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4-Nitrophenol

The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform

Laisheng Li – 1st expert on this subject based on the ideXlab platform

  • Photocatalytic degradation of phenols in aqueous solution under irradiation of 254 and 185 nm UV light
    Catalysis Today, 2004
    Co-Authors: Wenya Han, Wanpeng Zhu, Pengyi Zhang, Ying Zhang, Laisheng Li

    Abstract:

    The photocatalytic decomposition and mineralization of 4-chlorophenol (4-CP), hydroquinone and 4-Nitrophenol (4-NP) in aqueous solution were investigated using two kinds of low-pressure mercury lamps: one was UV (ultraviolet) lamp emitting at 254nm and the other was VUV (vacuum ultraviolet) lamp emitting at both 254 and 185nm. VUV irradiation led to the most efficient degradation of the organics. Different mechanisms of photocatalysis and photolysis under VUV irradiation were observed. The degradation rate was subjected to the molecular structures of the substrates. 4-CP was easy to be decomposed, while hydroquinone was easy to be mineralized. However 4-NP was difficult to be decomposed or mineralized. VUV was efficient for decomposition of refractory compounds, such as nitrophenols, and the catalyst was efficient for TOC removal. © 2004 Elsevier B.V. All rights reserved.

  • Photocatalytic degradation of phenols in aqueous solution under irradiation of 254 and 185 nm UV light
    Catalysis Today, 2004
    Co-Authors: Wenya Han, Wanpeng Zhu, Pengyi Zhang, Ying Zhang, Laisheng Li

    Abstract:

    The photocatalytic decomposition and mineralization of 4-chlorophenol (4-CP), hydroquinone and 4-Nitrophenol (4-NP) in aqueous solution were investigated using two kinds of low-pressure mercury lamps: one was UV (ultraviolet) lamp emitting at 254 nm and the other was VUV (vacuum ultraviolet) lamp emitting at both 254 and 185 nm. VUV irradiation led to the most efficient degradation of the organics. Different mechanisms of photocatalysis and photolysis under VUV irradiation were observed. The degradation rate was subjected to the molecular structures of the substrates. 4-CP was easy to be decomposed, while hydroquinone was easy to be mineralized. However 4-NP was difficult to be decomposed or mineralized. VUV was efficient for decomposition of refractory compounds, such as nitrophenols, and the catalyst was efficient for TOC removal.

Igor V. Pletnev – 2nd expert on this subject based on the ideXlab platform

  • Solvent extraction and extraction-voltammetric determination of phenols using room temperature ionic liquid
    Analytical and Bioanalytical Chemistry, 2005
    Co-Authors: Kristine S. Khachatryan, Svetlana V. Smirnova, Irina I. Torocheshnikova, Natalia V. Shvedene, Andrey A. Formanovsky, Igor V. Pletnev

    Abstract:

    The phenolic compounds phenol, 4-Nitrophenol, 2,4-dinitrophenol, 2,6-dinitrophenol, 1-naphthol, 2-naphthol, and 4-chlorophenol are extracted nearly quantitatively from aqueous solution into the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6) in molecular form at pH < p Ka. Picric acid is extracted efficiently in anionic form. Recovery of pyrocatechol and resorcinol is much lower. The effect of pH, phenol concentration, and volume ratio of aqueous and organic phases were studied. Ionic liquid BMImPF6 is shown to be suitable for extraction-voltammetric determination of phenols without back-extraction or addition of support electrolyte. The electrochemical window of BMImPF6 at various electrodes was determined, and voltammetric oxidation of phenols and reduction of nitrophenols in BMImPF6 was studied.

Richard G. Compton – 3rd expert on this subject based on the ideXlab platform

  • Electrochemical reduction of nitrobenzene and 4-Nitrophenol in the room temperature ionic liquid [C4dmim][N(Tf)2]
    Journal of Electroanalytical Chemistry, 2006
    Co-Authors: Debbie S. Silvester, Andrew J. Wain, Leigh Aldous, Christopher Hardacre, Richard G. Compton

    Abstract:

    The reductions of nitrobenzene and 4-Nitrophenol were studied by cyclic voltammetry in the room temperature ionic liquid 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [C4dmim][N(Tf)2] on a gold microelectrode. Nitrobenzene was reduced reversibly by one electron and further by two electrons in a chemically irreversible step. The more complicated reduction of 4-Nitrophenol revealed three reductive peaks (two irreversible and one reversible) which were successfully simulated using the digital simulation program DigiSim®using a mechanism of rapid self-protonation, given below.(1)HOC6H4NO2+ e ⇋ HOC6H4NO2{radical dot} -(2){Mathematical expression}(3){Mathematical expression}(4)HOC6H4NO2H-+ HOC6H4NO2→ HOC6H4NO +-OC6H4NO2+ H2OTwo further anodic peaks were observed and were attributed to the oxidations of 4-hydroxyphenylhydroxylamine and 4-Nitrophenolate respectively. For both nitrobenzene and 4-Nitrophenol, diffusion coefficients were roughly two orders of magnitude smaller than in conventional solvents. It appears that both species are reduced following the same mechanisms as in conventional aprotic solvents, with differences in the voltammetry primarily due to the viscous nature of the ionic liquid. © 2006 Elsevier B.V. All rights reserved.

  • Studies of the electrochemical reduction of 4-Nitrophenol in dimethylformamide: evidence for a change in mechanism with temperature
    Physical Chemistry Chemical Physics, 2003
    Co-Authors: Claire L. Forryan, Richard G. Compton

    Abstract:

    The electrochemical reductions of 4-Nitrophenol, 2-cyanophenol and 4-cyanophenol were studied in dimethylformamide (DMF) at gold microdisk electrodes at elevated temperatures up to 110°C. It was inferred that there is a change in mechanism for the reduction of 4-Nitrophenol near 25°C. Over the entire temperature range 4-Nitrophenol is reduced to the corresponding radical anion, with subsequent rapid protonation by the parent molecule to form a radical species. At temperatures above 25°C it appears that this species can undergo further electrochemical reduction at the gold electrode, introducing a new voltammetric reduction wave, contrasting the response observed at platinum.