Composite PVDF ultrafiltration membrane tailored by sandwich-like GO@UiO-66 nanoparticles for breaking the trade-off between permeability and selectivity

Abstract

Abstract It remains a great challenge to design and prepare polymeric membranes with excellent permeability while maintaining high rejection and better antifouling. However, emerging materials that are capable of minimizing membrane fouling and breaking the trade-off between permeability and selectivity are urgently needed. In this study, by combining UiO-66 with graphene oxide (GO) nanosheets, sandwich-like GO@UiO-66 was assembled using the solvothermal process, which was later blended with the bulk polyvinylidene fluoride (PVDF) membrane to produce nanocomposite membranes (NCMs) via non-solvent induce phase separation method. With the incorporation of only 1.0 w.t% GO@UiO-66 nanocomposites, the water flux of NCM reached 263.3 Lm-2h−1 from 142.8 Lm-2h−1 and BSA rejection ratio improved to 93.0% from 68.0% compared to the original PVDF membrane, respectively. Meanwhile, GO@UiO-66 NCM displayed impressive antifouling features with an 81.8 % water flux recovery ratio (FRR), which is significantly higher than that of pure PVDF membranes (51.4 %). Sandwich-like GO@UiO-66 nanomaterials increase membrane porosity and open the water molecular permeability channel. At the same time, higher-hydrophilic performance of NCM resulted from more hydrophilic functional groups of the GO@UiO-66 exposure and PVDF phase transformation from α-to-β contributed to the formation of a dense hydration layer on the surface of the membrane and Zeta potential on membrane surface decreased, thus improving organic interception and alleviating membrane fouling. Furthermore, NCMs enhance membrane mechanical strength and chemical stability. Overall results suggest that the inclusion of sandwich-like GO@UiO-66 is a competent modification technique that significantly improves membrane performance and has a great potential for practical application.