Solubility of 1-aminoanthraquinone and 1-nitroanthraquinone in supercritical carbon dioxide

The solubility of 1-aminoanthraquinone (Smoke Orange G) and 1-nitroanthraquinone in supercritical carbon dioxide (scCO(2)) was measured at the temperatures (323.15, 353.15 and 383.15) K and over the pressure range of (12.5-25.0) MPa by a flow type apparatus. Mole fraction solubility of 1-aminoanthraquinone, 3.51 x 10(-5), was significantly higher than that of 1-nitroanthraquinone, 2.52 x 10(-5), as compared at 383.15 K and 25 MPa. It was found that amino group in 1-aminoanthraquinone effects to enhance the solubility of anthraquinone derivatives in supercritical carbon dioxide in comparison with nitro group in 1-nitroanthraquinone. Seven different kinds of semi-empirical models, expressed in terms of CO2 density, were used to correlate the experimental results. Moreover, the solubilities of anthraquinone derivatives were analysed 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). Good agreement with slightly less than 15 per cent of relative deviation between the experimental and calculated solubilities of the anthraquinone derivatives was obtained. (C) 2016 Elsevier Ltd.