Thermodynamics of molecular interaction of ternary mixture containing ethanol, n-heptane and n-octane at 298.15, 308.15 and 318.15 K

Abstract

In this research article, densities (ρ), speeds of sound (u) and refractive indices (n) of the ternary liquid mixture of oxygenated fuel additive (ethanol) and aliphatic hydrocarbons (C7, C8) were experimentally measured at different temperatures (T = 298.15 K to 318.15 K) and pressure of 0.1 MPa over whole composition range. Excess molar volume (VmE), excess ultrasound speed (uE), excess isentropic compressibility (ksE), excess intermolecular free length (LfE), excess available volume (VaE) and deviation in refractive index (Δn) of the ternary mixture were evaluated using experimental data. The VmE values were fitted to the Singh, Nagata and Cibulka equations and also interpreted using Prigogine-Flory-Patterson (PFP) theory. Various geometrical solution models like Tsao-Smith model, Kohler model, Rastogi model, Jacob-Fitzner model, and Radojkovic model were used to predict VmE values. The uE, ksE, LfE, VaE and Δn values were also fitted to the Singh equation. Various correlations and mixing rules were used for theoretical prediction of u and n values. Temperature effects on various thermodynamic properties were also studied. The values of VmE, uE, ksE, LfE, VaE and Δn were interpreted in terms of molecular interactions in between the fuel additive and hydrocarbons.