Overlimiting current in a microchannel
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.
Cite
@article{arxiv.1108.2325,
title = {Overlimiting current in a microchannel},
author = {E. Victoria Dydek and Boris Zaltzman and Isaak Rubinstein and D. S. Deng and Ali Mani and Martin Z. Bazant},
journal= {arXiv preprint arXiv:1108.2325},
year = {2015}
}
Comments
8 pages, 8 figs