Axial dispersion in single pellet-string columns packed with unusually shaped porous pellets

Axial dispersion in the single pellet-string arrangement of a chromatographic column (SPSC) packed with 15 types of pellets with various shapes was studied. Non-porous cylindrical pellets and non-spherical porous pellets with pores blocked by a liquid (Porofil) were used. For different tracer- and carrier-gases (carrier-gases: N2, H2; tracer-gases: H2, He, N2, Ar) comparable dependencies of Bodenstein numbers, Bo, versus the product of Reynolds and Schmidt numbers, Re Sc, were obtained. Tracer dispersion due to extra-column effects was eliminated via convolution of column responses for two column lengths. Reproducibility of axial dispersion determination was verified by repeated column repacking. An interpolation equation for different pellet shapes was proposed. The pellet shape is characterized through pellet sphericity, φ, and the pellet/column diameter ratio, dp/dc. The effectiveness of axial dispersion correlations was confirmed for sphericity 0.427-0.89 and the pellet/column diameter ratios 0.35-0.87.