ABSTRACT
Electromembrane processes have found application in removal of electrolytes from aqueous solutions using two oppositely charged (cation exchange membrane (CEM) and anion exchange (AEM) under an applied electric potential. Ever since its application in desalination of brackish water and industrial wastewater, it has been diversified into a series of different techniques based on the need for high quality process water including (i) electro-deionization, (ii) capacitive deionization and (iii) electrodialysis (ED) using bipolar membranes. All of these have been further diversified into various electromembrane techniques. Each electromembrane process might be quite different from the others, but the fundamental mass transfer driven by electric potential remains the same for all these processes. With increasingly stringent environmental stipulations, the ED process conditions are so designed that the treated water should be free from electrolytes. Reversal of ED phenomena by separating two streams of different concentrations using a polar membrane would generate potential gradient, i.e., source of energy. In this chapter, we take up both these aspects that will help us understand electromembrane process and energy generation.
