Thermodynamic evaluation and optimization of LiNO3–KNO3–NaNO3 ternary system

Abstract

The phase diagram of LiNO3–KNO3 system was investigated with differential scanning calorimetry. Phase transitions data of LiNO3–KNO3 system were obtained. Using the measured phase equilibrium data as well as other available phase equilibrium and thermodynamic data in literature, the thermodynamic optimization of parameters for all phases and compounds in the LiNO3–NaNO3–KNO3 system was performed. The Modified Quasichemical Model was applied for the liquid phase, and Compound Energy Formalism was used for the NaNO3–KNO3 solid solutions. The compound KNO3·LiNO3 was treated with Neumann-Kopp rule. The optimized parameters were used to predict the phase diagram of LiNO3–NaNO3–KNO3 ternary system and the predicted ternary invariant points were experimentally verified.