Photooxidation of selected polycyclic aromatic hydrocarbons and pyrenequinones coated on glass surfaces

Cope, Virgil W.; Kalkwarf, D.R.

doi:10.1021/es00161a004

Cited by 26 publications

(20 citation statements)

References 16 publications

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“…43 Pyrene has been shown to oxidize on glass surfaces upon exposure to ozone, producing pyrenequinones and other oxidation products; the ozonation rates for pyrene were observed to increase slightly with exposure to sunlight, but in the absence of oxygen, no photoreaction products of the PAH could be detected. 44 The role of silver in the observed interfacial reaction was also tested. Direct contact of pyrene with the metal is prevented 22 by a surface-polymerized silane layer, 23 and therefore it is assumed that the Ag should not affect the adsorption significantly.…”

Section: Resultsmentioning

confidence: 99%

C18-Modified Metal-Colloid Substrates for Surface-Enhanced Raman Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution

2004

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Metal colloids immobilized on a glass support substrate are modified with a self-assembled alkylsilane (C18) layer to promote adsorption of polycyclic aromatic hydrocarbons from aqueous solutions. Detection of these compounds from low concentration solutions is accomplished by using surface-enhanced Raman scattering (SERS). SERS spectra of pyrene adsorbed to C18-modified immobilized silver colloids are dominated by Raman bands that are not consistent with pyrene and indicate that pyrene undergoes a chemical reaction at the surface. The origins of this surface product are investigated, and it is determined that silver and oxygen are required to form the product, whose Raman spectrum is consistent with oxidation to a quinone. When a C18-modified gold-colloid substrate is used, Raman scattering consistent with unreacted pyrene is observed. The adsorption and detection of pyrene adsorbed from low (2 ppb) concentration aqueous solutions onto C18-modified gold-colloid substrates is reported; naphthalene and phenanthrene are detected at approximately 5 ppb. Adsorption kinetics are rapid (<5 min), and the concentration-dependent SERS response is consistent with a Langmuir isotherm.

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Section: Resultsmentioning

confidence: 99%

C18-Modified Metal-Colloid Substrates for Surface-Enhanced Raman Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution

2004

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“…In several previous studies results ranging from zero reactivity to half-lives on the order of 30-60 min at 200 ppb O 3 or ∼15 min at 1 ppm of O 3 have been reported, 1,4 and only in a few cases similarly high BaP decay rate coefficients were measured as in this work. [46][47][48][49] To explain the wide range of results mainly two potential reasons have been discussed: (a) surface/bulk shielding effects physically limiting the interaction of bulk molecules with gas-phase ozone and (b) chemical activation or passivation of BaP surface molecules by interaction with their substrate.…”

Section: Benzo[a]pyrene Degradation Kineticsmentioning

confidence: 99%

Interaction of Ozone and Water Vapor with Spark Discharge Soot Aerosol Particles Coated with Benzo[a]pyrene: O₃ and H₂O Adsorption, Benzo[a]pyrene Degradation, and Atmospheric Implications

et al. 2001

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The interaction of ozone and water vapor with spark discharge soot particles coated with the five-ring polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP) has been investigated in aerosol flow tube experiments at ambient temperature and pressure (296 K, 1 atm). The investigated range of ozone volume mixing ratio (VMR) and relative humidity (RH) was 0-1 ppm and 0-25%, respectively. The observed gas-phase ozone losses and pseudo-first-order BaP decay rate coefficients exhibited Langmuir-type dependencies on gas-phase ozone concentration and were reduced in the presence of water vapor, which indicates rapid, reversible and competitive adsorption of O 3 and H 2 O on the particles followed by a slower surface reaction between adsorbed O 3 and BaP. At low ozone VMR and RH, the half-life of surface BaP molecules was found to be shorter than previously reported (∼ 5 min at 30 ppb O 3 under dry conditions). At higher RH and for multilayer BaP surface coverage, however, a strong increase of BaP half-life was observed and can be attributed to competitive H 2 O adsorption and to surface/bulk shielding effects, respectively. From four independent sets of ozone loss and BaP decay measurement data the following parameters have been derived: O 3 and H 2 O Langmuir adsorption equilibrium constants K O 3 ) (2.8 ( 0.2) × 10 -13 cm 3 and K H 2 O ) (2.1 ( 0.4) × 10 -17 cm 3 , maximum pseudo-first-order BaP decay rate coefficient k 1,4 ) (0.015 ( 0.001) s -1 , adsorption site surface concentration [SS] S ) (5.7 ( 1.7) × 10 14 cm -2 . On the basis of these values, a second-order BaP-O 3 surface reaction rate coefficient k 2,s ) (2.6 ( 0.8) × 10 -17 cm 2 s -1 can be calculated, and estimates for the mean surface residence times and adsorption enthalpies of O 3 and H 2 O have been derived: τ O 3 ≈ 5-18 s; τ H 2 O ≈ 3 ms, ∆H ads,O 3 ≈ -(80-90) kJ mol -1 , ∆H ads,H 2 O ≈ -50 kJ mol -1 . The results and their atmospheric implications are discussed in view of related studies.

