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+/Fe2+ 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 (UH+) and the H+/Fe2+ 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 H-1 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.

Automated summary

By adjusting the chemical structures of functional groups, the properties of CardoPES-C-2-R(Cl-) membranes can be readily adjusted, and these membranes exhibit ultrahigh selectivity and stability in DD.