(220e) Desalination Shocks In Cross Flows

Recent experimental and theoretical studies have shown that surface conduction provides an effective mechanism for sustaining overlimiting current in microstructures. It is well understood that passing current through microstructures next to a selective boundary, such as a membrane, gives rise to the concentration polarization phenomenon, through which asymmetric repelling/selection by the boundary initiates a depletion region next to the boundary. For microstructures with high enough surface to volume ratios, such as microporous media or thin microchannels, this initial depletion can induce a long-range nonlinear wave propagating away from the interface faster than diffusion. Propagation of this wave (desalination shock) leaves behind an ultra pure region of bulk electrolyte through which current is dominantly supported by surface conduction. In our presentation we will discuss behavior of desalination shocks in multi-dimensional systems where cross flow, tangential to the membrane, is present acting to distort the shape of the shock. We will discuss advantages of such systems for desalination and water purification.