Klóralkália

Klóralkália refers to the industrial process of electrolytically producing chlorine gas and alkali metal hydroxides from a salt solution. The most common application is the chlor-alkali process, which uses brine (a concentrated aqueous solution of sodium chloride) as the starting material. Through electrolysis, sodium chloride is split into sodium hydroxide (caustic soda), chlorine gas, and hydrogen gas. This fundamental chemical process is vital for numerous industries.

There are three primary methods for carrying out the chlor-alkali process: the mercury cell process, the diaphragm cell process, and the membrane cell process. The mercury cell process uses a flowing mercury cathode, which forms an amalgam with the sodium, which is then reacted with water to produce sodium hydroxide. While effective, concerns over mercury pollution have led to its decline. The diaphragm cell process uses a porous diaphragm to separate the anode and cathode compartments, preventing the mixing of chlorine and hydrogen. The membrane cell process, considered the most energy-efficient and environmentally friendly, utilizes a selectively permeable ion-exchange membrane to separate the products.

The products of the chlor-alkali process are indispensable. Chlorine is used in water purification, the production of plastics like PVC, solvents, and pharmaceuticals. Sodium hydroxide is crucial for the manufacturing of paper, textiles, soaps, detergents, and in aluminum production. Hydrogen gas can be used as a fuel or in other chemical syntheses. The chlor-alkali industry is a cornerstone of modern industrial chemistry, underpinning the production of countless everyday materials and essential services.