Physics – Fluid Dynamics
Scientific paper
2011-08-03
Physics
Fluid Dynamics
14 pages, 7 figures
Scientific paper
Salt transport in bulk electrolytes is limited by diffusion and convection, but in microstructures with charged surfaces (e.g. microfluidic devices, porous media, soils, or biological tissues) surface conduction and electro-osmotic flow also contribute to ionic fluxes. For small applied voltages, these effects lead to well known linear electrokinetic phenomena. In this paper, we predict some surprising nonlinear dynamics that can result from the competition between bulk and interfacial transport at higher voltages. When counter-ions are selectively removed by a membrane or electrode, a "desalination shock" can propagate through the microstructure, leaving in its wake an ultrapure solution, nearly devoid of co-ions and colloidal impurities. We elucidate the basic physics of desalination shocks and develop a mathematical theory of their existence, structure, and stability, allowing for slow variations in surface charge or channel geometry. Via asymptotic approximations and similarity solutions, we show that desalination shocks accelerate and sharpen in narrowing channels, while they decelerate and weaken, and sometimes disappear, in widening channels. These phenomena may find applications in separations (desalination, decontamination, biological assays) and energy storage (batteries, supercapacitors) involving electrolytes in microstructures.
Bazant Martin Z.
Mani Ali
No associations
LandOfFree
Desalination shocks in microstructures does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Desalination shocks in microstructures, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Desalination shocks in microstructures will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-664335