Degradation Of Sulfa Antibiotics Based On FeS₂ Three-dimensional Electrode System

With the development of the medical industry,the use of antibiotics is becoming more frequent.The sustained use results in antibiotics always being detected in the water,creating the illusion of continuous pollution.These antibiotics are harmful to humans and the natural environment,so the degradation of this emerging organic pollutant has become a hot topic for scholars.At present,electro-Fenton technology has good prospects in wastewater treatment based on its strong oxidizing ability,high efficiency and cleanliness.However,the traditional electric Fenton system has problems such as low H₂O₂ yield.The cathode plate is a major factor restricting the H₂O₂ yield.Therefore,the modification of the cathode plate has become a research hotspot.In this paper,graphite felt with porous structure is used as a carrier.The graphite felt is copper-supported by electrodeposition and combined with Fenton catalyst FeS2 to establish an electro-Fenton-FeS₂（EF-FeS₂）system for sulfamethazine（SMZ）.To degrade,investigate the influence of various factors on the degradation of SMZ,and explore the degradation path of SMZ.The specific research content is as follows:（1）The GF/Cu electrode was prepared by electrodeposition of copper on the surface of graphite felt.It was characterized by XRD,SEM,XPS and CV,The results showed that the modified GF/Cu electrode had a stronger current response and was more likely to produce H₂O₂ by ORR.In the test of the stability of the polar plate,it was found that the GF/Cu plate still maintained high degradation efficiency after five cycles.The EF-FeS₂ system was used to degrade the three antibiotics in a mixed solution.The degradation efficiency of the three antibiotics reached 70% after 2 hours,indicating that the EF-FeS₂ system has good adaptability to different water qualities.（2）FeS₂ is prepared by solvothermal method and ball milling method.Explore the effects of reaction voltage,FeS₂ dosage,initial p H and aeration mode on the degradation of SMZ in the EF-FeS₂ three-dimensional electrode system.The surface response method is used to fit the experimental data,and the model is established for optimization The stability of the three cycles of FeS₂ was investigated,and it was found that direct recycling of FeS₂ for recycling could not achieve good results.However,FeS₂,which was vacuum-dried after washing with dilute acid and pure water,restored its catalytic activity.Material analysis shows that Fe₃O₄,Fe₂O₃,etc.are formed on the surface of FeS₂ after the reaction,forming a passivation layer,which prevents the release of Fe²⁺,and also blocks the interface contact between FeS₂ and H₂O₂,which reduces the catalytic activity of the system for H₂O₂..（3）The quenching experiments were carried out with methanol and t-Butanol,the results showed that·OH was dominant in the reaction process.At the same time,HPLC and LC-MS were used to qualitatively analyze the intermediate products in the process of SMZ degradation.Five main intermediate products were obtained by LC-MS,including p-hydroxybenzenesulfonic acid,2-amino-4,6-dimethylpyrimidine,4-amino-N-carbamimidoyl-benzenesulfanamide,4-hydroxyl-N-carbamimidoyl-benzenesulfanamide,hydroxylated sulfamethazine,and the degradation path of SMZ was inferred.