Preparation, Properties And Degradation Mechanism Of The Photocatalytic Materials Titanium Dioxide Nanotubes

The rapid development of industry brings kinds of environmental issues, thepollutants of human production and life have been released into the water, which isharmful to human health. Titanium dioxide with high photocatalysis activity,corrosion resistance, non-toxicity and low cost, which is widely used to remove theorganic pollutants in waste water, as one of the advanced oxidation processes, thesynergistic effect of ozone and photocatalysis gives our light to high concentrationswastewater treatment.In order to improve the photocatalytic activity of TiO₂, titanium dioxidenanotubes （TNTs） was prepared using classical hydrothermal method, the prepraredTNTs shows large specific surface area, pure anatase. The effects of pH of thesubstrate solution and light source on the degradation of Brilliant Red X-3B （X3B）, ananionic azo dye, were evaluated. Adsorption and photocatalytic degradation of X3Bwere studied using O₂and O₃as oxidants, and TNTs and P25as photocatalysts,respectively.This paper is divided into four chapters: the first chapter details the backgroundintroduction of photocatalysis titanium dioxide nanotubes, the synergistic effect ofozone and photocatalysis, adsorption influence and the separation and identification ofdegradation products. The background and research plan of this study are alsopresented. In the second chapter titanium dioxide nanotubes were synthesizedsuccessfully by hydrothermal method. The prepared TNTs were characterized byTEM, XRD and BET. The degradation of different pH of the X3B with titaniumdioxide nanotubes under ultraviolet light, xenon lamp and visible light were studied.The results indicate the ultraviolet light as the light source and the pH value of thesystem for7, the degradation rate of X3B was99%after1.5h, is the best degradationconditions. The third chapter examined the effect of X3B degradation by differentoxygen source, air and ozone respectively, contrasts catalytic performance of P25andTNTs in different degradation system, and detects the hydroxyl radicals differentsystem through the fluorescence, studies show that the synergistic effect of ozone and photocatalysis, but hydroxyl radicals concentration is not main influencing factors.The fourth chapter investigates the adsorption of X3B on P25and TNTs, it was foundthat the maximum adsorption of X3B on the surface of TNTs is2.82times higher thanthat of P25. Studying the Langmuir-Hinshelwood kinetics, we suggeste that thedegradation reaction occured on the catalyst surface. Through the quenches test ofhole and hydroxyl radicals, we conjecture that hole oxidation and direct ozonizationare the main reaction paths, reflecting the importance of adsorption on the degradationof organic pollutant. The fifth chapter examines enrichment separation of thedegradation products, through the GC-MS qualitative tests, and concludes that thepossible degradation products formula.