Question

Where is decantation used? Give two examples.

Answer 1

Hint: The process is used where there is a difference in the densities of two substances in the mixture that is to be separated. It is commonly used in sedimentation. Clear water is obtained from mud by giving time for solids to separate. The oil-water emulsion can be separated.

Complete step by step solution:
First let’s see what the decantation process is, then we can easily find its uses in our daily life.
So, Decantation is a process used for separating the mixtures of
a.)Immiscible liquids
b.)A liquid and a solid-like suspension etc.

When we have a mixture of oil and water in a beaker we leave it for some time. What we see are the two separate layers that are not mixed with each other. As we know that water is heavier than oil, so it settles down and oil being lighter forms the upper layer. We can separate these two immiscible layers by slowly pouring the oil layer in another beaker. This way we will be left with the only layer of water.
Thus, in this process, a mixture is allowed to stand so that the gravity pulls the heavier part (liquid in case of two liquids and solid in liquid-solid suspension) at the bottom of the container.
There are several processes in which we use the decantation process.

Example 1:- The most common example of decantation is the separation of wastewater. During the filtration and cleaning of water, decantation is carried out. The dirty water being denser differs from clean water which is lighter. Thus, the dirty water settles down and clean water forms the upper layer.

Example 2:- During extraction of petroleum from sea sources
The hydrocarbons are mixed with seawater and they have to be separated. So, decantation plays an important role here. Oil i.e. hydrocarbons are denser than water. Thus, hydrocarbons form the bottom layer and water forms upper-layer. This way they are separated.

Note: Decantation can be used in many other industrial processes like making food sauces, separation of cream from milk, oil refining and manufacture of vinegar. It is based on the principle that heavy particles settle down faster in the medium.