From O2--Initiated SO2 Oxidation to Sulfate Formation in the Gas Phase

Narcisse T Tsona; Junyao Li; Lin Du

doi:10.1021/acs.jpca.8b03381

From O₂^--Initiated SO₂ Oxidation to Sulfate Formation in the Gas Phase

J Phys Chem A. 2018 Jul 12;122(27):5781-5788. doi: 10.1021/acs.jpca.8b03381. Epub 2018 Jul 2.

Authors

Narcisse T Tsona¹, Junyao Li¹, Lin Du¹

Affiliation

¹ Environment Research Institute , Shandong University , Shanda South Road 27 , 250100 Shandong , China.

PMID: 29923718
DOI: 10.1021/acs.jpca.8b03381

Abstract

We have investigated the chemical fate of O₂SOO^-, the immediate product of the reaction between sulfur dioxide (SO₂) and the superoxide ion (O₂^-), by reactions with nitrogen oxides (NO and NO₂) using high-level theoretical calculations. Both reactions with NO and NO₂ lead to exergonic formation of adducts, which subsequently overcome low energy barriers to form SO₃ + NO₃^- and SO₄^- + NO, with rate constants of 6.9 × 10^-10 and 6.3 × 10^-10 cm³ molecule^-1 s^-1, respectively. Reactions with water are ∼15-23 times slower than corresponding naked reactions at ambient conditions, hence not slow enough to be prevented at these conditions. The studied reactions not only are useful for understanding ionic SO₂ oxidation in the atmosphere and in chamber experiments but also provide a new mechanism for the gas-phase formation of sulfate from an ion-induced mechanism. These reactions may enhance our understanding of the early stages of secondary aerosol formation.