Solid/Liquid Phase Diagram of the Ammonium Sulfate/Glutaric Acid/Water System

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2013-05, Vol.117 (17), p.3630-3641
• Main Authors: Beyer, Keith D, Pearson, Christian S, Henningfield, Drew S
• Format: Article
• Language: English
• Subjects: Ammonium Sulfate - chemistry; Ammonium sulfates; Calorimetry; Chemical thermodynamics; Chemistry; Exact sciences and technology; Freezing point; General and physical chemistry; General. Theory; Glutarates - chemistry; Kinetics; Phase boundaries; Phase diagrams; Ternary systems; Thermodynamic models; Thermodynamics; Water - chemistry; Water activity
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp401648y

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.