Experimental and theoretical studies on gas-phase reactions of NO3 radicals with three methoxyphenols: Guaiacol, creosol, and syringol. (January 2016)

• Record Type: Journal Article
• Authors: Yang, Bo; Zhang, Haixu; Wang, Youfeng; Zhang, Peng; Shu, Jinian; Sun, Wanqi; Ma, Pengkun
• Is Part Of: Atmospheric environment. Volume 125:Part A(2016)
• Page Start: 243
• Page End: 251
• Publication Date: 2016-01
• Subjects: Methoxyphenol -- NO3 radical -- Rate constant -- Reaction mechanism; DFT density functional theory -- IRC intrinsic reaction coordinate -- POA primary organic aerosol -- SOA secondary organic aerosol -- VUV-GTOFMS vacuum ultraviolet photoionization gas time-of-flight mass spectrometer; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2015.11.028
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: Methoxyphenols, lignin pyrolysis products, are major biomass combustion components and are considered potential tracers for wood smoke emissions. Their atmospheric reactivity, however, has not been well characterized. Guaiacol, creosol, and syringol are three typical methoxyphenols generated in relatively high concentrations in fresh wood smoke. In this study, the gas-phase reactions of NO3 radicals with these methoxyphenols were investigated using a laboratory-built vacuum ultraviolet photoionization gas time-of-flight mass spectrometer (VUV-GTOFMS) and off-line GC-MS. By combining experimental and theoretical methods, 4-nitroguaiacol, 6-nitroguaiacol, and 4, 6-dinitroguaiacol were determined as the primary degradation products for guaiacol; similarly, 6-nitrocreosol and 3-nitrosyringol were identified for creosol and syringol, respectively. Using the relative rate method, rate constants at 298 K and 1 atm for the gas-phase reactions of guaiacol, creosol, and syringol with NO3 radicals were measured to be 3.2 × 10 −12, 2.4 × 10 −13, and 4.0 × 10 −13 cm 3 molecule −1 s −1, respectively. At a typical tropospheric concentration of NO3 radicals (5 × 10 8 molecule cm −3 ), atmospheric lifetimes for guaiacol, creosol, and syringol toward NO3 radicals were 0.2, 2.3, and 1.4 h, respectively. These results indicate that the reaction with NO3 radicals can be a major sink for methoxyphenols at night. Highlights: Reaction products of NO3 radical with three methoxyphenols are obtained. Nitro-substituted derivatives are observed as major transformation products. Reaction mechanisms of methoxyphenols with NO3 radicals are proposed. The rate constants of three methoxyphenols with NO3 radicals are measured.