Advanced Treatment Of Levofloxacin In Medical Wastewater By Electrocatalytic Oxidation

With the rapid improvement of national industrial level and the overuse of antibiotics,antibiotics would inevitably enter the water environment,which would cause irreversible harm to human beings and the ecological environment.Levofloxacin is one of the most widely used antibiotics in human and animal husbandry.At present,scholars have been able to detect the presence of levofloxacin in pharmaceutical wastewater or pesticide wastewater.In view of the characteristics of antibiotics,it is difficult to achieve efficient degradation of antibiotics by traditional biochemical techniques.Therefore,electrocatalytic oxidation technology was introduced in this paper to achieve efficient and rapid degradation of pollutants.Firstly,titanium suboxide electrode as the anode,ruthenium-titanium electrode as the cathode,both electrodes were employed to degrade the levofloxacin model wastewater,with total organic carbon(TOC)removal rate as the key technical index in this paper.The optimal reaction conditions were obtained by response surface methodology.When the current density was 39.6 A/m~2,the initial pH was 6.5,the flow rate was 50mL/min,the chloride concentration was 4‰,and the reaction time was 120min,the TOC removal could reach 41%,which was basically consistent with the prediction result(40.84%)by response surface methodology.The morphology and properties of the electrode were analyzed by XRD,XPS,AFM,SEM,LSV and CV,which showed that the electrode was stable before and after reaction.Secondly,to further improve the degradation efficiency of levofloxacin,we combined the advantages of single atom and carbon materials to prepare a single atom confined carbon nanotube composite electrode to further improve the degradation efficiency of levofloxacin.We attempted to improve the catalytic activity of the electrode by using a single atom confined carbon nanotube composite electrode.To optimize the preparation conditions,the electrode was prepared by changing the type of single atom and the amount of PTFE(Polytetrafluoroethylene)doping.The electrode was applied to the treatment of levofloxacin wastewater.The results showed that when the PTFE content was 0.15 mL,the conversion of levofloxacin could reach 70%,which was 50%higher than that before the addition of single atom.To improve the stability of the electrode,a layer of ruthenium meta was loaded onto the electrode surface.The stability and catalytic activity of the electrode were investigated by changing the molar ratio of Ruthenium to Titanium.The results showed that the stability of the prepared electrode was the optimal when the ruthenium-titanium ratio was8:2.Then the morphology,properties and the existence state of single atoms of the electrode were analyzed by XRD,XPS,STEM,SEM,LSV,CV and other characterization methods.Finally,the active species and active center in the degradation process of levofloxacin were determined by quenching experiment.