Boosting photocatalytic degradation of antibiotic wastewater by synergy effect of heterojunction and phosphorus doping.

Phosphorus-doped g-C3N4/ZnIn2S4 (PCN/ZIS) heterojunction photocatalysts were constructed by solvothermal method. The physical and chemical properties were investigated with X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), etc. The degradation of antibiotic wastewater was used to investigate the photocatalytic activities of composites under visible-light irradiation. The 10% PCN/ZIS had the best photocatalytic degradation performance for tetracycline with a photodegradation rate of 0.0874 min-1, which is respectively about 2.9 and 52.0 times than that of pure ZIS and PCN. Meanwhile, it was concluded that the holes and ⋅O2- (superoxide radicals) play dominant roles in the photocatalytic reactions through radicals trapping experiments, while ⋅OH (hydroxyl radicals) has a negative effect. In addition, 10%PCN/ZIS, with excellent stability and recyclability, also exhibited high photocatalytic activity for terramycin, chlortetracycline and ofloxacin. Overall, with the enhanced photocatalytic performance, PCN/ZIS could be potentially applied for photocatalytic degradation of antibiotic wastewater.