Distillation:

It is a process in which a liquid or vapour mixture of two or more substances is separated into its component fractions of desired purity, by the application and removal of heat.

Principle:

Distillation is based on the fact that the vapour of a boiling mixture will be richer in the components that have lower boiling points.

Therefore, when this vapour is cooled and condensed, the condensate will contain more volatile components. At the same time, the original mixture will contain more of the less volatile material.

Method:

Distillation columns are designed to achieve this separation efficiently. Distillation column is a tall metal cylinder internally fitted with perforated horizontal plates used to promote separation of miscible liquids ascending in the cylinder as vapor.

Application: 

• It is used to separate crude oil into more fractions. Gasoline, kerosene and naphtha are fractions separated from crude oil
• Water is distilled to remove impurities, such as salt from seawater.
• Air is distilled to separate its components notably oxygen, nitrogen, and argon for industrial use.
• Distillation of fermented solutions has been used since ancient times to produce distilled beverages with a higher alcohol content.
• Distillation of herbs for perfumery and medicinals (herbal distillate), and food processing.

Types of distillation: 

• Simple distillation.

Simple distillation is designed to evaporate a volatile liquid from a solution of non-volatile substances; the vapour is then condensed in the water condenser and collected in the receiver.

The apparatus consists of a round-bottomed distilling flask bearing a stillhead connected to a water condenser (Liebig condenser). This is attached via a vented delivery bend to the receiver, also a round-bottomed flask. The stillhead has a thermometer adapter with a thermometer.

• Fractional distillation.

Fractional distillation is a manufacturing process that separates the different components in a chemical mixture according to their different boiling points. The liquid is raised to boiling and vapors pass through a tubular column. Components (fractions) with a higher boiling point condense on the column and return to the solution. Fractions with a lower boiling point pass through the column and are collected. using fractional distillation.

• Destructive distillation.

A process by which organic substances such as wood, coal, and oil shale are decomposed by heat in the absence of air and distilled to produce useful products such as coke, charcoal, oils, and gases.