title: Effect of inorganic salts on the volatility of organic acids.
abstract: Particulate phase reactions between organic and inorganic compounds may significantly alter aerosol chemical properties, for example, by suppressing particle volatility. Here, chemical processing upon drying of aerosols comprised of organic (acetic, oxalic, succinic, or citric) acid/monovalent inorganic salt mixtures was assessed by measuring the evaporation of the organic acid molecules from the mixture using a novel approach combining a chemical ionization mass spectrometer coupled with a heated flow tube inlet (TPD-CIMS) with kinetic model calculations. For reference, the volatility, i.e. saturation vapor pressure and vaporization enthalpy, of the pure succinic and oxalic acids was also determined and found to be in agreement with previous literature. Comparison between the kinetic model and experimental data suggests significant particle phase processing forming low-volatility material such as organic salts. The results were similar for both ammonium sulfate and sodium chloride mixtures, and relatively more processing was observed with low initial aerosol organic molar fractions. The magnitude of low-volatility organic material formation at an atmospherically relevant pH range indicates that the observed phenomenon is not only significant in laboratory conditions but is also of direct atmospheric relevance.
authors.affiliation: Department of Chemical Engineering, Columbia University , 500 West 120th Street, New York, New York 10027, United States.
authors.forename: Silja A K
authors.initials: SA
authors.lastname: Häkkinen
authors.forename: V Faye
authors.initials: VF
authors.lastname: McNeill
authors.forename: Ilona
authors.initials: I
authors.lastname: Riipinen
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D000336:Aerosols / Q000737:chemistry*; D000390:Air Ionization; D002264:Carboxylic Acids / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry; D007700:Kinetics; D013058:Mass Spectrometry / Q000379:methods*; D008962:Models, Theoretical; D019815:Oxalic Acid / Q000737:chemistry; D012492:Salts; D019802:Succinic Acid / Q000737:chemistry; D055548:Vapor Pressure; D014835:Volatilization
chemical_list: D000336:Aerosols; D002264:Carboxylic Acids; D012492:Salts; D019343:Citric Acid; D019815:Oxalic Acid; D019802:Succinic Acid; D019342:Acetic Acid