Thermodynamic solubility and solvation behavior of ferulic acid in different (PEG-400 + water) binary solvent mixtures

This work was carried out to determine solubility, solution thermodynamics, solvation behavior, and molecular interactions of a natural compound ferulic acid (FLA) in different ‘[polyethylene glycol-400 (PEG-400) + water]’ binary solvent mixtures at ‘T?=?298.2 K to 318.2?K’ and ‘p?=?0.1?MPa.’ The mole fraction solubilities (x_e) of FLA were determined by liquid chromatographic technique using a static equilibrium technique. The obtained solubility data of FLA were regressed using ‘Van’t Hoff, Apelblat, Yalkowsky-Roseman and Jouyban-Acree models.’ The solubility of FLA (expressed in mole fraction) was enhanced with elevation in absolute temperature in each ‘PEG-400?+?water’ binary solvent mixture evaluated. The maximum x_e values of FLA were recorded in neat PEG-400 (1.94?×?10^?1) at ‘T?=?318.2 K.’ While, the minimum one was obtained in neat water (4.90?×?10^?5) at ‘T?=?298.2 K.’ The molecular interactions between FLA-PEG-400 and FLA-water were obtained by determination of activity coefficients of FLA in different ‘PEG-400?+?water’ binary solvent mixtures. The physical data of activity coefficients recorded in this work suggested strong molecular interactions in FLA-PEG-400 in comparison with FLA-water. ‘Apparent thermodynamic analysis’ suggested an ‘endothermic and entropy-driven dissolution’ of FLA in each ‘PEG-400?+?water’ binary solvent mixture investigated.     

Prediction of solubility of long-chain hydrocarbons in various solvents using UNIFAC

The UNIFAC group contribution model has been widely used in the prediction of phase equilibria of various fluid mixtures. We have applied the method to predict the solubility of various long-chain hydrocarbon solids in a number of solvents of industrial importance. The calculated solubilities are compared with measured values and also with the predictions of the regular solution theory of Hildebrand and Scatchard. Some disagreements were found between the measured solubilities and the predicted values of both theories. Overall the UNIFAC scheme appears to be superior to the regular solution theory.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.