The Research On Application And Preparation Of Nanometer Doped Titanium Dioxide

Due to chemical stability, non-toxic, low cost, nano-TiO₂ has a wide range of applications as a photocatalyst semiconductor material. But the TiO₂ only absorb the UV part of sunlight, and the photogenerated electrons and holes easily combined, therefore, the photocatalytic efficiency is not high. Doped to improve the efficiency of TiO₂ photocatalysis is an effective means of instruction. In this study, the WO₃ and Fe³⁺ doped TiO₂ particles to improve the photocatalytic properties of TiO₂.The research tetrabutyl titanate as precursor, sol-gel nano-TiO₂, nano-WO₃/TiO₂ and nano-Fe³⁺/TiO₂ powder, and making the use of transmission electron microscopy (TEM), X-ray diffraction (XRD), photocatalytic properties to characterize the powder particle's size, morphology and photocatalytic properties. Using thermogravimetry analyzer in this research, the thermal behavior of nano-TiO₂ and nano-WO₃/TiO₂ powder was studied by means of and Kissinger method under the differernt heating rate of 10K/min, 15K/min, 20K/min, 40K/min. The results show that, decomposable activation energy of nano-TiO₂ is 94.014KJ/mol, and decomposable activation energy of nano-WO₃/TiO₂ is 98.680KJ/mol. Photocatalytic degradation of methylene orange(5mg/L,pH=4) experiments to test photocatalytic effect the of pure nano TiO₂ powders,nano WO₃/TiO₂ and nano Fe³⁺/TiO₂ powders,and the amount of photocatalyst powder is 0.0200g in the test. The experimental results demonstrate that 550℃calcined TiO₂ particle size is about 13.5nm, and the particles are spherical, and its photocatalytic properties of the sample are better than the other samples calcined in other temperatures, the degradation of methylene orange was 90.54%.Sol-gel prepared WO₃ doped TiO₂ nano-powder particles are fine and uniform, and the appearance is spherical, and the average diameter is about 9nm. Through the photocatalytic properties test of the samples, WO₃/TiO₂ nano-powder particles calcined at 550℃get better photocatalytic performance,and the degradation of methylene orange is 95.60%. Sol-gel prepared Fe doped TiO₂ nano-powder particles has the uniform and spherical appearance, and an average size is about 13.5nm. Through the photocatalytic properties test of the samples, Fe³⁺/TiO₂ calcined at 550℃has better photocatalytic performance, and the degradation of methylene orange is 93.21%。In this study, nano-TiO₂ photocatalyst used in the RDX wastewater treatment. When pH is about 3 to 4, 20mL 200mg/L RDX wastewater is photocatalysised by 0.0200g TiO₂ under UV light after 5 hours, the degradation of RDX wastewater can reach 51.03%, COD value decreased 54.51%. Combined TiO₂ with O₃ to treat RDX wastewater. Under the alkaline conditions to treat with O₃ 15min, then adjust to acidity condition and catalytic the 20mL 200mg/L RDX wastewater by 0.0200g TiO₂ under UV light after 0.5h, and the degradation of nitro compounds to achieve 75.70%, COD value decreased 98.86%. Using the O₃/TiO₂ to treat with RDX wastewater reduced greatly the degradation time, which indicating that the O₃/TiO₂'s catalytic performance was significantly better than TiO₂ catalyst.