courtesy of DataPhysics

Ion-exchange membranes are widely used in numerous applications, such as water treatment, chemistry, electrolysis, sensorics and other fields. A good ion transfer selectivity of the ion-exchange membrane is highly important for all of these applications. The charge structure and composition of ion-exchange membranes has a strong influence on the mobility of different ions or molecules and thus governs the selectivity of ion transport processes through the membrane.[1] Therefore, it is of great importance to have a good technique to characterise the charged surface functionalities of ion-exchange membranes.

A powerful technique to evaluate charged surface functionalities is the measurement of the zeta potential, that is, the electric potential of solid surfaces in contact with an electrolyte solution. With this information it is possible to better understand the dissociation state of functional groups on the surface, and conclude the electrostatic interactions that will occur with other materials such as charged particles. The new Zeta Potential Analyzer ZPA 20 from DataPhysics Instruments (Fig. 1) measures the zeta potential of fibres, powders and plate shaped surfaces by means of a novel bidirectional oscillating streaming potential or streaming current technique. In this application note, we study the functional groups of different ion-exchange membrane surfaces with the ZPA 2. Read the application note here