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 (xe) 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 xe 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.