title: Effect of ammonia on the volatility of organic diacids.
abstract: The effect of ammonia on the partitioning of two dicarboxylic acids, oxalic (C2) and adipic (C6) is determined. Measurements by a tandem differential mobility analysis system and a thermodenuder (TD-TDMA) system are used to estimate the saturation vapor pressure and enthalpy of vaporization of ammonium oxalate and adipate. Ammonia dramatically lowered the vapor pressure of oxalic acid, by several orders of magnitude, with an estimated vapor pressure of 1.7 ± 0.8 × 10(–6) Pa at 298 K. The vapor pressure of ammonium adipate was 2.5 ± 0.8 × 10(–5) Pa at 298 K, similar to that of adipic acid. These results suggest that the dominance of oxalate in diacid concentrations measured in ambient aerosol could be attributed to the salt formation with ammonia.
authors.affiliation: Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Paciga
authors.forename: Ilona
authors.initials: I
authors.lastname: Riipinen
authors.forename: Spyros N
authors.initials: SN
authors.lastname: Pandis
mesh_terms: D000272:Adipates / Q000737:chemistry*; D000336:Aerosols / Q000737:chemistry*; D000393:Air Pollutants / Q000737:chemistry*; D019815:Oxalic Acid / Q000737:chemistry*; D013816:Thermodynamics; D055548:Vapor Pressure; D014835:Volatilization
chemical_list: D000272:Adipates; D000336:Aerosols; D000393:Air Pollutants; C029900:adipic acid; D019815:Oxalic Acid