Robust functionalization of underwater superoleophobic PVDF-HFP tubular nanofiber membranes and applications for continuous dye degradation and oil/water separation

In this study, a novel and multifunctional polyvinylidene fluoride-co-hexafluoropropyle (PVDF-HFP)/catechol-polyethyleneimine (CA-PEI)/Ag/3-glycidyloxy propyltrimethoxysilane (KH560) tubular nanofiber membrane (TNM) for applications in dye degradation and oil/water separation was fabricated. Firstly, the PVDF-HFP tubular nanofiber membranes were modified by using a mussel-inspired method. Then, Ag nanoparticles were assembled on the nanofiber surface to improve their excellent catalytic capacity for Methylene blue (MB) and Congo red (CR). Finally, the hydrophilic KH560 was grafted on nanofiber surface and the effects of KH560 concentration on the membrane performance were investigated. The results showed that when the KH560 concentration was 3 wt%, the modified membranes possessed a higher hydrophilicity and permeability. Meanwhile, it could also effectively separate various oil-in-water emulsions with high separation rate and separation efficiency at 0.02 MPa. Moreover, the catalytic and oil/water separation performances had no discernible decay after ten cycle tests, which promoted the potential application of modified PVDF-HFP TNMs for the treatment of practical oily wastewater.