Chapter two - Fundamentals of electrochemical membrane technology

Abstract

The electrochemical membrane technology (EMT) knowledge comprises the fundamentals of basic theories and mechanisms, including electrokinetic phenomena of ions/colloids, ion transport in nanopores, electrical double layer (EDL) formation on electrified membrane (EM) surfaces, and polarization effect of organic molecules under an electric field (EF), which is summarized in this chapter. The modified migration of charged ions/colloids under the EF can be utilized to enhance membrane separation and antifouling performance. When an EM is employed as an electrode, the influence of the Donnan effect on retaining contaminants during the filtration process can be significantly strengthened, in which the modulated EDL formed under applied bias plays an important role. In addition, in situ electrochemical oxidation reactions on the EMs can lead to organic foulant degradation and thus alleviate membrane fouling. The polarization of organic molecules induced by the EF can contribute to regulating the cake layer structure through orthokinetic coagulation, which promotes the formation of a dynamic membrane to prevent membrane fouling and increase retention performance. Finally, challenges of and perspectives for future EMT studies are discussed. Future research on the fundamentals in EMT must focus on the development of an in situ characterization methodology for the EM filtration process, the modification of the basic theory that describes the EDL structure on EM surfaces, and the tailoring of the design principles of EM modules for practical applications.