Near-critical and supercritical dilute solutions viewed from macroscopic and molecular-scale perspectives

• Published in: The Journal of supercritical fluids 2010-12, Vol.55 (2), p.472-478
• Main Authors: Fernández-Prini, R., Laura Japas, M., Marceca, Ernesto
• Format: Article
• Language: English
• Subjects: Availability; Critical behaviour; Density; Dilution; Exploration; Fluctuation; Infinity; Intermolecular interactions; Krichevskii's function; Near-critical solvents; Solvation; Solvents
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2010.10.009

Partial molar properties of dilute solutes in near-critical solvents exhibit a strong dependence on temperature and density which hinders the description of their behaviour under those conditions. We used the well-behaved Krichevskii function, J = ( dp/ dx) V,T supra infinity, to describe that region of the thermodynamic space, and have extended its use to ternary solutions (two solutes + one near-critical solvent) successfully. The use of supercritical solvents permits a controlled and continuous exploration of the density dependence of solutes’ properties without undergoing phase transitions, hence the availability of a non-diverging property like J to describe the systems is greatly important. We show its application for binary and ternary systems that have been studied and also give some information about the molecular structure of near-critical solutions. This knowledge provides a better understanding about solvation and its dependence on long-range (critical) fluctuations in the presence of intermolecular interactions.