ELECTROKINETIC MEASUREMENTS ON POROUS POLYSULFONE MEMBRANES

The surface properties of porous ultrafiltration membranes were determ ined by means of the streaming potential. The membranes were prepared from chemically modified polysulfone through a phase inversion process . The chemical reactions were carried out in such a way that the resul ting polysulfone either was fitted out with chloromethyl substituents or with quaternary ammonia groups. Due to this, the surface of the mem branes cast from these materials were either neutral or positively cha rged. In aqueous solution, ion adsorption as well as dissociation can occur at the surface of the membranes. This can be demonstrated by str eaming potential measurements at different pH values, but constant ion ic strength. From the calculated zeta potential using a recently devel oped model, evidence can be given on the dissociation constants of aci dic and basic functional groups on the surface of the membranes and on the amount of charges within the shear plane adjacent to the membrane . Using solutions which contained surfactants, qualitative information on the amount of charges within the capillaries of the membrane can b e obtained. In the range from 20 to 70-degrees-C no temperature depend ency of the zeta potential could be observed.