Measurement and correlation on solubility of acetaminophen in aqueous solutions of 1-octyl-3-methyl imidazolium bromide, 1-butyl-4-methyl pyridinium bromide and 1-octyl-4-methyl pyridinium bromide

Aqueous solubility of acetaminophen in the presence of 1-octyl-3-methyl imidazolium bromide, 1-butyl4-methyl pyridinium bromide and 1-octyl-4-methyl pyridinium bromide ionic liquid, as co-solvent was investigated at different temperatures and mass fraction of ionic liquid. The obtained results reveal that the solubility of acetaminophen was increased by increasing temperature and concentration of ionic liquid. Solubility of ACP was significantly increased when mass fraction of 1-octyl-3-methyl imidazolium bromide and 1-octyl-4-methyl pyridinium bromide reaches to more than 0.05. The possible reasons behind enhanced solubility of ACP in aqueous solution of ionic liquid are hydrophobic interaction and the formed micelles by cations of ionic liquid. Thermodynamic functions of dissolution were calculated by Van't Hoff equation. The experimental solubility of acetaminophen was correlated with the modified Wilson and the electrolyte-NRTL models as activity coefficient model. (C) 2020 Elsevier Ltd.