Anion permselective membranes with chemically-bound carboxylic polymer layer for fast anion separation

Anion permselective membranes (APMs) are required for several sustainable membrane-integrated anion separations technologies such as electrodialysis (ED), diffusion dialysis (DD), and electro-nanofiltration (ENF). However, an existing trade-off between anion permeation and ion-charge permselectivity of the predominant commercial membranes urging researchers to mature facile strategies for fabricating effectual functional APMs. Here, we propose a facile "covalent bonding-triggered self-assembly (CBTS)" approach to fabricate a new class of chemically-bound carboxylic polymer layered APMs (CCAPMs). The resulting CBTS-integrated CCAPMs offer outstanding monovalent anion permeation (JCl−= 5.18 × 10−8 mol cm−2 s−1) and excellent permselectivity for Cl−-/SO42− system (PSO42−Cl−= 7.31), which is 2 × larger than commercial NEOSEPTA ACS permselective membrane (Japan). Moreover, almost 3 × higher limiting current density and excellent desalination performance of the CCAPMs than NEOSEPTA ACS membrane inferring the usefulness of the proposed CBTS strategy to fabricate the membranes for scientific and membrane-integrated industrial processes.