Abstract

LOVERA, Jorge A.; USHAK, Svetlana  and  GRAGEDA, Mario. Theoretical and experimental determination of solubility of the NaNO₃-Mn(NO₃)₂-H₂O system at 25 °C and its application to phase change materials. RevActaNova. [online]. 2024, vol.11, n.4, pp.335-343.  Epub Nov 30, 2024. ISSN 1683-0789.  https://doi.org/10.35319/acta-nova.202423.

In this work, the solubility of the ternary system NaNO3-Mn(NO3)2-H2O at 25 °C was determined experimentally by the traditional wet waste method and theoretically by the BET model, both results were consistent. The system formed an invariant point and the solid phases anhydrous NaNO3 and Mn(NO3)2-4H2O. A readjustment of the correlation coefficients of the equilibrium constant with temperature for NaNO3 was necessary. From the prediction of the polythermal curve with the model, a eutectic mixture was found with a mass composition of 3.82 % NaNO3, 96.18 % Mn(NO3)2-6H2O, and a temperature of 22.6°C. The latter was verified experimentally with measurements of crystallization and melting behavior, giving a small difference of 0.6 °C. The results found in this study can be applied to the simulation of nitrate salt separation processes and/or to the deeper design of phase change materials with operating temperature close to the melting point.

Keywords : Nitrate solubility; BET model; eutectic mixture; phase change material.

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