. When reaction mixtures containing the enzyme, [gamma-32P]ATP, and [14C]bicarbonate were methylated by treatment with diazomethane, a labeled compound was formed which cochromatographed with authentic trimethyl carboxy phosphate. Equimolar quantities of 14C and 32P wer incorporated into the intermediate, thus confirming its identification as carboxy phosphate. Nonenzymatic transphosphorylation from ATP to bicarbonate to form carboxy phosphate was also detected by diazomethane trapping.

  9. In situ development of nanosilver-impregnated bacterial cellulose for sustainable released antimicrobial wound dressing.

    Science.gov (United States)

    Mohite, Bhavana V; Patil, Satish V

    2016-04-06

    Bacterial cellulose (BC) is an interesting biomaterial found application in various fields due to its novel characteristics like purity, water holding capacity, degree of polymerization and mechanical strength. BC as wound dressing material has limitation because it has no antimicrobial activity. To circumvent this problem, the present study was carried out by impregnation of silver on bacterial cellulose surface. Bacterial cellulose was produced by Gluconoacetobacter hansenii (strain NCIM 2529) by shaking culture method. The sodium borohydride and classical Tollens reaction was used for silver nanoparticle synthesis. The effectiveness of sodium borohydride method compared with Tollens reaction was evaluated on the basis of silver nanoparticle formation and its impregnation on BC as evidenced by UV-Vis spectrum analysis, FE-SEM-EDS analysis and FT-IR spectrum. The potential of nano silver impregnated BC was determined for sustained release antimicrobial wound dressing material by swelling ratio, mechanical properties and antimicrobial activity against Staphylococcus aureus. Thus the nanosilver impregnated bacterial cellulose as promising antimicrobial wound dressing material was evidenced.

  10. Kinetic analysis and chemical modification studies of nicotinate phosphoribosyltransferase from yeast

    International Nuclear Information System (INIS)

    Hess, S.L.

    1988-01-01

    Nicotinate phosphoribosyltransferase (NaPRTase) from Baker's yeast catalyzes the formation of nicotinate mononucleotide (NaMN) and pyrophosphate from phosphoribosyl α-1-pyrophosphate and nicotinate, concomitant with ATP hydrolysis. Using purified NaPRTase, initial velocity measurements were performed varying one substrate concentration at different fixed levels of the second substrate and maintaining the third substrate constant. Subsequently, an exchange of label was observed between ATP and [ 14 C]-ADP. This rate of exchange was inhibited by PRibPP and pyrophosphate. Incubations of NaPRTase with pyridoxal 5'-phosphate followed by sodium borohydride reduction led to inactivation of the enzyme. Pyridoxal was a less effective inhibitor than pyridoxal 5'-phosphate. The inactivation of the enzyme by pyridoxal 5'-phosphate was reversible upon flow dialysis, whereas reduction of the enzyme-pyridoxal complex with sodium borohydride rendered the inhibition irreversible. The presence of ATP or PRibPP, with or with Mg 2+ , provided protection against this inactivation, while a kinetic analysis revealed the inhibition to be competitive, and noncompetitive, respectively. One mole of [ 3 H]-pyridoxal phosphate was required to completely inactivate the enzyme, which was reduced in the presence of MgATP and MgPRibPP to 0.2 and 0.6, respectively. No incorporation of pyridoxal 5'-phosphate was observed in the combination of both of the two substrates

  11. Innovative hydrogen storage in hollow glass-microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Keding, M.; Schmid, G.; Tajmar, M. [Austrian Research Centers, Vienna (Austria)

    2009-07-01

    Hydrogen storage technologies are becoming increasingly important for a number of future applications. The Austrian Research Centers (ARC) are developing a unique hydrogen storage system that combines the advantages of both hollow glass microsphere and chemical compound hydrogen storage, but eliminates their respective drawbacks. Water is utilized as a functional liquid to carry the hollow glass microspheres that are loaded with up to 700 bar of hydrogen gas. Sodium borohydride (NaBH{sub 4}) is then injected together with the glass microspheres into a reaction chamber where the water reacts catalytically with the NaBH{sub 4} producing hydrogen and heat. The heat is then utilized to release the hydrogen from the hollow glass microspheres providing a double hydrogen generation process without any external energy or heat during storage or gas release. The paper described this hydrogen storage system with particular reference to microspheres, the coating process, the experimental facility and NaBH{sub 4} test results. It was concluded that hydrogen storage and production on demand is possible with microspheres and sodium borohydride solution. 9 refs., 16 figs.

  12. Degradation of Polybrominated Aiphenyl Ethers in a UV Advanced Reduction Process with Different Reducing Agents

    Science.gov (United States)

    Dong, Xiaoqing; Li, Chaolin; Zheng, Wei; Wang, Guosheng

    2018-02-01

    Polybrominated diphenyl ethers (PBDEs) are toxic and persistent, and their efficient degradation is currently a challenge. In this study, decabromodiphenyl ether (BDE-209) was selected as the target compound and was degraded by a UV photochemical system with different reducing agent. The result showed that the optimal BDE-209 removal in 1 hour by UV/sodium sulphite (Na2SO3) was 86.87%. With the same concentration of BDE-209 and reaction time, the optimal removal rate by UV/sodium borohydride (NaBH4) was 89.25%. Kinetic analysis revealed that the degradation of BDE-209 conformed to the first-order kinetic model. The order of rate constant of different UV photochemical processes is kUVborohydride showed a better enhanced effect for the removal of bromines.

  13. Synthesis, characterization and spectroscopic studies of some boron-containing hydrogen storage materials

    Science.gov (United States)

    Jash, Panchatapa

    In this dissertation the synthesis and characterization of boron-related nanostructures and dehydrogenation studies of metal borohydrides using FTIR are reported. Boron-related nanostructures are of interest because of their potential applications in nanoelectronics and in hydrogen storage. A low pressure chemical vapor deposition (LPCVD) apparatus was built in order to grow boron nanostructures. Various techniques, namely, Auger electron spectroscopy (AES), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used to characterize the synthesized boron and boride nanostructures, and boron coated carbon nanotubes (CNTs). By the uncatalyzed pyrolysis of diborane, at relatively low temperature, crystalline boron nanoribbons were synthesized. Nickel-catalyzed growth also produced Ca, Sr and Y boride nanowires that were found to be crystalline. Amorphous boron coated CNTs were synthesized by LPCVD. Two growth mechanisms, vapor-liquid-solid (VLS) and vapor-solid (VS) were invoked to explain the observed nanostructures. A high vacuum apparatus for FTIR studies was built. The capabilities of the apparatus were first tested by acquiring low temperature and room temperature spectra of sodium and lithium borohydrides. The metal borohydrides are of high hydrogen content and dehydrogenation studies using FTIR were done. NaBH 4 and the K2B12H12 salt were studied. It was found that above its melting point (673 K), NaBH4 is probably converted to its B12H12-2 salt, which then loses all hydrogen to produce amorphous boron. This conversion of B 12H12-2 to boron clusters was confirmed through dehydrogenation studies of K2B12H12. Both SIMS and AES are surface sensitive techniques to study thin film surfaces and interfaces at nano-dimentions. Thin (9-10 mum) cadmium telluride films have application as the buffer layer on silicon substrates to form high

  14. Preparation of silver nanoparticles at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Mini, E-mail: mishramini5@gmail.com [Centre of Environmental Science, Department of Botany, University of Allahabad, Allahabad, U.P. (India); Chauhan, Pratima, E-mail: mangu167@yahoo.co.in [Department of Physics, University of Allahabad, Allahabad U.P. (India)

    2016-04-13

    Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

  15. 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

    2015-10-01

    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.

  16. Magnetic structures synthesized by controlled oxidative etching: Structural characterization and magnetic behavior

    Directory of Open Access Journals (Sweden)

    Álvaro de Jesús Ruíz-Baltazar

    Full Text Available A facile strategy for the fabrication Fe3O4 nanostructures at room temperature and with well-defined morphology is proposed. In this methodology, the iron precursors were reduced by sodium borohydride. Subsequently an oxidative etching process promotes the formation of Fe2O3 nanostructures. Magnetic measurements revealed a well-defined superparamagnetic behavior for the material. The Zero-Field-Cooled (ZFC and Field-Cooled (FC magnetization curves reveals that critical and blocking temperature were 24 and 350 °C respectively. The Fe3O4 nanostructures were characterized using aberration-corrected (Cs scanning transmission electron microscopy (STEM and energy dispersive spectroscopy (EDS. Additionally, Raman spectra support the Fe3O4 presence and corroborate the efficiency of the synthesis process to obtain magnetite. Keywords: Chemical synthesis, Fe3O4 nanoparticles, Structural characterization, Magnetic properties

  17. Antimicrobial activity of silver nanoparticles impregnated wound dressing

    Science.gov (United States)

    Shinde, V. V.; Jadhav, P. R.; Patil, P. S.

    2013-06-01

    In this work, silver nanoparticles were synthesized by simple wet chemical reduction method. The silver nitrate was reduced by Sodium borohydride used as reducing agent and Poly (vinyl pyrrolidone) (PVP) as stabilizing agent. The formation of silver nanoparticles was evaluated by UV-visible spectroscope and transmission electron microscope (TEM). Absorption spectrum consist two plasmon peaks at 410 and 668 nm revels the formation of anisotropic nanoparticles confirmed by TEM. The formation of silver nanoparticles was also evidenced by dynamic light scattering (DLS) study. DLS showed polydisperse silver nanoparticles with hydrodynamic size 32 nm. Protecting mechanism of PVP was manifested by FT-Raman study. Silver nanoparticles were impregnated into wound dressing by sonochemical method. The Kirby-Bauer disc diffusion methods were used for antimicrobial susceptibility testing. The antimicrobial activity of the samples has been tested against gram-negative bacterium Escherichia coli and gram-positive bacterium Staphylococcus aureus.

  18. 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.

  19. MOF-Derived Cu@Cu2O Nanocatalyst for Oxygen Reduction Reaction and Cycloaddition Reaction

    Directory of Open Access Journals (Sweden)

    Aram Kim

    2018-02-01

    Full Text Available Research on the synthesis of nanomaterials using metal-organic frameworks (MOFs, which are characterized by multi-functionality and porosity, as precursors have been accomplished through various synthetic approaches. In this study, copper and copper oxide nanoparticles were fabricated within 30 min by a simple and rapid method involving the reduction of a copper(II-containing MOF with sodium borohydride solution at room temperature. The obtained nanoparticles consist of a copper core and a copper oxide shell exhibited catalytic activity in the oxygen reduction reaction. The as-synthesized Cu@Cu2O core-shell nanocatalyst exhibited an enhanced limit current density as well as onset potential in the electrocatalytic oxygen reduction reaction (ORR. Moreover, the nanoparticles exhibited good catalytic activity in the Huisgen cycloaddition of various substituted azides and alkynes under mild reaction conditions.

  20. Gamma ray induced chromophore modification of softwood thermomechanical pulp

    International Nuclear Information System (INIS)

    Robert, S.; Daneault, C.; Viel, C.; Lepine, F.

    1992-01-01

    This study focuses on bleaching a softwood (black spruce, balsam fur) thermomechanical pulp with gamma rays. Gamma rays are known for their enormous penetrating power, along with their ionizing properties. They can generate highly energetic radicals capable of oxidizing lignin chromophores. The authors studied the influence of isopropyl alcohol, sodium borohydride, oxygen, hydrogen peroxide, nitrogen dioxide and water along with gamma ray irradiation of the pulps. The authors measured the optimal dose and dose rate, along with the influence of the radical scavengers like oxygen on the bleaching effect of gamma irradiated pulps. They observe various degrees of bleaching of these pulps. Evidence relates this bleaching to the generation of perhydroxyl anions upon irradiation of water. Also, they were able to pinpoint the influence of the dose rate on the rate of formation and disappearance of these perhydroxyl anions and their influence on bleaching kinetics. Stability toward photoyellowing, and photoyellowing's kinetic of papers from these pulps was also studied

  1. 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.

  2. 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.

  3. Cellulose nanocrystal-derived hollow mesoporous carbon spheres and their application as a metal-free catalyst

    Science.gov (United States)

    Hadidi, Lida; Mahmoud, Ahmed Y. F.; Purkait, Tapas K.; McDermott, Mark T.; Veinot, Jonathan G. C.

    2017-12-01

    In this contribution, we demonstrate the fabrication of hollow mesoporous carbon spheres (HCSs) derived from cellulose nanocrystals (CNCs). The HCSs were prepared by templating CNCs onto sacrificial silica spheres followed by heat treatment. Mesoporous carbon spheres result from the removal of the silica spheres by etching. The walls of the HCSs are approximately 4 nm thick and are composed of amorphous and graphitic carbon. The catalytic activity of the HCSs was investigated for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH4). The present investigation reveals the outstanding catalytic activity of these particles. The reaction rate followed pseudo-first order kinetics with k value of 4.72 × 10‑3 s‑1 and activity parameter of 52.2 s‑1 g‑1, which showed superior performance compared to that of metal nanoparticle and metal nanoparticle-carbon hybrid based catalysts.

  4. 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.

  5. Controlled Synthesis and Magnetic Properties of Uniform Hierarchical Polyhedral α-Fe2O3 Particles

    Science.gov (United States)

    Long, Nguyen Viet; Yang, Yong; Thi, Cao Minh; Phuc, Le Hong; Nogami, Masayuki

    2017-06-01

    The controlled synthesis of uniform hierarchical polyhedral iron (Fe) micro-/nanoscale oxide particles with the α-Fe2O3 structure is presented. The hierarchical polyhedral iron oxide particles were synthesized by modified polyol methods with sodium borohydride as a powerful and efficient reducing agent. A critical heat treatment process used during the synthesis allowed for the interesting formation of α-Fe2O3 hematite with a micro-/nanoscale structure. The structure and weak ferromagnetism of the α-Fe2O3 particles were investigated by x-ray diffraction with whole pattern fitting and Rietveld refinement, scanning electron microscopy, and by vibrating sample magnetometry. The as-prepared α-Fe2O3 particles and the three dimensional models presented have promising practical applications for energy storage and conversion in batteries, capacitors, and fuel cells, and related spintronic devices and technologies.

  6. Preparation of riboflavin specifically labeled in the 5'-hydroxymethyl terminus using a vitamin B2-aldehyde-forming enzyme from Schizophyllum commune

    International Nuclear Information System (INIS)

    Kekelidze, T.N.; Edmondson, D.E.; McCormick, D.B.

    1995-01-01

    A method is described for synthesis of riboflavin selectively labeled in the hydrogens at the 5'-hydroxymethyl position. In this method, a vitamin B 2 -aldehyde-forming enzyme from Schizophyllum commune is used to specifically and completely oxidize the 5'-hydroxymethyl of riboflavin to the 5'-aldehyde. This reaction is monitored spectrophotometrically by the reduction of 2,6-dichlorophenolindophenol at 600 nm. Appearance of aldehyde product was directly quantitated by reverse-phase high-performance liquid chromatography. Product is extracted from the incubation mixture by phenol after saturation with (NH 4 ) 2 SO 4 and then further purified by benzyl alcohol extraction. The 5'-aldehyde is reduced with appropriately labeled sodium borohydride to yield the vitamin specifically labeled in the 5'-hydroxymethyl group. (author)

  7. Study of film graphene/graphene oxide obtained by partial reduction chemical of oxide graphite; Estudo de filme de grafeno/oxido de grafeno obtido por reducao quimica parcial do oxido de grafite

    Energy Technology Data Exchange (ETDEWEB)

    Gascho, J.L.S.; Costa, S.F.; Hoepfner, J.C.; Pezzin, S.H., E-mail: juliagascho@hotmail.com [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2014-07-01

    This study investigated the morphology of graphene/graphene oxide film obtained by partial chemical reduction of graphite oxide (OG) as well as its resistance to solvents. Films of graphene/graphene oxide are great candidates for replacement of indium oxide doped with tin (ITO) in photoelectric devices. The OG was obtained from natural graphite, by Hummer's method modified, and its reduction is made by using sodium borohydride. Infrared spectroscopy analysis of Fourier transform (FTIR), Xray diffraction (XRD) and scanning electron microscopy, high-resolution (SEM/FEG) for the characterization of graphene/graphene oxide film obtained were performed. This film proved to be resilient, not dispersing in any of the various tested solvents (such as ethanol, acetone and THF), even under tip sonication, this resistance being an important property for the applications. Furthermore, the film had a morphology similar to that obtained by other preparation methods.(author)

  8. Silver nanoparticles prepared by chemical reduction-protection method, and their application in electrically conductive silver nanopaste

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jianguo, E-mail: ljg712@yahoo.com.c [Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Li Xiangyou; Zeng Xiaoyan [Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2010-04-02

    Ag nanoparticles were prepared in a water-phase system with a mixture of silver-ammonia complex, sodium borohydride, and lauric acid according to molar feed ratio of approximately 6:3:1. The mechanism of preparation and separation by chemical reduction-protection method was explored. The as-synthesized Ag nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis spectroscopy, respectively. It was found that the size of high purity Ag particles was ranging from 30 to 50 nm with slight agglomeration. In addition, the as-synthesized wet Ag nanoparticles were dispersed stably in organic vehicle to formulate electrically conductive nanopaste. Upon direct-written and sintered, the array pattern of the nanopaste with the resolution of about 30 {mu}m was achieved with the electrical resistivity in the order of magnitude of 10{sup -5} {Omega} cm.

  9. Study on gelatin-silver nanoparticle composite towards the development of bio-based antimicrobial film.

    Science.gov (United States)

    Halder, Dipankar; Mitra, Atanu; Bag, Surajit; Raychaudhuri, Utpal; Chakraborty, Runu

    2011-12-01

    Nano-scale silver particle stabilized by gelatin protein was prepared through the reduction of aqueous silver nitrate solution by sodium borohydride. Gelatin concentration was varied against a fixed concentration of silver nitrate to optimize the gelatin to metal ratio. Gelatin-protected Ag-nanoparticle was characterized by UV-VIS spectroscopy and transmission electron microscopy (TEM). All the samples exhibited similar yellow color with a characteristic plasmonic band of silver nanoparticles at 412 nm. TEM micrographs also showed the presence of nanoscale silver particles of approximately 3.9 nm. Since silver has strong bactericidal properties and at the same time relatively less toxic to human cell, silver in various forms is ideally suited for a wide range of applications in consumer, industrial and medical products The antimicrobial properties of gelatin-silver nanocomposites were tested by 'cup-plate zone of inhibition' method. The nanocomposites exhibited significant antibacterial and antifungal activity.

  10. Preparation of raspberry-like polypyrrole composites with applications in catalysis.

    Science.gov (United States)

    Yao, Tongjie; Wang, Chuanxi; Wu, Jie; Lin, Quan; Lv, Hui; Zhang, Kai; Yu, Kui; Yang, Bai

    2009-10-15

    Raspberry-like composites were prepared by coating the silver/polypyrrole core/shell composites onto the surface of silica spheres via oxidation polymerization of pyrrole monomer with [Ag(NH3)2]+ ions as oxidants. The whole process allowed the absence of stabilizers, which greatly improved the quality of the conducting polymer composites. The morphology of the resulting composites was investigated, which can be described as raspberry-like; also, the structure and composition of the composites were characterized in detail. A possible formation mechanism was proposed. The present synthetic strategy substantially extended the scope of metal/conducting polymer composite synthesis. The raspberry-like composites exhibited excellent catalytic properties in the reduction of methylene blue dye with the reducing agent of sodium borohydride.

  11. Synthesis of camptothecin-loaded gold nanomaterials

    International Nuclear Information System (INIS)

    Xing Zhimin; Liu Zhiguo; Zu Yuangang; Fu Yujie; Zhao Chunjian; Zhao Xiuhua; Meng Ronghua; Tan Shengnan

    2010-01-01

    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.

  12. Structure determination of the neutral exopolysaccharide produced by Lactobacillus delbrueckii subsp. bulgaricus OLL1073R-1.

    Science.gov (United States)

    Van Calsteren, Marie-Rose; Gagnon, Fleur; Nishimura, Junko; Makino, Seiya

    2015-09-02

    The neutral exopolysaccharide (NPS) of Lactobacillus delbrueckii subsp. bulgaricus strain OLL1073R-1 was purified and characterized. The molecular mass was 5.0×10(6) g/mol. Sugar and absolute configuration analyses gave the following composition: d-Glc, 1; d-Gal, 1.5. The NPS was also submitted to periodate oxidation followed by borohydride reduction and Smith degradation. Sugar and methylation analyses, (1)H and (13)C nuclear magnetic resonance, and mass spectrometry of the NPS or of its specifically modified products allowed determining the repeating unit sequence: {2)Glc(α1-3)Glc(β1-3)[Gal(β1-4)]Gal(β1-4)Gal(α1-}n. The structure is compared to that of exopolysaccharides produced by other Lactobacillus bulgaricus strains. Copyright © 2015. Published by Elsevier Ltd.

  13. Organosulphur Compounds in Coals as Determined by Reaction with Raney Nickel and Microscale Pyrolysis Techniques. Quarterly report, January-March, 1996

    International Nuclear Information System (INIS)

    Stalker, L.; Philip, P.

    1997-01-01

    Since the last report, we have concentrated on completing all the chemical degradation experimental work. This has involved the completion of a series of chemical degradation experiments using deuterium labeled sodium borohydride and deuterated methanol . The products of these desulphurization experiments have, as usual, been fractionated into aliphatic and aromatic hydrocarbons and NSO compounds. The aliphatic hydrocarbon fractions of each desulphurization experiment are currently being analysed by gas chromatography(GC) and gas chromatography-mass spectrometry(GCMS). The object of the deuterium labelling experiments is to determine the relative abundance of thioether, triolane, and thiophene organic sulphur units cleaved in the different coal fractions( i.e. pre- extracted coal matrix, asphaltene and free polars from the maltenes)

  14. A fast method for the determination of lead in honey samples using stabilizer-free silver nanoparticles

    Science.gov (United States)

    Bittar, Dayana Borges; Catelani, Tiago Augusto; Pezza, Leonardo; Pezza, Helena Redigolo

    2018-01-01

    A sensitive, rapid and robust method based on the use of stabilizer-free silver nanoparticles was developed for lead detection in honey. Silver nanoparticles were synthesized without the presence of any stabilizers using silver nitrate and sodium borohydride as precursors where the latter was applied as reducing agent. The optimization of the experimental variables (AgNO3 and NaBH4) for the formation of the nanoparticles was carried out using varying volumes of these solutions. Spectrophotometric measurements at 393 nm showed a linear working range between 0.0500 and 0.167 mg L- 1 lead (R = 0.994), with limits of detection (LOD) and quantification (LOQ) of 0.0135 and 0.0451 mg L- 1, respectively. The proposed method proved to be a significantly sensitive mechanism for lead detection in honey samples.

  15. Synthesis of palladium nanoparticles with leaf extract of Chrysophyllum cainito (Star apple) and their applications as efficient catalyst for C-C coupling and reduction reactions

    Science.gov (United States)

    Majumdar, Rakhi; Tantayanon, Supawan; Bag, Braja Gopal

    2017-10-01

    A simple green chemical method for the one-step synthesis of palladium nanoparticles (PdNPs) has been described by reducing palladium (II) chloride with the leaf extract of Chrysophyllum cainito in aqueous medium. The synthesis of the palladium nanoparticles completed within 2-3 h at room temperature, whereas on heat treatment (70-80 °C), the synthesis of colloidal PdNPs completed almost instantly. The stabilized PdNPs have been characterized in detail by spectroscopic, electron microscopic and light scattering measurements. The synthesized PdNPs have been utilized as a green catalyst for C-C coupling reactions under aerobic and phosphine-free conditions in aqueous medium. In addition, the synthesized PdNPs have also been utilized as a catalyst for a very efficient sodium borohydride reduction of 3- and 4-nitrophenols. The synthesized PdNPs can retain their catalytic activity for several months.

  16. Investigation on 3H-labelled bilirubin for study of blood-brain barrier

    International Nuclear Information System (INIS)

    Cao Rongzhen; Dong Mo; Zhang Yulong; Zhou Ruiju

    1996-01-01

    Synthesis of 3 H-labelled bilirubin is described. 3 H-bilirubin is prepared by the reduction of biliverdin using sodium boro-[ 3 H]-hydride in methanol solvent. But biliverdin is synthesized through dehydrogenation of bilirubin with 2,3- dichloro-5, 6-dicyanobenzoquinone (DDQ) in dimethyl sulphoxide and sodium boro-[ 3 H]-hydride is produced by exchange of sodium boro-hydride with tritium gas using nickel catalyst at high temperature. The specific activity of obtained 3 H-bilirubin is 306 GBq/mmol, while the radiochemical purity is over 95% by HPLC and paper chromatography. The permeated profile of 3 H-labelled bilirubin in rat brain has been obtained in animal experiments

  17. Nonempirical investigations of the structure and stability of complex boro- and alumohydrides of K, Ca, Cu and Zn

    International Nuclear Information System (INIS)

    Musaev, D.G.; Charkin, O.P.

    1991-01-01

    Using nonempirical MO LCAO SCF method the structural and relative energy characteristics of boro- and alumohydrides of alternative configurations, CuAlH 4 , ZnBH 4 + , ZnAlH 4 + and HZnAlH 4 , were calculated. Differences and similarities in the properties of identical boro- and alumohydrides, as well as L 1 MH 4 , HL 2 MH 4 and L 2 MH 4 + molecules with the change of cation in the series K + -HCa + -Ca 2+ and Cu + -HZn + -Zn 2+ on the one hand, and with Cu and Zn substitution for K and Ca on the other hand, were considered. It was shown that alumohydrides of electropositive alkali and alkaline-earth cations K and Ca are less, and those of transition metals Cu and Zn are more hard to cation migration around AlH 4 - and BH 4 - anions than borohydrides

  18. The Mode of Action of Silver and Silver Halides Nanoparticles against Saccharomyces cerevisiae Cells

    Directory of Open Access Journals (Sweden)

    A. A. Kudrinskiy

    2014-01-01

    Full Text Available Silver and silver halides nanoparticles (NPs (Ag, AgCl, AgBr, and AgI capped with two different stabilizers (sodium citrate and nonionic surfactant Tween 80 were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The effect of the biocidal action of as-prepared synthesized materials against yeast cells Saccharomyces cerevisiae was compared to the effect produced by silver nitrate and studied through the measurement of cell loss and kinetics of K+ efflux from the cells depending on concentration of silver. The results clearly indicate that the silver ions either remained in the dispersion of silver NPs and silver halides NPs after their synthesis or were generated afterwards by dissolving silver and silver halides particles playing a major part in the cytotoxic activity of NPs against yeast cells. It was also supposed that this activity most likely does not relate to the damage of cell membrane.

  19. 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...

  20. Aqueous-Phase Catalytic Chemical Reduction of p-Nitrophenol Employing Soluble Gold Nanoparticles with Different Shapes

    Directory of Open Access Journals (Sweden)

    Francyelle Moura de Oliveira

    2016-12-01

    Full Text Available Gold nanoparticles with different shapes were prepared and used as catalysts in the reduction of p-nitrophenol (PNP in the aqueous phase and in the presence of sodium borohydride (NaBH4. Parameters such as the reaction temperature, substrate/NaBH4 molar ratio, and substrate/gold molar ratio were tested and evaluated. In this paper, we compare the catalytic reactivities of gold nanorods (AuNRs and gold nanospheres (AuNSs, both synthesized by the seed-mediated method in the presence of cetyltrimethyl ammonium bromide (CTAB. Physical-chemical parameters such as the apparent rate constant (kapp and activation energy (Ea of the reactions were obtained for both systems. We observed that the catalytic system based on AuNRs is the most active. These colloidal dispersions were investigated and fully characterized by ultraviolet-visible absorption spectroscopy (UV–Vis and transmission electron microscopy (TEM.

  1. Redução de amidas por boranos Reduction of amides by boranes

    Directory of Open Access Journals (Sweden)

    Antônio Flávio de Carvalho Alcântara

    2002-05-01

    Full Text Available Despite the fact that boranes are frequently used in amide reductions, the reaction mechanisms of the involved are note well known. This work presents the results of a bibliographic search on probable amide reduction mechanisms and an analysis of the existing literature. Steric and electronic effects were considered in light of reactivity since it could be concluded that the formation of intermediates and products depends mainly on the substitution patterns of both the boron and nitrogen atoms. Otherwise, results described in the literature for the reactions of boranes, sodium borohydride, lithium aluminum hydride, alkylboranes or haloboranes with others functional groups such as carboxylic acids, esters, ketones and alkenes were analysed with the aim to obtain something about the N-substituted amide reactions employing boranes.

  2. Reversible hydrogen storage materials

    Science.gov (United States)

    Ritter, James A [Lexington, SC; Wang, Tao [Columbia, SC; Ebner, Armin D [Lexington, SC; Holland, Charles E [Cayce, SC

    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.

  3. A twist on facial selectivity of hydride reductions of cyclic ketones: twist-boat conformers in cyclohexanone, piperidone, and tropinone reactions.

    Science.gov (United States)

    Neufeldt, Sharon R; Jiménez-Osés, Gonzalo; Comins, Daniel L; Houk, K N

    2014-12-05

    The role of twist-boat conformers of cyclohexanones in hydride reductions was explored. The hydride reductions of a cis-2,6-disubstituted N-acylpiperidone, an N-acyltropinone, and tert-butylcyclohexanone by lithium aluminum hydride and by a bulky borohydride reagent were investigated computationally and compared to experiment. Our results indicate that in certain cases, factors such as substrate conformation, nucleophile bulkiness, and remote steric features can affect stereoselectivity in ways that are difficult to predict by the general Felkin-Anh model. In particular, we have calculated that a twist-boat conformation is relevant to the reactivity and facial selectivity of hydride reduction of cis-2,6-disubstituted N-acylpiperidones with a small hydride reagent (LiAlH4) but not with a bulky hydride (lithium triisopropylborohydride).

  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. Enzymatic synthesis of tritium-labelled prostaglandin D[sub 2] and its conversion to other prostaglandins

    Energy Technology Data Exchange (ETDEWEB)

    Shram, S.I.; Lazurkina, T.Yu.; Shevchenko, V.P.; Nagaev, I.Yu.; Myasoedov, N.F. (AN SSSR, Moscow (Russian Federation). Inst. Molekulyarnoj Genetiki)

    1994-04-01

    The one-stage enzymatic synthesis of tritium-labelled prostaglandin D[sub 2] from labelled arachidonic acid was performed by using the enzyme system PGH-synthetase/PGH-PGD-isomerase. By enzymatic and chemical transformation of [[sup 3]H]PGD[sub 2] the following compounds were obtained: 15-keto-13,14-dihydro-[[sup 3]H]PGD[sub 2], 9[alpha],11[beta]-[[sup 3]H]PGF[sub 2], 9-deoxy-[Delta][sup 9]-[[sup 3]H]-PGD[sub 2] ([[sup 3]H]PGJ[sub 2]) and [Delta][sup 12]-13,14-dihydro-[[sup 3]H]PGJ[sub 2]. It was found that L-selectride is a more effective reducing agent than sodium borohydride in the synthesis of 9[alpha], 11[beta]-[[sup 3]H]PGF[sub 2]. (Author).

  6. Enzymatic synthesis of tritium-labelled prostaglandin D2 and its conversion to other prostaglandins

    International Nuclear Information System (INIS)

    Shram, S.I.; Lazurkina, T.Yu.; Shevchenko, V.P.; Nagaev, I.Yu.; Myasoedov, N.F.

    1994-01-01

    The one-stage enzymatic synthesis of tritium-labelled prostaglandin D 2 from labelled arachidonic acid was performed by using the enzyme system PGH-synthetase/PGH-PGD-isomerase. By enzymatic and chemical transformation of [ 3 H]PGD 2 the following compounds were obtained: 15-keto-13,14-dihydro-[ 3 H]PGD 2 , 9α,11β-[ 3 H]PGF 2 , 9-deoxy-Δ 9 -[ 3 H]-PGD 2 ([ 3 H]PGJ 2 ) and Δ 12 -13,14-dihydro-[ 3 H]PGJ 2 . It was found that L-selectride is a more effective reducing agent than sodium borohydride in the synthesis of 9α, 11β-[ 3 H]PGF 2 . (Author)

  7. Derivatives of 16alpha-hydroxy-dehydroepiandrosterone with an additional 7-oxo or 7-hydroxy substituent: synthesis and gas chromatography/mass spectrometry analysis.

