Inorganic chemistry

What is distillation definition and meaning?



What is distillation definition and meaning?

Distillation definition:

Distillation definition is as a process of separating two substances forming a homogeneous mixture. Each liquid following an evaporation temperature curve at a given pressure (for example 82 ° C for a mixture of 50% water and 50% ethanol), it suffices to heat the mixture and collect the vapor of the one which is the most volatile up (ethanol in our example) as you go. This is then cooled by passing through a coil to give the distillate.

Fractional distillation

When liquids have sufficiently distant boiling temperatures, simple distillation is sufficient. Otherwise, a fractional distillation will have to be carried out.

 The latter is carried out using a distillation column (for example a Vigreux column) comprising different levels of hollow points which condense the vapors as they rise. With a sufficient number of stages, an almost pure distillate of the most volatile liquid is obtained.

separation complete however, is not always possible to get. In the case of the water-ethanol mixture for example, a proportion of 95% ethanol to 5% water is obtained.

Distillation involves heating a liquid to extract a substance in the form of condensed vapor.

History of distillation

The first stills used for distillation were found in Mesopotamia, dating back around 3,500 years. First used to make perfumes and decoctions, they were then used to produce eaux-de-vie by distillation of fermented fruits. Distillation was also widely used by alchemists in the Middle Ages. Stills and retorts have largely been replaced today but are still appreciated for certain fine alcohols and liqueurs such as cognac or scotch whiskey, as well as for essential oils in perfumery.

Uses of distillation

Distillation is a process widely used in industry to separate or purify products.

  • Oil refining : 
  • crude oil is injected into a large distillation tower about 60 meters high where it is heated to 400 ° C. Thelightest hydrocarbons ( gas and petrol) are thus collected at the top of the tower, the heaviest (oils, bitumens, fuel oil, etc.) remaining at the bottom. Medium hydrocarbons undergo a second phase of so-called vacuum distillation, making it easier to recover the heavy residues whose boiling point is lowered.
  • Chemistry:
  • fractionation towers are used to separate or purify gases ( oxygen , liquid nitrogen , argon , helium, etc.). The distillation of chlorosilane also produces high quality silicon for the semiconductor industry .
  • Desalination of sea water.
  • Perfumery and pharmacy: distillation is used to extract aromatic compounds from plants, or to obtain water of high chemical and microbial purity for the manufacture of medicines.
  • Food:
  • distillation is mainly used for the production of spirits, but conversely is also used to eliminate alcohol to obtain alcohol-free beer, for example.

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