Chapter 5 - Advanced Models: Association Theories and Models

In this chapter, a summary of the most important advanced equations of state to describe phase equilibria and other thermodynamic properties of complex mixtures is presented. A description of the concept of hydrogen-bonding interactions precedes a revision of the most useful association equations used nowadays: the Statistical Associating Fluid Theory (SAFT), including its most successful subsequent versions, and the cubic-plus-association equation. Details on how to implement those approaches and how to parametrize their molecular parameters are also provided. Next, several examples on the performance of these advanced equations for complex systems, including aqueous and gaseous mixtures, and focusing on their application to food engineering, are given. The chapter concludes with a case study devoted to the extraction of olive oil from dried olive using supercritical carbon dioxide. The results highlight the usefulness of these models in order to provide an accurate description of the thermodynamic properties needed for a reliable design in food engineering processes.