Formation of morphologically confined nanospaces via self-assembly of graphene and nanospheres for selective separation of lithium

Selective separation of lithium ions is crucial to recycle lithium from saline lakes. Here, a novel multilayer framework membrane was constructed based on graphene oxide and sulfonated amino-polystyrene nanospheres (rGO@SAPS) via amide condensation reaction and self-assembly. With the large specific surface area of these nanospheres and the anchored multitudinous sulfonate groups and amino groups, the synthesized rGO@SAPS formed unique membranes with morphologically confined nanospaces, and are applicable for the selective separation of Li+ under an electric field. It was estimated that in an electrodialysis system (solution velocity 250 mL min(-1), current density 12.73 mA cm(-2) and membrane thickness 10 mu m), the selective separation efficiency parameter (retention or separation parameter between two different ions) of Mg2+/Li+ and K+/Li+ of rGO@SAPS-2 in 20 min is 46.13% and 9.90%, respectively.