Electrodialysis applications for pollution prevention in the chemical processing industry

This paper reviews recent advances in the application of electrodialysis (ED) to chemical recovery and reuse and chemical separations and reactions for pollution prevention. Numerous green applications have been investigated since the early days of ED, when the dominant applications were for salt production from seawater and potable water production. New applications include inorganic acid, base and salt production, recovery and purification, organic acid production, organic separations from inorganic brine streams, low temperature and pressure organic reactions, and others. Preliminary analysis of the ED system electrical power costs to achieve these applications indicate that some salt recovery and most organic separation and reaction schemes, may be economically attractive, at least from an energy usage standpoint. The concentration increases and chemical recovery levels are discussed for a number of cases. The separation potential and system stability for nonaqueous applications are also highlighted. All these factors lead to the conclusion that ED has reached a level where it deserves to be considered as a separation or reaction unit operation in the "green" process of the future.