1. Tanning of leather:
Skin and hides are protein containing positively charged particles which are coagulated by adding tannin to give hardened leather for further application. Chromium salts are used for tanning of leather. Chrome tanning can produce soft and polishable leather.
2. Rubber industry:
Latex is the emulsion of natural rubber with negative particles. By heating rubber with sulphur, vulcanized rubbers are produced for tyres, tubes etc.
3. Sewage disposal:
Sewage containing dirt, mud and wastes dispersed in water. Th e passage of electnic current deposits the wastes materials which can be used as a manure.
