Distillation is a separation process that uses substances turn of vaporization and condensation , using them selectively to cleave a generally homogeneous mixture .
The latter may contain liquids , a solid mixed in a liquid or liquefied gases, since it takes advantage of one of the inherent characteristics of each substance, such as the boiling point.
It is called the boiling point at the temperature at which a liquid changes its state to gaseous ( evaporates ).
In principle, for the distillation to be carried out, the mixture must be boiled to the boiling point of one of the substances , which will be conducted in a gaseous state to a cooled container in which to condense and recover its liquidity.
See also: Examples of Chromatography
There are several possible types of distillation:
- Simple . As described above, it does not guarantee the purity of the distilled substance completely.
- Fractional . It is carried out by means of a fractionation column, which uses different plates in which the evaporation and condensation is successively produced, guaranteeing a greater concentration of the result.
- Vacuum. It uses vacuum pressure to catalyze the distillation process, reducing the boiling point of the substances in half.
- Azeotropic . It is used to break an azeotrope, that is, a mixture of substances that behave as one, sharing a boiling point. It often includes the presence of separating agents and everything is done according to the Raoult Law.
- Steam . Volatile and non-volatile components are separated from a mixture from the direct injection of steam to promote the separation of the mixture.
- Dry . It is based on the heating of solid materials without the aid of liquid solvents, to produce gases that are then condensed in another container.
- Reactive distillation. This is called alternating distillation , adapted to specific cases of mixtures of substances difficult to separate from their boiling points.
- The refining of oil . To separate the various hydrocarbons and petroleum derivatives , a fractional distillation method is carried out that allows each of these derivative compounds to be stored in different layers or compartments, from the cooking of the crude oil. The gases rise and dense substances such as asphalt and paraffin fall separately.
- The catalytic cracking . Vacuum distillations are often made in the oil processing, from vacuum towers to separate the various gases that are released in the cooking stages of the oil. In this way the boiling of the hydrocarbons is accelerated.
- Purification of ethanol . The process of separating ethanol (an alcohol) from the water produced in laboratories requires a process of azeotropic distillation, in which benzene or other components are added to release the mixture and allow separation.
- Processing of coal . In the production of liquid organic fuels, coal or wood is often used in a dry distillation process, in order to condense the gases emitted during combustion and use them in various industrial processes .
- Thermolysis of mineral salts . Another process of dry distillation, consisting of burning mineral salts and obtaining from them, from the emanation and condensation of gases, various mineral substances of high industrial utility.
- The still . This device invented in ancient Arabic to produce perfumes, medicines and alcohol from fermented fruits, uses the principles of distillation by heating substances in its small boiler and cooling the gases produced in a coil cooled in a new container .
- The production of perfumes . Steam distillation is often used in the perfumery industry, by boiling water and certain types of preserved flowers, in order to obtain a flavored gas that, when condensed, can be used as base liquids. in perfumes.
- Obtaining alcoholic beverages . It is possible to distill the ferment of fruits or other natural products, for example, in a still. The ferment is boiled at about 80 ° C, the boiling temperature of the alcohol, and thus the water, which remains in the container, is separated.
- Obtaining distilled water . The extreme purification of water is produced from a distillation process that extracts all the possible solutes it contains. It is often used in laboratories and industries, and the same mechanism is used to purify water for human consumption.
- Obtaining oils . The recipe for obtaining many essential oils is to boil the raw material (vegetable or animal) until the oil evaporates and then condenses it in a cooled end, so that it recovers its liquidity.
- Desalination of sea water . In many places where there is no drinking water, seawater is used for its consumption, after having distilled it to remove the salt, since the latter does not evaporate when the liquid is heated and remains in the original container.
- Obtaining pyridine . Colorless liquid with a very repulsive odor, pyridine is a compound similar to benzene, widely used in the industry of solvents, drugs, dyes and pesticides. It is often obtained from the distillation of the oil obtained, in turn, from the destructive distillation of bones.
- Obtaining sugars . From coconut and other natural substances, certain sugars can be obtained by a distillation that extracts the water by evaporation and allows the sugar crystals to remain.
- Obtaining glycerin . The process to obtain homemade glycerin includes the distillation of soap residues, because this substance comes from the degradation of certain lipids (as in the Krebs cycle).
- Obtaining acetic acid . This derivative of vinegar has numerous applications in the pharmaceutical, photographic and agricultural industry, and in its processes of obtaining the distillation plays an important role, since it is produced in conjunction with other less volatile substances such as formic acid and formaldehyde.