Degradation of dye pollutants by immobilized polyoxometalate with H2O2 under visible-light irradiation.

A Keggin polyoxometalate (POM, i.e., PW12O40(3-)) and its lacunary derivative are immobilized on an anionic exchange resin through electrostatic interaction at pH 4.6 in an aqueous dispersion. The resin-supported POM thus obtained catalyzes the efficient degradation of cationic dye pollutants in the presence of H2O2 under visible-light irradiation. To evaluate the photocatalytic system, degradation of a rhodamine B (RB) dye was investigated in detail using UV-visible spectroscopy, high performance liquid chromatography, and gas chromatography/mass spectrometry techniques to identify the intermediates and final products. Fluorescence lifetime measurements revealed the electron transfer from the visible-light-excited RB molecules to the POMs. Electron paramagnetic resonance measurements, investigation of the effects of *OH and *OOH scavengers on the photoreaction kinetics, and IR analysis indicated that de-ethylation of RB was due to *OOH radicals, but the decomposition of the conjugated xanthene structure was caused by the peroxo species formed by interaction of H2O2 with the lacunary POM loaded on the resin. A total organic carbon removal of ca. 22% was achieved, and the recycle experiment suggested excellent stability and reusability of the heterogeneous catalyst. On the basis of the experimental results, a photocatalytic mechanism is discussed.

[1]  R. Neumann,et al.  Synthesis of dendritic polyoxometalate complexes assembled by ionic bonding and their function as recoverable and reusable oxidation catalysts. , 2004, Angewandte Chemie.

[2]  Hyunwoong Park,et al.  Comparative Study of Homogeneous and Heterogeneous Photocatalytic Redox Reactions: PW(12)O(40)(3-) vs TiO(2). , 2004, The journal of physical chemistry. B.

[3]  Chuncheng Chen,et al.  Photosensitized degradation of dyes in polyoxometalate solutions versus TiO2 dispersions under visible-light irradiation: mechanistic implications. , 2004, Chemistry.

[4]  R. Neumann,et al.  New heterogeneous polyoxometalate based mesoporous catalysts for hydrogen peroxide mediated oxidation reactions. , 2004, Journal of the American Chemical Society.

[5]  A. Bond,et al.  Photophysical and novel charge-transfer properties of adducts between [RuII(bpy)3]2+ and [S2Mo18O62]4-. , 2003, Inorganic chemistry.

[6]  Young-Uk Kwon,et al.  Incorporation of Decavanadate Ions into Silica Gels and Mesostructured Silica Walls , 2003 .

[7]  M. Sastry,et al.  Keggin ions as UV-switchable reducing agents in the synthesis of Au core-Ag shell nanoparticles. , 2003, Journal of the American Chemical Society.

[8]  Keigo Kamata,et al.  Efficient Epoxidation of Olefins with ≥99% Selectivity and Use of Hydrogen Peroxide , 2003, Science.

[9]  Wanhong Ma,et al.  Photooxidation of azo dye in aqueous dispersions of H2O2/α-FeOOH , 2002 .

[10]  A. Hiskia,et al.  Synthesis of metal nanoparticles by using polyoxometalates as photocatalysts and stabilizers. , 2002, Angewandte Chemie.

[11]  Chuncheng Chen,et al.  Photodegradation of Sulforhodamine-B Dye in Platinized Titania Dispersions under Visible Light Irradiation: Influence of Platinum as a Functional Co-catalyst , 2002 .

[12]  J. Ferry,et al.  Photocatalytic Oxidation of Aqueous 1,2-Dichlorobenzene by Polyoxometalates Supported on the NaY Zeolite , 2002 .

[13]  S. Horikoshi,et al.  Environmental remediation by an integrated microwave/ UV-illumination method. 1. Microwave-assisted degradation of rhodamine-B dye in aqueous TiO2 dispersions. , 2002, Environmental science & technology.

[14]  Zhanghua Wu,et al.  Photocatalytic degradation of aqueous 4-chlorophenol by silica-immobilized polyoxometalates. , 2002, Environmental science & technology.

[15]  A. Hiskia,et al.  Comparison of the Photoredox Properties of Polyoxometalates and Semiconducting Particles , 2001 .

[16]  W. Griffith,et al.  Polyoxometalate catalysis of dye bleaching by hydrogen peroxide , 2001 .

[17]  M. Yoon,et al.  Heteropoly Acid-Incorporated TiO2 Colloids as Novel Photocatalytic Systems Resembling the Photosynthetic Reaction Center. , 2001 .

[18]  X. Zuwei,et al.  Reaction-controlled phase-transfer catalysis for propylene epoxidation to propylene oxide. , 2001, Science.

[19]  Changwen Hu,et al.  Microporous Polyoxometalates POMs/SiO2: Synthesis and Photocatalytic Degradation of Aqueous Organocholorine Pesticides , 2000 .

[20]  S. Lindeman,et al.  Novel Charge-Transfer Materials via Cocrystallization of Planar Aromatic Donors and Spherical Polyoxometalate Acceptors , 2000 .

[21]  Jincai Zhao,et al.  Photooxidation Pathway of Sulforhodamine-B. Dependence on the Adsorption Mode on TiO2 Exposed to Visible Light Radiation , 2000 .

