Effects of Different Solvents on Crystal Nucleation and Growth

Project: National Science and Technology CouncilNational Science and Technology Council Academic Grants

Project Details

Abstract

The choice of solvent in solution crystallization often plays an important role in nucleation, crystal growth, crystal structure, morphology, and size distribution. As both the induction time and the metastable zone width (MSZW) are closely related to the nucleation rate in supersaturated solutions, it is crucial to elucidate how the induction time or the MSZW is influenced by the choice of solvent in understanding nucleation ofa crystallization system. The induction period is defined as the time interval between the creation of the supersaturation and the formation of critical nuclei. MSZW is usually determined by the polythermal method when the solution is continuously cooled at a constant cooling rate. Approximately half of the MSZW is considered as the optimal operating condition in industrial applications. Both MSZW and induction time are importantcharacteristic properties of crystallization for each solute-solvent system. Both MSZW and induction time can vary significantly among different solute-solvent systems and is also affected by the hydrodynamic and operating conditions of the studied system. The solubility of the solute often varies in different solvents. The nucleation and growth rates subsequently also varies in different solvents. In this three-year proposal, effects of different solvents on crystal nucleation and growth will be studied. In the first year, a batch experimental set-up is designed to study the effects of different solvents, including methanol, ethanol, 1-propanol, 1-butanol, acetic acid, ethyl acetate, acetonitrile, acetone and toluene, on the nucleation rate in terms of the induction time and MSZW for three crystallization systems, including salicylamide, salicylic acid and risperidone. The resulting crystals are analyzed by X-ray diffraction (XRD) and Raman spectroscopy. We will develop a model based on classical nucleation theory to investigate the effects of different solvents on the pre-exponential factor and interfacial energy for three crystallization systems. The obtained results will be analyzed to elucidate how the interaction between the solute molecule and solvent molecule in different solvents affects the pre-exponential factor and interfacial energy for three crystallization systems. In the second year, a photomicroscopic experimental set-up is designed to study the effects of different solvents, including methanol, ethanol, 1-propanol, 1-butanol, acetic acid, ethyl acetate, acetonitrile, acetone and toluene, on the growth rate for three crystallization systems, including salicylamide, salicylic acid and risperidone. We will develop a model based on two-step growth model to investigate the effects of different solvents on the growth kinetics for three crystallization systems. The obtained results will be analyzed to elucidate how the interaction between the solute molecule and solvent molecule in different solvents affects the growth kinetics for three crystallization systems. In the third year, the effects of various impurities on the nucleation and growth kinetics in different solvents, including methanol, ethanol, 1-propanol, 1-butanol, acetic acid, ethyl acetate, acetonitrile, acetone and toluene, will be studied for three crystallization systems, including salicylamide, salicylic acid and risperidone. Based on the obtained results, the previous models proposed for crystal nucleation and growth will be modified to incorporate the influence of various impurities on the nucleation and growth kinetics for three crystallization systems.

Project IDs

Project ID:PB10708-2758
External Project ID:MOST107-2221-E182-031
StatusFinished
Effective start/end date01/08/1831/07/19

Keywords

  • nucleation
  • crystallization
  • solvent
  • induction period
  • metastable zonewidth
  • polymorph

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