Modeling solution concentration in cooling crystallization using an ultrasonic probe and image monitoring

Abstract

Supersaturation during the crystallization process has been a primary focus of research for many years. The ability to measure solution concentration in situ is essential for improving our understanding and control of crystallization. In this paper, we present a solution concentration model for dynamic cooling crystallization based on ultrasonic speed, using L-glutamic acid (LGA) as the case study. The speed of sound and temperature changes of the solution were recorded during the cooling crystallization process. The collected data was categorized into the undersaturated zone (USZ) and the metastable zone (MSZ) for model development. To accurately distinguish between these intervals, a noninvasive imaging device was employed to capture the exact moment of crystal formation. Our results demonstrate the feasibility of using an ultrasonic probe for in situ monitoring of concentration changes during cooling crystallization. Furthermore, an experiment involving LGA cooling crystallization was carried out to validate the model’s sensitivity in detecting the crystallization process.