Formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) from oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB)

Song Hou, Mohammednoor Altarawneh, Eric M. Kennedy, John C. Mackie, Roland Weber, Bogdan Z. Dlugogorski

Research output: Contribution to journalArticleResearchpeer-review

Abstract

This study investigates the formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB) under gas phase conditions over a temperature range of 400-800°C. The experiments involved an isothermal flow reactor equipped with a sample collection system to adsorb PCDD/F. We coated the walls of the reactor, made of high purity quartz, with boric oxide to remove catalytic effects and employed the gas chromatography-ion trap mass spectrometry (GC-ITMS) to quantitate PCDD/F. Trace analysis by GC-ITMS identified all four MCDF and up to five DCDF isomers, of which 3,7-DCDF constitutes the dominant species, formed directly from 4,4′-DCB. MCDD and DCDD appeared at lower concentration, generated from condensation of chlorophenoxy and chlorobenzenes. Our results show significant differences from the measurements of the thermal decomposition of polychlorinated biphenyls (PCB) performed in sealed ampoules, indicating strong surface effects present in earlier studies. Gas-phase reactions (> 600°C) lead to selective formation of a small number of lower-chlorinated pollutants, whereas reactive surfaces, as evident from literature, engender catalytic (but non-selective) appearance of a large number of higher-chlorinated and toxic chloroaryl congeners, even at temperature of less than 300°C. Results from the density functional theory (DFT) calculations indicate that, majority of the detected congeners of PCDF arise from the oxidative transformation of the parent 4,4′-DCB; i.e., not from the commonly suggested precursors of chlorinated phenols and benzenes. Our findings have significant importance to understanding the emission of PCB and PCDD/F in combustion processes.

Original languageEnglish
Pages (from-to)1075-1082
Number of pages8
JournalProceedings of the Combustion Institute
Volume37
Issue number1
Early online date28 Jun 2018
DOIs
Publication statusPublished - 2019
Externally publishedYes

Fingerprint

congeners
polychlorinated biphenyls
Polychlorinated Biphenyls
gas chromatography
Polychlorinated biphenyls
Gas chromatography
Mass spectrometry
Chlorobenzenes
mass spectroscopy
Gases
reactors
Ions
isothermal flow
vapor phases
Trace analysis
Oxidation
oxidation
Quartz
ampoules
chlorobenzenes

Cite this

Hou, Song ; Altarawneh, Mohammednoor ; Kennedy, Eric M. ; Mackie, John C. ; Weber, Roland ; Dlugogorski, Bogdan Z. / Formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) from oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB). In: Proceedings of the Combustion Institute. 2019 ; Vol. 37, No. 1. pp. 1075-1082.
@article{a55aa0773c054899a80c41c4e41efbd6,
title = "Formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) from oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB)",
abstract = "This study investigates the formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB) under gas phase conditions over a temperature range of 400-800°C. The experiments involved an isothermal flow reactor equipped with a sample collection system to adsorb PCDD/F. We coated the walls of the reactor, made of high purity quartz, with boric oxide to remove catalytic effects and employed the gas chromatography-ion trap mass spectrometry (GC-ITMS) to quantitate PCDD/F. Trace analysis by GC-ITMS identified all four MCDF and up to five DCDF isomers, of which 3,7-DCDF constitutes the dominant species, formed directly from 4,4′-DCB. MCDD and DCDD appeared at lower concentration, generated from condensation of chlorophenoxy and chlorobenzenes. Our results show significant differences from the measurements of the thermal decomposition of polychlorinated biphenyls (PCB) performed in sealed ampoules, indicating strong surface effects present in earlier studies. Gas-phase reactions (> 600°C) lead to selective formation of a small number of lower-chlorinated pollutants, whereas reactive surfaces, as evident from literature, engender catalytic (but non-selective) appearance of a large number of higher-chlorinated and toxic chloroaryl congeners, even at temperature of less than 300°C. Results from the density functional theory (DFT) calculations indicate that, majority of the detected congeners of PCDF arise from the oxidative transformation of the parent 4,4′-DCB; i.e., not from the commonly suggested precursors of chlorinated phenols and benzenes. Our findings have significant importance to understanding the emission of PCB and PCDD/F in combustion processes.",
keywords = "Halogenated biphenyls, Halogenated dibenzofurans and dibenzo-p-dioxins, Mechanism of formation of PCDD/F from PCB",
author = "Song Hou and Mohammednoor Altarawneh and Kennedy, {Eric M.} and Mackie, {John C.} and Roland Weber and Dlugogorski, {Bogdan Z.}",
year = "2019",
doi = "10.1016/j.proci.2018.05.045",
language = "English",
volume = "37",
pages = "1075--1082",
journal = "Proceedings of the Combustion Institute",
issn = "0082-0784",
publisher = "Elsevier",
number = "1",

}

Formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) from oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB). / Hou, Song; Altarawneh, Mohammednoor; Kennedy, Eric M.; Mackie, John C.; Weber, Roland; Dlugogorski, Bogdan Z.

