Electric Field-assisted Or Mo-doped Enhanced Pyrite-based Heterogeneous Fenton Reaction To Remove Organic Pollutants:Performance And Mechanism

Compared with the traditional Fenton system,the pyrite-based heterogeneous Fenton system has attracted extensive attention due to its simple operation,mild reaction conditions,green and high efficiency.However,this technology has problems such as low catalytic activity and slow Fe²⁺and Fe³⁺circulation speed,which limit its widespread application.In this paper,electric field-assisted and multivalent metal Mo-doped methods are used respectively to improve the catalytic efficiency of pyrite-based heterogeneous Fenton system,and also study the performance of the catalytic system,catalytic material properties,removal effect of pollutant.The main research results are as follows:（1）Natural pyrite was used as catalyst to activate H₂O₂ for Rhodamine B（Rh B）degradation.The color-removal rate and TOC removal rate of Rh B by pyrite/H₂O₂,electricity/H₂O₂,and（pyrite+electricity）/H₂O₂ systems were compared.Explore the synergistic effect between the applied electric field and pyrite catalysis.The experimental results show that the electric field assistance can significantly improve the catalytic activity of pyrite.When the H₂O₂ dosage is 10 m M,the applied voltage is 3V,and the flow rate is 50 m L/min,the removal rate of Rh B and TOC can reach 99.76%and 52.11%respectively after 4 h of reaction;Carbon felt modified cathode can improve the removal of pollutants;EPR test results show that the main active substances of the reaction system are singlet oxygen（¹O₂）and hydroxyl radical（·OH）,and the concentration of active species in the（pyrite+electricity）/H₂O₂ system is significantly higher than that in the pyrite/H₂O₂system without applied electric field.（2）Synthesis of Mo doped FeS₂（FeS2@Mo）heterogeneous Fenton catalyst by solvothermal method.The morphology and structure of the samples were characterized by SEM,TEM,XPS and XRD.The effects of the H₂O₂concentration,the dosage of FeS₂@Mo,initial pH value and other conditions on the degradation of BPA were studied.The results showed that Mo doped FeS₂ under the experimental conditions presented petal shaped spheres with a size of 500～1000 nm;Under the condition of 5 m M H₂O₂,100 mg/L FeS₂@Mo pH=3.5,the system has the best degradation effect on pollutants,and the degradation rate of BPA reaches 99.1%in10 minutes;The quenching experiment and EPR detection results show that the main active components in the system are hydroxyl radical（·OH）,singlet oxygen（¹O₂）and superoxide radical(·O^2-),and·OH and ¹O₂ are dominant;By measuring the concentration changes of Fe³⁺and Fe²⁺in the two reaction systems.The doping of Mo helps to increase the ratio of Fe²⁺in the solution and promote the conversion of Fe³⁺to Fe²⁺,thus improving the heterogeneous Fenton catalytic efficiency.The research results show that the catalytic performance of pyrite-based heterogeneous Fenton system can be effectively improved by electric field assisted and metal Mo doping methods.The research results provide an effective way to improve the catalytic performance of heterogeneous Fenton system,and are also conducive to further expanding the application of heterogeneous Fenton system...