Atmospheric oxidation of gaseous anthracene and phenanthrene initiated by OH radicals

Emission factors for polycyclic aromatic hydrocarbons from laboratory biomass-burning and their chemical transformations during aging in an oxidation flow reactor

“…We believe that direct reactions between gas-phase oxidants and particle-phase organic molecules are highly unlikely inside the OFR, because heterogeneous reactions with OH radicals are significantly (orders of magnitudes) slower than gas-phase reactions ( Kroll et al, 2015 ). We expect that these particle phenanthrenes, due to their semi-volatile nature, steadily evaporated as they reacted in the gas phase to form oxo/nitro-PAHs and other oxidized products ( Kwok et al, 1994 ; Zeng et al, 2020 ; Zhao et al, 2016 ). However, we also identified a potential artifact of our oxidation setup that in absence of an ozone scrubber in front of the tandem filter-XAD collection system, heterogeneous oxidation with ozone can take place on the filter surface ( Sengupta et al, 2020 ) and thus can potentially impact fate of PAHs.…”

Polycyclic Aromatic Hydrocarbons (PAHs) in Freshwater Systems: A Comprehensive Review of Sources, Distribution, and Impacts

“…Notably, when the water layer thickness exceeded 2.0 nm, it significantly reduced the adsorption capabilities of both quartz and LHA [267]. In another study conducted by Zeng et al [268] the oxidation of anthracene (ANT) and phenanthrene (PHE) initiated by OH radicals was explored using quantum chemistry and chemical kinetics. The process begins with PAH-OH adducts reacting with O2 and NO2, forming radical species that can either revert, isomerize to oxygenated PAHs (OPAHs), or react with NO.…”

Prediction of •OH-Initiated and •NO3-Initiated Transformation Products of Polycyclic Aromatic Hydrocarbons by Electronic Structure Approaches

“…Polycyclic aromatic hydrocarbons (PAHs) with high potential mutagenicity and carcinogenicity are the main byproducts in several incomplete combustion processes. − The persistent PAHs are spread into the atmosphere and deposited into soil and water, − which causes irreparable damage to human health and ecosystems. ,, Most scientific literature studies focus on the 16 priority PAHs defined by the United States Environmental Protection Agency (USEPA) . A significant amount of work − has reported on the abiotic reactions of PAHs with atmospheric oxidants of hydroxyl radicals ( • OH) and nitro radicals ( • NO 3 ) in the presence of O 2 and NO x . The dominant mechanism involves electrophilic addition of • OH and • NO 3 to the aromatic ring, which results in the formation of nitro-PAHs (NPAHs), hydroxyl-PAHs (OHPAHs), and oxy-PAHs (OPAHs). , However, the presence of numerous isomers and the absence of some standards prevented the laboratory to identify some new PAH transformation products (PAH-TPs) .…”