The Removal Of Sulfamethazine By Electrochemical Oxidation Method Andproducts Analysis

Sulfamethazine?SMZ?is a sulfa antibiotic that is mainly used as a veterinary drug.It is detected in surface water,groundwater,and soil.SMZ has an inhibitory effect on the growth of environmental microorganisms.Long-term exposure to the environment can increase the risk of drug-resistance genes.Electrochemical oxidation method is an environment-friendly advanced oxidation technology,which has many advantages such as simple operation,no chemical agent,easy automation,no secondary pollution,etc.It has received extensive attention in the field of biodegradable organics.The Ti/PbO₂electrode was used in the experiment.Under the conditions of water distribution in the laboratory,the effects of current density,initial concentration of SMZ,electrode spacing,electrolyte concentration,water-dispersing matrix,and suspended solids on the electrochemical oxidation of SMZ were analyzed by single factor analysis.UPLC-TOF-MS was used to detect the intermediate products during the electrochemical oxidation reaction,and the effect of adding nitrite on electrochemical oxidation product of SMZ was studied.Based on the above research content,we have obtained the following conclusions:.?1?Under current density of 5 mA/cm²,electrolyte concentration of 0.05ol/L,and electrode spacing of 2 cm,the initial concentration of SMZ is 5 mg/L.This is the best condition for this experiment.Under this condition,the energy consumption per unit of magnitude of SMZ removal is the lowest,which is 0.068 kWh/m³.When 5.5?pH?11,the removal of SMZ is not affected by pH;?2?With the secondary effluent from the sewage treatment plant as the matrix,the SMZ removal rate is three times that of the laboratory water distribution matrix in the 60 min reaction.Suspended material can increase the removal rate of SMZ and reduce EE/O;?3?Current density has a greater influence on the removal of SMZ;when the current density is in the range of 5 to 50mA/cm²,EE/O will have a peak energy consumption as the current density increases.When the current density is at both ends,the energy consumption is lower.low;?4?The ions in the water have a great influence on the removal of SMZ,and the order of influence size is Cl^->NO₂^->PO₄^3->Fe²⁺>Fe³⁺>NO₃^-.After adding Cl^-,SMZ can be removed within10 min below the detection limit;?5?Through the detection of electrochemical oxidation of SMZ reaction solution,a total of 12 products were detected.The product is mainly formed by nitration,cleavage of the sulfonamide S-N bond,oxidation of the aniline group and rearrangement of the SMILEs.By comparison with the oxidation product of the nitrite reaction solution,it was found that nitrite had a certain influence on the product formation,and nitrite was a necessary condition for the formation of product T12.The experiment can provide a theoretical reference for the application of electrochemical oxidation to remove SMZ in the actual wastewater.