Concentration polarization in ion-exchange membranes

Concentration polarization is the most constraining phenomenon for ion transport in a variety of electro-membrane processes. The development of concentration gradients at the interfaces between electrolyte solutions and membranes limits the maximum current that can flow within an electrochemical device and entails increased voltage drops. Although this phenomenon is inherent to the use of selective membranes, its negative effects on the current efficiency and energy consumption of electrochemical processes can be minimized by taking different actions, like modifying different components of electrochemical cells or implementing appropriate operating modes. In this chapter, the principles and equations that govern ion transport through ion-exchange membranes are treated, and new trends regarding mitigation strategies for concentration polarization are reviewed.