Studies Of TiO₂ Nano-material And Photocatalytic Degradation Of Organic Contamination

Since 1980s, biotechnology, new materials and information technology have been regarded as the symbols of technical innovation, which are important to the areas of population, environment, food, energy, health and so on. This dissertation focuses on the areas of materials, environment science and life science. We studied the application of in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy in analysis of mechanism of ethanol oxidation by TiO2 under UV light, and in the study of biodegradation of naphthalene by Pseudomonas aeruginosa. Using ultraviolet-visible spectrophotometer to study the reaction of Cr6+ reduction and resorcin oxidation by TiO2 under visible light.(1) The photocatalytic oxidation of ethanol over TiO2 nanotubes (NTs) was investigated by in situ attenuated total reflection using Fourier transform infrared spectroscopy (ATR-FTIR) and ultraviolet (UV)-visible spectroscopy. In the ATR-FTIR study, the TiO2 NTs were spread in a ZnSe crystal trough which was used as the reactor. The evolution of the reaction under UV irradiation was investigated by in situ monitoring of changes in the species at the surface of the TiO2 NTs. Ethanol adsorbed on the TiO2 NTs surface at room temperature, forming alkoxide and hydroxide groups (960 cm-1 and 920 cm-1) which were then attacked by ?OH, with the formation of a vinyl alcohol intermediate that was finally transformed to acetic acid. In addition, the species changes in the reaction solution were also investigated by in situ UV-visible spectroscopy using a small volume flow-through cell. The UV-visible data further confirmed the oxidation mechanism of ethanol on TiO2 NTs elucidated by ATR-FRIR data.(2) Here we report the simultaneous Cr6+ reduction and resorcin oxidation in water under visible light using TiO2 doped with W. This remarkable observation was attributed to a synergistic effect among TiO2, Cr6+, and resorcin. It's well known that TiO2 cannot remove either Cr6+ or resorcin efficiently under visible light. But we found that the combination of TiO2, Cr6+ and resorcin together can enable efficient Cr6+ reduction and resorcin oxidation under visible light. The specific roles of the three ingredients in the synergistic system were studied parametrically. The mount of resorcin removed was directly related to the initial concentration of Cr6+).(3) Polycyclic aromatic hydrocarbons (PAHs) was a kinds of environmental contamination which cannot be degradation easily, except by microorganism. Here we used Pseudomonas aeruginosa as the typical microorganism to biodegradation naphthalene using in-situ attenuated total reflectance Fourier transform infrared (ATR-FTIR). And successfully observed the continuous degradation of naphthalene by Pseudomonas aeruginosa, and the good growth and cling of Pseudomonas aeruginosa on the surface of ZnSe.