[22]  C. Minero,et al.  Light induced elimination of mono-and polychlorinated phenols from aqueous solutions by PW12O403-. The case of 2,4,6-trichlorophenol , 2000 .

[23]  A. López,et al.  Photochemical Decoloration of Remazol Brilliant Blue and Uniblue A in the Presence of Fe3+ and H2O2 , 1999 .

[24]  C. Langford,et al.  The Photooxidative Degradation of N-Methylpyrrolidinone in the Presence of Cs3PW12O40 and TiO2 Colloid Photocatalysts , 1999 .

[25]  G. Jameson,et al.  Synthesis, Characterization, and Catalysis of β3-[(CoIIO4)W11O31(O2)4],10- the First Keggin-Based True Heteropoly Dioxygen (Peroxo) Anion. Spectroscopic (ESR, IR) Evidence for the Formation of Superoxo Polytungstates , 1999 .

[26]  M. Misono,et al.  Highly Efficient Utilization of Hydrogen Peroxide for Selective Oxygenation of Alkanes Catalyzed by Diiron-Substituted Polyoxometalate Precursor , 1998 .

[27]  Jincai Zhao,et al.  TiO2-assisted photodegradation of dye pollutants : II. Adsorption and degradation kinetics of eosin in TiO2 dispersions under visible light irradiation , 1998 .

[28]  C. Hill,et al.  Mechanism of Reaction of Reduced Polyoxometalates with O2 Evaluated by 17O NMR , 1997 .

[29]  C. Hill,et al.  Carbon powder and fiber-supported polyoxometalate catalytic materials. Preparation, characterization, and catalytic oxidation of dialkyl sulfides as mustard (HD) analogues , 1996 .

[30]  R. Neumann,et al.  The Manganese-Containing Polyoxometalate, [WZnMnII2(ZnW9O34)2]12-, as a Remarkably Effective Catalyst for Hydrogen Peroxide Mediated Oxidations , 1995 .

[31]  C. Hill,et al.  Role of Water in Polyoxometalate-Catalyzed Oxidations in Nonaqueous Media. Scope, Kinetics, and Mechanism of Oxidation of Thioether Mustard (HD) Analogs by tert-Butyl Hydroperoxide Catalyzed by H5PV2Mo10O40 , 1994 .

[32]  Y. Ishii,et al.  Oxidation of Phenols and Hydroquinones by Dioxygen Catalyzed by Mixed Addenda Heteropolyoxometalate on Active Carbon (NPV6Mo6/C) , 1994 .

[33]  R. Neumann,et al.  Highly Active Manganese-Containing Polyoxometalate as Catalyst for Epoxidation of Alkenes with Hydrogen Peroxide , 1994 .

[34]  R. Neumann,et al.  Aerobic oxidative dehydrogenations catalyzed by the mixed-addenda heteropolyanion PV2Mo10O405- : a kinetic and mechanistic study , 1992 .

[35]  C. Hill,et al.  Comparative Study of Polyoxometalates and Semiconductor Metal Oxides as Catalysts. Photochemical Oxidative Degradation of Thioethers. , 1991 .

[36]  R. Neumann,et al.  Selective aerobic oxidative dehydrogenation of alcohols and amines catalyzed by a supported molybdenum-vanadium heteropolyanion salt Na5PMo2V2O40 , 1991 .

[37]  H. Yamada,et al.  Hydrogen peroxide oxidation catalyzed by heteropoly acids combined with cetylpyridinium chloride. Epoxidation of olefins and allylic alcohols, ketonization of alcohols and diols, and oxidative cleavage of 1,2-diols and olefins , 1988 .

[38]  D. T. Sawyer,et al.  How super is superoxide , 1981 .

[39]  Y. Izumi,et al.  Catalysis of heteropoly acids entrapped in activated carbon. , 1981 .

[40]  E. Finkelstein,et al.  Spin trapping. Kinetics of the reaction of superoxide and hydroxyl radicals with nitrones , 1980 .

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

[42]  C. Hill,et al.  [(Fe(III)(OH(2))(2))(3)(A-alpha-PW(9)O(34))(2)](9-) on cationic silica nanoparticles, a new type of material and efficient heterogeneous catalyst for aerobic oxidations. , 2003, Journal of the American Chemical Society.

[43]  A. Hiskia,et al.  Photocatalytic reduction and recovery of copper by polyoxometalates. , 2002, Environmental science & technology.

[44]  E. Wang,et al.  Synthesis of new types of polyoxometallate pillared anionic clays: 31P and 27Al MAS NMR study of the orientation of intercalated PW11VO404– , 1996 .

[45]  C. Hill,et al.  Mechanism and Dynamics in the H3[PW12O40]-Catalyzed Selective Epoxidation of Terminal Olefins by H2O2. Formation, Reactivity, and Stability of {PO4[WO(O2)2]4}3- , 1995 .

[46]  A. Hiskia,et al.  Photocatalytic oxidation of organic compounds by polyoxometalates of molybdenum and tungsten : catalyst regeneration by dioxygen , 1992 .

[47]  Achim Müller,et al.  Polyoxometalate Chemistry: An Old Field with New Dimensions in Several Disciplines , 1991 .

[48]  R. Thouvenot,et al.  Vibrational investigations of polyoxometalates. 2. Evidence for anion-anion interactions in molybdenum(VI) and tungsten(VI) compounds related to the Keggin structure , 1983 .