Measurement and correlation of solubility of disperse anthraquinone and azo dyes in supercritical carbon dioxide

The solubility of three disperse anthraquinone dyes and two azo dyes in supercritical CO₂ was measured. The tested dyes are Celliton fast blue B, 1-amino-2-methylanthraquinone, 1-methylaminoanthraquinone, disperse Red 1 and 4-[4-(phynylazo)phenylazo]-o-cresol. Solubility measurements were made at 313.15-393.15 K and 10-25 MPa in a high-temperature autoclave phase equilibrium apparatus. Pure physical properties of the dyes such as critical constants, molar volumes and vapor pressures were estimated based on semi-empirical methods. Also, the data were quantitatively modeled by both an empirical density correlation and a quantitative equation of state recently proposed by the present authors based on nonrandom lattice theory. We found that anthraquinone disperse dyes in general show higher solubility than azo disperse dyes in supercritical CO₂ within the experimental ranges.