Electrolysis, of brine

Manufacture is either by reaction of molten sodium with methyl alcohol or by the reaction of methyl alcohol with sodium amalgam obtained from the electrolysis of brine in a Castner mercury cell (78). Both these methods produce a solution of sodium methylate in methanol and the product is offered in two forms a 30% solution in methanol, and a soHd, which is a dry, free-flowing white powder obtained by evaporating the methanol. The direct production of dry sodium methylate has been carried out by the introduction of methanol vapors to molten sodium in a heavy duty agitating reactor. The sohd is supphed in polyethylene bags contained in airtight dmms filled in a nitrogen atmosphere. 

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). 

Production and uses of LiOH have already been discussed (p. 70). Huge tonnages of NaOH and KOH are produced by electrolysis of brine (pp. 71, 73) and the enormous industrial importance of these chemicals has already been alluded to. 

Recently it has been shown that the oxides of the platinum metals can have a higher corrosion resistance than the metals themselves , and have sufficient conductivity to be used as coatings for anodes, e.g. with titanium cores. Anodes with a coating of ruthenium dioxide are being developed for use in mercury cells for the electrolysis of brine to produce chlorine , since they are resistant to attack if in contact with the sodium-mercury amalgam. 

Hypohalite ions, XO, are formed when a halogen is added to the aqueous solution of a base. Sodium hypochlorite, NaClO, is produced from the electrolysis of brine when the electrolyte is rapidly stirred, and the chlorine gas produced at the... 

Thanks to its high stability and permselectivity, Nation has been used as a Na+ conductor in membrane electrolysis of brine in the chlor-alkali industry. This application was introduced in the early 1980s and is by far the most important use of ionomer membranes. 

Chlorine gas, produced by electrolysis of brine, was dried by passage through a mist of sulfuric acid in a drying tower, where static charge was generated. An explosion in the tower, (presumably involving hydrogen as fuel) was attributed to initiation by static spark. 

ELECTRICAL ENERGY Elevated voltage Electrical shock from process using electricity, such as electrolysis of brine... 

Electrolysis of brine to produce chlorine and caustic soda by-product . 

Table 6.1 summarizes the uses of salt. Nearly half is consumed in the important electrolysis of brine to form two top 50 chemicals, sodium hydroxide and chlorine. One fourth is used on highways for deicing and competes with calcium chloride in this application. The food industry and animal feeds make up other important uses. Salt is surpassed only by phosphate rock in total production of all minerals. Its annual production is nearly 90 billion lb. 

In 1892 the electrolysis of brine was discovered as a method for making both sodium hydroxide and chlorine. This rapidly grew in importance and since the 1960s it has been the only method of manufacture. Among electrolytic industries it is the second largest consumer of electricity, aluminum manufacture being the largest. 

In contrast to this direct chlorination there is the oxychlorination of ethylene using hydrogen chloride and oxygen, the other major method now used. Since the chlorine supply is sometimes short and it is difficult to balance the caustic soda and chlorine demand (both are made by the electrolysis of brine), hydrogen chloride provides a cheap alternate source for the chlorine atom. Most of the ethylene dichloride manufactured is converted into vinyl chloride by eliminating a mole of HCl, which can then be recycled and used to make more EDC by oxychlorination. EDC and vinyl chloride plants usually are physically linked. Most plants are 50 50 direct chlorinationroxychlorination to balance the output of HCl. 

Chlorine is produced industrially by electrolysis of brine using either mercury cathode cells or, preferably, various commercially available membrane cells. Chlorine gas is hberated at the anode while sodium hydroxide and hydrogen are liberated at the cathode ... 

Chlorine (Cl ) and sodium hydroxide (NaOH) are two important chemicals produced by electrolysis. Chlorine and sodium hydroxide are generally among the top ten chemicals produced annually in the United States. The electrolysis of brine or aqueous NaCl solution is used to produce chlorine, sodium hydroxide, and hydrogen (Figure 14.14). The chloride ion in the brine solution is oxidized at the anode, while water is converted at the cathode according to the following reactions ... 

Chlorine gas is produced by the electrolysis of brine (sodium chloride) in Castner-Kellner cells (first operated in 1886), the main purpose of which is the production of sodium hydroxide solution. Williams (1972, p98) reports that the extent to which the Castner-Kellner process was worked in Britain depended on the ability to dispose of the chlorine. In this light the production of chlorinated organic compounds can be seen as a response to the need to use chlorine. The argument that we need to produce chlorinated organic compounds to use up chlorine was indeed put to me by manufacturers of polyvinyl chloride (PVC) at a DETR-organized seminar on the lifecycle assessment of PVC in July 2001 PVC is the only product made in sufficient quantities to use up all the chlorine produced by other processes. This suggests that if a particular use of a chemical is stopped, because there is a better (less hazardous) way of achieving that purpose, it will have knock-on effects on the availability of chemicals that are co-produced... 

A major source of chlorine gas, Cl2, is from the electrolysis of brine, which is concentrated saltwater, NaCl(aq). What other two products result from this electrolysis reaction Write the balanced chemical equation. 

The electrolysis of brine (saltwater) yields chlorine gas, Cl2, in addition to sodium hydroxide, NaOH, and hydrogen gas, H2. 

In applications such as the electroreduction of Figure 15.21(c) and electrolysis of brine to caustic and chlorine, single membranes serve as diaphragms between electrodes, permitting passage of ions but retarding diffusion and mixing of feed and product solutions. 

Figure 19.17. Overvoltage and distribution of voltage drops in cells (Jtiine, 1985). (a) Overvoltage of hydrogen on some metals, (b) Voltage distribution in two kinds of cells for electrolysis of brine, (c) Variation of voltage distribution with current density in the electrolysis of HC1. (d) Schematic of voltage profile in a bipolar cell with five pairs of electrodes.

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