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Copper Oxide (copper + oxide)

Distribution by Scientific Domains

Chemistry	68%
Polymers and Materials Science	25%

Selected Abstracts

Copper Oxide , Graphite Composite Electrodes: Application to Nitrite Sensing

ELECTROANALYSIS, Issue 1 2007
Biljana, ljuki
Abstract A simple method for the modification of carbon powder with copper oxides is presented. Carbon powder is impregnated with copper(II) nitrate by stirring carbon powder in copper(II) nitrate solution for 1 hour and subsequently thermally treated at 823,K. The modified carbon powder was characterized using electrochemical and spectroscopic techniques. The existence of both copper(I) and copper(II) oxides have been established. The copper oxide modified carbon powder was used for preparation of composite electrodes, and the electrochemical and electrocatalytic behavior of the resulting composite electrodes was studied. The copper oxide modified carbon powder , epoxy composite electrodes showed a high electrocatalytic activity for the nitrite detection in aqueous media, with the detection limit comparable or lower than detection limits obtained with other electrochemical sensors. [source]

ChemInform Abstract: Nanocrystalline Copper Oxide(II)-Catalyzed Alkyne-Azide Cycloadditions.

CHEMINFORM, Issue 1 2009
Young-Jin Song
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Ag2CuMnO4: A New Silver Copper Oxide with Delafossite Structure.

CHEMINFORM, Issue 11 2007
Nieves Casan-Pastor
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Microstructural Morphology and Electrical Properties of Copper- and Niobium-Doped Tin Dioxide Polycrystalline Varistors

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2006
Chun-Ming Wang
The influence of a Nb2O5 additive on the densification, microstructural morphology, and nonlinear electrical properties of the CuO-doped SnO2 -based varistors was investigated. It was found that copper oxide significantly improves the densification of the SnO2 ceramics. The effects of Nb2O5 on tin dioxide varistors were analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and capacitance,voltage measurements, as well as impedance spectroscopy. Copper oxide segregates at the grain boundaries and precipitates at triple points, and niobium makes the tin dioxide grain semi-conductive. The copper oxide intergranular insulating layer separates two semi-conductive tin dioxide grains and forms the barriers. The reason for the nonlinearity of SnO2 -based ceramics was explained. [source]

Improving MCM-41 as a Nitrosamines Trap through a One-Pot Synthesis

CHEMISTRY - AN ASIAN JOURNAL, Issue 8 2007
Jia Hui Xu
Abstract Copper oxide was incorporated into MCM-41 by a one-pot synthesis under acidic conditions to prepare a new mesoporous nitrosamines trap for protection of the environment. The resulting composites were characterized by XRD, N2 adsorption,desorption, and H2 temperature-programmed reduction techniques, and their adsorption capabilities were assessed in the gaseous adsorption of N -nitrosopyrrolidine (NPYR). The adsorption isotherms were consistent with the Freundlich equation. The copper salt was deposited onto MCM-41 during the evaporation stage and was fixed on the host in the calcination process that followed. MCM-41 was able to capture NPYR in air below 373,K but not at 453,K. Loading of copper oxide on MCM-41 greatly improved its adsorption capability at elevated temperatures. The influence of the incorporation of copper into MCM-41 samples and the adsorption behavior of these samples are discussed in detail. [source]

A study of copper recovery from copper-contaminated sludge with ferrite and selective leaching processes

ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2007
S.H. Hu
Abstract The purpose of this study was to develop an effective resource recovery and leached residue stabilization process for copper-contaminated sludge. To this end, a treatment procedure utilizing ferrite and selective leaching processes was developed. The XRD examination of ferrite complex revealed the crystalline phases to be mainly Fe3O4, CuO, and 6CuO·Cu2O. A selective leaching process was followed to recover the copper content of the ferrite complex. To promote the dissolution percentage of copper and repress that of iron, additional 0.5 N sulfuric acid was added at intervals to the suspension in the second step of the selective leaching process. The purpose of this operation was to return the suspension pH back to 3 to promote the dissolution of copper oxide and repress the dissolution of iron. Finally, the heavy metal (i.e., Cu, Pb, Cr, and Cd) dissolution of the above residue was examined with toxicity characteristic leaching procedure (TCLP) testing and all met the regulatory standard. © 2007 American Institute of Chemical Engineers Environ Prog 26:104,112, 2007 [source]

Raman spectroscopic analysis of azurite blackening

JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008
E. Mattei
Abstract Azurite is a basic copper carbonate pigment largely employed in painting realization. The areas painted with azurite are easily alterable and are often less resistant than the other parts of artworks. The azurite alteration in a black pigment, the copper oxide (tenorite), has been studied by micro-Raman spectroscopy. The blackening can be due to thermal or chemical alterations: in the second case the alterations being due to the presence of alkaline conditions. Laser-induced degradation of azurite has been studied as a function of the grain size. The results show that the temperature of the grains decreases as the size increases, and azurite degrades into tenorite only below the critical value of 25 µm. To study the chemical alteration of azurite, the pigment has been applied on the plaster of terracotta samples and analyzed at different pH values by micro-Raman spectroscopy. As opposed to most part of the analytical techniques, it can detect the presence of both azurite and tenorite molecules in the same micro areas, and provides a valuable tool to determine azurite degradation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Microstructural Morphology and Electrical Properties of Copper- and Niobium-Doped Tin Dioxide Polycrystalline Varistors

