TY - JOUR
T1 - Low-temperature oxidation of monobromobenzene
T2 - Bromine transformation and yields of phenolic species
AU - Altarawneh, Mohammednoor
AU - Dlugogorski, Bogdan Z.
N1 - Funding Information:
This study has been supported by the 2019 Abu Dhabi Award for Research Excellence (AARE) – (Abu Dhabi Department of Education and Knowledge), grant ID: 21N225-AARE2019–ADEK-103. Computations were carried out at the high performance computing cluster at the United Arab Emirates Univerity (UAEU).
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/10
Y1 - 2021/10
N2 - Brominated benzenes and phenols constitute direct precursors in the formation of bromine-bearing pollutants; most notably PBDD/Fs and other dioxin-type compounds. Elucidating accurate mechanisms and constructing robust kinetic models for the oxidative transformation of bromobenzenes and bromophenols into notorious Br-toxicants entail a comprehensive understanding of their initial oxidation steps. However, pertinent mechanistic studies, based on quantum chemical calculations, have only focused on secondary condensation reactions into PBDD/Fs and PBDEs. Literature provide kinetic parameters for these significant reactions, nonetheless, without attempting to compile the acquired Arrhenius coefficients into kinetic models. To fill in this gap, this study sets out to illustrate primary chemical phenomena underpinning the low-temperature combustion of a monobromobenzene molecule (MBZ) based on a detail chemical kinetic model. The main aim is to map out temperature-dependent profiles for major intermediates and products. The constructed kinetic model encompasses several sub-mechanisms (i.e, HBr and benzene oxidation, bromination of phenoxy radicals, and initial reaction of oxygen molecules with MBZ). In light of germane experimental observations, the formulated kinetic model herein offers an insight into bromine speciation, conversion profile of MBZ, and formation of higher brominated congeners of benzene and phenol. For instance, the model satisfactorily accounts for the yields of dibromophenols from oxidation of a 2-bromophenol (2-MBP) molecule, in reference to analogous experimental measurements. From an environmental perspective, the model reflects the accumulation of appreciable loads of 2-bromophenoxy radicals at intermediate temperatures (i.e., a bromine-containing environmental persistent free radical, EPFR) from combustion of MBZ and 2-MBP molecules. Acquired mechanistic/kinetic parameters shall be useful in comprehending the complex bromine transformation chemistry in real scenarios, most notably those prevailing in thermal recycling of brominated flame retardants (BFRs).
AB - Brominated benzenes and phenols constitute direct precursors in the formation of bromine-bearing pollutants; most notably PBDD/Fs and other dioxin-type compounds. Elucidating accurate mechanisms and constructing robust kinetic models for the oxidative transformation of bromobenzenes and bromophenols into notorious Br-toxicants entail a comprehensive understanding of their initial oxidation steps. However, pertinent mechanistic studies, based on quantum chemical calculations, have only focused on secondary condensation reactions into PBDD/Fs and PBDEs. Literature provide kinetic parameters for these significant reactions, nonetheless, without attempting to compile the acquired Arrhenius coefficients into kinetic models. To fill in this gap, this study sets out to illustrate primary chemical phenomena underpinning the low-temperature combustion of a monobromobenzene molecule (MBZ) based on a detail chemical kinetic model. The main aim is to map out temperature-dependent profiles for major intermediates and products. The constructed kinetic model encompasses several sub-mechanisms (i.e, HBr and benzene oxidation, bromination of phenoxy radicals, and initial reaction of oxygen molecules with MBZ). In light of germane experimental observations, the formulated kinetic model herein offers an insight into bromine speciation, conversion profile of MBZ, and formation of higher brominated congeners of benzene and phenol. For instance, the model satisfactorily accounts for the yields of dibromophenols from oxidation of a 2-bromophenol (2-MBP) molecule, in reference to analogous experimental measurements. From an environmental perspective, the model reflects the accumulation of appreciable loads of 2-bromophenoxy radicals at intermediate temperatures (i.e., a bromine-containing environmental persistent free radical, EPFR) from combustion of MBZ and 2-MBP molecules. Acquired mechanistic/kinetic parameters shall be useful in comprehending the complex bromine transformation chemistry in real scenarios, most notably those prevailing in thermal recycling of brominated flame retardants (BFRs).
KW - Bromobenzene
KW - Combustion
KW - Kinetic model
KW - PBDD/Fs
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U2 - 10.1016/j.chemosphere.2021.130621
DO - 10.1016/j.chemosphere.2021.130621
M3 - Article
C2 - 33964746
AN - SCOPUS:85105348663
SN - 0045-6535
VL - 280
JO - Chemosphere
JF - Chemosphere
M1 - 130621
ER -