LAUSR

Abstract Using a mixture of dyes to produce a variety of shades is necessary for the industrialization of supercritical fluid dyeing. The solubility of the mixture in supercritical fluid is indispensable for combination dyeing but has been less well-studied. In this study, the solubility of trichromatic disperse dyes (C.I. Disperse Orange 30, C.I. Disperse Red 167 and C.I. Disperse Blue 79) and their blends in supercritical carbon dioxide were measured at temperatures of 333.15, 363.15, and 393.15 K and pressures of 12, 16, 20, and 24 MPa. Considering both the solubility enhancement value and the statistical significance, the solubility of a quaternary system was less than that of a binary system, particularly at higher pressure. To research the relationship between solubility and experimental conditions or properties of the solute, the experimental data were correlated with two semiempirical models (the Kumar–Johnston (K-J) and Sung–Shim (S-S) models) and a phase equilibrium thermodynamic model (a modified Redlich–Kwong equation of state (m-RK-EOS)). The results showed that the calculated solubility by the semiempirical and thermodynamic models had high consistency with the experimental values. In addition, the m-RK-EOS model had better accuracy than the K-J and S-S models for correlating solubility. Therefore, a calculated solubility can be used to offer basic information for the proper design of supercritical fluid dyeing in industry.