Question

What are the different methods applied for the purification of colloidal solutions ?

Answer 1

Peptization and electrical disintegration are the methods for the preparation of coloids.

Colloidal sols, prepared ​by various methods​ are impure and contain impurities of electrolytes and other soluble substances.​

Important methods of removal ​of soluble impurities​ are
1. Dialysis
2. Electrodialysis
3. Ultra Filtration

Dialysis: Process of removing a dissolved substance from a colloidal solution​ by means of diffusion through a suitable membrane​.

Electrodialysis: This method is same as dialysis but electric field is applied to make the process faster​.

Ultra Filtration: Process of separating ​colloidal particles​ from solvent and soluble solutes​ by specially prepared filters. These filters should be permeable to all substances except the colloidal particles​.