Electrode copper, iron

Rand, D. A., 1975. Oxygen reduction on sulphide minerals, part III comparisson of activity of various copper, iron, lead, nickle mineral electrodes. Electrochemistry and Interfacial Electrochemistry, 60 265 - 275... 

ELECTRODE. Either ul two substances having different electromotive activity that enables an electric current to flow in the presence of an electrolyte. See also Electrolyte. Electrodes are sometimes called plates or terminal. Commercial electrodes are made uf a number of materials that vary widely in electrical conductivity, i.e.. lead, lead dioxide, zinc, aluminum, copper, iron, manganese dioxide, nickel, cadmium, mercury, titanium, and graphite research electrodes may be calomel mercurous chloride), platinum, glass or hydrogen. 

The choice of cathode materials is less restricted by corrosion considerations than the choice of anodes so few metals react readily with the medium that their use is impractical. Some of the most popular electrode materials are mercury, lead, tin, copper, iron, aluminum, platinum, nickel, and carbon. 

The working electrodes were iron, mild steel, duminum, copper, tin or zinc (polished in water with 1200-grit paper), or 2 to 3 pm zinc-electroplated steel. The counter-electrode was a stainless steel plate and the reference electrode a Tacussel KCl saturated calomel (SCE). The rotating disk electrode was an EDI Radiometer monitored with a CTV 101 Radiometer speed control unit... 

M The tendency to give off metal ions to a solution varies from one metal to another. Therefore, each pair of electrodes wiU build up a characteristic electrochemical potential AV. When unloaded and at standard conditions, the Daniell cell with the electrode parr Zn Cu in a zinc sulphate solution and copper sulphate solution, respectively, has a potential of E = 1.10 volt. If the Cu electrode in the DanieU cell is replaced by an electrode of iron, Fe, immersed in a 1 molar iron sulphate solution, the potential AE = 0.32 volt for the Zn Fe electrode pair can be measured when unloaded. 

The cleaning or depassivation eflect is of great importance in sonoelectrochemistry, as it can be employed to wash off surface-adsorbed species and reduce blocking of the electrode by adsorption of reaction products. This eflect has been reported, for example, for the depassivation of iron electrodes and for the removal of deposits and in the presence of polymer films on the electrode surface. However, damage of the electrode surface, especially for materials of low hardness such as lead or copper, can also occur under harsh experimental conditions and applied intensities [70, Tf, 80]. 

Despite its electrode potential (p. 98), very pure zinc has little or no reaction with dilute acids. If impurities are present, local electrochemical cells are set up (cf the rusting of iron. p. 398) and the zinc reacts readily evolving hydrogen. Amalgamation of zinc with mercury reduces the reactivity by giving uniformity to the surface. Very pure zinc reacts readily with dilute acids if previously coated with copper by adding copper(II) sulphate ... 

Open-Arc Furnaces. Most of the open-arc furnaces are used in melting and refining operations for steel and iron (Fig. 1). Although most furnaces have three electrodes and operate utilizing three-phase a-c power to be compatible with power transmission systems, d-c furnaces are becoming more common. Open-arc furnaces are also used in melting operations for nonferrous metals (particularly copper), slag, refractories, and other less volatile materials. 

Silver [7440-22-4] Ag, as an active material in electrodes was first used by Volta, but the first intensive study using silver as a storage battery electrode was reported in 1889 (5) using silver oxide—iron and silver oxide—copper combinations. Work on silver oxide—cadmium followed. In the 1940s, the use of a semipermeable membrane combined with limited electrolyte was introduced by Andrir in the silver oxide—2inc storage battery. 

Six iron anodes are required for corrosion protection of each condenser, each weighing 13 kg. Every outflow chamber contains 14 titanium rod anodes, with a platinum coating 5 /tm thick and weighing 0.73 g. The mass loss rate for the anodes is 10 kg A a for Fe (see Table 7-1) and 10 mg A a for Pt (see Table 7-3). A protection current density of 0.1 A m is assumed for the coated condenser surfaces and 1 A m for the copper alloy tubes. This corresponds to a protection current of 27 A. An automatic potential-control transformer-rectifier with a capacity of 125 A/10 V is installed for each main condenser. Potential control and monitoring are provided by fixed zinc reference electrodes. Figure 21-2 shows the anode arrangement in the inlet chamber [9]. 

When metals are arranged in the order of their standard electrode potentials, the so-called electrochemical series of the metals is obtained. The greater the negative value of the potential, the greater is the tendency of the metal to pass into the ionic state. A metal will normally displace any other metal below it in the series from solutions of its salts. Thus magnesium, aluminium, zinc, or iron will displace copper from solutions of its salts lead will displace copper, mercury, or silver copper will displace silver. 

Practical examples of using preconcentrating CMEs include the use of a mixed 2,9-dimcthyl-1.10-phenanthrolinc/carbon-pastc electrode for trace measurements of copper (55), the use of clay-containing carbon pastes for voltammetric measurements of iron (56), the use of polyelectrolyte coatings for the uptake and... 

Double layer capacitance of solid at rough electrodes, 52 Double layer parameters, for aluminum, tabulated, 129 and concentration fluctuations, 268, 269 for copper in aqueous solutions, 91 on iron, tabulated, 124... 

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