Liquid-phase reactions of aromatic organosulfates with OH radicals: kinetics, mechanisms, and environmental effects

Abstract

Aromatic organosulfates (aromatic OSs) are widely detected in the atmosphere and exhibit high abundance in urban areas. However, the atmospheric fate and environmental impacts of aromatic OSs remain poorly understood. In this study, we investigated the liquid-phase reactions of three aromatic OSs (i.e., phenyl sulfate, p-tolyl sulfate, and 4-ethylphenyl sulfate) with OH radicals (⚫OH). The second-order reaction rate constants (k) of aromatic OSs with ⚫OH were measured in the range of 4.3–6.4×109M-1s-1 at different pHs. It is found that k values are similar for the homologues of aromatic OSs, whereas they are slightly affected by the solution pHs. These three aromatic OSs oxidized by ⚫OH mainly yielded functionalized OSs, along with fragmented OSs and inorganic sulfate. The observation of inorganic sulfate formation, for the first time, indicates that aromatic OSs can also be converted into inorganic sulfate in analogous to aliphatic OSs. Furthermore, generated functionalized OSs can significantly enhance the light absorption capacity, particularly under acidic conditions. These findings provide new insights into the understanding of the fate of aromatic OSs in the atmosphere that they can rapidly undergo atmospheric transformation, affecting the atmospheric sulfur cycle and altering aerosol optical properties.