Quartz crystal microbalance technique for analysis of cooling crystallization

Area of Science:

• Chemical Engineering
• Materials Science
• Physical Chemistry

Background:

• Crystallization processes are crucial in chemical and pharmaceutical industries.
• Conventional methods for analyzing crystallization often focus on single phases (solid or solution).
• In situ monitoring of crystal nucleation and growth remains challenging.

Purpose of the Study:

• To develop and validate a quartz crystal microbalance (QCM) technique for in situ analysis of cooling crystallization.
• To simultaneously monitor changes in both solid and solution phases during crystallization.
• To extract mechanistic information about crystal nucleation and growth.

Main Methods:

• Utilizing a quartz crystal microbalance (QCM) to measure resonant frequency and resistance changes.
• Simultaneously analyzing solid mass and liquid viscosity variations.
• Employing a resonant frequency-resistance (F-R) plot to interpret crystallization dynamics under varying cooling conditions.

Main Results:

• QCM responses reflect initial solution viscosity increases during cooling.
• Sharp changes in QCM responses indicate the induction point of crystal nucleation.
• Accurate measurement of the induction point and metastable zone width was achieved.
• Mechanistic insights into molecular cluster formation, nucleation, and growth were obtained from F-R plots.

Conclusions:

• The developed QCM technique offers a powerful tool for in situ analysis of cooling crystallization.
• Simultaneous monitoring of solid and solution phases provides comprehensive understanding of crystallization processes.
• The technique enables accurate determination of key crystallization parameters and mechanistic insights.