On the drying out of bipolar membranes

Ora Kedem , Andrea Ghermandi , Rami Messalem

Abstract

The maximum current density that can be achieved in bipolar membrane electrodialysis is limited by the sharp increase in resistance that is experienced when the water content at the membrane interface is not adequately replenished and the membranes dry out. In this paper we show how the water content near the interface depends on the properties of the membranes. A water retaining parameter is introduced, which characterizes the thermodynamic properties of the membrane material and may be used to guide the choice of polymers for mitigation of the dry-out problem.

Key Words

bipolar membrane; dry-out; current-voltage curve; electro-osmosis; water absorption

Address

1
Ora Kedem — Weizmann Institute of Science, Rehovot 76100, Israel; 2
Andrea Ghermandi — Dept. of Natural Resources and Environmental Management, University of Haifa, 31905 Haifa, Israel; 3
Rami Messalem — Zuckerberg Inst. for Water Research, Ben Gurion University of the Negev, 84105 Beer-Sheva, Israel

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