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Search Results: 1 - 10 of 559 matches for " Cobalt Porphyrine "
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AZA NITROGENS EFFECT ON THE ELECTRONIC PROPERTIES OF COBALT PORPHYRINE AND DERIVATIVES
Cárdenas-Jirón,Gloria I.;
Journal of the Chilean Chemical Society , 2004, DOI: 10.4067/S0717-97072004000100017
Abstract: a set of electronic properties calculated at the b3lyp/lacvp(d) level of theory for four cobalt macrocycles containing a ligand like porphyrin (cop) and a benzoporphyrin (cotbp) has been analyzed. the effect of aza nitrogen atoms (aza-n) present in the ligand (cotap, copc) on the electronic properties chosen has been studied. for the pair cop/cotap we found a notorious effect of the presence of aza-n atoms in each electronic property studied. however, for the pair cotbp/copc a different result was obtained. the dipole moment and the atomic charges, the latter evaluated on the cobalt atom and on the aza-n atoms, do not show the isolated effect of the aza nitrogen atoms and rather it appears to be mixed with the effect produced by the ligand size. on the contrary, electronic properties such as spin density and electrostatic potential evaluated on the cobalt atom clearly show the effect of the aza nitrogen atoms predicting that the latter present an electron withdrawing behavior in this kind of molecules
AZA NITROGENS EFFECT ON THE ELECTRONIC PROPERTIES OF COBALT PORPHYRINE AND DERIVATIVES
Gloria I. Cárdenas-Jirón
Journal of the Chilean Chemical Society , 2004,
Abstract: A set of electronic properties calculated at the B3LYP/LACVP(d) level of theory for four cobalt macrocycles containing a ligand like porphyrin (CoP) and a benzoporphyrin (CoTBP) has been analyzed. The effect of aza nitrogen atoms (aza-N) present in the ligand (CoTAP, CoPc) on the electronic properties chosen has been studied. For the pair CoP/CoTAP we found a notorious effect of the presence of aza-N atoms in each electronic property studied. However, for the pair CoTBP/CoPc a different result was obtained. The dipole moment and the atomic charges, the latter evaluated on the cobalt atom and on the aza-N atoms, do not show the isolated effect of the aza nitrogen atoms and rather it appears to be mixed with the effect produced by the ligand size. On the contrary, electronic properties such as spin density and electrostatic potential evaluated on the cobalt atom clearly show the effect of the aza nitrogen atoms predicting that the latter present an electron withdrawing behavior in this kind of molecules
Odor sensor based on the information of colour
Fang Han,Takanori Inoue,Teppei Wasai,Yoshiaki Kurauchi
Journal of Engineering and Applied Sciences , 2006,
