Study On Preparation Of Nitrogen-Doped Titanium Dioxide And Photocatalytic Degradation Of Benzoic Acid By Nitrogen-Doped Titanium Dioxide

Titanium dioxide has been extensively studied as a wider gap photocatlytic material because of its long-term stability, nontoxicity and high photoctalytic activity in the photocatalytic field. However, the band gap of TiO₂ (anatase) is 3.2ev and the photocatalytic reaction proceeds under the UV illumination with wavelengths shorter than 387.5nm. But UV light accounts for only a small fraction (4%) of the sun's energy compared to visible light (43%). Hence, the development of photocatalyst that can show photocatalytic activity under solar irradiation, and even poor illumination of interior lighting will be very valuable. Many approaches have been proposed to modify TiO₂ in order to shift the optical response of TiO₂ from UV to the visible spectral rang. An effective approach to shifting the optical response of TiO₂ from the UV to the visible spectral range is doping with nonmetal nitrogen.In this paper, nitrogen-doped TiO₂ are prepared by hydrolyzing TNB method. The best preparation condition of nitrogen-doped TiO₂ is obtained by orthogonal experiment. The surface structural, photoelectric properties and mechanism of influence induced by nitrogen doping on photocatalytic performance of nitrogen-doped TiO₂ are characterized by XRD, BET, XPS, IR, SPS and DRS. It is found that the O site in TiO₂ lattice is substituted N atom and Ti-N band is formed, results in the band-gap narrowing and the absorption edge red shifting for nitrogen-doped TiO₂ and the photocatalytic increasing of particle size, also can redound to get more hydroxyl radicals (OH), enhanceing the photocatalytic activity of TiO₂. With the increment of calcination temperature, the amount of N decreases constantly. The N-doped TiO₂ powder with the maximum amount of N and with the highest photocatalytic activity is obtained by calcination at 350℃.The befitting degradation condition of the benzoic acid at lower concentration is studied by optimizing the influence factors: concentration of N/TiO₂ photocatalyst, pH value of reaction system, initial concentration of benzoic acid and wavelength. The results show: the optical reactive-conditional parameter of TiO₂ suspension system photo-oxidation degradation benzoic acid are: concentration of N/TiO₂ photocatalyst is 0.3g/L; pH value of reaction system...