what is coagulation. methods of coagulation of lyophilic sols
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Answer:
The coagulation of a sol can be carried out by different methods as follows:
(1) By electrophoresis : In the electrophoresis process, the colloidal particles migrate to the oppositely charged electrodes in the presence of an applied electric field and get discharged. These particles eventually aggregate and coagulate.
(2) By mixing oppositely charged colloidal sols : When two sols carrying opposite charges are mixed, both the sols get mutually neutralised and coagulate. For example, addition of positively charged colloidal solution of Fe(OH), to an equal amount of negatively charged sol of As Sz causes coagulation of both the sols.
(3) By boiling the sol : When the sol is boiled, the adsorbed ions on colloidal particles removed and neutral particles undergo rapid collisions in dispersion medium and coagulate.
(4) By persistent dialysis : On persistent dialysis,.the adsorbed ions on colloidal particles are.removed. The colloidal particles then become unstable and finally precipitate.
(5) By addition of electrolytes : When an excess of electrolyte is added, the colloidal particles undergo coagulation.