Secondary Organic Aerosol Formation during the Photooxidation of Toluene: NOxDependence of Chemical Composition
Citations Over TimeTop 10% of 2007 papers
Abstract
The photooxidation of toluene is a potential source of secondary organic aerosol (SOA) in urban air, but only a small portion of the compounds present in SOA have been identified. In this study, we analyzed the chemical compositions of SOA produced by photoirradiation of the toluene/NOx/air system in laboratory chamber experiments by a combination of liquid chromatography-mass spectrometry, hybrid high-performance liquid chromatography-mass spectrometry, and iodometry-spectrophotometry. The dependence of the chemical composition on the initial NOx concentration was examined at initial NO concentrations ([NO]0) of 0.2 and 1 ppmv. Fifteen semivolatile products, including aromatic and ring-cleavage compounds, were quantified. However, the quantified products comprised only a small portion ( approximately 1 wt %) of the total aerosol mass. The total SOA yield ( approximately 13 wt %), the ratio of organic peroxides to total SOA mass ( approximately 17 wt %), and the density of SOA ( approximately 1.4 g cm-3) were independent of the NOx level, suggesting that the reaction mechanisms of the formation of major SOA products at [NO]0 = 0.2 and 1 ppmv are essentially the same. The negative-ion mass spectra of SOA samples showed that ion signals attributed to hemiacetal oligomers and/or decomposition products of peroxy hemiacetal oligomers were detected in the range of mass-to-charge ratios (m/z) between 200 and 500. The highest signals were detected at m/z = 155 and 177, and these were tentatively assigned to C7 unsaturated oxacyclic oxocarboxylic acids and C7 unsaturated oxacyclic dicarboxylic acids, respectively. We conclude that the major chemical components of the aerosol are hemiacetal and peroxy hemiacetal oligomers and low-molecular-weight dicarboxylic acids.
Related Papers
- → Relationship between Oxidation of Hydrocarbons and Reduction of NOx in Catalytic Removal of NOx.(1993)1 cited
- → SOx Poisoning on Rh Catalysts for NOx Selective Reduction.(2000)1 cited
- → Multi-scale Modeling and Study of Aerosol Growth on Amine-Based CO<sub>2</sub> Capture Absorber(2020)1 cited
- → Three-Dimensional Air Quality Simulation in the Osaka Bay Area in Typical Summer Day. (2). Ox-NOx-RH Reaction Mechanisms in Low- and High-NOx Regimes.(2003)
- Lab-scale 유동층 반응기에서 NOx 발생과 석탄 및 공기 공급과의 상관 관계에 대한 실험적 연구(2020)