A novel PVDF hybrid membrane with excellent active–passive integrated antifouling and antibacterial properties based on a PDA guiding effect

Abstract

A novel and versatile active–passive integrated strategy to integrate both antifouling and antibacterial properties into PVDF membranes was developed. PDA microspheres on modified membranes served as primers, and we proposed that a “PDA guiding effect” existed during the modification process. Specifically speaking, it was a guiding reduction effect from the PDA microspheres toward Ag⁺ and a guiding generation effect toward L-cysteine that were separately in favor of the generation of AgNPs and cysteine flowers in cross-sections of the membranes. In addition, the active–passive integrated strategy presented in this research simultaneously includes both an anti-adhesion approach for reducing the initial adsorption of organisms and an anti-bacterial approach for suppressing the activities of attached organisms on the membranes. Conventional filtration experiments clearly demonstrated that the zwitterionic characteristics of L-cysteine made it possible to greatly reduce the initial adhesion of foulants and the deposition of dead bacteria on the membranes. Various bacteria-based experiments proved that AgNPs were effective at preventing the growth, proliferation, and colonization of microorganisms, as well as the accompanying membrane biofouling after long-term operation. Furthermore, self-driven filtration experiments, natural organic matter (NOM) solution filtration experiments, and protein adsorption tests were also carried out to evaluate the practical applications of the modified membranes. In this research, the PDA guiding effect was directed toward inorganic AgNPs and organic L-cysteine. This effect has great possibilities to be extended to other functional materials and to be broadly applied in the construction of diverse functionalized surfaces.