Search

Tight ultra-filtration (TUF) membranes were constructed by in situ growing zinc imidazole frameworks micro-crystalline leaves (ZIF-L) in polyethylene imine (PEI) and polydopamine (PDA) deposit layers on porous polyethylene (PE) substrates. The effects of preparation conditions on the surface physical and chemical structures as well as on the dye/salt separation performance of the formed TUF membranes were systematically investigated. By inserting selective water permeation channels and increasing contacting surface areas, in situ-grown ZIF-L arrays tightly cross-linked in the coating matrix greatly increased water permeation without trading off dye/salt retention selectivity. The morphology of the included ZIF-L particles could be varied by adjusting the ligand/Zn molar ratio (α) in the preparation processes. Optimized PDA-PEI/ZIF-L@PE TUF membranes containing ZIF-L of cross-cross block morphology showed very high pure water permeability of 180 ± 20 L·m−2·h−1·bar−1 (LMHB) and retention selectivity (S CR/Na2SO4 and S MB/Na2SO4) of 267 and 43, respectively, as well as excellent stability and anti-fouling properties. [Display omitted] • Lower cost-based TUF membranes were prepared for effective dye/salt separation. • In situ-grown ZIF-L increased water flux without losing dye retention selectivity. • PEI and PDA coating greatly enhanced the stability of ZIF-L in water. • Morphology of ZIF-L was tuned for improving membrane performance. • Protonation of the -NH- groups increased positive charge and water flux. [ABSTRACT FROM AUTHOR]