An alkaline stable anion exchange membrane for electro-desalination

Abstract

Anion exchange membrane (AEM) as a positively-charged polymer allows the transition of anions, block the cations, and has been widely used in the electro-desalination processes. Permselectivity, alkaline stability, and electric ohmic resistance on the AEM are critical issues determining the final desalination efficiency in an electro-desalination process. Here in this work, the AEM with sound desalination and alkaline stable character was fabricated from the aspect of functional group optimization, i.e., introduce into the 2, 6-dimethyl-1, 4-phenylene oxide (PPO) polymer matrix as the alternative of the conventional. The 1-naphthol derivatives, i.e., 2-[dimethylaminomethyl] naphthalen-1-ol, and 2,7-bis[dimethylaminomethyl] naphthalen-1-ol as the functional groups provide conjugated π-electron, which may increase the alkaline stability of the anion exchange membranes (AEMs), and thus guarantee its long-term stability when operating the electro-desalination process over the limiting current density condition. The innovative membranes perform lower area resistance 0.5–2.27 Ω cm2 and well stability in the alkaline circumstance. In comparison to the commercial membranes (Neosepta AMX, standard grade), the obtained membrane presented comparable electro-desalination performance. The results indicate AEMs that functionalized by 1-naphthol derivatives can be a promising candidate for electro-desalination processes.