Atmospheric chemistry of PCBs, PCDDs and PCDFs

Hester, R. E.; Harrison, Roy M.; Atkinson, Roger

doi:10.1039/9781847550491-00053

Cited by 32 publications

(45 citation statements)

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“…The differing results of these approaches have been attributed to the fact that DFT can describe the effects of intramolecular chlorine substitution between two benzene rings and intermolecular chlorine substitution within one benzene ring more effectively [224]. The effect of chlorine positions in lateral (2,3,7,8) and non-lateral (1,4,6,9) sites on the enthalpy of formation has also been investigated. Numerical estimates for these factors have been derived to establish empirical formulas for entropies and enthalpies of formation as a function of the number of chlorine substituents, their positions and their interactions with each other [223].…”

Section: Thermochemical Parameters and Their Influence On Pcdd/f Formmentioning

confidence: 98%

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Mechanisms for formation, chlorination, dechlorination and destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)

Altarawneh

Dlugogorski

Kennedy

et al. 2009

Progress in Energy and Combustion Science

429

279

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Section: Thermochemical Parameters and Their Influence On Pcdd/f Formmentioning

confidence: 98%

“…These involve combustion, municipal waste incineration (MWI), metal industries, bushfires and prescribed and uncontrolled burning [2,3]. Once emitted to the receiving environment, atmospheric transport moves them away from their emission sources to where they pollute water resources and enter the food chain [4].…”

Section: Introduction To Pcdd/fsmentioning

confidence: 99%

Mechanisms for formation, chlorination, dechlorination and destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)

Altarawneh

Dlugogorski

Kennedy

et al. 2009

Progress in Energy and Combustion Science

429

279

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“…13,15 It is well-known SCHEME 2: Mechanistic Diagram of the DF-OH(1) Reaction with Dioxygen where a negative temperature dependence has also been observed. The calculated rate constant is almost 20 times faster than that for benzene, 19,37 4 times faster than that of the toluene system, 38 only twice as fast as that of p-xylene, 23 and the same as that of phenol.…”

Section: Df-oh Adductsmentioning

confidence: 97%

Computational Study of the Oxidation and Decomposition of Dibenzofuran under Atmospheric Conditions

et al. 2008

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The atmospheric degradation of dibenzofuran (DF) initiated by OH addition has been studied by using density functional theory (B3LYP method). Site C1 in DF is predicted to be the favored site for OH addition, with a branching ratio of 0.61 to produce a DF-OH(1) adduct. The calculated reaction rate constant for OH addition to DF has been used to predict the atmospheric lifetime of DF to be 0.45 day. Three different modes of attack of O2 ((3)Sigma(g)) on DF-OH(1) have been examined. Abstraction of hydrogen gem to OH in DF-OH(1) by O2 ((3)Sigma(g)) (producing 1-dibenzofuranol I) and dioxygen addition in the three radical sites in cis and trans orientation (relative to the ispo-added OH) of the pi-delocalized electron system of DF-OH(1) are feasible under atmospheric conditions. The free energy of activation (at 298.15 K) for the formation of 1-dibenzofuranol is 15.1 kcal/mol with a free energy change of -36.3 kcal/mol, while the formation of DF-OH(1)-O2 adducts are endergonic by 9.2-21.8 kcal/mol with a 16.3-23.6 kcal/mol free energy of activation. On the basis of the calculated reaction rate constants, the formation of 1-dibenzofuranol is more important than the formation of DF-OH-O2 adducts. The results presented here are a first attempt to gain a better understanding of the atmospheric oxidation of dioxin-like compounds on a precise molecular basis.

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“…W t , J,φ and E are total washout ratio, precipitation rate, particleassociated fraction of the component, and emission rate from sources at ground level respectively. W t is related to W g and W p , the washout ratios of gas and particle phases, (Atkinson, 1996) by:…”

Section: Methodsmentioning

confidence: 99%

Transient and spatial modeling and simulation of polybrominated diphenyl ethers reaction and transport in air, water and soil

Mousavi

Kiani

Lotfi

et al. 2008

Int. J. Environ. Sci. Technol.

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ABSTRACT:The release of the wastes containing polybrominated diphenyl ethers into the environment is a worldwide major concern. Investigation of spatial and temporal variations of polybrominated diphenyl ethers concentrations due to different factors, especially the transport of these species between air and water as well as between air and soil is the purpose of present research. A model was developed and solved using the methods of finite difference and lines. Simulations were implemented for three dimensions of width, length, and height and also time for the air compartment, whereas for the soil and water compartments, variations were considered only with respect to height and time. Transport between water and soil was disregarded for simplicity at this stage. Vancouver's landfill was considered as a case study. Lower concentrations in air and higher concentrations in water at the interface show that these pollutants tend to diffuse from air to water. Concentrations of all four pollutants decrease near the interface in soil as time passes, but they are predicted to be almost constant at other levels.

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Atmospheric chemistry of PCBs, PCDDs and PCDFs

Cited by 32 publications

References 0 publications

Mechanisms for formation, chlorination, dechlorination and destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)

Mechanisms for formation, chlorination, dechlorination and destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)

Computational Study of the Oxidation and Decomposition of Dibenzofuran under Atmospheric Conditions

Transient and spatial modeling and simulation of polybrominated diphenyl ethers reaction and transport in air, water and soil

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