Preparation Of The Mesoporous Nano-TiO₂ And Its Photocatalytic Activity

Objective: 1. To explore the novel mesoporous titanate hydrates and test its photocatalytic activity. 2. To explore the novel preparation for the mesoporous nano-TiO₂ and test its photocatalytic activity. 3. To explore the the novel path for the preparationof anatase TiO₂ and test its photocatalytic activity.Methods: 1.The hydrogen titanate hydrates with mesopore were prepared by dropping the titanium tetrachloride into the ethanediamine, then water was dropped into the flash containing Ti Cl4-ethanediamine. The result of the past was refluxed at 98 ℃and the hydrogen titanate hydrates with mesopore was obtained after centrifugal/washing and drying. The condition for the preparation of hydrogen titanate hydrates was optimized by varying the time, the ratio of the ethylenediamine/ water/titanium and so on. The photocatalytic activity of hydrogen titanate hydrates was tested using methylene blue as the photo-gradation model under UV irradiation by comparing its photo-catalytic activity with P25 and the hydrogen titanate hydrate nanotube. 2. The condition for the preparation of the nano-TiO₂ is same as the preparation of mesoporous hydrogen titanate hydrates besides the reaction temperature and apparatus, the flash was maitained at 180 ℃（in autoclave with Ptfe lined）. 3. The anatase nano-TiO₂ was prepared by dropping the titanium tetrachloride into the anhydrous acetonitrile, then water was dropped into the flash containing Ti Cl4-acetonitrile. The flash was refluxed at same temperature for 3-9 h and the anatase nano-TiO₂ powder was obtained after centrifugal and drying of the product. The photocatalytic activity of anatase nano-TiO₂ was tested using methylene blue as model under UV irradiation.Results: 1. The hydrogen titanate hydrates with mesopore centered at 3-4 nm was obtained at the conditions: the mole ratio between Ti Cl4 and ethylenediamine is1:8; the volume ratio between Ti Cl4 and water is 1:20 and the time of reflux is 72 h. Its surface area is 432.7 m2/g with a total pore volume of 0.731 m3/g and micropore volume of 0.151 m3/g. The obtained hydrogen titanate hydrates showed a higher photocatalytic activity than that of P25 and nanotube. 2.The nano-TiO₂ with mesopore centered at 3-4 nm was obtained at the fellow conditions: the mole ratio of Ti Cl4:ethylenediamine is 1:8; the volume ratio of Ti Cl4:water is 1:20 and the time of reaction is 12 h. Its surface area is 257.6 m2/g with a total pore volume of 0.461 m3/g and a micropore volume of 0.091 m3/g. The nano-TiO₂ showed a higher photocatalytic activity than that of P25. 3. The anatase TiO₂ was obtained at the fellow condition: the volume ratio of Ti Cl4:acetonitrile is 1:10; the volume ratio of Ti Cl4:water is 1:20 and the time of reflux is 3-9 h. Its surface area is 206.2 m2/g and the particle size distributed mainly in 3-4 nm. It showed a well photocatalytic activity to methylene blue. Conclusion: 1. Using Ti Cl4-ethanediamine as raw materials, the mesoporous hydrogen titanate hydrates was prepared successfully. 2. Using Ti Cl4-ethanediamine as raw materials, the mesoporous nano-TiO₂ was prepared by reacting at 180 ℃. 3. Using Ti Cl4-ethanediamine as raw materials, anatase nano-TiO₂ powder was prepared.