Quantifying ultrasound for sono-crystallization

Forbes, Clarissa and Price, Chris and O'Leary, Richard; (2019) Quantifying ultrasound for sono-crystallization. In: 2019 IEEE International Ultrasonics Symposium (IUS). IEEE International Ultrasonics Symposium (IUS) . IEEE, GBR. ISBN 978-1-7281-4596-9 (https://doi.org/10.1109/ULTSYM.2019.8926000)

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The application of ultrasound to crystallization processes is a well-established technique employed to control the initiation of nucleation and therefore to achieve control over the crystal size and size distribution. In the context of Apfel’s golden rules of cavitation: "Know thy liquid," "Know thy sound field" and "Know when something happens," the third rule has been satisfied. However, in order to link the applied ultrasonic energy to the enhanced process parameters, it is important to characterize the sound field and cavitation activity in the crystallization solvent. In order to better understand and design sono-crystallization experiments in the context of pharmaceutical manufacturing, measurements of acoustic emissions, broadband integrated voltage and focused beam reflectance measurements (FBRM) have been carried out in five typical crystallization solvents and water at a fundamental frequency of 40 kHz. The approaches taken have been to detect and measure cavitation activity as a function of ultrasonic power, allowing a comparison across the solvents.