Mechanisms and kinetic studies of OH-initiated atmospheric oxidation of methoxyphenols in the presence of O2 and NOx

Sun, Yanhui; Xu, Fei; Li, Xiaofan; Zhang, Qingzhu; Gu, Yuanxiang

doi:10.1039/c9cp03246k

Cited by 25 publications

(40 citation statements)

References 32 publications

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“…Alternatively, carbon loss can also be explained by initial H-abstraction from the methoxy group followed by O 2 binding and the elimination of formaldehyde in the reductive NO atmosphere. 50 Neither of those byproducts, however, have been experimentally detected that the exact mechanism could have been unequivocally confirmed.…”

Section: Resultsmentioning

confidence: 99%

“…It has been suggested very recently by density functional theory (DFT) calculations that the [Ar–OH] • adduct with OH attached at position 2 is most favorable. 50 Another study showed that although it is theoretically feasible that OH binds to any aromatic C-atom in GUA, giving the corresponding isomeric [Ar–OH] • adducts and products, the OH attack to the hydroxyl-bearing carbon atom and to positions 2 and 4 are slightly more favorable as to the other C-atoms. 24 Moreover, our study shows that carbon loss is facilitated at high RH, which further implies the involvement of water molecules in the process of methoxy group release, possibly yielding methanol and the OH radical instead of the methoxy radical.…”

Section: Resultsmentioning

confidence: 99%

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Guaiacol Nitration in a Simulated Atmospheric Aerosol with an Emphasis on Atmospheric Nitrophenol Formation Mechanisms

Kroflič

Anders

Drventić

et al. 2021

ACS Earth Space Chem.

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Atmospheric nitrophenols are pollutants of concern due to their toxicity and light-absorption characteristics and their low reactivity resulting in relatively long residence times in the environment. We investigate multiphase nitrophenol formation from guaiacol in a simulated atmospheric aerosol and support observations with the corresponding chemical mechanisms. The maximal secondary organic aerosol (SOA) yield (42%) is obtained under illumination at 80% relative humidity. Among the identified nitrophenols, 4-nitrocatechol (3.6% yield) is the prevailing species in the particulate phase. The results point to the role of water in catechol and further 4-nitrocatechol formation from guaiacol. In addition, a new pathway of dark nitrophenol formation is suggested, which prevailed in dry air and roughly yielded 1% nitroguaiacols. Furthermore, the proposed mechanism possibly leads to oligomer formation via a phenoxy radical formation by oxidation with HONO.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Guaiacol Nitration in a Simulated Atmospheric Aerosol with an Emphasis on Atmospheric Nitrophenol Formation Mechanisms

Kroflič

Anders

Drventić

et al. 2021

ACS Earth Space Chem.

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“…Phenoxy radicals generally derive from OH reaction with phenolic molecules and both NO and O3 compete with NO2 for reaction with phenoxy radicals; products from reaction with NO and O3 are not well established (Vereecken, 2019). The importance of the OH-aromatic adduct + NO2 pathway to nitro-aromatic formation is suggested as small for species such as toluene and phenol owing to efficient reaction with O2 (Atkinson et al, 1992;Vereecken, 2019), although has been proposed as the major pathway for nitro-aromatic formation from guaiacol and similar species (Lauraguais et al, 2014;Sun et al, 2019).…”

Section: Chamber Photochemical Model Descriptionmentioning

confidence: 99%

Biomass-burning-derived particles from a wide variety of fuels: Part 2: Effects of photochemical aging on particle optical and chemical properties

