(136a) Shock Electrodialysis for Ion-Selective Water Purification

Shock electrodialysis is an emerging method of water desalination, based on separating fluid streams on either side of a deionization shock wave propagating through a charged porous medium under over-limiting current. This talk will introduce the basic physics of shock ED and demonstrate promising new applications in water treatment. For dilute feed streams, shock ED is capable of complete (>99.99%) salt removal with high (>85%) water recovery, which we apply to the removal of cobalt and cesium ions from nuclear waste. High (>90x) selectivity for multivalent ions is also illustrated by the continuous removal of lead and magnesium from dilute sodium chloride solutions. High selectivity for toxic metal ions at low salinity leads to ultra-low electrical energy cost (~$0.01/m³), which could lead to a practical solution to purify drinking water from corroded pipes or contaminated sources. This work also raises theoretical questions about extreme nonlinear electrokinetic phenomena in porous media, far above the diffusion-limited current.