Liquid–liquid equilibrium of pseudoternary systems containing glycerol + ethanol + ethylic biodiesel from crambe oil (Crambe abyssinica) at T/K = (298.2, 318.2, 338.2) and thermodynamic modeling

In the present work liquid–liquid equilibrium (LLE) data were obtained for systems composed of glycerol + ethanol + distilled fatty acid ethyl esters from crambe oil at T/K = 298.2, 318.2 and 338.2. The experimental data measured for these systems were used to adjust the binary interaction parameters between their components for NRTL model treating the mixture of ester as a single ethyl ester, with the average molar mass of the mixture of esters. Two sets of UNIFAC binary interaction parameters were also tested to predict the LLE of the systems. Ethanol, which is distributed in the glycerol-rich and ester-rich phases, showed a greater affinity to the glycerol rich phase. Glycerol and FAEE presented very low miscibility. The average deviations related to mass fraction composition between experimental and calculated values by the NRTL model were less than 0.82% and by the UNIFAC model were between 2.27% and 3.97%, considering the two different sets of binary interaction parameters.

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► LLE data of glycerol + ethanol + ethylic biodiesel from crambe oil was determined.
► Glycerol and ethylic biodiesel have very low miscibility.
► Ethanol distributes in glycerol-rich and biodiesel-rich phases.
► Estimated parameters of NRTL modeling were representative.
► Necessity of purification in ester-rich phase to biodiesel production was observed.