Solubility of anthraquinone derivatives in supercritical carbon dioxide

Abstract

Abstract Solubility data of 1-amino-4-hydroxyanthraquinone and 1-hydroxy-4-nitroanthraquinone in supercritical carbon dioxide have been measured at the temperature of 323.15, 353.15 and 383.15 K and over pressure ranges 12.5–25.0 MPa by a flow – type apparatus. The solubility of 1-amino-4-hydroxyanthraquinone was significantly higher than that of 1-hydroxy-4-nitroanthraquinone. It was found that amino group in 1-amino-4-hydroxyanthraquinone can enhance the solubility of anthraquinone derivatives in supercritical carbon dioxide compared with nitro group in 1-hydroxy-4-nitroanthraquinone. The experimental results were correlated satisfactorily by four types of the density-based models, namely, Mendez-Santiago–Teja, Kumar–Johnston, Chrastil, and Sung–Shim. Moreover accurate representation of the solubility of anthraquinone dyestuffs was obtained by the regular solution model with the Flory–Huggins theory as well as the Peng–Robinson equation of state modified by Stryjek and Vera with the van der Waals one-fluid mixing rule.