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“…Although in the literature, first-order rate expressions with respect to polyaromatic hydrocarbons (PAHs) have been reported for the reactions of ozone and PAHs in the aqueous phase (Butkovicet al, 1983) and gaseous ozone with solid PAHs on uniformly coated surfaces (Wu et al, 1984;Cope and Kalkwart, 1987;Alebic-Jurectic et al, 1990), the presence of two kinetic regions has not been reported. The two kinetic regimes observed in the systems used in this study may be due to variations in the contacting surface area between gaseous ozone and solid phenanthrene during the course of the reaction.…”

Section: Ozone With Phenanthrenementioning

confidence: 99%

The Kinetics of the Reaction of Ozone with Phenanthrene in Unsaturated Soils

Hsu¹,

Masten²

1997

Environmental Engineering Science

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The kinetics of the heterogeneous reactions of gaseous ozone with soil water, the soil matrix, and phenanthrene were investigated in a cycling batch reactor. The rate of ozone decomposition in soil water is described as a first-order rate expression with respect to the gaseous ozone concentration. The rate expression for the reaction of gaseous ozone with the soil matrix in moist soil can be described as second order overall, first order with respect to both gaseous ozone and soil organic matter concentrations. The rate of reaction for ozone with the soil matrix was observed to be independent of the ozone gas pore velocity (over the range of 0.18 to 23.4 cm/s), indicating that the overall reaction rate is dominated by chemical reactions rather than by interfacial mass transfer.During ozonation of a phenanthrene-contaminated soil, two pseudo-first-order kinetic regions with respect to the concentration of phenanthrene were observed. This is thought to be due to the nonuniformity of the surface distribution of solid phenanthrene, which may be present as material that is either floating on the soil water or is trapped in the soil pores.

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Photooxidation of selected polycyclic aromatic hydrocarbons and pyrenequinones coated on glass surfaces

Cited by 26 publications

References 16 publications

C18-Modified Metal-Colloid Substrates for Surface-Enhanced Raman Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution

C18-Modified Metal-Colloid Substrates for Surface-Enhanced Raman Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution

Interaction of Ozone and Water Vapor with Spark Discharge Soot Aerosol Particles Coated with Benzo[a]pyrene: O₃ and H₂O Adsorption, Benzo[a]pyrene Degradation, and Atmospheric Implications

The Kinetics of the Reaction of Ozone with Phenanthrene in Unsaturated Soils

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Photooxidation of selected polycyclic aromatic hydrocarbons and pyrenequinones coated on glass surfaces

Cited by 26 publications

References 16 publications

C18-Modified Metal-Colloid Substrates for Surface-Enhanced Raman Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution

C18-Modified Metal-Colloid Substrates for Surface-Enhanced Raman Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution

Interaction of Ozone and Water Vapor with Spark Discharge Soot Aerosol Particles Coated with Benzo[a]pyrene: O3 and H2O Adsorption, Benzo[a]pyrene Degradation, and Atmospheric Implications

The Kinetics of the Reaction of Ozone with Phenanthrene in Unsaturated Soils

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Interaction of Ozone and Water Vapor with Spark Discharge Soot Aerosol Particles Coated with Benzo[a]pyrene: O₃ and H₂O Adsorption, Benzo[a]pyrene Degradation, and Atmospheric Implications