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Updated: May 26, 2026

Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers
Published on: September 4, 2015
Solid/liquid phase diagram of the ammonium sulfate/malic acid/water system
Jason R Schroeder1, Christian S Pearson, Keith D Beyer
1Department of Chemistry, University of Wisconsin-La Crosse, La Crosse, Wisconsin 54601, USA.
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.
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