Solubility of sulfadiazine in (ethylene glycol plus water) mixtures: Measurement, correlation, thermodynamics and preferential solvation

The equilibrium solubility of sulfadiazine (SD) in (ethylene glycol (EG) (1) + water (2)) mixtures at temperatures from (278.15 to 318.15) K is reported. Mole fraction solubility of SD (x(3)) increases with temperature arising and also increases with the EG proportion increasing. It varies from 4.81 x 10(-6) in neat water to 532 x 10(-4) in neat EG at 298.15 K. Solubility behavior was correlated by the extended log-linear model of Yalkowsky, the Jouyban-Acree model, and Jouyban-Acree-van't Hoff model and the obtained mean percentage deviations are 43.6%, 7.0% and 7.1%, respectively. From the variation of solubility with temperature the apparent thermodynamic analysis of dissolution and mixing was performed in all the mixtures and neat solvents. Based on the inverse Kirkwood-Buff integrals (IKBI) is observed that SD is preferentially solvated by water in water-rich mixtures (0.00 < x(1) < 0.24) but preferentially solvated by EG in the interval (0.24 < x(1) < 1.00). (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study reports the equilibrium solubility of sulfadiazine (SD) in (ethylene glycol (EG) + water) mixtures at different temperatures. The solubility of SD was found to increase with temperature and with higher proportions of EG. Various models were used to correlate the solubility behavior, and thermodynamic analysis was performed to study the solvation of SD in different mixtures. It was observed that the solvation preference of SD changes between being solvated by water and EG in different mixture compositions.