Construction of g/C3N4-ZnO composites with enhanced visible-light photocatalytic activity for degradation of amoxicillin

g/C3N4-ZnO composite catalysts were synthesized through surface hybridization of the delocalized conjugated-. structure of g/C3N4 with the closely contacted surface of ZnO via a successive and simultaneous calcination procedure, and two kinds of photocatalysts, g/C3N4-ZnO1 and g/C3N4-ZnO2, were obtained. Heterojunctions were formed between the two components, which promote the separation of photogenerated carriers efficiently, and then enhanced the degradation of 100mg/L of AMX. The degradation rate of g/C3N4-ZnO1 was 1.54, 11.33, and 2.52-fold that of g/C3N4-ZnO2, g/C3N4, and ZnO, respectively, at a 3.5-h reaction period, with the dosage of 0.3 g/L, and solution pH at 7.0 +/- 0.2. The recycle and reuse ability was excellent and 90.5% of AMX mitigation was achieved in the fifth cycle. For g/C3N4-ZnO1, electrons migrated from the conduction band of g/C3N4 to that of ZnO via the heterojunction. center dot OH and h+ were the main active species for AMX degradation, compared to center dot O2. dominated for g/C3N4. Twelve intermediate products were identified, and two degradation pathways were inferred for g/C3N4-ZnO1 and g/C(3)N(4)ZnO2, respectively. Finally, transformation products without lactam rings were achieved, which lost most of the antibacterial potencies, and the ecotoxicity was also dramatically decreased as indicated by the ECOSAR program.

Automated summary

g/C3N4-ZnO composite catalysts were successfully synthesized through surface hybridization, with excellent photocatalytic performance. The heterojunctions promoted the separation of photogenerated carriers, accelerating the degradation of AMX. The catalyst exhibited good recycle and reuse ability, and the toxicity of transformation products was significantly reduced.