Hydrophilic yolk-shell ZIF-8 modified polyamide thin-film nanocomposite membrane with improved permeability and selectivity

Zeolitic imidazolate framework-8 (ZIF-8) crystals with yolk-shell features were successfully synthesized through synergistic etching and surface functionalization method. The obtained yolk-shell ZIF-8 crystals (named as T-ZIF-8) presented excellent hydrophilicity and perfect dispersity in aqueous solution. Then polyamide thin-film nanocomposite (TFN) reverse osmosis (RO) membranes were fabricated by using the functionalized T-ZIF-8 as nanofillers. The obtained TFN RO membrane exhibited an improved surface hydrophilicity, an increased permeability of 1.1 L m(-2) h(-1) bar(-1) (approximately 1.5 times) and a high rejection of 99.8% for NaCl aqueous solution. It has potential to resolve the trade-off problem between permeability and selectivity. Moreover, the obtained TFN RO membrane showed an excellent stability during a 25 h filtration test due to the enhanced compatibility between nanofillers and polyamide, which implied that the developed TFN RO membrane would have a great potential in desalination.