Preparation Of MoS₂ And CuFe₂O₄-Based Catalysts And Their Performance In Fenton-Like Systems For The Degradation Of Typical Organic Pollutants

Compared with other wastewater treatment technologies,Fenton catalytic technology has the advantages of environmental friendliness,simple equipment and complete mineralization of refractory organic pollutants.However,the limitations of Fe³⁺/Fe²⁺conversion efficiency,low p H applicability,and low H₂O₂ utilization in the Fenton system severely limit the development of Fenton technology.Therefore,in response to the above problems,this topic improved the limitation of the Fe³⁺/Fe²⁺conversion process in homogeneous Fenton like systems by introducing a reducing MoS₂ as a cocatalyst,and also studied the effect of the crystal structure of MoS₂ on the reaction process.Subsequently,in order to achieve the recovery and utilization of the catalyst,a new type of magnetically recoverable 1T/2H-MoS₂/CuFe₂O₄ composite catalyst was prepared by introducing CuFe₂O₄.The efficient degradation of organic pollutants was achieved by activating PMS in a heterogeneous system.The synergistic mechanism of MoS₂ and CuFe₂O₄ in the degradation system was explored,and the effect of phase transition of MoS₂ on the degradation of organic pollutants and the degradation mechanism were studied.The introduction of PMS may lead to the salt exceeding the standard,so a new Ag/CuFe₂O₄-OVs composite catalyst with magnetic recovery was prepared to realize the efficient activation of H₂O₂ and the rapid degradation of organic pollutants,and the reaction mechanism in the catalytic process was put forward.Draw the following conclusions:（1）The successful preparation of MoS₂ was confirmed by SEM and EDX characterization,and it was found that with the increase of preparation temperature,the formation of MoS₂flower balls became more sufficient,while the diameter of flower balls gradually increased.The transformation of MoS₂ phase was characterized by TEM,XRD,and XPS.Compared to 2H-MoS₂,1T-MoS₂ has more abundant active sites and higher conductivity.The increase in preparation temperature leads to an increase in 1T-MoS₂,but excessive temperature directly leads to the formation of 2H-MoS₂.Combining XPS characterization and phenol degradation experiments,it was proved that 1T-MoS_7TD had higher catalytic activity,with the highest content of 1T phase at 180℃,and had the best degradation efficiency.The phenol degradation rate within 20 minutes was 91.14%.In addition,the MoS₂/PMS/Fe³⁺system exhibits excellent degradation performance and cyclic stability for phenol,Rh B,and OFX.After that,active species capture experiments confirmed that the main active species of the catalyst were ¹O₂,SO₄^·-,and^·OH also contributed.Based on this,the degradation mechanism of MoS₂/PMS/Fe³⁺system was proposed.The combination of XPS characterization and changes in the concentration of Fe²⁺in the catalytic system indicates that MoS₂ has a good catalytic performance,indicating that the MoS₂/Fe³⁺/PMS catalytic system achieves an efficient oxidation reduction cycle of Fe²⁺/Fe³⁺and Mo⁴⁺/Mo⁶⁺.（2）Based on（1）,a 1T/2H-MoS₂/CuFe₂O₄ composite catalyst was successfully prepared,which improved the secondary pollution caused by excessive Fe in the system on the basis of magnetic recovery of the material.At the same time,the influence of the phase structure of MoS₂ on the reaction system was analyzed by adjusting the hydrothermal temperature during the material preparation process.Combining XPS characterization and phenol degradation experiments,it was found that MC-200 had the best catalytic performance,with a phenol degradation rate of 95.8%within 20 minutes,and the highest content of 1T phase.This proves that 1T-MoS₂ can effectively promote the cyclic conversion of Fe³⁺/Fe²⁺and Cu²⁺/Cu⁺in the reaction system.Finally,active radical capture experiments and electron spin resonance（ESR）results show that SO₄^·-is the main active substance in the MC-200/PMS system.This study provides a new idea for the application of MoS₂/spinel ferrite/PMS in wastewater treatment.（3）A new type of Ag/CuFe₂O₄-OVs composite catalyst was prepared by tartaric acid reduction method and its degradation performance for phenol in H₂O₂ Fenton system was studied.Oxygen vacancies can significantly enhance the adsorption of H₂O₂on the surface of the defect site,and abundant local electrons can activate the O-O hybrid reaction to generate^·OH.The presence of Ag can greatly enhance the electron transfer and further enhance the catalyst activity.Through XRD characterization,it was found that copper ferrite treated with tartaric acid had a peak of elemental Cu,and the conductivity of the catalyst was measured by electrochemical methods.Electrochemical impedance spectroscopy testing showed that the sample Ag/CuFe₂O₄-OVs had the lowest impedance compared to CuFe₂O₄ and CuFe₂O₄-OVs.Combined with the phenol degradation effect,the importance of electron transfer speed for the reaction was successfully confirmed.In summary,oxygen vacancies can be used as catalytic centers to generate^·OH through a single electron transfer process,while also accelerating electron transfer in the system.In cooperation with Ag,they promote the redox cycle of Fe²⁺/Fe³⁺and Cu⁺/Cu²⁺,achieving high-speed degradation of pollutants in H₂O₂Fenton like systems.