. Discuss the following methods are commonly used to purify a colloidal solution
The following methods are commonly used to purify a colloidal solution.
By this method soluble impurities are removed from colloidal solution by taking colloidal solution in a bag made of semipermeable membrane like parchment paper or cellophane and dipping it in water. The molecular and ionic impurities being small in size pass through the pores of semipermeable membrane. The colloidal particles are large enough so that they cannot pass through the pores.
Movement of the ions through the membrane can be expedited by the application of electric field through the two electrodes. This method is called electrodialysis.
iii. ULTRA CENTRIFUGATION
In this method, the colloidal solution is placed in a high speed ultracentrifuge. On centrifuging, the colloidal particles settle down. The impurities remain in the dispersion medium and are removed by decantation. The settled colloidal particles are shaken with water containing peptizing agent to form the colloidal solution again.