Preparation And Photocatalytic Performance Study Of Nanometer TiO₂ Particle And TiO₂ Pillared Clays

As a promising technique, photocatalysis is valuable for environmental cleaning and remediation. It has been applied in water treatment, gas purification, sterilization, and self-cleaning material. Photocatalyst is the key to photocatalytic technique. As the most frequently used semiconductor catalyst , TiO₂ has several advantages, such as low costs, high photocatalysis activity, strong oxidation capacity and stability to photocorrosion. The pitfall of TiO₂ is that the rapid electron-hole recombination results in decreasing its photocatalytic efficiency. Therefore, recombination of photogenerating electron-hole should be restrained to improve photocatalysis activity. Nano-photocatalysts can increase the migrating rate of electron-hole pairs from body to surface, reduce the recombination electron-hole pairs in body and enhance surface area, resulting in high adsorption capacity. Resently, many research groups have focused their attention on improving photocatalytic efficiency based on the preparation and texture modification of nanometer-TiO₂. A photocatalyst with small TiO₂ powder has to be removed from the degraded solution by centrifugation and filtration after the photocatalytic reaction is finished. To resolve this problem, the surfactant- modified TiO₂ with pillared montmorillonites can separate readily fom water and facilitate photocatalyst reuse. Furthermore, Inorganic-organic pillared montmorillonties have some merits, such as high photocatalytic activity, large surface area, strong adsorption capacity and special surface acidity. As a result, TiO₂ pillared clay is one of the new type and potential of complex photocatalytic materials.Chapter 1.Review on photocatalytic theory basis and TiO₂ pillared clayIt is summarized about photocatalytic theory , study on modified photocatalysts and clays, influence factors of TiO₂ pillared clays and application of pillared clays.Chapter 2.Texture modification and photocatalytic activity estimation of nanometer TiO₂ particleNanometer TiO₂ powder was prepared by the sol-gel technique using the tetra-n-butyl titanate as the main raw material and acetic acid as the acid catalyst. The size of nanometer TiO₂ was controlled at different ratios of Ti(OC₄H₉)₄: CH₃COOH: H2O. During preparation process of nano-TiO₂, dodecyl benzene sulfate sodium (DBS) and ethanol were added into the sol to improve the photocatalytic activity of nanometer TiO₂. Many modern analysis techniques, such as TEM and XRD, were used to characterize the structure and properties of the prepared photocatalyst. The photocatalytic activity of prepared TiO₂ was evaluated by using methyl orange as a mode organic pollutant. Moreover, the relation between structure of nano-photocatalyst and photocatalytic activity were discussed.Chapter 3.Effect of different mineral origins on the photocatalytic activity of surfactantsmodified TiO₂ pillared montmorillonitesThe surfactants modified TiO₂ pillared montmorillonites were prepared by sol-gel method at certain ratio of Ti(OC₄H₉)₄ to acetic acid by using different mineral origins montmorillonites, such as Hebei, Linan, Anji and Neimeng and modified by cation surfactant cetyltrimethyl ammonium bromide (CTMAB) at the same time. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to investigate the texture of prepared catalysts, and their BET surface areas were also measured in present paper. The result indicated that the pillared montmorillonites were well pillared by the anatase TiO₂ and the BET surface areas were larger than the original one. The sorption and photocatalytic performance of different prepared pillared clays were also studied by using methyl orange as mode organic pollutant.Chapter 4.Effect of different acid catalysts on the photocatalytic activity of surfactantsmodified TiO₂ pillared montmorillonitesOrganic-TiO₂ pillared montmorillonites were prepared with an intercalation of polynuclear titaniumcomplex at certain ratio of Ti(OC₄H₉)₄ to acetic acid or hydrochloric acid and different mineral origins montmorillon...