Cappa¹,

Lim²,

Hagan³

et al. 2020

Preprint

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Abstract. Particles in smoke emitted from biomass combustion have a large impact on global climate and urban air quality. There is limited understanding of how particle optical properties &#8211; especially the contributions of black carbon (BC) and brown carbon (BrC) &#8211; evolve with photochemical aging of smoke. We analyze the evolution of the optical properties and chemical composition of particles produced from combustion of a wide variety of biomass fuels, largely from the Western U.S.. The smoke is photochemically aged in a reaction chamber over atmospheric-equivalent timescales ranging from 0.25&#8211;8&#8201;days. Various aerosol optical properties (e.g., the single scatter albedo, the wavelength dependence of absorption, and the BC mass absorption coefficient (MACBC)) evolved with photochemical aging, with the specific evolution dependent on the initial particle properties and conditions. The impact of coatings on BC absorption (the so-called lensing effect) was small, even after photochemical aging. The initial evolution of the BrC absorptivity (MACBrC) varied between individual burns, but decreased consistently at longer aging times; the wavelength-dependence of the BrC absorption generally increased with aging. The observed changes to BrC properties result from a combination of SOA production and heterogeneous oxidation of primary and secondary OA mass, with SOA production being the major driver of the changes. The SOA properties varied with time, reflecting both formation from precursors having a range of lifetimes with respect to OH and the evolving photochemical environment within the chamber. Although the absorptivity of BrC generally decreases with aging, the dilution-corrected absorption may actually increase from the production of SOA. These experimental results provide context for the interpretation of ambient observations of the evolution of particle optical properties in biomass combustion-derived smoke plumes.

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“…Laboratory measurements can help provide the mechanistic understanding necessary to comprehensively interpret the field observations. Most laboratory studies investigating photochemical aging effects on optical properties, and in particular light absorption, of BB particles have done so for only a small number of individual fuel types or burn conditions and often for particles alone rather than smoke (e.g., Saleh et al, 2013;Sumlin et al, 2017;Tasoglou et al, 2017;Wong et al, 2017;Kumar et al, 2018). Thus, while these studies have proven insightful, the limited number of fuels and conditions considered makes extending the observations to the atmosphere thus far challenging.…”

Section: Introductionmentioning

confidence: 99%

Biomass-burning-derived particles from a wide variety of fuels – Part 2: Effects of photochemical aging on particle optical and chemical properties

et al. 2020

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Abstract. Particles in smoke emitted from biomass combustion have a large impact on global climate and urban air quality. There is limited understanding of how particle optical properties – especially the contributions of black carbon (BC) and brown carbon (BrC) – evolve with photochemical aging of smoke. We analyze the evolution of the optical properties and chemical composition of particles produced from combustion of a wide variety of biomass fuels, largely from the western United States. The smoke is photochemically aged in a reaction chamber over atmospheric-equivalent timescales ranging from 0.25 to 8 d. Various aerosol optical properties (e.g., the single-scatter albedo, the wavelength dependence of absorption, and the BC mass absorption coefficient, MACBC) evolved with photochemical aging, with the specific evolution dependent on the initial particle properties and conditions. The impact of coatings on BC absorption (the so-called lensing effect) was small, even after photochemical aging. The initial evolution of the BrC absorptivity (MACBrC) varied between individual burns but decreased consistently at longer aging times; the wavelength dependence of the BrC absorption generally increased with aging. The observed changes to BrC properties result from a combination of secondary organic aerosol (SOA) production and heterogeneous oxidation of primary and secondary OA mass, with SOA production being the major driver of the changes. The SOA properties varied with time, reflecting both formation from precursors having a range of lifetimes with respect to OH and the evolving photochemical environment within the chamber. Although the absorptivity of BrC generally decreases with aging, the dilution-corrected absorption may actually increase from the production of SOA. These experimental results provide context for the interpretation of ambient observations of the evolution of particle optical properties in biomass-combustion-derived smoke plumes.

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Mechanisms and kinetic studies of OH-initiated atmospheric oxidation of methoxyphenols in the presence of O₂ and NO_x

Abstract: Methoxyphenols, as the main products and tracers of biomass burning, have been demonstrated to play an important role in the formation of secondary organic aerosols.

Cited by 25 publications

References 32 publications

Guaiacol Nitration in a Simulated Atmospheric Aerosol with an Emphasis on Atmospheric Nitrophenol Formation Mechanisms

Guaiacol Nitration in a Simulated Atmospheric Aerosol with an Emphasis on Atmospheric Nitrophenol Formation Mechanisms

Biomass-burning-derived particles from a wide variety of fuels: Part 2: Effects of photochemical aging on particle optical and chemical properties

Biomass-burning-derived particles from a wide variety of fuels – Part 2: Effects of photochemical aging on particle optical and chemical properties

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