Thermodynamic analysis of molecular interactions in binary systems of tert-butanol and hydrocarbon at 298.15 K-318.15 K

The density (ρ) and refractive index (nD) of binary mixtures containing tert-butanol (1) and hydrocarbon (n-hexane, cyclohexane, benzene, ethylbenzene and cumene) (2) were measured at T = 298.15 K to 318.15 K and at 0.1 MPa pressure. The excess molar volume (VmE) and deviation in refractive index (ΔnD) were evaluated and fitted using the Redlich–Kister (RK) equation. The results indicate that the mixture behaviour is influenced by intermolecular interactions, including dipole–dipole forces, hydrogen bonding and dispersive forces, as well as molecular structural characteristics. The variation in VmE was further interpreted using the PFP theory. PFP theory provided a reliable description of both the trend and magnitude of the VmE curves data. The positive values of VmE were observed for all systems at every temperature investigated. In addition, partial (Vˉi), excess partial (VˉiE) and apparent molar volume (Vφi) were derived from the VmE values. The calculated nD data were analysed using different mixing rules.