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

Abstract

We have studied the low temperature phase diagram and water activities of the ammonium sulfate/malic acid/water system using differential scanning calorimetry (DSC) and infrared spectroscopy (IR) of thin films. Using the results from our experiments we have mapped the ice primary phase region of the solid/liquid ternary phase diagram. In our DSC and IR experiments we observe ice nucleation in all samples and ammonium sulfate in some samples, which were cooled to 183 K. However, we only observed malic acid nucleation in IR experiments, where the sample was in contact with ZnSe windows. We also compare our results 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, the E-AIM has difficulty predicting malic acid crystallization.

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

“…In the case of C 4 H 6 O 5 /(NH 4 ) 2 SO 4 /H 2 O, we never observed a ternary concentration at which all three solids formed. At most, two solids formed (either ice/solid C 4 H 6 O 5 or ice/solid (NH 4 ) 2 SO 4 ), and for most concentrations, only one solid formed (ice) . This leads to the conclusion that the C 4 H 6 O 5 /NH 4 + /SO 4 2– interactions are favorable in solution, leading to a very low ternary eutectic temperature.…”

“…We have studied five dicarboxylic acid/(NH 4 ) 2 SO 4 /H 2 O ternary systems in our lab: C 3 H 4 O 4 /(NH 4 ) 2 SO 4 /H 2 O, C 4 H 4 O 4 /(NH 4 ) 2 SO 4 /H 2 O, C 4 H 6 O 5 /(NH 4 ) 2 SO 4 /H 2 O, C 5 H 8 O 4 /(NH 4 ) 2 SO 4 /H 2 O, and C 4 H 6 O 4 /(NH 4 ) 2 SO 4 /H 2 O studied in this paper. Table summarizes some of the key physical properties that we measured in these systems.…”

“…At most, two solids formed (either ice/solid C 4 H 6 O 5 or ice/solid (NH 4 ) 2 SO 4 ), and for most concentrations, only one solid formed (ice). 45 This leads to the conclusion that the C 4 H 6 O 5 /NH 4 + /SO 4 2− interactions are favorable in solution, leading to a very low ternary eutectic temperature. This may not be surprising for C 4 H 6 O 5 given that it has three OH bonds and two CO bonds (more than the other dicarboxylic acids that we studied), which would lead to strong interactions with water and NH 4 + /SO 4 2− ions.…”

Explanation and Exploration of the Isothermal Titration Curve for the NaCl + Na2SO4+ H2O System at 298.15 K and 102.2 kPa

“…Additionally, phase equilibrium has a considerable basic groundwork in the metal smelting process, fractional crystallization, semiconductors, ceramics, salt separation, and purification in natural ores. , The construction of ternary equilibrium phase diagrams is at the basis of these applications. Thermal analysis is a very useful practical method for studying phase diagrams, − and calorimetric methods have been an invaluable tool for understanding the rich phase behaviors either in the early stages of process development or in phase equilibrium applications. Isothermal titration microcalorimetry (ITC) and reaction calorimetry are widely used calorimetric techniques alongside differential scanning calorimetry.…”

Solid–Liquid Phase Equilibrium in the Na₂CO₃+Na₂SO₄+H₂O System at 298.15 K and 101 kPa by Isothermal Titration Microcalorimetry

“…ermal analysis includes gravimetric analysis (TG; Li and Guo, 2020), differential thermal analysis (Sergeev et al, 2015), di erential scanning calorimetry (DSC; Schroeder et al, 2012;Beyer et al, 2013;Noshadi and Sadeghi, 2018), titration calorimetry (Dhenain et al, 2013;Frangieh et al;2014), etc. An appropriate analysis method must be selected for each speci c system.…”