What is "peptization" ?

Peptization may be defined as the process of converting a precipitate into colloidal sol by shaking it with dispersion medium in the presence of a small amount of electrolyte. The electrolyte used for this purpose is called peptizing agent. This method is applied, generally, to convert a freshly prepared precipitate into a colloidal sol. 

For example, when freshly precipitated Fe(OH)3 is shaken with aqueous solution of FeCl3(peptizing agent) it adsorbs Fe+3 ions and thereby breaks up into small – sized particles.

Why medicines are more effective in colloidal state?

A colloidal state has larger surface area of sol particles and this shows more effective adsorption. Thus medicines in colloidal state are more effectively absorbed and give better results.

What is Associated Colloids (Micelles) ?

There are some substances which at low concentrations behaves as normal, strong electrolytes but at higher concentrations exhibit colloidal  behaviour due to the formation of aggregated particles. The aggregated particles thus formed are called micelles. These are also known as associated colloids. 

The formation of micelles take place only above a particular temperature called kraft temperature (Tk) and above a particular concentration called critical micelle concentration (CMC). On dilution, these colloids revert back to individual ions. Surface active agents such as soaps and synthetic detergents belong to this class. For soaps, the CMC is -10-4

to 10-3 molperL. 

These colloids have both lyophobic and lyophilic parts. Micelles may contains as many as 100 molecules or more.