Liquid–Liquid Equilibrium Measurement and Thermodynamic Modeling of the {Sterculia striata Biodiesel + Glycerol + Ethanol} System

Abstract

This paper reports experimental results and thermodynamic modeling of the liquid–liquid equilibrium (LLE) of the system chicha biodiesel (Sterculia striata) + glycerol + ethanol. Binodal curves and tie lines were obtained at different temperatures (303.15, 318.15, and 333.15 K) and atmospheric pressure (101.3 kPa). The quality of the experimental data was evaluated using the criteria of Marcilla and co-workers. The nonrandom two-liquid (NRTL) and analytical solutions of groups (ASOG) models were used to correlate the LLE data. Both models well fitted the experimental data with root-mean-square deviations (rmsd) not greater than 1.5%.

Thermodynamic Modeling of Liquid-Liquid Equilibrium in Ternary Systems with Biodiesel and Isolated Ester (Methyl Palmitate)

“…This low miscibility is attributed to the fact that the polar molecules methanol and glycerol show no affinity for biodiesel because it is a mixture of nonpolar substances. This behavior was also observed in the Sterculia striata biodiesel + glycerol + ethanol [37] and soybean FAME + water + glycerol systems [17]. Analogously, the tie lines obtained here are similar in both systems, and their slopes demonstrate that methyl alcohol solubility in the biodiesel-rich (Figure 2a) and MP-rich phase (Figure 2b) is lower than in the glycerol-rich phase, indicating that a small amount of methanol and glycerol needs to be removed in the FAME-rich phase during biodiesel production via fatty acid esterification with methanol.…”