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 Dr. Christian, Thank you so much for kind help. I shall look into your advice carefully and consult suggested papers, if required, I may get back to you again. Thank you once again.
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.