Ag NPs coated PVDF@TiO2 nanofiber membrane prepared by epitaxial growth on TiO2 inter-layer for 4-NP reduction application

The catalytic membrane plays an increasingly important role in the environmental remedy. In the present study, a novel catalytic membrane was prepared by growing Ag NPs on the porous PVDF@TiO2 nanofiber (NF) based on the epitaxial growth principle. Using the implanted TiO2 NPs as inter-layer, Ag NPs can be tightly coated to the surface of the porous PVDF@TiO2 NF. The obtained NF membrane can withstand the ultrasonic washing treatment of 4 hrs. Afterward, the reduction of 4-nitrophenol (4-NP) through the filtration using Ag coated NF membrane was investigated. The flux of Ag coated NF membrane reaches 580 Lm(-2) h(-1) bar(-1), and the reduction degree is above 96%. The catalytic activity of the Ag coated PVDF NF membrane remains stable during 7 repeated operation recycles, with each one lasting for at least 2 h. Meanwhile, the calculated apparent reaction rate constant is much higher than that reported in the single reaction process. To explore the reason, a new mechanism based on the adsorption-reaction path is proposed to explain their synergistic effect.