Vapour pressure and VLE data of fatty compounds

Abstract

Knowledge of physical and thermodynamic properties of pure compounds and their mixtures enables the design and optimization of industrial processes. However, these experimental data obtained by conventional techniques might be uneconomical, especially because of the high cost of some pure chemicals and the requirement of large amount of reagents (50 mL–200 mL). Another difficulty of conventional techniques is in obtaining low vapour pressure data. The Differential Scanning Calorimetry (DSC) technique has been used as an alternative method to obtain vapour pressure and VLE data due to the advantages of a lower operating time. Therefore, the purpose of this work has been extending the methodology already used from saturated fatty compounds to unsaturated fatty compounds. However, improvements in the DSC technique were necessary to evaluate experimental vapour pressure data at low pressures (2.67–26.66 kPa) for this class of compounds, such as: linoleic acid and linoleic acid methyl ester and related mixtures. Experimental assays resulted in a maximum standard deviation of ± 0.86 K in relation to the saturation temperature. All analyses were performed in triplicate and the vapour pressure data have been modeled by the Antoine equation. The thermodynamic modelling of the experimental VLE data allowed the determination of binary interaction parameters for the UNIQUAC and NRTL models used to describe the non-ideality of the liquid phase.