N-cyclic cationic group-functionalized cardo poly(arylene ether sulfone)s membranes with ultrahigh selectivity for diffusion dialysis in acid recovery

To produce high-performance and durable membranes used in diffusion dialysis (DD) for acid recovery, poly(arylene ether sulfone)s containing different N-cyclic quaternary ammonium (QA) cations (CardoPES-C 2 -R(Cl - )) were prepared, and the relationships between the N-cyclic QAs and the properties of the corresponding membranes were explored. The CardoPES-C 2 -R(Cl - ) membranes exhibited ultrahigh H + /Fe 2+ selectivity in DD that was higher than that of a commercial DD membrane and other reported DD membranes. Most importantly, both the acid dialysis coefficient (U H+ ) and the H + /Fe 2+ selectivity of the CardoPES-C 2 -R(Cl - ) membranes can be readily adjusted by regulating the chemical structures of functional groups. Interestingly, because of the hydrogen bonds proven by 1 H NMR, the CardoPES-C 2 -Mor(Cl - ) membrane displayed a higher acid permeability coefficient than other N-cyclic QA cation-based membranes with identical ion exchange capacity (IEC) values, but showed lower Cl - conductivity. Additionally, the CardoPES-C 2 -R(Cl - ) membranes exhibited excellent chemical and operational stability after aging testing and consecutive operation.