Equilibrium solubilities of ammonium benzoate, benzamide and their mixture in supercritical carbon dioxide

The equilibrium solubilities of ammonium benzoate (ABE) and its mixture with benzamide (BZE) in supercritical carbon dioxide were measured at temperatures ranging from 308 to 328 K and pressures from 11.0 to 21.0 MPa using a dynamic flow method. The solubility of ABE in binary (ABE + CO2) system was correlated by 4 semi-empirical models (Chrastil, K–J, M–T and Yu); 2 semi-empirical models (T–G and Sovová) were used to correlate the solubility of ABE in ternary system (ABE + BZE + CO2). In ternary system, both the solubilities decreased as compared to their binary system, the reduction factor (e) and selectivity (α) are defined and calculated respectively. The differences between the solubilities of solid solute in binary and ternary systems were analyzed based on the assumption of molecular competition.

Graphical abstractSchematic diagram of the experimental apparatus.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Solubility of ammonium benzoate and its mixture with benzamide in SCCO2 was measured. ► Experimental data were correlated using 6 semi-empirical models. ► Reduction factor and selectivity in ternary system were defined and calculated.