Preparation Of Bismuth Halide Oxide Composite And Its Application In Environmental Field

With the rapid development of economy and industry,environmental pollution has restricted the sustainable development of society and become an urgent problem to be solved in the 21st century.In recent years,semiconductor photocatalysis technology has become an effective way to control environmental pollution.In the industrial application of traditional TiO2 photocatalyst,because of its high band gap(3.2 eV)and narrow absorption spectrum,causing it to respond only to ultraviolet light,and its low utilization of solar energy,which could not meet the industrial requirements.Therefore,it is necessary to develop a photocatalyst with visible light response.BiOX(X=F,Cl,Br,I)as a new type of photocatalyst has been proved to be a promising semiconductor catalyst for the decomposition of various organic pollutants due to its special flake structure and good chemical stability.In bismuth oxyhalide compounds systems,BiOBr and BiOI respond to visible light,while BiOF and BiOCl respond to ultraviolet light.At present,there are many studies on bismuth oxyhalide,mostly researchers tried to compound any two groups of substances in BiOX(X=Cl,Br,I)system to form a new solid solution.But,the photocatalytic activity of this solid solution is still limited to some extent.In this paper,the method of combining solid solution with other semiconductors is used to further improve the photocatalytic activity.In this paper,BBN/Bi0.5O0.5ClxBr0.5-x heterojunction photocatalyst was prepared by one-step hydrothermal method and BiOF/BiOClxBr1-x composite photocatalyst was prepared by ultrasonic-assisted alcoholysis.The effects of different preparation conditions on the properties of composite photocatalysts were systematically studied by means of XRD,SEM,TEM,EDS,Mapping,XPS,UV-vis DRS and other representations.The crystal structure and morphology,microstructure,element distribution and composition,specific surface area and molecular structure of photocatalysts were compared.The specific research results are as follows:(1)BBN/Bi0.5O0.5ClxBr0.5-x heterojunction photocatalyst was prepared by one-step hydrothermal method,and the effects of different preparation conditions on the photocatalytic properties of Bi6O6(OH)3(NO3)3 1.5H2O(BBN)/Bi0.5O0.5ClxBr0.5-x composite photocatalyst were systematically studied by means of XRD,SEM,TEM,EDS,Mapping,XPS and UV-vis DRS and other representations.Through photodegradation experiments of Rhodamine B or phenol as target degradation products,comparing which preparation conditions with the best photocatalytic activity and analyzing the reasons through the mechanism of photodegradation.The results showed that the absorption value of the composite catalyst increased when the BBN catalyst was compounded on the surface of Bio.5O0.5ClxBr0.5-x solid solution,which restrained the recombination of photogenerated electron-hole pairs and improves the photocatalytic performance significantly.In the degradation of rhodamine B(phenol)dye,BBN/BiOCl0.6Br0.4 photocatalyst showed the best photocatalytic performance when x=0.3.When exposed to visible light for 60 minutes,the degradation rate of rhodamine B reached 93.3%,and when exposed to visible light for 120 minutes,the degradation rate of phenol was about 90.5%.Finally,through capture experiments,O2-and H+were considered to be the main active substances in the photocatalytic process in the process of photocatalytic degradation of dyes.(2)BiOF/BiOClxBr1-x composite photocatalyst was prepared by Ultrasonic assisted alcoholysis method,and the effects of different preparation conditions on the photocatalytic properties of BiOF/BiOClxBr1-x composite photocatalyst were systematically studied by means of XRD,SEM,TEM,EDS,Mapping,XPS and UV-vis DRS and other representations.Through photodegradation experiments of Rhodamine B or phenol as target degradation products,comparing which preparation conditions with the best photocatalytic activity and analyzing the reasons through the mechanism of photodegradation.The results showed that the absorption value of the composite catalyst increased when the BF catalyst was compounded on the surface of BiOClxBr1-x solid solution,which restrained the recombination of photogenerated electron-hole pairs and improves the photocatalytic performance significantly.In the degradation of rhodamine B(phenol)dye,BiOF/BiOClxBr1-x photocatalyst showed the best photocatalytic performance when the load is 30%.When exposed to visible light for 45 minutes,the degradation rate of rhodamine B reached 97%,and when exposed to visible light for 120 minutes,the degradation rate of phenol was about 89.5%.Finally,through capture experiments,O2-and H+were considered to be the main active substances in the photocatalytic process in the process of photocatalytic degradation of dyes.