Hydrothermal Preparation And Potocatylci Activity Of Differnt Morpholgy Titanian

In recent years, tremendous harm has been brought to ecological environment by the large amount of industrial wastewater discharge, and how to control pollution has become a focus of attention around the world. Heterogeneous semiconductor photocatalysis has high efficiency and unique advantage in water pollution control, especially in degrading organic pollutants in wastewater. Among the oxide semiconductor materials, nano-Titanium dioxide (TiO₂) as excellent photocatalyst has become a hotspot in the research of environmental pollution treatment for its strong oxidization, non-toxicity and long-term stability.The present studies are mostly focused on the modification of nano-sized TiO₂ to improve its photocatalystic activity. But the nano-sized photocatalyst powder is hard to recover in liquid system and that increases the costs of wastewater treatment. The aim of this paper is to control the size and morphology of TiO₂ within micro-size, and realize TiO₂ photocatalyst can be easily recycled with successful photocatalystic property. The main contents of this thesis are as follows:1. Titanate with large specific surface area was prepared by hydrothermal treatment of steady rutile TiO₂, and then the multiphase mesoporous TiO₂ flaky crystals were obtained after calcining. The samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and nitrogen adsorption/desorption analysis. The effect of different reaction parameters on the morphology and crystallinity was studied, such as reaction temperature, concentration and so on, and the forming mechanism of TiO₂ flaky crystals were proposed. The results indicated that the photocatalytic property of TiO₂ flaky crystals are better than that of P25, a famous commercial nano-photocatalyst produced by Degussa, Germany. One-dimensional TiO₂ can be synthesized by controlling the reaction temperature, and small addition of Co metal ions help to synthesis of one-dimensional TiO₂ at low-temperature.2. TiO₂ photocatalyst were prepared in different media (H2O and NaOH with different concentration) by hydrothermal method using the hydrolysis product of tetrabutyl titanate (TBOT) as precursor. The results indicated that the multiphase TiO₂ powder prepared using 10M alkali (NaOH) solution as medium has better photocatalytic property. The research also found that using water as medium, the photocatalytic activity of sample is much higher after calcined.3. Anatase TiO₂ micro-particles with high photocatalytic activity were prepared by one-step HF-assisted hydrothermal method using TBOT as precursor. The results indicated that the average particle size of the anatase TiO₂ lies in 20³0μm, whose degradation rate for methyl orange can be up to 95% after 30 min reaction. This is superior to that of P25. Moreover, the micro-sized TiO₂ particles can solid-liquid separation easily by natural sedimentation, which facilitates recycling and reuse.