Cosolvent Effect on the Solubility of Ammonium Benzoate in Supercritical Carbon Dioxide

Using a dynamic method, the experimental solubility of ammonium benzoate (ABE) in supercritical carbon dioxide (SCCO2) with a cosolvent of ethanol, acetone, or ethylene glycol was measured at a temperature of 318 K, a cosolvent mole fraction of 0.02, and a pressure range from 11.0 to 21.0 MPa; under the same pressure conditions, the solubility of ABE in SCCO2 with the ethanol cosolvent was further determined at temperatures of 308, 318, and 328 K and cosolvent molar concentrations of 0.01, 0.02, and 0.04. The experimental data were correlated with four semi-empirical models (Gonzalez, Thakur, Sovova, and Tang) commonly used for supercritical systems with a cosolvent, and satisfactory correlated results were obtained with an average absolute relative deviation value of 6.58% by the Tang model. In addition, to provide a theoretical explanation for the experimental phenomena, a new interpretation from a microcosmic point of view was proposed based on gas-phase density functional theory through the Gaussian 09 approach. The molecular interaction calculation results and experimental observation showed a sustainable agreement.

Automated summary

This study experimentally measured the solubility of ammonium benzoate (ABE) in supercritical carbon dioxide (SCCO2) with different cosolvents and correlated the experimental data with four semi-empirical models. In addition, a new interpretation based on molecular interaction calculations was proposed to explain the experimental phenomena.