组内消息
2017-02-06
Highlights:SOA formation is greatly enhanced with liquid NaCl droplets.
Abstract:Secondary organic aerosol (SOA) formation from the gas-phase ozonolysis of ethylene without irradiation was studied at different levels of relative humidity (RH) in both absence and presence of sodium chloride (NaCl) in a Teflon bag reactor. Results show that a small amount of SOA was formed from the ethylene ozonolysis in the absence of NaCl. When NaCl was in the form of liquid droplets, much more SOA could be formed. With the initial concentrations of 1 ppm and 0.5 ppm for ethylene and ozone, SOA concentrations of 3.0 to 8.6 μg/m3 were obtained after 5-h reactions under RH levels of 62% to 88% in the presence of NaCl seed particles, which were about 3~9 times higher than the results from the experiments without NaCl. The yield of SOA also increased with increasing RH, with the value being 3.0% at 88% RH in the presence of NaCl. Addition of the scavenger of OH radicals (n-hexane, ~900ppm) into the reaction system at 86% RH resulted in the decrease of the SOA yield by 21%. The liquid water content in aerosols was a key factor to SOA formation in the presence of different seed particles, including NaCl and Na2SO4. An analysis of the SOA with a Fourier-transform (FT) IR spectrometer shows that the particles formed from the ethylene ozonolysis were organic compounds that contained the functional groups of O–H, C=O, C–O, C–Cl and C–OH. The heterogeneous aqueous reaction is probably an effective pathway to form SOA from the ethylene ozonolysis, which should be considered in the atmosphere.
Ge Shuangshuang, Xu Yongfu, Jia Long, Secondary organic aerosol formation from ethylene ozonolysis in the presence of sodium chloride, Journal of Aerosol Science, doi:10.1016/j.jaerosci.2017.01.009.
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组内消息
2016-06-12
Effect of particle water on ozone and secondary organic aerosol formation from benzene-NO2-NaCl irradiations
(颗粒水对苯光氧化生成臭氧和二次有机气溶胶的影响规律)
Highlights
Liquid water content (LWC) can affect the ability in forming O3 and SOA from benzene.
Heterogeneous reaction of N2O5 with H2O(aq) is the major reason for the decrease of O3.
Hydrates from glyoxal were the major contributors to SOA under high LWC conditions.
Wang, Y.; Luo, H.; Jia, L.*; Ge, S. Effect of particle water on ozone and secondary organic aerosol formation from benzene-NO2-NaCl irradiations. Atmos. Environ. 2016, 140, 386–394.
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组内消息
2016-02-14
High light：Ethyne is the lightest of the non-methane hydrocarbons, whose oxidation product, glyoxal, is an important precursor of secondary organic aerosol. This study explores the effects of relative humidity on the formation of secondary organic aerosol under irradiation in the presence of nitrogen oxides and sodium chloride. Results show that relative humidity can enhance aerosol formation, which provides evidence of the contribution of ethyne to organic particles.
FTIR spectra of SOA from ethyne
The heterogeneous photochemical oxidation of ethyne was investigated under different relative humidity (RH) conditions in the presence of nitrogen oxides and sodium chloride in a self-made indoor smog chamber. The purpose was to study the influence of RH on the formation of secondary organic aerosol (SOA) from C2H2. Through the experiments, we found that SOA was rarely formed at <22% RH in the presence of NaCl seed particles, and that SOA began to be formed at ≥29 % RH in the presence of NaCl, which shows the importance of RH in the formation of SOA. The yield of SOA (YSOA) from C2H2 was 0.2 % at 51 % RH, and increased by a factor of 17.5 as RH reached 83%. The SOA yield increased with increasing RH. The geometric mean diameter of the particles increased by a factor of 1.17, 1.22, 1.28 and 1.51 at a RH of 51, 63, 74 and 83% respectively at the end of the experiment, indicating that the growth of the particle size also increased with increasing RH. Analysis of the SOA with Fourier-transform infrared (FTIR) spectrometry indicated that the particles generated from C2H2 contained the functional groups –OH, C=O, C–O–C and C–C–OH, for whose absorption peaks increase with increasing RH.
Ge Shuangshuang, Xu Yongfu, Jia Long (2016) Secondary organic aerosol formation from ethyne in the presence of NaCl in a smog chamber. Environmental Chemistry 13, 699-710.
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