Enhancement of Thermal Conductivity with CuO for Nanofluids

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2006
M.-S. Liu
Abstract The enhancement of the thermal conductivity of ethylene glycol in the presence of copper oxide (CuO) is investigated. CuO nanofluids are prepared in a two-step method. No surfactant is employed as a dispersant. The volume fraction of CuO nanoparticles suspended in ethylene glycol liquid is below 5,vol.-%. The crystalline phases of the CuO powders are measured with x-ray diffraction patterns (XRD). CuO nanoparticles are examined using scanning electron microscopy (SEM) to determine their microstructure. The thermal conductivities of the CuO suspensions are measured by a modified transient hot wire method. The viscosity was measured with a viscosity instrument. The results show that CuO nanofluids with low concentrations of nanoparticles have considerably higher thermal conductivities than the identical ethylene glycol base liquids without solid nanoparticles. The thermal conductivity ratio improvement for CuO nanofluids is approximately linear with the volume fraction of nanoparticles. For CuO nanoparticles at a volume fraction of 0.05 (5,vol-.%) thermal conductivity was enhanced by up to 22.4,%. CuO nanofluids thus have good potential for effective heat transfer applications. [source]

Improving MCM-41 as a Nitrosamines Trap through a One-Pot Synthesis

Evaluation of the sealed-tube low-temperature combustion method for the 13C/12C and 2H/1H ratio determinations of cellulose nitrate

CHINESE JOURNAL OF CHEMISTRY, Issue 11 2001
Fa-Xiang Tao
Abstract Traditionally-suggested combustion time of 1 h at 550°C) with the sealed-tube combustion method for determining the 13C/ 12C ratio of cellulose nitrate or other nitrogen-containing components could produce large negative deviation up to 1°. Three types of cellulose are used to ascertain possible causes. The presence of nitrous oxide (N2O) formed during combustion is most likely responsible for this deviation. Prolongation of the combustion time (at least 5 h at 550°C) and intimate contact between copper oxide and organic matter can greatly improve the analysis precision and effectively reduce this deviation to an acceptable level. Regardless of scattered carbon isotope data, hydrogen isotope data are all reproducible within 2° when this method is coupled with the high temperature uranium reduction method. Thus, care should be taken for determining carbon and nitrogen isotope compositions of nitrogen-containing substances using the low temperature sealed-tube combustion method. [source]

Characterization and Activity of Cu-MnOx/,-Al2O3 Catalyst for Hydrogenation of Carbon Dioxide

CHINESE JOURNAL OF CHEMISTRY, Issue 5 2001
Gong-Xin Qi
Abstract The effect of manganese on the dispersion, reduction behavior and active states of surface of supported copper oxide catalysts have been investigated by XRD, temperature-programmed reduction and XPS. The activity of methanol synthesis from CO2/H2 was also investigated. The catalytic activity over CuO-MnOx/,-Al2O3 catalyst for CO2 hydrogenation is higher than that of CuO/,-Al2O3. The adding of manganese is beneficial in enhancing the dispersion of the supported copper oxide and make the TPR peak of the CuO-MnKx/,-Al2O3 catalyst different from the individual supported copper and manganese oxide catalysts, which indicates that there exists strong interaction between the copper and manganese oxide. For the CuO/,-Al2O3 catalyst there are two reducible copper oxide species; , and , peaks are attributed to the reduction of highly dispersed copper oxide species and bulk CuO species, respectively. For the CuO-MnOx/,-Al2O3 catalyst, four reduction peaks are observed, , peak is attributed to the dispersed copper oxide species; , peak is ascribed to the bulk CuO; , peak is attributed to the reduction of high dispersed CuO interacting with manganese; , peak may be the reduction of the manganese oxide interacting with copper oxide. XPS results show that Cu+ mostly existed on the working surface of the Cu-Mn/,-Al2O3 catalysts. The activity was promoted by Cu with positive charge which was formed by means of long path exchange function between CuOMn. These results indicate that there is synergistic interaction between the copper and manganese oxide, which is responsible for the high activity of CO2 hydrogenation. [source]

Copper Oxide , Graphite Composite Electrodes: Application to Nitrite Sensing

Catalytic effects of copper oxides on the curing and degradation reactions of cyanate ester resin

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007
Shinn-Gwo Hong
Abstract The catalytic effect of copper oxides on the curing and degradation behaviors of the cyanate ester resin is studied with infrared spectroscopy, attenuated total reflection infrared spectroscopy (ATR), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The result of infrared spectroscopy and DSC analyses indicates that accelerated curing effects from different additives are in the order of zinc octoate > cuprous oxide > cupric oxide. The exothermic characteristics of the cyanate ester resin during cure are drastically affected by the presence of the copper oxides. In addition, it is obtained from TGA analyses that the thermal stability and degradation mechanism of cyanate ester resins are also significantly affected by the addition of copper oxides whereas the extent of degradation from the cupric oxide is greater than that from the cuprous oxide. These results are attributed to the differences in catalytic effects and surface areas of two copper oxides on the cyanate ester resin in contact during the thermal exposure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 442,448, 2007 [source]