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Articles 241 - 261 of 261

Full-Text Articles in Nanoscience and Nanotechnology

Characterisation Of Non-Condensable Sulphur Containing Gases From Kraft Pulp Mills (2), João F. Gomes Jan 2001

Characterisation Of Non-Condensable Sulphur Containing Gases From Kraft Pulp Mills (2), João F. Gomes

João F Gomes

This paper describes work performed on the sampling and analysis of non-condensable gases (NCG) emitted from diffuse sources of a Portuguese Kraft pulp mill, which is the background information for a NCG collection, treatment and disposal system. The variability found in the composition of the gaseous compounds showed the existence of gaseous streams other than typical total reduced sulphur (TRS) compounds as usually described. From the measured TRS concentrations and the gas flow rate from each source it was possible to calculate the emission flow rate, E, of each source. These emission flow rates were then divided into 3 categories …

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Template Synthesis Of Nano-Structured Electrode Materials And Its Electrochemical Performance, Jian Zhao, Quan Yong Gao, Yong Yang, Zu-Geng Lin Nov 2000

Template Synthesis Of Nano-Structured Electrode Materials And Its Electrochemical Performance, Jian Zhao, Quan Yong Gao, Yong Yang, Zu-Geng Lin

Journal of Electrochemistry

In this letter, various nano structured materials such as spinel LiMn 2O 4 nanotubes/nanowires and carbon nanotubes have been prepared by using porous alumina template. The prepared template and materials have been characterized by AFM and TEM techniques. It is shown that size of the nanotubes can be conveniently controlled by using template method. Some preliminary results of cyclic voltammetry about nano structured LiMn 2O 4 are also reported.

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Studies Of Adsorption And Oxidation Of Ethanol On Nm-Pt/Gc Electrode——I.Cyclic Voltammograms And In-Situ Ftir Spectroscopy In Alkaline Media, Guo-Lian Chen, Shi-Gang Sun, Sheng-Pei Chen, Zhi-You Zhou Nov 2000

Studies Of Adsorption And Oxidation Of Ethanol On Nm-Pt/Gc Electrode——I.Cyclic Voltammograms And In-Situ Ftir Spectroscopy In Alkaline Media, Guo-Lian Chen, Shi-Gang Sun, Sheng-Pei Chen, Zhi-You Zhou

Journal of Electrochemistry

The electro_oxidation of ethanol on nm_Pt/GC electrode in alkaline solutions containing 0.02 mol·L -1 NaOH+0.1 mol·L -1 CH 3CH 2OH was investigated by using cyclic voltammetry and in_situ FTIR spectroscopy. The experimental results demonstrated that the main product of ethanol oxidation is CH 3COO -,only very small amount of CH 3CHO has been determined simultaneously. In contrast with the dual path reaction mechanism for the oxidation of ethanol in acid media,the oxidation of ethanol in alkaline media didn't pass through the dissociative adsorption,and no adsorbed species could be determined even using a nm_Pt/GC electrode that gives rise to enhancement of …

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Template Synthesis And Uv-Vis Absorption Spectra Of The Nanowire Arrays Of Cadmium Chalcogenides May 2000

Template Synthesis And Uv-Vis Absorption Spectra Of The Nanowire Arrays Of Cadmium Chalcogenides

Journal of Electrochemistry

XU Shi_min, XUE Kuan_hong , KONG Jing_lin, SUN Dong_mei, FENG Yu_ying, LU Hai_yan (Dept. of Chem., Nanjing Normal Univ., Nanjing 210097, China) WANG Guang_hou (National Laboratory of Solid State Microstructures, Nanjing Univ., Nanjing 210093, China)The porous alumina membrane formed in the anodic oxidation of highly pure aluminum foil has attracted a great deal of attention in recent years [1] . It can be served as a desired template to prepare nanometer scale materials [2] due to its unique structure of discrete and cylindrical nanopores, paralleled one another, with the homogeneous size and distribution [3] . Chalcogenide semiconductors have promising prospect …

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Studies Of Electrochemical Characteristics Of Pasted Nickel Hydroxide Electrode With Surface Deposited Cobalt, Xianyou Wang, Yunshi Zhang, Jie Yan, Zheng Zhu, Huatang Yuan, Deying Song Feb 1999

