Solid–liquid equilibrium and thermodynamic analysis of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in nitric acid + chloroform binary solvent mixtures

The solubility of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in nitric acid + chloroform Binary mixed solvents was systematically investigated over the temperature range of 283.15 K to 323.15 K using the laser dynamic method. To broaden the applicability of the experimental data, the experimental solubility data were correlated using the modified Apelblat, van’t Hoff, CNIBS/R–K, and modified Jouyban–Acree models, with the modified Apelblat model providing the best overall correlation performance. In addition, the apparent thermodynamic parameters of dissolution, including the standard dissolution enthalpy (ΔHdis∘), standard dissolution entropy (ΔSdis∘), and standard Gibbs free energy (ΔGdis∘), were determined to provide further insight into the dissolution behavior of RDX in the mixed solvent system. The obtained data provide fundamental thermodynamic information for solvent-system evaluation, solution-phase process design, and crystallisation studies involving RDX. Furthermore, these findings offer a sound basis for future investigations into the crystallisation behaviour and separation processes of RDX.