Klóralkalí

Klóralkalí refers to the industrial process used to produce chlorine and sodium hydroxide (caustic soda) from a brine solution, which is essentially sodium chloride (salt) dissolved in water. This electrochemical process involves passing an electric current through the brine, which causes a chemical reaction. There are three main electrolytic methods employed in the klóralkalí industry: the mercury cell process, the diaphragm cell process, and the membrane cell process.

The mercury cell process uses a mercury cathode, where sodium is deposited and then forms an amalgam with the mercury. This amalgam reacts with water to produce sodium hydroxide and hydrogen gas. While it yields high-purity sodium hydroxide, environmental concerns related to mercury emissions have led to its decline.

The diaphragm cell process uses a porous diaphragm to separate the anode and cathode compartments. Chlorine gas is produced at the anode, and sodium hydroxide and hydrogen gas are formed at the cathode. This method is less energy-intensive than the mercury cell but produces a less pure sodium hydroxide solution that requires further purification.

The membrane cell process is the most modern and energy-efficient method. It utilizes an ion-exchange membrane to separate the anode and cathode compartments. This membrane allows sodium ions to pass through but prevents chlorine and hydroxide ions from mixing. The membrane cell process produces high-purity chlorine and sodium hydroxide with significantly lower energy consumption and fewer environmental impacts compared to the older methods. The klóralkalí process is fundamental to the chemical industry, providing essential raw materials for a wide range of products, including plastics, paper, textiles, and detergents.