Heterogeneous Fenton Selective Degradation Of Nitrogen-containing Heterocyclic Based On Catalyst Characteristics And Electric Field

Nitrogen-containing heterocyclic are toxic and refractory pollutants widely distributed in the environment.The treatment of wastewater containing these organic matter has problems such as low degradation efficiency and harsh reaction conditions.Heterogeneous Fenton technology,as one of the most promising pollutant treatment technologies,can generate hydroxyl radicals.In particular,low molecular acids,intermediate products of organic compounds,will competitively consume free radicals and affect the reaction efficiency of heterogeneous Fenton.Therefore,regulating the selective attack of free radicals to target pollutants and reducing system interference are the keys to effectively improve the degradation efficiency of heterogeneous Fenton technology.Based on the above goals,functional catalysts were prepared by means of regulation,and pyrazole was selected as the target pollutant.The effect of catalyst properties on the degradation of pyrazole was investigated in a heterogeneous Fenton system.On the basis of interface regulation of the catalyst,an electric field-enhanced heterogeneous Fenton oxidation reaction system was further constructed,and the isolated intermediate low molecular organic acid could be used for subsequent biochemical treatment,which further enhanced the selective degradation of pyrazole.The main conclusions of this study are as follows:（1）Fe/Al₂O₃ catalysts,C/Al₂O₃ catalysts,and Fe-C/Al₂O₃ catalysts were prepared by vacuum induction-high temperature calcination method.Compared with Fe/Al₂O₃ catalyst,the isoelectric point of Fe-C/Al₂O₃ catalyst is lower and the electronegativity of Fe-C/Al₂O₃catalyst is enhanced.Dynamic contact angle analysis showed that the hydrophobicity of Fe-C/Al₂O₃ catalyst was enhanced after carbon doping.The enhancement of electronegativity and hydrophobicity is beneficial to enhance the selective adsorption capacity of the catalyst interface.In addition,the catalyst has excellent stability.The degradation ability of pyrazole decreases slightly by 5%-6%after 8 times of recycling,and only a small amount of metal ions is dissolved.（2）The influencing factors of heterogeneous Fenton degradation of pyrazole and the selective degradation of pyrazole by catalyst characteristics were studied.In the process of heterogeneous Fenton reaction,the selective degradation effect of catalyst characteristics on different organics was explored:When using Fe/Al₂O₃ catalyst,the degradation effect of formic acid is 4%higher than that of Fe-C/Al₂O₃ catalyst.The surface electronegativity of Fe-C/Al₂O₃catalyst is stronger than that of Fe/Al₂O₃ catalyst.Due to electrostatic attraction,the selective degradation ability of weakly basic pyrazoles is increased by about 40%.（3）The selective degradation of pyrazoles by electric field enhanced heterogeneous Fenton was studied.The introduction of electric field into the heterogeneous Fenton system can effectively improve the selective degradation ability of pyrazole.When voltage value is 1.0 V,the treatment effect and the effective utilization rate of·OH both reach the best.From the analysis of TOC degradation,it is known that the mineralization rate of the system is limited,and free radicals selectively degrade pyrazole.The generated low molecular organic acid radicals migrate from the cathode chamber to the anode chamber under the action of electric force.The concentration of acid migrated to anode compartment increased by 4 times at 1.0 V.Therefore,the·OH generated in the cathode compartment can selectively degradation pyrazole,and reduce the competitive consumption of organic acids to free radicals,which further improve the selective degradation ability of the system.