Effect of choline chloride/ethylene glycol or glycerol as deep eutectic solvents on the solubility and thermodynamic properties of acetaminophen

Abstract

To overcome low solubility of acetaminophen (ACP), deep eutectic solvents (DESs) based on choline chloride (ChCI) with glycerol (G) and ethylene glycol (EG) as green solvents have been used up to 0.8 mol fraction of DES at T = (298.15 to 313.15) K. Deep eutectic solvents were prepared by combination of the two components with the molar ratios: ChCl/G (1:2) and ChCl/EG (1:2). The solubility of ACP was measured in the aqueous DESs solutions at different temperatures. The solubility in these solvents was increased with increasing the weight fraction of DESs especially in ChCl/EG. The solubility data were correlated by modified Apelblat, Xh (Buchowski), Yalkowsky, NRTL, Wilson and UNIQUAC models. In addition, to study the interactions between the components, the thermodynamic properties including volumetric and compressibility have been investigated using density and speed of sound measurements. Also the thermodynamic functions, Gibbs energy, enthalpy, and entropy of dissolution and mixing were obtained. The solubility data of ChCl/EG is more effective on the ACP solubility rather than the DES containg glycerol. The calculated thermodynamic funtions also confirm the presence of strong solute -solvent interactions between ACP-DESs. The results also show that the main contribution for ACP solubility in the aqueous DES solutions is the enthalpy. (C) 2017 Elsevier B.V. All rights reserved.