Mechanisms of dioxin formation from the high-temperature pyrolysis of 2-bromophenol.

doi:10.1021/ES034387S

Paper

Mechanisms of dioxin formation from the high-temperature pyrolysis of 2-bromophenol.

Published Oct 22, 2003 · Catherine S Evans, B. Dellinger

Environmental science & technology

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89

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6

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Abstract

Brominated hydrocarbons are the most commonly used flame retardants. Materials containing brominated hydrocarbons are frequently disposed in municipal and hazardous waste incinerators as well as being subjected to thermal reaction in accidental fires. This results in the potential for formation of brominated dioxins and other hazardous combustion byproducts. In contrast to chlorinated hydrocarbons, the reactions of brominated hydrocarbons have been studied only minimally. As a model brominated hydrocarbon that may form brominated dioxins, we studied the homogeneous, gas-phase pyrolytic thermal degradation of 2-bromophenol in a 1-cm i.d., fused-silica flow reactor at a concentration of 90 ppm, with a reaction time of 2.0 s, and over a temperature range of 300 to 1000 degrees C. Observed products included dibenzo-p-dioxin (DD), 1-monobromodibenzo-p-dioxin (1-MBDD), 4-monobromodibenzofuran (4-MBDF), dibenzofuran (DF), naphthalene, bromonaphthalene, 2,4- and 2,6-dibromophenol, phenol, bromobenzene, and benzene. These results are compared and contrasted with previous results reported for 2-chlorophenol. At temperatures lower than 700 degrees C, formation of 2-bromophenoxyl radical, which decomposes through CO elimination to form a bromocyclopentadienyl radical, forms naphthalene and 2-bromonaphthalene through radical recombination/rearrangement reactions. However, unlike the results for 2-chlorophenol, where naphthalene is the major product, DD becomes the major product for the pyrolysis of 2-bromophenol. The formation of DD and 1-MBDD are attributed to radical-radical reactions involving 2-bromophenoxyl radical with the carbon- (bromine) centered radical and the carbon- (hydrogen) centered radical mesomers of 2-bromophenoxyl radical, respectively. The potential product, 4,6-dibromodibenzofuran (4,6-DBDF) for which the analogous product, 4,6-dichlorodibenzofuran (4,6 DCDF), was observed in the oxidation of 2-chlorophenol, was not detected. This is attributed to the pyrolytic conditions of our experiments (e.g., shorter reaction times and higher temperatures) that favor reaction intermediates that form DD and 1-MBDD.

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Study Snapshot

High-temperature pyrolysis of 2-bromophenol produces dibenzo-p-dioxin as the major product, with naphthalene as a minor product, due to shorter reaction times and higher temperatures.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Paper

Mechanisms of dioxin formation from the high-temperature pyrolysis of 2-bromophenol.

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References

Citations

Co-pyrolytic interactions and products of brominated epoxy resin and polyethylene terephthalate: TG-FTIR analysis and machine learning prediction

Co-pyrolysis of brominated epoxy resin and polyethylene terephthalate can produce CO2, benzoic acid, and alcohols, with potential environmental benefits and machine learning algorithms accurately predicting real-time volatile emissions.

A mechanistic and kinetic investigation on the oxidative thermal decomposition of decabromodiphenyl ether.

The oxidative thermal decomposition of BDE-209 leads to the formation of several hazardous pollutants, including octabrominated dibenzo-p-dioxin and furan, and can be controlled through various methods.

Framework of the Integrated Approach to Formation Mechanisms of Typical Combustion Byproducts─Polyhalogenated Dibenzo-p-dioxins/Dibenzofurans (PXDD/Fs).

This study developed a framework for identifying detailed PXDD/Fs formation mechanisms, using laboratory studies, theoretical calculations, and field studies, to aid in developing strategies for controlling POPs emissions.

Detoxification, solidification and recycling of municipal solid waste incineration fly ash: A review

Low-temperature catalytic pyrolysis with electrolytic manganese residue and solidification/stabilization combined processes can effectively degrade dioxins and enrich heavy metals in municipal solid waste incineration fly ash.

Formation of Environmentally Persistent Free Radicals during Thermochemical Processes and their Correlations with Unintentional Persistent Organic Pollutants.

EPFRs play a crucial role in the formation of toxic unintentionally produced persistent organic pollutants during thermal processes, highlighting the need for synergistic control strategies.

Photoinduced formation of persistent free radicals, hydrogen radicals, and hydroxyl radicals from catechol on atmospheric particulate matter

Catechol can produce environmentally persistent free radicals, with CaO, CuO, and Fe 2 O 3 significantly promoting their formation, potentially causing adverse effects on human health.

Evidence for multiple removal pathways in low-temperature (200-400 °C) thermal treatment of pentachlorophenol-laden soils.

Low-temperature thermal treatment of pentachlorophenol-laden soils primarily relies on OH-addition and dechlorination, with OH-addition increasing with temperature and dechlorination decreasing.

EPR detection of key radicals during coking process of lignin monomer pyrolysis

Controlling key free radicals during lignin monomer pyrolysis can suppress coke formation and improve conversion efficiency.

Mechanisms of dioxin formation from the high-temperature pyrolysis of 2-bromophenol.

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References

Citations

Co-pyrolytic interactions and products of brominated epoxy resin and polyethylene terephthalate: TG-FTIR analysis and machine learning prediction

Co-pyrolysis of brominated epoxy resin and polyethylene terephthalate can produce CO2, benzoic acid, and alcohols, with potential environmental benefits and machine learning algorithms accurately predicting real-time volatile emissions.

A mechanistic and kinetic investigation on the oxidative thermal decomposition of decabromodiphenyl ether.

The oxidative thermal decomposition of BDE-209 leads to the formation of several hazardous pollutants, including octabrominated dibenzo-p-dioxin and furan, and can be controlled through various methods.

Framework of the Integrated Approach to Formation Mechanisms of Typical Combustion Byproducts─Polyhalogenated Dibenzo-p-dioxins/Dibenzofurans (PXDD/Fs).

This study developed a framework for identifying detailed PXDD/Fs formation mechanisms, using laboratory studies, theoretical calculations, and field studies, to aid in developing strategies for controlling POPs emissions.

Detoxification, solidification and recycling of municipal solid waste incineration fly ash: A review

Low-temperature catalytic pyrolysis with electrolytic manganese residue and solidification/stabilization combined processes can effectively degrade dioxins and enrich heavy metals in municipal solid waste incineration fly ash.

Formation of Environmentally Persistent Free Radicals during Thermochemical Processes and their Correlations with Unintentional Persistent Organic Pollutants.

EPFRs play a crucial role in the formation of toxic unintentionally produced persistent organic pollutants during thermal processes, highlighting the need for synergistic control strategies.

Photoinduced formation of persistent free radicals, hydrogen radicals, and hydroxyl radicals from catechol on atmospheric particulate matter

Catechol can produce environmentally persistent free radicals, with CaO, CuO, and Fe 2 O 3 significantly promoting their formation, potentially causing adverse effects on human health.

Evidence for multiple removal pathways in low-temperature (200-400 °C) thermal treatment of pentachlorophenol-laden soils.

Low-temperature thermal treatment of pentachlorophenol-laden soils primarily relies on OH-addition and dechlorination, with OH-addition increasing with temperature and dechlorination decreasing.

EPR detection of key radicals during coking process of lignin monomer pyrolysis

Controlling key free radicals during lignin monomer pyrolysis can suppress coke formation and improve conversion efficiency.

Evidence for multiple removal pathways in low-temperature (200-400 °C) thermal treatment of pentachlorophenol-laden soils.