Composite modification of anion exchange membrane by in-situ layer-by-layer assembly to improve antifouling performance

A novel composite modified strategy by in-situ layer-by-layer (LBL) assembly was proposed to improve antifouling performance of anion exchange membrane (AEM) without requiring disassembling the membrane stack. In this approach, the modified layer consisting of (poly (sodium 4-styrene sulfonate) (PSS) and dopamine (DA))/ (polyethylene imine (PEI) and DA) was alternately constructed on the AEM surface via reversal electrodeposition. The in-situ LBL assembly modified layer not only contained more hydrophilic and negatively charged groups, but also contained more covalent bonding structures due to copolymerization between PEI and DA. As a result, the in-situ LBL assembly five layers composite modified membrane stack (Co-5Layer) had the optimal antifouling performance with alkaline stability, and it had no discernible effect on the desalination performance. Meanwhile, the effect of sodium dodecylbenzene sulfonate on the ion transmembrane migration was revealed by in-situ electrochemical impedance spectroscopy tests. This work provided a new idea of overcoming AEM fouling through in-situ surface modification.