I wish to know the surface charge density of colloid particles in water by means of a practical method in lab. Please also suggest me some relevant papers. Thank you in advance.
Dear Ranjit De,
If your colloidal particles are believed to have a well defined surface functionality which is giving them a surface charge, then simple titrations can sometimes help.
If a particle was prepared with carboxylic acid groups on the surface of that particle, a simple acid/base titration would find percent ionization of the functional group at a given background ionic strength as a function of pH. So you have counted the ionic groups present and you measure the surface area of the particle via a particle sizing technique. Similar titrations exist for cationic surface groups.
Do keep an eye out for any serum phase acids/bases you might have left in your colloid -- you may need to sediment the colloid and then remove the serum to successfully titrate the colloid.
Best regards,
Mike B.
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