title: Decolorization of methylene blue in aqueous suspensions of titanium peroxide.
abstract: The pretreatment of TiO(2)-photocatalysts in solutions of H(2)O(2) was studied by examining the decolorization of methylene blue in the dark. Incubation of TiO(2) particles in H(2)O(2) solutions increased the oxidizing capacity of TiO(2). Methylene blue (0.3 mM) was degraded in the presence of pretreated TiO(2), and a decolorizing ratio of 47% was obtained after a 48-h incubation period in the presence of 5.0 g/L pretreated TiO(2). Titanium peroxide as a stable oxidant, which can be synthesized with the reaction of titanium sulfate and H(2)O(2), was studied in the decolorizing process of methylene blue. Concentrations of methylene blue were significantly reduced in the presence of titanium peroxide, and a greater extent of decolorization was obtained with larger amounts of titanium peroxide. A 63% decrease in methylene blue concentration was achieved in 5h incubation in the presence of 4.0 g/L titanium peroxide. H(2)O(2) accelerated the decolorizing process in the presence of titanium peroxide. The addition of 100 mM H(2)O(2) to a methylene blue solution containing 2.0 g/L titanium peroxide increased the decolorizing ratio to 85% after 5 h incubation. The addition of a hydroxyl radical scavenger, dimethyl sulfoxide, significantly decreased the decolorizing ratio, indicating the role of hydroxyl radicals in the oxidation process.
authors.affiliation: Division of Material Engineering, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ogino
authors.forename: Mahmoud Farshbaf
authors.initials: MF
authors.lastname: Dadjour
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Iida
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Shimizu
mesh_terms: D003116:Color; D004396:Coloring Agents / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008751:Methylene Blue / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010084:Oxidation-Reduction; D014025:Titanium / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D004396:Coloring Agents; D016166:Free Radical Scavengers; D016877:Oxidants; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D006861:Hydrogen Peroxide; D014025:Titanium; D008751:Methylene Blue; D004121:Dimethyl Sulfoxide