Effect Of Cathode Material Research Articles

Electrocoagulation and effect of cathode materials on the removal of pollutants from tannery wastewater of Rouïba

The simultaneous removal of organic and inorganic pollutants from tannery wastewater in Rouiba was investigated by electrocoagulation. One liter of effluent was treated by using aluminum and steel cathode and aluminum anodes materials. In the electrocoagulation of the wastewater, the effect of electrolysis time and current density were examined. The results show that aluminum cathode, a current density of 75 A/m 2 in 45 min is the optimal condition for removing pollutants from tannery wastewater. At optimum condition, more than 90% of BOD 5, COD, turbidity, chromium, iron and nitrate were removal. The simulation of results showed a satisfactory fit to the experimental data. In addition, electrocoagulated sludge was analyzed; the results showed the presence of chromium (50%), Total Carbone (15%) and Sulfide (03%) which creates disposal problems.

Electrochemical fluorosulfation of organofluorine compounds

The scope of the review is: the application of fluorosulfonic acid as a solvent and reactant in the organic electrosynthesis, electrochemical behavior of various electrode materials in the fluorosulfonic acid and their effects on the anodic oxidation over wide potential range, the fluorosulfonic acid and its analogs’ adsorption during the anodic oxidation of organofluorine compounds, the effect of cathode material on the fluorosulfonic acid reduction and its influence on the products’ composition at this stage of the reaction. Results of preparative electrosynthesis (direct and indirect fluorosulfation of organofluorine compounds) are discussed, including the reaction mechanisms and the synthesis’ perspectives of the fluorosulfates thus obtained.

The effect of cathode materials on the electrochemical reduction of nitric acid

The effect of cathode materials on the electrochemical reduction of nitric acid Electrochemical or chemical reduction of nitric acid is a well studied area in literature due to the importance of the products formed. The present work focuses on the effect of conventional cathode materials including PbO2, amalgamated Cu, graphite, Pb, Pt and a modified electrode material Ti/TiO2 on the reduction of nitric acid. Ammonia and hydroxylamine are the main products which are estimated by conventional titration methods. Other conditions being similar, the product distribution varies quite drastically as a function of the electrode material and Ti/TiO2 is found to favor a higher ratio of hydroxylamine to ammonia formation compared to other electrodes. The conditions have also been optimized based on the maximum yield of the product.

Electrochemical hydride generation for the determination of hydride forming elements by atomic fluorescence spectrometry

The determinations of As, Bi, Ge, Sb and Se were performed by atomic fluorescence spectrometry following their electrochemical hydride generation. An electrochemical hydride generator based on a screw-thread seal arrangement, working in a continuous flow mode was used. The effects of cathode material, shape and area of material, catholyte, sample flow rate, applied current, catholyte solution concentration and interference of transition metals on signal intensity were studied. Five kinds of materials including lead, graphite, copper, tungsten and platinum with different shapes were tested as cathode materials. The signal obtained from a 3-dimensional electrode was higher than that from a 2-dimensional electrode under the same conditions. The signal intensity of Ge in HNO 3 medium within a narrow concentration range of 0.05–0.10 mol L − 1 was stronger than that in other acidic medium, such as HCl and H 2SO 4. However, the signal intensity of Ge was rapidly decreased with HNO 3, HCl and H 2SO 4 concentration increasing, and then reached approximately zero. In general, limits of detection and a precision were improved using a graphite cathode in H 3PO 4 medium. The analysis of the reference materials showed good agreement with the certified values for As, Bi, Ge, Sb and Se. The method was successfully applied in the determination of As, Bi, Ge, Sb and Se in traditional Chinese medicine samples.

Effect of cathode material on the morphology and photoelectrochemical properties of vertically oriented TiO 2 nanotube arrays

We report, for the first time, on the effect of the cathode material in controlling the morphology and properties of TiO 2 nanotube arrays fabricated by electrochemical anodization of Ti foil in both aqueous and ethylene glycol (EG) electrolytes. Some of the alternative less-expensive cathode materials result in TiO 2 nanotube architectures and photoelectrochemical properties similar to or in some cases superior to those obtained using a Pt cathode.

