What are different methods of peptization ?

Explanation

Peptization : Peptization is the process of converting freshly prepared precipitates into colloidal solution. Peptization can be achieved as follows:
i) By adding excess electrolyte to freshly prepared precipitates.
`Fe (OH)_2 + FeCl_3 to [Fe(OH)_3Fe]^(3+) + 3Cl^-`
ii) By adding another colloids. For example, lamp black is peptized by adding gums.
iii) By washing precipitate. For example, CuS and `BaSO_4` on washing continuously pass into colloidal form.
iv) By adding organic solvents. For example, a colloidal solution of cellulose nitrate is prepared in ethyl alcohol and ether. The product so obtained is commercially known as colloidion.