Journal Articles ACS Earth and Space Chemistry Year : 2022

NaCl salts in finite aqueous environments at the fine particle marine aerosol scale

Abstract

We investigated isolated sodium/chloride aqueous droplets at the microscopic level, which comprise from about 5k to 1M water molecules and whose salt concentrations are 0.2m (brackish water) and 0.6m (sea water), by means of molecular dynamics simulations based on an ab initio-based polarizable force field. The size of our largest droplets is at the submicron particle marine aerosol scale. From our simulations, we investigated ion spatial distributions, ion aggregates (size, composition, lifetime and distribution), droplet surface potentials and the densities of the water vapor surrounding the droplets. Regarding ions, they form a weak electrostatic double layer extending from the droplet boundary to 2~nm within the droplet interior. Free Na+ and ion aggregates are more repelled from the boundary than free Cl-. Most of the droplet properties depend on the droplet radius R according to the standard formula A=A(1 - 2 δ/R), where A is the bulk magnitude of the quantity A and δ is a length at most at the~nm scale. Regarding the water vapor densities they obey a Kelvin relation corresponding to a surface tension whose Tolman length is negative and at the 1~nm scale. That length is about one order of magnitude larger than for pure water droplets, however it is weak enough to support the reliability of a standard Kelvin term (based on planar interface surface tensions and water densities) and of the related Kölher equation to model sub-micron salty aerosols.
Fichier principal
Vignette du fichier
2109.15265 (12.72 Mo) Télécharger le fichier
Origin Publisher files allowed on an open archive

Dates and versions

hal-03360947 , version 1 (26-11-2023)

Identifiers

Cite

Valérie Vallet, Jonathan Coles, Florent Réal, Houriez Céline, Michel Masella. NaCl salts in finite aqueous environments at the fine particle marine aerosol scale. ACS Earth and Space Chemistry, 2022, 6 (6), pp.1612-1626. ⟨10.1021/acsearthspacechem.2c00082⟩. ⟨hal-03360947⟩
283 View
16 Download

Altmetric

Share

More