Composite anti-scaling membrane made of interpenetrating networks of nanofibers for selective separation of lithium

The selective separation and extraction of lithium from salt lakes is compromised by the high salt concentration and the presence of competing ions. In this study, a class of novel cation exchange membranes based on Kevlar aramid nanofibers (KANFs) was designed via interpenetrating networks of poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSMA) and amide reaction of 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (ATTO). Membranes with different PSSMA content were fabricated, and the final membrane denoted as A#PSSMA@KANF-2 achieved a similar to 1.2 mmol g(-1) ion exchange capacity, similar to 28% water content, similar to 4.5% swelling rate and similar to 1.8 Omega cm(2) surface electrical resistance. The thin A#PSSMA@KANF-2 membrane (similar to 8 mu m thickness) also exhibited a high membrane limiting current density of 32.0 mA cm(-2) (in 0.1 M NaCl solution) and an exceptional desalination efficiency (99.9% for NaCl) in electrodialysis. Moreover, compared to some commercial monovalent selectivity cation exchange membranes (CSO and CIMS membranes, which are two commercial monovalent cation selective membranes), the A#PSSMA@KANF-2 membrane was found functional for the separation of Li+/Mg2+ and to have an excellent anti-scaling performance. As the selectivity has potential to be as high or higher as that of commercial membranes, this work provides a promising method to develop membranes with anti-scaling performance for the extraction of lithium from high salt concentrations in salt lakes.

Automated summary

A novel cation exchange membrane based on Kevlar aramid nanofibers was designed for selective separation and extraction of lithium from salt lakes with high salt concentrations. The membrane demonstrated high ion exchange capacity and desalination efficiency, along with excellent anti-scaling performance.