The Application Of Photocatalysis And Fenton Reaction Synergy System In Environmental Purification

Nowadays,With the development of economy and the improvement of science and technology,the environmental problems are getting more and more serious and have drawn people’s widespread concern.In the traditional methods of sewage treatment and air purification,due to the characteristics of safety,simplicity and cleanliness,Advanced Oxidation Processes（AOTs）Degradation of refractory pollutants has become a hot research topic at home and abroad,Among them,photocatalytic technology has attracted a lot of attentions due to its advantages of mild reaction conditions,low energy consumption,less secondary pollution and Fenton reaction which can degrade refractory pollutants.However,single-point treatment of pollutants faces the problems of high processing cost and incomplete degradation.Therefore,in order to avoid these drawbacks,a variety of AOTs combined technology has attracted the attention of researchers.Photocatalyst and Fenton oxidation combined with their synergetic effect can greatly improve the mineralization efficiency of pollutants in wastewater or waste,so as a new composite oxidation technology plays an important role in the treatment of environmental problems.The photocatalyst combined with Fenton reaction has higher oxidation and mineralization performance than single technology,which can greatly accelerate the reaction rate and efficiency,reduce the use of oxidant,reduce the cost and widen the reaction PH range.The synergetic effect is mainly reflected in two aspects:（1）The electrons generated by photocatalysis promote the reduction of Fe3+,increase the concentration of Fe2+,and promote the progress of Fenton reaction.（2）The reaction of H2O2 with photoelectrons in Fenton reaction reduces the electron-hole recombination rate and enhances the photocatalytic degradation efficiency.Due to the synergistic effect,the degradation efficiency of contaminants is greatly increased.Therefore,the main contents are as follows:1.Preparation of MoS₂@CuS photocatalyst and its synergistic effect with Fenton reagent to purify sewageWrapped MoS₂@CuS composite photocatalyst was successfully prepared by microwave assisted synthesis.Flake-shaped Mo S2 nanosheets wrapped in tubular CuS surface,its unique structure,on the one hand increased the absorption of light on the catalyst,on the other hand,this package structure to some extent inhibited the Cu ions in the catalyst during the reaction Of the loss,improve the stability of the material.This chapter also proves that the degradation of Rhb by composite system is not only a simple addition of Fenton reagent oxidation and photocatalytic oxidation,but also a photocatalytic,separate Fenton reaction and composite system of photocatalytic and Fenton reaction.Synergy.Finally,the synergistic mechanism between photocatalytic and Fenton-like reaction is proposed.It is proposed that the activity of the composite system is improved to a great extent due to the simultaneous mass production of·OH and·O2-in the system,and the synergistic mechanism of the composite system is further proved through the comparison of the activity under different atmospheres.2.Preparation of Fe@C3N4-OH Photocatalyst and Oxidation of NO by Solid-gas Fenton ReactionThe preparation of Fe-deposited C3N4 with hydroxyl group firstly proposed the principle of solid-gas-phase Fenton reaction for NO oxidation and the oxidation of NO with Fe（OH）The experiment proved that the presence of H2O in the NO oxidation system provides the necessary hydroxyl groups for the reaction.When the hydroxyl consumed in the reaction equilibrates with the produced hydroxyl,the NO degradation activity is balanced and the stability of the solid-phase Fenton reaction is solved problem.Finally,the principle of solid-phase Fenton oxidation of NO was proposed and proved.3.Preparation of FeOOH DQ/Mesoporous C3N4 Photocatalyst and Degradation of Water Pollutants by Synergistic Effect between Photocatalysis and Surface Fenton Reaction.This section prepared FeOOH DQ/Mesoporous C3N4 composite photocatalyst,the use of mesoporous C3N4 oxygen group through the C-O-Fe bond in the form of FeOOH DQ in close contact with the C3N4 surface.Through the interaction between FeOOH DQ/Mesoporous C3N4 composite catalyst and HA,the synergistic system of photocatalytic and surface Fenton reaction was proposed for the first time,and its synergistic effect was used to stably and efficiently degrade water pollutants.The combination of photocatalysis and surface Fenton reaction not only improves the degradation activity,but also solves the biggest problem of heterogeneous Fenton system:the loss of Fe ions.In the surface Fenton reaction,the conversion between Fe ions only occurs on the surface of the material,thereby solving the problem of loss of Fe ions in the reaction and improving the stability of the material.The synergistic mechanism of photocatalytic and surface Fenton reaction was also proved by experiments.