Increasing the Prediction Efficiency of Hansen Solubility Parameters in Supercritical Fluids

Abstract

This work describes a simplified method developed for calculating the Hansen parameters (HSPs) for scCO2-polar modifier solvent mixtures. The method consists in fitting 2nd order equations on the calculated values of HSPs of pure components in function of pressure and temperature. It has been proved that these equations are suitable for the characterization of the above system. The current work also proposes a modified representation method, which eliminates the shortcomings of the original ternary Teas diagram, normally used for the representation of the Hansen parameters. On the one hand, the Teas diagram uses quantities without any physical meaning and, on the other hand, the illustration of the solubility information is distorted because it does not take into account the differences of the Hildebrand parameters of different solvents. The factors we have chosen to represent on the ternary diagram possess physical meaning (cohesion energy density partitions). The distortion was eliminated by extending the Teas diagram to a prismatic three dimensional representation. We proved that the Hansen-ellipsoid from the Cartesian coordinate system (dd = f (δH, dp)) is transformed in an ellipsoid also in the new coordinate system (the transformation is pseudo-isomorphic). Nonetheless, the suggested corrections improve the accuracy of the Hansen method, in some cases the interactions between the solvents and the dissolved materials are still not predicted with sufficient accuracy. Most probably a thermodynamic-based correction of the values of the HSPs of small molecules could lead to a significant improvement of the predictive ability of the newly developed method.

Study of Antioxidant Activity of Garden Blackberries (Rubus fruticosus L.) Extracts Obtained with Different Extraction Solvents

“…The Hansen solubility parameters (HSP) of solvent mixtures differ from pure solvents. Still, they could be the volumetric fraction-weighted average of the components' HSPs, even for solvents in a supercritical state, as seen in Equation ( 9) [50].…”

“…For extractions at a higher temperature, such as Soxhlet and, especially, for pressurized liquid extraction (PLE), the Hansen parameters should be calculated, taking into account the temperature dependence of these parameters [50,51].…”

“…From Figure 6, we obtained data that, for the extraction of cyanidin-3-O-glucoside, predicted the optimal theoretical concentration of acetonitrile-water mixture will be copt = 56.2% v/v, which is in good agreement with the previous estimation. For extractions at a higher temperature, such as Soxhlet and, especially, for pressurized liquid extraction (PLE), the Hansen parameters should be calculated, taking into account the temperature dependence of these parameters [50,51].…”

Preface

“…Practical solutions are presented on the application methodology of solubility parameters for cosolvent systems and expanded liquids. [4,5] The expanded liquids play key role in all gas antisolvent processes, which can be used for diastereomeric salt based chiral resolution as well. [6] A special case of diastereomeric salt formation based chiral resolution is described by Lőrincz et al, where novel resolving agents are formed with CO2.…”