Fabrication of a Ag/CNQDs/g-C3N4-PVDF photocatalytic composite membrane with excellent photocatalytic and self-cleaning properties

A highly efficient visible light-driven photocatalytic membrane composed of Ag/CNQDs/g-C3N4 and PVDF membranes was successfully prepared by vacuum filter crosslinking. This new type of photocatalytic membrane possessed both excellent photocatalytic degradation performance and photocatalytic self-cleaning properties. The Ag/CNQDs/g-C3N4 photocatalyst coating amount of 10 mg had the highest photocatalytic degradation of norfloxacin (NOR), and the quasi-first-order kinetic constant (k) value was 0.0138 min−1. Moreover, the mechanism of the photocatalytic reaction was also discussed. In addition, bovine serum albumin (BSA) as the simulated pollutant was applied to evaluate the self-cleaning property of the Ag/CNQDs/g-C3N4-PVDF composite membrane. After contamination with BSA, the water flux of the composite membrane decreased from 3880 L (m2 h)−1 to 800 L (m2 h)−1. Then, the maximum pure water flux of the Ag/CNQDs/g-C3N4-PVDF photocatalytic composite membrane recovered 87% (3360 L (m2 h)−1) within 90 min of visible light irradiation, indicating that the Ag/CNQDs/g-C3N4-PVDF photocatalytic composite membrane had excellent self-cleaning properties.