At the turn of the 18th and 19th centuries, several discoveries were made that became the impetus for the birth of a new science - electrochemistry. And the founders of this science were two scientists. This is the Italian physiologist L. Galvani and the English physicist A. Volt, who in 1799 created the first source of chemical current - the Volta Pillar. It was these scientists who managed to find out that when an electric current passes through an aqueous solution of a salt, then chemical transformations occur in this solution, which are now called electrolytic. Electrolysis per se is a rather complex set of different processes. This migration (negative ions tend to the anode, and positive to the cathode) and diffusion of ions. These are also various electrochemical and chemical reactions that occur between the electrolysis products themselves, between these products and the electrolyte, between them and the electrodes.
And the study of these processes is not only of scientific value. The practical use of electrolysis is now very important. For example, pure hydrogen, sodium or nickel can only be obtained in this way. And in industry, electrolytic processes are used for a wide variety of purposes. With their help, inorganic substances such as oxygen, hydrogen, alkalis, chlorine and other non-metals are obtained. Also, electrolysis is used to purify some metals (silver, copper). More electrolytic processes have become the basis for the production of lithium, potassium, sodium, zinc, magnesium and other metals, as well as metal alloys.
In addition, the use of electrolysis in technology is also the production of organic substances, galvanic coatings and the treatment of metal surfaces (electro polishing, boronation, cleaning and nitriding). There are also electrophoresis, electrodialysis, electroforming and other similar processes that have practical applications. Also, the value of electrolysis lies in the fact that with its help pure, almost one hundred percent metals are obtained.
Take at least copper. Copper ore contains its oxides, sulfur compounds, as well as impurities of other metals. And the copper obtained from this ore, with all these impurities, is cast in the form of plates. Then these plates are placed as an anode in a solution of copper sulfate (CuSO4). And then follows the use of electrolysis. A certain voltage is applied to the bath electrodes and pure metal is released at the cathode. And all foreign impurities precipitate or pass into the electrolyte, not standing out on the cathode.
The use of electrolysis is also relevant for the production of aluminum. An aqueous solution is not used in this process, it is replaced by molten bauxite. Such ores contain aluminum oxide, as well as iron and silicon oxide. After treatment of bauxite with alkali, a product called alumina is obtained. This alumina is loaded into a refractory furnace, on the bottom and walls of which coal plates are laid. These plates are connected to the negative of the power source. And the carbon anode, which passes through the wall of this furnace, is connected to the plus. And when the anode is lowered into the furnace, an electric arc arises that melts the alumina. Then, an electrolytic process takes place already in this molten mass. And at the bottom of the furnace, pure (up to 99.5%) aluminum accumulates, which is then poured into molds.
But the use of electrolysis is not only electrometallurgy. In this way, one metal can be coated with a layer of another metal. This process is called galvanostegia and is used to protect the metal surface from oxidation, to give it greater strength, and also to give this surface a better appearance. And as coatings, nickel and chromium are usually used, which are little susceptible to oxidation or noble metals such as silver and gold.
In this case, the product to be electroplated is thoroughly degreased, cleaned and polished. Then it is placed as a cathode in a galvanic bath. The electrolyte in this bath is a solution of a metal salt, which will cover the product. And the anode is made of the same metal. And to make this coating uniform, the cathode is placed between two anodes. Then, a current of a certain power is supplied to the electrodes, and the cathode is coated with a layer of silver, gold, nickel or chromium.
There is also such an application of electrolysis, which is called electroforming. This method produces copies from various metal objects (medals, coins, bas-reliefs). To do this, a copy of the item is made from a plastic material such as wax. Then it is covered with graphite dust to give it electrical conductivity and this copy is placed in the bath, where it serves as a cathode. And by electrolysis, this copy is covered with a layer of metal of the desired thickness. And the wax is then removed by heating. And this is only a small part of the possibilities that a method called electrolysis provides.