Applications of Colloids:

1. Formation of Delta:  Deltas are formed at the river mouth. This is because river water is a negatively charged colloid of sand particles. When this water enters into sea, the positive ions present in sea water coagulate the colloidal solution of sand and so the particles settle down. This will result in the formation of delta.


2. Electrical precipitation of smoke (Cottrell precipitation): Smoke is a colloidal solution of carbon, arsenic compounds, dust particles etc. in air. The smoke before coming out of the chimney is passed through a chamber (Cottrell precipitator) containing plates having a charge opposite to that of smoke particles. Thus, neutralization of charges occurs and the particles settle down and pure air flows out of the chimney.


3. Purification of drinking water: The water obtained from natural sources often contains suspended impurities. In order to coagulate these impurities, alum is added to water. The positive ions present in alum neutralize the suspended impurities and hence get purified.

4. Medicines: Most of the medicines are colloidal in nature. This is because they have large surface area and are therefore easily assimilated. For example, argyrol is a silver sol used as an eye lotion. Colloidal antimony is used in curing kalaazar. Colloidal gold is used for intramuscular injection. 

5. Tanning:  Animal hides are colloidal in nature. When a hide, which has positively charged particles, is soaked in tannin (which contains negatively charged colloidal particles) mutual coagulation takes place. This results in the hardening of leather. This process is termed as tanning.

 6. Photographic plates and films: Photographic plates or films are prepared by coating an emulsion of the light sensitive silver bromide in gelatin over glass plates or celluloid films.

7. Rubber industry: Rubber latex is a colloidal solution of rubber particles which are negatively charged. Rubber is obtained by coagulation of the latex.

8. Food articles: Milk, butter, halwa, ice creams, fruit juices, etc., are all colloids in nature.


9. Blood: Blood is a colloidal solution of an albuminoid substance. When alum and ferric chloride (FeCl3) solution are added to blood, then coagulation of particles take place which results in clotting of blood.


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