7.4 Purification of Colloidal System

2.1 Characteristics of Adsorption
2.2 Types of Adsorption

4.1 Freundlich adsorption isotherm
4.2 The Langmuir adsorption isotherm

7.1 Different Colloidal Systems
7.2 Classification of Colloidal System
7.3 Preparation of Colloidal System
7.4 Purification of Colloidal System
7.5 Properties of colloidal system

8.1 Protective colloids

9.1 Foams
9.2 Applications of colloids and emulsions

10.1 Positive and negative catalysis
10.2 Types of catalysis

12.1 Characteristics of Enzymes
12.2 Mechanism of enzyme catalysis
12.3 Autocatalysis
12.4 Induced catalysis

Dialysis may be defined as the process of separating a crystalloid from a colloid by diffusion or filtration through a fine membrane, the membrane (or apparatus) used for the purpose is known as dialyser.

The process of dialysis can be quickened by using hot water (hot dialysis) or by applying an electric field (electrodialysis).

Sol particles directly pass through ordinary filter paper because their pores are larger than size of sol particles. But if the pores of the ordinary filter paper are made smaller by soaking the filter paper in a solution of gelatin or colloidion and subsequently hardened by soaking in formaldehyde, the treated filter paper may retain colloidal particles and allow the true solution particles to escape.

Such filter is known as ultrafilter and the process of separating colloids by using ultrafilters is known as ultrafilitration.

The sol particles are prevented from settling out under the action of gravity by kinetic imparts of the molecules of the medium. However, the setting force can be enhanced by using high speed centrifugal machines having $15,000$ or more revolutions per minute.

Such machines are known as ultracentrifuges.