Measurement and correlation of solubility of HNIW·TNT co-crystal in (methanol/1,2-dichloroethane + ethyl acetate) solvent mixtures from 283.15 to 318.15 K

Abstract The solubility of HNIW·TNT co-crystal was experimentally measured by a gravimetric method in (methanol + ethyl acetate) and (1,2-dichloroethane + ethyl acetate) solvent mixtures at the temperature range from 283.15 to 318.15 K under atmospheric pressure (p = 0.1 MPa). The measured results indicate that the solubilities of HNIW·TNT co-crystal were significantly affected by the temperature and the mole fraction of methanol or 1,2-dichloroethane. Within the range of the molar fraction of methanol and 1,2-dichloroethane, the average solubilities of HNIW·TNT co-crystal in the corresponding binary solvent mixtures decreased from (7.63 × 10−2) to (0.82 × 10−2, 7.66 × 10−2) to (1.75 × 10−2), respectively. The modified Apelblat equation, the CNIBS/R-K model, the Van't Hoff-Jouyban-Acree model, and the Apelblat-Jouyban-Acree model were successfully used to correlate the experimental solubility of HNIW·TNT co-crystal, and the calculated solubility data are good agreement with the experimental data. In addition, the calculated values of the molar enthalpy change (∆solH°) and the Gibbs free energy change (∆solG°) indicated that the dissolution behavior of HNIW·TNT co-crystal in the solvent mixtures is endothermic and not spontaneous. In this work, the experimental solubility and correlation equations, as well as the thermodynamic parameters of HNIW·TNT co-crystal during the dissolution process were obtained, which would be useful for facilitating the industrial crystallization process of HNIW·TNT co-crystal and further theoretical studies.