Influence of the pillar shape on the band broadening and the separation impedance of perfectly ordered 2-D porous chromatographic media

We report on a computational study assessing the effect of the pillar shape in perfectly ordered porous chromatographic media. Using computational fluid dynamics to compare the band broadening and flow resistance characteristics of a large number of different pillar shapes, it is found that the most axially elongated shapes yield the best chromatographic performance and that diamonds are to be preferred over ellipsoids. The former pack into a more uniform pore space and display a smaller C. value, whereas the latter pack into a locally constricted pore space and therefore generate a considerably larger flow resistance. For the presently considered case of a densely packed array (epsilon = 0.4), changing the pillar shape from a cylinder to a more elongated diamond, for example, reduces the minimal plate heights from h(min) = 0.84 to h(min) = 0.72, the C factor from C = 0.062 to C = 0.050, and the separation impedance from E-min = 330 to E-min = 220, without affecting the number of interchannel coupling points.