Electro precipitation of smoke – The smoke is led through a chamber containing plates having a charged opposite to that carried by smoke particles. The particles on coming in contact with these plates lose their charge and get precipitated. The particles settle down on the floor of the chamber. The precipitator is called Cottrell precipitator.
Purification drinking water – Alum is added to impure water to coagulate the suspended impuritiesand make water fit for drinking.
Medicines – Most of the medicines are colloidal in nature. Colloidal medicines are bmore effective because they have a larger surface area and are more easily absorbed by the body. Eg- Argyrol is a silver sol used as an eye lotion, milk of magnesia is used to cure stomach disorders
Tanning – Animal hides are colloidal in nature. When a hide that has positively charged particles is soaked in tannin/chromium salts, which contains negatively charged particles , mutual coagulation takes place. This results in the hardening of leather. This process is termed as tanning.
Cleansing action of soaps- already explained
Photographic plates and films – Photographic plates and films are prepared by coating an emulsion of the light sensitive silver bromide in gelatin over glass plates or celluloid films.
Rubber industry- Latex is a colloidal solution of rubber particles which are negatively charged. Rubber is obtained by coagulation of latex.
Industrial products- Paints inks, synthetic plastics, rubber, cement, graphite lubricants are all colloids