Journal of membrane science vol:188 issue:1 pages:129-136
In this study, several methods were used to determine the charge of commercially available nanofiltration membranes, and were compared. First the ion-exchange capacity was determined by titration, this method is able to distinguish between positively and negatively charged Functional groups on the membrane. Secondly, measurements of the streaming potential gave a value fur the charge density at the exterior membrane surface, the effect of the pH of the solution on the membrane charge was studied. Finally, measurements of the membrane potential allowed to evaluate the total membrane charge density.