Electrolysis applications

Table 12.37 Redox recipes used in indirect electrolysis application of indigo to cotton yarn [241]...

In 1998, Krupp Uhde became the sole owner of Single Element Technology and continues to put great effort into the further development of membrane cell technology for different electrolysis applications. With a new patent [4] for improved Single Element Technology, Krupp Uhde is ready for the future. 

Drogui, P., Elmaleh, S., Rumeau, M., Bernard, C. and Rambaud, A. (2001) Hydrogen peroxide production by water electrolysis Application to disinfection. J. Appl. Electrochem. 31, 877-882. 

Besides the aforementioned Kolbe dimers, alcohols, esters or ethers can become the major products in the electrolysis of carboxylic acids. These results have suggested that in anodic decarboxylation the intermediate radicals were further oxidized to carbocations that yielded solvolysis and elimination prod-ucts. °2 This part of the anodic decarboxylation, which leads to carbenium ions, is frequently called nonKolbe electrolysis. Applications of the nonKolbe electrolysis to synthesis and to mechanistic investigation of carbocations are summarized in refs. 8,19,20 and 23. ... 

Laguna-Bercero, M.A., Bayliss, R.D., and Skinner, S.J. (2014) LaNb0.84W0.i6O4.08 as a novel electrolyte for high temperature fuel cell and solid oxide electrolysis applications. Solid State Ionics, 262, 298-302. 

PPS fiber has excellent chemical resistance. Only strong oxidising agents cause degradation. As expected from inherent resia properties, PPS fiber is flame-resistant and has an autoignition temperature of 590°C as determined ia tests at the Textile Research Institute. PPS fiber is an excellent electrical iasulator it finds application ia hostile environments such as filter bags for filtration of flue gas from coal-fired furnaces, filter media for gas and liquid filtration, electrolysis membranes, protective clothing, and composites. 

Anode Applications. Graphite has been used as the primary material for electrolysis of brine (aqueous) and fused-salt electrolytes, both as anode and cathode. Technological advances, however, have resulted in a dimensionally stable anode (DSA) consisting of precious metal oxides deposited on a titanium substrate that has replaced graphite as the primary anode (38—41) (see Alkali and chlorine products). 

Pure aluminum is used in the electrolysis protection process, which does not passivate in the presence of chloride and sulfate ions. In water very low in salt with a conductivity of x < 40 yUS cm" the polarization can increase greatly, so that the necessary protection current density can no longer be reached. Further limits to its application exist at pH values < 6.0 and >8.5 because there the solubility of Al(OH)3 becomes too high and its film-forming action is lost [19]. The aluminum anodes are designed for a life of 2 to 3 years. After that they must be renewed. The protection currents are indicated by means of an ammeter and/or a current-operated light diode. In addition to the normal monitoring by service personnel, a qualified firm should inspect the rectifier equipment annually. 

Other industrial applications of electrolysis include extraction/purification of metals from ores, electroplating, and the manufacture of certain chemicals such as sodium hydroxide. In the latter, sodium chloride solution when electrolysed is converted to sodium hydroxide to produce chlorine at the anode and hydrogen at the cathode. Both of these gaseous by-products are collected for industrial use chlorine is used in the production of bleach and PVC hydrogen is used as a fuel, to saturate fats, and to make ammonia. 

The development of electrical power made possible the electrochemical industry. Electrolysis of sodium chloride produces chlorine and either sodium hydroxide (from NaCl in solution) or metallic sodium (from NaCl fused). Sodium hydroxide has applications similar to sodium carbonate. The ad vantage of the electrolytic process is the production of chlorine which has many uses such as production of polyvinyl chloride. PVC, for plumbing, is produced in the largest quantity of any plastic. 

CNTs have been prepared recently by electrolysis and by electron irradiation of tube precursors. For example. Hsu e/ al. [30,31] have described the condensed-phase preparation of MWCNTs by an electrolytic method using a graphite rod (cathode) and carbon crucible (anode) (Fig. 6) in conjunction with molten LiCl as the electrolyte, maintained at 600°C under an Ar atmosphere. Application of a dc current (3-20 A, <20 V) for 2 min yielded MWCNTs (2-10 nm in diameter, >0.5 pm in length) consisting of 5-20 concentric layers with an interlayer... 

The metal is obtained by electrolysis of a fused mixture of 55% LiCl, 45% KCI at 450°C, the first commercial production being by Metallge-selleschaft AG, in Germany, 1923. Current world production of Li metal is about 1000 tonnes pa. Far greater tonnages of Li compounds are, of course, produced and their major commercial applications have already been noted (p. 70). 

Stray-current electrolysis occurring as a result of the application of cathodic protection to a nearby immersed or buried structure is known as cathodic-protection interaction and is described in Section 10.6. 

A similar electrolyte, containing potassium heptafluoroniobate, K2NbF7, can be used for the electrolytic reduction of niobium [37, 542 - 544]. No industrial application, however, was found for the electrolysis of niobium in fluoride-chloride melts. 

Another application of the electrolysis of tantalum and niobium in fluoride melts is in the preparation of intermetalic compounds as a result of the interaction between the electrochemically precipitating metal and the cathode material. Based on an investigation of the electrochemical reduction of K2TaF7 or K2NbF7 in a LiF - NaF melt on nickel cathodes, Taxil and Qiao [565] determined the appropriate conditions for the formation of TaNi3 or NbNi3 in the form of stable phases in the bulk of the obtained layer. 

---