The effect of 1-hexyl-3-methylimidazolium bromide ionic liquid as a co-solvent on the aqueous solubility of lamotrigine at T = (293.2-313.2) K

The solubility of lamotrigine in the aqueous mixtures of 1-hexyl-3-methylimidazolium bromide [HMIm] [Br] were determined up to 0.8 mass fraction of [HMIm][Br] at several temperatures T= (293.2 to 313.2) K. The lambda-h and van't Hoff models with temperature dependency and Jouyban-Acree-van't Hoff, e-NRTL, UNIQUAC and Wilson models with temperature and solvent composition dependency were used to correlate the experimental solubility data. The overall %ARD value using the van't Hoff model is lower than the lambda-h equation. Moreover, the obtained %ARDs show that the Jouyban-Acree-van't Hoff and UNIQUAC models have the best consistency with the experimental solubility data, and the order of %ARDs for these models are UNIQUAC < Jouyban-Acree-van't Hoff < e-NRTL < Wilson. Moreover, the thermodynamic functions, apparent Gibbs energy, enthalpy and entropy of dissolution and mixing were calculated based on the van't Hoff equation. The results obtained from thermodynamic functions indicating the strong soluteco-solvent interactions between LTG and [HMIm][Br] and also suggest that enthalpy has the main contribution to the dissolution process of this drug in the aqueous ionic liquid mixtures. (C) 2019 Elsevier Ltd.