In: Proceedings of the Combustion Institute, Vol. 37, No. 1, 2019, p. 1075-1082.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) from oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB)

AU - Hou, Song

AU - Altarawneh, Mohammednoor

AU - Kennedy, Eric M.

AU - Mackie, John C.

AU - Weber, Roland

AU - Dlugogorski, Bogdan Z.

PY - 2019

Y1 - 2019

N2 - This study investigates the formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB) under gas phase conditions over a temperature range of 400-800°C. The experiments involved an isothermal flow reactor equipped with a sample collection system to adsorb PCDD/F. We coated the walls of the reactor, made of high purity quartz, with boric oxide to remove catalytic effects and employed the gas chromatography-ion trap mass spectrometry (GC-ITMS) to quantitate PCDD/F. Trace analysis by GC-ITMS identified all four MCDF and up to five DCDF isomers, of which 3,7-DCDF constitutes the dominant species, formed directly from 4,4′-DCB. MCDD and DCDD appeared at lower concentration, generated from condensation of chlorophenoxy and chlorobenzenes. Our results show significant differences from the measurements of the thermal decomposition of polychlorinated biphenyls (PCB) performed in sealed ampoules, indicating strong surface effects present in earlier studies. Gas-phase reactions (> 600°C) lead to selective formation of a small number of lower-chlorinated pollutants, whereas reactive surfaces, as evident from literature, engender catalytic (but non-selective) appearance of a large number of higher-chlorinated and toxic chloroaryl congeners, even at temperature of less than 300°C. Results from the density functional theory (DFT) calculations indicate that, majority of the detected congeners of PCDF arise from the oxidative transformation of the parent 4,4′-DCB; i.e., not from the commonly suggested precursors of chlorinated phenols and benzenes. Our findings have significant importance to understanding the emission of PCB and PCDD/F in combustion processes.

AB - This study investigates the formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in oxidation of 4,4′-dichlorobiphenyl (4,4′-DCB) under gas phase conditions over a temperature range of 400-800°C. The experiments involved an isothermal flow reactor equipped with a sample collection system to adsorb PCDD/F. We coated the walls of the reactor, made of high purity quartz, with boric oxide to remove catalytic effects and employed the gas chromatography-ion trap mass spectrometry (GC-ITMS) to quantitate PCDD/F. Trace analysis by GC-ITMS identified all four MCDF and up to five DCDF isomers, of which 3,7-DCDF constitutes the dominant species, formed directly from 4,4′-DCB. MCDD and DCDD appeared at lower concentration, generated from condensation of chlorophenoxy and chlorobenzenes. Our results show significant differences from the measurements of the thermal decomposition of polychlorinated biphenyls (PCB) performed in sealed ampoules, indicating strong surface effects present in earlier studies. Gas-phase reactions (> 600°C) lead to selective formation of a small number of lower-chlorinated pollutants, whereas reactive surfaces, as evident from literature, engender catalytic (but non-selective) appearance of a large number of higher-chlorinated and toxic chloroaryl congeners, even at temperature of less than 300°C. Results from the density functional theory (DFT) calculations indicate that, majority of the detected congeners of PCDF arise from the oxidative transformation of the parent 4,4′-DCB; i.e., not from the commonly suggested precursors of chlorinated phenols and benzenes. Our findings have significant importance to understanding the emission of PCB and PCDD/F in combustion processes.

KW - Halogenated biphenyls

KW - Halogenated dibenzofurans and dibenzo-p-dioxins

KW - Mechanism of formation of PCDD/F from PCB

UR - http://www.scopus.com/inward/record.url?scp=85049007922&partnerID=8YFLogxK

U2 - 10.1016/j.proci.2018.05.045

DO - 10.1016/j.proci.2018.05.045

M3 - Article

VL - 37

SP - 1075

EP - 1082

JO - Proceedings of the Combustion Institute

JF - Proceedings of the Combustion Institute

SN - 0082-0784

IS - 1

ER -