Photocatalytic And Photo-fenton Degradation Of Fluoroquinolones In Water By CN-FeNi-P Bi-transition Metal Single Atom Photocatalysts

In recent years,the pollution of antibiotics in environmental water is becoming more serious,which poses a potential threat to human health and ecosystem security.Photocatalysis as a kind of advanced oxidation technology with degradation of organic pollutants has been widely concerned.Compared with other technologies,photocatalysis can effectively utilize solar energy to mineralize pollutants in waterbodies.Metal single atom catalysts（SAC）have become popular materials in the field of environmental catalysis because of their 100%atomic utilization rate and high catalytic activity.The choice of substrate plays an important role in the performance of SAC.For SAC,graphite-like phase carbon nitride（g-C₃N₄）has been proved to be a promising substrate because lots of pyridine nitrogen in the framework can provide coordination sites for metal precursors.In this paper,porous g-C₃N₄（CN）and the transition metal（Fe and Ni）layered double hydroxides（Fe Ni-LDH）were prepared by pre-polymerization method and hydrothermal method,respectively.Then,the N and P co-coordination bi-transition metal single atom catalysts（CN-Fe Ni-P）was obtained by phosphating calcination method using the above-mentioned ones as precursors.The morphology and structural characterizations proved the existence of Fe and Ni single atoms and their coordination structure;The photocatalytic system of enoxacin（ENO）degradation was constructed by using the as-prepared CN-Fe Ni-P as photocatalyst.The ENO experiment results showed that CN-Fe Ni-P could completely remove ENO in water within 40 min under visible light excitation,and the defluorination rate reached to 58%in 60 min.The results of toxicity test showed that the toxicity of ENO was significantly reduced after photocatalytic degradation;The photo-Fenton system of moxifloxacin（MOX）degradation was constructed by using the as-prepared CN-Fe Ni-P as photocatalyst.The MOX experiment results showed that the optimal dosage of Fe Ni-LDH,CN-Fe Ni-P and H₂O₂ were 0.01 g,0.2 g/L and 5 m M,respectively.The photo-Fenton system could completely remove MOX in 20 min.The degradation efficiencies in the different solution p H values,cation and anion have no obvious changes,indicating that the photo-Fenton has a promising application prospect.In actual wastewater application,such as lake,tap water and industrial wastewater,the results showed that the degradation rate of MOX reached to over 98%within 30 min in CN-Fe Ni-P induced photo-Fenton system.