title: Hygroscopic Characteristics of Alkylaminium Carboxylate Aerosols.
abstract: The hygroscopic growth factor (HGF) and cloud condensation nuclei (CCN) activity for a series of alkylaminium carboxylate aerosols have been measured using a hygroscopicity tandem differential mobility analyzer coupled to a condensation particle counter and a CCN counter. The particles, consisting of the mixtures of mono- (acetic, propanoic, p-toluic, and cis-pinonic acid) and dicarboxylic (oxalic, succinic, malic, adipic, and azelaic acid) acid with alkylamine (mono-, di-, and trimethylamines), represent those commonly found under diverse environmental conditions. The hygroscopicity parameter (κ) of the alkylaminium carboxylate aerosols was derived from the HGF and CCN results and theoretically calculated. The HGF at 90% RH is in the range of 1.3 to 1.8 for alkylaminium monocarboxylates and 1.1 to 2.2 for alkylaminium dicarboxylates, dependent on the molecular functionality (i.e., the carboxylic or OH functional group in organic acids and methyl substitution in alkylamines). The κ value for all alkylaminium carboxylates is in the range of 0.06-1.37 derived from the HGF measurements at 90% RH, 0.05-0.49 derived from the CCN measurements, and 0.22-0.66 theoretically calculated. The measured hygroscopicity of the alkylaminium carboxylates increases with decreasing acid to base ratio. The deliquescence point is apparent for several of the alkylaminium dicarboxylates but not for the alkylaminium monocarboxylates. Our results reveal that alkylaminium carboxylate aerosols exhibit distinct hygroscopic and deliquescent characteristics that are dependent on their molecular functionality, hence regulating their impacts on human health, air quality, and direct and indirect radiative forcing on climate.
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77840, United States.
authors.forename: Mario
authors.initials: M
authors.lastname: Gomez-Hernandez
authors.affiliation: Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Megan
authors.initials: M
authors.lastname: McKeown
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77840, United States.
authors.forename: Jeremiah
authors.initials: J
authors.lastname: Secrest
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77840, United States.
authors.forename: Wilmarie
authors.initials: W
authors.lastname: Marrero-Ortiz
authors.affiliation: Department of Earth and Planetary Science, Weizmann Institute of Science , Rehovot, 76100 Israel.
authors.forename: Avi
authors.initials: A
authors.lastname: Lavi
authors.affiliation: Department of Earth and Planetary Science, Weizmann Institute of Science , Rehovot, 76100 Israel.
authors.forename: Yinon
authors.initials: Y
authors.lastname: Rudich
authors.affiliation: Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Don R
authors.initials: DR
authors.lastname: Collins
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77840, United States.|Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Renyi
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D000588:Amines / Q000737:chemistry; D001272:Atmosphere; D002980:Climate; D003998:Dicarboxylic Acids / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D017155:Wettability
chemical_list: D000336:Aerosols; D000588:Amines; D003998:Dicarboxylic Acids; D009930:Organic Chemicals