Solubility modeling of solids in supercritical fluids using the Kirkwood-Buff fluctuation integral with the hard-sphere expansion (RISE) theory

Kirkwood-Buff integrals for hard-core Yukawa fluids

The Kirkwood-Buff (KB) theory of solution is employed to investigate several macroscopic properties of the one-component hard-core Yukawa (HCY) fluid, where the key physical quantities are the KB integrals (KBIs). For both repulsive and attractive HCY fluids, the radial distribution functions are calculated by using the classical density functional theory, and then the corresponding KBIs are carried out. Since the local structure and global properties of a fluid can be related by KBI, we presented the isothermal compressibility and the derivative of the chemical potential with respect to bulk density for both repulsive and attractive HCY fluids. It is found that a transition of the affinity of particles in an attractive HCY fluid exists. The corresponding phase diagrams on the affinity are illustrated, which consist of repulsive and attractive regions with the boundary line of KBIs being zero. These results show that the aggregated structure of a HCY fluid can be effectively regulated by the screening parameter, bulk density and interaction energy, while KBIs can provide a quantitative reliable description on the properties of HCY fluids.

Solubility prediction in supercritical CO(2) using minimum number of experiments

The correlation ability and solubility prediction in supercritical carbon dioxide of a proposed equation were studied. The work involved the solubilities of nicotinic acid and p-acetoxyacetanilide in supercritical carbon dioxide using a dynamic flow solubility system at 35-75 degrees C and 100-200 bar. The generated experimental solubility data together with 21 data sets collected from the literature were used to evaluate the correlation ability of available empirical equations. The average absolute relative deviations (AARD) for the empirical equations are 12.6-24.8%. The prediction capability of the modified empirical relationship was studied with six experimental data points as a training set. Then, solubility at other temperatures and pressures were predicted. The AARD between predicted solubilities and observed values is 17%.