Electromembrane Processes: Basic Aspects and Applications

Abstract

Electromembrane processes, such as electrolysis, electrodialysis, and diffusion dialysis, have experienced a steady but moderate growth since they made their first appearance in industrial-scale applications about 30 years ago. Currently, the desalination of brackish water and the chlorine–alkaline electrolysis are the dominant applications of electromembrane processes. However, interest in other processes such as diffusion dialysis or continuous electrodeionization is rapidly growing. New applications of ion-exchange membranes in fuel cells and catalytic membrane reactors have recently been identified. However, today’s ion-exchange membranes and processes have still severe technical and commercial limitations and there is a need for further basic and applied research. In this chapter, some fundamental aspects of electromembrane processes, such as the function of ion-exchange membranes and the mass transport in solutions and membranes, are reviewed. The principles of today’s most relevant electromembrane processes are described and their technical and commercial limitations pointed out. More recently developed products and processes based on ion-exchange membranes, such as fuel cells, are discussed and their present and potential future applications indicated.