Peptization

As peptization (Greek ) the re- dissolution of a flocculated or coagulated colloid is called. It is thus converted into a colloidal solution (sol).

The reverse process is called coagulation, which by the aggregation of colloidal particles large agglomerates.

Coagulation of colloids or disperse systems of coarser as suspensions can be prevented by the addition of peptizers. This is to ions with strong electrical charge, such as citrates, tartrates, oxalates or diphosphates. You are adsorbed to the particle surface of charged particles and can compensate for its Nernst potential. It is here to repolarization, ie to a sign inversion of the electric potential at the shear plane ( zeta potential). This results in an electrostatic repulsion between the particles, whereby the aggregation is suppressed.

Peptidizers are used as dispersants for example in pharmaceutical technology ( Galenic ) to produce stable suspensions.

With slightly soluble ( lyophilic ) colloids peptization can also be achieved by dilution or by increasing the temperature.