Study On Degradation Of DEP By TiO₂ Photocatalyst Loading With Polyoxometalate

TiO₂ nanoparticles have attracted much attention of the scientists as photocatalyst, which can be used to degrade the polluted gas and organic compound in the waste water, because TiO₂ produces photoexcited electrons(e^-) and holes(h⁺) which have the ability of strong oxidation.TiO₂ is hopeful to be widely used in the domain of environmental protection.New and efficient heterogeneous photocatalytic material,H₃PW₁₂O₄₀/TiO₂ with anatase crystalline phase was prepared by combination of the methods of sol-gel and hydrothermal treatment at a lower temperature(200℃,2℃/min).Composition,structure,physicochemical properties,and surface morphology of the composite were characterized by inductively coupled plasma atomic emission spectrum(ICP-AES),X-ray diffraction(XRD) patterns,UV diffuse reflectance spectroscopy(UV/DRS),nitrogen adsorption/desorption determination, and transmission electron microscopy(TEM),respectively.It indicated that the primary Keggin structure was intact in H₃PW₁₂O₄₀/TiO₂ catalyst,and the loading of H₃PW₁₂O₄₀ was 19.8%,and the particle size was 18nm.Moreover,the BET area of this material with dual-pore structures,micro- and meso-porosity,was increased obviously.In addition,the photocatalytic activity of Ag doped TiO₂ nanoparticles was studied. New and efficient heterogeneous photocatalytic material,H₃PW₁₂O₄₀/Ag-TiO₂ with anatase crystalline phase,was prepared by combination of the methods of sol-gel and hydrothermal treatment at a lower temperature(200℃,2℃/min).Composition,structure,physicochemical properties,and surface morphology of the composite were characterized same as the H₃PW₁₂O₄₀/TiO₂ catalyst.The research results showed that the particle size was 25nm,but the BET area of this material with dual-pore structures,micro- and meso-porosity,was decreased obviously.The introduction of Ag ion could make a obvious small shift toward longer wavelengths in absorption band edge(400～600nm) and improved the photoactivity. The improvement of the photocatalytic activity contributed to formation of doped energy.First of all,the effect of catalyst concentration and the initial concentration were investigated by using H₃PW₁₂O₄₀/TiO₂ as catalyst degraded of Rhodamine B in aqueous solution.The H₃PW₁₂O₄₀/TiO₂ and H₃PW₁₂O₄₀/Ag-TiO₂ and TiO₂ photocataly degradation of Rhodamine B in aqueous solutions under UV light irradiation were investigated respectively.Results showed that the degradation of Rhodamine B could achieve 99%,93% and 88%in 90 minutes.Moreover,the degradation of DEP under visible light irradiation could achieve 97%,60%and 40%in 60 minutes.The high photoactivity of as-prepared nanocomposite,H₃PW₁₂O₄₀/Ag-TiO₂,could be attributed the higher surface,dual-pore structures,and the synergistic effect existed between the H₃PW₁₂O₄₀,Ag ion and the TiO₂ matrix.