title: OH-Initiated Oxidation of m-Xylene on Black Carbon Aging.
abstract: Laboratory experiments are conducted to investigate aging of size-classified black carbon (BC) particles from OH-initiated oxidation of m-xylene. The variations in the particle size, mass, effective density, morphology, optical properties, hygroscopicity, and activation as cloud condensation nuclei (CCN) are simultaneously measured by a suite of aerosol instruments, when BC particles are exposed to the oxidation products of the OH-m-xylene reactions. The BC aging is governed by the coating thickness (Δrve), which is correlated to the reaction time and initial concentrations of m-xylene and NOx. For an initial diameter of 100 nm and Δrve = 44 nm, the particle size and mass increase by a factor of 1.5 and 10.4, respectively, and the effective density increases from 0.43 to 1.45 g cm(-3) due to organic coating and collapsing of the BC core. The BC particles are fully converted from a highly fractal to nearly spherical morphology for Δrve = 30 nm. The scattering, absorption, and single scattering albedo of BC particles are enhanced accordingly with organic coating. The critical supersaturation for CCN activation is reduced to 0.1% with Δrve = 44 nm. The results imply that the oxidation of m-xylene exhibits larger impacts in modifying the BC particle properties than those for the OH-initiated oxidation of isoprene and toluene.
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing, 100871, China.
authors.forename: Song
authors.initials: S
authors.lastname: Guo
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing, 100871, China.
authors.forename: Min
authors.initials: M
authors.lastname: Hu
authors.affiliation: Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Yun
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Mario
authors.initials: M
authors.lastname: Gomez-Hernandez
authors.affiliation: Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Misti L
authors.initials: ML
authors.lastname: Zamora
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing, 100871, China.
authors.forename: Jianfei
authors.initials: J
authors.lastname: Peng
authors.affiliation: Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Collins
authors.affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing, 100871, China.|Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States.|Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Renyi
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000336:Aerosols; D002244:Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D053260:Soot / Q000737:chemistry*; D014992:Xylenes / Q000737:chemistry*
chemical_list: D000336:Aerosols; D053260:Soot; D014992:Xylenes; D002244:Carbon