title: Solid/liquid phase diagram of the ammonium sulfate/glutaric acid/water system.
abstract: We have studied the low temperature phase diagram and water activities of the ammonium sulfate/glutaric acid/water system using differential scanning calorimetry, infrared spectroscopy of thin films, and a new technique: differential scanning calorimetry-video microscopy. Using these techniques, we have determined that there is a temperature-dependent kinetic effect to the dissolution of glutaric acid in aqueous solution. We have mapped the solid/liquid ternary phase diagram, determined the water activities based on the freezing point depression, and determined the ice/glutaric acid phase boundary as well as the ternary eutectic composition and temperature. We have also modified our glutaric acid/water binary phase diagram previously published based on these new results. We compare our results for the ternary system to the predictions of the Extended AIM Aerosol Thermodynamics Model (E-AIM), and find good agreement for the ice melting points in the ice primary phase field of this system; however, significant differences were found with respect to phase boundaries, concentration and temperature of the ternary eutectic, and glutaric acid dissolution.
authors.affiliation: Department of Chemistry, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA. kbeyer@uwlax.edu
authors.forename: Keith D
authors.initials: KD
authors.lastname: Beyer
authors.forename: Christian S
authors.initials: CS
authors.lastname: Pearson
authors.forename: Drew S
authors.initials: DS
authors.lastname: Henningfield
mesh_terms: D000645:Ammonium Sulfate / Q000737:chemistry*; D005977:Glutarates / Q000737:chemistry*; D007700:Kinetics; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D005977:Glutarates; D014867:Water; C035736:glutaric acid; D000645:Ammonium Sulfate