Surface/bulk partitioning and acid/base speciation of aqueous decanoate: direct observations and atmospheric implications

Summary, in English

Dilute aqueous solutions of the atmospheric organic surfactant sodium decanoate have been studied using surface sensitive X-ray photoelectron spectroscopy combined with synchrotron radiation. We studied the decanoate/decanoic acid speciation and preferential adsorption at the vapor-liquid interface, and the responses to mixing in solution with some of the most common atmospheric inorganic ions, Na+, NH4+, Cl-, and SO42-. We observe little or no influence of Na+, Cl-, or SO42- ions, on neither the relative speciation nor the individual adsorption properties of decanoate and decanoic acid. In particular, no significant salting-out effect due to common Na+ cations of the organic and inorganic salts was observed for these solutions. On the other hand, mixing with NH4+ cations resulted in a pronounced surface enhancement of decanoic acid, which is attributed to surface specific acid-base chemistry. These changes in surface/bulk partitioning and surface speciation may significantly affect properties of aqueous droplets containing decanoate/decanoic acid, and potential implications for several processes critical to the climate effects of atmospheric aerosols are discussed.

• Författare: N. L. Prisle; N. Ottosson; Gunnar Öhrwall; J. Soderstrom; M. Dal Maso; O. Bjorneholm
• Avdelning/ar: MAX IV-laboratoriet
• Publiceringsår: 2012
• Språk: Engelska
• Sidor: 12227-12242
• Publikation/Tidskrift/Serie: Atmospheric Chemistry and Physics
• Volym: 12
• Issue: 24
• Länkar: http://dx.doi.org/10.5194/acp-12-12227-2012
• Dokumenttyp: Artikel i tidskrift
• Förlag: Copernicus GmbH
• Ämne: Physical Sciences; Natural Sciences
• Status: Published
• ISBN/ISSN/Övrigt: ISSN: 1680-7324