Study and mathematical modeling of caffeine solubility in N-methyl-2-pyrrolidone + ethylene glycol mixture at different temperatures

Abstract The present work is devoted to the study of the caffeine dissolution process in the non-aqueous binary mixture of N-methyl-2-pyrrolidone + ethylene glycol mixture at a temperature range of T = (293.2 – 313.2) K. The generated solubility data are mathematically represented by using some cosolvency models (i.e. Jouyban-Acree, Jouyban-Acree-van’t Hoff, mixture response surface and the double log–log) and their accuracy is investigated by calculation of the mean relative deviations (MRD%) for back-calculated solubility data. The density values of caffeine saturated solutions are determined and represented by the Jouyban-Acree model. In another effort, the apparent thermodynamic properties of Gibbs free energy, standard enthalpy, and entropy of the dissolution process are computed using the Gibbs and van’t Hoff equations at Thm = 303.0 K and discussed.