Dominant Mechanism of Nanofiltration for Chloride/Sulfate Ion Separation in High Salinity Solutions: The Quantification of Pore Size-Influenced Dielectric Exclusion

selective separation with a pore radius at 0.35-0.44 nm (molecular weight cutoff at 180-300 Da). Consequently, we proposed that tailored design of nanofiltration membranes with a precise pore radius to fully utilize the steric and dielectric exclusion instead of increasing membrane charge density is more crucial for monovalent/multivalent ion selective separation in high salinity solutions. Overall, our study reveals the importance of dielectric exclusion and provides new insights into nanofiltration membrane customization and application for ion selective separation in high salinity solutions.