Atmospheric Chemistry of Sulfur-Containing Compounds: The Effect on the Formation of HONO

The source of atmospheric nitrous acid (HONO) has not yet been fully identified, as observed concentrations remain significantly higher than predicted levels. The hydrolysis reaction of t-ONONO₂, as a feasible source of HONO, has attracted much attention in the field of atmospheric chemistry. In this study, the roles of sulfuric acid (SA), methanesulfonic acid (MSA), and methyl hydrogen sulfate (MHS) in the hydrolysis reaction of t-ONONO₂ to produce HONO and HNO₃ were explored by DFT and statistical dynamics methods. Thermodynamic and kinetic data indicate that SA, MHS, and MSA enhance the hydrolysis reaction of t-ONONO₂ through two mechanisms: single hydrogen atom transfer (S-HAT) and double hydrogen atom transfer (DHAT). Among these, SA exhibits the strongest catalytic effect. This study will contribute to a better understanding of the mechanistic characterization of t-ONONO₂ hydrolysis reactions, which is of great significance for the control of atmospheric particulate matter in polluted areas.