    Science.gov (United States)

    Pouzar, Vladimír; Cerný, Ivan; Hill, Martin; Bicíková, Marie; Hampl, Richard

    2005-10-01

    Derivatives of 16alpha-hydroxy-dehydroepiandrosterone, which have an additional oxygen substituent at position 7 (oxo or hydroxy group), were synthesized. Firstly, 17,17-dimethoxyandrost-5-ene-3beta,16alpha-diyl diacetate was prepared and then oxidized with a complex of chromium(VI) oxide and 2,5-dimethylpyrazole to the respective 7-oxo derivative. This key intermediate was both deprotected or reduced by l-Selectride or sodium borohydride in the presence of cerium(III) chloride and then deprotected to give 7-oxo, 7alpha-hydroxy and 7beta-hydroxy derivatives of 16alpha-hydroxy-dehydroepiandrosterone. The target compounds were characterized by (1)H and (13)C NMR spectra and in the form of O-methyloxime-trimethylsilyl derivatives, by gas chromatography/mass spectrometry methods.

  8. Study of film graphene/graphene oxide obtained by partial reduction chemical of oxide graphite

    International Nuclear Information System (INIS)

    Gascho, J.L.S.; Costa, S.F.; Hoepfner, J.C.; Pezzin, S.H.

    2014-01-01

    This study investigated the morphology of graphene/graphene oxide film obtained by partial chemical reduction of graphite oxide (OG) as well as its resistance to solvents. Films of graphene/graphene oxide are great candidates for replacement of indium oxide doped with tin (ITO) in photoelectric devices. The OG was obtained from natural graphite, by Hummer's method modified, and its reduction is made by using sodium borohydride. Infrared spectroscopy analysis of Fourier transform (FTIR), Xray diffraction (XRD) and scanning electron microscopy, high-resolution (SEM/FEG) for the characterization of graphene/graphene oxide film obtained were performed. This film proved to be resilient, not dispersing in any of the various tested solvents (such as ethanol, acetone and THF), even under tip sonication, this resistance being an important property for the applications. Furthermore, the film had a morphology similar to that obtained by other preparation methods.(author)

  9. TiO{sub 2}/WO{sub 3}/Au/MWCNT composite materials for photocatalytic hydrogen production: Advantages and draw-backs

    Energy Technology Data Exchange (ETDEWEB)

    Pap, Zsolt [Research Group of Environmental Chemistry, University of Szeged, Tisza Lajos krt. 103, H-6720 Szeged (Hungary); Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Arany Janos 11, RO-400028 Cluj-Napoca (Romania); Faculty of Physics, Babes-Bolyai University, M. Kogalniceanu 1, RO-400084 Cluj-Napoca (Romania); Karacsonyi, Eva; Mogyorosi, Karoly; Dombi, Andras [Research Group of Environmental Chemistry, University of Szeged, Tisza Lajos krt. 103, H-6720 Szeged (Hungary); Baia, Lucian [Faculty of Physics, Babes-Bolyai University, M. Kogalniceanu 1, RO-400084 Cluj-Napoca (Romania); Pop, Lucian Cristian [Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Arany Janos 11, RO-400028 Cluj-Napoca (Romania); Faculty of Physics, Babes-Bolyai University, M. Kogalniceanu 1, RO-400084 Cluj-Napoca (Romania); Danciu, Virginia [Faculty of Chemistry and Chemical Engineering, Babes-Bolyai University, Arany Janos 11, RO-400028 Cluj-Napoca (Romania); Hernadi, Klara [Department of Applied and Environmental Chemistry, University of Szeged, Rerrich ter 1, H-6720 Szeged (Hungary)

    2012-12-15

    TiO{sub 2}/WO{sub 3}/Au/MWCNT composite materials were obtained using different commercial titanias (Aldrich Anatase, Aldrich Rutile, and Evonik Aeroxide P25) and Aldrich WO{sub 3}. 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)

  10. Synthesis of 1-dodecanethiol-capped Ag nanoparticles and their high catalytic activity

    Science.gov (United States)

    Zhang, Danhui; Yang, Youbo

    2017-01-01

    Silver nanoparticles, which were produced by the borohydride reduction of silver nitrate, were stabilized by means of 1-dodecanethiol providing sulfur atom in two-phase system involving water and organic solvent (such as toluene, chloroform and hexane). Different organic solvent played a major role in the particle size of silver nanoparticles. These silver nanoparticles synthesized in the three different organic solvent were characterized by X-ray Diffraction, transmission electron microscopy and ultraviolet-visible absorption spectroscopy. The results indicate that the particles size of silver nanoparticles formed in three organic solvents was different. Furthermore, 1-dodecanethiol-capped silver nanoparticles were found to serve as effective catalysts to activate the reduction of 4-nitrophenol (4NP) in the presence of NaBH4, where the size of silver nanoparticles played the determining role in catalytic activity.

  11. Green synthesis of the Pd nanoparticles supported on reduced graphene oxide using barberry fruit extract and its application as a recyclable and heterogeneous catalyst for the reduction of nitroarenes.

    Science.gov (United States)

    Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Alizadeh, Mohammad; Bagherzadeh, Mojtaba

    2016-03-15

    Through this manuscript the green synthesis of palladium nanoparticles supported on reduced graphene oxide (Pd NPs/RGO) under the mild conditions through reduction of the graphene oxide and Pd(2+) ions using barberry fruit extract as reducing and stabilizing agent is reported. The as-prepared Pd NPs/RGO was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The Pd NPs/RGO could be used as an efficient and heterogeneous catalyst for reduction of nitroarenes using sodium borohydride in an environmental friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled multiple times without any significant loss of its catalytic activity. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. 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.

  13. 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.

  14. 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.

  15. Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.

    Science.gov (United States)

    Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

    2013-12-01

    Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Magnetic nanofilms of nickel prepared at the liquid-liquid interface

    International Nuclear Information System (INIS)

    Varghese, Neenu; Rao, C.N.R.

    2011-01-01

    Highlights: → Formation of nickel thinfims at the organic-aqueous interface at room temperature. → Thickness of nanofilm is ∼20 nm. → Ni nanofilms exhibit superparamagnetic behavior. → Thicker Ni films are obtained at a higher temperature (60 o C). -- Abstract: Thin films of metallic nickel with a thickness of the order of 20 nm have been prepared at the organic-aqueous interface at room temperature by the reaction of nickel cupferronate [Ni(C 6 H 5 N 2 O 2 ) 2 ] in toluene medium and sodium borohydride (NaBH 4 ) in aqueous medium. The films were characterized with transmission electron microscopy, scanning electron microscopy and atomic force microscopy. Thicker Ni films could be prepared by carrying out the reaction at the interface at 60 o C. The Ni nanofilms exhibit superparamagnetic behavior.

  17. Performance prediction of scalable fuel cell systems for micro-vehicle applications

    Science.gov (United States)

    St. Clair, Jeffrey Glen

    Miniature (fuel cells consuming high energy density fuels. This thesis surveys miniature fuel cell technologies and identifies direct methanol and sodium borohydride technologies as especially promising at small scales. A methodology for estimating overall system-level performance that accounts for the balance of plant (i.e. the extra components like pumps, blowers, etc. necessary to run the fuel cell system) is developed and used to quantify the performance of two direct methanol and one NaBH4 fuel cell systems. Direct methanol systems with water recirculation offer superior specific power (400 mW/g) and specific energy at powers of 20W and system masses of 150g. The NaBH4 fuel cell system is superior at low power (fuel.

  18. 99mTc labeling of the scorpion (Tityus serrulatus) antivenom

    International Nuclear Information System (INIS)

    Cardoso, D.S.; Nunan, E.A.; Toledo, V.P.C.P.; Moraes-Santos, T.; Cardoso, V.N.

    2008-01-01

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

  19. Determination of thymine glycol residues in irradiated or oxidized DNA by formation of methylglyceric acid

    International Nuclear Information System (INIS)

    Schellenberg, K.A.; Shaeffer, J.

    1986-01-01

    Treatment of DNA solutions with X-irradiation various oxidants including hydrogen peroxide plus ferrous ion, hydrogen peroxide plus copper ion and ascorbate, permanganate, or sonication in the presence of dissolved oxygen all produced varying amounts of thymine glycol residues. After denaturing the DNA with heat, the glycol residues were reduced and labeled at the 6 position with tritium- labeled sodium borohydride. Subsequent reaction with anhydrous methanolic HCl gave a quantitative yield of the methyl ester of methylglyceric acid, which was determined by thin layer chromatography. The method, developed using thymidine as a model, was used to ascertain the requirements for glycol formation in DNA. It was shown that hydroxyl radical generating systems, permanganate, X-irradiation, or sonication in presence of oxygen were required, but hydrogen peroxide in the absence of iron or copper and ascorbate was inactive. Application to determination of DNA damage in vivo is being explored

  20. Synthesis and characterization of silver and gold nanoparticles in ionic liquid.

    Science.gov (United States)

    Singh, Prashant; Kumari, Kamlesh; Katyal, Anju; Kalra, Rashmi; Chandra, Ramesh

    2009-07-01

    In this paper, we report the reduction of silver and gold salts by methanolic solution of sodium borohydride in tetrazolium based ionic liquid as a solvent at 30 degrees C leads to pure phase of silver and gold nanoparticles. Silver and gold nanoparticles so-prepared were well characterized by powder X-ray diffraction measurements (XRD), transmission electron microscopy (TEM) and QELS. XRD analysis revealed all relevant Bragg's reflection for crystal structure of silver and gold metal. XRD spectra also revealed no oxidation of silver nanoparticles to silver oxide. TEM showed nearly uniform distribution of the particles in methanol and it was confirmed by QELS. Silver and gold nanoparticles in ionic liquid can be easily synthesized and are quite stable too.

  1. Synthesis, characterization and spectroscopic studies of the dihydrobis(1,2,3-benzotriazolylborate anion and its complexes with MCl2·py2

    Directory of Open Access Journals (Sweden)

    KHWAJA S. SIDDIQI

    2006-11-01

    Full Text Available The preparation of sodium dihydrobis(1,2,3-benzotriazolylborate was realised by refluxing one mole of sodium borohydride with two moles of 1,2,3-benzotriazole in toluene over a period of 12 h. Its complexes with MCl2·py2 [whereM=Mn(II, Fe(II, Co(II, Ni(II, Cu(II and py=pyridine] were characterized by elemental analysis as well as magnetic, spectroscopic and conductivity measurements. On the basis of these studies, it is proposed that the geometry of all the complexes is octahedral. The ligand field parameters 10 Dq, B and b show extensive overlap between the M–L orbital. The molar conductance of 10-3 M solutions of the complexes in DMSO suggest them to be non-ionic in nature.

  2. Metallization of DNA hydrogel: application of soft matter host for preparation and nesting of catalytic nanoparticles

    Science.gov (United States)

    Zinchenko, Anatoly; Che, Yuxin; Taniguchi, Shota; Lopatina, Larisa I.; G. Sergeyev, Vladimir; Murata, Shizuaki

    2016-07-01

    Nanoparticles (NPs) of Au, Ag, Pt, Pd, Cu and Ni of 2-3 nm average-size and narrow-size distributions were synthesized in DNA cross-linked hydrogels by reducing corresponding metal precursors by sodium borohydride. DNA hydrogel plays a role of a universal reactor in which the reduction of metal precursor results in the formation of 2-3 nm ultrafine metal NPs regardless of metal used. Hydrogels metallized with various metals showed catalytic activity in the reduction of nitroaromatic compounds, and the catalytic activity of metallized hydrogels changed as follows: Pd > Ag ≈ Au ≈ Cu > Ni > Pt. DNA hydrogel-based "soft catalysts" elaborated in this study are promising for green organic synthesis in aqueous media as well as for biomedical in vivo applications.

  3. Cytosine-assisted synthesis of gold nanochains and gold nanoflowers for the construction of a microperoxidase-11 based amperometric biosensor for hydrogen peroxide

    International Nuclear Information System (INIS)

    Zhang, Qian-Li; Zhou, Dan-Ling; Wang, Ai-Jun; Qin, Su-Fang; Feng, Jiu-Ju; Li, Yong-Fang

    2014-01-01

    A simple method was developed for synthesis of network-like gold nanochains and gold nanoflowers in the presence of cytosine by reduction of tetrachloroauric acid with sodium borohydride and ascorbic acid, respectively. The resulting gold nanocrystals were coated with microperoxidase-11 via electrostatic interactions. Electrodes modified with protein-coated gold nanochains or nanoflowers display well-defined and quasi reversible redox peaks and enhanced high electrocatalytic activity toward the reduction of H 2 O 2 that is due to direct electron transfer to the protein. The effects were exploited for the amperometric detection of H 2 O 2 with a linear response from 0.5 μM to 0.13 mM (for the gold nanochains) and from 1.0 μM to 0.11 mM (for the gold nanoflowers), respectively. The sensor shows lower detection limit and faster response time than sensors based on the use of spherical gold nanoparticles. (author)

  4. 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.

  5. Concentration-dependent optical properties of TGA stabilized CdTe Quantum dots synthesized via the single injection hydrothermal method in the ambient environment

    Science.gov (United States)

    Jai Kumar, B.; Mahesh, H. M.

    2017-04-01

    Thioglycolic acid (TGA) stabilized aqueous CdTe Quantum dots (QDs) were synthesized using a facile, cost efficient Single Injection Hydrothermal (SIH) method. The complete preparation of precursors and growth of QDs was carried out in the ambient environment without inter gas protection. The Cadmium and Tellurium precursors were prepared from cadmium nitrate and elemental tellurium powder with sodium borohydride as reducing agent respectively. A systematic investigation was carried out in order to study the effect of 0.04M and 0.08M TGA concentration on ease synthesis, stability and size-tunable optical absorbance, bandgap, photoluminescence (PL) and Quantum yield (QY) of CdTe QDs. The Structure of QDs was verified by XRD and optical properties by absorbance and PL spectra. Experimental results revealed that the 0.08M TGA QDs possess good chemical and optical stability with high luminescence and decent QY, ready to use in optoelectronics, photovoltaic and biological application.

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

    International Nuclear Information System (INIS)

    Wilson, J.G.; Anisuzzaman, A.K.M.; Soloway, A.H.; Alam, F.

    1992-01-01

    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

  7. 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.

  8. Characterizing and Diminishing Autofluorescence in Formalin-fixed Paraffin-embedded Human Respiratory Tissue

    Science.gov (United States)

    Davis, A. Sally; Richter, Anke; Becker, Steven; Moyer, Jenna E.; Sandouk, Aline; Skinner, Jeff

    2014-01-01

    Tissue autofluorescence frequently hampers visualization of immunofluorescent markers in formalin-fixed paraffin-embedded respiratory tissues. We assessed nine treatments reported to have efficacy in reducing autofluorescence in other tissue types. The three most efficacious were Eriochrome black T, Sudan black B and sodium borohydride, as measured using white light laser confocal Λ2 (multi-lambda) analysis. We also assessed the impact of steam antigen retrieval and serum application on human tracheal tissue autofluorescence. Functionally fitting this Λ2 data to 2-dimensional Gaussian surfaces revealed that steam antigen retrieval and serum application contribute minimally to autofluorescence and that the three treatments are disparately efficacious. Together, these studies provide a set of guidelines for diminishing autofluorescence in formalin-fixed paraffin-embedded human respiratory tissue. Additionally, these characterization techniques are transferable to similar questions in other tissue types, as demonstrated on frozen human liver tissue and paraffin-embedded mouse lung tissue fixed in different fixatives. PMID:24722432

  9. 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.

  10. Phospholipid-assisted synthesis of size-controlled gold nanoparticles

    International Nuclear Information System (INIS)

    He Peng; Zhu Xinyuan

    2007-01-01

    Morphology and size control of gold nanoparticles (AuNPs) by phospholipids (PLs) has been reported. It was found that gold entities could form nanostructures with different sizes controlled by PLs in an aqueous solution. During the preparation of 1.5 nm gold seeds, AuNPs were obtained from the reduction of gold complex by sodium borohydride and capped by citrate for stabilization. With the different ratios between seed solution and growth solution, which was composed by gold complex and PLs, gold seeds grew into larger nanoparticles step by step until enough large size up to 30 nm. The main discovery of this work is that common biomolecules, such as PLs can be used to control nanoparticle size. This conclusion has been confirmed by transmission electron micrographs, particle size analysis, and UV-vis spectra

  11. Complex Metal Hydrides for hydrogen storage and solid-state ion conductors

    DEFF Research Database (Denmark)

    Payandeh GharibDoust, SeyedHosein

    Renewable energy, such as sun and wind, are sustainable and clean sources of energy for the future but are unevenly distributed both over time and geographically. Therefore, this type of energy must be converted to a form that can be stored and two of the most promising options are hydrogen...... and electricity in batteries. However, both hydrogen and electricity must be stored in a very dense way to be useful, e.g. for mobile applications. Complex metal hydrides have high hydrogen density and have been studied during the past twenty years in hydrogen storage systems. Moreover, they have shown high ionic...... conductivities which promote their application as solid electrolytes in batteries. This dissertation presents the synthesis and characterization of a variety of complex metal hydrides and explores their hydrogen storage properties and ionic conductivity. Five halide free rare earth borohydrides RE(BH4)3, (RE...

  12. SERS studies on the interaction between UO22+ and PVP-stabilized silver nanoparticles

    International Nuclear Information System (INIS)

    Roy, M.; Tyagi, A.K.; Kumar, Rakesh; Pandey, A.K.; Goswami, A.

    2010-01-01

    Interaction between uranyl (UO 2 2+ ) ions and silver nanoparticles (Ag-nps) stabilized by suitable polymeric capping agents has been studied in aqueous phase using surface enhanced resonance Raman spectroscopy technique (SERS). Polyvinylpyrrolidone (PVP) stabilized Ag-nps were synthesized by dissolving in water appropriate amount of PVP and AgNO 3 along with a suitable reducing agent in the form of either formamide or sodium borohydride. The solution was vigorously stirred for 5h and finally nanoparticle sols were obtained. A series of analyte samples was prepared by adding an appropriate amount of silver sol to different volumes of uranyl stock solution prepared at pH=3. The solutions were then drop cast on glass slides and dried in air. Preliminary results on drop-cast samples are presented here

  13. Surface plasmon resonance sensor based on golden nanoparticles and cold vapour generation technique for the detection of mercury in aqueous samples

    Science.gov (United States)

    Castillo, Jimmy; Chirinos, José; Gutiérrez, Héctor; La Cruz, Marie

    2017-09-01

    In this work, a surface plasmon resonance sensor for determination of Hg based on golden nanoparticles was developed. The sensor follows the change of the signal from solutions in contact with atomic mercury previously generated by the reaction with sodium borohydride. Mie theory predicts that Hg film, as low as 5 nm, induced a significant reduction of the surface plasmon resonance signal of 40 nm golden nanoparticles. This property was used for quantification purposes in the sensor. The device provide limits of detection of 172 ng/L that can compared with the 91 ng/L obtained with atomic fluorescence, a common technique used for Hg quantification in drinking water. This result was relevant, considering that it was not necessary to functionalize the nanoparticles or use nanoparticles deposited in a substrate. Also, thanks that Hg is released from the matrix, the surface plasmon resonance signal was not affected by concomitant elements in the sample.

  14. Metallization of DNA hydrogel: application of soft matter host for preparation and nesting of catalytic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zinchenko, Anatoly, E-mail: zinchenko@urban.env.nagoya-u.ac.jp; Che, Yuxin; Taniguchi, Shota [Nagoya University, Graduate School of Environmental Studies (Japan); Lopatina, Larisa I.; Sergeyev, Vladimir G. [Moscow State University, Department of Chemistry (Russian Federation); Murata, Shizuaki [Nagoya University, Graduate School of Environmental Studies (Japan)

    2016-07-15

    Nanoparticles (NPs) of Au, Ag, Pt, Pd, Cu and Ni of 2–3 nm average-size and narrow-size distributions were synthesized in DNA cross-linked hydrogels by reducing corresponding metal precursors by sodium borohydride. DNA hydrogel plays a role of a universal reactor in which the reduction of metal precursor results in the formation of 2–3 nm ultrafine metal NPs regardless of metal used. Hydrogels metallized with various metals showed catalytic activity in the reduction of nitroaromatic compounds, and the catalytic activity of metallized hydrogels changed as follows: Pd > Ag ≈ Au ≈ Cu > Ni > Pt. DNA hydrogel-based “soft catalysts” elaborated in this study are promising for green organic synthesis in aqueous media as well as for biomedical in vivo applications.Graphical Abstract.

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

    International Nuclear Information System (INIS)

    Kravchenko, T.B.; Bel'tyukova, S.V.; Kononenko, L.I.; Poluehktov, N.S.

    1982-01-01

    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% [ru

  16. Synthesis of new 3,5-disubstituted-1,2,4-triazoles and evaluation of antibacterial, antiurease and antioxidant activities

    International Nuclear Information System (INIS)

    Gumrukcuoglu, N.; Sokmen, B.B.; Ugras, S.

    2016-01-01

    Acylhydrazone 2 was synthesized by the condensation of iminoester hydrochloride 1 with acyl hydrazine. The treatment of acylhydrazone with hydrazine hydrate afforded 4-amino-3,5-dialkyl-1,2,4- triazole 3. The treatment of compound 3 with various aromatic aldehydes resulted in the formation of 4-arylidenamino-3,5-dialkyl-1,2,4-triazoles 4a-c. Sodium borohydride reduction of 4-arylidenamino derivatives afforded 4-alkylamino-3,5-dialkyl-1,2,4- triazoles 5a-c. The obtained products were identified by FTIR, /sup 1/H-NMR, /sup 13/C-NMR, Mass spectroscopic and elemental analysis. A series of compounds were evaluated for their, antibacterial, antiurease, antioxidant activities. The results showed that the synthesized new compounds had effective antibacterial, antioxidant, antiurease activities. (author)

  17. Stabilization of triangular and heart-shaped plane silver nanoparticles using 2-thiobarbituric acid

    Science.gov (United States)

    Botasini, Santiago; Dalchiele, Enrique A.; Benech, Juan Claudio; Méndez, Eduardo

    2011-07-01

    The synthesis of silver non-spherical structures like nanotriangles, nanohexagons, and nanodisks, etc., follows a kinetic control that strongly depends on the nature and concentration of the reagents. By using sodium borohydride in a low molar ratio respect to the Ag+ source for working under kinetic control, it was possible to obtain different plane nanostructures which in turn could be stabilized by the use of the substituted mercaptopyrimidine 2-thiobarbituric acid. In addition, the use of this thiol allowed the stabilization of an unreported shape that could be an intermediate structure in the shape evolution of nanotriangles through nanodisks. This new particle, with 200-300 nm length and 6 nm height, is named "nanoheart" due to its heart-shaped resemblance.

  18. Stabilization of triangular and heart-shaped plane silver nanoparticles using 2-thiobarbituric acid

    International Nuclear Information System (INIS)

    Botasini, Santiago; Dalchiele, Enrique A.; Benech, Juan Claudio; Méndez, Eduardo

    2011-01-01

    The synthesis of silver non-spherical structures like nanotriangles, nanohexagons, and nanodisks, etc., follows a kinetic control that strongly depends on the nature and concentration of the reagents. By using sodium borohydride in a low molar ratio respect to the Ag + source for working under kinetic control, it was possible to obtain different plane nanostructures which in turn could be stabilized by the use of the substituted mercaptopyrimidine 2-thiobarbituric acid. In addition, the use of this thiol allowed the stabilization of an unreported shape that could be an intermediate structure in the shape evolution of nanotriangles through nanodisks. This new particle, with 200–300 nm length and 6 nm height, is named “nanoheart” due to its heart-shaped resemblance.

  19. 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.

  20. Surface analysis by Fourier-transform infrared (FTIR) spectroscopy

    International Nuclear Information System (INIS)

    Powell, G.L.; Smyrl, N.R.; Fuller, E.L.

    1981-01-01

    A diffuse-reflectance capability for the Fourier transform infrared spectrometer at the Y-12 Plant Laboratory has been implemented. A sample cell with a 25 to 400 0 C temperature-controlled sample stage and an ultrahigh-vacuum-to-atmospheric pressure gas-handling capability has been developed. Absorbance of light from the spectrometer beam, resulting from the beam being scattered from a powder sample, can be measured. This capability of detecting molecular species on and in powders is to be used to study chemisorption on actinide and rare-earth metals, alloys, and compounds. Cell design is described along with experiments demonstrating its performance in detecting moisture absorption on uranium oxide, moisture and carbon dioxide absorption on the lithium hydride/hydroxide system, and carbon dioxide absorption on potassium borohydride. 13 figures

  1. The Catalytic Behaviour of NanoAg@montmorillonite Composite Materials

    Science.gov (United States)

    Karlíková, Martina; Kvítek, Libor; Prucek, Robert; Panáček, Aleš; Filip, Jan; Pechoušek, Jiří; Adegboyega, Nathaniel F.

    The preparation of nanoAg@montmorillonite composite materials and their catalytic activity is reported in this article. The nanoAg@montmorillonite composite materials were prepared by the adsorption of silver NPs, with an average size about 30 nm, from their aqueous dispersion onto two types of montmorillonite with different chemical composition. Silver NPs were prepared via modified Tollens process, which involves the reduction of [Ag(NH3)2]+ complex cation by maltose. The amount of silver NPs anchored onto the MMT surfaces was determined by UV-VIS spectroscopy; the decrease in absorbance of the dispersion after the adsorption was monitored. Prepared nanocomposite materials were subsequently characterized by means of transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). The reduction of 4-nitrophenol by sodium borohydride was chosen to examine the catalytic properties of the synthesized silver nanocomposite materials.

  2. Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

    Directory of Open Access Journals (Sweden)

    Kasper T. Møller

    2017-10-01

    Full Text Available Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds, which have fascinating structures, compositions and properties. Complex metal hydrides are a rapidly expanding class of materials, approaching multi-functionality, in particular within the energy storage field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted how complex metal hydrides may act in an integrated setup with a fuel cell. This review focuses on the unique properties of light element complex metal hydrides mainly based on boron, nitrogen and aluminum, e.g., metal borohydrides and metal alanates. Our hope is that this review can provide new inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy.

  3. Glycoprotein Ib and glycoprotein IX in human platelets are acylated with palmitic acid through thioester linkages

    International Nuclear Information System (INIS)

    Muszbek, L.; Laposata, M.

    1989-01-01

    The glycoprotein (GP) Ib-IX complex is a major component of the platelet membrane which mediates adhesion of platelets to exposed subendothelium. GP Ib is a heterodimer with a large alpha chain (Mr = 135,000-145,000) and small beta chain (Mr = 22,000-27,000) linked by a disulfide bond(s). GP Ib is bound in a noncovalent 1:1 complex with GP IX (Mr = 17,000-22,000). We labeled isolated human platelets with [3H] palmitate or surface-labeled platelet membrane glycoproteins with sodium periodate-[3H]sodium borohydride and immunoprecipitated the GP Ib-IX complex from radiolabeled platelet lysates using a mouse monoclonal antibody (SZ.1) which recognizes the intact complex. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitates from [3H]palmitate-labeled platelets revealed two radiolabeled bands under reducing conditions at 24 and 19 kDa and two bands under nonreducing conditions at 170 and 19 kDa. As demonstrated by the parallel analysis of immunoprecipitates from periodate-[3H]sodium borohydride-labeled platelets, the [3H]palmitate-labeled bands obtained under reducing conditions corresponded to GP Ib beta and GP IX and the ones obtained under nonreducing conditions to intact GP Ib and GP IX, respectively. Using alkaline methanolysis followed by high pressure liquid chromatography analysis of the methanolysis products, we demonstrated that the radioactivity associated with the GP Ib-IX complex from [3H]palmitate-labeled platelets was, in fact, covalently bound [3H]palmitate in ester linkage to protein. The protein-fatty acid linkage was also disrupted by hydroxylamine at neutral pH. Thus, this study demonstrates that GP Ib beta and GP IX in human platelets are both fatty acid-acylated with palmitate through thioester linkages

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

    International Nuclear Information System (INIS)

    Brandalise, Michele

    2012-01-01

    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)

  5. Boron-Based Hydrogen Storage: Ternary Borides and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John J. [HRL Laboratories, LLC, Malibu, CA (United States)

    2016-04-28

    DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slow rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.

  6. Reductive Alkaline Release of N-Glycans Generates a Variety of Unexpected, Useful Products.

    Science.gov (United States)

    Figl, Rudolf; Altmann, Friedrich

    2018-02-01

    Release of O-glycans by reductive β-elimination has become routine in many glyco-analytical laboratories and concomitant release of N-glycans has repeatedly been observed. Revisiting this somewhat forgotten mode of N-glycan release revealed that all kinds of N-glycans including oligomannosidic and complex-type N-glycans from plants with 3-linked fucose and from mammals with or without 6-linked fucose and with sialic acid could be recovered. However, the mass spectra of the obtained products revealed very surprising facts. Even after 16 h incubation in 1 M sodium borohydride, a large part of the glycans occurred in reducing form. Moreover, about one third emerged in the form of the stable amino-functionalized 1-amino-1-deoxy-glycitol. When avoiding acidic conditions, considerable amounts of glycosylamine were observed. In addition, a compound with a reduced asparagine and de-N-acetylation products, in particular of sialylated glycans, was seen. The relative yields of the products reducing glycosylamine, reducing N-glycan, 1-amino-1-deoxy-glycitol or glycitol could be controlled by the release conditions, foremost by temperature and borohydride concentration. Thus, chemical release of N-glycans constitutes a cost-saving alternative to enzymatic hydrolysis for the preparation of precursors for the production of reference compounds for various formats of N-glycan analysis. Moreover, it allows to obtain a stable amino-functionalized glycan derivative, which can be employed to construct glycan arrays or affinity matrices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. A gas-phase chemiluminescence-based analyzer for waterborne arsenic

    Science.gov (United States)

    Idowu, A.D.; Dasgupta, P.K.; Genfa, Z.; Toda, K.; Garbarino, J.R.

    2006-01-01

    We show a practical sequential injection/zone fluidics-based analyzer that measures waterborne arsenic. The approach is capable of differentiating between inorganic As(III) and As(V). The principle is based on generating AsH 3 from the sample in a confined chamber by borohydride reduction at controlled pH, sparging the chamber to drive the AsH3 to a small reflective cell located atop a photomultiplier tube, allowing it to react with ozone generated from ambient air, and measuring the intense chemiluminescence that results. Arsine generation and removal from solution results in isolation from the sample matrix, avoiding the pitfalls encountered in some solution-based analysis techniques. The differential determination of As(III) and As(V) is based on the different pH dependence of the reducibility of these species to AsH3. At pH ???1, both As(III) and As(V) are quantitatively converted to arsine in the presence of NaBH4. At a pH of 4-5, only As(III) is converted to arsine. In the present form, the limit of detection (S/N = 3) is 0.05 ??g/L As at pH ???1 and 0.09 ??g/L As(III) at pH ???4-5 for a 3-mL sample. The analyzer is intrinsically automated and requires 4 min per determination. It is also possible to determine As(III) first at pH 4.5 and then determine the remaining As in a sequential manner; this requires 6 min. There are no significant practical interferences. A new borohydride solution formulation permits month-long reagent stability. ?? 2006 American Chemical Society.