Abstract: An odor sensor was developed for the detection of volatile organic compounds (VOCs). The responsive elements of the odor sensor used in the study were: seven types of metal-porphyrine; Reichardt’s Dye (R-Dye) and six pH indicators. The characteristics of responsive elements of the odor sensor have been described. Under the conditions of hydrophobic polymers, there were various responses for low hydrophobic gases and under the conditions of hydrophilic polymers, there were multi-responses for the gases of high hydrophobe. The present study of the odor sense system with basic function of odor sense confirmed the above description.
Effect of the Preparation Method on Co/Al2O3 Catalyst Applied to Ethanol Steam Reforming Reaction Production of Hydrogen  [PDF]
Silmara Rodrigues Garcia, José Mansur Assaf
Modern Research in Catalysis (MRC) , 2012, DOI: 10.4236/mrc.2012.13007
Abstract: Alumina supported cobalt catalysts were prepared, characterized and applied in ethanol steam reforming for hydrogen production. The support and the supported catalysts were prepared, respectively, by the solvothermal and precipitation, impregnation and deposition-precipitation methods. The cobalt was added by impregnation and deposition-precipitation in the Al2O3 supports using a Co(NO3)2·6H2O solution. The solids were characterized, Temperature-Programmed Re-duction with H2 (RTP-H2), X-Ray Diffraction (DRX), BET Nitrogen Adsorption and Temperature Programmed Oxida-tion (TPO). The results indicated that the preparation method and the treatment conditions of samples were appropriate for obtaining the wanted compounds. Co3O4 phase was verified for all catalysts through analyses of DRX and RTP-H2 results. Catalytic tests were performed by varying the temperature from 450?C to 600?C, with water: ethanol molar ratio of 3:1. The ethanol conversion was superior of 99%, with greater hydrogen yield at 600℃. The lower carbon deposition was observed in catalysts prepared with solvothermal/deposition-precipitation methods at 450℃.
Enhanced Electrocatalytic Reduction of Oxygen at Electrodes Coated with a Multi-Metallic Co(II)/Pt(II) Porphyrin  [PDF]
Shawn Swavey, David Fresh
American Journal of Analytical Chemistry (AJAC) , 2013, DOI: 10.4236/ajac.2013.410A1007
Abstract: Edge plane pyrolytic graphite (EPG) electrodes coated with the Co(II)/Pt(II)2 analog of 5,15-bis-(4-pyridyl)-10,20-bis-(3-methoxy-4-hydroxyphenyl)porphyrin undergo an electrochemical-chemical-electrochemical (ECE) reaction when anodically scanned in 1.0 M sulfuric acid. The new redox couple formed from this anodic conditioning of the coated electrode is dependent on the pH of the solution. Roughened EPG electrodes coated with the Co(II)/Pt(II)2 trimetallic porphyrin show a catalytic shift of 400 mV for the reduction of O2 when compared to the reduction of O2 at a bare EPG electrode. An additional catalytic shift of ca. 150 mV is observed for O2 reduction at an EPG electrode coated with the Co(II)/Pt(II)2 porphyrin which has been oxidized in 1.0 M sulfuric acid. In addition to the added electrocatalysis, a significant percentage of O2 reduced at the oxidized Co(II)/Pt(II)2 EPG electrode is converted to H2O as determined by rotating disk electrode measurements.

