Preparation Of Graphene Doped Ti/SnO₂-Sb Electrode And Study On Degradation Of Fluoroquinolones Wastewater

In recent years,the excessive use and abuse of antibiotics has attracted widespread public attention.Antibiotics are difficult to degrade by conventional biological treatments,resulted in the continuously detected in water environment.The persistence of antibiotics in the water environment has caused serious harm to human health and ecological safety.As one of the typical antibiotics,fluoroquinolones(FQs)are widely used in the treatment of human diseases,animal husbandry and aquaculture which seriously polluted the natural water.Therefore,it has great practical and theoretical significance to explore an efficient and economical treatment technology of FQs antibiotic wastewater.In this study,the Ti/SnO2-Sb electrodes modified by graphene-doped were prepared using the sol-gel method,which were used to electrochemically degrade the norfloxacin(NOR)simulated wastewater.In the preparation process of graphene-doped modified electrode,titanium was selected as the electrode matrix,and the degradation efficiency of NOR antibiotic wastewater and the change of cell voltage during the degradation process were used as reference indicators.The experiment explore and determine the more suitable electrode preparation conditions were:firing temperature 600?,graphene doping ratio 0.04wt.%,10 times of brushing.Scanning electron microscopc(SEM),energy spectrum analysis(EDS),X-ray diffraction(XRD)and other characterization methods were used to analyze the morphology and structure of the graphene-doped modified electrode.The test results shown that the doping of graphene made the electrode have a denser,finer and more uniform surface structure and a crystal structure with a fuller cell and smaller grains.The doping of graphene effectively increased the specific surface area of the electrode and enhanced the conductivity and stability.Cyclic voltammetry(CV),oxygen evolution potential(LSV),enhanced electrode service life test and other methods were used to analyze the electrochemical performance of the electrode before and after graphene doping modification.The results shown that the electrocatalytic activity of the electrode gradually increased with the graphene doping ratio,showing a tendency to increase first and then decrease.After the modification,the oxygen evolution potential of the electrode was increased,and the side reaction of oxygen evolution was not easy to occur,which improved the electrode's removal effect on the target pollutants.The doping of graphene made the electrode coating not easy to be lost during the electrochemical degradation process,the substrate was not easy to be corroded,and the service life of the electrode was effectively improved.In this study,the self-made graphene-doped modified electrode was used to electrochemically degrade NOR antibiotic simulated wastewater.The optimal experimental conditions for NOR degradation were optimized:initial pH was 3,electrolyte concentration was 0.5 mol/L,current density was 30 mA/cm2,and initial NOR concentration was 100 mg/L.The lower the COD concentration of the wastewater,the better the removal of NOR.Under the optimal degradation condition,the electrochemical degradation rate of NOR wastewater could reach 96.3%in 90min.Through active substance inhibition experiments and pH analysis of NOR degradation process,it was concluded that NOR could be removed mainly by the oxidation of OH produced by electrochemical processes.Mass spectrometry(MS)analysis of degradation intermediates indicated that NOR molecules were decompose mainly converted by piperazine ring and defluorination way.This study introduced graphene into the electrochemical system to improve the catalytic performance of the electrode,and explored the best preparation process parameters of the graphene-doped modified electrode,which enriched the types of high-performance electrochemical anode electrodes.The modified electrode was used for electrocatalytic degradation of norfloxacin antibiotic wastewater,and various conditions in the degradation process were analyzed and optimized.The electrochemical degradation mechanism and possible degradation path of NOR were discussed.It provided a certain supplement to the related knowledge of electrochemical advanced oxidation technology for the treatment of norfloxacin wastewater,and enriched the theory and technical support of norfloxacin wastewater treatment.