  8. 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)

  9. Electrochemical hydrogen Storage Systems

    International Nuclear Information System (INIS)

    Macdonald, Digby

    2010-01-01

    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

  10. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Craig [Univ. of Hawaii, Honolulu, HI (United States); McGrady, Sean [Univ. of New Brunswick, Fredericton NB (Canada); Severa, Godwin [Univ. of Hawaii, Honolulu, HI (United States); Eliseo, Jennifer [Univ. of Hawaii, Honolulu, HI (United States); Chong, Marina [Univ. of Hawaii, Honolulu, HI (United States)

    2013-05-31

    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 (75-190 º C). However, in situ IR studies in tandem with thermal gravimetric analysis have shown that about 0.5 equivalents of diborane are released during the

  12. Microfluidic platforms and fundamental electrocatalysis studies for fuel cell applications

    Science.gov (United States)

    Cohen, Jamie Lee

    The fabrication and testing of a planar membraneless microchannel fuel cell, based on a silicon microchannel, is described in detail. Laminar flow of fuel and oxidant streams, one on top of the other, prevents fuel crossover while allowing ionic transport at the interface between the two solutions. By employing laminar flow, the useful functions of a membrane are retained, while bypassing its inherent limitations. The planar design maximizes the anode and cathode areas, and elimination of the membrane affords broad flexibility in the choice of fuel and oxidant. Fuels including formic acid, methanol, ethanol, sodium borohydride and hydrogen were tested along with oxidants such as oxygen, hydrogen peroxide and potassium permanganate. Steps taken to improve voltage, current density, and overall power output have been addressed, including the testing of a dual electrolyte system and the use of micro-patterned electrode surfaces to enhance fuel utilization. As the complexity of the fuels studied in the microchannel fuel cell increased, it was imperative to characterize these fuels using electrochemical techniques prior to utilization in the fuel cell. The oxidation pathway of the liquid fuel methanol was studied rigorously because of its importance for micro-fuel cell applications. Activation energies for methanol oxidation at a Ptpoly surface were determined using electrochemical techniques, providing a benchmark for the comparison of activation energies of other Pt-based electrocatalysts for methanol oxidation at a given potential. A protocol to obtain Ea values was established in three different electrolytes and experimental parameters that influence the magnitude of these values are discussed in detail. The oxidation pathways of sodium borohydride were also examined at Au, Pt, and Pd surfaces using cyclic voltammetry, chronoamperometry, and rotating disk electrode voltammetry. In addition to studies on bulk Ptpoly surfaces, new bulk intermetallic catalysts were

  13. 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

  14. 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

  15. SYNTHESIS AND PROPERTIES OF 5-BROM- AND 5-CHLOROSUBSTITUTED trans-ACENAPHTHENE-1,2-DIOLS

    Directory of Open Access Journals (Sweden)

    V. V. Tarasyuk

    2017-09-01

    Full Text Available We carried out transformations that describe the preparation of an unsubstituted trans-acenaphthene-1,2-diol using 5-bromo- and 5-chloro-substituted starting materials. Thus, by the reflux of trans-1,2,5-tribromacenaphthene and 1,2-dibromo-5-chlorocenaphthene in water we obtained the corresponding 1,2-diols, which are considered to be cis-isomers by melting points and NMR 1H-spectra. So hydrolysis of trans-1,2,5-tribromo- and 1,2-dibromo-5-chloroacenaphthenes leads to very moderate yields of 1,2-diols (25-26% with undesired cis-stereoselectivity. By the reaction of 5-bromo- and 5-chlorocenaphthylenes with iodine and silver benzoate in benzene followed by hydrolysis, we obtained mixtures of cis- and trans-1,2-diols which were separated chromatographically and trans-isomers of 5-bromo- and 5-chloro-acenaphthene-1,2-diols were firstly isolated. The yield of trans-diols was low (10-15%, which led us to the search for a convenient method for preparation of trans-isomers. We found this method using the reduction reaction of 5-bromoacenaphthenequinone, replacing the explosive and non-selective reductant lithium aluminum hydride by a more selective and easy-to-handle sodium borohydride in isopropanol. Reduction of 5-bromocenaphthenequinone with sodium borohydride leads to a substantially pure trans-5-bromoacenaphthen-1,2-diol in a rather high yield (57% after re-crystallization.trans-5-Bromo- and 5-chloroacenaphthene-1,2-diols were analyzed by the complex of physical and chemical methods. It is shown that the trans-5-bromo- and 5-chloroacenaphthen-1,2-diols have essentially the same mass spectra with cis isomers, but substantially differ from them by melting points, IR and 1H NMR spectra. Melting points of trans-diols are generally lower than of cis-diols. In IR spectra cis-doils have two characteristic bands of O-H groups (due to association via intramolecular and intermolecular hydrogen bonds whereas transisomers have only one broad band (only

  16. 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

  17. 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.

  18. 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.

  19. Generation and thermally adjustable catalysis of silver nanoparticle immobilized temperature-sensitive nanocomposite

    Science.gov (United States)

    Xu, Jun; Zhou, Tao; Jia, Lei; Shen, Xiaoke; Li, Xiaohui; Li, Huijun; Xu, Zhouqing; Cao, Jianliang

    2017-03-01

    The rise in environmental issues due to the catalytic degradation of pollutants in water has received much attention. In this report, a facile method was developed for the generation of a novel thermosensitive Ag-decorated catalyst, SiO2@PNIPAM@Ag (the average particle size is around 540 nm), through atom transfer radical polymerization (ATRP) and mild reducing reactions. First, poly(N-isopropylacrylamide) (PNIPAM) was used to create a shell around mercapto-silica spheres that allowed for enhanced catalyst support dispersion into water. Second, through a mild reducing reaction, these Ag nanoparticles (NPs) were then anchored to the surface of SiO2@PNIPAM spheres. The resulting catalyst revealed catalytic activity to degrade various nitrobenzenes and organic dyes in an aqueous solution with sodium borohydride (NaBH4) at ambient temperature. The catalytic activity can be adjusted in different temperatures through the aggregation or dispersion of Ag catalyst on the polymer supporters, which is due to the thermosensitive PNIPAM shell. The ease of preparation and efficient catalytic activity of the catalyst can make it a promising candidate for the use in degrading organic pollutants for environmental remediation.

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

    International Nuclear Information System (INIS)

    Daud, M.; Khan, Z.; Ashgar, A.; Danish, M. I.; Qazi, I. A.

    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 X-ray florescence techniques were utilized for characterization of bimetallic Fe/Pt nanoparticles. Optimum dose, ph, temperature, and contact time were determined for removal through batch tests, both for metal based nanoparticles and anionic exchange resin. Adsorption data fitted well the Langmuir isotherm and conformed to the pseudo first-order kinetic model. Results indicated 97% reduction in nitrate by 0.25 mg/L of Fe/Pt nanoparticles at ph 7 and 83% reduction in nitrate was observed using 0.50 mg/L anionic exchange resins at ph 4 and contact time of one hour. Overall, Fe/Pt bimetallic nanoparticles demonstrated greater removal efficiency due to the small particle size, extremely large surface area (627 m 2 /g), and high adsorption capacity.

  1. Capillary electrophoresis-driven synthesis of water-soluble CdTe quantum dots in nanoliter scale

    Science.gov (United States)

    Nejdl, Lukas; Hynek, David; Adam, Vojtech; Vaculovicova, Marketa

    2018-04-01

    ‘Green nanotechnology’ is a term used for the design of nanomaterials and processes that reduce or eliminate the use and/or generation of hazardous substances. In this paper, a capillary electrophoresis (CE)-driven synthesis of CdTe quantum dots (QDs) and their subsequent conjugation with a metal-binding protein metallothionein (isofom MT1) is reported. Even though the toxic materials (cadmium and potassium borohydride) were used for synthesis, the proposed method can be labeled as ‘environmentally friendly’ because the whole process (synthesis of QDs and MT1 conjugation) was carried out under mild conditions: ultra-low volume (nanoliter scale), relatively low temperature (50 °C), atmospheric pressure, and completed in a short time (under 90 s). Prepared QDs were also characterized by classical fluorescence spectroscopy and transmission electron microscopy. This study opens up new possibilities for the utilization of classical CE in the synthesis of nanoparticles and on-line labeling of biomolecules in the nanoliter scale in short period of time.

  2. Protein-directed gold nanoparticles with excellent catalytic activity for 4-nitrophenol reduction.

    Science.gov (United States)

    Liu, Kewei; Han, Lei; Zhuang, Junyang; Yang, Da-Peng

    2017-09-01

    To explore high-performance noble metal nanomaterials for the reduction of the biotoxin 4-nitrophenol (4-NP) in medicine, we developed a green synthesis strategy of bovine serum albumin-stabilized Au nanoparticles (Au@BSA NPs). The as-synthesized Au@BSA NPs were characterized by ultraviolet-visible absorption spectrum, fourier transformed infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The functional bio-nanocomposites showed Au-protein core-shell structure and uniform distribution, and their sizes were dependent on the additive amount of HAuCl 4 . Interestingly, Au@BSA NPs showed remarkable catalytic activity for the reduction of 4-NP into 4-aminophenol in the presence of sodium borohydride. Due to the introduction of Au@BSA NPs, the reduction reaction could be conducted at ambient temperature and pressure without any additional conditions. Moreover, the reduction rate was closely related to the sizes of NPs and reaction temperature, and the catalytic mechanism was verified to follow the pseudo-first-order kinetics. Due to the environmentally friendly synthesis process and green reduction strategy of 4-NP, Au@BSA NPs would show great potential in governance of the biotoxin in medicine. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Preparation and characterization of the conjugated Fusarium mycotoxins zearalenone-4O-beta-D-glucopyranoside, alpha-zearalenol-4O-beta-D-glucopyranoside and beta-zearalenol-4O-beta-D-glucopyranoside by MS/MS and two-dimensional NMR.

    Science.gov (United States)

    Berthiller, F; Hametner, C; Krenn, P; Schweiger, W; Ludwig, R; Adam, G; Krska, R; Schuhmacher, R

    2009-02-01

    Glucosides of several Fusarium mycotoxins occur in naturally infected cereals and may contribute to an increased content to the total mycotoxin load of food and feed. The paper presents the results of a fermentation procedure to produce zearalenone-4O-beta-D-glucopyranoside from zearalenone using an engineered Saccharomyces cerevisiae strain, expressing the Arabidopsis thaliana UDP-glucosyltransferase UGT73C6. About 24 mg of zearalenone-4O-beta-D-glucopyranoside was obtained from 50 mg of zearalenone and further purified. A total of 10 mg of the glucoside were reduced with sodium borohydride, yielding 4.1 mg alpha-zearalenol-4O-beta-D-glucopyranoside and 4.5 mg beta-zearalenol-4O-beta-D-glucopyranoside at purities higher than 99%. To confirm the identities of the three produced glucosides, MS and MS/MS spectra were acquired using negative electrospray ionization. Besides the deprotonated ions at m/z 479 or 481, respectively, in full-scan mode, fragments, adducts, and dimers were recorded and assigned. MS/MS spectra of the glucosylated substances yielded the deprotonated ions of the mycotoxins zearalenone, alpha-zearalenol, beta-zearalenol and their fragments, respectively. Unambiguous structural assignment of the three substances was achieved using two-dimensional NMR methods. This way, the glucose attachment to position C-4, the beta-configuration of the sugar unit and the stereo-chemical assignment of the zearalenol hydroxyl group at C-6' were proven.

  4. Production of zearalenone-4-glucoside, a-zearalenol-4-glucoside and ß-zearalenol-4-glucoside.

    Science.gov (United States)

    Krenn, P; Berthiller, F; Schweiger, W; Hametner, C; Ludwig, R; Adam, G; Krska, R; Schuhmacher, R

    2007-12-01

    The work at hand describes the production of the zearalenone (ZON) metabolites zearalenone-4-glucoside (ZON-4G), a-zearalenol-4-glucoside (oc-ZOL-4G) and ß-zearalenol-4-glucoside (ß-ZOL-4G). In a first step a genetically modified yeast strain, expressing theArabidopsis thaliana UDP-glu-cosyltransferase UGT73C6, was treated with ZON to produce ZON-4G. The substance was purified by solid phase extraction and subsequent reversed phase preparative HPLC prior to the reduction with sodium borohydride to yield 0C-ZOL-4G and ß-ZOL-4G. The identity and purity of the substances were confirmed by(13)C-and(1)H-NMR as well as by HPLC-UV. In total, 50 mg of ZON were used to produce 5 mg of a-ZOL-4G with a purity of 98%, 6 mg of ß-ZOL-4G with a purity of 99% and 5 mg of ZON-4G with a purity of 99%.

  5. A new route for synthesis of silver:gold alloy nanoparticles loaded within phosphatidylcholine liposome structure as an effective antibacterial agent against Pseudomonas aeruginosa.

    Science.gov (United States)

    Salehi, Amir H; Montazer, Majid; Toliyat, Tayebeh; Mahmoudi-Rad, Mahnaz

    2015-03-01

    Ag:Au alloy nanoparticles were successfully synthesized through the new route using co-reduction method with silver nitrate, chloroauric acid, cetyl trimethyl ammonium bromide (CTAB) and sodium borohydride at room temperature. The Ag:Au alloy nanoparticles were then loaded within the phosphatidylcholine (97%) liposome structure. Various molar ratios of phosphotidylcholine and CTAB to the total metals were investigated showing its importance on the stability of nanocomposites suspension. The size distribution and morphology of encapsulated nanoparticles within the liposome structure were studied via ultraviolet (UV)-visible spectrum, transmission electron microscope (TEM) micrographs, and dynamic light scattering data. The synthesis of alloy nanoparticles were confirmed with formation of single band at 430, 465 and 500 nm for 75:25, 50:50 and 25:75 Ag:Au mole ratios, respectively. The TEM micrographs of different samples indicated formation of three various nanocomposite structures with size of 82-300 nm. The antibacterial activities of Ag:Au nanocomposites were studied against Pseudomonas aeruginosa through well-diffusion agar. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by Broth microdilution method. The results showed that 10 ppm nanocomposite reasonably killed the above bacteria.

  6. In-situ reduced silver nanoparticles on populus fiber and the catalytic application

    Energy Technology Data Exchange (ETDEWEB)

    Li, Miaomiao; Gong, Yumei, E-mail: ymgong@dlpu.edu.cn; Wang, Wenheng; Xu, Guangpeng; Liu, Yuanfa; Guo, Jing, E-mail: guojing8161@163.com

    2017-02-01

    Highlights: • A composite involved in in-situ chelating AgNPs on natural cellulose was prepared. • Polyamidoxime grafted from the cellulose adsorbed Ag+ which was reduced to AgNPs. • The composite exhibits excellent catalytic activity in reducing 4-nitrophenol. - Abstract: One kind of composites involved in silver nanoparticles (AgNPs) loading in-situ on natural populus fiber (PF) matrix was prepared by polyamidoxime (PAO) functionalized the cellulose fiber. In which PAO worked as trapping and stabilizing agents chelating silver ions and made it reduced in-situ to obtain AgNPs by borohydride at room temperature. The synthesized composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Moreover, the composites showed significant catalytic activity 1.87 s{sup −1} g{sup −1} and repeated usability more than 7 cycles in reducing 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) detected by UV–vis spectrophotometer in aqueous solution due to the surface-enhanced immobility and large amount of AgNPs. The natural cellulose fiber provides a green platform to react and support other noble metals for wide catalytic reactions.

  7. 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}.

  8. Synthesis and Heme Polymerization Inhibitory Activity (HPIA Assay of Antiplasmodium of (1-N-(3,4-Dimethoxybenzyl-1,10-Phenanthrolinium Bromide from Vanillin

    Directory of Open Access Journals (Sweden)

    Dhina Fitriastuti

    2014-03-01

    Full Text Available The synthesis of (1-N-(3,4-dimethoxy-benzyl-1,10-phenanthrolinium bromide had been conducted from vanillin. Heme polymerization inhibitory activity assay of the synthesized antiplasmodium has also been carried out. The first step of reaction was methylation of vanillin using dimethylsulfate and NaOH. The mixture was refluxed for 2 h to yield veratraldehyde in the form of light yellow solid (79% yield. Methylation product was reduced using sodium borohydride (NaBH4 with grinding method and yielded veratryl alcohol in the form of yellow liquid (98% yield. Veratryl alcohol was brominated using PBr3 to yield yellowish black liquid (85% yield. The final step was benzylation of 1,10-phenanthroline monohydrate with the synthesized veratryl bromide under reflux condition in acetone for 14 h to afford (1-N-(3,4-dimethoxy-benzyl-1,10-phenanthrolinium bromide (84% as yellow solid with melting point of 166-177 °C. The structures of products were characterized by FT-IR, GC-MS and 1H-NMR spectrometers. The results of heme polymerization inhibitory activity assay of (1-N-(3,4-dimethoxybenzyl-1,10-phenanthrolinium bromide showed that it had IC50 HPIA of 3.63 mM, while chloroquine had IC50 of4.37 mM. These results indicated that (1-N-(3,4-dimethoxybenzyl-1,10-phenanthrolinium bromide was more potential antiplasmodium than chloroquine.

  9. Thematic outlook: the technical outlook for the fuel cell research network (PACO). September 23, 2003 update no. 16; Veille thematique. La veille technique pour le reseau PACO. Actualisation du 23 septembre 2003, no. 16

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    Summaries of several recent articles and patents are gathered here. They deal with fuel cells and hydrogen production and storage. Their different titles are given below: 1)the behaviour of the electrode potential in direct hydrazine fuels 2)a device of desalination fed with a fuel cell 3)experiment in the field of residential fuel cell systems at ECN (Energy Research Center) 4)'design of a divided feeding' for SOFC with an internal reforming system 5)water management and thermal management in a fuel cell vehicle fed with hydrogen extracted from sodium borohydride (NaBH{sub 4}) 6)a mathematical model of propulsion systems by PEMFC for mobile applications 7)assessment of the feasibility of a DMFC containing an alkaline membrane 8)semi-empirical assessment model of the performance of a DMFC, first part: development of the model and validation 9)PEMFC and the challenge of CO 10)materials for SOFC 11)natural gas and LPG desulfurization for fuel cells reformers 12)heat exchangers for reforming techniques 13)desulfurization of a fuel for fuel cell system 14)hydrogen production from solar thermal reactor 15)hydrogen physico-chemical storage: nano-structured storage materials having modified covalent bonds sp2. The references of these articles and patents are detailed. (O.M.)

  10. Method and apparatus for separating uranium isotopes

    International Nuclear Information System (INIS)

    Bernstein, E.R.

    1977-01-01

    A uranium compound in the solid phase (uranium borohydride four) is subjected to radiation of a first predetermined frequency that excites the uranium-235 isotope-bearing molecules but not the uranium-238 isotope-bearing molecules. The compound is simultaneously subjected to radiation of a second predetermined frequency which causes the excited uranium-235 isotope-bearing molecules to chemically decompose but which does not affect the uranium-238 isotope-bearing molecules. Sufficient heat is then applied to the irradiated compound in the solid phase to vaporize the non-decomposed uranium-238 isotope-bearing molecules but not the decomposed uranium-235 isotope-bearing molecules, thereby physically separating the uranium-235 isotope-bearing molecules from the uranium-238 isotope-bearing molecules. The uranium compound sample in the solid phase is deposited or grown in an elongated tube supported within a dewar vessel having a clear optical path tail section surrounded by a coolant. Two sources of radiation are focused on the uranium compound sample. A heating element is attached to the elongated tube to vaporize the irradiated compound

  11. Analysis of the decomposition gases from {alpha} and {beta}-Cd(BH{sub 4}){sub 2} synthesized by temperature controlled mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, D., E-mail: dibl@dtu.dk [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399 Building 238, DK-4000 Roskilde (Denmark); Zatti, M.; Vegge, T. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399 Building 238, DK-4000 Roskilde (Denmark)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Temperature controlled metathesis reaction of LiBH{sub 4} with CdCl{sub 2}. Black-Right-Pointing-Pointer Temperature controlled mechanical synthesis of alpha and beta Cd(BH{sub 4}){sub 2}. Black-Right-Pointing-Pointer Semi-quantitative analysis of the decomposition gases, 1:1 H{sub 2} + B{sub 2}H{sub 6}, released by Cd(BH{sub 4}){sub 2}. - Abstract: We present a comprehensive study on the controlled phase synthesis and thermal decomposition of Cd(BH{sub 2}){sub 4}, a material for solid state hydrogen storage obtained via the metathesis reaction of LiBH{sub 4} with CdCl{sub 2}. By adjusting the stochiometry of the reactants and controlling the mechanical milling vial temperature, we have isolated the tetragonal (P4{sub 2}mn) low temperature phase and the cubic (Pn3{sup Macron }m) high temperature phase of the cadmium borohydride. Cd(BH{sub 2}){sub 4} has a low thermodynamic stability and decomposes with fast kinetic at 348 K, when heated at 1 K min{sup -1} against a backpressure of 1 bar H{sub 2}. A semi-quantitative analysis reveals that the decomposition gases are composed of 1:1 H{sub 2} + B{sub 2}H{sub 6} and that only Cd remains as solid crystalline phase.

  12. Combined bactericidal activity of silver nanoparticles and hexadecylpyridinium salicylate ionic liquid

    Science.gov (United States)

    Silveira, Leonardo T.; Liberatore, Ana Maria A.; Koh, Ivan H. J.; Bizeto, Marcos A.; Camilo, Fernanda F.

    2015-03-01

    Recently, ionic liquids have been used as dispersing agents for silver nanoparticle (AgNP) preparation. In this paper, we have shown a simple method to prepare AgNP in aqueous media using an ionic liquid called hexadecylpyridinium salicylate (HDPSal) as dispersing agent. The dispersions were produced by the chemical reduction of silver ions in aqueous media with different concentrations of HDPSal and tetrabutylammonium borohydride as reducing agent. The UV-Visible electronic spectra showed the characteristic plasmonic resonance band around 420 nm, confirming the formation of AgNPs. The TEM images confirmed the formation of spherical particles with diameters lower than 10 nm. The charge of these particles was determined by Zeta potential and they were around +50 mV, indicating that the HDP cations are surrounding the AgNPs, avoiding their agglomeration. Most of the dispersions remained stable for at least 1 month. Microbiological assays showed that the combination of AgNP with HDPSal results in wider range of antimicrobial effect.

  13. Mass-produced multi-walled carbon nanotubes as catalyst supports for direct methanol fuel cells.

    Science.gov (United States)

    Jang, In Young; Park, Ki Chul; Jung, Yong Chae; Lee, Sun Hyung; Song, Sung Moo; Muramatsu, Hiroyuki; Kim, Yong Jung; Endo, Morinobu

    2011-01-01

    Commercially mass-produced multi-walled carbon nanotubes, i.e., VGNF (Showa Denko Co.), were applied to support materials for platinum-ruthenium (PtRu) nanoparticles as anode catalysts for direct methanol fuel cells. The original VGNFs are composed of high-crystalline graphitic shells, which hinder the favorable surface deposition of the PtRu nanoparticles that are formed via borohydride reduction. The chemical treatment of VGNFs with potassium hydroxide (KOH), however, enables highly dispersed and dense deposition of PtRu nanoparticles on the VGNF surface. This capability becomes more remarkable depending on the KOH amount. The electrochemical evaluation of the PtRu-deposited VGNF catalysts showed enhanced active surface areas and methanol oxidation, due to the high dispersion and dense deposition of the PtRu nanoparticles. The improvement of the surface deposition states of the PtRu nanoparticles was significantly due to the high surface area and mesorporous surface structure of the KOH-activated VGNFs.

  14. 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

    2014-09-09

    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.

  15. Synthesis of self-assembly plasmonic silver nanoparticles with tunable luminescence color

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ghamdi, Haifa S.; Mahmoud, Waleed E., E-mail: w_e_mahmoud@yahoo.com

    2014-01-15

    Assembly is an elegant and effective bottom-up approach to prepare arrays of nanoparticles from nobel metals. Noble metal nanoparticles are perfect building blocks because they can be prepared with an adequate functionalization to allow their assembly and with controlled sizes. Herein, we report a novel recipe for the synthesis of self-assembled silver nanoparticles with tunable optical properties and sizes. The synthetic route followed here based on the covalent binding among silver nanoparticles by means of poly vinyl alcohol for the first time. The size of silver nanoparticle is governed by varying the amount of sodium borohydride. The as-synthesized nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, energy dispersive x-ray spectroscopy, selected area electron diffraction and UV–vis spectroscopy. Results depicted that self-assembly of mono-dispersed silver nanoparticles with different sizes have been achieved. The silver nanostructure has a single crystalline faced centered cubic structure with growth orientation along (1 1 1) facet. These nanoparticles exhibited localized surface plasmon resonance at 403 nm. The luminescence peaks were red-sifted from violet to green due to the increase of the particle sizes. -- Highlights: • Self-assembled silver nanoparticles based PVA were synthesized. • NaBH{sub 4} amount was found particle size dependent. • Silver nanoparticles strongly affected the surface plasmon resonance. • Highly symmetric luminescence emission band narrow width is obtained. • Dark field image showed a tunable color change from violet to green.

  16. Bactericidal and catalytic performance of green nanocomposite based-on chitosan/carbon black fiber supported monometallic and bimetallic nanoparticles.

    Science.gov (United States)

    Ali, Fayaz; Khan, Sher Bahadar; Kamal, Tahseen; Anwar, Yasir; Alamry, Khalid A; Asiri, Abdullah M

    2017-12-01

    Nanoparticles were synthesized on the surface of green nanocomposite based on carbon black dispersed in chitosan (CB-CS) fibres. The nanoparticles were monometallic Co, Ag and Cu and bimetallic Co + Cu and Co + Ag. The CB-CS fibres were prepared and introduced into separate metal salt solutions containing Co 2+ , Ag + and Cu 2+ and mixed Co 2+ +Cu 2+ and Co 2+ +Ag + ions. The metal ions immobilized on the surface of CB-CS were reduced using sodium borohydride (NaBH 4 ) as reducing agent to synthesize the corresponding zero-valent metal nanoparticles-loaded CB-CS fibres. All the nanoparticles-loaded CB-CS samples were characterized using field emission-scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. When tested as catalysts, the nanoparticles-loaded CB-CS showed excellent catalytic ability for the reduction of toxic and environmentally unwanted pollutants of para-nitrophenol, congo red and methyl orange dyes. Afterwards, the antimicrobial activities of virgin and metal-loaded CB-CS fibres were tested and the metal-loaded CB-CS fibres were found to be effective against Escherichia coli. In addition, the catalyst can be recovered easily by simply removing the fibres from the reaction mixture and can be recycled several times while maintaining high catalytic efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. 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.

  18. A Simple Assay for Ultrasensitive Colorimetric Detection of Ag+ at Picomolar Levels Using Platinum Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yi-Wei Wang

    2017-11-01

    Full Text Available In this work, uniformly-dispersed platinum nanoparticles (PtNPs were synthesized by a simple chemical reduction method, in which citric acid and sodium borohydride acted as a stabilizer and reducer, respectively. An ultrasensitive colorimetric sensor for the facile and rapid detection of Ag+ ions was constructed based on the peroxidase mimetic activities of the obtained PtNPs, which can catalyze the oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB by H2O2 to produce colored products. The introduced Ag+ would be reduced to Ag0 by the capped citric acid, and the deposition of Ag0 on the PtNPs surface, can effectively inhibit the peroxidase-mimetic activity of PtNPs. Through measuring the maximum absorption signal of oxidized TMB at 652 nm, ultra-low detection limits (7.8 pM of Ag+ can be reached. In addition to such high sensitivity, the colorimetric assay also displays excellent selectivity for other ions of interest and shows great potential for the detection of Ag+ in real water samples.

  19. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Amorphous boron-doped sodium titanates hydrates: Efficient and reusable adsorbents for the removal of Pb2+from water.

    Science.gov (United States)

    di Bitonto, Luigi; Volpe, Angela; Pagano, Michele; Bagnuolo, Giuseppe; Mascolo, Giuseppe; La Parola, Valeria; Di Leo, Paola; Pastore, Carlo

    2017-02-15

    Amorphous titanium hydroxide and boron-doped (B-doped) sodium titanates hydrates were synthetized and used as adsorbents for the removal of Pb 2+ from water. The use of sodium borohydride (NaBH 4 ) and titanium(IV) isopropoxide (TTIP) as precursors permits a very easy synthesis of B-doped adsorbents at 298K. The new adsorbent materials were first chemically characterized (XRD, XPS, SEM, DRIFT and elemental analysis) and then tested in Pb 2+ adsorption batch experiments, in order to define kinetics and equilibrium studies. The nature of interaction between such sorbent materials and Pb 2+ was also well defined: besides a pure adsorption due to hydroxyl interaction functionalities, there is also an ionic exchange between Pb 2+ and sodium ions even working at pH 4.4. Langmuir model presented the best fitting with a maximum adsorption capacity up to 385mg/g. The effect of solution pH and common ions (i.e. Na + , Ca 2+ and Mg 2+ ) onto Pb 2+ sorption were also investigated. Finally, recovery was positively conducted using EDTA. Very efficient adsorption (>99.9%) was verified even using tap water spiked with traces of Pb 2+ (50ppb). Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Hydrogen storage performance of functionalized hexagonal boron nitride for fuel cell applications

    Science.gov (United States)

    Muthu, R. Naresh; Rajashabala, S.; Kannan, R.

    2017-05-01

    Developing light weight, safe, efficient and compact hydrogen storage medium are still the major concerns for the blooming of hydrogen based energy economy. In the present article, activated hexagonal boron nitride (ABN) and ABN functionalized with lithium borohydride (ABN-LiBH4) nanocomposite based hydrogen storage medium are synthesized. where a facile solvent-assistant technique was adopted for the preparation of ABN-LiBH4 nanocomposite. The prepared hydrogen storage medium was subjected to various characterization techniques such as XRD, FTIR, SEM, EDX, CHNS - elemental analysis and TGA. Sievert's-like hydrogenation setup has been utilized for hydrogenation studies. It is noticed that the ABN-LiBH4 nanocomposite exhibits an attractive high gravimetric density of 1.67 wt% at 100 °C than pristine ABN. Moreover the stored hydrogen is released in the temperature range of 115 - 150 °C and possesses an average binding energy of 0.31 eV. These results indicate that the prepared ABN-LiBH4 nanocomposite paves a way to potential solid state hydrogen storage medium towards fuel cell technology as per the targets set by US Department of Energy (DOE).

  2. Liquid Marbles Stabilized by Fluorine-Bearing Cyclomatrix Polyphosphazene Particles and Their Application as High-Efficiency Miniature Reactors.

    Science.gov (United States)

    Wei, Wei; Lu, Rongjie; Ye, Weitao; Sun, Jianhua; Zhu, Ye; Luo, Jing; Liu, Xiaoya

    2016-02-23

    Increasing attention has been paid to fabricate multifunctional stabilizers of liquid marbles for expanding their application. Here, a kind of hydrophobic cyclomatrix polyphosphazene particles (PZAF) were facilely prepared using a one-step precipitation polycondensation of hexachlorocyclotriphosphazene and 4,4'-(hexafluoroisopropylidene)diphenol, and their ability to stabilize liquid marbles was first investigated. The Ag nanoparticle-decorated PZAF particles (Ag/PZAF) were then fabricated by an in situ reduction of silver nitrate onto PZAF particles and used to construct catalytic liquid marbles. The results revealed that the reduction of methylene blue (MB) in aqueous solution by sodium borohydride could be highly efficiently catalyzed in the catalytic liquid marbles, even with a large volume. An excellent cycle use performance of the catalytic liquid marbles without losing catalytic efficiency was also present. The high catalytic activity is mainly attributed to the uniform immobilization of Ag nanoparticles onto PZAF particles and the adsorption behavior of PZAF particles toward MB, which may play an effect on allowing high catalytic surface area and effective accelerating the mass transfer of MB to the Ag catalytic active sites, respectively. Therefore, the combination of Ag nanoparticles with PZAF particles has been demonstrated clearly to be a facile and effective strategy to obtain the functional stabilizer for preparing the catalytic liquid marbles as promising miniature reactors used in heterogeneous catalytic reactions.

  3. Graphite-supported 2,2′-bipyridine-capped ultrafine tin nanoparticles for anodes of lithium-ion batteries

    International Nuclear Information System (INIS)

    Nabais, Catarina; Schneider, Raphaël; Willmann, Patrick; Billaud, Denis

    2012-01-01

    Highlights: ► 2,2′-bipyridine capped Sn nanoparticles as anode materials for Li-ion batteries. ► High dispersion of Sn nanoparticles at the surface of the graphite matrix. ► The introduction of 2,2′-bipyridine improves the capacity and cycling stability. ► A stable reversible capacity of ca. 480 mA h g −1 after 20 cycles was observed. - Abstract: Monodisperse and small tin nanoparticles were prepared from a 2,2′-bipyridine–tin(+2) chloride complex using sodium borohydride as reducing agent. When the synthesis was conducted in the presence of graphite, Sn particles with an average diameter of ca. 29 nm well-dispersed at the surface of graphite were obtained. Electrochemical lithium insertion was carried out in these materials. A stable reversible capacity of ca. 480 mA h g −1 , value 37% higher than that of pure graphite, was found.

  4. Zirconia coating for enhanced thermal stability of gold nanoparticles

    Science.gov (United States)

    Pastre, A.; Cristini-Robbe, O.; Bois, L.; Chassagneux, F.; Branzea, D.; Boé, A.; Kinowski, C.; Raulin, K.; Rolland, N.; Bernard, R.

