Construction of visible light responsive ZnO/N-g-C3N4 composite membranes for antibiotics degradation

Antibiotics in pharmaceutical and aquaculture wastewater is a growing threat to the environment of world, due to the induction of drug-resistant bacteria and the harm to the aquatic organisms. Photocatalytic membrane, which has immobilized photocatalyst on membrane is an effective and environmentally friendly technology for antibiotics degradation. In this study, a novel photocatalytic membrane was prepared by loading ZnO/N-g-C 3 N 4 composite on commercial polymer membrane with glutaraldehyde as a crosslinker through pressure driven filtration. The loading of the photocatalyst over the membranes was validated by Fourier transform infrared spectroscopy, scanning electron microscope and X-ray photoelectron spectroscopy. The photocatalytic properties of ZnO/N-g-C 3 N 4 composite membrane were observed efficient for degradation of tetracycline, ciprofloxacin and ofloxacin in both immersion and filtration model under visible light (λ > 420 nm). Especially, a ZnO/N-g-C 3 N 4 loading amount of 1.12 g/cm 2 and glutaraldehyde concentration of 45% led to the degradation rate of 100% and 80% for tetracycline at 5 mg/L and 10 mg/L, respectively. Low trans-membrane pressure (0.005 MPa) and narrow membrane size (50 kDa) were favorable for antibiotics degradation in filtration model due to long reaction time on membrane surface. Construction and performance of ZnO/N-g-C 3 N 4 composite membrane might provide new strategy for energy saving wastewater treatment.