Electrolytic conversion

A newer approach developed for producing commercial quantities of high purity AP (8,36) involves the electrolytic conversion of chloric acid [7790-93 ] to perchloric acid, which is neutralized by using ammonia gas ... 

Industrially, chlorine is obtained as a by-product in the electrolytic conversion of salt to sodium hydroxide. Hazardous reactions have occuned between chlorine and a variety of chemicals including acetylene, alcohols, aluminium, ammonia, benzene, carbon disulphide, diethyl ether, diethyl zinc, fluorine, hydrocarbons, hydrogen, ferric chloride, metal hydrides, non-metals such as boron and phosphorus, rubber, and steel. 

In order to obtain a definite breakthrough of current across an electrode, a potential in excess of its equilibrium potential must be applied any such excess potential is called an overpotential. If it concerns an ideal polarizable electrode, i.e., an electrode whose surface acts as an ideal catalyst in the electrolytic process, then the overpotential can be considered merely as a diffusion overpotential (nD) and yields (cf., Section 3.1) a real diffusion current. Often, however, the electrode surface is not ideal, which means that the purely chemical reaction concerned has a free enthalpy barrier especially at low current density, where the ion diffusion control of the electrolytic conversion becomes less pronounced, the thermal activation energy (AG°) plays an appreciable role, so that, once the activated complex is reached at the maximum of the enthalpy barrier, only a fraction a (the transfer coefficient) of the electrical energy difference nF(E ml - E ) = nFtjt is used for conversion. 

In amperometric detectors, the eluent flows by the surface of the glassy carbon electrode in which only 5-15% of the electroactive species is present and this undergoes electrolytic conversion (oxidation or reduction) as the surface area of the electrode is relatively small. 

In coulometric detectors, the eluent flows through a porous graphite electrode such that, in theory, 100% of any electroactive species will undergo electrolytic conversion. As a result, this significantly increases the detection sensitivity, as the surface area is relatively large. 

Litcht S (2001) Multiple band gap semiconductor/electrolyte conversion. J Phys Chem B 105 6281... 

Another preparative method involves electrolytic conversion of aqueous sulfuric acid to peroxydisulfate followed by hydrolysis to H2O2 (Weissenstein process). The reaction steps are as follows ... 

At distances greater than 8, concentrations are maintained homogeneous by the stirring action. As long as the electrode area is small (microelectrode) relative to the solution volume and the experiment is not prolonged, the bulk concentrations will not be altered appreciably by the electrolytic conversion of O to R at the surface. 

Acids and bases can be obtained if the electrode reactions are involved for example the electrolytic conversion of ammoniumsulfate in ammo-niumhydroxide and sulfuric acid, using a positive membrane has been patented (129). 

Also is claimed the electrolytic conversion of sodiumchloride in sodiumhydroxide and chlorine (18). In all these instances, the selective membrane is applied in order to increase the current efficiency by either impeding the disappearance of OH- ions from the cathode cell to the anode cell, or that of H+ ions in the reverse direction. 

Cell Cathode Catholyte (Electrolyte) Conversion benzene (%) Selec- tivity (%) Current efficiency (%) Ref. 

Surface polishing can be achieved under certain conditions of electrochemical dissolution, which is a reverse process of electroplating (EP). A simple electrochemical cell is shown in Fig. 10.1. Two metal (e.g., Cu) bars are immersed in an electrolyte. A voltage is applied between the two bars. The one connected to the positive pole of the power supply is anode. The other one is cathode. The positive potential applied to the anode may pump out electrons from copper atoms on the anode surface. As a result, copper dissolution may occur in certain electrolytes. Conversely, copper deposition may occur on the cathode. That is, copper electroplating results when the working electrode is chosen to be cathode, and copper dissolution is accomplished when the working electrode is chosen to be the anode. 

The process used by the former Standard Oil of Ohio (SOHIO currently BP America) involved electrolytic conversion of HCN to cyanogen bromide, and subsequent conversion to cyanamide by ammonolysis, then to melamine by trimerization ... 

One way of producing carbon nanomaterial in the condensed phase is the electrolytic conversion of graphite electrodes in a melt of alkali halogenides. Depending on the reaction conditions, various carbon nanostructures are formed especially in molten hthium chloride and bromide. In the apparatus shown in Figure 4.22, the depth of immersion and the amperage are the leading parameters to control whether MWNT, carbon onions, or amorphous material are the main product. Apart from that, the temperature is another important factor as carbon nanostructures wiU only be formed above 500 °C. The carbon onions observed in... 

One can extend this cycle chemistry by putting electricity to use. In short, it is possible to accomplish electrolytic reduction of nitrogen and to develop the phenomenon into a cycle (Figure 3). Thus, we have achieved true catalytic electrolytic conversion of nitrogen to ammonia, by means of a process based on the behavior of titanium. This system was initiated at Stanford by Akermark (14) and developed by Seeley (J5). 

The major source of PFCs is the aluminum industry, CF4 and C2F6 being released as byproducts during the electrolytic conversion of aluminum oxide to aluminum. Annual CF4 emissions... 

Reductive Dehalogenations Microemulsions are usually more useful than micelles for electrochemical synthetic applications because larger amounts of polar and nonpolar reactants can be solubilized. Electrochemical catalysis has been used in microemulsions for the electrolytic conversion of organohalide pollutants to hydrocarbons [53] using mediators such as metal phthalocyanines and cobalt complexes. Microemulsions were used for the complete electrochemical catalytic... 

For industrial applications of ceric oxidation a regeneration of the oxidant is necessary. Electrolytic conversion of Ce(III) into Ce(IV) is described in some publications or patent literature. Thus, p-xylene was converted into 4-methyl-benzaldehyde by catalytic amounts of ceric sulfate in sulfuric acid with an electrolytic regeneration of Ce(IV) (70). Benzylic oxidation appears to start by the formation of a cation radical which then gives a benzyl radical. 

Scheme 13.4. In the upper part, a representation of the oxidation of tropine to an N-methyl-pyrrolidinedioic acid (tropinic acid) and the subsequent production of piperylenedicarboxylic acid and pimelic acid (heptanedioic acid). In the lower part, a representation of the electrolytic conversion of glutaric acid (pentanedioic acid) to suberic acid (octanedioic acid) and carbon dioxide (CO2) and thence to cycloheptanone and, in two different ways, to cycloheptene.

Aqueous electrolytes are characterized by high ion conductivity and consequently have a very low equivalent series resistance. The major drawback to these electrolytes is their voltage, which is hmited to around 1.2 V. Organic electrolytes have low ion conductivity and therefore a relatively high equivalent series resistance in comparison with aqueous electrolytes. Conversely, their voltage capacitance is relatively high, at aroimd 3 V. Activated-carbon supercapacitors are the most fully developed industrially. 

Anodization The electrolytic conversion of an anodic surface in an electrolysis cell or oxygen plasma (plasma anodization) to an oxide. Example Aluminum anodization. 

Electrolytic conversion The production of a compound layer on the surface of an electrode in an electrolysis cell. Example Anodization. 

Uses Surfactant used in electrolytic conversion coalings, plating bath antimisl, electronic etch baths, alkaline cleaners, and plastic pteplate etchants Properties Free-flowing powd. low. sol. in water and most inorg. solv. surf. tens. 22 dynes/cm (0.1% aq.) pH 7-8 (0.1% aq.) 100% act. 

Uses Surfactant in floor polish emulsions, aq. coatings, photographic processes, electrolytic conversion coatings, fluoropolymer emulsions, specialty inks, electronic etch baths, alkaline cleaners, and leak detector soi ns. leveling agent in alkaline systems foaming agent... 

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