    2016-01-01

    This paper describes a rapid, simple and one-step method for the preparation of 2-4 nm diameter zirconia-coated gold nanoparticles at room temperature. These nanoparticles were synthesized by two simultaneous processes: the chemical reduction of tetrachloroauric acid with sodium borohydride and the formation of zirconia sol-gel matrices. All the gold nanoparticle sols were characterized by UV-visible absorption and transmission electron microscopy to determine the nanoparticle size and shape. The synthesis method is a combination of a polymeric structure of the amorphous zirconia and the use of a strong reducing agent, and it yields to very small quasi-spherical gold nanoparticles at room temperature. The thermal stability up to 1200 °C of the coated nanoparticles was studied by x-ray diffraction. The metastable tetragonal phase of the zirconia coating was obtained at 400 °C, and a progressive transformation from tetragonal to monoclinic phases of the zirconia coating was observed up to 1100 °C. After the heat treatment at 400 °C, the crystallite size of the gold nanoparticles was about 29 nm, and it remained unchanged from 400 °C to 1200 °C. These results are promising for the development of such materials as doping elements for optical fiber applications.

  5. Synthesis of amorphous Mg(BH{sub 4}){sub 2} from MgB{sub 2} and H{sub 2} at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Pistidda, Claudio [Karlsruhe Institute of Technology, Institute of Nanotechnology, Postfach 3640, 76021 Karlsruhe (Germany); Garroni, Sebastiano [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Dolci, Francesco; Bardaji, Elisa Gil [Karlsruhe Institute of Technology, Institute of Nanotechnology, Postfach 3640, 76021 Karlsruhe (Germany); Khandelwal, Ashish [Dipartimento di Ingegneria Meccanica, Settore Materiali and CNISM, Universita di Padova, Via Marzolo 9, 35131 Padova (Italy); Nolis, Pau [Servei de Ressonancia Magnetica Nuclear (SeRMN), Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Dornheim, Martin; Gosalawit, Rapee [Institute of Materials Research, Materials Technology, GKSS Research Centre Geesthacht GmbH, Max-Planck-Strasse 1, D-21502 Geesthacht (Germany); Jensen, Torben [Interdisciplinary Nanoscience Centre (iNANO) and Department of Chemistry, University of Aarhus, Langelandsgabe 140, DK-8000 (Denmark); Cerenius, Yngve [MAX-lab, Lund University, S-22100 Lund (Sweden); Surinach, Santiago; Baro, Maria Dolors [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Lohstroh, Wiebke [Karlsruhe Institute of Technology, Institute of Nanotechnology, Postfach 3640, 76021 Karlsruhe (Germany); Fichtner, Maximilian, E-mail: m.fichtner@kit.ed [Karlsruhe Institute of Technology, Institute of Nanotechnology, Postfach 3640, 76021 Karlsruhe (Germany)

    2010-10-15

    Graphical abstract: Display Omitted Research highlights: {yields} Amorphous Mg(BH{sub 4}){sub 2} can be synthesized from MgB{sub 2} in a solvent-free route. {yields} Synthesis is performed room temperature by ball milling MgB{sub 2} under hydrogen pressure. {yields} The material is X-ray amorphous but shows characteristic near order and decomposition products. - Abstract: Due to its high hydrogen content and its favourable overall thermodynamics magnesium tetrahydroborate has been considered interesting for hydrogen storage applications. In this work we show that unsolvated amorphous magnesium tetrahydroborate can be obtained by reactive ball milling of commercial MgB{sub 2} under 100 bar hydrogen atmosphere. The material was characterized by solid-state NMR which showed the characteristic features of Mg(BH{sub 4}){sub 2}, together with those of higher borohydride species. High pressure DSC and TPD-MS showed thermal behaviour similar to that of Mg(BH{sub 4}){sub 2} but with broadened signals. In situ synchrotron X-ray powder diffraction confirmed the amorphous state of the material and showed the typical crystalline decomposition products of Mg(BH{sub 4}){sub 2} at elevated temperatures.

  6. Magneto-plasmonic Au-Coated Co nanoparticles synthesized via hot-injection method

    Science.gov (United States)

    Souza, João B., Jr.; Varanda, Laudemir C.

    2018-02-01

    A synthetic procedure is described for the obtaining of superparamagnetic Co nanoparticles (NPs) via hot-injection method in the presence of sodium borohydride. The Co NPs obtained have an average diameter of 5.3 nm and saturation magnetization of 115 emu g‑1. A modified Langevin equation is fitted to the magnetization curves using a log-normal distribution for the particle diameter and an effective field to account for dipolar interactions. The calculated magnetic diameter of the Co NPs is 0.6 nm smaller than TEM-derived values, implying a magnetic dead layer of 0.3 nm. The magnetic core is coated with Au to prevent oxidation, resulting in water-stable magneto-plasmonic Co/Au core/shell NPs with saturation of 71.6 emu g‑1. The coating adds a localized surface plasmon resonance property with absorbance in the so-called ‘therapeutic window’ (690–900 nm), suitable for biomedical applications. It is suggested that these multifunctional NPs are distinguished as a potential platform for applied and fundamental research.

  7. Use of PtAu/C electrocatalysts toward formate oxidation: electrochemical and fuel cell considerations

    Directory of Open Access Journals (Sweden)

    Sirlane G. da Silva

    2016-09-01

    Full Text Available Abstract This study reports the use of PtAu/C electrocatalysts with different atomic ratios (90:10, 70:30 and 50:50 supported on Vulcan XC 72 carbon and prepared by the sodium borohydride method toward formate electro-oxidation in alkaline media. The materials were characterized by X-ray diffraction, showing peaks characteristics of Pt and Au face-centered-cubic structures, and also by transmission electron micrographs that show the nanoparticles well dispersed on carbon and a mean particle size between 4 and 5 nm for all electrocatalysts. Electrochemical experiments show PtAu/C as promising catalysts toward formate oxidation, while single cell experiments reveal PtAu/C 90:10 as the best material since it provides a power density higher than Pt/C. The incorporation of Au could increase formate oxidation for more than one reason: (i a facilitated rupture of C–H bond; (ii the Au/oxide interface or (iii by regenerating active sites.

  8. 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.

  9. Antibacterial continuous nanofibrous hybrid yarn through in situ synthesis of silver nanoparticles: Preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Barani, Hossein, E-mail: barani@birjand.ac.ir

    2014-10-01

    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.

  10. Tailoring Cu Nanoparticle Catalyst for Methanol Synthesis Using the Spinning Disk Reactor

    Directory of Open Access Journals (Sweden)

    Christian Ahoba-Sam

    2018-01-01

    Full Text Available Cu nanoparticles are known to be very active for methanol (MeOH synthesis at relatively low temperatures, such that smaller particle sizes yield better MeOH productivity. We aimed to control Cu nanoparticle (NP size and size distribution for catalysing MeOH synthesis, by using the spinning disk reactor. The spinning disk reactor (SDR, which operates based on shear effect and plug flow in thin films, can be used to rapidly micro-mix reactants in order to control nucleation and particle growth for uniform particle size distribution. This could be achieved by varying both physical and chemical operation conditions in a precipitation reaction on the SDR. We have used the SDR for a Cu borohydride reduction to vary Cu NP size from 3 nm to about 55 nm. XRD and TEM characterization confirmed the presence of Cu2O and Cu crystallites when the samples were dried. This technique is readily scalable for Cu NP production by processing continuously over a longer duration than the small-scale tests. However, separation of the nanoparticles from solution posed a challenge as the suspension hardly settled. The Cu NPs produced were tested to be active catalyst for MeOH synthesis at low temperature and MeOH productivity increased with decreasing particle size.

  11. HyMARC (Sandia) Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Stavila, Vitalie [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Klebanoff, Leonard E. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Kolasinski, Robert [Sandia National Lab. (SNL-CA), Livermore, CA (United States); El Gabaly Marquez, Farid [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Zhou, Xiaowang [Sandia National Lab. (SNL-CA), Livermore, CA (United States); White, James Lawrence [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2017-07-01

    The Sandia HyMARC team continued its development of new synthetic, modeling, and diagnostic tools that are providing new insights into all major classes of storage materials, ranging from relatively simple systems such as PdHx and MgH2, to exceptionally complex ones, such as the metal borohydrides, as well as materials thought to be very well-understood, such as Ti-doped NaAlH4. This unprecedented suite of capabilities, capable of probing all relevant length scales within storage materials, is already having a significant impact, as they are now being used by both Seedling projects and collaborators at other laboratories within HyMARC. We expect this impact to grow as new Seedling projects begin and through collaborations with other scientists outside HyMARC. In the coming year, Sandia efforts will focus on the highest impact problems, in coordination with the other HyMARC National Laboratory partners, to provide the foundational science necessary to accelerate the discovery of new hydrogen storage materials.

  12. Enhanced Congo red dye removal from aqueous solutions using iron nanoparticles: adsorption, kinetics, and equilibrium studies.

    Science.gov (United States)

    Kim, Se-Ho; Choi, Pyuck-Pa

    2017-11-14

    We report on the Congo red dye removal properties of body centred cubic and amorphous iron nanoparticles, synthesized by a facile borohydride reduction method under ambient conditions. We have analyzed the adsorption of Congo red as a function of dye concentration, time, and temperature and measured a Congo red adsorption capacity of 1735 mg g -1 for the amorphous iron nanoparticles. To our knowledge, this is the highest value reported so far for Congo red adsorption. The acquired data have been evaluated applying various models for adsorption kinetics and thermodynamic studies. The isotherm models as well as acquired Fourier transform infrared spectra suggest that both chemi- and physisorption occur for Congo red adsorption on iron nanoparticles, where chemisorption appears to be dominant. The kinetics of adsorption of Congo red on both bcc-structured and amorphous iron follow a pseudo-second order equation and are characterized by high initial adsorption rates. Diffusion studies indicate that adsorption occurs in two stages, namely film diffusion followed by intraparticle diffusion. Our studies show that amorphous iron nanoparticles are highly promising for dye adsorption and wastewater treatment applications.

  13. Preparation, characterization, and use of monoclonal antibodies to vitamin B6.

    Science.gov (United States)

    Viceps-Madore, D; Cidlowski, J A; Kittler, J M; Thanassi, J W

    1983-02-25

    Monoclonal antibodies exhibiting various specificities for B6 vitamer forms have been prepared. The antigen preparation employed was a partially purified mixture of human placental proteins that had been derivatized by reaction with pyridoxal 5'-phosphate and sodium borohydride. Spleen cells obtained from mice immunized with the phosphopyridoxyl protein preparation were fused with the mouse myeloma cell line designated X63-Ag8.653. The resulting hybridomas were screened for production of antibodies to the haptenic phosphopyridoxyl group using an enzyme-linked immunosorbent assay. Clones producing such antibodies were isolated by limiting dilution methods. The monoclonal antibodies obtained in this fashion have been characterized with respect to their ability to interact with various forms of vitamin B6. In addition, these antibodies have been shown to be useful in the detection of cellular pyridoxal phosphate binding components using immunoblot techniques. Monoclonal antibodies to vitamin B6 derivatives are potentially powerful tools in the assessment of vitamin B6 nutritional status and in the study of the roles of pyridoxal phosphate binding components in relation to growth, differentiation, carcinogenesis, and steroid hormone action.

  14. Effective reduction of p-nitrophenol by silver nanoparticle loaded on magnetic Fe3O4/ATO nano-composite

    Science.gov (United States)

    Karki, Hem Prakash; Ojha, Devi Prashad; Joshi, Mahesh Kumar; Kim, Han Joo

    2018-03-01

    A silver loaded hematite (Fe3O4) and antimony doped tin oxide (ATO) magnetic nano-composite (Ag-Fe3O4/ATO) was successfully synthesized by in situ one pot green and facile hydrothermal process. The formation of nano-composite, its structure, morphology, and stability were characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), electron diffraction spectroscopy (EDS), elemental mapping by high resolution scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR). UV-vis spectroscopy was used to monitor the catalytic reduction of p-nitrophenol (PNP) into p-aminophenol (PAP) in presence of Ag-Fe3O4/ATO nano-composite with excess of sodium borohydride (NaBH4). The pseudo-first order kinetic equation could describe the reduction of p-nitrophenol with excess of NaBH4. For the first time, ATO surface was used for hydrothermal growth of silver and iron oxide magnetic nanoparticles. The in situ growth of these nanoparticles provided an effective bonding of components of the nano-composite over the surface of ATO nanoparticles. This nano-composite exhibited easy synthesis, high stability, cost effective and rapid separation using external magnet. The excellent catalytic and anti-bacterial activity of as-synthesized silver nano-composite makes it potential nano-catalyst for waste water treatment as well as biomedical application.

  15. Combined bactericidal activity of silver nanoparticles and hexadecylpyridinium salicylate ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Leonardo T. [Universidade Federal de São Paulo, Laboratório de Materiais Híbridos, Departamento de Ciências Exatas e da Terra, Instituto de Ciências Ambientais, Químicas e Farmacêuticas (Brazil); Liberatore, Ana Maria A.; Koh, Ivan H. J. [Universidade Federal de São Paulo, Laboratório de Transplante Experimental de Órgãos, Departamento de Cirurgia, Escola Paulista de Medicina (Brazil); Bizeto, Marcos A.; Camilo, Fernanda F., E-mail: ffcamilo@unifesp.br [Universidade Federal de São Paulo, Laboratório de Materiais Híbridos, Departamento de Ciências Exatas e da Terra, Instituto de Ciências Ambientais, Químicas e Farmacêuticas (Brazil)

    2015-03-15

    Recently, ionic liquids have been used as dispersing agents for silver nanoparticle (AgNP) preparation. In this paper, we have shown a simple method to prepare AgNP in aqueous media using an ionic liquid called hexadecylpyridinium salicylate (HDPSal) as dispersing agent. The dispersions were produced by the chemical reduction of silver ions in aqueous media with different concentrations of HDPSal and tetrabutylammonium borohydride as reducing agent. The UV–Visible electronic spectra showed the characteristic plasmonic resonance band around 420 nm, confirming the formation of AgNPs. The TEM images confirmed the formation of spherical particles with diameters lower than 10 nm. The charge of these particles was determined by Zeta potential and they were around +50 mV, indicating that the HDP cations are surrounding the AgNPs, avoiding their agglomeration. Most of the dispersions remained stable for at least 1 month. Microbiological assays showed that the combination of AgNP with HDPSal results in wider range of antimicrobial effect.

  16. Silver nanoparticles: Influence of the temperature synthesis on the particles’ morphology

    International Nuclear Information System (INIS)

    Piñero, S; Camero, S; Blanco, S

    2017-01-01

    Silver nanoparticles have a wide range of applications in the medical field, textile and food industries. These and other applications can be found due to the relation between its size and morphology. In this study the influence of bath temperature on the morphology and size of silver nanoparticles are evaluated, which are obtained by chemical reduction of AgNO 3 using three reducing agents: sodium borohydride, ascorbic acid and sodium citrate. The evaluation carried out by the traditional UV-vis Spectrophotometric analysis and with High Resolution Transmission Electron Microscopy. The UV-vis spectrum of the silver colloids obtained by chemical reduction using three different reducing agents shows the effect of the temperature change on the growing and aggregative process. The final effect on the morphology, size and aggregation of the particles was confirmed by TEM. The result suggests a change in the growing mechanism, conducted by aggregation of atoms at 5 and 20°C degrees and aggregation of clusters at higher temperatures. Moreover in this work the main synthesis methods of nanomaterials are described. (paper)

  17. A DFT study of Cu nanoparticles adsorbed on defective graphene

    Energy Technology Data Exchange (ETDEWEB)

    García-Rodríguez, D.E. [Universidad Politécnica de Aguascalientes, Calle Paseo San Gerardo No. 297 Fracc. San Gerardo, 20342 Aguascalientes, Ags. (Mexico); Mendoza-Huizar, L.H. [Universidad Autónoma del Estado de Hidalgo, Área Académica de Química, Ciudad del Conocimiento. Carretera Pachuca-Tulancigo Km. 4.5 Mineral de la Reforma, 42186 Hidalgo (Mexico); Díaz, C., E-mail: cristina.diaz@uam.es [Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain); Institute for Advanced Research in Chemical Science (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2017-08-01

    Highlights: • Cu{sub n} supported on graphene may be a promising electrode material for DBFC's cells. • Cu{sub n}/graphene interaction is rather local and size independent. • Cu{sub 13} anchors strongly to defects in graphene, while keeping its gas-phase properties. - Abstract: Metal nanoparticles adsorbed on graphene are systems of interest for processes relative to catalytic reactions and alternative energy production. Graphene decorated with Cu-nanoparticles, in particular, could be a good alternative material for electrodes in direct borohydride fuel cells. However our knowledge of this system is still very limited. Based on density functional theory, we have analyzed the interaction of Cu{sub n} nanoparticles (n = 4, 5, 6, 7, 13) with pristine and defective-graphene. We have considered two types of defects, a single vacancy (SV), and an extended lineal structural defect (ELSD), formed by heptagon-pentagon pairs. Our analysis has revealed the covalent character of the Cu{sub n}-graphene interaction for pristine- and ELSD-graphene, and a more ionic-like interaction for SV-graphene. Furthermore, our analysis shows that the interaction between the nanoparticles and the graphene is rather local, i.e., only the nanoparticle atoms close to the contact region are involved in the interaction, being the electronic contact region much higher for defective-graphene than for pristine-graphene. Thus, the higher the particle the lower its average electronic and structural distortion.

  18. Charge density modification of carboxylated cellulose nanocrystals for stable silver nanoparticles suspension preparation

    International Nuclear Information System (INIS)

    Hoeng, Fanny; Denneulin, Aurore; Neuman, Charles; Bras, Julien

    2015-01-01

    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

  19. Influence of Ni doping on PtNi nanoparticles: Synthesis, electronic/atomic structure and photocatalyst investigations

    Science.gov (United States)

    Varshney, Mayora; Sharma, Aditya; Shin, Hyun-Joon; Lee, Hyun Hwi; Jeon, Tae-Yeol; Lee, Byeong-Hyeon; Chae, Keun-Hwa; Won, Sung Ok

    2017-11-01

    Carbon-supported Pt and PtNi nanoparticles (NPs) were synthesized using a borohydride reduction method. Structural properties were studied by synchrotron X-ray diffraction (XRD) and the size/shape of the NPs was determined by transmission electron microscope (TEM). X-ray absorption spectroscopy with its two amendments; X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), has been employed to investigate the local electronic/atomic structure surrounding the Pt and Ni atoms. XANES results, at Pt L3-edge and Ni K-edge, have shown fractional oxidation of Pt and Ni atoms. The Pt3Ni1NPs have exhibited a lower bond distance of Pt-Ni shell and higher coordination number of Pt-Ni shells, indicating the alloy formation between Pt and Ni. We further have demonstrated that the Pt and PtNi NPs can serve as effective photocatalysts towards the degradation of water pollutant dye (methyl orange (MO)). By considering the interband charge-transfer of Pt (5d →6sp), a tentative mechanism is proposed to understand the photocatalytic degradation of MO dye molecules by Pt/PtNi NPs under the light irradiation.

  20. 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.

  1. Effect of chemically reduced palladium supported catalyst on sunflower oil hydrogenation conversion and selectivity

    Directory of Open Access Journals (Sweden)

    Abdulmajid Alshaibani

    2017-02-01

    Full Text Available Catalytic hydrogenation of sunflower oil was studied in order to improve the conversion and to reduce the trans-isomerization selectivity. The hydrogenation was performed using Pd–B/γ-Al2O3 prepared catalyst and Pd/Al2O3 commercial catalyst under similar conditions. The Pd–B/γ-Al2O3 catalyst was prepared by wet impregnation and chemical reduction processes. It was characterized by Brunauer–Emmett–Teller surface area analysis (BET, X-ray powder diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The result of sunflower oil hydrogenation on Pd–B/γ-Al2O3 catalyst showed a 17% higher conversion and a 23% lower trans-isomerization selectivity compared to the commercial Pd/Al2O3 catalyst. The chemical reduction of palladium supported catalyst using potassium borohydride (KBH4 has affected the Pd–B/γ-Al2O3 catalyst’s structure and particle size. These most likely influenced its catalytic performance toward higher conversion and lower trans-isomerization selectivity.

  2. Atomic layer deposited cobalt oxide: An efficient catalyst for NaBH{sub 4} hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, Dip K.; Manna, Joydev; Dhara, Arpan; Sharma, Pratibha; Sarkar, Shaibal K., E-mail: shaibal.sarkar@iitb.ac.in [Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2016-01-15

    Thin films of cobalt oxide are deposited by atomic layer deposition using dicobalt octacarbonyl [Co{sub 2}(CO){sub 8}] and ozone (O{sub 3}) at 50 °C on microscope glass substrates and polished Si(111) wafers. Self-saturated growth mechanism is verified by x-ray reflectivity measurements. As-deposited films consist of both the crystalline phases; CoO and Co{sub 3}O{sub 4} that gets converted to pure cubic-Co{sub 3}O{sub 4} phase upon annealing at 500 °C under ambient condition. Elemental composition and uniformity of the films is examined by x-ray photoelectron spectroscopy and secondary ion-mass spectroscopy. Both as-deposited and the annealed films have been successfully tested as a catalyst for hydrogen evolution from sodium borohydride hydrolysis. The activation energy of the hydrolysis reaction in the presence of the as-grown catalyst is found to be ca. 38 kJ mol{sup −1}. Further implementation of multiwalled carbon nanotube, as a scaffold layer, improves the hydrogen generation rate by providing higher surface area of the deposited catalyst.

  3. Selective mass labeling for linking the optical properties of chromophoric dissolved organic matter to structure and composition via ultrahigh resolution electrospray ionization mass spectrometry.

    Science.gov (United States)

    Baluha, Daniel R; Blough, Neil V; Del Vecchio, Rossana

    2013-09-03

    The mass spectra acquired by ESI FT-ICR MS of untreated, borohydride-reduced, and borodeuteride-reduced samples of Suwannee River fulvic acid (SRFA) and a C18 extract from the upper Delaware Bay were compared to one another. Treatment of these samples with sodium borodeuteride was shown to produce unique mass labels for species which contain one or two ketone/aldehyde moieties. Approximately 30% of all identified peaks in the two samples were shown to comprise ketone/aldehyde-containing species. The molecular formulas of the majority of these species had O/C and H/C molar ratios typically attributed to lignin-derived compounds and/or carboxylic rich alicyclic molecules (CRAM). However, the significant loss of UV-vis absorption following reduction supports a lignin-based origin for the optical (and photochemical) properties of these samples. The mass-labeling method described and tested herein shows great promise as a means to further characterize the structure and composition of complex natural samples, especially in terms of identifying specific subsets of chemical species that contribute significantly to the optical and photochemical properties of such samples.

  4. Catalysis design for ring-opening polymerization of cyclic esters: 1. Group 1 metal and thallium(I) trispyrazolylborate complexes with hemilabile ligands.

    Science.gov (United States)

    Chisholm, Malcolm H; Gallucci, Judith C; Yaman, Gülsah

    2007-10-15

    The synthesis of 3-(2-methoxy-1,1-dimethylethyl)pyrazole, pz*H is described together with its reactions with the borohydrides MBH(4), where M = Li, Na, and K, under melt conditions. At 180 degrees C, this procedure leads to a mixture of products for M = Li, and at higher temperatures, a derivative LiTp'pz*H, 1, is isolated, wherein a B-H bond and a methyl group have been eliminated and a B-O bond has been formed. For M = Na, the reaction proceeds to give the tris-pyrazolylborate derivative NaTp*, 2, but at higher temperatures the tetra-pyrazolylborate complex NaB(pz*)(4), 3, is obtained. The reactions involving KBH4 and pz*H yield the dinuclear complex K(2)(Tp*)(2)pz*H, 4. The reaction between NaTp* and TlOAc in CH(2)Cl(2) at room temperature leads to the formation of TlTp*, 5, along with NaOAc. Thallium 5 reacts with methyllithium in diethylether to give LiTp*, 6, and thallium metal, and, similarly, 5 and KH react in tetrahydrofuran to give KTp*, 7 and Tl(0). 1-7 have been characterized by elemental analysis, NMR spectroscopy, and by single-crystal X-ray studies, the latter of which reveal the versatile modes of binding for this new ligand bearing hemilabile ether appendages.

  5. 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

  6. Enhanced Dissolution of Platinum Group Metals Using Electroless Iron Deposition Pretreatment

    Science.gov (United States)

    Taninouchi, Yu-ki; Okabe, Toru H.

    2017-12-01

    In order to develop a new method for efficiently recovering platinum group metals (PGMs) from catalyst scraps, the authors investigated an efficient dissolution process where the material was pretreated by electroless Fe deposition. When Rh-loaded alumina powder was kept in aqua regia at 313 K (40 °C) for 30 to 60 minutes, the Rh hardly dissolved. Meanwhile, after electroless Fe plating using a bath containing sodium borohydride and potassium sodium tartrate as the reducing and complexing agents, respectively, approximately 60 pct of Rh was extracted by aqua regia at 313 K (40 °C) after 30 minutes. Furthermore, when heat treatment was performed at 1200 K (927 °C) for 60 minutes in vacuum after electroless plating, the extraction of Rh approached 100 pct for the same leaching conditions. The authors also confirmed that the Fe deposition pretreatment enhanced the dissolution of Pt and Pd. These results indicate that an effective and environmentally friendly process for the separation and extraction of PGMs from catalyst scraps can be developed utilizing this Fe deposition pretreatment.

  7. Bimetallic Pt-Ru Nanoparticle Catalyst for Hydrogen Peroxide Detection

    Directory of Open Access Journals (Sweden)

    Metini Janyasupab

    2011-01-01

    Full Text Available A bimetallic Pt-Ru nanoparticle catalyst was prepared and characterized for the enhancement of hydrogen peroxide (H2O2 detection in biosensing applications. The particles were synthesized via sodium borohydride reduction, with low heat treatment, and characterized by TEM and HRTEM. The chemical composition analyses were performed by EDX. The bimetallic particle diameters ranged from 2 to 12 nm, with an average of 4.5 nm. The Pt-Ru catalyst exhibited an improved performance at low overpotential (+0.2 V versus Ag/AgCl reference electrode in H2O2 detection, suggesting a sensitivity value of 78.95 μA⋅mM-1 (or 402.1 μA⋅mM-1⋅cm-2 which was 30% higher than that for the single Pt catalyst. The major contribution of this enhancement comes from the stronger oxygen adsorption on Ru metal. The Pt-Ru catalyst also showed a more stable signal at the high overpotential (+0.4 V versus Ag/AgCl, providing better accuracy in the detection of H2O2.

  8. Potential drug – nanosensor conjugates: Raman, infrared absorption, surface – enhanced Raman, and density functional theory investigations of indolic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Pięta, Ewa, E-mail: Ewa.Pieta@ifj.edu.pl [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow (Poland); Paluszkiewicz, Czesława [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow (Poland); Oćwieja, Magdalena [J. Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, PL-30239 Krakow (Poland); Kwiatek, Wojciech M. [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow (Poland)

    2017-05-15

    Highlights: • Molecular fragments involved in the adsorption process were determined. • Formation of hydrogen bonds with the negatively charged gold substrates was observed. • Indole moiety strongly interacts with gold nanosensors. • The synthesized sensors are characterized by high stability and reproducibility. • Chemical mechanism plays a crucial role in the enhancement of the Raman signal. - Abstract: An extremely important aspect of planning cancer treatment is not only the drug efficiency but also a number of challenges associated with the side effects and control of this process. That is why it is worth paying attention to the promising potential of the gold nanoparticles combined with a compound treated as a potential drug. This work presents Raman (RS), infrared absorption (IR) and surface–enhanced Raman scattering (SERS) spectroscopic investigations of N–acetyl–5–methoxytryptamine (melatonin) and α–methyl–DL–tryptophan, regarding as anti breast cancer agents. The experimental spectroscopic analysis was supported by the quantum-chemical calculations based on the B3LYP hybrid density functional theory (DFT) at the B3LYP 6–311G(d,p) level of theory. The studied compounds were adsorbed onto two colloidal gold nanosensors synthesized by a chemical reduction method using sodium borohydride (SB) and trisodium citrate (TC), respectively. Its morphology characteristics were obtained using transmission electron microscopy (TEM). It has been suggested that the NH moiety from the aromatic ring, a well-known proton donor, causes the formation of hydrogen bonds with the negatively charged gold surface.

  9. Covalent binding of aniline to humic substances. 1. Kinetic studies

    Science.gov (United States)

    Weber, E.J.; Spidle, D.L.; Thorn, K.A.

    1996-01-01

    The reaction kinetics for the covalent binding of aniline with reconstituted IHSS humic and fulvic acids, unfractionated DOM isolated from Suwannee River water, and whole samples of Suwannee River water have been investigated. The reaction kinetics in each of these systems can be adequately described by a simple second-order rate expression. The effect of varying the initial concentration of aniline on reaction kinetics suggested that approximately 10% of the covalent binding sites associated with Suwannee River fulvic acid are highly reactive sites that are quickly saturated. Based on the kinetic parameters determined for the binding of aniline with the Suwannee River fulvic and humic acid isolates, it was estimated that 50% of the aniline concentration decrease in a Suwannee River water sample could be attributed to reaction with the fulvic and humic acid components of the whole water sample. Studies with Suwannee River fulvic acid demonstrated that the rate of binding decreased with decreasing pH, which parallels the decrease in the effective concentration of the neutral form, or reactive nucleophilic species of aniline. The covalent binding of aniline with Suwannee River fulvic acid was inhibited by prior treatment of the fulvic acid with hydrogen sulfide, sodium borohydride, or hydroxylamine. These observations are consistent with a reaction pathway involving nucleophilic addition of aniline to carbonyl moieties present in the fulvic acid.

  10. Micro space power system using MEMS fuel cell for nano-satellites

    Science.gov (United States)

    Lee, Jongkwang; Kim, Taegyu

    2014-08-01

    A micro space power system using micro fuel cell was developed for nano-satellites. The power system was fabricated using microelectromechanical system (MEMS) fabrication technologies. Polymer electrolyte membrane (PEM) fuel cell was selected in consideration of space environment. Sodium borohydride (NaBH4) was selected as a hydrogen source while hydrogen peroxide (H2O2) was selected as an oxygen source. The power system consists of a micro fuel cell, micro-reactor, micro-pump, and fuel cartridges. The micro fuel cell was fabricated on a light-weight and corrosion-resistant glass plates. The micro-reactor was used to generate hydrogen from NaBH4 alkaline solution via a catalytic hydrolysis reaction. All components such as micro-pump, fuel cartridges, and auxiliary battery were integrated for a complete power system. The storability of NaBH4 solution was evaluated at -25 °C and the performance of the micro power system was measured at various operating conditions. The power output of micro power system reasonably followed up the given electric load conditions.

  11. Versatile synthesis of PHMB-stabilized silver nanoparticles and their significant stimulating effect on fodder beet (Beta vulgaris L.).

    Science.gov (United States)

    Gusev, Alexander А; Kudrinsky, Alexey A; Zakharova, Olga V; Klimov, Alexey I; Zherebin, Pavel M; Lisichkin, George V; Vasyukova, Inna A; Denisov, Albert N; Krutyakov, Yurii A

    2016-05-01

    Silver nanoparticles (AgNPs) are well-known bactericidal agents. However, information about the influence of AgNPs on the morphometric parameters and biochemical status of most important agricultural crops is limited. The present study reports the influence of AgNPs stabilized with cationic polymer polyhexamethylene biguanide hydrochloride (PHMB) on growth, development, and biochemical status of fodder beet Beta vulgaris L. under laboratory and greenhouse conditions. PHMB-stabilized AgNPs were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The average diameter of thus prepared AgNPs was 10 nm. It appears that the results of experiments with laboratory-grown beets in the nanosilver-containing medium, where germination of seeds and growth of roots were suppressed, do not correlate with the results of greenhouse experiments. The observed growth-stimulating action of PHMB-stabilized AgNPs can be explained by the change of activity of oxidases and, consequently, by the change of auxins amount in plant tissues. In beets grown in the presence of PHMB-stabilized AgNPs no negative deviations of biological parameters from normal values were registered. Furthermore, the SEM/EDS examination revealed no presence of silver in the tissues of the studied plants. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Compact PEM fuel cell system combined with all-in-one hydrogen generator using chemical hydride as a hydrogen source

    International Nuclear Information System (INIS)

    Kim, Jincheol; Kim, Taegyu

    2015-01-01

    Highlights: • Compact fuel cell system was developed for a portable power generator. • Novel concept using an all-in-one reactor for hydrogen generation was proposed. • Catalytic reactor, hydrogen chamber and separator were combined in a volume. • The system can be used to drive fuel cell-powered unmanned autonomous systems. - Abstract: Compact fuel cell system was developed for a portable power generator. The power generator features a polymer electrolyte membrane fuel cell (PEMFC) using a chemical hydride as a hydrogen source. The hydrogen generator extracted hydrogen using a catalytic hydrolysis from a sodium borohydride alkaline solution. A novel concept using an all-in-one reactor was proposed in which a catalyst, hydrogen chamber and byproduct separator were combined in a volume. In addition, the reactor as well as a pump, cooling fans, valves and controller was integrated in a single module. A 100 W PEMFC stack was connected with the hydrogen generator and was evaluated at various load conditions. It was verified that the stable hydrogen supply was achieved and the developed system can be used to drive fuel cell-powered unmanned autonomous systems.

