Capacitive deionization (CDI) is an emerging water treatment technology that uses electrophoretic driving forces to achieve desalination. During CDI,
ions are adsorbed onto the surface of porous electrodes by applying a low voltage electric field. The negative electrodes attract positively charged ions
such as calcium, magnesium, and sodium; simultaneously, the positive electrodes attract negatively charged ions such as chloride, nitrate and sulfate.
Unlike ion exchange processes, no additional chemicals are required for regeneration of the electrosorbent in this system. Eliminating the electric field
allows ions to desorb from the surface of the electrodes and regenerates the electrodes. There are a variety of electrode materials and configurations to
enhance performance. Optimized carbon aerogel is an ideal electrode material because of its high electrical conductivity, high specific surface area, and
controllable pore size distribution. Previous studies show that CDI technology is cost competitive with reverse osmosis processes only at a low feed TDS
concentration range (<3,000 mg/L) due to the high cost of CDI modules with increased feed water TDS concentrations. During laboratory and field treatment of
sandstone-produced water with a commercial CDI system (Electronic Water Purifier (EWP)), no electrode deterioration was observed and the CDI process exhibited
much less fouling/scaling propensity compared to RO/NF.