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Iron, lanthanum -doped nano TiO \u003csub\u003e 2 \u003c/ sub\u003e Preparation and photocatalytic properties

Author: HaoLiMeng
Tutor: FuMin
School: Chongqing Technology and Business University
Course: Environmental Engineering
Keywords: Titanium dioxide Sol-gel doping Photocatalysis Methyl orange Visible light
CLC: O614.411
Type: Master's thesis
Year: 2011
Downloads: 24
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Abstract


In recent years,much attention has been paid for heterogeneous photocatalysis owing to its potential application in many areas,especially the treatment of environmental pollution.TiO2 is paid the extensive attention at home and abroad,beause it is stable,cost effectiveandnon-corrosive.However,TiO2 as photocatalyst has some disadvantage,the photocatalytic activity of TiO2 is limited by fast charge-carrier recombination and its low quanta efficiency,the pure TiO2 absorbs only the small ultraviolet part(3-5%) of solar light due to its wide band-gap of 3.2ev.The lower quanta efficiency and wide bandgap are the main factors to restrict the practicality and industrialization of photocatalytic oxidation.Therefore, reducing the recombination of electron-cavity pairs,any improvement of photocataly -tic efficiency and utilization of visible light will have a profound effect.In our study,we modify the TiO2 by metal doping to improve the photocatalic ability and utilization of visible light.Fe3+、La3+ single doped TiO2 and Fe-La co-doped TiO2 were prepared by sol-gel method. Factors affecting TiO2 crystal composition,particle size and photocata -lyitc activity such as the raw material ratio,calcination temperatures. The structure shape and spectrum characteristic were characterized by XRD, XPS,FSand UV-Vis. The photocatalytic activities were evaluated by degradation of methyl orange.At the same time,we investigated the effect of doping on photocatalytic activity of TiO2 under ultraviolet and visible light.Furthermore,we analyed the reaction kinetic of organics photocatalytic degradation process.Nano-TiO2 was prepared by sol-gel method with C16H36O4Ti as forerunner body, glacial acetic acid as inhibitor,the doped samples calcined at 500℃presented anatase structure,the patricle size of Fe3+、La3+ doped TiO2 is smaller than pure TiO2 and the average size of the Fe3+、La3+ co-doped TiO2 is about 6.1nm. We consider that metal co-doped restrain the growth of crystal.Fe3+、La3+ co-doped changed the binding energy peaks of Ti and O,and Fe3+ doped into the TiO2 lattice,and the existence of La ion is in the form of La2O3,this also description that the sol-gel method can be effective to doped some Fe3+、La3+ into TiO2.UV-Vis results show that the absorption sideband of Fe3+、La3+ doped TiO2 has red-shift and widen the spectrum absorption range.The little fluorescence intensity,the lower recombination of electron-cavity pairs,and the better catalyze effect of the catalyst.The results show that the photocatalytic of Fe3+、La3+ doped TiO2 has been highly improved under ultraviolet or visible light,the optimal doping of La3+ is 0.6%,Fe3+ is 0.01%,and annealing temperature is 500℃.The co-doping of rare-earth and metal show a synergistic effect for photocatalyic activity of TiO2.The co-doped TiO2 show higher photocatalytic activity in degradation of methyl orange than that of single doped TiO2.Titania co-doped with Fe-La for n(La):n(TiO2)=0.6%, n(Fe):n(TiO2) =0.01% have higher photocatalytic efficiency. Fitting cuve of methyl orange photocatalytic degradation show that the reaction kinetics of rare-earth doped TiO2 is according with the first order reaction equation of Langmuir-hinshelwood.

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CLC: > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Metal elements and their compounds > Section Ⅳ group metal elements and their compounds > The titanium Vice family ( IV B group metal elements) > Ti Ti
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