  13. Carbon-Supported Pd and PdFe Alloy Catalysts for Direct Methanol Fuel Cell Cathodes

    Directory of Open Access Journals (Sweden)

    Luis M. Rivera Gavidia

    2017-05-01

    Full Text Available Direct methanol fuel cells (DMFCs are electrochemical devices that efficiently produce electricity and are characterized by a large flexibility for portable applications and high energy density. Methanol crossover is one of the main obstacles for DMFC commercialization, forcing the search for highly electro-active and methanol tolerant cathodes. In the present work, carbon-supported Pd and PdFe catalysts were synthesized using a sodium borohydride reduction method and physico-chemically characterized using transmission electron microscopy (TEM and X-ray techniques such as photoelectron spectroscopy (XPS, diffraction (XRD and energy dispersive spectroscopy (EDX. The catalysts were investigated as DMFC cathodes operating at different methanol concentrations (up to 10 M and temperatures (60 °C and 90 °C. The cell based on PdFe/C cathode presented the best performance, achieving a maximum power density of 37.5 mW·cm−2 at 90 °C with 10 M methanol, higher than supported Pd and Pt commercial catalysts, demonstrating that Fe addition yields structural changes to Pd crystal lattice that reduce the crossover effects in DMFC operation.

  14. Partial amino acid sequence of the branched chain amino acid aminotransferase (TmB) of E. coli JA199 pDU11

    International Nuclear Information System (INIS)

    Feild, M.J.; Armstrong, F.B.

    1987-01-01

    E. coli JA199 pDU11 harbors a multicopy plasmid containing the ilv GEDAY gene cluster of S. typhimurium. TmB, gene product of ilv E, was purified, crystallized, and subjected to Edman degradation using a gas phase sequencer. The intact protein yielded an amino terminal 31 residue sequence. Both carboxymethylated apoenzyme and [ 3 H]-NaBH-reduced holoenzyme were then subjected to digestion by trypsin. The digests were fractionated using reversed phase HPLC, and the peptides isolated were sequenced. The borohydride-treated holoenzyme was used to isolate the cofactor-binding peptide. The peptide is 27 residues long and a comparison with known sequences of other aminotransferases revealed limited homology. Peptides accounting for 211 of 288 predicted residues have been sequenced, including 9 residues of the carboxyl terminus. Comparison of peptides with the inferred amino acid sequence of the E. coli K-12 enzyme has helped determine the sequence of the amino terminal 59 residues; only two differences between the sequences are noted in this region

  15. Analysis of interactions of brevetoxin-B and human serum albumin by liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Wang, Zhihong; Ramsdell, John S

    2011-01-14

    Brevetoxins are neurotoxins produced by marine dinoflagellates, primarily Karenia brevis, and can cause intoxication and even mortality of marine species, affect human health through the consumption of brevetoxin-contaminated shellfish, and effect respiratory irritation through aerosol exposure at coastal areas. Brevetoxin-A and brevetoxin-B, the major brevetoxins produced in algae, are metabolized to a series of amino acid and peptide-related derivatives in shellfish through the reactions of the amino acid residue cysteine with an α,β-unsaturated aldehyde group. In this paper, covalent interactions between brevetoxin and proteins were investigated using brevetoxin-B and human serum albumin (HSA) as a model. It is demonstrated that both noncovalent and covalent interactions can occur between brevetoxin-B and HSA with in vitro experiments. Covalent adducts of brevetoxin-B and HSA were generated under physiological conditions and reduced with sodium borohydride based on the reaction conditions of single amino acid residues with brevetoxin-B. LC/MS analysis of toxin-treated HSA recognized the formation of the intact protein adducts with primarily one and two toxin molecules attached to one HSA molecule. HSA treated with/without brevetoxin-B was digested with trypsin, trypsin following chymotrypsin, and Pronase, respectively, for LC/MS analysis of adduction sites. Brevetoxin-B was found to react primarily with Cys(34) and His(3) and with His and Lys at other sites of HSA with variable reactivity and with Lys in general the least reactive.

  16. Preparation of silver nanoparticles/polydopamine functionalized polyacrylonitrile fiber paper and its catalytic activity for the reduction 4-nitrophenol

    Science.gov (United States)

    Lu, Shixiang; Yu, Jianying; Cheng, Yuanyuan; Wang, Qian; Barras, Alexandre; Xu, Wenguo; Szunerits, Sabine; Cornu, David; Boukherroub, Rabah

    2017-07-01

    The study reports on the preparation of polyacrylonitrile fiber paper (PANFP) functionalized with polydopamine (PD) and silver nanoparticles (Ag NPs), named as Ag NPs/PD/PANFP. The composite material was obtained via a simple two-step chemical process. First, a thin polydopamine layer was coated onto the PANFP surface through immersion into an alkaline dopamine (pH 8.5) aqueous solution at room temperature. The reductive properties of polydopamine were further exploited for the deposition of Ag NPs. The morphology and chemical composition of the composite material were characterized using scanning electron microscopy (SEM), X-ray diffraction pattern (XRD) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of the nanocomposite was evaluated for the reduction of 4-nitrophenol using sodium borohydride (NaBH4) at room temperature. The Ag NPs/PD/PANFP displayed good catalytic performance with a full reduction of 4-nitrophenol into the corresponding 4-aminophenol within 30 min. Moreover, the composite material exhibited a good stability up to 4 cycles without a significant loss of its catalytic activity.

  17. Preparation of silver nanoparticles/polydopamine functionalized polyacrylonitrile fiber paper and its catalytic activity for the reduction 4-nitrophenol

    International Nuclear Information System (INIS)

    Lu, Shixiang; Yu, Jianying; Cheng, Yuanyuan; Wang, Qian; Barras, Alexandre; Xu, Wenguo; Szunerits, Sabine; Cornu, David; Boukherroub, Rabah

    2017-01-01

    Graphical abstract: Illustration of the preparation of Ag nanoparticles coated paper and its catalytic application for 4-nitrophenol reduction into the corresponding 4-aminophenol. - Highlights: • Polyacrylonitrile paper was functionalized with polydopamine and Ag nanoparticles. • Polydopamine coating layer played both reductive and adhesive roles. • The composite material displayed good catalytic activity for 4-nitrophenol reduction. • The process was environmentally benign and facile. - Abstract: The study reports on the preparation of polyacrylonitrile fiber paper (PANFP) functionalized with polydopamine (PD) and silver nanoparticles (Ag NPs), named as Ag NPs/PD/PANFP. The composite material was obtained via a simple two-step chemical process. First, a thin polydopamine layer was coated onto the PANFP surface through immersion into an alkaline dopamine (pH 8.5) aqueous solution at room temperature. The reductive properties of polydopamine were further exploited for the deposition of Ag NPs. The morphology and chemical composition of the composite material were characterized using scanning electron microscopy (SEM), X-ray diffraction pattern (XRD) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of the nanocomposite was evaluated for the reduction of 4-nitrophenol using sodium borohydride (NaBH 4 ) at room temperature. The Ag NPs/PD/PANFP displayed good catalytic performance with a full reduction of 4-nitrophenol into the corresponding 4-aminophenol within 30 min. Moreover, the composite material exhibited a good stability up to 4 cycles without a significant loss of its catalytic activity.

  18. 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.

  19. Generation and thermally adjustable catalysis of silver nanoparticle immobilized temperature-sensitive nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jun; Zhou, Tao; Jia, Lei, E-mail: jlxj@hpu.edu.cn; Shen, Xiaoke; Li, Xiaohui; Li, Huijun; Xu, Zhouqing; Cao, Jianliang, E-mail: caojianliang@hpu.edu.cn [Henan Polytechnic University, College of Chemistry and Chemical Engineering (China)

    2017-03-15

    The rise in environmental issues due to the catalytic degradation of pollutants in water has received much attention. In this report, a facile method was developed for the generation of a novel thermosensitive Ag-decorated catalyst, SiO{sub 2}@PNIPAM@Ag (the average particle size is around 540 nm), through atom transfer radical polymerization (ATRP) and mild reducing reactions. First, poly(N-isopropylacrylamide) (PNIPAM) was used to create a shell around mercapto-silica spheres that allowed for enhanced catalyst support dispersion into water. Second, through a mild reducing reaction, these Ag nanoparticles (NPs) were then anchored to the surface of SiO{sub 2}@PNIPAM spheres. The resulting catalyst revealed catalytic activity to degrade various nitrobenzenes and organic dyes in an aqueous solution with sodium borohydride (NaBH{sub 4}) at ambient temperature. The catalytic activity can be adjusted in different temperatures through the aggregation or dispersion of Ag catalyst on the polymer supporters, which is due to the thermosensitive PNIPAM shell. The ease of preparation and efficient catalytic activity of the catalyst can make it a promising candidate for the use in degrading organic pollutants for environmental remediation.

  20. Preparation of Nanofibrous Silver/Poly(vinylidene fluoride) Composite Membrane with Enhanced Infrared Extinction and Controllable Wetting Property.

    Science.gov (United States)

    Ren, Da-Ming; Huang, Hua-Kun; Yu, Yun; Li, Zeng-Tian; Jiang, Li-Wang; Chen, Shui-Mei; Lam, Kwok-Ho; Lin, Bo; Shi, Bo; He, Fu-An; Wu, Hui-Jun

    2018-05-01

    Nanofibrous silver (Ag)/poly(vinylidene fluoride) (PVDF) composite membranes were obtained from a two-step preparation method. In the first step, the electrospun silver nitrate (AgNO3)/PVDF membranes were prepared and the influence of the AgNO3 content on the electrospinning process was studied. According to scanning electron microscopy (SEM) results, when the electrospinning solution contained AgNO3 in the range between 3 to 7 wt.%, the nanofiber morphologies can be obtained. In the second step, the electrospun AgNO3/PVDF membranes were reduced by sodium borohydride to form the nanofibrous Ag/PVDF composite membranes. The resultant composite membranes were characterized by SEM, X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), differential scanning calorimetry, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared. The XRD, XPS, and EDS characterizations proved the existence of Ag in the nanofibrous Ag/PVDF composite membranes. The crystallinity degree of PVDF for composite membranes declined with the increase in Ag content. More importantly, the nanofibrous Ag/PVDF composite membranes had obviously higher Rosseland extinction coefficients and lower thermal radiative conductivities in comparison with electrospun PVDF membrane, which demonstrates that such composite membranes with high porosity, low density, and good water vapor permeability are promising thermal insulating materials to block the heat transfer resulting from thermal radiation. In addition, three different methods for surface modification have been used to successfully improve the hydrophobicity of nanofibrous Ag/PVDF composite membranes.

  1. Synthesis and characterization of silver/talc nanocomposites using the wet chemical reduction method

    Science.gov (United States)

    Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Zin Wan; Ibrahim, Nor Azowa; Darroudi, Majid

    2010-01-01

    In this study, silver nanoparticles (Ag-NPs) were synthesized using the wet chemical reduction method on the external surface layer of talc mineral as a solid support. Silver nitrate and sodium borohydride were used as the silver precursor and reducing agent in talc. The talc was suspended in aqueous AgNO3 solution. After the absorption of Ag+ on the surface, the ions were reduced with NaBH4. The interlamellar space limits were without many changes (ds = 9.34–9.19 Aº); therefore, Ag-NPs formed on the exterior surface of talc, with dave = 7.60–13.11 nm in diameter. The properties of Ag/talc nanocomposites (Ag/talc-NCs) and the diameters of the Ag-NPs prepared in this way depended on the primary AgNO3 concentration. The prepared Ag-NPs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared. These Ag/talc-NCs may have potential applications in the chemical and biological industries. PMID:21042420

  2. Ultrathin Bi2WO6 nanosheet decorated with Pt nanoparticles for efficient formaldehyde removal at room temperature

    Science.gov (United States)

    Sun, Dong; Le, Yao; Jiang, Chuanjia; Cheng, Bei

    2018-05-01

    Two-dimensional (2D) ultrathin bismuth tungstate (Bi2WO6) nanosheets (BWO-NS) with a thickness of approximately 4.0 nm were synthesized by a one-step hydrothermal method, and decorated with platinum (Pt) nanoparticles (NPs) via an impregnation/borohydride-reduction approach. The as-prepared ultrathin Pt-BWO-NS exhibited superior catalytic activity for removing gaseous formaldehyde (HCHO) at ambient temperature, in comparison with bulk counterpart with Bi2WO6 sheet thickness of tens of nanometers. The ultrathin structure endowed the Pt-BWO-NS sample with larger specific surface area, which can provide abundant surface active sites for HCHO adsorption and facilitate the homogeneous dispersion of Pt NPs. X-ray photoelectron spectroscopy and hydrogen temperature-programmed reduction analyses revealed the interaction between the Bi2WO6 support and Pt species, which is crucial for activating surface oxygen atoms to participate in the catalytic HCHO oxidation process. By conducting in situ diffuse reflectance infrared Fourier transform spectroscopy under different atmospheres, i.e., gaseous HCHO in nitrogen or oxygen (O2), the reaction mechanism and the role of O2 were elucidated, with dioxymethylene, formate and linearly adsorbed carbon monoxide identified as the main reaction intermediates. This study may provide new enlightenment on fabricating novel 2D nanomaterials for efficient indoor air purification and potentially other environmental applications.

  3. Synthesis of self-assembly plasmonic silver nanoparticles with tunable luminescence color

    International Nuclear Information System (INIS)

    Al-Ghamdi, Haifa S.; Mahmoud, Waleed E.

    2014-01-01

    Assembly is an elegant and effective bottom-up approach to prepare arrays of nanoparticles from nobel metals. Noble metal nanoparticles are perfect building blocks because they can be prepared with an adequate functionalization to allow their assembly and with controlled sizes. Herein, we report a novel recipe for the synthesis of self-assembled silver nanoparticles with tunable optical properties and sizes. The synthetic route followed here based on the covalent binding among silver nanoparticles by means of poly vinyl alcohol for the first time. The size of silver nanoparticle is governed by varying the amount of sodium borohydride. The as-synthesized nanoparticles were characterized by transmission electron microscopy, x-ray diffraction, energy dispersive x-ray spectroscopy, selected area electron diffraction and UV–vis spectroscopy. Results depicted that self-assembly of mono-dispersed silver nanoparticles with different sizes have been achieved. The silver nanostructure has a single crystalline faced centered cubic structure with growth orientation along (1 1 1) facet. These nanoparticles exhibited localized surface plasmon resonance at 403 nm. The luminescence peaks were red-sifted from violet to green due to the increase of the particle sizes. -- Highlights: • Self-assembled silver nanoparticles based PVA were synthesized. • NaBH 4 amount was found particle size dependent. • Silver nanoparticles strongly affected the surface plasmon resonance. • Highly symmetric luminescence emission band narrow width is obtained. • Dark field image showed a tunable color change from violet to green

  4. Kyllinga brevifolia mediated greener silver nanoparticles

    Science.gov (United States)

    Isa, Norain; Bakhari, Nor Aziyah; Sarijo, Siti Halimah; Aziz, Azizan; Lockman, Zainovia

    2017-12-01

    Kyllinga brevifolia extract (KBE) was studied in this research as capping as well as reducing agent for the synthesis of greener plant mediated silver nanoparticles. This research was conducted in order to identify the compounds in the KBE that probable to work as reductant for the synthesis of Kyllinga brevifolia-mediated silver nanoparticles (AgNPs). Screening test such as Thin Layer Chromatography (TLC), Fourier Transform Infra-Red (FTIR), Carlo Erba Elemental analysis and Gas Chromatography-Mass Spectroscopy (GCMS) were used in identifying the natural compounds in KBE. The as-prepared AgNPs were characterized by UV-vis spectroscopy (UV-vis), Transmission Electron Microscope (TEM) and X-ray Diffraction (XRD). The TEM images showed that the as-synthesized silver have quasi-spherical particles are distributed uniformly with a narrow distribution from 5 nm to 40 nm. The XRD results demonstrated that the obtained AgNPs were face centre-cubic (FCC) structure. The catalytic activity of AgNPs on reduction of methylene blue (MB) using sodium borohydride (SB) was analyzed using UV-vis spectroscopy. This study showed that the efficacy of mediated AgNPs in catalysing the reduction of MB.

  5. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Preparation of Silver Nanostructures from Bicontinuous Microemulsions

    Directory of Open Access Journals (Sweden)

    M. A. Pedroza-Toscano

    2012-01-01

    Full Text Available 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 diffraction, and atomic absorption spectroscopy. A mixture of isolated spheroidal nanoparticles (≈15 wt.% with an average diameter around 10 nm and wormlike structures (≈85 wt.% with an average length close to 480 nm and an average diameter ca. 40 nm was obtained, regardless of the AOT/SDS ratio. Higher yields were obtained compared with those reported when reverse microemulsions were employed. Formation of wormlike structures was ascribed to one-dimensional aggregation of crystal and particles within the channels of bicontinuous microemulsions, which performed as templates.

  7. Silver Nanoparticles Obtained by Semicontinuous Chemical Reduction Using Carboxymethyl Cellulose as a Stabilizing Agent and Its Antibacterial Capacity

    Directory of Open Access Journals (Sweden)

    M. A. Pedroza-Toscano

    2017-01-01

    Full Text Available Preparation of silver nanoparticles was carried out by semicontinuous reduction of Ag+ ions at low temperatures. Silver nitrate was used as the Ag0 precursor, the carboxymethyl cellulose (CMC as stabilizer and primary reducing agent, and sodium borohydride as reducing agent. Weight ratios of 1 : 1 and 1 : 2 of AgNO3 : CMC were used for carrying out the reactions. Silver nanoparticles were characterized by UV-VIS spectroscopy, transmission electronic microscopy (TEM, and X-ray diffraction (XRD. The formation of silver nanoparticles was confirmed by XRD spectroscopy and by the presence of an absorption peak around 400 nm in the UV-visible spectrum. Unimodal size distributions of spheroidal nanoparticles were observed by TEM. Greater productivities than those reported by other authors were obtained with the advantage of using a lower temperature and minor reaction times. By using a higher CMC/AgNO3 weight ratio or a higher concentration of AgNO3, AgNPs with larger average size were produced. Antibacterial activity of AgNPs against S. aureus and E. coli was determined by the agar disk diffusion method. The higher the AgNPs concentration, the larger the inhibition zone. The minimum inhibitory concentration (MIC of AgNPs against S. aureus and E. coli was 5 μg/disk.

  8. Nucleation and growth of gold nanoparticles studied via in situ small angle X-ray scattering at millisecond time resolution.

    Science.gov (United States)

    Polte, Jörg; Erler, Robert; Thünemann, Andreas F; Sokolov, Sergey; Ahner, T Torsten; Rademann, Klaus; Emmerling, Franziska; Kraehnert, Ralph

    2010-02-23

    Gold nanoparticles (AuNP) were prepared by the homogeneous mixing of continuous flows of an aqueous tetrachloroauric acid solution and a sodium borohydride solution applying a microstructured static mixer. The online characterization and screening of this fast process ( approximately 2 s) was enabled by coupling a micromixer operating in continuous-flow mode with a conventional in-house small angle X-ray scattering (SAXS) setup. This online characterization technique enables the time-resolved investigation of the growth process of the nanoparticles from an average radius of ca. 0.8 nm to about 2 nm. To the best of our knowledge, this is the first demonstration of a continuous-flow SAXS setup for time-resolved studies of nanoparticle formation mechanisms that does not require the use of synchrotron facilities. In combination with X-ray absorption near edge structure microscopy, scanning electron microscopy, and UV-vis spectroscopy the obtained data allow the deduction of a two-step mechanism of gold nanoparticle formation. The first step is a rapid conversion of the ionic gold precursor into metallic gold nuclei, followed by particle growth via coalescence of smaller entities. Consequently it could be shown that the studied synthesis serves as a model system for growth driven only by coalescence processes.

  9. Natural polymers supported copper nanoparticles for pollutants degradation

    Science.gov (United States)

    Haider, Sajjad; Kamal, Tahseen; Khan, Sher Bahadar; Omer, Muhammad; Haider, Adnan; Khan, Farman Ullah; Asiri, Abdullah M.

    2016-11-01

    In this report, chitosan (CS) was adhered on cellulose microfiber mat (CMM) to prepare CS-CMM. This was used as host for copper (Cu) nanoparticles preparation. After adsorption of Cu2+ ions from an aqueous solution of CuSO4, the metal ions entrapped in CS coating layer was treated with sodium borohydride (NaBH4) to prepare Cu nanoparticles loaded CS-CMM (Cu/CS-CMM). Fourier transform infrared spectroscopy, and X-ray diffraction confirmed the formation of Cu/CS-CMM hybrid. Scanning electron microscopy analysis was performed to reveal the morphology of the prepared catalyst. The prepared Cu/CS-CMM was employed as a catalyst for the degradation of nitro-aromatic compounds of 2-nitrophenol (2NP) and 4-nitrophenol (4NP) as well as an organic cresyl blue (CB) dye. Remarkably, the turnover frequency in the case of 2NP and 4NP using Cu/CS-CMM reaches 103.3 and 88.6 h-1, outperforming previously reported Cu nanoparticles immobilized in hydrogel-based catalytic systems. The rate constants for 2NP, 4NP and CB were 1.2 × 10-3 s-1, 2.1 × 10-3 s-1 and, 1.3 × 10-3 s-1, respectively. Besides, we discussed the separation of the catalyst from the reaction mixture and its re-usability.

  10. Synthesis and characterization of zero-valent iron nanoparticles supported on SBA-15

    Directory of Open Access Journals (Sweden)

    Felipe Sombra dos Santos

    2017-04-01

    Full Text Available This paper aims to synthesize zero-valent iron nanoparticles (nZVI supported on SBA-15 nanosilica. The nanosilica generate in the system by polymer reaction with hydrochloric acid under controlled temperature. After, the iron nanomaterial was obtained by sodium borohydride reduction as described in this work. Afterward the synthesis of the nanoparticles contained iron supported on silica SBA-15, the material was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, zeta potential and X-ray fluorescence spectroscopy. The results indicated that nanomaterial obtained was in nanometric scale, by TEM results, and showing characteristic peaks at EDS results, with 11.9% iron and 14.0% silicon content, respectively, and containing 73.0% and 27.0% of their respective oxides through X-ray fluorescence spectroscopy. The isoelectric potential of the sample was around 2.0, close to the value reported for silica, due to the higher percentage of silica in the sample when compared to iron. The obtained material can be used, for some cases, as an possible alternative, to the Fenton reaction for the degradation of xenobiotic compounds or other applications in the groundwater and wastewater treatments.

  11. Natural cotton as precursor for the refractory boron carbide—a hydrothermal synthesis and characterization

    Science.gov (United States)

    Saritha Devi, H. V.; Swapna, M. S.; Raj, Vimal; Ambadas, G.; Sankararaman, S.

    2018-01-01

    Boron carbide (B4C) is an excellent covalent carbide that finds applications in industries and nuclear power plants. The present synthesis methods of boron carbide are expensive and involve the use of toxic chemicals that adversely affect environment. In the present work, we report for the first time the use of the hydrothermal method for converting the cellulose from cotton as the carbon precursor for B4C. The carbon precursor is converted into functionalized porous carbonaceous material by hydrothermal treatment followed by sodium borohydride. It is further treated with boric acid to make it a B4C precursor. The precursor is characterized by UV-visible diffuse reflectance, Raman, Fourier transform infrared, photoluminescent and energy dispersive spectroscopy. The morphology and structure analysis is carried out using field emission scanning electron microscopy and x-ray diffraction techniques. The results of structural and optical characterization of the sample synthesized are compared with the commercial B4C. The thermal stability of the sample is studied by thermogravimetric analysis. The sample annealed at 700 °C is found to be B4C devoid of amorphous carbon with a yield of 44.7%. The analysis reveals the formation of boron carbide from the sample.

  12. Novel Co(OH)2 with cotton-like structure as anode material for alkaline secondary batteries

    Science.gov (United States)

    Zhao, W.; Liao, Y. L.; Qiu, S. J.; Chu, H. L.; Zou, Y. J.; Xiang, C. L.; Zhang, H. Z.; Xu, F.; Sun, L. X.

    2018-01-01

    The cotton-like Co(OH)2 (S-Co(OH)2) was successfully synthesized and its electrochemical performance was systematically investigated. S-Co(OH)2 was prepared through the “destruction” of the newly formed colloid Co(OH)2 by the reduction using sodium borohydride. The crystal structure and surface morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Used as an anode material for alkaline secondary batteries, S-Co(OH)2 sample exhibited better cycle stability, higher electrochemical capacity, and higher rate performance than those of conventional β-Co(OH)2. At a discharge current density of 100 mA/g, the initial discharge capacity of S-Co(OH)2 is 549.3 mAh/g and the discharge capacity is still sustained to be 329.2 mAh/g after 100 charge-discharge cycles with a capacity retention of 59.9%.

  13. Slurry analysis of cadmium and copper collected on 11-mercaptoundecanoic acid modified TiO2 core-Au shell nanoparticles by flame atomic absorption spectrometry.

    Science.gov (United States)

    Gunduz, S; Akman, S; Kahraman, M

    2011-02-15

    Separation/preconcentration of copper and cadmium using TiO(2) 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. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Antimicrobial chitosan-PVA hydrogel as a nanoreactor and immobilizing matrix for silver nanoparticles

    Science.gov (United States)

    Agnihotri, Shekhar; Mukherji, Soumyo; Mukherji, Suparna

    2012-09-01

    Hydrogels are water-insoluble crosslinked hydrophilic networks capable of retaining a large amount of water. The present work aimed to develop a novel chitosan-PVA-based hydrogel which could behave both as a nanoreactor and an immobilizing matrix for silver nanoparticles (AgNPs) with promising antibacterial applications. The hydrogel containing AgNPs were prepared by repeated freeze-thaw treatment using varying amounts of the crosslinker, followed by in situ reduction with sodium borohydride as a reducing agent. Characterization studies established that the hydrogel provides a controlled and uniform distribution of nanoparticles within the polymeric network without addition of any further stabilizer. The average particle size was found to be 13 nm with size distribution from 8 to 21 nm as per HR-TEM studies. Swelling studies confirmed that higher amount of crosslinker and silver incorporation inside the gel matrices significantly enhanced the porosity and chain entanglement of the polymeric species of the hydrogel, respectively. The AgNP-hydrogel exhibited good antibacterial activity and was found to cause significant reduction in microbial growth ( Escherichia coli) in 12 h while such activity was not observed for the hydrogel without AgNPs.

  15. Hydrothermal development and characterization of the wear-resistant boron carbide from Pandanus: a natural carbon precursor

    Science.gov (United States)

    Saritha Devi, H. V.; Swapna, M. S.; Ambadas, G.; Sankararaman, S.

    2018-04-01

    Boron carbide (B4C) is a prominent semiconducting material that finds applications in the field of science and technology. The excellent physical, thermal and electronic properties make it suitable as ceramic armor, wear-resistant, lens polisher and neutron absorber in the nuclear industry. The existing methods of synthesis of boron carbide involve the use of toxic chemicals that adversely affect the environment. In the present work, we report for the first time the use of the hydrothermal method, for converting the cellulose from Pandanus leaves as the carbon precursor for the synthesis of B4C. The carbon precursor is changed into porous functionalized carbon by treating with sodium borohydride (NaBH4), followed by treating with boric acid to obtain B4C. The samples are characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared, Raman, photoluminescent and Ultraviolet-Visible absorption spectroscopy. The formation of B4C from natural carbon source— Pandanus presents an eco-friendly, economic and non-toxic approach for the synthesis of refractory carbides.

  16. Preparation and characterization of biocompatible silver nanoparticles using pomegranate peel extract.

    Science.gov (United States)

    Nasiriboroumand, Majid; Montazer, Majid; Barani, Hossein

    2018-02-01

    The potential application of any nanoparticles, including silver nanoparticles (AgNPs), strongly depends on their stability against aggregation. In the current study, an aqueous extract of pomegranate peel was used as a stabilizer during synthesis of AgNPs. Nanoparticles have been prepared by the chemical reduction method from an aqueous solution of silver nitrate in the presence of sodium borohydride as a reducing agent. The AgNPs were characterized by dynamic light scattering (DLS), zeta-potential measurements, UV-Vis spectroscopy and transmission electron microscopy (TEM). The antibacterial efficiency of AgNPs against Escherichia coli was investigated. The size, polydispersity index, FWHM, and colloidal stability of nanoparticles in dispersion depends on the extract concentrations. In the presence of pomegranate peel extract, the nanoparticles suspension shows colloidal stability at least for a week. Our studies show that synthesized AgNPs with the above described procedure were stable at pH = 3-12 and in the temperature range of 25-85 °C. Additionally, AgNPs exhibit antibacterial properties, especially at the lowest amount of extract to silver ratio (K Extract/Ag ). Copyright © 2018. Published by Elsevier B.V.

  17. 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. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. 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 %.

  19. Use of 6α- and 6β-carboxymethyl testosterone-bovine serum albumin conjugates in radioimmunoassay for testosterone

    International Nuclear Information System (INIS)

    Jones, C.D.; Mason, N.R.

    1975-01-01

    The synthesis of 6α- and 6β-testosterone-bovine serum albumin (BSA) conjugates is described. 6β-Carboxymethyl-4-androstene-3,17-dione was prepared by a route analogous to that described earlier for 6β-carboxymethyl progesterone. Sodium borohydride reduction of the 3 and 17 keto groups and subsequent selective oxidation of the resulting 3β,17β-diol using MnO 2 provided 6β-carboxymethyl testosterone. Further acid catalyzed epimerization of the C-6 center gave the isomeric 6α-carboxymethyl testosterone. The 6α- and 6β-testosterone derivatives were attached to BSA via a mixed anhydride coupling employing tributylamine and i-butylchlorocarbonate. For each molecule of BSA, the 6α- and 6β-conjugates contained an average of 23 and 20 steroid residues, respectively. Antisera to the conjugates exhibited similar high specificities toward various steroids, the only incidence of serious cross-reaction being the expected case of dihydrotestosterone. (U.S.)

  20. Slurry analysis of cadmium and copper collected on 11-mercaptoundecanoic acid modified TiO{sub 2} core-Au shell nanoparticles by flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Gunduz, S. [Istanbul Technical University, Faculty of Science and Letters, Department of Chemistry, 34469 Maslak-Istanbul (Turkey); Akman, S., E-mail: akmans@itu.edu.tr [Istanbul Technical University, Faculty of Science and Letters, Department of Chemistry, 34469 Maslak-Istanbul (Turkey); Kahraman, M. [Yeditepe University, Faculty of Engineering and Architecture, Department of Genetics and Bioengineering, 34755 Kayisdagi-Istanbul (Turkey)

    2011-02-15

    Separation/preconcentration of copper and cadmium using TiO{sub 2} 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, 3{sigma}) for copper and cadmium were 0.28 and 0.15 ng mL{sup -1}, respectively.

  1. Synthesis Optimisation of Lysozyme Monolayer-Coated Silver Nanoparticles in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    A. V. Yakovlev

    2014-01-01

    Full Text Available This paper presents an optimisation of the synthesis of silver nanoparticles encapsulated in a biological shell. The synthesis was carried out in an aqueous solution of silver nitrate. Sodium borohydride was used as a reducing agent. Lysozyme served as a bioactive coating agent. The samples produced were studied using dynamic light scattering, transmission electron microscopy, and UV-Vis spectroscopy. The function of the dependence of the reagent ratio in obtained sols on optical properties is shown. Furthermore, the influence of the synthesis temperature, reactant ratio, and order of mixing on the particle size distribution parameters is shown. The optimal reagent mass ratio, NaBH4 : LYZ : AgNO3 = 0.22 : 0.77 : 1, is established. The resulting composition allows the synthesis of particles with a mean diameter of 18 nm and a bioshell thickness of ≈3.5 nm. Moreover, the necessity of the synthesis optimisation and precise parameter control is clearly demonstrated.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. - Highlights: • A new type of antibacterial agent (PSA/Ag-NPs nanocomposites) was synthesized. • The antibacterial activity against S. aureus and E. coli was studied. • Inhibition zone, MIC, MBC, and bactericidal kinetics were evaluated. • PSA/Ag-NPs nanocomposites showed excellent antibacterial activity

  3. Surface plasmon resonance of Ag organosols: Experimental and theoretical investigations

    Directory of Open Access Journals (Sweden)

    Vodnik Vesna

    2012-01-01

    Full Text Available The aim of this paper is to investigate and compare the changes in surface plasmon resonance (SPR of silver (Ag hydrosol and organosols obtained by experimental and theoretical approaches. Silver nanoparticles (Ag NPs of 5 ± 1.5 nm in diameter were prepared in water by reduction of silver nitrate with sodium borohydride. Nanoparticles were subsequently transferred into different organic solvents (chloroform, hexane, toluene, 1,2-dichlorobenzene using oleylamine as a transfer agent. These solvents were chosen because of the differences in their refractive indices. Using UV-Vis absorption spectrophotometry and transmission electron microscopy (TEM, we confirmed that there were no shape and size changes of the nanoparticles upon the transfer to the organic phase. The absorption spectra of the obtained Ag organosols showed only changes in the position of SPR band depending on dielectric property of the used solvent. To analyze these changes, absorption spectra were modelled using Mie theory for small spherical particles. The experimental and theoretical resonance values were compared with those predicted by Drude model and its limitations in the analysis of absorption behavior of Ag NPs in organic solvents were briefly discussed.

