Computing Liquid-liquid Phase Equilibria: An Exercise to Understand the Nature of False Solutions and How to Avoid Them

Authors

  • María del Mar Olaya University of Alicante
  • Isabel Ibarra University of Alicante
  • Juan A. Reyes-Labarta University of Alicante
  • María Dolores Serrano University of Alicante
  • Antonio Marcilla University of Alicante

Abstract

An exercise to compute LLE data is presented to illustrate the problems that can arise when the isoactivity equilibrium condition is used in the LLE calculations. A much more efficient condition is obtained when isoactivity is combined with the common tangent line criterion, avoiding false solutions that correspond with very low values of the activity objective function. Also, 3D figures are represented to discuss the topological aspects of the dimensionless Gibbs energy of mixture function (GM/RT).

Author Biographies

María del Mar Olaya, University of Alicante

María del Mar Olaya completed her B.S. in chemistry in 1992 and Ph.D. in chemical engineering in 1996. She teaches a wide range of courses from freshman to senior level at the University of Alicante, Spain. Her research interests include phase equilibria calculations and polymer structure, properties, and processing.

Isabel Ibarra, University of Alicante

Isabel Ibarra and Maria Dolores Serrano are recent chemical engineering graduates of the University of Alicante. They are currently postgraduate students, working on different aspects of phase equilibria.

Juan A. Reyes-Labarta, University of Alicante

Juan A. Reyes-Labarta received both his B.S. and Ph.D. in chemical engineering in 1993 and 1998, respectively, at the University of Alic ante (Spain). After post doctoral stays at Carnegie Mellon University (USA) and the Institute of Polymer Science and Tecnology-CSIC (Spain), he is now a full-time lecturer in Separation Processes and Molding Design.

María Dolores Serrano, University of Alicante

Isabel Ibarra and María Dolores Serrano are recent chemical engineering graduates of the University of Alicante. They are currently postgraduate students, working on different aspects of phase equilibria.

Antonio Marcilla, University of Alicante

Antonio Marcilla is a professor of chemical engineering at Alicante University. He has presented courses in Unit Operations, Phase Equilibria and Unit Operations, and Chemical Reactor Laboratories. His research interests are pyrolysis, liquid-liquid extraction, polymers, and rheology. He is also currently involved with the study of polymer recycling via catalytic cracking and the problem of simultaneous correlation of fluid and condensed phase equilibria.

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Published

2007-07-01

Issue

Vol. 41 No. 3 (2007): Summer 2007

Section

Class and Home Problems