Innovations in electromembrane processes

Abstract

Electromembrane processes are increasingly important group of separation methods, widely used for removal of charged components from solutions. It is a growing field of research with a plethora of both existing and still developed applications. The separation is based on ion migration across the charged membranes (a polymeric matrix with fixed charged groups, counterbalanced with mobile counter-ions), placed in the electric field. This paper presents the main electromembrane processes: electrodialysis (ED), electrodialysis reversal (EDR), electrodialysis with bipolar membrane (EDBM), electrodeionization (EDI), membrane capacitive deionization (MCDI), reverse electrodialysis (RED). We present the common applications of electromembrane processes and discuss the physical basis of the electromembrane processes. The most important parameters of the ion-exchange membranes are discussed, as well as the novel approaches towards mitigation of scaling, enhancement of mass transfer, decreasing the concentration polarization, and new hybrid electromembrane processes. Critical analysis of the possibility of energy production by reverse electrodialysis is presented.