The Research On The Removal Of Sulfamethoxazole From Water Via The Activation Of Persulfate With Graphitized Biochar

Antibiotic is a great discovery and play a very important role in human life.However,in recent years,the heavy use and even abuse of antibiotics have caused them to enter the water environment through various channels,causing pollution.Sulfamethoxazole（SMX）,one of the most used sulfonamide antibiotics,has been frequently detected in water bodies,threatening human health.Among the many methods for removing organic pollutants,the persulfate-based advanced oxidation process（PS-AOPs）have the characteristics of faster rate,higher efficiency,and complete degradation than other methods,which has become the focus of current research.Biochar（BC）material has similar structure and properties to other carbon materials that can activate PS.Due to its wide source and low cost,BC has become a promising PS catalyst.However,there are many kinds of BC,and not all of them have strong catalytic capabilities,so it is of great significance to find efficient and convenient modification methods to improve their catalytic performance.In this study,we used common waste biomass,wood chips as raw materials and ammonium ferric citrate（AFC）as a modifier to prepare a new type of green and efficient graphitized biochar material（WGBC）,and used it to activate PS towards the removal of SMX in water.Through a series of methods such as BET,XRD,XPS,Raman spectroscopy and SEM-elements mapping,WGBC was characterized and analyzed,and it was found that the modification of AFC can make biochar have a larger pore structure,a higher degree of graphitization and more abundant C=O functional group.The removal experiments of SMX showed that the original BC had little ability to remove SMX,while WGBC showed excellent removal performance for SMX.When the concentration of WGBC is 0.1 g/L,the concentration of PS is 0.1 m M,the concentration of SMX is 10 mg/L,and the initial p H value of the solution is less than11,the WGBC/PS system can remove 99%of SMX in water within 120 min.Free radical quenching experiments and electron paramagnetic resonance（EPR）tests proved that·OH,SO₄^·-,¹O₂and O₂^·-all played roles in the degradation of SMX,of which ¹O₂ and O₂^·-played major roles.Using the method of electrochemical measurement,it was concluded that there was a non-free radical oxidation pathway in the degradation process of SMX,in which PS and WGBC combined to form a metastable complex,and WGBC worked as an electron transfer bridge to make SMX directly transfer electrons to PS to cause SMX degradation.In addition,the WGBC/PS system showed strong anti-interference ability to Cl^-,H₂PO₄^-、NO₃^-and humic acid（HA）,and maintained an efficient removal rate of SMX in the presence of these substances.Combined with various characterization methods and analysis of SMX removal experiments,it was shown that the graphitic carbon structure and C=O group may be the key to the efficient catalytic ability of WGBC for PS.This research not only proposes an efficient removal method for SMX in water,but also provides new ideas for the resource utilization of waste biomass and the design of green and efficient PS catalyst.