Effect of Air Injection on Nucleation Rates: An Approach from Induction Time Statistics

• Published in: Crystal growth & design Vol. 17; no. 6; pp. 3287 - 3294
• Main Authors: Capellades, Gerard, Kiil, Søren, Dam-Johansen, Kim, Mealy, Michael J., Christensen, Troels V., Myerson, Allan S.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 07.06.2017
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.7b00267

From disruption of the supersaturated solution to improved mass transfer in the crystallizing suspension, the introduction of a moving gas phase in a crystallizer could lead to improved rates of nucleation and crystal growth. In this work, saturated air has been injected to batch crystallizers to study the effects on formation of the first crystal and subsequent turbidity buildup. To account for the typically large sample-to-sample variation, nucleation rates were evaluated for a large number of replicates using probability distributions of induction times. The slope and the intercept of the distributions were studied independently, allowing the simultaneous determination of the mean induction time and a certain detection delay related to the rate of crystal growth after formation of the first nucleus. When saturated air was injected in aqueous glycine solutions, the average detection delay was reduced from 69 to 13 min, and the mean induction time decreased from 128 to 36 min. The effect on aqueous solutions of l-arginine was less apparent, with a detection delay reduction from 15 to 3 min, and no significant changes on the rate of primary nucleation. These results demonstrate the potential of this technique for reduction in nucleation induction time and improved mass deposition rates in crystallization operations.