Insight into the role of ethylene glycol on thermodynamics and nucleation kinetics of dimethyl terephthalate in mixed solvent system

Dissolution and nucleation are two essential processes for industrial crystallization. This paper investigates the effect of ethylene glycol addition on the crystallization behavior of dimethyl terephthalate (DMT) in solution. The DMT solubility in mixed solvent system (methanol-ethylene glycol) was determined by isothermal satiation approach, and the solubility was associated using seven models. The model fitting results were consistent with the experimental values. Based on the results, the metastable zone width (MSZW) of DMT was detected by the polythermal approach; the modified Sangwal's theory was used to investigate the nucleation behavior, which can provide a new way of thought for better analysis of the crystallization behavior. The results demonstrated that MSZW was associated with various elements, such as cooling rate, saturation temperature and mass fraction of ethylene glycol. The addition of ethylene glycol slowed down the nucleation rate as shown by the broadening of MSZW. We derive the solid-liquid interface energy, the nucleation driving force, the critical nucleation size and the critical Gibbs free energy according to the classical nucleation theory. It is demonstrated that the nucleation driving force and the solid-liquid interface energy are dependent and jointly influence the MSZW. (c) 2023 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.