Diaphragm cells anode compartment

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). 

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. 

This type of electrochemical reactor is composed of two bodies by mechanical manufacturing [66, 67]. It contains a two-compartment cell with an anodic and cathodic chamber separated by a membrane as diaphragm. The anodic chamber is equipped with a carbon felt anode made of carbon fibers a platinum wire is inserted in the cathodic chamber (Figure 4.30). 

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. 

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).

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. 

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... 

Fig. 6. Cell for macroscale electrolysis at controlled potential consisting of a 2-liter beaker covered with a glass plate G, containing holes for a silver/silver chloride referenoe electrode R, the anode compartment, a cooling coil S, a thermometer, an inlet for nitrogen, and one for withdrawing of samples. The mercury cathode C has an area of 125 cm2. The diaphragm D consists of two porous clay cylinders separated by agar containing KC1. The anolyte (15% aqueous NaOH) is continuously renewed through T. Anode A is of stainless steel. From Iversen and Lund.55...

In the last twenty-five years a new process has been developed in the chlor-alkali industry that uses a membrane to separate the anode and cathode compartments in brine electrolysis cells. The membrane is superior to the diaphragm used in diaphragm cells because the membrane is impermeable to anions. Only cations can flow through the membrane. Because neither Cl- nor OH- ions can... 

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