Different Temperature Heat Treatment Nano-tio <sub> 2 </ Sub> Photocatalyst Degradation Of Organic Matter Of A Single Benzene Ring

Worldwide environment pollution and energy crisis are two of the most serious problems humans confront in the 21st century. Titanium dioxide photocatalyst, which can absorb a small fraction of the sun radiation, is able to oxide most organic contaminants into harmless products such as CO₂, H₂O and mineral acid,etc. Furthermore, titanium dioxide photocatalyst has attracted extensive interests in the fields of materials, chemistry and environmental science because of its excellent performance such as high photocatalytic reactivity, chemical stability, low cost and nontoxicity, etc.In this dissertation, nanosized titanium dioxide photocatalyst with high visible-light ( λ≥450 nm) photocatalytic activity was successfully prepared by high-temperature hydrolysis solvothermal method, using titanium tetra-n-butoxide(TNB) as precursor and acetone as solvent. Degradation processes and kinetics of several mono-benzonic derivatives have been analyzed. Furthermore, the mechanisms and kinetics of photocatalysis of titanium dioxide after different temperature treatment have been investigated using different wavelength light radiation sources. Also, the relation between the surface adsorption status of the as-prepared samples and their photocatalytic activities had been discussed. Finally, valuable results on visible-light photocatalysis of present nanosized titanium dioxide photocatalysts were obtained, which will contribute to the aspects both for theory research and practical application of nanosized titanium dioxide with high photocatalytic activity using visible light radiation.UV-Visble light (UN-Vis) photocatalytic activity decreases in the sequence of P25,A-240-365,A-240-180,A-240, indicating that UV-Vis photocatalytic activity increases as surface organic compounds are desorbed gradually. The higher photocatalytic activity of P25 using UV-Vis radiation may attribute to the mixture phases of anatase and rutile. However, visible light photocatalytic activity decreases in the sequence of A-240-180,P25, A-240-365 > which may due to the different surface status of photocatalysts after thermal treatment at different temperatures. Compared to P25, as-prepared A-240-180 sample has much higher photocatalytic activity for phenol, 4-chlorophenol and /?-hydroxybenzoic using visible light radiation, respectively. As for the different compounds and photocatalysts, the photocatalytic rate constants are also obviously different. In addition, the photo degradation rates change when different initial concentrations of phenol were applied for measurement. All above results indicate that photocatalytic degradation processes of organic pollutants are obviously affected by structures of organic compounds and their initial concentrations.