Anode compartments

At the cathode, water molecules are discharged yielding gas and hydroxide ions, OH. Some of the caustic generated in the cathode compartment back-migrates to the anode compartment and reacts with dissolved chlorine (Cl2, ) to form chlorate as follows... 

Current is fed into the electrolyzer by means of anodic and cathodic end elements. The anodic compartment of each cell is joined to an independent brine feed tank by means of flanged connections. Chlorine gas leaves each cell from the top, passing through the brine feed tank and then to the cell room collection system. Hydrogen leaves from the top of the cathodic compartment of each cell the cell Hquor leaves the cathodic compartment from the bottom through an adjustable level connection. 

The generated chlorine dioxide must be air stripped from the anode compartment in order to achieve high chlorite conversion efficiency. Sodium ions from the anode compartment are transported into the cathode compartment, forming sodium hydroxide [1310-73-2] and hydrogen gas coproducts ... 

A.sahi Chemical EHD Processes. In the late 1960s, Asahi Chemical Industries in Japan developed an alternative electrolyte system for the electroreductive coupling of acrylonitrile. The catholyte in the Asahi divided cell process consisted of an emulsion of acrylonitrile and electrolysis products in a 10% aqueous solution of tetraethyl ammonium sulfate. The concentration of acrylonitrile in the aqueous phase for the original Monsanto process was 15—20 wt %, but the Asahi process uses only about 2 wt %. Asahi claims simpler separation and purification of the adiponitrile from the catholyte. A cation-exchange membrane is employed with dilute sulfuric acid in the anode compartment. The cathode is lead containing 6% antimony, and the anode is the same alloy but also contains 0.7% silver (45). The current efficiency is of 88—89%, with an adiponitrile selectivity of 91%. This process, started by Asahi in 1971, at Nobeoka City, Japan, is also operated by the RhcJ)ne Poulenc subsidiary, Rhodia, in Bra2il under Hcense from Asahi. 

Brewis et al. used TOF-SIMS to determine the surface composition of hydrocarbon polymers after electrochemical pretreatment with nitric acid alone or in the presence of silver ions [58J. AgNO was generated by electrolysis of a 0.1 M solution of silver nitrate in 3.25 M nitric acid in the anode compartment of a... 

A solution of the ketone (10 mg) in dry dioxane (5 ml) is placed in the cathode compartment of the cell. Then 10% deuteriosulfuric acid in deuterium oxide (5 ml) is added slowly with stirring. A small additional quantity of dioxane may be necessary to maintain a homogeneous solution. The anode compartment is filled with an identical solvent mixture and the electrode inserted. The current is adjusted to 1(X) milliamps and the electrolysis is continued for 6-10 hr with rapid stirring. The progress of the reaction is... 

The anode compartment contains a reference electrode and counterelectrode and by means of a potentiostat the anode side is maintained at a constant potential. The coverage of adsorbed hydrogen on the cathode side will depend on the current density i and the nature of the electrolyte solution, and the cell can be used to study the effect of a variety of factors (composition and structure of alloys, pH of solution, effect of promoters and inhibitors) on hydrogen permeation. 

This reaction, like that between Zn and Cu2+, can serve as a source of electrical energy in a voltaic cell The cell is similar to that shown in Figure 18.2 except that, in the anode compartment, a nickel electrode is surrounded by a solution of a nickel(II) salt, such as NiCl2 or NiS04. The cell notation is Ni Ni2+ Cu2+ Cu. 

A fuel cell is an electrochemical reactor with an anodic compartment for the fuel oxidation giving a proton and a cathodic compartment for the reaction of the proton with oxygen. Two scientific problems must be solved finding a low-cost efficient catalyst and finding a membrane for the separation of anodic and cathodic compartments. The membrane is a poly electrolyte allowing the transfer of hydrated proton but being barrier for the gases. 

This reaction is of great technological interest in the area of solid oxide fuel cells (SOFC) since it is catalyzed by the Ni surface of the Ni-stabilized Zr02 cermet used as the anode material in power-producing SOFC units.60,61 The ability of SOFC units to reform methane "internally", i.e. in the anode compartment, permits the direct use of methane or natural gas as the fuel, without a separate external reformer, and thus constitutes a significant advantage of SOFC in relation to low temperature fuel cells. 

In the membrane-cell process, highly selective ion-exchange membranes of Du Font s Nation type are used which allow only the sodium ions to pass. Thus, in the anode compartment an alkali solution of high purity is produced. The introduction of Nafion-type membranes in chlor-alkali electrolyzers led to a significant improvement in their efficiency. Today, most new chlor-alkafi installations use the membrane technology. Unfortunately, the cost of Nafion-type membranes is still very high. 

This type of electrolytic cell consists of anodes and cathodes that are separated by a water impermeable ion-conducting membrane. Brine is fed through the anode where chlorine gas is generated and sodium hydroxide solution collects at the cathode. Chloride ions are prevented from migrating from the anode compartment to the cathode compartment by the membrane and this, consequently, leads to the production of sodium hydroxide, free of contaminants like salts. The condition of the membrane during operation requires more care. They must remain stable while being exposed to chlorine and strong caustic solution on either side they must allow, also, the transport of sodium ions and not chloride ions. 

The hulk solution may become depleted. In free-convection experiments, the cathode and anode compartments are often separated by a diaphragm to prevent interaction of the convection patterns. Under these conditions, replenishment of the catholyte does not take place. Examples of sagging limiting-current plateaus caused by bulk depletion can be found in... 

Berka et al [59] described an accurate and reproducible coulometric method, with chlorine electrogenerated at the anode, for the determination of micro quantities of primaquine phosphate. Titration was carried out in an anode compartment with a supporting electrolyte of 0.5 M sulfuric acid-0.2 M sodium chloride and methyl orange as indicator. One coulomb was equivalent to 1.18 mg of primaquine phosphate. The coefficients of variation for 0.02-0.5 mg of primaquine phosphate were 1-5%. Excipients did not interfere. 

A In this concentration cell E°ax = 0.000 V because the same reaction occurs at anode and cathode, only the concentrations of the ions differ. [Ag+ ] = 0.100 M in the cathode compartment. The anode compartment contains a saturated solution of AgCl(aq). 

QB For this cell because the electrodes are identical, the standard electrode potentials are numerically equal and subtracting one from the other leads to the value c°dl = 0.000 V. However, because the ion concentrations differ, there is a potential difference between the two half cells (non-zero nonstandard voltage for the cell). [Pb2+] = 0.100 M in the cathode compartment. The anode compartment contains a saturated solution of Pbl2. We use the Nemst equation (with n = 2) to determine [Pb2+] in the saturated solution. 

In the anode compartment the oxidation of Mn(II) to Mn(III) takes place which can be used for the synthesis of dioxoviolanthrone (10), which is reduced with NaHS03 to dihydroxyviolanthrone (11), an intermediate for vat dyes [40,62],... 

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