PES mixed-matrix ultrafiltration membranes incorporating ZIF-8 and poly(ionic liquid) by microemulsion synthetic with flux and antifouling properties

Polyethersulfone (PES) mixed-matrix membranes (MMMs) incorporating a co-nanofiller of ZIF-8 and poly(ionic liquid) were constructed via a facile one-pot microemulsion strategy, aiming to increase the flux and anti-fouling properties of the original PES membranes. First, ZIF-8 nanoparticles were synthetized in the reverse microemulsion using 1-butyl-3-methylimidazolium (BmimOTF) ionic liquid as a surfactant and 1-vinyl-3-ethylimidazolium tetrafluoroborate (VeimBF4) polymerizable ionic liquid as an oil phase. Subsequently, the oil phase VeimBF4 in the reverse microemulsion was polymerized, and a latex containing ZIF-8 nanoparticles and poly(VeimBF4) was formed. Finally, MMMs were constructed by blending the latex with PES via the phase-inversion method. The microstructures of ZIF-8 and the MMMs were characterized by TEM, SEM, FTIR, XRD, and XPS analysis. Results showed that the mean size of ZIF-8 are small (10 ∼ 35 nm). Addition of the poly(VeimBF4) and ZIF-8 nanoparticles increased the pore size and hydrophilicity of MMMs. The maximum water flux was 105 L m−2·h−1·bar−1 and 90% flux recovery were obtained after five cycles of filtration, and little decrease of WCA appeared on all MMMs after the repeated experiment, indicated the good stability of MMMs. Compared with PES ultrafiltration membrane, pure water flux and flux recovery rate of the MMMs increased by 15 and 2.8 times respectively.