Study On Electrocatalytic Oxidation Degradation Of Antipyrine With Two-dimensional And Three-dimensional Electrodes

Pharmacologically Active Compounds（PhACs）as a class of emerging organic pollutants have been detected in natural water environment around the world.Due to their strong toxicity,widespread existence,and easy bioaccumulation characteristics,they have attracted widespread attention.Wastewater treatment plant effluent is recognized as one of the important sources of PhACs in the natural water environment.The reason is that the traditional sewage treatment process has a poor removal effect on PhACs.Therefore,exploring technical methods that can further effectively remove PhACs from wastewater treatment plant effluent has become a hot topic in this field.Electrocatalytic oxidation technology is regarded as"environmentally friendly"technology because of its advantages such as simple operation,mild process conditions,and no secondary pollution.It has attracted much attention in the treatment of PhACs.However,due to the wide variety of PhACs,the electrocatalytic oxidation technology has limited research on the treatment of PhACs.Therefore,more researches on the treatment of different PhACs by this technology are needed.This study antipyrine as a target the pollutant,examines the two-dimensional electrodes electrocatalytic oxidation degradation antipyrine effect and factors affecting the removal efficiency,in order to improve the removal efficiency of antipyrine,further choose three-dimensional electrodes electrocatalytic oxidation degradation antipyrine,and the third poleγ-Al₂O₃particles were modified,and finally realize the efficient removal of antipyrine,at the same time,the degradation mechanism and possible degradation pathway were discussed,and the specific conclusions were as follows:（1）In the study of two-dimensional electrodes electrocatalytic oxidation degradation of antipyrine with Ti/SnO₂-Ta₂O₅-IrO₂mesh and Ti mesh as anode and cathode respectively,it was found that the current density,electrode distance and initial concentration of antipyrine all affect its removal effect.With the increase of current density（0.2-4 mA/cm²）,the removal efficiency of antipyrine increased（17.4%-50.7%）,but at the same time the energy consumption increased（0.17-2.51 kWh/g antipyrine）,considering the removal efficiency and energy consumption,a current density of 0.5 mA/cm²was more appropriate;as the electrode distance increased（1,2,3 cm）,the removal efficiency of antipyrine decreased（44.5%,35.8%,31.9%）,this was because as the electrode distance increased,the resistance of the solution increased,and the mass transfer coefficient decreased;with the increase of the initial concentration of antipyrine（2,5,10 mg/L）,the removal efficiency and the apparent rate constant of the electrochemical reaction increased first and then decreased.The removal efficiency of 5 mg/L antipyrine was higher（48.4%）.（2）In order to further improve the removal efficiency of antipyrine,the three-dimensional electrodes electrocatalytic oxidation method was used to treat it.Sinceγ-Al₂O₃as particle electrodes has limited improvement in the degradation effect,this part selected the impregnation method to treatγ-Al₂O₃.The particles were modified by Sn-Sb-Bi three-metal loading,and the response surface analysis method was used to design experiments to optimize the concentration of each metal ion in the impregnation solution,and finally get the best concentration ratio:0.5 mol/L Sn Cl₄·5H₂O+0.05 mol/L Sb Cl₃+0.5mol/L Bi Cl₃.When the Sn-Sb-Bi/γ-Al₂O₃prepared with this ratio was used the particle electrodes,the initial concentration of antipyrine was 10 mg/L,the current density was 0.5mA/cm²,the electrode distance was 2 cm,the particle electrode dosage was 10 g,and under the treatment time of 180 min,the removal efficiency of antipyrine by the three-dimensional electrodes electrocatalytic oxidation degradation reached 84.83%.（3）When the initial concentration of antipyrine was 10 mg/L,the current density was0.5 mA/cm²,the electrode distance was 2 cm,the particle electrode dosage was 10 g,and the treatment time was 240 min,the degradation of antipyrine by two-dimensional electrodes,γ-Al₂O₃three-dimensional electrodes and Sn-Sb-Bi/γ-Al₂O₃three-dimensional electrodes were compared,the removal efficiencies of antipyrine for the three were:48.0%,78.3%and94.4%,energy consumption respectively:0.36,0.24 and 0.18 kWh/g antipyrine.It can be seen that the three-dimensional electrodes electrocatalytic oxidation with Sn-Sb-Bi/γ-Al₂O₃as the particle electrodes had a good effect on the removal of antipyrine,and energy consumption relatively low.In addition,the generation of·OH in the electrocatalytic oxidation process of the two-dimensional electrodes and the Sn-Sb-Bi/γ-Al₂O₃three-dimensional electrodes were investigated by the terephthalic acid fluorescent probe method.The results showed that the latter under the same conditions contained·OH,the amount of production of was significantly higher than the former,indicating that the indirect oxidation capacity of the latter was significantly improved.Finally,LC-MS was used to detect the degradation products of antipyrine in the electrocatalytic oxidation process of the three-dimensional electrodes,it was clear that there were three products of N’-acetyl-N’-methyl-2-oxy-N-phenylacetohydrazide,1-acetyl-1-methyl-2-phenyl-hydrazide and aniline,and the possible degradation pathways were speculated.