Correlation of the solubility of low-volatile organic compounds in near and supercritical fluids Part II. Applications to Disperse Red 60 and two disubstituted anthraquinones

In this paper. we combine experimental investigations and a newly developed correlation to elucidate the high-pressure solubility behavior in CO2 and the saturation pressure of three anthraquinone-based disperse dyestuffs. For modeling pVT-data of the supercritical solvent CO2, an accurate semiempirical equation of state has been developed. Furthermore, this equation of state has been extended to dilute solutions of the low-volatile anthraquinone derivatives by adapting a fugacity approach. The required saturation pressure of the pure solute has been described by a Clausius-Clapeyron type equation with two adjustable parameters. We have compared the saturation pressures deduced from the sequence of solubility isotherms with those reported in the literature. Besides, the consequences of the choice of saturation pressure on our calculations, especially on the coordinates of solubility extremes, are discussed. The results from our model demonstrate a substantial agreement between measured and calculated solubility data, even for a large solvent density region in its entirety. (C) 2002 Elsevier Science B.V. All rights reserved.