[Explained] Advantages and Disadvantages of Simple Distillation

 Distillation is a process in which a liquid mixture is purified or separated on by the selective evaporation and condensation.

By this process one can obtain the individual components of the liquid mixture.

Distillation is based on the principle that the liquid in the boiling flask and the vapor have different compositions.

Distillation serves the purpose of separating the liquids of a mixture which has different boiling points, separating liquid from non-volatile components of the mixture and to obtain a relatively pure individual component or components of the mixture.

There are three main types of distillations

1. Simple Distillation
2. Fractional Distillation
3. Steam Distillation
4. Vacuum Distillation
5. Molecular Distillation
6. Fractional Distillation under reduced pressure

In this post we shall discuss about the advantages and disadvantages of Simple distillation.

Advantages and Disadvantages of Simple Distillation
Advantages of Simple Distillation		Disadvantages of Simple Distillation
It requires lesser number of items to carry out simple distillation.		It gives poor separation when compared to other distillation techniques.
The process of Simple distillation is fast.		Relatively pure components are required to perform simple distillation.
Simple distillation consumes lesser energy than any other distillation technique.		There is a need to redo the process multiple times to obtain 99% pure component.
There is efficient separation when the difference in boiling points of the components is more than 50 degree Celsius.		Requires a 50 degree Celsius difference in boiling points else the separation is not satisfactory.

Simple distillation is a process in which two liquids that have a difference in boiling points of at least 50 °C can be purified or separated.

Simple distillation is used to separate hydrocarbons, alcohol, fatty acids, amines, esters and it is most widely used in desalination of sea water. 

You can read about the procedure of Simple distillation here.

Advantages of Simple Distillation

Simple distillation as the name suggests has a very simple apparatus when compared to other distillation techniques.

It has lesser number of items that are required to carry out simple distillation.

The items that are required are distillation apparatus which constitutes distilling flask, condenser, receiving flask and adapters. The other items may include, boiling stones, Bunsen burner and burette clamps.

One point to note is that the apparatus for simple distillation is a sealed system. 

The process of simple distillation is fast. 

The products are obtained very quickly. The reason for this is that the liquid mixture on which simple distillation is carried out generally has a very high difference of boiling points.

Simple distillation consumes lesser energy when compared to other distillation techniques. 

Lesser energy consumption is due to the type of mixtures used to perform simple distillation and the type of apparatus used.

Efficient separation if the difference in boiling point of the components is more than 50 °C.

When a mixture of liquids heated to its boiling point the more volatile component of the mixture will higher concentration in the vapor phase, due to it's tendency to escape into the vapor phase.

Therefore when there is a significant difference in the boiling points of the components of the mixture the more volatile component will escape into the vapor phase, which will then be condensed and stored in the receiving flask. 

This will result in the separation of two components of the mixture and one can obtain relatively pure individual components.

Disadvantages of Simple Distillation

Simple distillation has a fair share of disadvantages as well. We shall discuss them in detail below. If the following criteria is not fulfilled simple distillation should not be performed.

Having a significant difference of about 50 ℃ in boiling point is also a con. 

As mixtures whose components do not have a huge difference in boiling points can be efficiently separated.

An example for this can be a mixture of cyclohexane and toluene which has both in equal amounts.

The difference in their boiling points is 29.85 C. Because it is less than 50 C, to obtain pure components the process of simple distillation must be carried out multiple times. 

Simple distillation gives poorer separation of components when compared to other distillation techniques.

Let us take fractional distillation for instance as it the most used and studied type of distillation and also because the apparatus used in fractional distillation is also very similar to the apparatus used in simple distillation.

The only major difference between the apparatus of simple and fractional distillation is that the setup of fractional distillation has a fractionating column attached to the top distillation flask and beneath the condenser.

This fractionating column provides a larger surface area on which rising vapors condense and later they re-vaporize. It also helps to supply temperature gradient over which the distillation can occur. 

And thus the purer components are obtained when compared to simple distillation.

Relatively pure liquids are required to perform simple distillation.

The process of simple distillation requires a mixture of liquids that does not contain many impurities. If there are impurities present in the mixture, then their boiling points might be different that of the pure component. It may even alter the boiling point of the component as a whole.

Need to redo the process to obtain a 99% pure component.

When performing a simple distillation of the mixture consisting of cyclohexane and toluene in equal amounts, the process needs to be redone multiple times to obtain a 99% cyclohexane.

At the end of the first simple distillation, 80% cyclohexane and 20% toluene is obtained. When this is distilled again a 95% cyclohexane and 5% toluene mixture is obtained. This is pure but still not pure as desired.

Therefore if the 95% cyclohexane and 5% toluene mixture is distilled again then the resultant distillate would be of 99% cyclohexane.

Thus for the cyclohexane-toluene mixture three vaporization-condensation cycles are required. Each vaporization-condensation cycle is known as simple distillation.

You may also want to read:

Uses of Simple Distillation

10 Advantages and Disadvantages of Fractional Distillation