SURFACE CHARACTERIZATION OF HEMODIALYSIS MEMBRANES BASED ON ELECTROKINETIC MEASUREMENTS

Hemodialysis membranes were characterized by means of streaming potent ial measurements. By variation of the concentrations of different ioni c species in the measuring solutions surface potential determining pro cesses can be distinguished: The investigated materials (cellulose der ivates) 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 properti es and the observed interfacial charging processes. Streaming potentia l measurements can be used for the in situ characterization of the ads orption of biologically relevant molecules like proteins and polysacch arides onto membrane materials. The results given here show the altera tion of interfacial properties of different cellulosic membranes throu gh adsorption of human serum albumin and fibrinogen in single, sequent ial and competitive adsorption.