Chronopotentiometry and impedancemetry of homogeneous and heterogeneous ion-exchange membranes

Abstract

It is known that the behavior of a membrane with homogeneous and heterogeneous surface under the same current density is different. In order to find out this difference, a two-dimensional non-stationary model of mass transfer through electrically inhomogeneous surface of ion-exchange membrane under direct current is proposed. In this paper, the general formulation of the boundary conditions at the conductive sections has the form of the integral function of the local current density. The problem was solved by applying an electric current stream function, which is quite similar to the stream function in hydrodynamics. For the first time, it is proved that the distribution of current lines over the conductive sections of the membrane is not uniform. It is shown experimentally and theoretically that the shape of chronopotentiograms and electrochemical impedance spectra changes with changing conductive portion of the ion-exchange membrane surface.

Keywords:

• Mass transfer
• Electromembrane system
• Purification of water solutions
• Water treatment
• Mathematical modeling
• Partial differential equations
• Electrochemical impedance spectroscopy
• Chronopotentiometry

Acknowledgments

Part of the work was carried out within the framework of joint French-Russian laboratory “Ion-Exchange Membranes and Related Processes.” The authors are grateful to the CNRS, RFBR (Grant No. 14-08-31462-mol-a, 14-08-31451-mol-a), and FP7Marie Curie Actions “CoTraPhen” Project PIRSES-GA-2010-269135.

Notes

Presented at the MELPRO 2014 conference Membrane and Electromembrane Processes, 18–21 May 2014, Prague, Czech Republic