Application of Adsorption

Applications of Adsorption

Some of the important applications of adsorption are given below:

1) In gas masks

Activated charcoal or a mixture of adsorbents is generally used in gas masks to adsorb poisonous and toxic gases from air.

These masks are commonly used by the miners because there are poisonous gases like CO, CH₄ etc. in the atmosphere in the coal mines. Therefore, these masks help to purify the air for breathing.

2) In dyeing of cloth

Mordants such as alums are used in dyeing of cloth. They adsorb the dye particles which, otherwise, do not stick to the cloth.

3) In Dehumidizers for control of humidity

Silica and aluminium gels are commonly used to adsorb humidity or moisture from air. 

4) Removal of colouring matter from solutions

Many substances such sugar, juice and vegetable oils are coloured due to the presence of impurities. They can be decolourised by placing in contact with adsorbents like activated charcoal or fuller’s earth. This method is used in the manufacture of cane sugar. 

5) Heterogeneous catalysis

Adsorption of reactants on the solid surface of catalysts increases the rate of reaction. The metals such as Fe, Ni, Pt, Pd, etc, are used in the manufacturing process.

Manufacture of ammonia using iron as catalyst (Haber process), manufacture of sulphuric acid by contact process and use of finely divided nickel in the hydrogenation of oils are excellent examples of heterogeneous catalysis.

6) In ion-exchange resins

The organic polymers containing groups like – COOH,- SO₃H and- NH₂, etc. possess the property of selective adsorption of ions from solutions. These are quite useful in the softening of water.

7) In adsorption Indicators

Many adsorption indicators are being used in volumetric analysis. For e.g., dyes such as eosin and fluorescein are used as adsorption indicators. In these methods, the dyes are adsorbed on the surfaces of certain precipitates (such as silver halides) which give characteristic colour at the end point.

8) In qualitative analysis

Certain qualitative tests such as the lake test for the confirmation of Al³⁺ ions are based upon adsorption i.e., Al(OH)₃ , has the capacity to adsorb the colour of blue litmus from the solution.

9) Production of high vacuum

The adsorption of air in liquid air helps to create a high vacuum in a vessel. This process is used in high vacuum instruments as Dewar flask for storage of liquid air or liquid hydrogen. The remaining traces of air can be adsorbed by charcoal from the vessel evacuated by a vacuum pump to give a very high vacuum.

10) Separation of inert gases

Due to the difference in degree of adsorption of gases by charcoal, a mixture of noble gases can be separated by adsorption on coconut charcoal at different temperatures.

11) In froth floatation process

A low grade sulphide ore is concentrated by separating it from silica and other earthly matter by adsorption using pine oil and frothing agent. 

12) In curing diseases

A number of drugs are used to kill the germs by getting adsorbed on them.

13) Chromatographic analysis

The chromatographic technique for purification used in analytical and industrial fields is based on the phenomenon of adsorption.