Solid-liquid equilibrium of binary and ternary systems formed by ethyl laurate, ethyl palmitate and n-decane: Experimental data and thermodynamic modeling

The solid-liquid equilibrium phase diagrams of binary and ternary mixtures formed by n-decane and the fatty acid ethyl esters ethyl laurate and ethyl palmitate were studied through differential scanning calorimetry (DSC). Phase change properties of polymorphs were obtained by resolving the thermograms into the corresponding overlapping peaks through a fitting analysis with a Gaussian function. The binary systems show immiscibility in solid phase. The system formed by ethyl laurate and n-decane presents two peritectic transformations, which were also observed in the ternary phase diagram. Equilibrium data were thermodynamically modeled using different models for liquid phase non-ideality and considering different polymorphs in solid phase. The results of modeling are in good agreement with the eutectic behavior of the system formed by ethyl palmitate and n-decane. However, higher discrepancies were observed if no peritectic behavior for the binary system formed by ethyl laurate and n-decane is considered. The results obtained in this work constitute another step forward to enhance the understanding and description of the complex behavior of biodiesel/diesel mixtures at low temperatures.