AWWA MTC61225

In this work the authors explore the use of electrochemical impedance spectroscopy (EIS) as a tool for characterizing membrane surface chemistry. The surface potentials of iron-based and aluminum-based nanostructured ceramic membranes were characterized using EIS, and compared with measurements of electrophoretic mobility and acid/base titration. Protonic conductivity was measured using EIS in a two-electrode mode at a frequency range of 0.01 Hz to 100 kHz. Electrophoretic mobility measurements were performed at various ionic strength and pH for suspended ceramic nanoparticles sintered at different temperatures. The isoelectric point determined from electrophoretic mobility measurements and from titration methods were compared. The isoelectric point of membranes sintered at different temperatures agrees with the protonic conductivity measurement by EIS. Membranes with lower isoelectric point correspond to more surface hydroxyl groups available for proton transfer, which enhances its protonic conductivity. EIS is a simple and reliable method of providing information about the surface potential of ceramic membranes without damaging the membrane sample. Includes 2 references, figures.