Pore-surface characterization of poly(acrylonitrile) membrane having amphoteric charge groups by means of zeta potential measurement

Pore-surface characteristics of poly(acrylonitrile)-based porous membranes having amphoteric charge groups were investigated by zeta potential obtained from streaming potential measurements. The amphoteric-charged pore surface was theoretically examined by a single-acid, single-base site dissociation model, whose model is based on the assumption that the surface charge arises only from the protonation and deprotonation of the charged surface groups. From the theoretical approach, some characteristic parameters of the amphoteric pore surface such as the isoelectric point, dissociation constant, apparent site density of each acidic and basic group, and acid-to-base ratio were successfully determined. These parameters were changed in response to the variation of the feed monomer ratio. This approach can be expected to provide useful information concerning the pore-surface charge of an amphoteric-charged membrane. (C) 1999 Elsevier Science B.V. All rights reserved.