CAPACITIVE DEIONIZATION OF NH4CLO4 SOLUTIONS WITH CARBON AEROGEL ELECTRODES

A process for the capacitive deionization of water with a stack of car bon aerogel electrodes has been developed by Lawrence Livermore Nation al Laboratory (LLNL). Unlike ion exchange, one of the more conventiona l deionization processes, no chemicals are required for regeneration o f the system. Electricity is used instead. An aqueous solution of NH4C lO4 is pumped through the electrochemical cell. After polarization, NH 4+ and ClO4- ions are removed from the water by the imposed electric f ield and trapped in the extensive cathodic and anodic double layers. T his process produces one stream of purified water and a second stream of concentrate. The effects of cell voltage, salt concentration, and c ycling on electrosorption capacity have been studied in detail.