Low temperature solid oxide fuel cell with Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3 cathode prepared by screen printing

A screen printing technique was developed to deposit Sm 0.2Ce 0.8O 1.9 (SDC) electrolyte films onto NiO/SDC anode substrates. After co-firing the anode/film bilayers at 1400 °C for 4 h, pure Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3 (BSCF), BSCF/SDC and BSCF/Ag were screen-printed onto the sintered SDC films, respectively, to complete the single SOFC fabrication. Impedance measurements show that the area-specific resistance (ASR) for BSCF, BSCF/Ag and BSCF/SDC is 0.08, 0.12 and 0.22 Ωcm 2 at 600 °C, respectively. The cell with pure BSCF cathode provides a maximum power density of 1.08 Wcm − 2 at 600 °C using hydrogen as fuel and stationary air as oxidant. The cells with BSCF/SDC and BSCF/Ag composite cathodes give the maximum power densities of 0.54 and 0.59 Wcm − 2 at 600 °C, respectively. The results indicate that the SOFCs with BSCF-based cathodes show excellent performance below 600 °C. Screen printing is a promising approach for thin electrolyte film fabrication. The effect of cathode materials on the cell performance is electrochemically tested and discussed.

Effect of cathode material on production of electrolytic copper powder : R. Jonovic et al.. (Bor Copper Inst, Bor, Serbia [F R Yugoslavia].)

Effect of cathode material on production of electrolytic copper powder : R. Jonovic et al.. (Bor Copper Inst, Bor, Serbia [F R Yugoslavia].)

High Performance Cell Development Using Scandia Doped Zirconia Electrolyte for Low Temperature Operating SOFCs

The Sc 2 O 3 -ZrO 2 system, which has higher electrical conductivity compared to the Y 2 O 3 -ZrO 2 system, was examined for electrolyte component of the planar type SOFC. For low temperature operation, the effect of cathode material and Sc 2 O 3 dopant concentration in electrolyte were investigated; maximum power density of 0.6 W/cm 2 was obtained for electrolyte-supported cells using humidified H 2 as fuel and air as oxidant at 800°C. Furthermore, the maximum power density of 2.4 W/cm 2 was obtained for anode-supported cells in humidified H 2 as fuel and O 2 as oxidant at 800°C.

Electrochemical Synthesis of Cyanoacetic Acid from Chloroacetonitrile and Carbon Dioxide

The electrochemical carboxylation of chloroacetonitrile was investigated in dimethylformamide (DMF) and acetonitrile (MeCN) by cyclic voltammetry and controlled-potential electrolysis. Both direct electroreduction and mediated reduction of the halide in -saturated solvents were used to achieve the electrocarboxylation process. Also the effects of cathode material and cell type (divided or undivided with dissolving anode) were examined. In DMF the electrolyses performed in the divided cell resulted in low to moderate yields of (25-45%), independent of the electrode material and catalyst type. The process is remarkably more efficient in MeCN, in which acid yields of ca. 60% were obtained under similar conditions. Very good results were obtained in both solvents when an undivided cell with aluminum sacrificial anode was used. In this case, the acid yield increased to 73 and 93% in DMF and MeCN, respectively. © 2002 The Electrochemical Society. All rights reserved.

Effects of cathode materials and arc current on optimal bias of a cathodic arc through a magnetic duct

A negatively biased collecting plate was used to collect the ion current of the cathodic arc plasma transported through a curved magnetic duct. The optimal duct bias at which the duct has the maximum efficiency for plasma transport was measured for C, Ti, Mo, and W plasmas as a function of the arc current and guiding magnetic field. The optimal bias decreased with the magnetic field and was almost steady when the field was above 400 G. The optimal bias at 400 G and above increased with the arc current for C plasma but the opposite relationship was observed for Ti, Mo, and W plasmas. The effects of the plasma density, ion mass, ion kinetic energy, and magnetic field on the optimal bias are discussed.

Effect of cathode material on the opening performance of microsecond-conduction-time plasma opening switch

Experiments were conducted to investigate the effect of cathode material on the opening performance of microsecond-conduction-time plasma opening switch with cathode made of aluminum, stainless steel, molybdenum and tungsten. Remarkably different opening characteristics have been shown for these materials, with tungsten or molybdenum corresponding to better opening performance than aluminum or stainless steel. Heuristic physical explanations are proposed for understanding the switch behavior.

