Thermodynamic interactions and characterisation of naphthenic oil by inverse gas chromatography

Abstract

The thermodynamic properties of naphthenic oil, a plasticiser, were investigated by means of inverse gas chromatography (IGC) using 10 different kinds of solvents as probes. Some thermodynamic parameters, such as specific retention volume, weight fraction activity coefficient, Flory–Huggins interaction parameter, partial molar heats of mixing and solubility parameter were obtained to judge the interactions between oil and solvents and the solubility of oil in these solvents. The results indicated that n-heptane, n-hexane, cyclohexane, chloroform, benzene and diethyl ether are good solvents for oil at experimental temperatures. The solubility parameters of oil varied from 13.94 to 13.21 (J cm−3)1/2 at temperature range 323–353 K. The solubility parameter of oil was calculated to be 14.38 (J cm−3)1/2 at room temperature, which is consistent with that obtained using surface tension–solubility parameter relation method.