Electrolytic Cobalt Removal in Wastewater  [PDF]
Isabela O. Santos, Isaque C. A. Santos, Leandro V. Pontual, Luciane P. C. Monteiro, Fernando B. Mainier
Journal of Environmental Protection (JEP) , 2016, DOI: 10.4236/jep.2016.75065
Abstract:

Industrial effluents containing cobalt ions have become a serious problem for the environment, unless properly treated, due to their toxic potential. Currently there has been an intensification of the use of cobalt in several industrial sectors as super alloys, catalysts, batteries and pigments in ceramic materials, and a consequent intensification also of environmental contamination. This paper aims to show a simple and effective treatment for the removal of cobalt ions from simulated industrial wastewater, based on cathodic eletrolytic removal using a carbon steel screen. As a result, a 73% removal of cobalt ions from solutions was achieved with a concentration of 400 mg Co2+/L, a current of 0.30 A and a voltage of 30 V. In the same conditions, 84% and 88% was removed from 200 mg Co2+/L and 100 mg Co2+/L, respectively. Thus, this method presents itself as a cheap and efficient alternative for the treatment of industrial effluents containing cobalt ions.

Hydrothermally Synthesized NanobioMOFs, Evaluated by Photocatalytic Hydrogen Generation  [PDF]
Tabinda Sattar, Muhammad Athar
Modern Research in Catalysis (MRC) , 2017, DOI: 10.4236/mrc.2017.62007
Abstract: Three new materials, nanobioMOFs (cobalt argeninate, cobalt asparaginate and cobalt glutaminate) have been hydrothermally synthesized. Nano sized morphology of all these materials have been obtained by scanning electron microscopic technique. Mass spectrometric studies of all these materials have been conducted for determination of their molar masses. All these nanobioMOFs have been found to exhibit photocatalytic hydrogen generation in pure water upon irradiation at wavelengths longer than 650 nm. The amounts of quantum yield of hydrogen generation at 650 nm in water was 4.5%, 4.0% and 3.5% for cobalt argeninate, cobalt asparaginate and cobalt glutaminate respectively. The apparently higher yield of hydrogen generation from these amine functionalized nanobioMOFs can direct to the development of more nano sized functionalized MOFs for water splitting.
Nanopartículas magnéticas: o cobalto
Sargentelli, Vagner;Ferreira, Antonio P.;
Eclética Química , 2010, DOI: 10.1590/S0100-46702010000400020
Abstract: the development of nanoparticles has been intensively pursued because of their technological importance. the magnetic nanoparticulate materials exhibit a series of interesting properties between which are mentioned the electrical, optical, magnetic and chemical properties. magnetic nanostructures can be used in microelectronic and in medicine as in: magnetic memory storage, magnetic transport of biochemical complexes, magnetic resonance imaging, among others. the magnetic properties of nanoparticles there are very sensitive to its size and form. in this direction, many efforts they have been carried through with the intention of to control the form and distribution of the size of the nanoparticles. in the last few decades nanoparticles constituted by iron oxides had been studied. however, more recently, the focus of the researches has come back to others transitions metals. amongst these, the cobalt comes being investigated due to its high magnetic susceptibility. in this context, the present article has the aim of to presents and to effect a comparative analysis of the more significant synthetic ways utilized in the present moment to obtain cobalt nanoparticles.
Preparation of Ni-Co Alloy Foils by Electrodeposition  [PDF]
Yu-Yang Yang, Bin Deng
Advances in Chemical Engineering and Science (ACES) , 2011, DOI: 10.4236/aces.2011.12005
Abstract: Electrodeposition of Ni-Co alloy foils on titanium substrate was performed in an acid chloride- sulphate bath. The influences of electrodeposition parameters such as current density, temperature, pH value, cobalt sulphate and saccharin concentration on composition and current efficiency were investigated in detail. The morphology and the microstructure of deposits were analyzed by SEM and XRD, respectively. The results indicated that the optimum parameters were current density 3-4 A/dm2, pH 2-3, temperature 40-50?C, cobalt sulphate 20 g/l and saccharin 2-3 g/l. Chemical analysis of the deposits by EDS revealed anomalous Ni-Co codeposition occured in this system. The SEM showed that hydroxide particles were not present on the surface and that fine-grain, smooth and compact Ni-Co alloy deposits were obtained. The crystallographic structures of Ni-Co alloy foils were the fcc Ni solid solution. The Ni-Co alloy foils with Co content 17.3-37.2 wt% and thickness of 20-45 μm were bright with low residual stress and super toughness.
Sustainable Land Management: Growing Miscanthus in Soils Contaminated with Heavy Metals  [PDF]
Valentina Pidlisnyuk, Larry Erickson, Sergiy Kharchenko, Tetyana Stefanovska
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.58073
Abstract:

Miscanthus grows well in some marginal and contaminated soils, and it has the potential to be used as a biofuel. Copper and cobalt are heavy metals that sometimes are present as contaminants in soils at concentrations that may impact the safety of products that are harvested. Laboratory research has been conducted with Miscanthus sacchariflorus M. to investigate metal uptake of copper and cobalt because metal concentrations in the harvested parts of miscanthus are important for biofuel applications. The results show that the use of miscanthus for biofuel from soil contaminated by heavy metals depends mainly on the nature of contaminated metals: cobalt was detected only for highest treated concentration of metal and mainly in the roots. The highest concentration of copper was detected in the roots however this metal was detected in stems and leaves of miscanthus as well. Miscanthus biomass harvested from cobalt contaminated soil may be used for energy production because the harvested part accumulated only limited traces of the metal. The experimental results are in reasonable agreement with other results from the literature.

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