Research On Synthesis Of Photocatalysts Modifying Titanium Dioxide Coated Expanded Perlite And The Degration Of Pollutant

With the development of industrialization,wastewater containing organic pollutants and heavy metals was discharged into water,causing serious pollution to the environment.Photocatalytic technology is a promising technology of environmental pollutant treatment,which can eliminate the pollutants completely with a low energy cost.TiO2 is widely used for its strong oxidation ability,stable chemical properties,harmless to human body and low cost.And expanded perlite is often used as carrier because of its honeycomb structure,easy adhesion and low price.In this study,titanium dioxide was loaded on expanded perlite,and then a new type of environmental remediation material was prepared by means of modification.In this paper,photocatalytic materials were prepared by sol-gel method through non-metallic atoms、metal ions、semiconductors doped TiO2 loaded on expanded perlite respectively.Physicochemical properties were analyzed by means of characterization,taking Rhodamine B and hexavalent chromium as target pollutants,and the effect of different materials on pollutant treatment was studied.Then the optimum technological conditions were explored.The main research content and results are as follows:(1)Photocatalysts which is doped with B、N and TiO2 loaded on expanded perlite is prepared.These materials were characterized by X-ray diffraction(XRD),Brunauer-Emmett-Teller(BET),and X-ray photoelectron spectroscopy(XPS).The treatment effects of Cr and Rhb were studied.The results showed that the anatase B-N-TiO2/EP(the mole ratio of boron and titanium is 0.21)obtained macro-mesoporous.and the obtained macro-mesoporous is endowed with high specific surface area,which is more than twice that of TiO2/EP.Adding 2g·L-1 photocatalytic material to treat the Rhodamine B(10 mg·L-1)and Chromium(60 mg·L-1).The degradation rate can reach more than 90%,and can be recycled.It reveals the potential for environmental purification in practical applications.(2)This paper prepared photocatalyst which is co-doped with Ag、N and TiO2 loaded on expanded perlite.These materials were characterized by Scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET)and X-rav diffraction(XRD)for their structures.The photo catalytic properties of the as-synthesized materials were studied with Rhb for the target degrading substance.The results confirmed that Ag and N were loaded in the nanocomposites.The catalytic experiment revealed that Ag and N increased photolytic activity of TiO2 under visible light.There are a small number of micropores and macropores in the composites,and a large number of mesoporous materials exist at the same time.Upon doping nitrogen,the photocatalytic activity of the materials increased more and more,and the photocatalytic activity increased further when doping silver.The catalytic performance of the mole ratio of silver and titanium is the best at 0.50%.And the degradation rate of Rhb can reach 99.3%after 4h under ultraviolet light.The RhB degradation followed the first order kinetic model.(3)In this study,we prepared anatase TiO2 photocatalyst which is loaded on expanded perlite with zinc oxide doping.The as-synthesized materials were characterized by Scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),Fourier transform infrared spectrum(FT-IR)and Ultraviolet visible diffuse reflection(UV-VIS).The photocatalytic properties of the as-synthesized materials were studied by degradation of Rhb.The mechanism was also discussed.The results confirmed that the catalytic property was the best when the mole ratio of zinc and titanium is 0.4%.The degradation rate of Rhb can reach 99%after 4h under visible light when the initial concentration of Rhb is 10mg/L.The degradation of Rhb is characterized by pseudo-first-order kinetics.Hydroxyl radicals,superoxide radicals and hole were major active species for RhB degradation.