Design of thin-film nanocomposite membranes via synchronizing interfacial coordination and polymerization reactions for organic solvent nanofiltration

Thin-film nanocomposite (TFN) membranes have received immense research interest due to their high permeability and high selectivity in organic solvent nanofiltration (OSN). Herein, TFN membranes were fabricated by synchronizing interfacial coordination and polymerization reactions occurring at an ionic liquid/water interface. The one-pot interfacial reactions led to the simultaneous formation of Fe-MeIm nanofillers and polyamide thin layers with uniform dispersion and good compatibility. The resultant ternary membranes were denoted as Fe-MeIm/PA/PMIA, wherein the Fe-MeIm nanofillers were well-encapsulated in the ultrathin PA selective layer and both of them were located on top of the solvent-resistant PMIA substrate. The morphologies, microstructure, physicochemical properties, and OSN performance of the resultant TFN and traditional TFC membranes were systematically studied and compared. Moreover, the effects of the concentrations and ratios of reagents during the one-pot interfacial reactions were also elucidated. The optimal TFN membrane showed 5 times higher permeance than the TFC membrane without nanofillers while maintaining a high rejection for Congo red/ethanol separation. Moreover, it also showed good stability in various solvents and long-term stability and remarkably improved mechanical properties. This work provides a novel and time-saving fabrication strategy for TFN membranes for OSN application.