An isoporous ion exchange membrane for selective Na+ transport

作者：Zhu, Qing; Liu, Yahua; Zuo, Peipei; Dong, Yu; Yang, Zhengjin^*; Xu, Tongwen^*

来源：Journal of Membranes Science, 2022, 659: 120805.

DOI：10.1016/j.memsci.2022.120805

• Sodium channel
• Selectivity
• Confined transport
• Ion selective membrane

Biological sodium channels have selectivity filters with extraordinary Na+ selectivity. Realizing this function in ion exchange membranes is highly desirable for technologies related to water, energy, and the environment, but it remains a challenge. Here we report a sodium selective isoporous membrane (NaSIM) derived from lyotropic liquid crystals. This membrane consists of uniform ion conductive channels lined with carboxylate groups. These negatively charged ion channels demonstrate charge-governed ion transport, pH responsiveness, and Na(+ )selectivity. The Na+ selectivity was 1.88 against K+ as revealed from single ion permeation experiment and approached 2.10 in binary salt solutions. The prominent Na+ selectivity may arise from specific interactions between Na+ ions and the carboxylate groups inside the channels, which regulate the energy barriers for monovalent cation transfer. The NaSIM we developed may promote high-precision separation and provides a cornerstone for designing a new generation of ion selective membranes.