What is Distillation?

Distillation is a process that has been used by humankind for thousands of years ago. It was believed to be first used by the Arab chemists to separate perfume. Today, distillation plays a significant role in the organic chemistry. Chemists can identify and purify organic compounds using the distillation method.

How is the distillation process done? The process involves heating liquid until it boils thus forcing the components to separate. The idea is that different compounds in a liquid mixture have different boiling points. A certain degree of heat will be used to bring one compound to its boiling point until it is transformed into its gas phase. Boiling point is a certain degree of heat that when reached, will bring a liquid to boil.

The liquid in its gas form will condense back into its original state. The process is repeated until all the compounds in the mixture are separated. The idea of distillation is to split a compound from a non-volatile or less volatile material. Generally, distillation is used to separate liquid mixtures. However, it can also be applied to gases by reversing the process. Liquefying gas is possible through changes in temperature and pressure.

There are many uses of distillation especially on commercial processes. Major industrial products such as gasoline, distilled water, xylene, kerosene, paraffin, alcohol etc. are just some that uses the process of distillation. Distillation has four main groups in terms of its application. The four groups are known as laboratory scale, industrial distillation, perfume and medicinal distillation, and food processing.

There is a distinction between laboratory scale and industrial distillation. The difference is that laboratory scale is performed in batch while industrial distillation is performed constantly. Batch distillation is characterized by a still that is supplied with feed mixture. This process is prepared in batch. Separated component fractions are collected one after the other from most volatile to less volatile. The non-volatile fractions are removed at the end of the process.

Continuous distillation is considered to have better control of the separation process compared to batch distillation. This distillation process involves keeping the source material, vapors, and distillate at a constant composition. This is made possible by meticulously replenishing the source material. The fractions from both vapor and liquid in the system are removed after.

If there are four major groups of distillation, there are also three main types. The three main types of distillation are simple, fractional and destructive.

Simple distillation is done when separating solid impurities from a liquid. The best example of this process is by separating salt and other minerals from water. When you put water to a boiler and reached its boiling point, vapors are produced. A condenser collects the vapor and passes it through a vessel for collection. After all the water evaporates, solid impurities remain at the bottom of the boiler.

Fractional distillation is a method used when two or more liquids need to be separated from a single mixture. In this method, different boiling points are applied for each compound in the mixture that needs separated. Liquids have various boiling points. The process starts from applying the lowest boiling point and increased until the compound with the highest boiling point is separated.

Destructive distillation is otherwise known as dry distillation. This type of distillation is used to decompose a solid substance by heating. The process destroys the original substance and as a result, new substance is formed. One good example of this type of distillation is a wood converted into charcoal.