  4. Size- and Shape-Dependent Antibacterial Studies of Silver Nanoparticles Synthesized by Wet Chemical Routes

    Directory of Open Access Journals (Sweden)

    Muhammad Akram Raza

    2016-04-01

    Full Text Available Silver nanoparticles (AgNPs of different shapes and sizes were prepared by solution-based chemical reduction routes. Silver nitrate was used as a precursor, tri-sodium citrate (TSC and sodium borohydride as reducing agents, while polyvinylpyrrolidone (PVP was used as a stabilizing agent. The morphology, size, and structural properties of obtained nanoparticles were characterized by scanning electron microscopy (SEM, UV-visible spectroscopy (UV-VIS, and X-ray diffraction (XRD techniques. Spherical AgNPs, as depicted by SEM, were found to have diameters in the range of 15 to 90 nm while lengths of the edges of the triangular particles were about 150 nm. The characteristic surface plasmon resonance (SPR peaks of different spherical silver colloids occurring in the wavelength range of 397 to 504 nm, whereas triangular particles showed two peaks, first at 392 nm and second at 789 nm as measured by UV-VIS. The XRD spectra of the prepared samples indicated the face-centered cubic crystalline structure of metallic AgNPs. The in vitro antibacterial properties of all synthesized AgNPs against two types of Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli were examined by Kirby–Bauer disk diffusion susceptibility method. It was noticed that the smallest-sized spherical AgNPs demonstrated a better antibacterial activity against both bacterial strains as compared to the triangular and larger spherical shaped AgNPs.

  5. 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.

  6. The role of reducing agents in the nucleation and growth of Al metalloid clusters: Ab initio molecular dynamic study

    Science.gov (United States)

    Alnemrat, Sufian

    2017-06-01

    Ab initio simulations are used to study the growth of metalloid aluminum clusters from their monohalide (AlCl) precursors. Molecular dynamics (MD) simulation is used to study the role of reducing agents in the growth process of Al metalloid clusters. Car-Parrinello MD simulations of AlCl liquid and Lithium-Aluminum Hydride reducing agent (LiAlH4) show spontaneous metalloid cluster growth. The growth process is initiated by transferring a proton to a nearby Al atom that helps forming trivalent impurities (AlCl3) in the solution. Growth towards larger metalloid clusters then proceeds via repeated insertion of AlCl into Al-Cl bonds as well as elimination of AlCl3 species. The transferred proton plays a significant role in reducing additional monohalide species from the solution. The energy barrier associated with the Al-Cl bond is dropped from 7.8 eV to 4 eV via proton-hopping between Al centers. However, this process is completely prohibited in the case of sodium borohydride (NaBH4) reducing agent due to strong Coulomb interactions between Na and B centers. Repeated insertion of additional AlCl monomers towards larger clusters was not observed within the same time scale of the previous simulations.

  7. Cobalt-boron amorphous alloy prepared in water/cetyl-trimethyl-ammonium bromide/n-hexanol microemulsion as anode for alkaline secondary batteries

    International Nuclear Information System (INIS)

    Tong, D.G.; Wang, D.; Chu, W.; Sun, J.H.; Wu, P.

    2010-01-01

    Amorphous cobalt-boron (Co-B) with uniform nanoparticles was prepared for the first time via reduction of cobalt acetate by potassium borohydride in the water/cetyl-trimethyl-ammonium bromide/n-hexanol microemulsion system. The sample was characterized by X-ray diffraction, transmission electron microscopy, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, inductively coupled plasma, cyclic voltammetry, differential scanning calorimetry, temperature-programmed desorption, scanning electron microscopy, charge-discharge test and electrochemical impedance spectra. The results demonstrate that electrochemical activity of the as-synthesized Co-B was higher than that of the regular Co-B prepared in aqueous solution. It indicates that the homogeneous distribution and large specific surface area helped the electrochemical hydrogen storage of the as-synthesized Co-B. Furthermore, the as-synthesized Co-B even had 347 mAh g -1 after 50 cycles, while the regular Co-B prepared in aqueous solution only had 254 mAh g -1 after 30 cycles at a current of 100 mA g -1 . The better cycling performance can be ascribed to its smaller interfacial impedance between electrode and electrolyte.

  8. Spontaneous formation of gold nanostructures in aqueous microdroplets.

    Science.gov (United States)

    Lee, Jae Kyoo; Samanta, Devleena; Nam, Hong Gil; Zare, Richard N

    2018-04-19

    The synthesis of gold nanostructures has received widespread attention owing to many important applications. We report the accelerated synthesis of gold nanoparticles (AuNPs), as well as the reducing-agent-free and template-free synthesis of gold nanoparticles and nanowires in aerosol microdroplets. At first, the AuNP synthesis are carried out by fusing two aqueous microdroplet streams containing chloroauric acid and sodium borohydride. The AuNPs (~7 nm in diameter) are produced within 60 µs at the rate of 0.24 nm µs -1 . Compared to bulk solution, microdroplets enhance the size and the growth rate of AuNPs by factors of about 2.1 and 1.2 × 10 5 , respectively. Later, we find that gold nanoparticles and nanowires (~7 nm wide and >2000 nm long) are also formed in microdroplets in the absence of any added reducing agent, template, or externally applied charge. Thus, water microdroplets not only accelerate the synthesis of AuNPs by orders of magnitude, but they also cause spontaneous formation of gold nanostructures.

  9. Electrospun nanofibers decorated with bio-sonochemically synthesized gold nanoparticles as an ultrasensitive probe in amalgam-based mercury (II) detection system.

    Science.gov (United States)

    Parsaee, Zohreh

    2018-06-01

    In this study, bio-ultrasound-assisted synthesized gold nanoparticles using Gracilaria canaliculata algae have been immobilized on a polymeric support and used as a glassy probe chemosensor for detection and rapid removal of Hg 2+ ions. The function of the suggested chemosensor has been explained based on gold-amalgam formation and its catalytic role on the reaction of sodium borohydride and rhodamine B (RhB) with fluorescent and colorimetric sensing function. The catalyzed reduction of RhB by the gold amalgam led to a distinguished color change from red and yellow florescence to colorless by converting the amount of Hg 2+ deposited on Au-NPs. The detection limit of the colorimetric and fluorescence assays for Hg 2+ was 2.21 nM and 1.10 nM respectively. By exposing the mentioned colorless solution to air for at least 2 h, unexpectedly it was observed that the color and fluorescence of RhB were restored. Have the benefit of the above phenomenon a recyclable and portable glass-based sensor has been provided by immobilizing the Au-NPs and RB on the glass slide using electrospinning. Moreover, the introduced combinatorial membrane has facilitated the detection and removal of Hg 2+ ions in various Hg (II)-contaminated real water samples with efficiency of up to 99%. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Recovery of high purity precious metals from printed circuit boards

    International Nuclear Information System (INIS)

    Park, Young Jun; Fray, Derek J.

    2009-01-01

    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(NH 4 ) 2 Cl 6 . 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.

  11. Cerebral biochemical abnormalities in experimental maternal phenylketonuria: gangliosides and sialoglycoproteins

    International Nuclear Information System (INIS)

    Loo, Y.H.; Hyde, K.R.; Lin, F.H.; Wisniewski, H.M.

    1985-01-01

    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 D 3 , was a slower rise in M 1 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 ( 3 H) sialic acid released by neuraminidase from periodate-( 3 H) 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

  12. Importance of the terminal α-amino group of bradykinin and some kynins on capillary permeability increase

    International Nuclear Information System (INIS)

    Sugavara, S.

    1979-01-01

    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) [pt

  13. Optimizing Performance Parameters of Chemically-Derived Graphene/p-Si Heterojunction Solar Cell.

    Science.gov (United States)

    Batra, Kamal; Nayak, Sasmita; Behura, Sanjay K; Jani, Omkar

    2015-07-01

    Chemically-derived graphene have been synthesized by modified Hummers method and reduced using sodium borohydride. To explore the potential for photovoltaic applications, graphene/p-silicon (Si) heterojunction devices were fabricated using a simple and cost effective technique called spin coating. The SEM analysis shows the formation of graphene oxide (GO) flakes which become smooth after reduction. The absence of oxygen containing functional groups, as observed in FT-IR spectra, reveals the reduction of GO, i.e., reduced graphene oxide (rGO). It was further confirmed by Raman analysis, which shows slight reduction in G-band intensity with respect to D-band. Hall effect measurement confirmed n-type nature of rGO. Therefore, an effort has been made to simu- late rGO/p-Si heterojunction device by using the one-dimensional solar cell capacitance software, considering the experimentally derived parameters. The detail analysis of the effects of Si thickness, graphene thickness and temperature on the performance of the device has been presented.

  14. PtNi supported on binary metal oxides: Potential bifunctional electrocatalysts for low-temperature fuel cells?

    Science.gov (United States)

    Martins, M.; Šljukić, B.; Sequeira, C. A. C.; Soylu, G. S. P.; Yurtcan, A. B.; Bozkurt, G.; Sener, T.; Santos, D. M. F.

    2018-01-01

    PtNi nanoparticles (NPs) were synthesised by microwave irradiation technique and supported onto Mn2O3 and two binary metal oxides, Mn2O3-TiO2 and Mn2O3-NiO, prepared by solid-state dispersion method. TEM analysis revealed formation of PtNi NPs of 2-3 nm diameter on the metal oxides. Their activity for oxygen reduction reaction (ORR) and borohydride oxidation reaction (BOR) in alkaline media was studied using voltammetric, amperometric and electrochemical impedance spectroscopy techniques. The effect of electrolyte composition and operation temperature on the catalysts performance was also examined. ORR and BOR kinetic parameters, namely Tafel slope, kinetic current density, order of reaction and activation energy were evaluated, enabling direct comparison of the three electrocatalysts performance. The results show that PtNi NPs anchored on binary metal oxide supports possess superior activity for BOR in alkaline media, suggesting their potential application as anodes in low-temperature fuel cells.

  15. 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)

    Lezama C, J.; Ferro F, G.; Alcazar A, P.

    1991-09-01

    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 ( 99 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. 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)

  16. Fabrication of CdTe/Si heterojunction solar cell

    Science.gov (United States)

    Bera, Swades Ranjan; Saha, Satyajit

    2016-10-01

    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.

  17. Green reduction of graphene oxide by ascorbic acid

    Science.gov (United States)

    Khosroshahi, Zahra; Kharaziha, Mahshid; Karimzadeh, Fathallah; Allafchian, Alireza

    2018-01-01

    Graphene, a single layer of sp2-hybridized carbon atoms in a hexagonal (two-dimensional honey-comb) lattice, has attracted strong scientific and technological interest due to its novel and excellent optical, chemical, electrical, mechanical and thermal properties. The solution-processable chemical reduction of Graphene oxide (GO is considered as the most favorable method regarding mass production of graphene. Generally, the reduction of GO is carried out by chemical approaches using different reductants such as hydrazine and sodium borohydride. These components are corrosive, combustible and highly toxic which may be dangerous for personnel health and the environment. Hence, these reducing agents are not promising choice for reducing of graphene oxide (GO). As a consequence, it is necessary for further development and optimization of eco-friendly, natural reducing agent for clean and effective reduction of GO. Ascorbic acid, an eco-friendly and natural reducing agents, having a mild reductive ability and nontoxic property. So, the aim of this research was to green synthesis of GO with ascorbic acid. For this purpose, the required amount of NaOH and ascorbic acid were added to GO solution (0.5 mg/ml) and were heated at 95 °C for 1 hour. According to the X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electrochemical results, GO were reduced with ascorbic acid like hydrazine with better electrochemical properties and ascorbic acid is an ideal substitute for hydrazine in the reduction of graphene oxide process.

  18. One-Pot Green Synthesis of Ag-Decorated SnO2 Microsphere: an Efficient and Reusable Catalyst for Reduction of 4-Nitrophenol

    Science.gov (United States)

    Hu, Min; Zhang, Zhenwei; Luo, Chenkun; Qiao, Xiuqing

    2017-06-01

    In this paper, hierarchical Ag-decorated SnO2 microspheres were synthesized by a facile one-pot hydrothermal method. The resulting composites were characterized by XRD, SEM, TEM, XPS, BET, and FTIR analysis. The catalytic performances of the samples were evaluated with the reduction of 4-nitrophenol to 4-aminophenol by potassium borohydride (KBH4) as a model reaction. Time-dependent experiments indicated that the hierarchical microspheres assembled from SnO2 and Ag nanoparticles can be formed when the react time is less than 10 h. With the increase of hydrothermal time, SnO2 nanoparticles will self-assemble into SnO2 nanosheets and Ag nanoparticles decorated SnO2 nanosheets were obtained. When evaluated as catalyst, the obtained Ag-decorated SnO2 microsphere prepared for 36 h exhibited excellent catalytic performance with normalized rate constant ( κ nor) of 6.20 min-1g-1L, which is much better than that of some previous reported catalysts. Moreover, this Ag-decorated SnO2 microsphere demonstrates good reusability after the first five cycles. In addition, we speculate the formation mechanism of the hierarchical Ag-decorated SnO2 microsphere and discussed the possible origin of the excellent catalytic activity.

  19. Facile synthesis of palladium nanocatalyst using gum kondagogu (Cochlospermum gossypium): a natural biopolymer.

    Science.gov (United States)

    Rastogi, Lori; Beedu, Sashidhar Rao; Kora, Aruna Jyothi

    2015-12-01

    Palladium nanoparticles (Pd NPs) were synthesised by using gum kondagogu (GK), a non-toxic ecofriendly biopolymer. GK acted as both reducing and stabilising agent for the synthesis of Pd NPs. Various reaction parameters, such as concentration of gum, Pd chloride and reaction pH were standardised for the stable synthesis of GK reduced stabilised Pd NPs (GK-Pd NPs). The nanoparticles have been characterised using ultraviolet-visible spectroscopy, transmission electron microscopy and X-ray diffraction. Physical characterisation revealed that the gum synthesised Pd NPs were in the size range of 6.5 ± 2.3 nm and crystallised in face centred cubic (FCC) symmetry. Fourier transform infrared spectroscopy implicated the role of carboxyl, amine and hydroxyl groups in the synthesis. The synthesised Pd NPs were found to be highly stable in nature. The synthesised nanoparticles were found to function as an effective green catalyst (k = 0.182 min⁻¹) in the reduction of 4-nitrophenol by sodium borohydride, which was evident from the colour change of bright yellow (nitrophenolate; λ(max) - 400 nm) to colourless (4-AP; λ(max) - 294 nm) solution. The overall objectives of the current communication were: (i) to synthesize the Pd NPs using a green reducing/capping agent; GK and (ii) to determine the catalytic performance of the synthesised Pd NPs.

  20. Facile and green synthesis of cellulose nanocrystal-supported gold nanoparticles with superior catalytic activity.

    Science.gov (United States)

    Yan, Wei; Chen, Chang; Wang, Ling; Zhang, Dan; Li, Ai-Jun; Yao, Zheng; Shi, Li-Yi

    2016-04-20

    The emphasis of science and technology shifts toward environmentally friendly and sustainable resources and processes. Herein, we report a facile, one-pot and green synthesis of biomaterial-supported gold nanoparticles (AuNPs) with superior catalytic activity. Cellulose nanocrystal (CNC)-supported AuNPs were prepared by heating the aqueous mixture of HAuCl4, CNCs and polyethylene glycol, avoiding toxic chemicals, extreme condition and complicated procedure. The resultant CNC-supported AuNPs exhibited catalytic activities for the reduction of 4-nitrophenol by sodium borohydride. The maximum apparent rate constant reached 1.47×10(-2)s(-1), and the turnover frequency reached 641h(-1). The superior catalytic performance can be ascribed to the large amount of highly dispersed AuNPs with few nanometers in size which are loaded on CNCs. About 90% of the AuNPs are smaller than 10nm, and nearly 60% of the AuNPs are smaller than 5nm. The synthesis is eco-friendly, facile and low-cost, thus has great potential for industrial and medical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Stereocontrolled synthesis of syn-β-Hydroxy-α-amino acids by direct aldolization of pseudoephenamine glycinamide.

    Science.gov (United States)

    Seiple, Ian B; Mercer, Jaron A M; Sussman, Robin J; Zhang, Ziyang; Myers, Andrew G

    2014-04-25

    β-Hydroxy-α-amino acids figure prominently as chiral building blocks in chemical synthesis and serve as precursors to numerous important medicines. Reported herein is a method for the synthesis of β-hydroxy-α-amino acid derivatives by aldolization of pseudoephenamine glycinamide, which can be prepared from pseudoephenamine in a one-flask protocol. Enolization of (R,R)- or (S,S)-pseudoephenamine glycinamide with lithium hexamethyldisilazide in the presence of LiCl followed by addition of an aldehyde or ketone substrate affords aldol addition products that are stereochemically homologous with L- or D-threonine, respectively. These products, which are typically solids, can be obtained in stereoisomerically pure form in yields of 55-98 %, and are readily transformed into β-hydroxy-α-amino acids by mild hydrolysis or into 2-amino-1,3-diols by reduction with sodium borohydride. This new chemistry greatly facilitates the construction of novel antibiotics of several different classes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Direct synthesis and inkjetting of silver nanocrystals toward printed electronics

    Science.gov (United States)

    Jong Lee, Kwi; Jun, Byung Ho; Kim, Tae Hoon; Joung, Jaewoo

    2006-05-01

    Monolayer-protected silver nanoparticles were directly synthesized in a highly concentrated organic phase (>2 M) and then printed into conductive lines on polyimide by a drop-on-demand inkjet printer. The fully organic phase system contains silver nitrate as a silver precursor, n-butylamine as a media dissolving silver salt, dodecanoic acid as a capping molecule, toluene as a solvent, and sodium borohydride as a reducing reagent. Even using only generic chemicals, monodispersed silver nanocrystals with size of 7 nm were easily synthesized at the 100 g scale in a 1 litre reactor. Hydrocarbon monolayer-protected silver nanocrystal showed excellent dispersion stability even at metal content >70 wt%. The silver ink with metal content of 33 wt% had a viscosity of 5.4 cP and surface tension of 25 dyn cm-1. The silver ink was successfully inkjetted on variable substrates and then metallized at 250 °C. The metallized silver patterns exhibited very low specific electrical resistance (6 µΩ cm)

  3. Managing of gas sensing characteristic of a reduced graphene oxide based gas sensor by the change in synthesis condition: A new approach for electronic nose design

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Taher, E-mail: talizadeh@ut.ac.ir [Department of Analytical Chemistry, Faculty of Chemistry, University College of Science, University of Tehran, P.O. Box 14155-6455, Tehran (Iran, Islamic Republic of); Hamedsoltani, Leyla [Department of Applied Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

    2016-11-01

    Natural graphite was oxidized and exfoliated via two different methods, leading to two types of graphene oxide (GO) materials. The obtained materials were reduced by three different reducing agents including: hydrazine hydrate, ascorbic acid and sodium borohydride, giving thus six kinds of reduced graphene oxide (RGO) materials. The obtained materials were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The RGOs were then used to fabricate different gas sensors and their electrical resistances were recorded upon exposing to various volatile organic compounds vapors (VOCs). Gas sensing selectivity of each RGO was significantly affected by the synthesis condition. The RGO-based sensor array was fabricated and its capability for discrimination of seven kinds of VOCs was evaluated, utilizing principal component analysis and cluster analysis methods. Loading plot indicated that the presence of five RGO-based sensors could effectively discriminate the aimed vapors. The electronic nose, containing five kinds of RGOs, was used for the classification of seven kinds of VOCs at their different concentrations. - Highlights: • Two oxidation procedures and three reducing agents were utilized to produce six kinds of RGOs. • The synthesized different RGOs exhibited significantly different sensing behaviors. • Seven kinds of organic vapors were chosen for the evaluation of discrimination power of EN. • Using PCA, it was found that seven of six RFGOs were appropriate number to use in final EN. • The developed EN was capable of properly discrimination of tested vapors.

  4. An analytical method for determination of mercury by cold vapor atomic absorption spectroscopy; Determinazione di mercurio. Metodo per spettrometria di assorbimento atomico a vapori freddi (CV-AAS)

    Energy Technology Data Exchange (ETDEWEB)

    Campanella, L. [Rome Univ. La Sapienza, Rome (Italy); Mastroianni, D.; Capri, S.; Pettine, M. [CNR, Rome (Italy). Ist. di Ricerca sulle Acque; Spezia, S.; Bettinelli, M. [ENEL, Unified Modelling Language, Piacenza (Italy)

    1999-09-01

    An analytical procedure for the determination of total mercury in wastewaters and natural waters is described. Aqueous samples are fast digested with nitric acid by using the microwave-oven technique; the analysis of mercury is then performed by cold vapor atomic absorption spectrometry (CV-AAS) using two possible instrumental apparatus (batch system or flow injection). Sodium borohydride is used as the reducing agent for mercury in solution (Method A). The use of amalgamation traps on gold for the preconcentration of mercury lowers the detection limit of the analyte (Method B). [Italian] Viene descritta una procedura analitica per la determinazione del mercurio totale in acque di scarico e naturali. Il campione acquoso viene sottoposto a mineralizzazione con acido nitrico in forno a microonde e analizzato mediante spettroscopia di assorbimento atomico a vapori freddi (CV-AAS) in due possibili configurazioni strumentali (sistema batch oppure flow injection), utilizzando sodio boro idruro come agente riducente del mercurio (metodo A). L'impiego della trappola di oro per la preconcentrazione del mercurio mediante amalgama consente di determinare l'analita a livelli di pochi ng/L (metodo B).

  5. Ligand-optimized electroless synthesis of silver nanotubes and their activity in the reduction of 4-nitrophenol

    International Nuclear Information System (INIS)

    Muench, Falk; Rauber, Markus; Stegmann, Christian; Lauterbach, Stefan; Kunz, Ulrike; Kleebe, Hans-Joachim; Ensinger, Wolfgang

    2011-01-01

    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 AgNO 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.

  6. Enhanced catalytic hydrogenation activity of Ni/reduced graphene oxide nanocomposite prepared by a solid-state method

    Science.gov (United States)

    Li, Yizhao; Cao, Yali; Jia, Dianzeng

    2018-01-01

    A simple solid-state method has been applied to synthesize Ni/reduced graphene oxide (Ni/rGO) nanocomposite under ambient condition. Ni nanoparticles with size of 10-30 nm supported on reduced graphene oxide (rGO) nanosheets are obtained through one-pot solid-state co-reduction among nickel chloride, graphene oxide, and sodium borohydride. The Ni/rGO nanohybrid shows enhanced catalytic activity toward the reduction of p-nitrophenol (PNP) into p-aminophenol compared with Ni nanoparticles. The results of kinetic research display that the pseudo-first-order rate constant for hydrogenation reaction of PNP with Ni/rGO nanocomposite is 7.66 × 10-3 s-1, which is higher than that of Ni nanoparticles (4.48 × 10-3 s-1). It also presents superior turnover frequency (TOF, 5.36 h-1) and lower activation energy ( E a, 29.65 kJ mol-1) in the hydrogenation of PNP with Ni/rGO nanocomposite. Furthermore, composite catalyst can be magnetically separated and reused for five cycles. The large surface area and high electron transfer property of rGO support are beneficial for good catalytic performance of Ni/rGO nanocomposite. Our study demonstrates a simple approach to fabricate metal-rGO heterogeneous nanostructures with advanced functions.

  7. NiWO4-ZnO-NRGO ternary nanocomposite as an efficient photocatalyst for degradation of methylene blue and reduction of 4-nitro phenol

    Science.gov (United States)

    Sadiq, M. Mohamed Jaffer; Shenoy, U. Sandhya; Bhat, D. Krishna

    2017-10-01

    A novel NiWO4-ZnO-NRGO ternary nanocomposite has been efficiently synthesized by decorating nitrogen doped reduced graphene oxide (NRGO) with zinc oxide and nickel tungstate nanoparticles via a facile microwave irradiation technique and its capability to catalyze photodegradation of methylene blue (MB) dye in aqueous solution and reduction of 4-nitro phenol (4-NP) to 4-amino phenol (4-AP) using sodium borohydride was explored. The as-synthesized nanocomposite was characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) analysis, energy dispersive X-ray (EDX) analysis, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic activity of the as-synthesized nanocomposite estimated through the photodegradation of MB under visible light irradiation showed 9 times improvement over pure NiWO4. It also showed excellent catalytic activity in reduction of 4-NP to 4-AP. The material also showed excellent stability and reusability. The entire study revealed that the novel NiWO4-ZnO-NRGO ternary nanocomposite can act as a promising bifunctional photocatalyst for environmental remediation and industrial application.

  8. Modified multi-wall carbon nanotubes as metal free catalyst for application in H2 production from methanolysis of NaBH4

    Science.gov (United States)

    Sahiner, Nurettin

    2017-10-01

    Multi-walled carbon nanotubes (MWCNT) are modified by acid treatments to obtain MWCNT-COOHs and used as metal free catalyst directly in H2 generation from the methanolysis of sodium borohydride (NaBH4). The chemically modified MWCNT-COOHs are characterized with Fourier Transform Infrared Spectroscopy (FT-IR) and zeta potential measurements. The H2 generation reactions are proceeded at different reaction conditions to determine the optimum reaction parameters such as the concentration of NaBH4 and temperature, the reusability of catalyst, and the regeneration of catalyst. The MWCNT-COOHs are found to be very effective catalyst in comparison to the metal nanoparticle catalyzed H2 generation reactions from the methanolysis of NaBH4. Thus, hydrogen generation rate (HGR) is calculated as 8766 ± 477 mL H2 g-1 min-1 for 500 mM NaBH4 in 20 mL methanol in presence of 50 mg MWCNT-COOH. Furthermore, the activation energy (Ea) for the methanolysis of NaBH4 in presence of MWCNT-COOHs is computed as 20.1 ± 1.4 kJ mol-1, comparable with most of the reported metal nanoparticle based catalyst in the literature.

  9. Spontaneous synthesis of gold nanoparticles on gum arabic-modified iron oxide nanoparticles as a magnetically recoverable nanocatalyst

    Science.gov (United States)

    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

  10. Synthesis of Gold Nanoparticles Using Garcinia Indica Fruit Rind Extract

    Science.gov (United States)

    Krishnaprabha, M.; Pattabi, Manjunatha

    2016-10-01

    This report presents the easily reproducible biosynthesis of gold nanoparticles (AuNPs) at room temperature with extract prepared using three year old dried Garcinia Indica (GI) fruit rind. Due to the presence of two major bioactive compounds garcinol and hydroxy citric acid, rinds of GI fruit exhibit anti-cancer and anti-obesity properties. The quantity of fruit rind extract directed the morphology of the as synthesized particles. The nucleation and growth of AuNPs and catalytic activity are studied using UV-Vis spectroscopy. The crystalline nature of biosynthesized AuNPs is corroborated by X-ray Diffraction techniques. The morphology is studied using field emission scanning electron microscopy (FESEM). Fourier transform infra-red (FTIR) spectroscopy analysis revealed that biomolecules were involved in the synthesis and capping of AuNPs. As the Fermi potential of noble metal NPs becomes more negative, they are used in various electron transfer processes. The AuNPs produced using GI extract showed excellent catalytic activity when used as a catalyst in the reduction of well-known toxic pollutant 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP) in the presence of excess sodium borohydride.

  11. Synthesis, characterization and fabrication of copper nanoparticles in N-isopropylacrylamide based co-polymer microgels for degradation of p-nitrophenol

    Directory of Open Access Journals (Sweden)

    Farooqi Zahoor H.

    2015-03-01

    Full Text Available Poly(N-isopropylacrylamide-co-acrylic acid [P(NIPAM-co-AAc] microgels were synthesized by precipitation polymerization. Copper nanoparticles were successfully fabricated inside the microgels by in-situ reduction of copper ions in an aqueous medium. The microgels were characterized by Fourier Transform Infrared Spectroscopy (FT-IR and Dynamic Light Scattering (DLS. Hydrodynamic radius of P(NIPAM-co-AAc microgel particles increased with an increase in pH in aqueous medium at 25 °C. Copper-poly(N-isopropylacrylamide-co-acrylic acid [Cu-P(NIPAM-co-AAc] hybrid microgels were used as a catalyst for the reduction of 4-nitrophenol (4-NP. Effect of temperature, concentration of sodium borohydride (NaBH4 and catalyst dosage on the value of apparent rate constant (kapp for catalytic reduction of 4-NP in the presence of Cu-P(NIPAM-co-AAc hybrid microgels were investigated by UV-Vis spectrophotometry. It was found that the value of kapp for catalytic reduction of 4-NP in the presence of Cu-P(NIPAM-co-AAc hybrid microgel catalyst increased with an increase in catalyst dosage, temperature and concentration of NaBH4 in aqueous medium. The results were discussed in terms of diffusion of reactants towards catalyst surface and swelling-deswelling of hybrid microgels.

  12. Highly stable noble-metal nanoparticles in tetraalkylphosphonium ionic liquids for in situ catalysis.

    Science.gov (United States)

    Banerjee, Abhinandan; Theron, Robin; Scott, Robert W J

    2012-01-09

    Gold and palladium nanoparticles were prepared by lithium borohydride reduction of the metal salt precursors in tetraalkylphosphonium halide ionic liquids in the absence of any organic solvents or external nanoparticle stabilizers. These colloidal suspensions remained stable and showed no nanoparticle agglomeration over many months. A combination of electrostatic interactions between the coordinatively unsaturated metal nanoparticle surface and the ionic-liquid anions, bolstered by steric protection offered by the bulky alkylated phosphonium cations, is likely to be the reason behind such stabilization. The halide anion strongly absorbs to the nanoparticle surface, leading to exceptional nanoparticle stability in halide ionic liquids; other tetraalkylphosphonium ionic liquids with non-coordinating anions, such as tosylate and hexafluorophosphate, show considerably lower affinities towards the stabilization of nanoparticles. Palladium nanoparticles stabilized in the tetraalkylphosphonium halide ionic liquid were stable, efficient, and recyclable catalysts for a variety of hydrogenation reactions at ambient pressures with sustained activity. Aerial oxidation of the metal nanoparticles occurred over time and was readily reversed by re-reduction of oxidized metal salts. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Poly(N-isopropylacrylamide-co-methacrylic acid microgel stabilized copper nanoparticles for catalytic reduction of nitrobenzene

    Directory of Open Access Journals (Sweden)

    Farooqi Zahoor H.

    2015-09-01

    Full Text Available Poly(N-isopropylacrylamide-co-methacrylic acid microgels [p(NIPAM-co-MAAc] were synthesized by precipitation polymerization of N-isopropylacrylamide and methacrylic acid in aqueous medium. These microgels were characterized by dynamic light scattering and Fourier transform infrared spectroscopy. These microgels were used as micro-reactors for in situ synthesis of copper nanoparticles using sodium borohydride (NaBH4 as reducing agent. The hybrid microgels were used as catalysts for the reduction of nitrobenzene in aqueous media. The reaction was performed with different concentrations of cat­alyst and reducing agent. A linear relationship was found between apparent rate constant (kapp and amount of catalyst. When the amount of catalyst was increased from 0.13 to 0.76 mg/mL then kapp was increased from 0.03 to 0.14 min-1. Activation parameters were also determined by performing reaction at two different temperatures. The catalytic process has been discussed in terms of energy of activation, enthalpy of activation and entropy of activation. The synthesized particles were found to be stable even after 14 weeks and showed catalytic activity for the reduction of nitrobenzene.

