Development of titania nanotube films for degradation of the recalcitrant organic pollutants in water.

摘要

This research work was designed to develop titania nanotube (TNT) films as photocatalysts for the destruction of recalcitrant organic pollutants in water and wastewater. In this study different TNT films were prepared by an anodic oxidation process under various experimental conditions. The effects of nanotubular structures including tube length, tube wall thickness, and crystallinity on their photocatalytic activities were investigated with details. The experimental results showed that the large specific surface area and high pore volume, the thin tube wall, and the optimal tube length would be three important factors to achieve good performances. Moreover, the TNT films calcined at 500°C for 1 h exhibited the highest photocatalytic activities. These results indicate that the optimization of TiO2 nanotube structures is critical to achieve the high performance of photocatalytic reaction.;Research efforts were further focused on the effects of reaction factors including dissolved oxygen (DO), pH and anions on the photocatalytic activities of TNT films for the degradation of 2,3-dichlorophenol (2,3-DCP) in aqueous solution. A comparison study to evaluate the photolytic and photocatalytic degradation of herbicide diphenamid (DPA) in aqueous solution was also investigated. Furthermore, a new type of TNT film, polythiophene sensitized-TNT (PTh/TNT) photocatalyst, responsive to visible light, was successfully prepared by a two-step electrochemical method. These composite photocatalysts have a strong photoresponse in the visible region at 500 nm. The prepared PTh/TNT films revealed significant activities for 2,3-DCP degradation under visible light irradiation and also sunlight irradiation. The experiments also confirmed that the side-chains of polythiophene could influence its photocatalytic activities significantly.;Based on the results obtained in this study, there is better understanding of the photochemical reactions using TNT films as a photocatalyst for the degradation of organic pollutants in water.