Correlation and Prediction of the Solubility of Solid Solutes in Chemically Diverse Supercritical Fluids Based on the Expanded Liquid Theory

Abstract

For the proper design of any extraction procedure based on supercritical solvents, it is essential to have a sound knowledge of the solubility data of different compounds and the accurate way to represent it. The solute's solubility in a supercritical solvent is dependent on the solute, the solvent, and the operating conditions (temperature and pressure). Developing a comprehensive experimental data set is an onerous task and time consuming and, thus, the incentive to develop predictive tools is substantial. In this paper, a technique is presented and tested to correlate and predict solute's solubility in different supercritical fluids with a methodology based on the expanded liquid theory, in which the solid-fluid equilibrium is modeled using the local composition model of UNIQUAC in which the interaction parameters are related to the solvent reduced density with empiric equations. The most advantages of this model include: it does not require the knowledge of critical properties and sublimation pressure of solid solutes and does take into account the binary interaction between solid solute and solvent. The evaluation of the proposed model capabilities is done by testing it on a large data base consisting of experimental solubility data taken from literature of 33 binary systems solid-SC fluid. The results obtained for both correlation and prediction show good agreement with the experimental data used. For the comparison we have considered some literature models that account for effect of the system conditions (temperature and pressure) in addition to the sublimation pressure of the solute through their introduction of the enhancement factor and a model based on a modified Peng-Robinson equation of state.

Supercritical extraction of bioactive compounds from Cocoa husk: study of the main parameters

“…From the overall comparison of the values of AARD, it can be inferred that the proposed models are able to describe the global trend of the experimental data with values that do not exceed a AARD of 12.2%. At the time of predicting the behavior of extraction with SCF, it is common to work with values that are found in an interval of 1% to 30% of AARD [46]. Since, small changes in the independent variables bring big changes in the power of Solvation of the SCF.…”

Solubility of Solids in Supercritical Fluids: The Mendez-Santiago Teja Model Revisited

“…But this is not the case, Mendez-Santiago and Teja [7] utilized Equations (6) and (7) for the same system solid-SC carbon dioxide just for two solutes: eicosanoic acid and myristic acid, and there is a difference of 33% between the AAD% of the two correlations. Also, previous results [9] show considerable differences between correlation utilizing Equations (6) and (7) for many systems among 33 systems solute-SCF considered. In fitting data, it's known that increasing the number of model parameter will generally improve the correlation results, but in the case of Equation (7) the third parameter is not an additional one but it follows from the Clausius-Clapeyron expression.…”

“…In a previous work [9], we have presented a methodology for the correlation and prediction of the solubility of some solids with different functional groups in different supercritical fluids. The methodology is based on the expanded liquid model theory which does not require the knowledge of the solute critical properties and sublimation pressure.…”

Determination of the Solubility of the Repaglinide Drug in Supercritical Carbon Dioxide: Experimental Data and Thermodynamic Modeling

“…One can calculate the solid solution activity coefficient by the UNIQUAC model . When in equilibrium, the fugacity of pure solid and supercritical phases is obtained as follows: …”

“…UNIQUAC (universal quasi-chemical) is an activity coefficient model exploited in explaining phase equilibria. − Nowadays, the model is used for describing the phase equilibrium . It is also been applied by Nasri et al, Álvarez and Aznar, Camy et al, and Chang and Morrell …”