Thermophysical behaviour and modeling of properties in (ethyl lactate + dimethyl succinate) binary mixtures at different temperatures

Experimental measurements in the temperature range of 303.15–318.15 K were carried out to determine the ultrasonic velocity, density, and refractive index of the binary mixtures of ethyl lactate and dimethyl succinate. To assess the characteristics and types of intermolecular interactions prevalent that occur during mixing, excess thermodynamic properties (VmE, κsE, Ks,mE, uE, αpE) and deviation in optical properties (Δϕn) are calculated and fitted to a Redlich-Kister (R-K) type polynomial equation. For binary mixtures of chosen configurations and corresponding pure components, FTIR analysis was carried out to gather information about the structural changes occurring during mixing. Additionally, refractive index data was utilised to examine the viability of various mixing rules by Arago-Biot, Eykman, Eyring-John, Gladstone-Dale, Heller, Lorentz-Lorenz, Newton, Oster and Wiener. Density and excess molar volume of ethyl lactate + dimethyl succinate mixture was modelled using PC-SAFT in the temperature range of 303.15 K to 318.15 K and atmospheric pressure of 0.1 MPa. The approach used is purely predictive in binary mixtures, i.e., without using adjustable parameters, a correct qualitative representation of the experimental data is provided.