(387h) Liquid-Liquid Equilibria of Systems Containing Cottonseed Biodiesel + Glycerol + Ethanol At Different Temperatures

Biodiesel presents several characteristics that can be considered as an appropriate alternative fuel in substitution of fossil fuels, e.g., renewable, biodegradable, and relatively clean-burning. According to the last Bulletin of the Brazilian Regulatory Agency (Agência Nacional do Petróleo, Gás Natural e Biocombustíveis - ANP), the most important raw material sources used for the production of biodiesel in Brazil are: soybean seeds (83.26%), followed by bovine fat (12.34%) and cottonseeds (2.17%). Biodiesel consists of a mixture of alkyl esters of fatty acids, generally produced from homogeneous transesterification reactions of vegetable oils and animal fats. Purification process of these transesterification reactions are extremely important in order to provide a biofuel with quality levels required by the international standards specifications. The purification step can be improved by using a liquid–liquid extraction process, generally by using aliphatic alcohols (methanol or more recently ethanol). This study reports LLE experimental data for ternary systems of cottonseed biodiesel + glycerol + ethanol at T = 293.15, 313.15 and 333.15 and atmospheric pressureK. The solubility (binodal) curves and tie-line compositions were obtained by means of density measurements. The reliability of the data has been tested by using Othmer–Tobias equation, with a squared correlation coefficient better than 0.99 for all systems studied. Selectivity and distribution coefficients have been determined from equilibrium data. The Nonrandom Two-Liquid Activity Coefficient Model (NRTL) model was used to predict binary interaction parameters for the biodiesel + glycerol + ethanol system. Root mean square deviations (rmsd) between experimental and calculated compositions in both equilibrium phases were about 0.89% for the system studied.