Surface characterization of hemodialysis membranes based on electrokinetic measurements

Hemodialysis membranes were characterized by means of streaming potential measurements. By variation of the concentrations of different ionic species in the measuring solutions surface potential determining processes can be distinguished: The investigated materials (cellulose derivates) yield surface charges mainly from preferred adsorption of ions. A thermodynamic model of the electrochemical double layer according to STERN (1) was applied to quantify that processes: the resulting set of parameters provide a conjunction between chemical surface properties and the observed interfacial charging processes. Streaming potential measurements can be used for the in situ characterization of the adsorption of biologically relevant molecules like proteins and polysaccharides onto membrane materials. The results given here show the alteration of interfacial properties of different cellulosic membranes through adsorption of human serum albumin and fibrinogen in single, sequential and competitive adsorption.