THE SOLUBILITY OF SOLIDS IN COMPRESSED GASES

The density series virial equation of state truncated at the third virial coefficient has been evaluated for describing the fluid nonideality of systems of pure solids in equilibrium with near-critical CO2 including systems with cosolvents. The function [In (z phi(1))]/rho is found to be linear with rho for pressures up to 400 bar for 16 solutes, eleven of which also involved 8 different cosolvents for temperatures from 300 to 523 K. As required, when the virial series is applicable, the zero-density intercepts obtained from high-pressure data agree with those from low-pressure data. The method shows how cosolvent contributions via composition and density can be explicitly separated. Prediction of second cross virial coefficients along with fitting the third virial to a single data point on the isotherm can be at least as successful as other models. Sensitivity to variations in sublimation pressure, solid molar volume, and fluid density has been tested.