Thermophysical properties of eutectic mixtures composed by oleic acid and components of essential oils

Currently, replacing traditional solvents with others whose components are considered safe is one of the most important challenges in the chemical industry. However, this change cannot be achieved without understanding the behavior of fluids under different operating conditions. To achieve this, thermophysical properties must be either determined experimentally over wide ranges of pressure, temperature, and composition, or tools must be available to predict them. Here, we studied binary mixtures of Generally Recognize as Safe (GRAS) compounds. These mixtures could be used both as extractants of natural products and solvents of poorly-water soluble ones. Specifically, they are oleic acid-based systems with thymol, l-menthol, eugenol, or linalool. The measured properties were the phase change equilibria, density, speed of sound, refractive index, isobaric molar heat capacity, surface tension, and kinematic viscosity at 0.1 MPa and from 283.15 to 338.15 K. In addition, several derived properties were calculated, different correlations were used and the PC-SAFT equation of state (EoS) was validated. All mixtures were less dense than water and moderately viscous. The most and least compact mixtures were those with eugenol and linalool, respectively. The prediction of the isobaric molar heat capacity from both molar mass and critical properties, as well as EoS, showed a deviation of less than 5 % from the measured values. For the density, the maximum mean relative deviation with the EoS results was of 0.19 %.