Nature-mimicking fabrication of antifouling photocatalytic membrane based on Ti/BiOI and polydopamine for synergistically enhanced photocatalytic degradation of tetracycline

Fabrication of silver vanadate quantum dots/reduced graphene oxide/graphitic carbon nitride Z-scheme heterostructure modified polyvinylidene fluoride self-cleaning membrane for enhancing photocatalysis and mechanism insight

The enhancement of the self-cleaning ability of photocatalytic membranes and their degradation efficiency over tetracycline (TC) still remains a challenge. In this study, an alternative silver vanadate quantum dots (AgVO₃ QDs) doped reduced graphene oxide (RGO) and graphitic carbon nitride (C₃N₄) nanocomposites modified polyvinylidene fluoride (PVDF) membrane (AgVO₃/RGO/C₃N₄-PVDF) was successfully fabricated to enhance the photocatalytic activity. The AgVO₃/RGO/C₃N₄ nanocomposites were functioned as the active component for the photocatalytic membrane. The unique Z-scheme heterostructure of AgVO₃/RGO/C₃N₄ and the porous PVDF framework synergistically enhanced the separation and transport efficiency of photogenerated carriers and facilitated the interaction between the photocatalyst and the pollutant. As a result, the degradation efficiency of TC for the AgVO₃/RGO/C₃N₄-PVDF reached 88.53% within 120 min, which was higher than those of the binary component membranes (64.8% for RGO/C₃N₄-PVDF and 79.18% AgVO₃/C₃N₄-PVDF). In addition, AgVO₃/RGO/C₃N₄-PVDF exhibited high permeability (1977 L·m^-2·h^-1·bar^-1) and excellent antifouling activity. Under visible-light irradiation, the flux recovery rate (FRR) increased from 92.4% to 99.1%. Furthermore, AgVO₃/RGO/C₃N₄-PVDF could reject 97.4% of Escherichia coli (E. coli) owning to its self-cleaning capacity, and eliminated the E. coli under visible-light irradiation trough the photogeneration of h⁺. This study highlights a highly efficient photocatalytic membrane based on a Z-scheme heterostructure, which may have a great potential application in practical wastewater treatment.