Thermodynamics of mixtures containing polycyclic aromatic hydrocarbons

The DISQUAC group contribution model has been applied to the study of mixtures containing a polycyclic aromatic compound, naphthalene, phenanthrene, anthracene or pyrene, and an organic solvent, n-alkane, cyclohexane or 1-alkanol. The corresponding interaction parameters are reported. Systems with alkanes are characterized by dispersive parameters only. For naphthalene + 1-alkanol mixtures, the aromatic/OH contacts are represented by dispersive and quasichemical parameters. The latter are equal to those encountered in 1-alkanol + benzene, or + alkylbenzene mixtures for such contacts. DISQUAC provides good results on molar excess enthalpies, HE, solid-liquid equilibria, SLE, and vapor-liquid equilibria over a wide range of temperature for the investigated mixtures. In PAH + n-alkane systems, there is an enthalpy-entropy compensation effect in solutions with long alkanes, and no Patterson's effect is observed. Solubility of naphthalene in hexane or 1-hexanol is similar, and lower than that of 1-alkanol in alkane. This seems to indicate that interactions between unlike molecules are not so relevant as in 1-alkanol + benzene mixtures.