Mussel-inspired sulfonated polydopamine coating on anion exchange membrane for improving permselectivity and anti-fouling property

Anion exchange membranes (AEMs) with high monovalent/multivalent anion perselectivity are essential for wide range applications (e.g., electrodialysis (ED)). In this work, we have proposed a facile surficial adhesive modification process to fabricate a highly permselective AEM for ED application. Firstly, a novel sulfonated dopamine (SDA) adhesive was synthesized, followed by coating this kind of polymer-like adhesive on commercial AEMs under alkaline and aerobic conditions. We have found that the SDA coating can significantly enhance the monovalent permselectivity (Cl-/SO42-), with a permselectivity of 34.02, which is much higher than the corresponding values of dopamine (DA)modified AEM (i.e., 11.59) and of the pristine AEM (i.e., 1.00). In addition, fouling experiments show that the transition time (the point time in fouling experiment when a voltage dramatically increases; that's to say, foulant dramatically occurs) of the optimum membrane is 112 min, indicating the superior anti-fouling property of SDA modified AEM, compared with pristine AEM (76 min). The facile fabrication process and superior performance of modified AEM suggest that as-prepared is potentially applicable in ED for separation of monovalent and multivalent anions.