Water vapour influence over the PAN stability: Homogeneous and heterogeneous processes between PAN-NO2-H2O

Heterogeneous Reaction of Peroxyacetyl Nitrate on Real-World PM2.5 Aerosols: Kinetics, Influencing Factors, and Atmospheric Implications

“…As shown in Figure C, ALWC has a significant positive correlation with the γ ( p < 0.01, r = 0.52). Recent studies have reported that PAN molecules can be trapped by water clusters to form PAN-nH 2 O complexes, or accommodated on water surfaces, ,− indicating that PAN can undergo heterogeneous uptake from the gas phase through interaction with water in the aqueous film on aerosols. Figure D shows the significant negative correlation between ionic strength and γ ( p < 0.01, r = −0.43).…”

“…In this study, high-purity N 2 was used as the carrier gas for the three gas flows. O 2 was not added to the system, in order to reduce the PAN heterogeneous uptake uncertainties that can be affected by the varying PAN thermal decomposition induced by the balance of NO and NO 2 under different RH conditions when O 2 was involved . The total flow rate was maintained at 1 standard liter per minute (slm) to ensure laminar flow in the reactor (Reynolds number = 52) .…”

“…O 2 was not added to the system, in order to reduce the PAN heterogeneous uptake uncertainties that can be affected by the varying PAN thermal decomposition induced by the balance of NO and NO 2 under different RH conditions when O 2 was involved. 29 The total flow rate was maintained at 1 standard liter per minute (slm) to ensure laminar flow in the reactor (Reynolds number = 52). 32 For gas flow I, PAN standard gas was carried by N 2 at a flow rate of 0− 5 standard cubic centimeters per minute (sccm) controlled by MFC2.…”

“…Winter field measurement found that increasing PM 2.5 levels accompanied by decreasing low PAN concentrations appeared when the RH increased and vice versa . Laboratory research has demonstrated enhancement of heterogeneous PAN degradation in the presence of water vapor . Although its potential impact has been suggested, the role of RH in the heterogeneous loss of PAN relevant to ambient aerosols remains unclear, hindering analysis of atmospheric oxidation capacity under specific environmental conditions.…”

“…28 Laboratory research has demonstrated enhancement of heterogeneous PAN degradation in the presence of water vapor. 29 Although its potential impact has been suggested, the role of RH in the heterogeneous loss of PAN relevant to ambient aerosols remains unclear, hindering analysis of atmospheric oxidation capacity under specific environmental conditions. Overall, whether heterogeneous loss of PAN will occur on real atmospheric particles, and the corresponding kinetics and mechanisms remain important targets for investigation.…”