Anti-biofouling property and anti-leaching investigation of modifier for PVDF ultrafiltration membrane by incorporating antibacterial graphene oxide derivatives

To improve the anti-biofouling property of polyvinylidene fluoride (PVDF) membrane, three kinds of antibacterial graphene oxide (GO) derivatives were prepared, including imidazole-functionalized GO (Im-GO) and quaternized GO (Q-GO) synthesized by chemical grafting method, and GO loaded with silver nanoparticles (GO-Ag) synthesized by in-site reduction method. The structural characteristics and antibacterial abilities of three kinds of GO derivatives were characterized and investigated. It was demonstrated that GO could be used as a good carrier to prepare the anti-biofouling modifiers. Correspondingly, Im-GO/PVDF, Q-GO/PVDF, and GO-Ag/PVDF ultrafiltration membranes were fabricated using the phase inversion method. In contrast with the blank PVDF membrane, all the GO derivatives/PVDF membranes showed greatly improved permeability and anti-biofouling property. Significantly, the inhibition zone test and fluorescence staining experiment were carried out to investigate the differences between Im-GO, Q-GO, and GO-Ag in the antibacterial mechanisms. The corresponding results suggest that the imidazole and quaternary ammonium salt groups grafted on Im-GO and Q-GO possess great anti-leaching characteristics, while the loss of Ag+ from GO-Ag is relatively obvious. Therefore, Im-GO and Q-GO synthesized by chemical grafting method have greater potential as the anti-biofouling membrane modifiers, considering the accumulation of harmful ions in water and possible reduction in antibacterial stability for GO-Ag.