Liquid–Liquid Equilibria of Glycerol + Alcohol + Safflower Biodiesel Systems: Measurement and Modeling

Liquid–liquid equilibrium (LLE) for the biodiesel + glycerol + alcohol system is essential for the design, operation, process optimization, and economic evaluation of a biodiesel production plant. In this work, methyl and ethyl safflower biodiesels were produced from safflower (Carthamus tinctorius L.) seed oil. New LLE experimental datasets were obtained for the glycerol (1) + methanol/ethanol (2) + methyl/ethyl safflower biodiesel (3) systems at 298.15 and 318.15 K under atmospheric pressure. Binodal curves, tie-lines, distribution coefficients, and selectivity were determined. Data reliability was confirmed using the Othmer–Tobias correlation. LLE data were correlated with the UNIQUAC model satisfactorily, with deviations between 0.70 and 2.79% for all studied systems. The consistency of the estimated binary interaction parameters of the UNIQUAC model was ascertained. Finally, through process simulations in Aspen Hysys software, it was verified that the UNIFAC LLE model, along with the UNIQUAC model, can also be used adequately to describe the liquid–liquid behavior of biodiesel separators, provided that the biodiesel composition is accurately known.