Studies Of Electrochemical Characteristics Of Pasted Nickel Hydroxide Electrode With Surface Deposited Cobalt, Xianyou Wang, Yunshi Zhang, Jie Yan, Zheng Zhu, Huatang Yuan, Deying Song

Journal of Electrochemistry

The surface of the spherical nickel hydroxide particles used as an active material in pasted nickel electrodes is surface_deposited with cobalt. This paper investigated the effects of the amount of cobalt deposit on the characteristics of nickel hydroxide electrode. The performances of the electrode, such as discharge capacity, utilization of active material and reversibility of Ni(OH) 2/NiOOH redox reaction, were studied by comparing the charging/discharging curves and cyclic voltammograms. The mechanism of action of cobalt deposits has been described in terms of the electrochemical impedance spectroscopy of nickel hydroxide electrode.

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Practical Determination Of Efficiency Of Electrostatic Precipitators, João F. Gomes Jan 1999

Practical Determination Of Efficiency Of Electrostatic Precipitators, João F. Gomes

João F Gomes

Electrostatic precipitators are one of the most efficient particulate pollution control equipments used mainly for the treatment of gaseous effluents at high flow rates. Consequently electrostatic precipitators are widely used in thermal power plants, cement plants and pulp mills. Apart from a high efficiency other advantages are related with the fact that this type of equipment has a considerable low payback time in industrial plants where the particulate recovered from the gases has commercial value and can be recycled within the industrial process itself or even sold to other industrial companies. Where sulphate (Kraft) pulp mills are concerned an electrostatic …

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Drect Electro_Oxidation Synthesis Of D Arabinose On Spectroscopic Graphite Electrode, Hei Wei, Huang Ying Nov 1998

Drect Electro_Oxidation Synthesis Of D Arabinose On Spectroscopic Graphite Electrode, Hei Wei, Huang Ying

Journal of Electrochemistry

D Arabinose synthesized by direct electro_oxidative decarboxylation of D gluconate on graphite electrode from aqueous solutions. The effects of D gluconate concentration, electrolysis potential, temperature and electrolyte composition on the current efficiency and product yield of electrosynthsis are discussed. The laboratory scale electrosynthesis was achieved with flow through cell.The optimum technology conditions for electrosynthesis were obtained with orthogonal design method.Both galvanostatic and potentionstatic conditions have been exploited, the later was found to be more effective.

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Studies Of Surface Alloy As High Efficient Electrocatalyst For Glyoxylic Acid Synthesis, Shengpei Chen, Shengqing Xia, Shigang Sun May 1998

Studies Of Surface Alloy As High Efficient Electrocatalyst For Glyoxylic Acid Synthesis, Shengpei Chen, Shengqing Xia, Shigang Sun

Journal of Electrochemistry

No abstract provided.

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InSitu Raman Spectroscopic Study Of The Oxidation And Reduction Of Ag Electrode In Na_2so_4 Solution, Chen Y X, Huang K Q, Tian Z Q May 1998

InSitu Raman Spectroscopic Study Of The Oxidation And Reduction Of Ag Electrode In Na_2so_4 Solution, Chen Y X, Huang K Q, Tian Z Q

Journal of Electrochemistry

Insitu Raman spectroscopy combined with cyclic voltammogram measurements was used to investigate formation of oxygen species at Ag electrode surfaces during the oxidation and reduction process in 0.1 mol/L Na_2SO_4 solution. The time dependent Raman spectra show that at potentials positive of 0.2 V, adsorption of oxygen atom occurs, while at the potentials positive of 0.4 V, some oxygen atoms migrate into subsurface of the Ag electrode and the other form strongly bound oxygen on the surface through chemical bond. At the same potentials, part of the silver atoms are oxidized and form Ag_2SO_4. During the negative potential ex cursion, …

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Progresses In Surface Electrochemistry And Electrocatalysis ——A Review On The 1997 Joint International Meeting Of Electrochemistry And 97′ International Meeting Of Surface Electrochemistry, Shigang Sun Feb 1998

Progresses In Surface Electrochemistry And Electrocatalysis ——A Review On The 1997 Joint International Meeting Of Electrochemistry And 97′ International Meeting Of Surface Electrochemistry, Shigang Sun

