Photocatalytic elimination of moxifloxacin by two-dimensional graphitic carbon nitride nanosheets: Enhanced activity, degradation mechanism and potential practical application

Residuals of antibacterial drugs (ADs) threaten human health and ecological equilibrium, whereas few efficient treatments have been developed. Using a photocatalyst of two-dimensional (2D) g-C3N4 nanosheets (CNNS) fabricated by the method of ammonium chloride assisted chemical blowing, a high-efficiency photocatalytic treatment was reported to eliminate moxifloxacin (MOX) as a fourth-generation quinolone. The characterization results indicated that the high activity of CNNS originated from its 2D morphology, large specific surface area and high separation efficiency of photogenerated charges. Furthermore, the photocatalyst dosage, MOX con-centration and the pH of solution were optimized. Based on the detection of reactive oxygen species (ROS) and intermediates in the photocatalytic process, the plausible photocatalytic mechanism and the degradation path-ways of MOX were proposed. The toxicity assessment implied that antimicrobial activity of the photocatalytic degradation products were weakened significantly. The synthetic CNNS demonstrated excellent stability and reusability during five cycles. Finally, we carried out photocatalytic degradation experiments in the simulated real scenarios of tap water, lake water and sunlight. This work suggested the CNNS had great potential for purifying ADs-containing wastewater.

Automated summary

This study developed an efficient method using two-dimensional g-C3N4 nanosheets photocatalyst to degrade moxifloxacin, an antibacterial drug. The results showed that the high activity of the photocatalyst was due to its 2D morphology, large specific surface area, and high separation efficiency of photogenerated charges. The optimized conditions and proposed degradation pathways were supported by the detection of reactive oxygen species and intermediates. The toxicity assessment indicated a significant weakening of antimicrobial activity in the photocatalytic degradation products. The synthesized nanosheets demonstrated excellent stability and reusability. Photocatalytic degradation experiments in simulated real scenarios further showed the potential of the nanosheets for purifying ADs-containing wastewater.