Electrolytic electrolyte baths

Crude lead contains traces of a number of metals. The desilvering of lead is considered later under silver (Chapter 14). Other metallic impurities are removed by remelting under controlled conditions when arsenic and antimony form a scum of lead(II) arsenate and antimonate on the surface while copper forms an infusible alloy which also takes up any sulphur, and also appears on the surface. The removal of bismuth, a valuable by-product, from lead is accomplished by making the crude lead the anode in an electrolytic bath consisting of a solution of lead in fluorosilicic acid. Gelatin is added so that a smooth coherent deposit of lead is obtained on the pure lead cathode when the current is passed. The impurities here (i.e. all other metals) form a sludge in the electrolytic bath and are not deposited on the cathode. 

According to Faraday s law, one Faraday (26.80 Ah) should deposit one gram equivalent (8.994 g) of aluminum. In practice only 85—95% of this amount is obtained. Loss of Faraday efficiency is caused mainly by reduced species ( Al, Na, or A1F) dissolving or dispersing in the electrolyte (bath) at the cathode and being transported toward the anode where these species are reoxidized by carbon dioxide forming carbon monoxide and metal oxide, which then dissolves in the electrolyte. Certain bath additives, particularly aluminum fluoride, lower the content of reduced species in the electrolyte and thereby improve current efficiency. 

Oxidative surface treatment processes can be gaseous, ie, air, carbon dioxide, and ozone Hquid, ie, sodium hypochlorite, and nitric acid or electrolytic with the fiber serving as the anode within an electrolytic bath containing sodium carbonate, nitric acid, ammonium nitrate, ammonium sulfate, or other electrolyte. Examples of electrolytic processes are described in the patent Hterature (39,40)... 

Early in their work on molten salt electrolytes for thermal batteries, the Air Force Academy researchers surveyed the aluminium electroplating literature for electrolyte baths that might be suitable for a battery with an aluminium metal anode and chlorine cathode. They found a 1948 patent describing ionically conductive mixtures of AICI3 and 1-ethylpyridinium halides, mainly bromides [6]. Subsequently, the salt 1-butylpyridinium chloride/AlCl3 (another complicated pseudo-binary)... 

The electrolytic bath consists of two compartments, anodic and cathodic. In the first,... 

They concluded, thereby, that Ag2Te formation is governed by the initial amount of silver deposit. It is worth noting that the present method, involving dilute electrolytic baths of the compound precursors, deviates from the typical, initially proposed by Panicker et al., method of employing high concentration ratios of the metal to the chalcogen precursor. 

Salt bath descaling is the process of removing surface oxides or scale from a workpiece by immersion of the workpiece in a molten salt bath or a hot salt solution. The workpiece is immersed in the molten salt [temperatures range from 400°C to 540°C (750-1000°F)], quenched with water, and then dipped in acid. Oxidizing, reducing, and electrolytic baths are available, and the particular type needed depends on the oxide to be removed. 

The composition of the codeposition bath is defined not only by the concentration and type of electrolyte used for depositing the matrix metal, but also by the particle loading in suspension, the pH, the temperature, and the additives used. A variety of electrolytes have been used for the electrocodeposition process including simple metal sulfate or acidic metal sulfate baths to form a metal matrix of copper, iron, nickel, cobalt, or chromium, or their alloys. Deposition of a nickel matrix has also been conducted using a Watts bath which consists of nickel sulfate, nickel chloride and boric acid, and electrolyte baths based on nickel fluoborate or nickel sulfamate. Although many of the bath chemistries used provide high current efficiency, the effect of hydrogen evolution on electrocodeposition is not discussed in the literature. 

The electrodeposited Bi2Sr2CaiCu2Ox (BSCCO) precursor films were obtained by co-electrodeposition of the constituent metals using nitrate salts dissolved in DMSO solvent. The electrodeposition was performed in a closed-cell configuration at room temperature ( 24°C). The cation ratios of the electrodeposition bath were adjusted systematically to obtain BSCCO precursor compositions. A typical electrolyte-bath composition for the BSCCO films consisted of 2.0-g Bi(N03)3-5H20,1.0-g Sr(N03)2, 0.6-g Ca(N03)2-4H20, and 0.9-g Cu(N03)2-6H20 dissolved in 400 mL of DMSO solvent. The substrates were single-crystal LAO coated with 300 A of Ag. 

Figure 17.2. Current versus potential for a two (double)-electrolyte bath.

BLM, the type and concentrations) of the electrolytes bathing the BLM, the ions adsorbed on the BLM surface, and the extent to and frequency with which the BLM is bent [419]. These experimental observations have led to a phenomenological definition of the flexoelectric coefficient, f, as the ratio between the bending-induced transmembrane potential, Uf, and the change of curvature, c, that accompanies the bending of the membrane ... 

For the implementation both companies bought an Ampere-hour equipment and installed a dosage for the brighteners in the electrolytic bath. 

Fig. 19. An emf of about 25 mV exists between titanium and TiNi electrodes at temperatures above TTR. A TiNi wire coiled outside the electrolytic bath below TTR. When this coiled wire is inserted into the bath at temperature above TTR the wire will instantly straighten out due to memory effect. By letting the uncoiling TiNi wire to come in contact with the TiNi electrode, an emf of more than 500 mV is registered.- reference [49],...

Cathodic reduction is also used to purify some metals, such as copper. Slabs of impure copper serve as the anode, while a pure copper sheet serves as the cathode in an undivided electrolytic cell. The electrolytic bath is copper(II) sulfate. During electrolysis, Cu2+ ions leave the anode and plate on the cathode. Impurity metals more reactive than copper are oxidized and stay in solution. Less reactive metals collect at the bottom of the cell. After about a month, the enlarged copper cathodes are removed (Ebbing and Gammon, 2005). Metals can also be oxidized electrolytically at the anode (anodized). It is even possible to further oxidize some metals in a low oxidation state to a higher oxidation state. 

The possibility of the free suspension of the electrodes in a vessel is of great help in metallurgical refining processes where both anodes and cathodes have to be periodically removed from the electrolytic bath and replaced. 

Pulvermacher s chain — This was a -> battery consisting of copper and zinc wires wound around pencil-like wooden sticks, and the sticks connected in a chainlike manner. The wooden sticks were soaked with dilute acetic acid, so that the chain produced electricity also when removed from an electrolyte bath. The chain was used in galvanic therapy. 

If the conductance of the electrolyte is low, the current lines will tend to concentrate on the parts of the cathode nearest the anode and the throwing power will be bad. With a solution of good conductance, however, there will be no particular preference, as far as this factor is concerned, for one portion of the cathode over any other high conductance will thus improve throwing power. The conductance of an electrolytic bath is generally so good, however, that there is no noticeable influence on the throwing power. 

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