Nucleation Kinetics of Ascorbic Acid in Various Aqueous Solvents

The nucleation kinetics of ascorbic acid in water and binary solvent systems of ethanol-water and isopropanol-water have been analyzed by the classical nucleation theory. For that, in total, 3065 data of induction time were collected by the isothermal method at five supersaturations in each solvent system. The induction time data are well represented with the Poisson probability distribution to determine the nucleation rate (J) and growth time (t(g)). The nucleation rate is found to be highest in water (1319.87 m(-3) s(-1)) and decreases with increasing the alcohol composition in the binary solvent systems, showing the minimum nucleation rate (179.24 m(-3) s(-1)) in the isopropanol-water system with a 0.6/0.4 mole fraction ratio. Furthermore, the kinetic parameter (A) decreases, whereas the thermodynamic parameter (B) increases with an increase in the alcohol composition in the aqueous solvent system. The interfacial energy (gamma), critical radius (r(c)), and Gibbs free energy (Delta G(c)) were observed to be high for solvent systems with higher alcohol composition, which indicates a lower interaction between the solute and solution due to high interfacial tension.