This study systematically investigated the phase equilibrium behavior of 3-nitro-1,2,4-triazol-5-one (NTO) dissolution in acetic acid + water binary solvent systems. Using laser dynamic monitoring under atmospheric pressure (0.1 MPa), dissolution equilibrium data were experimentally determined across a temperature range of 293.15–333.15 K. Maximum dissolution capacity was observed at an acetic acid molar fraction of \(x_{\mathrm{CH_{3} COOH}} = 0.73\) attributed to multilevel hydrogen-bonding synergism between solvent components and solute molecules. To establish generalized predictive models, four thermodynamic frameworks—the Apelblat equation, van’t Hoff temperature correlation, Yaws empirical model, and Jouyban-Acree multivariate regression—were applied, all demonstrating excellent correlation with experimental data (average R2 > 0.99). Thermodynamic analysis yielded critical dissolution parameters: standard dissolution enthalpy, entropy, and Gibbs free energy, confirming an entropy-driven dissolution mechanism. The compiled phase equilibrium database and validated models provide theoretical guidance for optimizing NTO crystallization processes in industrial applications, while establishing foundational data for molecular design in multicomponent solvent systems for energetic materials.
