title: Establishment of activity indicator of TiO2 photocatalytic reaction--hydroxyl radical trapping method.
abstract: In this study, a new, low cost and easy method, hydroxyl radical trapping method, was employed to investigate the photo-activity of UV/TiO2 photocatalytic reaction. The Taguchi method was utilized to optimize the preparation of titanium dioxide (TiO2) thin-film reactor through the modified chemical vapor deposition (CVD) method. The optimal yield of hydroxyl radicals was then evaluated by calculating the conversion ratio of salicylic acid under the optimal conditions. In the experiments, salicylic acid was used as the free-radical scavenger and the formation of three different intermediates were examined to shed light on the trend and kinetics of reaction of hydroxyl radical with organic substance under different operation conditions. The results indicated that the yield of hydroxyl radicals increased with increasing irradiation intensity and dissolved oxygen level. The optimal experimental conditions obtained in this study were irradiation with intensity of 2.9 mW cm(-2) on salicylic acid at concentration of 250 mg L(-1) by both agitation and aeration processes (dissolved oxygen level=8.2 mg O(2)L(-1)) at pH 5. Such conditions could achieve the optimal hydroxyl radical yield of 5.1 x 10(-17)M.
authors.affiliation: Department of Life Science, Ming-Dao University, 369 Wen-Hua Road, Peetow, Chang-Hua County 52345, Taiwan. cychang@mdu.edu.tw
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Chang
authors.forename: Yung-Hsu
authors.initials: YH
authors.lastname: Hsieh
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Hsieh
authors.forename: Kuo-Shan
authors.initials: KS
authors.lastname: Yao
authors.forename: Ta-Chih
authors.initials: TC
authors.lastname: Cheng
mesh_terms: D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D010100:Oxygen / Q000737:chemistry; D055668:Photochemical Processes; D020156:Salicylic Acid / Q000737:chemistry / Q000528:radiation effects*; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: C009495:titanium dioxide; D017665:Hydroxyl Radical; D014025:Titanium; D020156:Salicylic Acid; D010100:Oxygen