  14. Pd-Au/C catalysts with different alloying degrees for ethanol oxidation in alkaline media

    International Nuclear Information System (INIS)

    Qin, Yuan-Hang; Li, Yunfeng; Lv, Ren-Liang; Wang, Tie-Lin; Wang, Wei-Guo; Wang, Cun-Wen

    2014-01-01

    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 OH ads as compared with Pd/C catalyst due to its core-shell structure

  15. High-Efficiency Palladium Nanoparticles Supported on Hydroxypropyl-β-Cyclodextrin Modified Fullerene [60] for Ethanol Oxidation

    International Nuclear Information System (INIS)

    Zhang, Qing; Bai, Zhengyu; Shi, Min; Yang, Lin; Qiao, Jinli; Jiang, Kai

    2015-01-01

    Highlights: • C 60 support provides new ways to develop catalyst materials for its distorted structure. • Pd nanoparticles with uniform size and high dispersion have been successfully assembled on HP-β-CD-C 60 in aqueous solution. • Pd/HP-β-CD-C 60 shows very promising catalytic activity for ethanol oxidation. - Abstract: In this paper, Palladium nanoparticles with uniform size and high dispersion have been successfully assembled on hydroxypropyl-β-Cyclodextrin (HP-β-CD) modified C 60 (abbreviated as HP-β-CD-C 60 ) via a sodium borohydride reduction process. According to the transmission electron microscopy (TEM) measurements, the average particle size of the as-prepared Pd nanoparticles dispersed on HP-β-CD modified C 60 is 2.7 nm. Electrochemical studies reveal that the Pd/HP-β-CD-C 60 modified electrode shows a significantly high electrocatalytic activity, much more negative onset potentials and better stability than electrodes modified by other electrocatalysts for ethanol oxidation, which indicates that it is a better potential candidate for application in a direct ethanol fuel cell (DEFC)

  16. Fabrication and investigation of magnetite nanoparticles with gold shell

    International Nuclear Information System (INIS)

    Semenova, Ekaterina M.; Vorobyova, Svetlana A.; Lesnikovich, Anatoly I.; Fedotova, Julia A.; Bayev, Vadim G.

    2012-01-01

    Highlights: ► Core–shell nanoparticles were prepared by an interphase synthesis. ► The size of Fe 3 O 4 /Au nanoparticles is 12.8 nm with 1.2 nm gold shell. ► Fe 3 O 4 /Au nanoparticles are formed in a mixture with particles of gold and magnetite. - Abstract: A simple room temperature technique of Fe 3 O 4 /Au nanocrystals preparation in two-phase system was reported. The organic phase contains the mixture of the octane-based magnetic fluid and chloroauric acid complex with quaternary ammonium compound. AuCl 4 − was transferred from aqueous solution to octane using N-(2-(didecylamino) ethyl)-N,N-tridecyldecan-1-ammonium iodide as the phase-transfer reagent. The aqueous phase contains the sodium borohydride that was used as a reducing agent. The synthesized core–shell nanoparticles have a particle size of 12.8 nm with a gold shell thickness of approximately 1.2 nm. The principles of interphase synthesis and properties of prepared nanoparticles were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet–visible (UV–vis) and Mössbauer spectroscopies.

  17. 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.

  18. Chelant extraction and REDOX manipulation for mobilization of heavy metals from contaminated soils

    International Nuclear Information System (INIS)

    Brewster, M.D.; Peters, R.W.; Miller, G.A.; Patton, T.L.; Martino, L.E.

    1994-01-01

    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

  19. 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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Potential of hot water extraction of birch wood to produce high-purity dissolving pulp after alkaline pulping.

    Science.gov (United States)

    Borrega, Marc; Tolonen, Lasse K; Bardot, Fanny; Testova, Lidia; Sixta, Herbert

    2013-05-01

    The potential of hot water extraction of birch wood to produce highly purified dissolving pulp in a subsequent soda-anthraquinone pulping process was evaluated. After intermediate extraction intensities, pulps with low xylan content (3-5%) and high cellulose yield were successfully produced. Increasing extraction intensity further decreased the xylan content in pulp. However, below a xylan content of 3%, the cellulose yield dramatically decreased. This is believed to be due to cleavage of glycosidic bonds in cellulose during severe hot water extractions, followed by peeling reactions during alkaline pulping. Addition of sodium borohydride as well as increased anthraquinone concentration in the pulping liquor increased the cellulose yield, but had no clear effects on pulp purity and viscosity. The low intrinsic viscosity of pulps produced after severe extraction intensities and soda-anthraquinone pulping corresponded to the viscosity at the leveling-off degree of polymerization, suggesting that nearly all amorphous cellulose had been degraded. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. A DFT study of Cu nanoparticles adsorbed on defective graphene

    International Nuclear Information System (INIS)

    García-Rodríguez, D.E.; Mendoza-Huizar, L.H.; Díaz, C.

    2017-01-01

    Highlights: • Cu n supported on graphene may be a promising electrode material for DBFC's cells. • Cu n /graphene interaction is rather local and size independent. • Cu 13 anchors strongly to defects in graphene, while keeping its gas-phase properties. - Abstract: Metal nanoparticles adsorbed on graphene are systems of interest for processes relative to catalytic reactions and alternative energy production. Graphene decorated with Cu-nanoparticles, in particular, could be a good alternative material for electrodes in direct borohydride fuel cells. However our knowledge of this system is still very limited. Based on density functional theory, we have analyzed the interaction of Cu n nanoparticles (n = 4, 5, 6, 7, 13) with pristine and defective-graphene. We have considered two types of defects, a single vacancy (SV), and an extended lineal structural defect (ELSD), formed by heptagon-pentagon pairs. Our analysis has revealed the covalent character of the Cu n -graphene interaction for pristine- and ELSD-graphene, and a more ionic-like interaction for SV-graphene. Furthermore, our analysis shows that the interaction between the nanoparticles and the graphene is rather local, i.e., only the nanoparticle atoms close to the contact region are involved in the interaction, being the electronic contact region much higher for defective-graphene than for pristine-graphene. Thus, the higher the particle the lower its average electronic and structural distortion.

  2. Effect of Solvent Type and Viscosity on Modified Polyol Synthesis of Sn Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chee, Sang-Soo; Kim, Ji Hwan; Lee, Jong-Hyun [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2015-04-15

    We report on the effect of solvent type on the synthesis of Sn nanoparticles via a modified polyol method at room temperature in an ambient atmosphere. In the synthesis, tin (II) 2-ethylhexanoate, sodium borohydride (NaBH{sub 4}), and polyvinylpyrrolidone (PVP) were used as a precursor, reducing agent, and capping molecule, respectively. Transmission electron microscopy confirmed by that the Sn nanoparticles obtained in 1,5-pentanediol were smaller (9.2 nm) than 10 nm for an average diameter and had a narrow size distribution. We also observed that the average diameter of Sn nanoparticles obtained in 1,5-pentanediol increased slightly with a decreasing PVP molecular weight. The result can explain the synthesis mechanism in which Sn ions are not only preferential in forming a complex with the PVP but also preferentially reduced in a solvent, and the movement of reduced particles is influenced by the PVP. Consequently, an increase in PVP molecular weight may more effectively inhibit coalescence between nanoparticles, which are surrounded by a longer molecular chain and are highly viscous in the synthesis solution, all of which finally results in a decrease in the average particle size. On the basis of Fourier-transform infrared spectroscopy result, we demonstrated that the PVP on the Sn surface could be removed using an acetone/methanol mixed solvent.

  3. Investigation of oxygen reduction and methanol oxidation reaction activity of PtAu nano-alloy on surface modified porous hybrid nanocarbon supports

    Science.gov (United States)

    Parambath Vinayan, Bhaghavathi; Nagar, Rupali; Ramaprabhu, Sundara

    2016-09-01

    We investigate the electrocatalytic activity of PtAu alloy nanoparticles supported on various chemically modified carbon morphologies towards oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The surface-modification of graphene nanosheets (f-G), multi-walled carbon nanotubes (f-MWNTs) and (graphene nanosheets-carbon nanotubes) hybrid support (f-G-MWNTs) were carried out by soft functionalization method using a cationic polyelectrolyte poly-(diallyldimethyl ammonium chloride). The Pt and PtAu alloy nanoparticles were dispersed over chemically modified carbon supports by sodium-borohydride assisted modified polyol reduction method. The electrochemical performance of all electrocatalysts were studied by half- and full-cell proton exchange membrane fuel cell (PEMFC) measurements and PtAu/f-G-MWNTs catalyst comparatively yielded the best catalytic performance. PEMFC full cell measurements of PtAu/f-G-MWNTs cathode electrocatalyst yield a maximum power density of 319 mW cm-2 at 60 °C without any back pressure,which is 2.1 times higher than that of cathode electrocatalyst Pt on graphene support. The high ORR and MOR activity of PtAu/f-G-MWNTs electrocatalyst is due to the alloying effect and inherent beneficial properties of porous hybrid nanocarbon support.

  4. Hydrophilic silver nanoparticles with tunable optical properties: application for the detection of heavy metals in water.

    Science.gov (United States)

    Prosposito, Paolo; Mochi, Federico; Ciotta, Erica; Casalboni, Mauro; De Matteis, Fabio; Venditti, Iole; Fontana, Laura; Testa, Giovanna; Fratoddi, Ilaria

    2016-01-01

    Due their excellent chemo-physical properties and ability to exhibit surface plasmon resonance, silver nanoparticles (AgNPs) have become a material of choice in various applications, such as nanosensors, electronic devices, nanobiotechnology and nanomedicine. In particular, from the environmental monitoring perspective, sensors based on silver nanoparticles are in great demand because of their antibacterial and inexpensive synthetic method. In the present study, we synthesized AgNPs in water phase using silver nitrate as precursor molecules, hydrophilic thiol (3-mercapto-1-propanesulfonic acid sodium salt, 3MPS) and sodium borohydride as capping and reducing agents, respectively. The AgNPs were characterized using techniques such as surface plasmon resonance (SPR) spectroscopy, dynamic light scattering (DLS), zeta potential (ζ-potential) measurements and scanning tunneling microscopy (STM). Further, to demonstrate the environmental application of our AgNPs, we also applied them for heavy metal sensing by detecting visible color modification due to SPR spectral changes. We found that these negatively charged AgNPs show good response to nickel (II) and presented good sensibility properties for the detection of low amount of ions in water in the working range of 1.0-0.1 ppm.

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

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lei, E-mail: xulei_kmust@aliyun.com [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Mechanical Engineering, University of Washington, Seattle 98195 (United States); Peng, Jinhui [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Srinivasakannan, C. [Chemical Engineering Program, The petroleum Institute, Abu Dhabi, P.O. Box 253 (United Arab Emirates); Chen, Guo [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Shen, Amy Q., E-mail: amy.shen@oist.jp [Mechanical Engineering, University of Washington, Seattle 98195 (United States); Micro/Bio/Nanofluidics Unit, Okinawa Institute of Technology Graduate University, Okinawa (Japan)

    2015-11-15

    Highlights: • The copper nanocolloidal were synthesized in a T-shaped microreactor at room temperature. • The morphology of copper nanocolloidal are spherical, and with good size distribution. • The mean particle diameter increased with decreases the NaBH{sub 4} molar concentration. • With increasing particle size, the more obvious localized surface plasmon resonance absorption. - Abstract: The copper (Cu) nanocolloids were prepared by sodium borohydride (NaBH{sub 4}) reduction of metal salt solutions in a T-shaped microreactor at room temperature. The influence of NaBH{sub 4} 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 NaBH{sub 4} molar concentrations. The maximum mean diameter (4.25 nm) occurred at the CuSO{sub 4}/NaBH{sub 4} molar concentration ratio of 1:2.

  6. 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.

  7. [The disulfide bridges of the trypsin-kallikrein inhibitor K from snails (Helix pomatia). Thermal inactivation and proteolysis by thermolysin (author's transl)].

    Science.gov (United States)

    Dietl, T; Tschesche, H

    1976-02-01

    Isoinhibitor K is the main component of the complex mixture of isoinhibitors of broad specificity secreted into the mucus by the Roman snail (Helix pomatia). The disulfide pairing was determined after the amino acid sequence had been elucidated. Two cystine-containing peptides with the disulfide bridges Cys32-Cys53 and Cys32-Cys53 plus Cys7-Cys57 were obtained after thermolytic hydrolysis of the native inhibitor at 80 degrees C and chromatographic separation of the peptides using SE-Sephadex. The Cys16-Cys40 disulfide bridge could be reduced selectively by sodium borohydride with no loss in biological activity. This property and the covalent structure correspond to that of the intracellular inhibitor from bovine organs, which is largely homologous in its amino acid sequence to the secretory inhibitor from the snail. The complete covalent structure of isoinhibitor K will be presented. The snail inhibitor is less stable against proteolytic inactivation by thermolysin and against thermal denaturation at pH 8.0 than the inhibitor from bovine organs (Kunitz inhibitor).

  8. Reaction of 11 C-benzoyl chlorides with metalloid reagents: 11 C-labeling of benzyl alcohols, benzaldehydes, and phenyl ketones from [11 C]CO.

    Science.gov (United States)

    Roslin, Sara; Dahl, Kenneth; Nordeman, Patrik

    2018-01-26

    In this article, we describe the carbon-11 ( 11 C, t 1/2  = 20.4 minutes) labeling of benzyl alcohols, benzaldehydes, and ketones using an efficient 2-step synthesis in which 11 C-carbon monoxide is used in an initial palladium-mediated reaction to produce 11 C-benzoyl chloride as a key intermediate. In the second step, the obtained 11 C-benzoyl chloride is further treated with a metalloid reagent to furnish the final 11 C-labeled product. Benzyl alcohols were obtained in moderated to high non-isolated radiochemical yields (RCY, 35%-90%) with lithium aluminum hydride or lithium aluminum deuteride as metalloid reagent. Changing the metalloid reagent to either tributyltin hydride or sodium borohydride, allowed for the reliable syntheses of 11 C-benzaldehydes in RCYs ranging from 58% to 95%. Finally, sodium tetraphenylborate were utilized to obtain 11 C-phenyl ketones in high RCYs (77%-95%). The developed method provides a new and efficient route to 3 different classes of compounds starting from aryl iodides or aryl bromides. Copyright © 2018 John Wiley & Sons, Ltd.

  9. Co3O4/CoP composite hollow polyhedron: A superior catalyst with dramatic efficiency and stability for the room temperature reduction of 4-nitrophenol

    Science.gov (United States)

    Liu, Xing; Li, Xiangqing; Qin, Lixia; Mu, Jin; Kang, Shi-Zhao

    2018-03-01

    In the present work, Co3O4/CoP composite hollow polyhedrons were prepared and characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and N2 adsorption-desorption isotherms. Then, the catalytic activity of the as-prepared Co3O4/CoP hollow polyhedrons was evaluated for the borohydride-assisted reduction of 4-nitrophenol at room temperature. The results indicate that the as-prepared Co3O4/CoP hollow polyhedrons are an efficient recyclable catalyst for the reduction of 4-nitrophenol. When the 4-nitrophenol initial concentration is 1.0 × 10-4 mol L-1 (100 mL), almost 100% 4-nitrophenol can be reduced within 3 min in the presence of the Co3O4/CoP hollow polyhedrons. The apparent rate constant of the 4-nitrophenol reduction is 1.61 min-1 at room temperature, and the activity factor is about 5.37 × 104 mL min-1 g-1, which is almost two times higher than that over Ag nanoparticles. Finally, the catalytic mechanism was preliminarily discussed. It is found that CoP plays an important role in the catalytic process. Here, CoP serves as active sites, which leads to efficient formation of hydrogen atoms from BH4- and fast electron transfer.

  10. Synthesis, characterization and magnetic properties of nanocrystalline FexNi80-xCo20 ternary alloys

    Science.gov (United States)

    Dalavi, Shankar B.; Theerthagiri, J.; Raja, M. Manivel; Panda, R. N.

    2013-10-01

    Fe-Ni-Co alloys of various compositions (FexNi80-xCo20,x=20-50) were synthesized by using a sodium borohydride reduction route. The phase purity and crystallite size was ascertained by using powder X-ray diffraction (XRD). The alloys crystallize in the face centered cubic (fcc) structure with lattice parameters, a=3.546-3.558 Å. The XRD line broadening indicates the fine particle nature of the materials. The estimated crystallite sizes were found to be 27.5, 27, 24, and 22.8 nm for x=20, 30, 40, and 50; alloys respectively. Scanning electron micrograph studies indicates particle sizes to be in the range of 83-60 nm for Fe-Ni-Co alloys. The values of saturation magnetization for FexNi80-xCo20 are found to be in the range of 54.3-41.2 emu/g and are significantly lower than the bulk values (175-180 emu/g). The coercivity decreases from 170 to 122 Oe with decrease in Fe content. The observed magnetic behavior has been explained on the basis of size, surface effects, spin canting and the presence of superparamagnetic fractions in the ultrafine materials.

  11. Boronic acid recognition of non-interacting carbohydrates for biomedical applications: increasing fluorescence signals of minimally interacting aldoses and sucralose.

    Science.gov (United States)

    Resendez, Angel; Halim, Md Abdul; Singh, Jasmeet; Webb, Dominic-Luc; Singaram, Bakthan

    2017-11-22

    To address carbohydrates that are commonly used in biomedical applications with low binding affinities for boronic acid based detection systems, two chemical modification methods were utilized to increase sensitivity. Modified carbohydrates were analyzed using a two component fluorescent probe based on boronic acid-appended viologen-HPTS (4,4'-o-BBV). Carbohydrates normally giving poor signals (fucose, l-rhamnose, xylose) were subjected to sodium borohydride (NaBH 4 ) reduction in ambient conditions for 1 h yielding the corresponding sugar alcohols from fucose, l-rhamnose and xylose in essentially quantitative yields. Compared to original aldoses, apparent binding affinities were increased 4-25-fold. The chlorinated sweetener and colon permeability marker sucralose (Splenda), otherwise undetectable by boronic acids, was dechlorinated to a detectable derivative by reactive oxygen and hydroxide intermediates by the Fenton reaction or by H 2 O 2 and UV light. This method is specific to sucralose as other common sugars, such as sucrose, do not contain any carbon-chlorine bonds. Significant fluorescence response was obtained for chemically modified sucralose with the 4,4'-o-BBV-HPTS probe system. This proof of principle can be applied to biomedical applications, such as gut permeability, malabsorption, etc.

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

    Energy Technology Data Exchange (ETDEWEB)

    Song, Cunfeng [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chang, Ying; Cheng, Ling; Xu, Yiting [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Chen, Xiaoling, E-mail: tinachen0628@163.com [Department of Endodontics, Xiamen Stomatology Hospital, Teaching Hospital of Fujian Medical University, Xiamen 361003 (China); Zhang, Long; Zhong, Lina [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Dai, Lizong, E-mail: lzdai@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)

    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. - Highlights: • A new type of antibacterial agent (PSA/Ag-NPs nanocomposites) was synthesized. • The antibacterial activity against S. aureus and E. coli was studied. • Inhibition zone, MIC, MBC, and bactericidal kinetics were evaluated. • PSA/Ag-NPs nanocomposites showed excellent antibacterial activity.

  13. Green synthesis of iron nanoparticles by various tea extracts: Comparative study of the reactivity

    Science.gov (United States)

    Huang, Lanlan; Weng, Xiulan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

    2014-09-01

    Iron nanoparticles (Fe NPs) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. To address these issues, Fe NPs were synthesized using green methods based on tea extracts, including green, oolong and black teas. The best method for degrading malachite green (MG) was Fe NPs synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synthesis of Fe NPs. These characteristics were confirmed by a scanning electron microscope (SEM), UV-visible (UV-vis) and specific surface area (BET). To understand the formation of Fe NPs using various tea extracts, the synthesized Fe NPs were characterized by SEM, X-ray energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD). What emerged were different sizes and concentrations of Fe NPs being synthesized by tea extracts, leading to various degradations of MG. Furthermore, kinetics for the degradation of MG using these Fe NPs fitted well to the pseudo first-order reaction kinetics model with more than 20 kJ/mol activation energy, suggesting a chemically diffusion-controlled reaction. The degradation mechanism using these Fe NPs included adsorption of MG to Fe NPs, oxidation of iron, and cleaving the bond that was connected to the benzene ring.

  14. A biomimetic synthesis of stable gold nanoparticles derived from aqueous extract of Foeniculum vulgare seeds and evaluation of their catalytic activity

    Science.gov (United States)

    Choudhary, Manoj Kumar; Kataria, Jyoti; Sharma, Shweta

    2017-10-01

    A facile biomimetic approach for the synthesis of gold nanoparticles (AuNPs) using aqueous extract of fennel ( Foeniculum vulgare) seeds have been reported in this article. The seeds of F. vulgare are rich in various plant secondary metabolites (phytochemicals) such as polyphenolic acids, flavonoids, and saponins. The phytochemicals of F. vulgare seeds play dual role of reducing and stabilizing agents. The formation of gold nanoparticles was evidenced from the appearance of intense purple color at room temperature with λ max around 550 nm in the UV-Vis absorption spectra. The stable AuNPs were further characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM) analysis. The synthesized nanoparticles were observed to be polydispersed, spherical and ranged from 10 to 30 nm with an average size of 20 ± 2 nm, as obtained from TEM images. The catalytic activity of gold nanoparticles was investigated by studying the reduction of anthropogenic dyes such as methylene blue (MB) and rhodamine B (Rh-B) with sodium borohydride. Results showed the possible applications of biogenic AuNPs in environment related problems.

  15. Topological disposition of the sequences -QRKIVE- and -KETYY in native (Na+ + K+)-ATPase

    International Nuclear Information System (INIS)

    Bayer, R.

    1990-01-01

    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 [ 3 H]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

  16. Synthesis and characterization of silver/talc nanocomposites using the wet chemical reduction method

    Directory of Open Access Journals (Sweden)

    Kamyar Shameli

    2010-09-01

    Full Text Available Kamyar Shameli1, Mansor Bin Ahmad1, Wan Zin Wan Yunus1, Nor Azowa Ibrahim1, Majid Darroudi21Department of Chemistry, Faculty of Science, 2Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, Selangor, MalaysiaAbstract: In this study, silver nanoparticles (Ag-NPs were synthesized using the wet chemical reduction method on the external surface layer of talc mineral as a solid support. Silver nitrate and sodium borohydride were used as the silver precursor and reducing agent in talc. The talc was suspended in aqueous AgNO3 solution. After the absorption of Ag+ on the surface, the ions were reduced with NaBH4. The interlamellar space limits were without many changes (ds = 9.34–9.19 Aº; therefore, Ag-NPs formed on the exterior surface of talc, with dave = 7.60–13.11 nm in diameter. The properties of Ag/talc nanocomposites (Ag/talc-NCs and the diameters of the Ag-NPs prepared in this way depended on the primary AgNO3 concentration. The prepared Ag-NPs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared. These Ag/talc-NCs may have potential applications in the chemical and biological industries.Keywords: nanocomposites, silver nanoparticles, talc, powder X-ray diffraction, scanning electron microscopy

  17. Synthesis and Characterization of Ti-Phenyl at SiO2 Core-Shell Nanoparticles Catalyst

    International Nuclear Information System (INIS)

    Syamsi Aini; Jon Efendi; Syamsi Aini; Jon Efendi

    2012-01-01

    This study highlights the potential use of Ti-Phenyl at SiO 2 core-shell nanoparticles as heterogeneous catalysis in oxidation reaction. The Ti-Phenyl at SiO 2 was synthesized by reduction of TiCl 4 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 SiO 2 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 SiO 2 was in the range of 40 to 100 nm with its core composed with an agglomeration of Ti-Phenyl. The Ti-Phenyl at SiO 2 was active as a catalyst in the liquid phase epoxidation of 1-octene with aqueous hydrogen peroxide as an oxidant. (author)

  18. Biosynthesis of ascites sialoglycoprotein-1, the major O-linked glycoprotein of 13762 rat mammary adenocarcinoma ascites cells

    International Nuclear Information System (INIS)

    Spielman, J.

    1987-01-01

    The present studies were undertaken to determine the timing of the major events in biosynthesis, and to characterize the contributions of chain initiation and elongation in maturation of the glycoprotein. Initiation of the earliest O-linked chains was detected by analysis of conversion of 3 H-thr to 3 H 2-aminobutyrate following mild alkaline borohydride elimination of O-linked sugars from peanut lectin-precipitated ASGP-1. Initiation was detected within 5 min of translation; amino sugar analysis of GlcNH 2 -labeled, trypsinized cells also showed that GalNAc was added as late as 5 min prior to arrival of ASGP-1 at the cell surface. Thus initiation occurs throughout biosynthesis. Maturation of the glycoprotein from a lightly-glycosylated immature form to the heavily-glycosylated mature from involved both continued initiation of new chains and chain elongation, and occurred with a half-time of about 30 min. Analysis of labeled ASGP-1 released from the cell surface by trypsinization showed that although some newly-synthesized ASGP-1 reached the cell surface within 70-80 min of protein synthesis, the half-time for appearance of mature glycoprotein was in excess of 4 hr, indicating that most molecules reside in an intracellular compartment(s) for a considerable time

  19. Advanced shield development for a fission surface power system for the lunar surface

    International Nuclear Information System (INIS)

    Craft, A.E.; Silver, I.J.; Clark, C.M.; Howe, S.D.; King, J.C.

    2011-01-01

    A nuclear reactor power system such as the affordable fission surface power system enables a potential outpost on the moon. A radiation shield must be included in the reactor system to reduce the otherwise excessive dose to the astronauts and other vital system components. The radiation shield is typically the most massive component of a space reactor system, and thus must be optimized to reduce mass asmuchas possible while still providing the required protection.Various shield options for an on-lander reactor system are examined for outpost distances of 400m and 1 km from the reactor. Also investigated is the resulting mass savings from the use of a high performance cermet fuel. A thermal analysis is performed to determine the thermal behaviours of radiation shields using borated water. For an outpost located 1000m from the core, a tetramethylammonium borohydride shield is the lightest (5148.4 kg), followed by a trilayer shield (boron carbide-tungsten-borated water; 5832.3 kg), and finally a borated water shield (6020.7 kg). In all of the final design cases, the temperature of the borated water remains below 400 K.

  20. Method of preparing Ru-immobilized polymer-supported catalyst for hydrogen generation from NaBH{sub 4} solution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ching-Wen; Chen, Chuh-Yung; Huang, Yao-Hui [Department of Chemical Engineering, National Cheng Kung University, No.1, University Road, Tainan City 70101 (China)

    2009-03-15

    A method of preparing a polymer-supported catalyst for hydrogen generation is introduced in this article. This polymer-supported catalyst is the structure of ruthenium (Ru) nanoparticle immobilized on a monodisperse polystyrene (PSt) microsphere. The diameter of the Ru nanoparticle is around 16 nm, and the diameter of the PSt microsphere is 2.65 um. This preparation method is accomplished by two unique techniques: one is sodium lauryl sulfate/sodium formaldehyde sulfoxylate (SLS/SFS) interface-initiated system, the other is 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester (GMA-IDA) chelating monomer. By taking advantage of these two techniques, Ru{sup 3+} ion will be chelated and then reduced to Ru{sup (0)} nanoparticle over PSt surface predominantly. The hydrolysis of alkaline sodium borohydride (NaBH{sub 4}) solution catalyzed by this Ru-immobilized polymer-supported catalyst is also examined in this article. It reveals that the hydrogen generation rate is 215.9 ml/min g-cat. in a diluted solution containing 1 wt.% NaBH{sub 4} and 1 wt.% NaOH, and this Ru-immobilized polymer-supported catalyst could be recycled during the reaction. (author)

  1. [Non-nascent hydrogen mechanism of plumbane generation].

    Science.gov (United States)

    Zou, Yan; Jin, Fu-xia; Chen, Zhi-jiang; Qiu, De-ren; Yang, Peng-yuan

    2005-10-01

    The mechanism of plumbane generation in dichromate system was studied via investigation of the relationship between the plumbane yield and the molar number of the reactants. A flow injection hydride generator was used in the study. Reactant moler number was calculated by the injected volume and the reactant concentration, and the plumbane yield was measured via an AAS spectrometer equipped with an electrothermal quartz tube atomizer. Experimental results show that the acid was first used for the neutralization of NaOH and successively participated in the redox reaction of borohydride with dichromate with a constant molar ratio of 9.95 +/- 0.42 (expressed in terms of mean +/- standard deviation). At the same time, plumbane generation was displayed as synchronously taking place with the redox reaction, and the yield increased with the increase of acid. The mechanism of plumbane generation was thus deduced as an induced reaction or a catalytic reaction by the redox reaction. Up to this end, the non-nascent hydrogen mechanism of hydride generation has been verified for all the IVA elements.

  2. Leaching and antimicrobial properties of silver nanoparticles loaded onto natural zeolite clinoptilolite by ion exchange and wet impregnation.

    Science.gov (United States)

    Missengue, Roland N M; Musyoka, Nicholas M; Madzivire, Godfrey; Babajide, Omotola; Fatoba, Ojo O; Tuffin, Marla; Petrik, Leslie F

    2016-01-28

    This study aimed to compare the leaching and antimicrobial properties of silver that was loaded onto the natural zeolite clinoptilolite by ion exchange and wet impregnation. Silver ions were reduced using sodium borohydride (NaBH 4 ). The leaching of silver from the prepared silver-clinoptilolite (Ag-EHC) nanocomposite samples and their antimicrobial activity on Escherichia coli Epi 300 were investigated. It was observed that the percentage of silver loaded onto EHC depended on the loading procedure and the concentration of silver precursor used. Up to 87% of silver was loaded onto EHC by wet impregnation. The size of synthesized silver nanoparticles varied between 8.71-72.67 nm and 7.93-73.91 nm when silver was loaded by ion exchange and wet impregnation, respectively. The antimicrobial activity of the prepared nanocomposite samples was related to the concentration of silver precursor used, the leaching rate and the size of silver nanoparticles obtained after reduction. However, only in the case of the nanocomposite sample (Ag-WEHC) obtained after loading 43.80 ± 1.90 µg of Ag per gram zeolite through wet impregnation was the leaching rate lower than 0.1 mg L -1 limit recommended by WHO, with an acceptable microbial killing effect.

  3. Sodium triacetoxyborotritide: its preparation and use

    International Nuclear Information System (INIS)

    Morimoto, H.; Williams, P.G.; Than, C.; Chehade, K.; Spielman, P.

    1997-01-01

    Full text: Tritide reducing agents provide attractive approaches for the preparation of tritiated molecules of high specific activity. During the last decade we have demonstrated the synthesis and use of fully tritiated highly reactive tritide reagents such as lithium triethylborotritide. Lithium aluminium tritide and borane. Recently, the biological molecules of interest have become more complex and the appropriate labelling reagents have become more selective and sophisticated. Sodium triacetoxyborohydride is a very mild and highly selective reducing agent, capable of reducing aldehydes selectively in the presence of ketones. It also reduces indole double bonds, acid chlorides and lactones. It is the reagent of choice for the reductive amination of aldehydes, and saturated aliphatic ketones with primary and secondary amines. Over the past year, we have developed simple, convenient and efficient methods for the labelling of metal borohydrides by exchange with tritium gas. Direct treatment of NaBT 4 with glacial acetic under mild conditions produces sodium triacetoxyborotritide. This reagent was characterized by proton, tritium, and boron NMR spectroscopy. Its utility was demonstrated by its ability to reduce an aldehyde in the presence of a ketone, and by a reductive amination of farnesal acetate and aniline

  4. Synthesis, Characterization and Reactivity of Nanostructured Zero-Valent Iron Particles for Degradation of Azo Dyes

    Science.gov (United States)

    Mikhailov, Ivan; Levina, Vera; Leybo, Denis; Masov, Vsevolod; Tagirov, Marat; Kuznetsov, Denis

    Nanostructured zero-valent iron (NSZVI) particles were synthesized by the method of ferric ion reduction with sodium borohydride with subsequent drying and passivation at room temperature in technical grade nitrogen. The obtained sample was characterized by means of X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering studies. The prepared NSZVI particles represent 100-200nm aggregates, which consist of 20-30nm iron nanoparticles in zero-valent oxidation state covered by thin oxide shell. The reactivity of the NSZVI sample, as the removal efficiency of refractory azo dyes, was investigated in this study. Two azo dye compounds, namely, orange G and methyl orange, are commonly detected in waste water of textile production. Experimental variables such as NSZVI dosage, initial dye concentration and solution pH were investigated. The kinetic rates of degradation of both dyes by NSZVI increased with the decrease of solution pH from 10 to 3 and with the increase of NSZVI dosage, but decreased with the increase of initial dye concentration. The removal efficiencies achieved for both orange G and methyl orange were higher than 90% after 80min of treatment.

