A new UNIFAC parameterization for the prediction of liquid-liquid equilibrium of biodiesel systems

Author(s)

Bessa, Larissa C. B. A. ; Ferreira, Marcela C. ; Abreu, Charlles R. A. ; Batista, Eduardo A. C. ; Meirelles, Antonio J. A.

• Document type: Journal article
• Source: Fluid Phase Equilibria; v. 425, p. 98-107, OCT 15 2016.
• Web of Science Citations: 13

Abstract

The environmental adversities and the global concern about the conservation of non-renewable natural resources have stimulated a search for environmentally friendly energy sources. In this context, biodiesel has emerged as an important alternative to replace fossil fuels, due to its renewability, non-toxicity and biodegradability. Modeling, simulation and design of unit operations involved in the production of edible oils and biodiesel require knowledge of phase equilibrium. Several versions of the UNIFAC model are frequently used for process design when experimental determination of phase equilibrium data is difficult or time-consuming. In this work, the original UNIFAC model parameters are first checked for their predictive capability and then modified in terms of new readjusted binary interaction parameters. It was noted that the UNIFAC model without any changes in its parameters results in inadequate predictions. Thus, in order to obtain a good predictive tool, a comprehensive liquid-liquid equilibrium data bank of systems present in biodiesel production was organized and new UNIFAC interaction parameters were adjusted. At first, the molecules were divided into UNIFAC traditional structural groups. However, this first approach resulted in poor prediction, probably as a consequence of the strongly polar hydroxyl groups bonded to the consecutive carbon atoms of glycerol and acylglycerol molecules. Thus, a new group ('OHgly') was introduced and two matrices of parameters were adjusted. In general, satisfactory predictions were obtained and a significant improvement in the ``performance of this group contribution model has been achieved. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 09/54137-1 - Acquisition of a particle size/distribution analyzer, a zeta potential measurement system, a spray dryer, and an ultra-high-pressure liquid chromatograph/mass spectrometer
• Grantee: Miriam Dupas Hubinger
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 08/56258-8 - Phase equilibrium and purification processes in the production of biofuels and biocompounds
• Grantee: Antonio José de Almeida Meirelles
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Thematic Grants