In This study a thin film of nanometric TiO2 was sol-gel prepared and used for heterogeneous photocatalytic reaction to treat chlorobenzene in testing solution and to evaluate its removal efficiency. Conventionally, the material of photocatalyst was mainly fabricated in form of powder used in the suspension system. Although TiO2 powder has a high specific surface area for heterogeneous photocatalysis, it still leaves a great number of suspended solids in solution awaiting proper handling after the treatment is completed. Also, such suspended solids would pose ¡§shielding¡¨ effect from UV light, and thus affected the efficiency of photocatalytic degradation. To overcome this drawback, a proper mesh size of stainless steel webnet was first selected as a treatment substrate and TiO2 dip-coated, followed by calcination at 500¢J. The end product was used as the TiO2 photocatalytic film for this study. The film of TiO2, verified as anatase type of crystal lattice by XRD and SEM, contained particle sizes ranging from 10 to 20 nm. A solution containing chlorobenzene was used in the study to assess the extent of photocatalytic degradation by UV/TiO2 film. The test was to evaluate the effects of the number of dip-coating and calcining (thickness), initial pH, UV light intensity (@365 nm), and applied electric voltage on photocatalytic removal of chlorobenzene in the solution. The test results indicated that TiO2 film was capable of degrading chlorobenzene; however, enhancement of the degradation efficiency was found to be needed. It was also found that the degradation rate of chlorobezene increased with an increasing thickness of the film and UV light intensity. The pH of test solution was found to be insensitive to degradation of chlorobenzene, probably due to its non-dissociation nature. It was found that electric voltage exerted was unable to prevent electrons and holes from re-combining, and a negative effect of external voltage was even observed. Therefore, it was believed that voltage exertion was not beneficial to phtocatalysis in this study. Kinetics of the tests in this study assumed a pseudo-first-order reaction, which resulted in a rate constant k' = 1.3¡Ñ10-5¡]min-1¡^. The reaction rate was found to be proportional to the 0.7507 order of UV light intensity.

In the work, photocatalytical treatment of acetic acid wastewater by nanostructured film of TiO2 under ultra-violet ¡]UV¡^ light illumination was studied. Nanosized TiO2 suspension was prepared by the sol-gel process. Then it was dip-coated on indium tin-oxide¡]ITO¡^glass, which could be used as the anode if applicable. Effects the UV light intensity, UV light wavelength, reactive area of TiO2 film, solution pH, and applied bias voltage on photocatalysis efficiency of acetic acid in term of COD removal were studied in this work. Experimental results have shown that a pseudo first-order kinetics was obeyed in all tests. In this study UV light of 312nm outperformed that of 365nm ¡]15.3¢H vs. 11.0¢H¡^. UV light intensity of 20W was also found to be superior to 10W with COD removal of 11.0¢H against 6.7¢H. COD removal at pH¡×3.18 was about 3.6 times greater as compared with that of at pH=9.98. When the reactive area of TiO2 film was increased to three times, the COD removal was almost doubled. An applied external voltage was found to enhance the removal of COD. When an external voltage of 15V was applied, the COD removal was increased to 84.6¢H. It is ascribed to an external voltage would prevent or lower the extent of electron-hole recombination. In this work, the pseudo first-order reaction rate equation K¡¬=1.7679(COD)-0.7547 was obtained for various concentrations of acetic acid tested.