Physical reconstruction of packed beds and their morphological analysis: Core–shell packings as an example

• Published in: Journal of Chromatography A Vol. 1218; no. 14; pp. 1849 - 1860
• Main Authors: Bruns, Stefan, Tallarek, Ulrich
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 08.04.2011
• Subjects: Algorithms; Bed density; Capillarity; Chromatography; Chromatography, Liquid - instrumentation; Column packings; Column radial heterogeneity; Confocal laser scanning microscopy; Density; Diffusion; Dispersions; Eddy dispersion; Equipment Design; image analysis; Image Processing, Computer-Assisted; Marine; Microscopy, Confocal; microstructure; Models, Statistical; Morphology–transport relationships; Packed beds; Particle Size; Porosity; Reconstruction; Reconstruction of packed beds; statistical analysis; Reconstruction of packed beds; Column radial heterogeneity; Eddy dispersion; Bed density; Morphology–transport relationships; Confocal laser scanning microscopy
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2011.02.013

We report a fast, nondestructive, and quantitative approach to characterize the morphology of packed beds of fine particles by their three-dimensional reconstruction from confocal laser scanning microscopy images, exemplarily shown for a 100 μm i.d. fused-silica capillary packed with 2.6 μm-sized core–shell particles. The presented method is generally applicable to silica-based capillary columns, monolithic or particulate, and comprises column pretreatment, image acquisition, image processing, and statistical analysis of the image data. It defines a unique platform for fundamental comparisons of particulate and monolithic supports using the statistical measures derived from their reconstructions. Received morphological data are column cross-sectional porosity profiles and chord length distributions from the interparticle macropore space, which are a descriptor of local density and can be characterized by a simplified k-gamma distribution. This distribution function provides a parameter of location and a parameter of dispersion which can be correlated to individual chromatographic band broadening processes (i.e., to transchannel and short-range interchannel contributions to eddy dispersion, respectively). Together with the transcolumn porosity profile the presented approach allows to analyze and quantify the packing microstructure from pore to column scale and therefore holds great promise in a comparative study of packing conditions and particle properties, particularly for characterizing and minimizing the packing process-specific heterogeneities in the final bed structure.