Cathodic reduction of 4-nitroso-N,N-dimethylaniline at various electrode materials

This study is concerned with the cathodic reduction of 4-nitroso-N,N-dimethylaniline to 4-amino-N,N-dimethylaniline in 1.0 M HCl and 1.0 M H2SO4 containing 10% MeOH. The effect of cathode material, supporting electrolyte, electroactive compound concentration, temperature and current density in the electrochemical synthesis of 4-amino-N,N-dimethylaniline were investigated. The best cathode material was tin, which gave a selectivity of 92.7% with a current yield of 90.3% at a current density of 6 mA cm−2. The final electrolysis product was obtained as its respective HCl and H2SO4 salts and their structures were elucidated using spectrochemical techniques.

Electrolytic Reduction of CCl4—Effects of Cathode Material and Potential on Kinetics, Selectivity, and Product Stoichiometry

Carbon tetrachloride (CCl4) was reductively transformed via electrolysis at metal cathodes consisting of pure Ag, Al, Au, Cu, Fe, Ni, Pd, and Zn. Primary products included CHCl3, CH2Cl2 and CH4. Traces of CH3Cl, C2H4, C2H6, C3H8, and other unidentified products were also observed in headspace samples. CHCl3 was reduced to CH2Cl2 and CH4 under the same experimental conditions, although at a slower rate. CH2Cl2 was essentially stable during the course of these experiments (ks < 0.05 L/m2 · min). CCl4 reduction was first order in the bulk liquid phase concentration. Pseudo-first-order rate constants were a function of cathode material, pH, and applied cathode potential (Ec) in the range −1.4 V ≤ Ec ≤ −0.4 V vs. SHE. At all electrodes, reaction rates conformed to Butler-Volmer kinetics, modified to account for mass transfer limitations. Under comparable conditions, the kinetics of CCl4 electrolysis at Ni and Cu electrodes were superior to those of transformation using any other metal tested. At Ec = −0.6 and −0.8 V, rate constants for CCl4 reduction at a Cu electrode decreased with increasing pH in the range 2 < pH < 6. At Ec ≤ −1.2 V, reduction was limited by mass transfer to the electrode surface and was independent of cathode material and pH. Electrode efficiency (ratio of dehalogenation rate to total electrolytic current) for CCl4 reduction was inversely related to the material-dependent exchange current density for hydrogen gas generation, suggesting that production of H2 (g) is the most significant competitive reaction under the conditions of the experiments. Based on efficiency considerations, the electrode materials were ordered Zn > Cu > Fe > Ni. Key words: Reductive dehalogenation; carbon tetrachloride; groundwater remediation; electrolysis

Electrochemical reduction of nitroaromatics to anilines in basic media: effects of positional isomerism and cathode composition

This laboratory has previously reported a high yield synthesis of 3-amino-4-hydroxybenzoic acid via electrochemical reduction of the corresponding nitroaromatic in basic medium at a copper cathode. The scope of reaction in basic medium, the effects of cathode material, and several electrochemical parameters have been investigated and a mechanistic hypothesis is proposed. We report here that certain classes of ortho/para-substituted nitroaromatics give good yields of the corresponding anilines in base, especially when reduced at copper. High current densities (>>20 mA/cm{sup 2}) can be utilized to make this a practical synthetic procedure for consideration as more than a laboratory curiosity.

Effect of cathode material on the initial stage of copper deposition

The effect of various cathode materials on the crystallization of copper out of a sulfate electrolyte under galvanostatic conditions was studied. A single pulse potentiostatic circuit was used. Oscillographs for the deposition of copper on a graphite and a lead cathode at various densities are given. Results demonstrated that cathode materials having the highest overvoltage to copper ions, such as niobium, tantalum, or lead, were the most effective in enhancing deposition.

