| With wide attention to environmental pollution,especially to water pollution,it is becoming a research hotspot to use emerging photocatalytic technology with energy-saving and environmental protection effects for solve the pollutants in water.In China,the dyes prepared by traditional methods have a wide range of use with scattered production and backward sewage treatment technology.Hence,it is urgent to develop a new sewage treatment technology.Bismuth oxide based composite materials have attracted much attention as a green and environmentally friendly material with photocatalytic degradation.However,Bi2O3has the characteristics of poor structural stability and easy agglomeration,which limits the wide application in the field of photocatalysis.Therefore,it is of great theoretical and practical significance to find a method for preparing a nano-bismuth oxide material with simple synthesis process,low production cost,small size,good monomer dispersion and high product purity.（1）Preparation and photocatalytic performance of SiO2-supported PHEMA-based bismuth oxide nanocomposites.The St（?）ber method was used to synthesize silicon ball carriers with uniform size.The surface of silica ball carrier was treated with 3-aminopropyltrimethoxysilane and2-bromopropionyl bromide as the atom transfer radical polymerization（ATRP）initiator,and polyhydroxyethyl methacrylate（PHEMA）was grafted through ATRP method.Bismuth nitrate was used as bismuth source to form a polymer-metal complex with PHEMA.The strong oxidizing property of sodium borohydride was used to reduce the bismuth ion in the composite material to metallic bismuth,and the metallic bismuth on the surface of the composite material was then oxidized at 450℃in air atmosphere to obtain inorganic-organic metal oxide composite material.Through various measurements,the morphology,element composition,thermal stability and oxidation rate of the bismuth oxide composite were characterized.The photocatalytic activity of the prepared nanocomposites was evaluated by the degradation of Rhodamine B（Rh B）dye under the irradiation of xenon lamps.The results show that the prepared Bi2O3composite material has good thermal stability.The crystal form of bismuth oxide obtained after calcination isβ-type and uniformly covers the surface of SiO2in the form of nanoparticles to greatly improve the dispersibility of bismuth oxide.When the p H value of the solution is 4,the degradation rate of Rh B reaches 80.7%in 3 hours and 97.9%in 4 hours,which is24.2%higher than the degradation efficiency of pure bismuth oxide in 4 hours.By the method,without changing the chemical properties of bismuth oxide,a bismuth oxide composite material with high photocatalytic activity can be obtained by changing the overall structure of the nanocomposite material.（2）Preparation and photocatalytic performance of PHEMA-based bismuth oxide nanocomposites supported on Ti O2.In order to further enhance the photocatalytic activity of the Bi2O3composite material,the SiO2carrier was replaced by Ti O2which has certain photocatalytic performance.Ti O2microspheres were prepared by solvent evaporation method,and anatase Ti O2carrier was obtained after calcination at 400℃.Using3-aminopropyltrimethoxysilane and 2-bromopropionyl bromide as atom transfer radical polymerization initiator（ATRP）,the surface of the Ti O2carrier was treated,and poly hydroxyethyl methacrylate（PHEMA）was grafted by ATRP to form polymer-metal composite of bismuth nitrate and PHEMA.Using the strong oxidizability of sodium borohydride to reduce the bismuth ions in the composite material to metal bismuth,the metal bismuth on the surface of the composite material was oxidized at 450℃in air atmosphere to obtain inorganic-organic metal oxide composite material.The morphology,thermal stability,adsorption and photocatalysis were studied.The results show that compared to SiO2-PHEMA-Bi2O3,the adsorption performance of Ti O2-PHEMA-Bi2O3is improved by 7.9%.After 3 hours of xenon lamp irradiation,the removal rate of Rh B reaches 91.7%,while it is 98.5%for 4hours xenon lamp irradiation.It shows that replacing the carrier with Ti O2does can remarkedly improve the photocatalytic performance of Bi2O3composite material.（3）Preparation and photocatalytic performance of GO-loaded PHEMA-based bismuth oxide nanocomposites.In order to further improve the overall photocatalytic performance and adsorption performance of the composite material.The graphene oxide（GO）with strong adsorption properties was introduced.The single-layer graphene oxide dispersion liquid was mixed with SiO2or Ti O2carrying Bi2O3composite material,and the Bi2O3composite material was supported on GO.Bi2O3composite materials were combined with GO to improve the overall adsorption performance of the material,and the content of GO was 1.5%.The morphology and elemental composition of the product were determined and synthesized by SEM and EDS.TG and UV-Vis diffuse reflectance spectra were used to determine the overall thermal stability and visible light reflectivity of the material,and those were compared with the composite materials before combining with GO.The adsorption capacity and photocatalytic performance were finally studied.The results show that the introduction of GO can greatly increase the adsorption performance of the composite.After the introduction of GO,the adsorption performance of SiO2-PHEMA-Bi2O3and Ti O2-PHEMA-Bi2O3are increased by 15.1%and 7.9%,respectively.After 3 hours of photocatalysis,GO/Ti O2-PHEMA-Bi2O3’s degradation efficiency of Rh B reaches97.6%,and it is 98.3%after 4 hours of photocatalysis with good recycling performance.This indicates that the introduction of GO can significantly improve the photocatalytic performance and adsorption performance of the composite. |
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