Ag-Nanoparticle-Bearing Poly(vinylidene fluoride) Nanofiber Mats as Janus Filters for Catalysis and Separation

Hydrophilic Ag nanoparticles were pattern-deposited onto one side of an electrospun poly(vinylidene fluoride) (PVDF) nanofiber mat, yielding a Janus filter. The filter was used to separate a receiver cell from a reactor cell that contained an aqueous 4-nitrophenol/NaBH₄ solution. Upon contact with this solution, the Ag nanoparticles catalyzed the reduction of 4-nitrophenol to 4-aminophenol. After the reaction reached completion, ethyl acetate was added into the reactor to extract the product. During this process, the ethyl acetate containing 4-aminophenol also selectively permeated regions of the hydrophobic yet oleophilic PVDF mat that were not covered by Ag nanoparticles. The product was obtained after the evaporation of ethyl acetate. This paper demonstrates the first use of a Janus filter in a catalytic separatory reactor that catalyzes a chemical reaction and then facilitates the eventual separation of the formed product via filtration.