In the 18-19th century, several discoveries were made that served the birth of a new science - electrochemistry. Its founders were two scientists: the physiologist from Italy L. Galvani and the English physicist A. Volt. They found that when an electric current passes through an aqueous solution of some salt, chemical processes take place in this solution. They were called electrolytic.
What is electrolysis?
Electrolysis is a rather complex set of certain processes. In other words, it can be said that electrolysis is the migration and diffusion of ions. Also, electrolysis includes various electrochemical and chemical reactions that occur between the products of electrolysis, between these products and the electrolyte, between them and the electrodes.
The study of these processes is important not only for science. The use of electrolysis in practice has become very relevant. For example, pure hydrogen, sodium and nickel are obtained in this way. Electrolytic processes are used for various purposes in industry. In this way, inorganic substances such as oxygen, hydrogen, alkali, chlorine and other non-metals can be obtained.
Electrolysis is also used to purify metals such as gold and silver. Electrolytic processes underlie the production of lithium, potassium, sodium, zinc, magnesium and other metals, as well as metal alloys.
The use of electrolysis in technology
The use of electrolysis in technology consists in the production of organic substances, galvanic coatings and in the treatment of metal surfaces (electropolishing, boriding, cleaning and nitriding). There are also electrophoresis, electrodialysis, electroforming and other similar processes that are actively used in practice.
With the help of electrolysis, one hundred percent pure metals can be obtained. For example, copper. Copper ore contains oxides, sulfur compounds and impurities of other metals. The copper obtained from this ore, with all the impurities, is cast in the form of plates. Then the plates are placed in a copper sulfate solution (CuSO4) as an anode. And only then electrolysis is used. A certain voltage is applied to the bath electrodes - and pure metal is released at the cathode. All the remaining impurities precipitate or pass into the electrolyte without being released at the cathode.
Aluminum is produced in the same way using electrolysis. No aqueous solution is used here. Instead, molten bauxite is used. They contain aluminum oxide, as well as iron and silicon oxide. After bauxite is treated with alkali, a product is obtained, which is called alumina. Alumina is immersed in a refractory furnace, on the bottom and walls of which carbon plates are laid. These plates are connected to the minus of the power supply. A carbon anode passing through the wall of this furnace is connected to the plus. When the anode is lowered into the furnace, an electric arc is formed that melts the alumina. Then, in this molten mass, an electrolytic process takes place - and pure (up to 99.5%) aluminum accumulates at the bottom of the furnace, which is then poured into molds.