Study On Mechanism Of Electrochemical Oxidation Degradation Of Sulfamethoxazole By Three-Dimensional Boron-Doped Diamond

Sulfonamides are one of the most commonly used antibiotics today and are widely used in water environments and to treat human diseases.Sulfamethoxazole（SMX）,as a typical sulfonamides antibiotic,cannot be effectively removed in water treatment plants,and its content in water environment gradually increases,which pollutes the environment and threatens human health,so it is necessary to degrade sulfamethoxazole.In this paper,a BDD as an anode,Pt as a cathode and Na₂SO₄as an electrolyte are synthesized for the degradation of sulfamethoxazole by an electrochemical oxidation method.The results are as follows:（1）A three-dimensional reticulated diamond was synthesized by microwave plasma chemical vapor deposition（MPCVD）with copper mesh as the substrate and hydrogen（H₂）,methane（CH₄）and boron（B）as the growth gas at 640°C with output power up to 3800 W.（2）HPLC was used to determine the liquid phase detection conditions of sulfamethoxazole,and the linear relationship between the peak area and concentration of the detection method was verified.Five points were selected for linear fitting,10 mg/L,30mg/L,50 mg/L,80 mg/L and 100 mg/L,respectively.R²=0.9992,which verified the feasibility of this detection method.（3）Through the control variable method,according to the four influencing factors of different current intensity,initial solution concentration,solution electrolyte concentration and initial solution p H,it is found that when the current intensity is 30 m A/cm²,The optimum degradation conditions of sulfamethoxazole were 30 mg/L,0.1 mol/L electrolyte concentration and 7 p H of solution.Under these conditions,the removal rate of sulfamethoxazole electrochemical oxidation for 180 min was 90.03%,the energy consumption was 42768 J,and the energy saving was 54%.（4）Through the change of TOC（total organic carbon）and p H value in the solution during the experiment,the degree of mineralization of the solution can be obtained,and the mechanism of the degradation process can be inferred.The active site of sulfamethoxazole was determined by density functional theory（DFT）calculation,and the intermediates were obtained by high performance liquid chromatography.The degradation mechanism of sulfamethoxazole was further analyzed and three possible degradation pathways were proposed.The toxicity of the intermediate during degradation was studied by ecosar toxicity analysis software.After degradation,the solution was reduced solution toxicity.