There are five process for the coagulation of a colloidal solution:
- Addition of electrolytic solution: When electrolytic solution is added to a solution then the colloids particles attract the opposite changed electrolyte ions and neutralized. After neutralization colloid particles attract to each other and precipitated. Example: When NaCl electrolyte is added As2S3 negative solution then yellow precipitate is formed. Na+ neutralize the negative colloid particles in this case.
- Mixing of two solution having opposite charge: When two colloidal solution of opposite charged are mixed they neutralized to each other and precipitated forming large size particles. e.g. Fe(OH)3 and As2S3 solution mixing together are precipitated out.
- Vaporization: Lyophobic solutions are precipitated by vaporization. Because, at high temperature colloids particles are collided to each other more and more and form precipitation by closing together. e.g. Albumine is precipitated during heating in water.
- Electrophoresis: Applying electric field to the colloid particles are neutralized and closing together from precipitation.
- Persistent dialysis: Colloidal solution are stabilized due to the presence of few amount electrolytic solution. These electrolytic solution are removed by persistent dialysis and remaining portion is precipitated out.