Precision ion separation via self-assembled channels
Shanshan Hong, Maria Di Vincenzo, Alberto Tiraferri, Erica Bertozzi, Radosław Górecki, Bambar Davaasuren, Xiang Li, Suzana P. Nunes
Abstract
Abstract Selective nanofiltration membranes with accurate molecular sieving offer a solution to recover rare metals and other valuable elements from brines. However, the development of membranes with precise sub-nanometer pores is challenging. Here, we report a scalable approach for membrane fabrication in which functionalized macrocycles are seamlessly oriented via supramolecular interactions during the interfacial polycondensation on a polyacrylonitrile support layer. The rational incorporation of macrocycles enables the formation of nanofilms with self-assembled channels holding precise molecular sieving capabilities and a threshold of 6.6 ångström, which corresponds to the macrocycle cavity size. The resulting membranes provide a 100-fold increase in selectivity for Li + /Mg 2+ separation, outperforming commercially available and state-of-the-art nanocomposite membranes for lithium recovery. Their performance is further assessed in high-recovery tests under realistic nanofiltration conditions using simulated brines or concentrated seawater with various Li + levels and demonstrates their remarkable potential in ion separation and Li + recovery applications.