Molecular-based study of solutions in supercritical solvents

Conference · Thu Sep 01 04:00:00 EDT 1994

OSTI ID:10184682

Shah, V M ^[1]; Lee, L L ^[2]; Cochran, H D ^[3]

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1. Tennessee Univ., Knoxville, TN (United States). Dept. of Chemical Engineering
2. Oklahoma Univ., Norman, OK (United States). School of Chemical Engineering and Materials Science
3. Oak Ridge National Lab., TN (United States)

Behavior and properties of solutions in supercritical (SC) solvents are related to microscopic structures, and the structure and properties of typical attractive SC solutions have been well-studied both experimentally and theoretically. New and interesting properties, however, have been uncovered in recent studies of dilute repulsive and weakly attractive SC solutions. Such repulsive and weakly attractive solutions are encountered in practice when relatively volatile substances are present in a SC solvent. Specific examples of practical importance include organic molecules in SC water and light gases in SC carbon dioxide. We report a study of the microscopic structure and thermodynamic properties of these less-known repulsive and weakly attractive SC mixtures. Results are based on integral equation calculations for model systems and illustrate the qualitative behaviors that may be expected in practice. The results are based on Ornstein-Zernike integral equation calculations in the Percus-Yevick approximation applied to dilute, binary Lennard-Jones mixtures. The microscopic structures calculated (pair correlation functions) are related to the thermodynamic properties through the fluctuation integrals of Kirkwood-Buff theory. Whether the system behaves as a repulsive mixture or a weakly attractive mixture depends on size of solute molecule and strength of its intermolecular attraction relative to the solvent molecule as well as on the temperature and density of the system relative to the critical temperature and density of the solvent.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10184682
• Report Number(s): CONF-9410114--1; ON: DE94019326
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201
CARBON DIOXIDE
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
EQUATIONS
MICROSTRUCTURE
PYRENE
RARE GASES
SOLUTIONS
SUPERCRITICAL STATE
THERMODYNAMICS