Measurement and Correlation of Derivatized Anthraquinone Solubility in Supercritical Carbon Dioxide

Solubilites of 1,4-diamino-2,3-dichloroanthraquinone (C.I. Disperse Violet 28) and 1,8-dihydroxy-4,5-dinitroanthraquinone in supercritical carbon dioxide (sc-CO2) were measured at the temperature of (323.15, 353.15 and 383.15) K and over pressure ranges (12.5 to 25.0) MPa by a flow-type apparatus. Mole fraction solubility of 1,4-diamino-2,3-dichloroanthraquinone (C.I. Disperse Violet 28) is found significantly higher than that of 1,8-dihydroxy-4,5-dinitroanthraquinone. It was found that 2,3-dichloro group addition onto 1,4-diaminoanthraquione leads to higher solubility of 1,4-diaminoanthraquinone and the addition of 8-hydroxy-5-nitro group on 1-hydroxy-4-nitroanthraquione causes lower solubility than that of 1-hydroxy-4-nitroanthraquinone. Three semiempirical density-based models, Mendez-Santiago-Teja, Sung-Shim, and Bartle et al., were used to correlate the experimental results. Moreover, the solubilities of anthraquinone derivatives were analyzed thermodynamically by the regular solution model with the Flory-Huggins theory and by the Peng-Robinson equation of state with a modification of Stryjek and Vera (PRSV-EOS). The calculated solubilities of anthraquinone derivatives were in good agreement with the experimental results.