Highly Porous Self-Supporting Graphene Oxide-Based Membranes for the Selective Separation of Lithium Ions

Facilitating the accurate recognition of lithium ions (Li+) by filtration membranes is of great significance for the efficient and selective separation of Li+ from saline lake brine and seawater. Herein, a highly porous self-supporting graphene oxide-based (GCS) membrane modified by single-walled carbon nanotubes (SWCNTs) and 4-aminobenzo-12-crown-4 (AB12C4) was fabricated via a facile and versatile vacuum filtration method. The highly porous structure constructed with polystyrene microspheres as a self-sacrificial template could provide a larger contact area at the solid–liquid interface. Moreover, the addition of electric SWCNTs endows the GCS membrane with a tunable adsorption behavior by an external electric field. Meanwhile, the decoration of AB12C4 on the multilayered GCS membrane realizes a specific recognition of Li+ with an excellent adsorption capacity of 37.0 mg g–1, exhibiting considerably high separation factors against Na+ (18.97), K+ (26.19), Mg2+ (16.67), and Ca2+ (19.64). According to the density functional theory calculations, the adsorption of GCS membrane for Li+ is more thermodynamically favorable than that of the contrast ions. This work demonstrates an effective approach with the convenient vacuum filtration technology for the selective adsorption of Li+, which could alleviate the shortage of lithium resources.