Investigations into the effect of cathode material on temperature distribution during electrochemical machining

SUMMARY Electrochemical machining (ECM) is one of the most widely used unconventional manufacturing processes. Its capabilities have not been fully exploited mainly because of some inherent problems associated with tool design. Most of the models available for tool design in ECM ignore the effect of the heat transferred through the cathode and anode and its effects on the variation of different process parameters during ECM. In the present paper, a simple thermal-resistance model of the ECM process is proposed. Using this model, the effects of the heat transferred through electrodes on temperature distribution, electrolyte conductivity, anode profile, metal removal rate (MRR), etc. have been studied. The experimental data have then been used to test the accuracy of the model. The tests show that, for accurate determination of the anode profile, any model which takes no account of the heat transferred through the electrodes will yield erroneous results.

Determination of trace elements in seawater by neutron activation analysis and electrochemical separation

The combination of neutron activation analysis and electrolysis at a constant, controlled potential has proved itself to be a useful multielement method for the determination of 28 elements in seawater. After freeze-drying and irradiation, the samples are dissolved and electrolyzed for 1 h. The radioactive species deposited on the mercury cathode allow determination of 14 elements (Ag, As, Au, Cd, Co, Cr, Fe, Ga, Hg, La, Mo, Sb, Se, Zn). Another 14 elements (Ba, Br, Ca, Ce, Cs, Eu, Na, Rb, Sc, Sm, Sr, Th, U, Yb) are quantitatively determined by measuring the activities in the residual solution. To obtain a reproducible electrolysis, radioactive tracers have been used to study the decrease of element concentrations in solution as a function of time of electrolysis, the influence of the initial element concentration on the rate constant k, the effect of cathode material and of the pH in the solution. 4 figures, 4 tables.

The effect of cathode materials on reactive ion etching of silicon and silicon dioxide in a CF4 plasma

Silicon and silicon dioxide have been Reactive Ion Etched in a CF4 plasma using a diode sputtering configuration to achieve etching. Pressures ranged from 20 to 100 millitorr and power densities to the RF cathode were between 0.1 and 1.0 W/cm2. The effect of cathode material on the quality of etched surfaces and on etch rates has been investigated. It has been observed that the etch rate of silicon decreases as the area of silicon exposed to the plasma is increased and that this silicon loading effect is strongly influenced by the material covering the balance of the cathode. For instance, the silicon loading effect is much more pronounced when silicon dioxide rather than aluminum is used to cover the balance of the cathode. This silicon loading effect was investigated further by varying RF power. It was found that loading a silicon dioxide covered cathode with silicon wafers decreases the dependence of silicon etch rate on power. The silicon dioxide etch rate and its dependence on RF power are the same whether silicon, silicon dioxide or aluminum is used to cover the balance of the cathode. Possible explanations for these experimental results will be discussed.

Laboratory Studies of Galvanic Corrosion I. Two-Metal Couples

Abstract Galvanic interaction of stainless steel 304L, Ni 270, Cu, Ti-6AI-4V, Sn, 4130 steel, Cd, and Zn has been studied in 3.5% NaCl using galvanic current and weight loss measurements in 24-hour tests. Galvanic couples of 4130 steel and one of the Al alloys 1100, 2024, 2213, 6061, and 7075 have also been evaluated in tap water and distilled water. Galvanic current data can be used to assess both the effect of different dissimilar cathode materials as well as the relative susceptibility to galvanic corrosion of anode materials. For 3.5% NaCl, it has been found that the effect of the cathode material decreases in the order Cu &amp;gt; Ni &amp;gt; stainless steel &amp;gt;Ti-6Al-4V, while the relative susceptibility of anode materials decreases in the order Sn &amp;gt; Zn &amp;gt; 4130 steel &amp;gt; Cd. An analysis of data in various electrolytes shows that coupling of 4130 steel to Al alloys leads to cathodic protection of the steel in 3.5% NaCl, but to accelerated corrosion in tap water and distilled water.

The determination of boron in solution to sub-p.p.b. concentrations by hollow-cathode emission

The determination of boron in solutions to sub-p.p.b. concentrations by hollow-cathode emission is demonstrated. The effects of cathode material, clean-up procedure, fill gas, and tube current were investigated to determine the conditions yielding optimal sensitivity. The boron atomic line emission is 200 times as intense as boron oxide band emission.