Phase equilibria and thermophysical properties of carbon dioxide-expanded fluorinated solvents

The volume expansion behavior and liquid molar compositions of several fluorinated solvents (methoxynonafluorobutane, C₄F₉OCH₃; ethoxynonafluorobutane, C₄F₉OC₂H₅; 1,1,1,2,3,4,4,5,5,5-decafluoropentane, C₅F₁₀H₂; and perfluorohexane, C₆F₁₄) expanded by pressurized carbon dioxide were measured at temperatures of 298 and 308K and pressures up to 72bar. The densities and viscosities of the expanded liquid phases were also determined. Fluorinated solvents undergo greater solvent-dependent volume expansion (as defined by de la Fuente Badilla et al. [J. Supercrit. Fluids 17 (2000) 13]) relative to traditional organic solvents. The Peng-Robinson equation of state (PR-EOS) satisfactorily described the liquid phase composition of the expanded fluorinated solvents. The viscosity reduction of the expanded fluorinated solvents was modeled by extending the method of Orbey and Sandler [Can. J. Chem. Eng. 71 (1993) 437] to fluorinated solvents. The model predicted the viscosities of the CO₂-expanded solvents with an absolute average relative deviation (%AARD) of 6-12%.