Preparation Of TiO₂/MoS₂ Photocatalyst And Cu-fe LDH Photochemical Catalyst And Their Degradation Of Pollutants In Water

The illegal discharge of industrial wastewater has brought about large-scale water pollution,with complex components that are difficult to deal with,which greatly affects people’s lives and health.People need to find efficient,safe,reliable,sustainable and energy-saving chemical technologies.Because of its advantages of low energy consumption,simple operation and no secondary pollution,photocatalysis has attracted more and more attention.The key of photocatalysis technology is photocatalyst.In this paper,on the one hand,based on the energy band theory,the traditional photocatalyst TiO₂ is compounded with high-quality metallic MoS2 to explore its degradation performance and degradation mechanism for pollutants in water;on the other hand,it is based on the current copper and iron redox couples in electron transport.Advantages Cu-Fe LDH materials were prepared,and photocatalytic technology and chemical catalytic technology were coupled for the first time for the degradation of pollutants in water.The traditional TiO₂ has a wide band gap and can only absorb ultraviolet light.At the same time,the effective separation rate of photogenerated electrons and holes is low,and the photocatalytic performance is suppressed.MoS₂ has the advantages of adjustable energy band structure,non-toxicity,etc.Especially the extremely high carrier mobility of metallic MoS₂ can effectively improve the electron lifetime.Therefore,we combined TiO₂ and MoS₂ to improve the photocatalytic performance of TiO₂.In this thesis,CTAB-TiO₂/MoS₂ composite photocatalyst is synthesized by surfactant CTAB-assisted hydrothermal method.CTAB,as a surfactant,plays an important role in enhancing the interfacial recombination of TiO₂ and MoS₂ and increasing the content of metallic MoS₂.The degradation experiment found that the degradation effect of CTAB-TiO₂/MoS₂ is better than that of TiO₂/MoS₂ and TiO₂.XPS,EIS,Raman and Vis-DRS analysis found that the metallic MoS₂ content in the composite material is as high as 69%,which can provide a high-speed electron transmission channel for excited electrons generated by TiO₂ and semiconductor-type MoS₂.Good interface contact improves the efficiency of electron transfer and is conducive to the separation of electrons and holes.The thesis prepared copper-iron hydrotalcite（Cu-Fe LDH）by co-precipitation method.Using XRD and TEM to study the effect of Cu-Fe ratio on the morphology of the catalyst,it was found that the LDH structure can be formed when the ratio is 2:1⁴:1.The catalyst was applied to the photocatalytic degradation experiment of methylene blue（MB）and ammonia nitrogen for the first time.The results showed that the sample with high purity Cu-Fe（3:1）had the best performance:the kinetic constant of MB degradation was It was 7.9 times without catalyst,and the degradation rate of ammonia nitrogen was 99.5%at 1 minute reaction,which was higher than that of 66.6%without catalyst.Using free radical scavengers,it was found that the degradation process was mainly realized by superoxide radicals,and there were both chlorine radicals and a small amount of hydroxyl radicals.Further combined with the results of EIS and XPS,Cu-Fe LDH can realize the continuous regeneration of surface active sites and the efficient separation of electron-hole pairs in the photochemical catalysis process,and it is a catalyst material with great application potential.