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arXiv · 1403.4421

Equilibrium Electro-osmotic Instability

Isaak Rubinstein·Boris Zaltzman
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Abstract

Since its prediction fifteen years ago, electro-osmotic instability has been attributed to non-equilibrium electro-osmosis related to the extended space charge which develops at the limiting current in the course of concentration polarization at a charge-selective interface. This attribution had a double basis. Firstly, it has been recognized that equilibrium electro-osmosis cannot yield instability for a perfectly charge-selective solid. Secondly, it has been shown that non-equilibrium electro-osmosis can. First theoretical studies in which electro-osmotic instability was predicted and analyzed employed the assumption of perfect charge-selectivity for the sake of simplicity and so did the subsequent numerical studies of various time-dependent and nonlinear features of electro-osmotic instability. In this letter, we show that relaxing the assumption of perfect charge-selectivity (tantamount to fixing the electrochemical potential in the solid) allows for equilibrium electro-osmotic instability. Moreover, we suggest a simple experimental test for determining the true, either equilibrium or non-equilibrium, origin of electro-osmotic instability.

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Isaak Rubinstein, Boris Zaltzman. 2014-03-18. Equilibrium Electro-osmotic Instability. https://doi.org/10.1103/physrevlett.114.114502

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