Studies on the photooxidation of methyl-substituted aromatic hydrocarbons have revealed that whereas electron density is a determinant of endoperoxide formation, steric factors are most important in influencing the stability of the endoperoxide. Additional information on the energetics of the reactions and on the magnitude of the steric interactions was obtained using calculations at the B3LYP/6-311+G* level of theory.
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ACS EST Air
April 2024
Department of Environmental Sciences, University of California, Riverside, Riverside, California 92521, United States.
The chemical and optical properties of secondary organic aerosols (SOA) have been widely studied through environmental chamber experiments, and some of the results have been parametrized in atmospheric models to help understand their radiative effects and climate influence. While most chamber studies investigate the aerosol formed from a single volatile organic compound (VOC), the potential interactions between reactive intermediates derived from VOC mixtures are not well understood. In this study, we investigated the SOA formed from pure and mixtures of anthropogenic (phenol and 1-methylnaphthalene) and/or biogenic (longifolene) VOCs using continuous-flow, high-NO photooxidation chamber experiments to better mimic ambient conditions.
View Article and Find Full Text PDFEnviron Sci Technol
February 2019
SKL-ESPC and BIC-ESAT, College of Environmental Sciences and Engineering , Peking University, Beijing 100871 , China.
Naphthalene (Nap) and methylnaphthalene (MN) are the most abundant polycyclic aromatic hydrocarbons (PAHs) in atmosphere and have been proposed to be important precursors of anthropogenic secondary organic aerosol (SOA) derived from laboratory chamber experiments. In this study, atmospheric Nap/MN and their gas-phase photooxidation products were quantified by a Proton Transfer Reaction-Quadrupole interface Time-of-Flight Mass Spectrometer (PTR-QiTOF) during the 2016 winter in Beijing. Phthalic anhydride, a late generation product from Nap under high-NO conditions, appeared to be more prominent than 2-formylcinnamaldehyde (early generation product), possibly due to more sufficient oxidation during the haze.
View Article and Find Full Text PDFEnviron Sci Technol
June 2015
†Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
In the present study, formation of aromatic organosulfates (OSs) from the photo-oxidation of polycyclic aromatic hydrocarbons (PAHs) was investigated. Naphthalene (NAP) and 2-methylnaphthalene (2-MeNAP), two of the most abundant gas-phase PAHs and thought to represent "missing" sources of urban SOA, were photochemically oxidized in an outdoor smog chamber facility in the presence of nonacidified and acidified sulfate seed aerosol. Effects of seed aerosol composition, acidity and relative humidity on OS formation were examined.
View Article and Find Full Text PDFEnviron Sci Technol
November 2010
Department of Civil and Environmental Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA.
Secondary organic aerosol (SOA) formation from the photooxidation of five polycyclic aromatic hydrocarbons (PAHs, naphthalene, 1- and 2-methylnaphthalene, acenaphthylene, and acenaphthene) was investigated in a 9-m(3) chamber in the presence of nitrogen oxides and the absence of seed aerosols. Aerosol size distributions and PAH decay were monitored by a scanning mobility particle sizer and a gas chromatograph with a flame ionization detector. Over a wide range of conditions, the aerosol yields for the investigated PAHs were observed to be in the range of 2-22%.
View Article and Find Full Text PDFEnviron Sci Technol
May 2007
Department of Environmental Chemistry, IIQAB-CSIC, Jordi Girona, 18-26, 08034 Barcelona, Spain.
More than 200 oil samples were collected along the Northern Spanish coast, from December 2002 to December 2003, as part of the extensive monitoring program carried out by the Spanish Marine Safety Agency after the Prestige heavy oil spill (November 13, 2002). The GC FPD/ FID and comprehensive GC x GC/TOFMS sample profiles revealed the main characteristics of the oil residues. Chemical fingerprinting of the aliphatic and aromatic fractions by GC/ MS was performed to determine the source of the oil as well as to follow its weathering at sea.
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