Preparation Of BiOI Composite Photocatalytic Material And Research On Its Degradation Performance Of RhB

The environmental problems brought about by the acceleration of industrialization and urbanization have become more and more serious and have received widespread attention from all over the world.Water pollution control,as one of the major issues in environmental governance,is particularly concerned.In recent years,with the continuous development of my country’s textile industry,the discharge of printing and dyeing wastewater is also increasing.Printing and dyeing wastewater has the characteristics of large water volume,high content of organic pollutants,deep color,large alkalinity,and large water quality changes.Difficult industrial wastewater.Among the many dyes,triphenylmethane dyes are widely used due to the advantages of bright color,high fixation rate,and fast dyeing.However,this type of dyes are highly toxic,high in color,and easy to cause cancer.It is a type of dye wastewater that needs to be treated urgently at this stage.In view of this,a variety of water pollution control technologies have emerged.Among them,photocatalytic degradation technology has gradually become a safe,non-toxic,stable and mild degradation reaction condition,strong oxidation and reduction degradation capabilities,environmental friendliness,and high green energy utilization.One of the important directions for the development of sewage treatment technology.In recent years,the new type of bismuth oxyhalide（BiOX,X=Cl,Br and I）ternary semiconductor V–VI–VII materials exhibit excellent photocatalytic activity due to their unique layered structure.Because the monomeric bismuth oxyhalide has disadvantages such as poor stability and low carrier utilization,current research mainly focuses on modifying it to improve stability and utilization of solar energy.This thesis mainly studies the preparation of bismuth oxyiodide-based composite photocatalytic materials and their degradation of specific pollutants.That is,the BiOI photocatalyst that responds to visible light is selected and modified by compounding BiOCl and doped MWCNTs to improve carrier utilization and stability to achieve efficient degradation of organic pollutants.The specific research content includes:（1）BiOI_xCl_1-xmicrosphere photocatalysts with different I/Cl molar ratios were prepared by solvothermal method,and the structure and shape of the synthesized BiOI_xCl_1-xwere analyzed and studied by characterization methods such as SEM,TEM,XRD,PL,Zeta and EIS.Appearance and light absorption performance.Rhodamine B（RhB）,a typical triphenylmethane derivative,was selected as the target organic pollutant,and the effect of BiOI_xCl_1-xwith different structure and morphology and light absorption properties on its degradation performance was studied.The research results show that BiOI_0.3Cl_0.7has the best photocatalytic activity,and the degradation rate of RhB is 5 times that of monomer BiOI.The reason is that when the I/Cl ratio is 3/7,the crystal has good crystallization performance and has a The layer has a nano-microsphere structure,good stability,a band gap of 2.62 eV,and an optimal charge separation ability.At the same time,the kinetics of BiOI_xCl_1-xdegradation of RhB was fitted,and the results conformed to the Langmuir-Hinshelwood model and followed the pseudo-first-order kinetic equation.Through free radical capture experiments,it is found that superoxide radical(·O^2-)and hydroxyl radical（·OH）play a key role in the reaction process.Due to the existence of BiOI_xCl_1-xheterojunction in the composite photocatalyst,BiOI_0.3Cl_0.7has a good band gap energy and a low photo-generated carrier recombination rate,which greatly improves its photocatalytic efficiency.（2）In order to further improve the utilization of photogenerated carriers,a series of BiOI/MWCNTs composite photocatalysts with different doping amounts of MWCNTs were synthesized by solvothermal method,and characterized by SEM,TEM,XRD,PL,UV-Vis DRS,etc.Means to analyze the structure morphology and light absorption properties of the synthesized BiOI/MWCNTs.RhB was selected as the target pollutant,and the effect of BiOI/MWCNTs with different structure and morphology and light absorption properties on the degradation of pollutants was studied.The research results show that 0.15%of BiOI/MWCNTs nanospheres have a large amount of MWCNTs attached to them.The crystallinity is good,the band gap is 1.96 eV,the photo-generated carrier recombination rate is low,the photocatalytic performance is the best,and it is resistant to pollutants.The degradation effect of BiOI is 2 times higher than that of BiOI monomer.Due to the doping of MWCNTs,the BiOI/MWCNTs composite photocatalyst has a low photo-generated carrier recombination rate,which greatly improves its photocatalytic efficiency.The above research results show that the method of using composite BiOCl or doped MWCNTs can change the morphology and light absorption properties of BiOI,and improve its photocatalytic activity.The modified photocatalytic material has a better removal effect on target pollutants in water,indicating It has a wide range of application prospects in sewage treatment.