(161a) Nonlinear Electrokinetics in Porous Media

The classical theory of electrokinetic phenomena in porous media assumes linear response to a small voltage, where the electrolyte concentration is only weakly perturbed. This talk will describe three new nonlinear electrokinetic phenomena arising in water deionization: (i) Current induced discharge of porous membranes, which leads to over-limiting current carried by co-ions and water ions (ii) time-dependent ion selectivity of capacitive charging in porous electrodes, which can be exploited for batch separations of multicomponent electrolytes, and (iii) shock electrodialysis in porous filters, due to surface conduction and electro-osmotic flow, which can be harnessed for continuous separation of salt and co-ionic particles to produce fresh water. Both theory and experiments will be discussed, as well as engineering applications to industrial wastewater treatment, such as produced water from hydraulic fracturing of oil shales ("fracking"). 

[Joint work with D. S. Deng, Sven Schlumpberger, Vicki Dydek, Ali Mani, Boris Zaltzman, Isaak Rubinstein, Mathias Andersen, Henrik Bruus, Michiel van Soestbergen, and P. Maarten Biesheuvel.]