  5. High catalytic activity of monometallic Ag, Cu nanostructures in the degradation of acid blue 113 dye: an electron relay effect

    Science.gov (United States)

    Udayabhaskar, R.; Mangalaraja, R. V.; Pandiyarajan, T.; Karthikeyan, B.; Mansilla, Héctor D.

    2017-09-01

    This report discusses the observed faster decoloration of an azo dye with an enhanced degradation rate constant achieved using metal nanostructures as a catalyst. Silver and copper nanostructures were synthesized by reducing the corresponding nitrate salts using hydrazine and hexamethylenetetramine (HMTA) in sodium hydroxide (NaOH) solution. The influence of HMTA was clearly evident from the scanning electron microscopy (SEM) images; with increasing concentration it caused agglomeration and the formation of net-like nanostructures. An x-ray diffraction study confirmed the formation of monometallic Ag and Cu nanostructures. The prepared nanostructures exhibited dipole and multipole surface plasmon resonance-related optical absorption bands which were size and shape dependent. The degradation of the azo dye acid blue 113 (AB113) in the presence of sodium borohydride (NaBH4) was taken as model system for studying the catalytic activity of the metal nanostructures. From the optical absorption spectral studies of dye degradation it was observed that the rate constant (k) was of the order of k Cu   >  k Ag   >  k no catalyst. From the dye degradation studies a high catalytic activity was observed for Cu nanostructures with a rate constant of 20.93  ×  10-4 s-1.

  6. Synthesis of positively charged hybrid PHMB-stabilized silver nanoparticles: the search for a new type of active substances used in plant protection products

    Science.gov (United States)

    Krutyakov, Yurii A.; Kudrinsky, Alexey A.; Gusev, Alexander A.; Zakharova, Olga V.; Klimov, Alexey I.; Yapryntsev, Alexey D.; Zherebin, Pavel M.; Shapoval, Olga A.; Lisichkin, Georgii V.

    2017-07-01

    Modern agriculture calls for a decrease in pesticide application, particularly in order to decrease the negative impact on the environment. Therefore the development of new active substances and plant protection products (PPP) to minimize the chemical load on ecosystems is a very important problem. Substances based on silver nanoparticles are a promising solution of this problem because of the fact that in correct doses such products significantly increase yields and decrease crop diseases while displaying low toxicity to humans and animals. In this paper we for the first time propose application of polymeric guanidine compounds with varying chain lengths (from 10 to 130 elementary links) for the design and synthesis of modified silver nanoparticles to be used as the basis of a new generation of PPP. Colloidal solutions of nanocrystalline silver containing 0.5 g l-1 of silver and 0.01-0.4 g l-1 of polyhexamethylene biguanide hydrochloride (PHMB) were obtained by reduction of silver nitrate with sodium borohydride in the presence of PHMB. The field experiment has shown that silver-containing solutions have a positive effect on agronomic properties of potato, wheat and apple. Also the increase in activity of such antioxidant system enzymes as peroxidase and catalase in the tissues of plants treated with nanosilver has been registered.

  7. Synthesis of [5-14C]pentostatin, an antileukemic agent and potent adenosine deaminase inhibitor

    International Nuclear Information System (INIS)

    Woo, P.W.K.; Lee, H.T.

    1990-01-01

    Reaction of triethyl ortho[ 14 C]formate (2) with 2-amino-1-(5-amino-1H-imidazol-4-yl)ethanone dihydrochloride (1) in the presence of molecular sieves 4A gave 6,7-dihydro[5- 14 C]imidazo[4,5-d]{1,3]diazepin-8(3H)-one hydrochloride monodimethyl sulfoxide (3) (radiochemical yield, 60%). The latter was persilylated with bis(trimethylsilyl)trifluroacetamide (4) and glycosylated with 2-deoxy-3,5-di-0-p-toluoyl-α-D-erythro-pentufuranosyl chloride (6) to give a mixture from which the 3-N-β-glycosylated product 8 was isolated by chromatography and crystallization (13%). Deprotective saponification with methanolic sodium methoxide and subsequent sodium borohydride reduction of the 8-keto function gave a (R,S)-mixture from which the desired (R)-isomer, [5- 14 C]pentostatin (11), was isolated by preparative HPLC over a C18 column, desalting with Diaion-HP20, and subsequent crystallization (39%). (author)

  8. 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.

  9. 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)

  10. 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.

  11. Effect of pH, temperature, humic acid and coexisting anions on reduction of Cr(Ⅵ) in the soil leachate by nZVI/Ni bimetal material.

    Science.gov (United States)

    Zhu, Fang; Li, Luwei; Ren, Wentao; Deng, Xiaoqiang; Liu, Tao

    2017-08-01

    Nano zero valent iron/Ni bimetal materials (nZVI/Ni) were prepared by borohydride reduction method to remediate toxic Cr(Ⅵ) contaminated in soil leachate. nZVI/Ni was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). Different factors including pH value of soil leachate, reaction time, temperature, humic acid and coexisting anions (SO 4 2- , NO 3 - , HCO 3 - , CO 3 2- ) were studied to analyze the reduction rate. Results showed that the reduction rate of Cr(Ⅵ) could reach 99.84% under the condition of pH of 5 and temperature of 303 K. pH values and temperature of soil leachate had a significant effect on the reduction efficiency, while humic acid had inhibition effect for the reduction reaction. SO 4 2- , HCO 3 - and CO 3 2- had inhibition effect for reduction rate, while NO 3 - barely influenced the reduction process of nZVI/Ni. Moreover, Langumir-Hinshelwood first order kinetic model was studied and could describe the reduction process well. The thermodynamic studies indicated that the reaction process was endothermic and spontaneous. Activation energy was 143.80 kJ mol -1 , showing that the reaction occurred easily. Therefore, the study provides an idea for nZVI/Ni further research and practical application of nZVI/Ni in soil remediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Stereoretentive formylation of (S)-proline

    DEFF Research Database (Denmark)

    Temizsoy, Mehmet; Sethi, Waqas; Reinholdt, Anders

    2015-01-01

    In a Vilsmeier-Haack-type formylation reaction the α-(dihydroxymethyl)-(S)-prolinato complex (+)578-p-[Co(tren){(RC,SN)-Pro[CH(OH)2]O}]Cl2·2H2O (22) was produced stereoselectively (85% ee) from the (S)-prolinato complex, (+)578-p-[Co(tren){(SC,SN)-ProO}]2(H3O)2(HOEt2)(O3SCF3)7 (18). Similar...... reaction of the (S)-alaninato complex, (-)578-p-[Co(tren)(S-AlaO)](H3O)(O3SCF3)3 (13), produced the racemate, rac-p-[Co(tren)(Ala{CH(OH)2}O)]SO4·2H2O (17). The contrasting stereochemical outcomes of the formylation reaction with 18versus13 were ascribed to the stereogenic character of the coordinated sec......, constitutes a novel application of the concept of Self-Regeneration of Stereocentres (SRS). The α-(hydroxymethyl)-(S)-prolinato complex, (+)578-p-[Co(tren){(RC,SN)-Pro(CH2OH)O}]Cl2·2H2O (23) resulted from borohydride reduction of 22. The molecular structures of (+)578-p-[Co(tren){(RC,SN)-Pro[CH(OH)2]O}]Cl2·2H...

  13. Microwave combustion and sintering without isostatic pressure

    International Nuclear Information System (INIS)

    Ebadian, M.A.

    1998-01-01

    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

  14. Ex Situ Formation of Metal Selenide Quantum Dots Using Bacterially Derived Selenide Precursors

    Energy Technology Data Exchange (ETDEWEB)

    Fellowes, Jonathan W.; Pattrick, Richard; Lloyd, Jon; Charnock, John M.; Coker, Victoria S.; Mosselmans, JFW; Weng, Tsu-Chien; Pearce, Carolyn I.

    2013-04-12

    Luminescent quantum dots were synthesized using bacterially derived selenide (SeII-) as the precursor. Biogenic SeII- was produced by the reduction of Se-IV by Veillonella atypica and compared directly against borohydride-reduced Se-IV for the production of glutathione-stabilized CdSe and beta-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.

  15. Substrate-Independent Ag-Nanoparticle-Loaded Hydrogel Coating with Regenerable Bactericidal and Thermoresponsive Antibacterial Properties.

    Science.gov (United States)

    He, Min; Wang, Qian; Zhang, Jue; Zhao, Weifeng; Zhao, Changsheng

    2017-12-27

    We report a Ag-nanoparticle (AgNP)-based substrate-independent bactericidal hydrogel coating with thermoresponsive antibacterial property. To attach the hydrogel coating onto model substrate, we first coated ene-functionalized dopamine on the substrate, and then the hydrogel thin layer was formed on the surface via the UV light initiated surface cross-linking copolymerization of N-isopropylacrylamide (NIPAAm) and sodium acrylate (AANa). Then, Ag ions were adsorbed into the hydrogel layers and reduced to AgNPs by sodium borohydride. The coating showed robust bactericidal ability against Escherichia coli and Staphylococcus aureus toward both contacted bacteria and the bacteria in the surrounding. Upon a reduction of the temperature below the LCST of PNIPAAm, the improved surface hydrophilicity and swollen PNIPAAm could detach the attached dead bacteria. Meanwhile, the long-lasting and regenerable antibacterial properties could be achieved by repeatedly loading AgNPs. By precisely controlling the AgNP loading amounts, the coating showed excellent hemocompatibility and no cytotoxity. Additionally, the coating could be applied to modify cell culture plate, since it could support cell adhesion and proliferation at 37 °C, while detach the cell by changing the temperature below lower critical solution temperature without the treatment of proteases. The study thus presents a promising way to fabricate thermoresponsive and regenerable antibacterial surfaces on diverse materials and devices for biomedical applications.

  16. Dendrimer-encapsulated silver nanoparticles and antibacterial activity on cotton fabric.

    Science.gov (United States)

    Tang, Jianxin; Chen, Wenjing; Su, Wei; Li, Wen; Deng, Jing

    2013-03-01

    Silver-dendrimer nanocomposites are synthesized in the presence low generation poly(amido amine) dendrimers with terminal amine groups employing silver nitrate as the precursor and sodium borohydride as the reduction agent. The parameters including the addition of oxalic acid and the generation of the dendrimer that influence the particle size of the synthesized silver nanoparticles are discussed. Under the optimized conditions, a series of silver-dendrimer nanocomposites with the average diameter of silver nanoparticles ranging from 7.6 nm to 16.2 nm are synthesized by varying the molar ratio of dendrimer to silver nitrate. The synthesized silver-dendrimer nanocomposites are utilized as the antibacterial agents in fabrication of antibacterial cotton fabrics. The antimicrobial properties of the prepared antibacterial cotton fabrics against E. coli and S. aureus are evaluated by the inhibition zone method. The results demonstrate that the antimicrobial activity of the silver-dendrimer composites treated cotton fabric enhances with the decrease of the silver nanoparticle size.

  17. Starch-supported gold nanoparticles and their use in 4-nitrophenol reduction

    Directory of Open Access Journals (Sweden)

    Sanoe Chairam

    2017-09-01

    Full Text Available Gold nanoparticles (AuNPs have been synthesized through a green synthesis method using mung bean starch (MBS as both reducing and stabilizing agents. The chemical state was analyzed by X-ray photoelectron spectroscopy (XPS. The crystalline structures were characterized by X-ray diffraction (XRD. The thermal properties were measured by thermogravimetric analysis and differential thermal analysis (TGA/DTA. The surface morphology was investigated by scanning electron microscopy (SEM. In order to investigate the catalytic activity, the mung bean starch-supported AuNPs (MBS-AuNPs was utilized as a heterogeneous catalyst in the reduction of 4-nitrophenol (4-NP in the presence of sodium borohydride (NaBH4. The kinetic studies under the different experimental conditions were performed in order to determine the activation parameters from the Arrhenius and Eyring equations. It was found that the activation energy (Ea, activation enthalpy (ΔH# and activation entropy (ΔS# were calculated to be 47.42 kJ mol−1, 44.78 kJ mol−1 and −261.49 kJ mol−1, respectively. In addition, the catalytic activity was 73% reduction after recycling at the end of the fifth use. This work offers a non-toxic procedure for the synthesis of nanoparticles using starch-rich polymers with a great promise toward other potential applications.

  18. Catalytic Reductive Degradation of Methyl Orange Using Air Resilient Copper Nanostructures

    Directory of Open Access Journals (Sweden)

    Razium Ali Soomro

    2015-01-01

    Full Text Available The study describes the application of oxidation resistant copper nanostructures as an efficient heterogeneous catalyst for the treatment of organic dye containing waste waters. Copper nanostructures were synthesized in an aqueous environment using modified surfactant assisted chemical reduction route. The synthesized nanostructures have been characterized by UV-Vis, Fourier transform infrared spectroscopy FTIR spectroscopy, Atomic force microscopy (AFM, Scanning Electron Microscopy (SEM, and X-ray diffractometry (XRD. These surfactant capped Cu nanostructures have been used as a heterogeneous catalyst for the comparative reductive degradation of methyl orange (MO in the presence of sodium borohydride (NaBH4 used as a potential reductant. Copper nanoparticles (Cu NPs were found to be more efficient compared to copper nanorods (Cu NRds with the degradation reaction obeying pseudofirst order reaction kinetics. Shape dependent catalytic efficiency was further evaluated from activation energy (EA of reductive degradation reaction. The more efficient Cu NPs were further employed for reductive degradation of real waste water samples containing dyes collected from the drain of different local textile industries situated in Hyderabad region, Pakistan.

  19. Catalytic and recyclability properties of phytogenic copper oxide nanoparticles derived from Aglaia elaeagnoidea flower extract

    Directory of Open Access Journals (Sweden)

    G. Manjari

    2017-07-01

    Full Text Available The phytogenic synthesis method to highly active, recoverable and recyclable heterogeneous copper oxide nanocatalyst and encapsulated within biomaterial that acts as a nontoxic and renewable source of reducing and stabilizing agent. The biosynthesized CuO NPs were characterized using UV–Vis absorption spectroscopy, X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, energy dispersive X-ray spectroscopy (EDX, transmission electron microscopy (TEM and thermo gravimetric analysis-differential scanning calorimetry (TGA–DSC, techniques. The formation of CuO NPs with the size 20–45 nm range is shown in TEM image. Significantly, in aqueous phase CuO NPs have high catalytic activity for the reduction of Congo red (CR, methylene blue (MB and 4-nitrophenol (4-NP in the presence of the sodium borohydride (NaBH4 at room temperature. In addition, CuO NPs catalyst can be easily recovered by centrifugation and reused for 6 cycles with more than 90% conversion efficiency. CuO nanocatalyst, leaching after catalytic application was investigated by ICPAES (Inductively coupled plasma atomic emission spectroscopy. CuO NPs possess great prospects in reduction of pernicious dyes and nitro organic pollutants in water.

  20. 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.)

  1. Promotion effect of manganese oxide on the electrocatalytic activity of Pt/C for methanol oxidation in acid medium

    Science.gov (United States)

    Abdel Hameed, R. M.; Fetohi, Amani E.; Amin, R. S.; El-Khatib, K. M.

    2015-12-01

    The modification of Pt/C by incorporating metal oxides for electrocatalytic oxidation of methanol has gained major attention because of the efficiency loss during the course of long-time operation. This work describes the preparation of Pt-MnO2/C electrocatalysts through a chemical route using ethylene glycol or a mixture of ethylene glycol and sodium borohydride as a reducing agent. The crystallite structure and particle size of synthesized electrocatalysts are determined using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The addition of MnO2 improves the dispersion of Pt nanoparticles. The electrocatalytic activity of Pt-MnO2/C towards methanol oxidation in H2SO4 solution is investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The onset potential value of methanol oxidation peak is negatively shifted by 169 mV when MnO2 is introduced to Pt/C. Moreover, the charge transfer resistance value at Pt-MnO2/C is about 10 times as low as that at Pt/C. Chronoamperometry and chronopotentiometry show that CO tolerance is greatly improved at Pt-MnO2/C. The increased electrocatalytic activity and enhanced ability to clean platinum surface elect manganese oxide as a suitable promoter for the anode performance in direct methanol fuel cells (DMFCs).

  2. Laser Ablated Silver Nanoparticles with Nearly the Same Size in Different Carrier Media

    Directory of Open Access Journals (Sweden)

    Antonio M. Brito-Silva

    2010-01-01

    Full Text Available Poly(vinyl-pyrrolidone (PVP stabilized silver nanoparticles with an average particle size ranging from 4.3 to 4.9 nm were synthesized by laser ablation in preformed colloids in methanol, acetone, ethylene glycol, and glycerin. Aqueous colloids obtained using PVP, poly(vinyl-alcohol (PVA, and sodium citrate as stabilizing agents also lead to a good control over particle size distribution. Silver ions were reduced with sodium borohydride. The smaller average particle size and narrower dispersivity in comparison to previously reported data were ascribed to the relatively small size of the particles formed in the chemical reduction step, laser fluence, and the use of PVP, which was not previously used as the stabilizing agent in “top-down” routes. The surface plasmon resonance band maximum wavelength shifted from 398 nm in methanol to 425 nm in glycerin. This shift must be due to solvent effects since all other variables were the same.

  3. So you've got your sample in solution. What next? (W7)

    International Nuclear Information System (INIS)

    Brindle, I.P.

    2002-01-01

    Full text: Several factors must be considered after the sample is prepared for analysis. These factors include memory, oxidation state of analyte, presence of interfering elements, etc. Some elements are 'sticky' and exhibit prodigious memory effects. For elements like mercury, gold and boron, memory effects make it difficult to determine elemental concentrations in samples that vary widely in concentration. When selenium is determined by hydride generation, the selenium cannot be in the VI oxidation state, since borohydride will not reduce this oxidation state. Different treatments must be used. The treatment of organometallics may require, in addition, the presence of reagents to improve the yield of derivitized species that are to be determined. Interfering elements must sometimes be masked or removed before determination of the analyte can proceed. In this presentation, these various issues will be discussed. Solutions to some of the problems, from the analytical chemistry laboratories at Brock University, will be presented. In addition, options for the simultaneous determination of elements by vapor generation and nebulization will be discussed, based on recent work in the Brock laboratories. (author)

  4. 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.

  5. Electrocatalysts Prepared by Galvanic Replacement

    Directory of Open Access Journals (Sweden)

    Athanasios Papaderakis

    2017-03-01

    Full Text Available Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, Mnoble, when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mMnoblen+ → nMm+ + mMnoble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases hydrogen evolution too, both oxygen levels and the pH must be optimized. The resulting bimetallic material can in principle have a Mnoble-rich shell and M-rich core (denoted as Mnoble(M leading to a possible decrease in noble metal loading and the modification of its properties by the underlying metal M. This paper reviews a number of bimetallic or ternary electrocatalytic materials prepared by galvanic replacement for fuel cell, electrolysis and electrosynthesis reactions. These include oxygen reduction, methanol, formic acid and ethanol oxidation, hydrogen evolution and oxidation, oxygen evolution, borohydride oxidation, and halide reduction. Methods for depositing the precursor metal M on the support material (electrodeposition, electroless deposition, photodeposition as well as the various options for the support are also reviewed.

  6. Inhibition of glycation of albumin and hemoglobin by acetylation in vitro and in vivo.

    Science.gov (United States)

    Rendell, M; Nierenberg, J; Brannan, C; Valentine, J L; Stephen, P M; Dodds, S; Mercer, P; Smith, P K; Walder, J

    1986-10-01

    Aspirin (acetylsalicylic acid or ASA) is known to inhibit glycosylation (glycation) of albumin in vitro. The mechanism has been presumed to be acetylation, but this has never been validated. The new affinity aminophenylboronic acid procedure for determination of glycosylated albumin was used to demonstrate inhibition of glycosylation by aspirin. ASA, but not salicylic acid, inhibited glycation. The inhibition of glycation by equimolar acetic anhydride was greater than that by ASA. Pretreatment of albumin with ASA in the absence of glucose demonstrated that inhibition was extremely rapid, occurring in a matter of minutes. However, the inhibition by ASA could not be prevented by massive acceleration of glycation induced by borohydride reduction. Glycation of hemoglobin was also inhibited by ASA, but the dose requirement was considerably higher. Various analogues of ASA were evaluated for inhibition of glycation. Only acetyl-5-ethylsalicylic acid was more effective than ASA in inhibiting albumin glycation. None of these agents was more potent than ASA in inhibiting glycation of hemoglobin. ASA was fed to diabetic rats in a long-term experiment. Glycohemoglobin and glycoalbumin levels were decreased by ASA administration. We conclude that ASA inhibits glycation by a very rapid acetylation process. This process is apparently quite selective in terms of the protein involved, presumably because of the local environment of affected lysine groups. The phenomenon can be produced in vivo by administration of ASA.

  7. Reviewing the Tannic Acid Mediated Synthesis of Metal Nanoparticles

    International Nuclear Information System (INIS)

    Ahmad, T.

    2014-01-01

    Metal nanoparticles harbour numerous exceptional physiochemical properties absolutely different from those of bulk metal as a function of their extremely small size and large superficial area to volume. Naked metal nanoparticles are synthesized by various physical and chemical methods. Chemical methods involving metal salt reduction in solution enjoy an extra edge over other protocols owing to their relative facileness and capability of controlling particle size along with the attribute of surface tailoring. Although chemical methods are the easiest, they are marred by the use of hazardous chemicals such as borohydrides. This has led to inclination of scientific community towards eco-friendly agents for the reduction of metal salts to form nanoparticles. Tannic acid, a plant derived polyphenolic compound, is one such agent which embodies characteristics of being harmless and environmentally friendly combined with being a good reducing and stabilizing agent. In this review, first various methods used to prepare metal nanoparticles are highlighted and further tannic acid mediated synthesis of metal nanoparticles is emphasized. This review brings forth the most recent findings on this issue.

  8. 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

    2014-07-15

    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 (111), (200), (222) and (311) 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. A microwave assisted one-pot route synthesis of bimetallic PtPd alloy cubic nanocomposites and their catalytic reduction for 4-nitrophenol

    Science.gov (United States)

    Zhang, Jian; Gan, Wei; Fu, Xucheng; Hao, Hequn

    2017-10-01

    We herein report a simple, rapid, and eco-friendly chemical route to the one-pot synthesis of bimetallic PtPd alloy cubic nanocomposites under microwave irradiation. During this process, water was employed as an environmentally benign solvent, while dimethylformamide served as a mild reducing agent, and polyvinylpyrrolidone was used as both a dispersant and a stabilizer. The structure, morphology, and composition of the resulting alloy nanocomposites were examined by x-ray diffraction, transmission electron microscopy, and energy dispersive x-ray spectroscopy. A detailed study was then carried out into the catalytic activity of the PtPd nanocomposites with a Pt:Pd molar ratio of 50:50 in the reduction of 4-nitrophenol (4-NP) by sodium borohydride as a model reaction. Compared with pristine Pt and Pd monometallic nanoparticles (PtNPs and PdNPs), the bimetallic PtPd alloy nanocomposites exhibited enhanced catalytic activities and were readily recyclable in the reduction of 4-NP due to synergistic effects.

  10. Reviewing the Tannic Acid Mediated Synthesis of Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Tufail Ahmad

    2014-01-01

    Full Text Available Metal nanoparticles harbour numerous exceptional physiochemical properties absolutely different from those of bulk metal as a function of their extremely small size and large superficial area to volume. Naked metal nanoparticles are synthesized by various physical and chemical methods. Chemical methods involving metal salt reduction in solution enjoy an extra edge over other protocols owing to their relative facileness and capability of controlling particle size along with the attribute of surface tailoring. Although chemical methods are the easiest, they are marred by the use of hazardous chemicals such as borohydrides. This has led to inclination of scientific community towards eco-friendly agents for the reduction of metal salts to form nanoparticles. Tannic acid, a plant derived polyphenolic compound, is one such agent which embodies characteristics of being harmless and environmentally friendly combined with being a good reducing and stabilizing agent. In this review, first various methods used to prepare metal nanoparticles are highlighted and further tannic acid mediated synthesis of metal nanoparticles is emphasized. This review brings forth the most recent findings on this issue.

  11. Green synthesis of palladium nanoparticles with carboxymethyl cellulose for degradation of azo-dyes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang; Li, Yun; Wang, Zhengdong; Liu, Huihong, E-mail: huihongliu@126.com

    2017-02-01

    Palladium nanoparticles (PdNPs) were synthesized through friendly environmental method using PdCl{sub 2} and carboxymethyl cellulose (CMC) in an aqueous solution (pH 6) at controlled water bath (80 °C) for 30 min. CMC functioned as both reducing and stabilizing agent. The characterization through high resolution-transmission electron microscopic (HRTEM) and X-ray Fluorescence Spectrometry (XRF) inferred that the as-synthesized PdNPs were spherical in shape with a face cubic crystal (FCC) structure. The results from dynamic light scattering (DLS) suggested the PdNPs had the narrow size distribution with an average size of 2.5 nm. The negative zeta potential (−52.6 mV) kept the as-synthesized PdNPs stable more than one year. The PdNPs showed the excellent catalytic activity by reducing degradation of azo-dyes, such as p-Aminoazobenzene, acid red 66, acid orange 7, scarlet 3G and reactive yellow 179, in the present of sodium borohydride. - Highlights: • Green synthesis of palladium nanoparticles using carboxymethyl cellulose. • The synthesis of palladium nanoparticles were performed easily. • Carboxymethyl cellulose acts as both reducing and stabilization agents. • The as-synthesized palladium nanoparticles show excellent catalytic activity.

  12. Hydrophilic silver nanoparticles with tunable optical properties: application for the detection of heavy metals in water

    Directory of Open Access Journals (Sweden)

    Paolo Prosposito

    2016-11-01

    Full Text Available Due their excellent chemo-physical properties and ability to exhibit surface plasmon resonance, silver nanoparticles (AgNPs have become a material of choice in various applications, such as nanosensors, electronic devices, nanobiotechnology and nanomedicine. In particular, from the environmental monitoring perspective, sensors based on silver nanoparticles are in great demand because of their antibacterial and inexpensive synthetic method. In the present study, we synthesized AgNPs in water phase using silver nitrate as precursor molecules, hydrophilic thiol (3-mercapto-1-propanesulfonic acid sodium salt, 3MPS and sodium borohydride as capping and reducing agents, respectively. The AgNPs were characterized using techniques such as surface plasmon resonance (SPR spectroscopy, dynamic light scattering (DLS, zeta potential (ζ-potential measurements and scanning tunneling microscopy (STM. Further, to demonstrate the environmental application of our AgNPs, we also applied them for heavy metal sensing by detecting visible color modification due to SPR spectral changes. We found that these negatively charged AgNPs show good response to nickel (II and presented good sensibility properties for the detection of low amount of ions in water in the working range of 1.0–0.1 ppm.

  13. Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors

    International Nuclear Information System (INIS)

    Fellowes, J W; Pattrick, R A D; Lloyd, J R; Charnock, J M; Coker, V S; Mosselmans, J F W; Weng, T-C; Pearce, C I

    2013-01-01

    Luminescent quantum dots were synthesized using bacterially derived selenide (Se II− ) as the precursor. Biogenic Se II− was produced by the reduction of Se IV by Veillonella atypica and compared directly against borohydride-reduced Se IV for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological Se II− 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 Se II− 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 Se II− 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)

  14. 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.

  15. Leucoanthocyanidins as intermediates in anthocyanidin biosynthesis in flowers of Matthiola incana R. Br.

    Science.gov (United States)

    Heller, W; Britsch, L; Forkmann, G; Grisebach, H

    1985-02-01

    (+)Leucopelargonidin [(2R,3S,4R)-3,4,5,7,4'-pentahydroxyflavan] and (+)leucocyanidin [(2R,3S,4R)-3,4,5,7,3',4'-hexahydroxyflavan] were synthesized from (+)dihydrokaempferol and (+)dihydroquercetin, respectively, by sodium-borohydride reduction. The chemical and optical purity of these compounds was established by ultraviolet, proton-nuclear-magnetic-resonance, and optical-rotatory-dispersion spectroscopy. Supplementation experiments with these leucoanthocyanidins were carried out with genetically defined acyanic flowers of Matthiola incana. Feeding of leucopelargonidin and leucocyanidin to line 17 (blocked between dihydroflavonols and anthocyanins) and line 18 (blocked in the chalcone-synthase gene) led to formation of the corresponding anthocyanidin 3-O-glucosides, whereas supplementation of line 19 (blocked in a locus other than line 17 between dihydroflavonols and anthocyanins) did not result in anthocyanin synthesis. The conversion of leucopelargonidin into pelargonidin 3-O-glucoside was further confirmed by incorporation of [4-(3)H]leucopelargonidin into pelargonidin derivatives. The results are strong indications for the role of leucoanthocyanidins (flavan-3,4-diols) as intermediates in anthocyanin biosynthesis.

  16. Dynamic nuclear polarization of irradiated target materials

    International Nuclear Information System (INIS)

    Seely, M.L.

    1982-01-01

    Polarized nucleon targets used in high energy physics experiments usually employ the method of dynamic nuclear polarization (DNP) to polarize the protons or deuterons in an alcohol. DNP requires the presence of paramagnetic centers, which are customarily provided by a chemical dopant. These chemically doped targets have a relatively low polarizable nucleon content and suffer from loss of polarization when subjected to high doses of ionizing radiation. If the paramagnetic centers formed when the target is irradiated can be used in the DNP process, it becomes possible to produce targets using materials which have a relatively high polarizable nucleon content, but which are not easily doped by chemical means. Furthermore, the polarization of such targets may be much more radiation resistant. Dynamic nuclear polarization in ammonia, deuterated ammonia, ammonium hydroxide, methylamine, borane ammonia, butonal, ethane and lithium borohydride has been studied. These studies were conducted at the Stanford Linear Accelerator Center using the Yale-SLAC polarized target system. Results indicate that the use of ammonia and deuterated ammonia as polarized target materials would make significant increases in polarized target performance possible

  17. 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.

  18. 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.

  19. Synthesis, Characterization and Gas Sensing Properties of Ag@α-Fe2O3 Core–Shell Nanocomposites

    Directory of Open Access Journals (Sweden)

    Ali Mirzaei

    2015-05-01

    Full Text Available Ag@α-Fe2O3 nanocomposite having a core–shell structure was synthesized by a two-step reduction-sol gel approach, including Ag nanoparticles synthesis by sodium borohydride as the reducing agent in a first step and the subsequent mixing with a Fe+3 sol for α-Fe2O3 coating. The synthesized Ag@α-Fe2O3 nanocomposite has been characterized by various techniques, such as SEM, TEM and UV-Vis spectroscopy. The electrical and gas sensing properties of the synthesized composite towards low concentrations of ethanol have been evaluated. The Ag@α-Fe2O3 nanocomposite showed better sensing characteristics than the pure α-Fe2O3. The peculiar hierarchical nano-architecture and the chemical and electronic sensitization effect of Ag nanoparticles in Ag@α-Fe2O3 sensors were postulated to play a key role in modulating gas-sensing properties in comparison to pristine α-Fe2O3 sensors.

  20. Tailoring Cu Nanoparticle Catalyst for Methanol Synthesis Using the Spinning Disk Reactor.

    Science.gov (United States)

    Ahoba-Sam, Christian; Boodhoo, Kamelia V K; Olsbye, Unni; Jens, Klaus-Joachim

    2018-01-17

    Cu nanoparticles are known to be very active for methanol (MeOH) synthesis at relatively low temperatures, such that smaller particle sizes yield better MeOH productivity. We aimed to control Cu nanoparticle (NP) size and size distribution for catalysing MeOH synthesis, by using the spinning disk reactor. The spinning disk reactor (SDR), which operates based on shear effect and plug flow in thin films, can be used to rapidly micro-mix reactants in order to control nucleation and particle growth for uniform particle size distribution. This could be achieved by varying both physical and chemical operation conditions in a precipitation reaction on the SDR. We have used the SDR for a Cu borohydride reduction to vary Cu NP size from 3 nm to about 55 nm. XRD and TEM characterization confirmed the presence of Cu₂O and Cu crystallites when the samples were dried. This technique is readily scalable for Cu NP production by processing continuously over a longer duration than the small-scale tests. However, separation of the nanoparticles from solution posed a challenge as the suspension hardly settled. The Cu NPs produced were tested to be active catalyst for MeOH synthesis at low temperature and MeOH productivity increased with decreasing particle size.