Journal of Electrochemistry

The progresses in surface electrochemistry and electrocatalsis reported in the 1997 joint international meeting of electrochemistry and in the 97′ international meeting of surface electrochemistry were reviewed. The main trends described in this paper consisted of 7 aspects: 1) the studies employing single crystal electrodes, 2) the development of in situ methods of diverse spectroscpoy, 3) the innovation of new research techniques, 4) the preparaton of electrocatalyst of high performances, 5) the quantitative studies on kinetics of electrocatalytic reactions, 6) the investigation on the dynamic processes of surface by timeresolved methods, and 7) the theoretical modeling and simulation of surface …

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Studies Of Surface Electrochemistry And Electrocatalysis At Atomic And Molecule Level, Shigang Sun Feb 1998

Studies Of Surface Electrochemistry And Electrocatalysis At Atomic And Molecule Level, Shigang Sun

Journal of Electrochemistry

The main progresses achieved during last few years in our research group concerning studies of surface electrochemistry and electrocatalysis were reviewed in this present paper. Four topics were described: 1) the surface electrochemistry and model electrocatalysis of metal single crystal planes, 2) the electrocatalytic reaction mechanism and the control of reaction pathways at molecule level, 3) the reaction kinetics of electrooxidation of small organic molecules, and 4) the relationship between the properties and the surface chemical states of electrocatalyst. This review lays in emphasis on the demonstration of the results as well as the research direction of surface electrochemistry and …

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The Investigations Of Surface Treatment Methods And Characterization Of Oxide Films On Ab_5Based Metal Hydride Electrodes Ⅰ. New NiRich Treatment Methods And Photoelectrochemical Characterization Of Oxide Films, Junmin Nan, Yong Yang, Jun Li, Zugeng Lin Feb 1998

The Investigations Of Surface Treatment Methods And Characterization Of Oxide Films On Ab_5Based Metal Hydride Electrodes Ⅰ. New NiRich Treatment Methods And Photoelectrochemical Characterization Of Oxide Films, Junmin Nan, Yong Yang, Jun Li, Zugeng Lin

Journal of Electrochemistry

Two simple and efficient surface treatment methods for AB_5type hydrogen storage alloys were developed. The results of X-ray photoelectron spectroscopy (XPS) and cyclic voltammetric (CV) experiments showed that the hydrogen storage alloys treated by two different methods had Nirich surface layer so that the performances of the electrodes were improved after treatment. The characterization of the oxide films which formed on the surface of electrodes through potentiodynamic oxidation with the help of photoelectrochemical microscopy (PEM) were done. The anodic photocurrent and the cathodic photocurrent related to the oxidation of hydrogen and the reduction of oxygen on the surface layer were …

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Characterisation Of Non-Condensable Sulphur Containing Gases From Kraft Pulp Mills, João F. Gomes Jan 1998

Characterisation Of Non-Condensable Sulphur Containing Gases From Kraft Pulp Mills, João F. Gomes

João F Gomes

This paper describes work performed on the sampling and analysis of non-condensable gases (NCG) emitted from diffuse sources of a Portuguese kraft pulp mill, which is the background information for a NCG collection, treatment and disposal system. The variability found in the composition of the gaseous compounds showed the existence of gaseous streams other than typical total reduced sulphur (TRS) compounds as usually described.

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A Simple Way To Measure Particle Size, João F. Gomes Jan 1998

A Simple Way To Measure Particle Size, João F. Gomes

João F Gomes

The size range of particles is an important parameter for subsequent dispersion estimates and sometimes is quite useful for analysing the performance of combustion equipment as well as dedusting equipment efficiency. So far, no standard method has been developed but several laboratories use laser-beam techniques which are usually quite expensive ones. In this paper a method is presented where the particles are collected isokinetically in a filter from gases circulating in a stack as described in USEPA method 5. Afterwards particles are observed at an optical microscope and measured. In spite of some limitations this appears to be an inexpensive …

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Assessment Of Opacimeter Calibration On Kraft Pulp Mills, João F. Gomes Dec 1997

