Linear free energy relationship analysis of the solubility of solids in supercritical CO₂

Abstract

Linear free energy relationship (LFER) methods were used to construct a model for the solubility of a species in supercritical CO2. The final model was based on 64 molecules and 782 data points, employing a modified version of the Abraham LFER equation incorporating π1, the dipolarity/polarizability of the CO2 at a given density. This allowed us to model data ranging from 308 to 435 K and 74.3 to 410 bar, with an accuracy of ±0.65 log mole fraction units. The model shows that solubility in supercritical CO2 is favoured by the presence of π and n electron pairs and hydrogen‐bond basicity. Solute size and hydrogen‐bond acidity are less important, whereas polarity/polarizability is statistically insignificant. Copyright © 2001 John Wiley & Sons, Ltd.

Modeling of diffusivities in supercritical carbon dioxide using a linear solvation energy relationship

“…For example, the aromatic solute sc-CO 2 solubility model of Famini and Wilson [10] had an R and S.D. value of 0.928 and 0.477, whereas the large database of Saunders and Platts [12] had an R 2 and S.D. value of 0.782 and 0.659, respectively.…”

“…The values of other solvent descriptors (hydrogen-bond acidity, hydrogen-bond basicity) of CO 2 are constant over the gas-to-liquid density range as measured by UV-vis solvatochromic methods [15]. Therefore, following other researcher [8,12,16], an additional solvent term was used for the LSER equation in this work. The following LSER (Eq.…”

“…The prediction accuracy of LSER models is modest, with the case of solid solubilities in sc-CO2 reported by Saunders and Platts [12] being on the order of ±0.65 log mole fraction units and the solubility model of Bush and Eckert [9] having an average error of about 65%. However, LSER models have prospects of improving as the experimental database becomes larger and as theoretical methods are applied.…”

“…Famini and Wilson [10,11] developed a theoretical LSER (TLSER) in which computed molecular properties were used for each of the property descriptors to predict the solubilities of aromatic compounds in sc-CO 2 . Saunders and Platts [12] constructed an empirical LSER model for solid solubilities in sc-CO 2 for 64 molecules using 782 data.…”