THE SOLUBILITY OF SOLIDS IN COMPRESSED GASES

The density series virial equation of state truncated at the third vir ial coefficient has been evaluated for describing the fluid nonidealit y of systems of pure solids in equilibrium with near-critical CO2 incl uding systems with cosolvents. The function [In (z phi(1))]/rho is fou nd to be linear with rho for pressures up to 400 bar for 16 solutes, e leven of which also involved 8 different cosolvents for temperatures f rom 300 to 523 K. As required, when the virial series is applicable, t he zero-density intercepts obtained from high-pressure data agree with those from low-pressure data. The method shows how cosolvent contribu tions via composition and density can be explicitly separated. Predict ion of second cross virial coefficients along with fitting the third v irial to a single data point on the isotherm can be at least as succes sful as other models. Sensitivity to variations in sublimation pressur e, solid molar volume, and fluid density has been tested.