Abstract
Research on electrochemical impedance spectroscopy (EIS) for reverse osmosis (RO) membranes is progressing intensively by several groups in two major themes. One of them is the ion permeability characterization of the membrane. Since EIS measures the conductivity using the ions themselves as a probe, it can be said that the permeation behavior of the ions in the membrane is directly observed. The second major theme of EIS is the development of a real–time monitoring system to detect fouling in its earliest stage. By using equivalent circuit analysis according to the Maxwell–Wagner model, the index most related to the occurrence of fouling is extracted and fouling process is monitored. In this paper, these techniques are briefly reviewed and an EIS analysis method for the active layer of RO membranes that the author is advancing is also discussed.
