2024 AIChE Annual Meeting

(660h) Comparing Various Online and Offline Techniques to Characterize Particle Size and Shape Distributions

Authors

Jaeggi, A., ETH Zurich
Prykhodko, O., University of Manchester
Hicks, W., AstraZeneca UK
Perini, G., ETH Zurich
Mazzotti, M., ETH Zurich
Rajagopalan, A. K., The University of Manchester
The accurate characterization of the particle size and shape distribution (PSSD) of ensembles of crystals is vital for effective process design, modeling, and control. A variety of techniques to measure PSSDs have been introduced at both laboratory and pilot scales in the pharmaceutical, food, and agrochemical industries. While laser diffraction and focused beam reflectance measurement remain the industry standards, alternatives like Malvern’s Morphologi and BlazeMetrics probes are increasingly augmenting traditional methods by providing users with qualitative information about the shape of crystals through images. Nevertheless, as quantitative information these techniques provide 1D particle size distributions, thereby lumping all the shape features into a single characteristic length. This simplification, while generally adequate for quality assurance, can be deceptive during the design, modeling, or troubleshooting of processes involving crystalline products that exhibit needle- or plate-like morphologies. More advanced non-commercial imaging techniques, such as the DISCO1 (a stereoscopic imaging device), and the Petroscope2 (combined imaging- confocal microscopy), demonstrate increased capabilities in resolving the shape of crystals, particularly for needle-like and plate-like crystals. Despite the wide range of techniques available for the measurement of PSSDs, there is a noted gap in the literature concerning a comparative analysis of these methods when characterizing one, two, and three-dimensional particle size (and shape) distributions (PS(S)D) of non-equant crystals.

In this work, we systematically evaluate and compare several techniques regarding the precision with which they characterize the PSSD of particle ensembles with different sizes and shapes. We analyze the distributions obtained from six different techniques, four commercial and two non-commercial imaging tools. These devices include laser diffraction, FBRM, Mettler Toledo’s EasyViewer probe, BlazeMetrics probe, the