AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Importance of Water to Heterogeneous Reaction of Peroxides on Authentic Particles
Qinqin Wu, Liubin Huang, Hao Liang, Yue Zhao, Dao Huang, ZHONGMING CHEN, Peking University
Abstract Number: 586 Working Group: Haze in China: Sources, Formation Mechanisms, and Current Challenges
Abstract Peroxides, including hydrogen peroxide (H2O2) and organic peroxide, play important roles in the oxidative capacity of atmosphere and the formation of secondary aerosols formation. Here we present the laboratory study of the heterogeneous reaction of H2O2 and peroxyacetic acid (PAA, an important organic peroxide) on authentic PM2.5 particles, and we compare their heterogeneous behaviors on PM2.5 particles with those on authentic Asian Mineral Dust (AMD) particles and Arizona Test Dust (ATD) particles. It is found that the uptake coefficient (γ) of H2O2 and PAA on authentic particles (PM2.5 and AMD) has a positive correlation with relative humidity (RH), while γH2O2 and γPAA on ATD show a negative correlation with RH. Moreover, on PM2.5 particles, γPAA is more sensitive to RH variation than H2O2 does. Considering the larger Henry’s law constant of H2O2 than that of PAA, we suggest that the chemical process dominate the uptake of peroxides on PM2.5, rather than the physical process. The composition analysis result shows that the concentrations of NO3- and SO42- in PM2.5 and AMD particles are 1-3 order of magnitudes larger than those in ATD particles. We suggest that in addition to the traditionally recognized the surface active sites (e.g., OH groups, lattice oxygen), the soluble ions have potential effects on the heterogeneous reaction of peroxides on authentic particles. The existence of soluble ions might promote the formation of aqueous film with RH increasing and enhance the aqueous reaction of peroxides. The reaction on the standard test dust particles could not well represent the real atmospheric heterogeneous reaction, especially under humid conditions.