Direct observation of the complex S(IV) equilibria at the liquid-vapor interface

Autor: Tillmann Buttersack, Ivan Gladich, Shirin Gholami, Clemens Richter, Rémi Dupuy, Christophe Nicolas, Florian Trinter, Annette Trunschke, Daniel Delgado, Pablo Corral Arroyo, Evelyne A. Parmentier, Bernd Winter, Lucia Iezzi, Antoine Roose, Anthony Boucly, Luca Artiglia, Markus Ammann, Ruth Signorell, Hendrik Bluhm
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Nature Communications, Vol 15, Iss 1, Pp 1-8 (2024)
Druh dokumentu: article
ISSN: 2041-1723
DOI: 10.1038/s41467-024-53186-5
Popis: Abstract The multi-phase oxidation of S(IV) plays a crucial role in the atmosphere, leading to the formation of haze and severe pollution episodes. We here contribute to its understanding on a molecular level by reporting experimentally determined pK a values of the various S(IV) tautomers and reaction barriers for SO2 formation pathways. Complementary state-of-the-art molecular-dynamics simulations reveal a depletion of bisulfite at low pH at the liquid-vapor interface, resulting in a different tautomer ratio at the interface compared to the bulk. On a molecular-scale level, we explain this with the formation of a stable contact ion pair between sulfonate and hydronium ions, and with the higher energetic barrier for the dehydration of sulfonic acid at the liquid-vapor interface. Our findings highlight the contrasting physicochemical behavior of interfacial versus bulk environments, where the pH dependence of the tautomer ratio reported here has a significant impact on both SO2 uptake kinetics and reactions involving NO x and H2O2 at aqueous aerosol interfaces.
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