Dark air\u2013liquid interfacial chemistry of glyoxal and hydrogen peroxide

Fei Zhang,Zihua Zhu,Xiaofei Yu,Xiao-Ying Yu,Jianmin Chen

doi:10.1038/s41612-019-0085-5

Abstract

The air–liquid (a–l) interfacial chemistry of glyoxal is of great interest in atmospheric chemistry. We present molecular imaging of glyoxal and hydrogen peroxide (H2O2) dark aging using in situ time-of-flight secondary ion mass spectrometry (ToF-SIMS). More organic peroxides and cluster ions are observed at the a–l interface in dark aging compared to UV aging. Cluster ions formed with more water molecules in dark aging indicate that the aqueous secondary organic aerosol (aqSOA) could form hydrogen bond with water molecules, suggesting that aqSOAs at the aqueous phase are more hydrophilic. Thus the interfacial aqSOA in dark aging could increase hygroscopic growth. Strong contribution of cluster ions and large water clusters in dark aging indicates change of solvation shells at the a–l interface. The observation of organic peroxides and cluster ions indicates that the aqueous surface could be a reservoir of organic peroxides and odd hydrogen radicals at night. Our findings provide new understandings of glyoxal a–l interfacial chemistry and fill in the gap between field measurements and the climate model simulation of aqSOAs.

Highlights

Secondary organic aerosol (SOA) formation occurring at the air–liquid (a–l) interface is important in atmospheric chemistry and its impact on global climate modeling.[1,2,3] SOA is defined as the organic mass produced by gas-to-particle partition and oxidation of vapors of semivolatile compounds or volatile organic compounds (VOCs) in the atmosphere.[4]
We find the following during dark aging: (1) the a–l surface will be more hydrophilic with increased dark-aging time, (2) more cluster ions form at the aqueous surface in dark aging compared with UV
Without UV irradiation, glyoxal undergoes oxidation by H2O2 with a rate constant of (1.67 ± 0.80) × 10−4 M−1 s−1.33 reactions are slower in dark aging than photochemical aging, carboxylic acids, organic peroxides, and other products are detected (Table 1).[34]

Summary

Introduction

Secondary organic aerosol (SOA) formation occurring at the air–liquid (a–l) interface is important in atmospheric chemistry and its impact on global climate modeling.[1,2,3] SOA is defined as the organic mass produced by gas-to-particle partition and oxidation of vapors of semivolatile compounds or volatile organic compounds (VOCs) in the atmosphere.[4]. Glyoxal contributed up to 15% of SOA mass in Mexico city.[10] Hydrogen peroxide (H2O2) plays a vital role in the nonradical oxidation of aldehydes and dialdehydes, contributing to the SOA burden in addition to radical oxidation pathway.[6] Recent observation of hydroxyhydroperoxides (α-HHPs) from glyoxal and H2O2 oxidation improved the SOA simulation.[11,12]

Methods

Results

Conclusion