Study On The Degradation Of Levofloxacin By Peroxymonosulfate Activated By Modified Copper-based Catalytic Material

Among modern wastewater treatment technologies,advanced oxidation（AOPs）has been widely studied in recent ten years for its excellent performance in the decomposition of organic matter.In the field of catalysis,the transition metal Cu has excellent physical properties,chemical properties and catalytic activity,and is often used in the field of advanced oxidation.Levofloxacin（LVF）,one of the fluoroquinolones,has the characteristics of long half-life,stable structure,biological toxicity to microorganisms,and is difficult to be degraded in natural water.Therefore,this paper mainly studies the preparation of copper catalyst and the catalytic degradation of LVF by peroxymonosulfate（PMS）,and discusses the performance and mechanism of activating PMS by copper based nanomaterials.The results were as follows:（1）Using polyethylene glycol（PEG）as solvent,the modified Cu O-400 catalytic material was successfully prepared by adding urea to the material synthesis.It was characterized by XRD,FTIR,SEM,XPS,BET,etc.It was proved that Cu O-400 was successfully synthesized with a specific surface area of 9.23 m²/g,which was 25 times larger than the specific surface area of commercially available Cu O.By examining the influence of single factor,it was showed that the optimal reaction condition:at room temperature,when the p H of reaction system was7.5,the amount of PMS was 0.4 g/L,the amount of catalyst was 0.25 g/L,the reaction time was60 min,the removal rate of 100 m L 25 mg/L LVF was up to 85%.The results of XRD,FT-IR and flame atomic absorption spectrophotometry before and after use of Cu O-400showed that the catalyst could still maintain good catalytic activity and the morphology of the catalyst had no change after five cycles,which proved that Cu O-400 had good stability.XPS analysis,free radical quenching test and EPR test It showed that the main active species in the reaction process was OH·by XPS analysis,free radical quenching test and EPR analysis.（2）N-CuFe₂O₄@CNTs nanomaterials were synthesized successfully,and it was characterized by XRD,FTIR,SEM,XPS,BET,etc.The composite of Cu/Fe bimetallic oxide and CNTS not only increased the specific surface area of the catalytic material（from 9.23 m²/g to 38.36 m²/g）,but also further activated the degradation of LVF by PMS.When the p H of the reaction system was 5,the amount of PMS was 0.2 g/L,and the amount of catalyst was 0.2 g/L,the removal rate of LVF reaches 95%.The LVF removal rate of the catalyst was still higher than 70%after five cycles of experiments.The determination of metal leaching by flame atomic absorption showed that N-CuFe₂O₄@CNTs nano has good stability and recyclability.The analysis of free radical quenching and EPR test showed that SO₄^-?was the main active substance in the removal of LVF by N-CuFe₂O₄@CNTs/PMS system.Finally,the analysis of intermediate products revealed that LVF degradation was mainly through defluorination,decarboxylation,dealkylation and deamination under N-CuFe₂O₄@CNTs/PMS system.The feasibility of preparing Cu-based catalyst in the new way was proved.It provided theoretical basis and technical support for the degradation of LVF and other antibiotics.