Assessment Of Opacimeter Calibration On Kraft Pulp Mills, João F. Gomes

João F Gomes

This paper describes the methodology and specific techniques for calibrating automatic on-line industrial emission analysers, specifically equipments that measure total suspended dust installed in pulp mills within the scope of Portuguese Regulation Nº 286/93 on air quality. The calibration of opacimeters is a multi-parameter relationship instead of the bi-dimensional calibration which is used in industrial practice. For a stationary source from a pulp mill such as the recovery boiler stack, which is subjected to significant variations, the effects of parameters such as the humidity and gas temperature, deviations on isokinetism, size range of particles and characteristic transmitance of equipment are …

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Surface Modification Of Molten Carbonate Fuel Cell Anode, Baizeng Fang, Xinyu Liu, Xindong Wang, Shuzhen Duan May 1997

Surface Modification Of Molten Carbonate Fuel Cell Anode, Baizeng Fang, Xinyu Liu, Xindong Wang, Shuzhen Duan

Journal of Electrochemistry

In this study, the anode material of molten carbonate fuel cell was modified by the deposition of niobium on nickel surface. The results of polarization experiments reveal that the corrosion resistant properties as well as electrocatalytic activity have been improved greatly.

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Pollutant Atmospheric Emissions From Portuguese Kraft Pulp Mills, João F. Gomes Jan 1997

Pollutant Atmospheric Emissions From Portuguese Kraft Pulp Mills, João F. Gomes

João F Gomes

This paper describes systematic work done in the field of atmospheric emissions from Portuguese Kraft pulp mills. This study led to the determination of emission factors from stationary sources that proved to be an important tool to assess the need for investment on air pollution abatement equipment.

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Surface Modifications Of Carbon Materials Used As Anode Of Lithium Ion Battery Ⅰ.Influences Of Oxidation And Reduction Pretreatment On Anode Performance, Shuhua Ma, Hanju Guo, Ji Li, Hongze Liang, Xiabin Jing, Fosong Wang Nov 1996

Surface Modifications Of Carbon Materials Used As Anode Of Lithium Ion Battery Ⅰ.Influences Of Oxidation And Reduction Pretreatment On Anode Performance, Shuhua Ma, Hanju Guo, Ji Li, Hongze Liang, Xiabin Jing, Fosong Wang

Journal of Electrochemistry

The influences of the trace oxygen containing functional groups on surface of carbon material on cell performance of carbon anode for lithium ion batteries were studied by means of the pretreament in various oxidant/reductant systems.The results showed that the rich oxygen containing functional groups impaired the cell performance of carbon material anode,and the reduction of these groups in quantity and oxidation degree can increase charge/discharge capacity and improve first charge/discharge efficiency.The reason was also discussed in the light of effects of surface organic groups on decomposition reactivity of electrolyte and formation process of surface passivating film.

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The Reduction Of Oxygen To Hydrogen Peroxide In An Acidic Trickle Bed Cell Using Graphite Chip Cathode, Zhaoe Lu, Guanyong Zhang, Tiangeng Zhong, Guonu Fang May 1996

The Reduction Of Oxygen To Hydrogen Peroxide In An Acidic Trickle Bed Cell Using Graphite Chip Cathode, Zhaoe Lu, Guanyong Zhang, Tiangeng Zhong, Guonu Fang

Journal of Electrochemistry

The authors investigated the electrochemical reduction of oxygen to hydrogen peroxide in 0.05 mol/L H 2SO 4 solution by the trickle bed electrode using graphite chip. The bed dimension was 14×5×0.6 cm. The current efficiency and the concentration of H 2O 2 in the catholyte were determined at various current strengths and various rates of adding the electrolyte. The proper current was 0.15 A. i.e. the current density was 2.1 mA/cm 2 vertical cross section area of the bed. The concentration of H 2O 2 reached 7×10 -3 mol/L with the current efficiency of 0.2. If the concentration of H …

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Notice On A Method For Measuring Size Range Of Particles In Gases From Stationary Sources, João F. Gomes Jan 1990

Notice On A Method For Measuring Size Range Of Particles In Gases From Stationary Sources, João F. Gomes

João F Gomes

No abstract provided.

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Program Calculates Critical Properties, João F. Gomes Jan 1988

Program Calculates Critical Properties, João F. Gomes

João F Gomes

No abstract provided.

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