Question

Describe some of the important applications of colloids.

Answer 1

1. Food stuffs and medicines: Many food items like milk, butter, ice cream, and bread are colloidal in nature, where milk is an emulsion of butterfat in water stabilized by proteins, and ice cream is a dispersion of ice particles in cream. Colloidal medicines such as penicillin and ointments are more effective because they are easily absorbed by the body.
2. Purification of water: Colloidal impurities in impure water are coagulated by adding electrolytes like potash alum, which neutralizes their charge, causing them to aggregate and be removed by filtration.
3. Sewage disposal: Colloidal particles of dirt in sewage, carrying electrical charges, are removed by electrophoresis, where these particles migrate to electrodes and coagulate, aiding sewage treatment.
4. Smoke precipitation: Smoke consists of charged colloidal carbon particles, which are removed using a Cottrell precipitator that applies high voltage to attract particles to oppositely charged plates, reducing air pollution.
5. Artificial rain: Clouds are colloidal systems of water droplets carrying electrical charges; spraying oppositely charged dust neutralizes these charges, causing droplets to coalesce and fall as rain.
6. Rubber industry: Latex is a colloidal emulsion of rubber particles in water, from which rubber is obtained by coagulation and vulcanization.
7. Leather tanning: Positively charged colloidal particles in raw hides coagulate with negatively charged tanning agents, hardening them into leather.
8. Cleansing action of soaps: Soap solutions form colloidal emulsions with grease and dirt, making them water-soluble for easier washing.
9. Smoke screens: Colloidal dispersions of titanium oxide particles are used in smoke screens to hide troop movements in chemical warfare.
10. Preparation of nano-materials: Colloids serve as precursors for the synthesis of nano-sized catalysts.
11. Road building: Asphalt emulsified in water is used for road construction without needing to melt asphalt.
12. Metallurgical operations: Froth flotation, using emulsified pine oil, is employed for concentrating metal ores by selective adhesion of impurities.