Adsorption of Atmospheric Gases at the Air−Water Interface. 2. C₁−C₄ Alcohols, Acids, and Acetone

Abstract

Measurements of the temperature- and concentration-dependent surface tensions of aqueous solutions of methanol, 1- and 2-propanol, 1- and 2-butanol, acetic, propionic, and butanoic acids, and acetone were used to determine the standard free energies, enthalpies, and entropies of adsorption from the vapor phase onto a water surface. The saturated surface coverage of all these species is approximately 1014 molecules cm-2. The standard enthalpies of adsorption are correlated to the enthalpies of solution, suggesting that these molecules are partially solvated in the adsorbed state. These results further suggest that atmospheric water droplets could be coated with an organic layer.

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI – heterogeneous reactions with liquid substrates

“…Here, adsorption equilibrium is of wider importance as it may be used to estimate gas surface partitioning which defines the concentration of surface species available for surface reaction or for transfer to the bulk underneath (e.g., in liquid water clouds or aerosols). Thus adsorption of surface-active gases on aqueous solutions (Donaldson and Anderson, 1999) or of gases that form a relatively stable surface complex as intermediate to solvation or to a surface reaction (Donaldson and Valsaraj, 2010) has been described using this concept. Adsorption equilibrium is established when J ads = J des and can be described by:…”

Organics in environmental ices: sources, chemistry, and impacts

“…The latter standard state has been suggested originally by Kemball and Rideal (1946), later used by Donaldson and Anderson (1999), and now also adopted by the IUPAC Subcommittee on Gas Kinetic Data Evaluation . This group has evaluated K LinC values from laboratory data for a range of organic compounds.…”

Organic Aerosols and the Origin of Life: An Hypothesis

“…Laboratory work has shown recently that even small organic molecules tend to concentrate at the water-air interface (Donaldson and Anderson, 1999), and that the presence of salts in the water can lead to large increases in the surface concentration of even the shorter amphiphiles; Demou and Donaldson (2002) observed a ∼50% increase in the surface concentration of hexanoic acid in high ionic strength solutions compared to pure water. This basic molecular mechanism, the 'salting out' effect, should make itself felt on scales as large as the entire ocean surface and as small as the daughter particles produced by asymmetric aerosol fission, see Section 4.…”