What is Decantation: Definitions, Examples, Procedure, Applications, Advantages, Disadvantages, Filtration

Decantation Overview

Decantation is the process of separating two immiscible liquids with different densities or eliminating insoluble solid particles from a liquid. Decantation is the manual separation of liquid from sediments or another immiscible liquid with a variable density. For example, we've all seen how, if we leave a bucket full of water mixed with sand or mud undisturbed for a short period of time, most of the insoluble particles fall to the bottom due to gravity. If we tilt the bucket and throw the water out, the settled precipitate will remain at the bottom while the relatively clean water may be drained out.

What is Decantation?

Decantation is a method of separating mixtures of immiscible liquids or mixes of a liquid and a solid, such as a suspension. The layer closest to the top of the container is drained out, leaving the other component or the denser liquid of the combination behind. During the separation of two immiscible liquids, a partial separation is seen. To put it simply, decantation is the process of separating immiscible components by moving the top layer to a different container. The technique does not yield a precise or pure result.

Decantation Examples

The following are some the examples of decantation-

1. Milk and Cheese/Cream: Decantation is the process of separating milk and cheese. The cream floats to the top of the liquid and is easily removed by skimming.

   

2. Plasma and Blood: Plasma and blood are separated from the blood by centrifugal decantation.

   

3. Precipitate is Separated From Supernate: Precipitate is separated from supernate using decantation, a chemical process that yields a solid final product. In chemistry, a supernate is a liquid found above a precipitate or sediment. The liquid is frequently clear. The word is particularly applicable to the liquid above a precipitation process. Filtration is recommended over decantation for removing minute particles from liquid.

   

4. Water and Dirt: One method for cleaning murky water is decantation. Because soil and other particles fall to the bottom, clear water is drained. Because certain particles (including microorganisms) are too light to settle with dirt, decanting water does not completely cleanse it. Following decantation, other techniques, such as filtering or distillation, are required to produce drinking water.

   

5. Water and Oil: Water floats on oil. After allowing an oil and water combination to settle for a while, the oil may be drained from it. A separatory funnel can be used to separate the water and oil.

   

Read more about the Difference Between Fats and Oils.

Variations in Decantation

Decantation alone may not be enough for some mixes. This is why we address variants that might enhance the procedure further down. The following are some of the processes of decantation-

Separating Funnel

In decantation, a separating funnel can enhance separation efficiency. This works for immiscible liquid mixes. It consists of a tiny glass container with a flow control stopcock. We let the mixture's components settle as previously. We can let the bottom-most layer flow away while the other layers remain stationary. The stopcock should be used with care to achieve the best results.

Centrifugation

This is frequently applied to solid-liquid combinations. A centrifuge is employed in the procedure to aggressively settle down the mixture's solid component. This results in the formation of a precipitate. The centrifuge's spinning considerably accelerates the settling process. It can also improve separation quality since the solid forms a firm pellet that does not mix back into the liquid.

Loading

Decantation does not always completely separate solid-liquid combinations. If the precipitation is sluggish, we can use centrifugation. Loading is another method for accelerating the separation of mud and water. Alum, a mineral, is added to the mixture during the procedure. This clings to the mud particles, making them heavier and hence settling down faster. This is a component in water filtration systems. 

Read more about the Difference Between Solid, Liquid, and Gas.

Decantation Procedure To Separate Solid And Liquid

Separation processes may be classified into two types-

Separation of Solid-Liquid

The solid is initially allowed to settle at the bottom by gravity in this technique. The liquid is then put into another vessel. If the natural settling process is too sluggish, a centrifuge is used. As additional force is applied to the solid impurities, the centrifuge can accelerate their separation. Loading is employed in this operation. During loading, suspended pollutants are made heavier by adding alum. Impurities settle down faster after getting heavier, making the liquid clear.

Immiscible Liquid Separation

This process is straightforward since it separates two immiscible liquids with differing densities. When two immiscible liquids are combined, two layers develop. The lighter liquid floats on top of the heavier one. As a result, both are separated by dumping the top layer (lighter liquid) into a separate vessel. This process necessitates precision since it is extremely difficult to pour out the entire top layer without also spilling the bottom layer. Using this method, oil and water are separated.

Applications of Decantation

The decantation method helps our daily lives in a variety of ways. Here are a few uses of decantation-

1. Decantation is also used in nanotechnology.
2. Decanted milk with cream on top allows for the separation of milk and cream. This is used in the cheese business.
3. It is used in the froth flotation process. Hydrophobic and hydrophilic materials are separated using a method known as froth flotation.
4. It permits the removal of lipids from raw materials during grape vinegar manufacture.
5. It is used to remove insoluble particle deposits from liquids.
6. It is used to remove plasma from the blood during diagnostic tests.
7. It's used in the sugar industry to turn sugarcane particles into sugar.
8. Mercury is occasionally disposed of in bodies of water, resulting in dangerous water that should not be consumed. This mercury is removed by the decantation method.
9. Red wine is decanted from its sediments, which are mostly crystals of potassium bitartrate, to prevent flavor loss.

Advantages of Decantation

The following are some of the advantages of Decantation-

1. Decantation is a simple procedure. It might be done manually. As a result, it may efficiently separate insoluble sediments or immiscible liquids.
2. It allows you to effectively separate two immiscible liquids. Furthermore, decantation assists in the separation of soluble particles from liquid.

Disadvantages of Decantation

The following are some of the disadvantages of Decantation-

1. Because it is difficult to manually separate the mixture's components, all of them cannot be retrieved. Unless you use a centrifuge, waiting for the sediments to settle by gravity takes time.
2. Furthermore, since they are too light and do not remain at the bottom for long, light solid pollutants such as chalk powder cannot be removed from water using this approach.
3. Solids and liquids dissolved in the mixture cannot be separated. It cannot, for example, remove salt from water.

Difference Between Filtration and Decantation

The following are some of the differences between filtration and decantation-

While both filtration and decantation may be used to remove contaminants from liquids. Filtration is the direct separation of a whole solution through a filter, where the solid is trapped and the liquid passes through. It is not capable of separating two liquids. Decantation is the process of removing a liquid from solid contaminants that have fallen to the bottom of a container. Two liquids of differing densities that have been divided into two layers can be separated similarly by pouring the less dense liquid out.

Read more about the Difference Between Soaps and Detergents. 

Points to Remember

1. Decantation is a straightforward technique. It is feasible to accomplish it by hand. As a result, insoluble sediments or immiscible liquids may be readily separated.
2. Decantation is a typical process for purifying a liquid by separating it from an insoluble particle suspension or sediment.
3. Decantation may remove insoluble materials from liquids in addition to separating soluble particles. This requires letting the particles settle by gravity first, followed by emptying out the clear liquid.
4. If two liquids with different densities are immiscible, decantation can be employed to separate them.