Hydrogen Bonding and Electrostatic Interaction-induced Nanochannels Enabling Fast Monovalent Ion Transport for Efficient Electrodialysis

Abstract

Abstract Efficient and selective ion transport in nature is primarily facilitated by ion-conductive biological channels in cell membranes. These channels reveal an architectural design with specialized functionality. Drawing inspiration from this, our study focused on developing a monovalent ion transport membrane through interchain interactions between polybenzimidazole and sulfonated poly (ether ether ketone) to form angstrom-scale confined nanochannels. The nanochannels exhibit pronounced hydrogen-bonding interactions with hydrated multivalent ions, while rendering significant charge effects that impede their transition by compressing the effective passageways. Both hydrogen bonding and electrostatic interaction synergistically result in high selectivity of monovalent ions over multivalent ions, as the latter necessitates overcoming higher energy barriers compared to the former for transport through the nanochannels. The resulting membrane achieved high monovalent ion permeation rates of 1.35 mol·m−2·h−1 with high mono/multivalent ion selectivity for K+/Mg2+ of 56.5 and K+/Al3+ of 286. Our discoveries provide valuable strategies for developing sub-nanometer nanochannels with desired functionality that contributes to remarkably efficient ion separation via electrodialysis and beyond.