Crystallization thermodynamics of FOX-7 in three binary mixed solvents

Abstract

The solubility of 1,1-diamino-2,2-dinitroethylene (FOX-7) in three binary mixed solvents (DMSO+H2O, EtOH, ACE) at different temperatures from (293.15 to 333.15) K were determined by using a laser dynamic monitoring technique. The results showed that the solubility of FOX-7 in mixed solvent increases with increasing the temperature and DMSO content. The modified Apelblat equation, van't Hoff equation, CNIBS/R-K model and Jouyban-Acree model was adopted to correlate the experimental solubility data, and all of these models provided a satisfactory result in binary solvents. In addition, the thermodynamic properties of the solution of different binary mixed solvents, such as enthalpy, Gibbs energy and entropy can be calculated by the van't Hoff equation and the Gibbs equation. Solid-liquid surface tension and surface entropy factor of FOX-7 were estimated by using the experimental solubility data. The solubility of FOX-7 will provide essential support for the further research of crystallization and spheroidization of FOX-7. The morphology of products crystallized in the DMSO+EtOH mixed solvent (xDMSO = 0.7668) were uniform and regular, which were observed by electron microscopy. The particle size distribution of the products was characterized by the BT-2002 laser particle size analyzer. The results showed that the products particle size distribution was narrow and uniform.