Liquid-liquid equilibrium data for systems important in biodiesel production, involving vegetable oils + ethyl esters + monoacylglycerols and diacylglycerols + anhydrous ethanol, at 303.15 and 318.15 K

In biodiesel production from vegetable oils, mono- and diacylglycerols are intermediate compounds of transesterification reaction of triacylglycerols with short chain alcohols, and may contaminate the final product, when the fatty ester conversion is not complete. Thus, this study aims to determine the liquid-liquid equilibrium data of systems important to biodiesel production, containing triacylglycerols (TAG) of refined oils (soybean, cottonseed and rice bran) + commercial mixture of fatty acid ethyl esters (linoleate and oleate) + diacylglycerols (DAG) + monoacylglycerols (MAG) of commercial mixture of partial acylglycerols + anhydrous ethanol at (303.15 and 318.15 K). The High Performance Size Exclusion Chromatography (HPSEC) method was used for quantification of all components: TAG, DAG, MAG, fatty acid ethyl esters and ethanol in both phases in equilibrium. The preference of fatty acid ethyl esters and DAG for the oil phase is consistent with the reported data in literature. The mass fraction of MAG was greater in the solvent phase. The average deviation between experimental and calculated compositions, using NRTL model, was less than 0.60%. Using the original version of UNIFAC model with two different set of parameters, the deviations varied within the range of (4.25-11.45)%.