Chapter 3: Electromembranes for Water Treatment Driven by Electricity
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Published:29 Nov 2021
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Special Collection: 2021 ebook collectionSeries: Chemistry in the Environment
J. Liao, W. Shi, and J. Shen, in Advances in Functional Separation Membranes, ed. X. Li, J. Lin, and S. Zhao, The Royal Society of Chemistry, 2021, ch. 3, pp. 57-82.
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Electromembranes or “charged membranes”, representing ion-exchange membranes (IEMs), have been used in numerous processes, which are rather different in their basic concept, their practical applications, and their technical relevance. The IEM-based technologies, such as common electrodialysis (ED), bipolar membrane electrodialysis (BMED), capacitive deionization (CDI), and continuous electrodeionization (EDI), have further extended the range of applications of electromembrane processes beyond their traditional use in water treatment. The term “electromembrane process” is used to describe an entire family of processes that can be quite different in their basic concept and their application. But they are all based on the coupling of mass transport with an electrical current through ion perm-selective membrane. Electromembranes are used to remove ionic components such as salts from electrolyte solutions or to produce certain compounds such as NaOH and Cl2 from NaCl solutions. This chapter is concentrated mainly on technically relevant electromembranes for common electrodialysis, BMED, CDI, MCDI, and EDI, related to water treatment driven by electricity. To better illustrate the electromembrane process, some investigations on electrode, spacer, and setup used for electrodialysis have been included. In addition, two typical water treatment cases are also taken as examples.