Experimental determination and correlation of meloxicam sodium salt solubility in supercritical carbon dioxide

A static analytical method was employed for the experimental measurement of the equilibrium solubility of meloxicam sodium salt (MLX) in supercritical carbon dioxide (scCO2), at 303 K, 313 K and 323 K, and in a pressure range from 14.9 up to 25.5 MPa. Experimental equilibrium solubility (in terms of MLX mole fraction) was found to be between 4.41 × 10−6 (at 323 K and 15.2 MPa) and 12.76 × 10−6 (at 323 K and 15.2 MPa). To the best of our knowledge, these are the first MLX equilibrium solubility in scCO2 data to be reported in literature. The obtained experimental data were successfully correlated with three semi-empirical density-based models (Chrastil, Bartle and Méndez-Santiago–Teja models) and with an equation-of-state (EOS) model: the Peng–Robinson cubic equation of state (PR-EOS) together with the conventional van der Waals mixing and combining rules. The best obtained average absolute-relative deviations (AARDs) were 2.7% and 5.3%, for the PR-EOS and for the semi-empirical models, respectively.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Experimental equilibrium solubility measurements of meloxicam sodium salt (MLX) in supercritical carbon dioxide (scCO2). ► Measurements were performed using a static analytical method at 303 K, 313 K and 323 K, and in a pressure range from 14.9 up to 25.5 MPa. ► Equilibrium solubility was found to be between 4.41 × 10−6 (at 323 K and 15.2 MPa) and 12.76 × 10−6 (at 323 K and 15.2 MPa). ► Density-based and Peng–Robinson cubic equation-of-state correlated meloxicam sodium salt–scCO2 equilibria data with AARD lower than 6%.