| Nano-titanium dioxide is a material which has high photocatalytic efficiency, can catalyze a variety of pollutants, nontoxic, mild reaction conditions and the operation is simple and could reduce secondary pollution ,so it will have potential applications in in wastewater treatment, air purification, disinfection antibacterial and many other fields for the future. However the pure TiO2 absorbs only the small ultraviolet part(3%-5%) of solar light due to its wide band-gap of 3.2ev.Therefore , it has become a crueial issue in the researeh field of TiO2 photoeatalysis to make the Ti02 responding to the range of visible radiation wavelengths through adoping to improve its use of light.The nonmetal and the metal co-doped titanium dioxide catalyst are prepared Fe-N-co-doped TiO2 by sol-gel method. Factors affecting nano-TiO2 crystal composition, particle size and photocatalyitc activity such as the mole ratio, calcinations'temperatures . Through photocatalytic degradation of methylene blue and malachite green in the laboratory the process and conditions of preparation of Ti02 powder is determined. The XRD, XPS, FT-IR, FS and UV-Vis are use to characterize the titania nanopowder.(1) Iron and nitrogen codoped nano-TiO2 was prepared by sol-gel method with C16H36O4Ti , urea and Fe(NO3)3.9H2O as forerunner body, ethanol as solvent and glacial acetic acid as inhibitor. As compared with other doping methods,this method is lower energy-consuming and easily manipulated,ensuring the uniform dispersal of adorning ion.(2) XRD, XPS, DSC, UV-Vis and FS used to characterize of the samples .The XRD and DSC can tell us that calcining temperature had important effect on the crystal phase and particle size of co-doped TiO2, the doped samples exhibited anatase structure at 500℃, and had minimum size, when temperature rised, the crystal sizes of the samples increased, and rutile phase started to appear and its relative abundance increased. The XPS can tell us that Co-doped changed the binding energy peaks of Ti and O,and the ions doped into the TiO2 lattice, interact with TiO2, also 6% N and 0.9% Fe can doped into the TiO2 lattice, this also description that the sol - gel method can be effective to doped irons into TiO2.Compared with TiO2 the doping of N,Fe made the response light energy decrease to visible light;And also the fluorescence spectrum token that the little fluorescence intensity, the better catalyze effect of the specimen.(3)Compared with TiO2, The co-doped TiO2 had obviously visible light activity. When the Fe/Ti molar ration of 1%, the dosage is 2g/l and the pH=8.2, the photo catalytic degradation of methylene blue appears obvious is the best. The best rate for decolorization of methylene blue can reach to 92% in 2 hours under 40W UV lamp and 60% in 5h under 35Wxenon lamp when the concentration is 20mg/l,and the rate for decolorization of malachite green can reach to 100% in 2.5 hours under 40W UV lamp. |
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