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arXiv · 1108.2325

Overlimiting current in a microchannel

E. Victoria Dydek·Boris Zaltzman·Isaak Rubinstein·D. S. Deng·Ali Mani·Martin Z. Bazant
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Abstract

We revisit the classical problem of diffusion-limited ion transport to a membrane (or electrode) by considering the effects of charged side walls. Using simple mathematical models and numerical simulations, we identify three basic mechanisms for over-limiting current in a microchannel: (i) {\it surface conduction} carried by excess counterions, which dominates for very thin channels, (ii) convection by {\it electro-osmotic flow} on the side walls, which dominates for thicker channels and transitions to (iii) {\it electro-osmotic instability} on the membrane end in very thick channels. These intriguing electrokinetic phenomena may find applications in biological separations, water desalination, and electrochemical energy storage.

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E. Victoria Dydek, Boris Zaltzman, Isaak Rubinstein, D. S. Deng, Ali Mani, Martin Z. Bazant. 2011-08-11. Overlimiting current in a microchannel. https://doi.org/10.1103/physrevlett.107.118301

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