Heterogeneous reactions of glyoxal on mineral particles: A new avenue for oligomers and organosulfate formation

Glyoxal (GL) plays a crucial role in the formation of secondary organic aerosols (SOA), because it is highly water soluble and capable of oligomerization. This is the first study to describe irreversible heterogeneous reactions of GL on clean and acidic gas-aged SiO2, alpha-Al2O3, and CaCO3 particles, as models of real mineral particles, at various relative humidity and without irradiation and gas phase oxidants. A series of products, including oligomers, organosulfates, and organic acids, which contribute to SOA formation, were produced. GL uptake on SO2-aged alpha-Al2O3 enabled the oxidation of surface S(IV) to S(VI). The presence of adsorbed water on particles favored GL uptake and the formation of oligomers and organosulfate, but it suppressed organic acid formation. In addition, the aging process enhanced the positive effect of adsorbed water on GL uptake. These findings will further our understanding of the GL sink and SOA sources in the atmosphere. (C) 2016 Elsevier Ltd. All rights reserved.National Natural Science Foundation of China [21077003, 41275125, 21190053, 41121004]; State Key Laboratory of Environment Simulation and Pollution Control (special fund)SCI(E)EIARTICLEzmchen@pku.edu.cn133-14013