Evidence for the Active Species Involved in the Photodegradation Process of Methyl Orange on TiO2

Active species such as holes, electrons, hydroxyl radicals (•OH), and superoxide radicals (O2•–) involved in the photodegradation process of methyl orange (MO) over TiO2 photocatalyst were detected by several techniques. Using different types of active species scavengers, the results showed that the MO oxidation was driven mainly by the participation of O2•–, holes and •OH radicals. Characterized by the liquid chromatography/mass spectrometry, the transversion of the degradation products with the light irradiation time was first analyzed. Combined with the measurement of oxidation reduction potential, dissolved oxygen, conductivity, and pH values, the degradation process of MO on TiO2 under the effect of the active species was revealed. This was the first time that electrodes were introduced to track the degradation process in situ, and these parameters would be helpful to explain the degradation processes of other organic pollutants.

[1]  D. Chatterjee,et al.  Photoassisted detoxification of organic pollutants on the surface modified TiO2 semiconductor particulate system , 2001 .

[2]  T. Morimoto,et al.  Molecularly adsorbed water on the bare surface of titania (rutile) , 1987 .

[3]  M. Crocker,et al.  1 H NMR spectroscopy of titania. Chemical shift assignments for hydroxy groups in crystalline and amorphous forms of TiO2 , 1996 .

[4]  J. White,et al.  Characterization of species adsorbed on oxidized and reduced anatase , 1982 .

[5]  Chuncheng Chen,et al.  Photocatalysis by titanium dioxide and polyoxometalate/TiO2 cocatalysts. Intermediates and mechanistic study. , 2004, Environmental science & technology.

[6]  K. Lv,et al.  Effects of polyoxometalate and fluoride on adsorption and photocatalytic degradation of organic dye X3B on TiO2: the difference in the production of reactive species. , 2006, The journal of physical chemistry. B.

[7]  S. Martin,et al.  Environmental Applications of Semiconductor Photocatalysis , 1995 .

[8]  J. Freer,et al.  Evidence for hole participation during the photocatalytic oxidation of the antibiotic flumequine , 2008 .

[9]  David F. Ollis,et al.  Photocatalytic degradation of organic water contaminants: Mechanisms involving hydroxyl radical attack , 1990 .

[10]  J. A. Hockey,et al.  Infra-red studies of rutile surfaces. Part 2.—Hydroxylation, hydration and structure of rutile surfaces , 1971 .

[11]  H. Boehm.,et al.  Über die Chemie der Oberfläche des Titandioxids. I. Bestimmung des aktiven Wasserstoffs, thermische Entwässerung und Rehydroxylierung , 1967 .

[12]  Mita,et al.  Surface Hydroxyl Site Densities on Metal Oxides as a Measure for the Ion-Exchange Capacity. , 1999, Journal of colloid and interface science.

[13]  A. Fujishima,et al.  Generation and Deactivation Processes of Superoxide Formed on TiO2 Film Illuminated by Very Weak UV Light in Air or Water , 2000 .

[14]  Akira Fujishima,et al.  Titanium dioxide photocatalysis , 2000 .

[15]  B. Ohtani,et al.  Mechanism of photocatalytic production of active oxygens on highly crystalline TiO2 particles by means of chemiluminescent probing and ESR spectroscopy , 2001 .

[16]  X. Verykios,et al.  Visible light-induced photocatalytic degradation of Acid Orange 7 in aqueous TiO2 suspensions , 2004 .

[17]  C. Minero,et al.  Role of adsorption in photocatalyzed reactions of organic molecules in aqueous titania suspensions , 1992 .

[18]  P. Pichat,et al.  Probing the TiO2 Photocatalytic Mechanisms in Water Purification by Use of Quinoline, Photo-Fenton Generated OH• Radicals and Superoxide Dismutase† , 1997 .

[19]  M. Primet,et al.  Infrared study of the surface of titanium dioxides. I. Hydroxyl groups , 1971 .

[20]  H. Boehm.,et al.  Acidic and basic properties of hydroxylated metal oxide surfaces , 1971 .

[21]  Y. Nosaka,et al.  Factors Governing the Initial Process of TiO2 Photocatalysis Studied by Means of in-Situ Electron Spin Resonance Measurements , 1998 .

[22]  J. R. Darwent,et al.  Photoreduction of methyl orange sensitized by colloidal titanium dioxide , 1984 .

[23]  WuXing-Zheng,et al.  Time-resolved Chemiluminescence Study of Photocatalytic Reaction of TiO2 , 2003 .

[24]  H. Mansilla,et al.  Evidence for superoxide-radical anion, singlet oxygen and OH-radical intervention during the degradation of the lignin model compound (3 -methoxy -4 -hydroxyphenylmethylcarbinol) , 2005 .

[25]  B. Lee,et al.  Influence of hydroxyl contents on photocatalytic activities of polymorphic titania nanoparticles , 2009 .

[26]  R. Qiu,et al.  Role of oxygen active species in the photocatalytic degradation of phenol using polymer sensitized TiO2 under visible light irradiation. , 2009, Journal of hazardous materials.

[27]  D. Bahnemann,et al.  Photocatalytic water treatment: fundamental knowledge required for its practical application. , 2004, Water science and technology : a journal of the International Association on Water Pollution Research.

[28]  C. Pulgarin,et al.  Relationships between physicochemical properties and photoreactivity of four biorecalcitrant phenylurea herbicides in aqueous TiO2 suspension , 2002 .

[29]  A. Reller,et al.  Photoinduced reactivity of titanium dioxide , 2004 .

[30]  M. Yoon,et al.  Synthesis of Liposome-Templated Titania Nanodisks: Optical Properties and Photocatalytic Activities , 2005 .

[31]  B. Ohtani,et al.  Effective Photocatalytic Reduction of Nitrate to Ammonia in an Aqueous Suspension of Metal-Loaded Titanium(IV) Oxide Particles in the Presence of Oxalic Acid , 2001 .