Electrified carbon nanotube membrane technology for water treatment

Current fallouts of environmental pollution call for advanced water purification techniques. Although electrochemical processes are promising solutions, their practical engineering application is still hampered by the lack of a design of robust and effective electrode materials offering efficient diffusive mass transport in traditional batch reactors. In this context, the design of the electrochemical membrane (EM) integrates the functions of electrochemistry and membrane separation, which provides a viable solution to these limitations with maximized liquid-catalysts contacting. The flow-through EM can boost the electrochemical reaction kinetics via the convection-enhanced mass transport, and with direct electrolysis degrading of foulants. This chapter aims to highlight the synergistic effect between membrane separation and electrochemistry toward the environmental applications using carbon nanotube (CNT) as a model EM material. The intriguing physicochemical characteristics of CNT-based EM materials coupled with the advanced reactor design provide promising solutions to the existing electrochemical water treatment strategies. We first summarize the fabrication protocols of CNT-based EM. We then focus on the delicate design of several different electrochemical filtration systems based on anodic oxidation or cathodic reduction reactions. The underlying working mechanism of each system is systematically elucidated and reviewed. The technological limitations and future perspectives toward practical applications in water treatment are discussed last.