Diaphragm cells cathode compartment

Fig. 10 Examples of parallel-plate and frame designs for laboratory flow-through cells (a) cell chamber for strong mixing and (b) various parts of a cylindrical cell. A anode (with preelectrode) G sealing gaskets AC anode compartment (glass ring, reduced mixing requirements) M membrane (diaphragm) CC cathode compartment (three tubes for gas outlet, sufficient mixing by gas evolution) C cathode (current feeders outside the cell at the four corners).

Nickel. Most nickel is also refined by electrolysis. Both copper and nickel dissolve at the potential required for anodic dissolution. To prevent plating of the dissolved copper at the cathode, a diaphragm cell is used, and the anolyte is circulated through a purification circuit before entering the cathodic compartment (see Nickel and nickel alloys). 

Electrochemical Generation of Chlorine Dioxide from Chlorite. The electrochemical oxidation of sodium chlorite is an old, but not weU-known method of generating chlorine dioxide. Concentrated aqueous sodium chlorite, with or without added conductive salts, is oxidized at the anode of an electrolytic cell having a porous diaphragm-type separator between the anode and cathode compartments (122—127). The anodic reaction is... 

Diaphrag m Cell Technology. Diaphragm cells feature a porous diaphragm that separates anode and cathode compartments of the cell. Diaphragms should provide resistance to Hquid flow, requite minimum space between anode and cathode, produce minimum electrical resistance, and be durable. At the anode, which is generally a DSA, chloride ions are oxidized to chlorine (see eq. 1) and at the cathode, which is usually a woven steel wine mesh, water is reduced to hydrogen. 

In the membrane process, the chlorine (at the anode) and the hydrogen (at the cathode) are kept apart by a selective polymer membrane that allows the sodium ions to pass into the cathodic compartment and react with the hydroxyl ions to form caustic soda. The depleted brine is dechlorinated and recycled to the input stage. As noted already, the membrane cell process is the preferred process for new plants. Diaphragm processes may be acceptable, in some circumstances, but only if nonasbestos diaphragms are used. The energy consumption in a membrane cell process is of the order of 2,200 to 2,500 kilowatt-hours per... 

In order to provide for purification of the electrolyte, diaphragm cells are used to form separate anode and cathode compartments, and the anodes are encased in loose-fitting, open-weave bags to facilitate the removal of slime with the anodes. The anolyte is continuously taken out, purified and fed into the cathode compartments where nickel electrodeposits on the cathodes. A small hydrostatic head of purified electrolyte in the cathode compartment is maintained in order to prevent the diffusion of anolyte with its impurities into the cathode compartments. 

This process not only produces chlorine, it is also a way in which enormous quantities of sodium hydroxide are produced with hydrogen being the other product. Two types of cells are in use. The first and by far the most important employs a diaphragm to separate the anode and cathode compartments. A second type of cell utilizes a mercury cathode with which the sodium forms an amalgam. 

The anolyte is evaporated to increase the chloride concentration from 75-250 gdm and cobalt, and most of the iron, is then extracted by the organic solvent. The nickel containing raffinate is diluted by condensate from the evaporation and returned to the Ni-cathode compartments in the diaphragm electrolytic cells for precipitation of nickel. Stripping of cobalt from the organic solvent is performed with the weakly acidic condensate. The strip liquor is fed to the Co-cathode compartment in the electrolytic cells. 

Other types of electrolytic cells, although not so commonly used today, are also known. In a diaphragm type cell that separates the cell into anode and cathode compartments, an aqueous solution of potassium chloride is electrolyzed. Potassium hydroxide and hydrogen are produced at the cathode and chlorine is hberated at the anode. The solution discharged from the cell is... 

In 1808 Reuss de la Soc. de Moscou, ii. 327,1809) observed that on passage of an electric current through a cell containing an earthenware diaphragm the electrolyte was transferred from the anode to the cathode compartment. Porret Fogg. Ann. LXVI. 272,... 

In a diaphragm cell, the anode and cathode compartments are separated by a porous diaphragm (Figs. 11.1 and 11.2). Formerly, diaphragms were made of asbestos, but now special polymers created for chloralkali electrolysis have been introduced. 

Electrolysis of the resulting solution in a diaphragm cell with carbon or platinum cathodes resulted in liberation of arsenic in the cathode compartment. Extraction of the ores with sulphydroxides of the alkaline earth metals and subsequent electrolysis has also been suggested.4 These methods have little application, however, since the arsenic in the common ores, such as arsenopyrite and ieucopyrite, cannot be extracted as sulphide. 

The G-riesheim Elektron Company2 use a closed diaphragm cell for preparing metallic permanganates, which is fitted with tubes for the escape of electrolytic gas. Their method for preparing the calcium salt is as follows The cathode compartment contains caustic potash solution, and the anode compartment is filled with saturated manganate... 

Electrolytic sulphuric acid 3 is produced and a concentration as high as 95 per cent, obtained by oxidising sulphurous acid in a diaphragm cell with a cylindrical nickel cathode and an anode of platinum gauze. A porous cup or cell which acts as cathode is filled with sulphuric acid or sodium sulphite, and the outer anode compartment contains a solution of sulphur dioxide which is kept saturated during the process by passing in the gas COn-... 

Silicic acid,1 in a form which is soluble and chemically pure, can be obtained by employing a divided cell with alkali silicate in the anode compartment. Perforated electrodes are fitted against the diaphragm wall, and during electrolysis alkali diffuses into the cathode compartment whilst silicic acid remains in the anode compartment. Hydrated silica is thus separated in a pure form specially suitable for stabilising colloids. 

In concentrated sulphuric acid solution, Gattermann1 and his co-workers have shown that with platinum cathodes aminohydroxy-bodies result. With diaphragm cells in which the cathode compartment is separated from the anode, they found that all nitro-compounds in which the... 

The diaphragm in the diaphragm cell (Fig. 2) prevents the diffusion of sodium hydroxide toward the anode. The anode solution level is maintained higher than in the cathode compartment to retard hack migration. If sodium hydroxide built up near the anode it would react with chlorine to give sodium hypochlorite as a side product. 

The mercury cell (Fig. 3) has no diaphragm but is made of two separate compartments. In the electrolyzing chamber the dimensionally stable anodes of ruthenium-titanium cause chloride ion oxidation that is identical to that of a diaphragm cell. The cathode is made of a sodium amalgam flowing across the steel bottom of the cell at a slight angle from the horizontal and promotes the reduction of sodium ions to the metal. The sodium... 

Bis[dimethylpropylsilylmethyl] Ditellurium5 An H-shapcd electrolytic cell with a ealholyte volume of 100 ml is fitted with a tellurium cathode (99.99% purity, 15-20 cm2 surface area) and a platinum-net anode. To the cathode compartment, separated from the anode by a ceramic diaphragm of 1.6 gm pore size, are added 100 ml of a 1 molar solution of dry sodium perchlorate in dimethylformamide and the catholyte is deaerated with argon. At a cathode potential of 1.4 V with respect to an aqueous saturated calomel electrode, 2500... 

---