Vrije Universiteit Brussel, Brussels, Belgium.
J Chromatogr A. 2011 Sep 23;1218(38):6654-62. doi: 10.1016/j.chroma.2011.07.055. Epub 2011 Jul 24.
The effect of the addition of 25%, 50% and 75% (weight percent, wt%) of larger particles (resp. 3 and 5 μm) to a commercial batch of 1.9 μm particles has been investigated as an academic exercise to study the effects of particle size distribution on the kinetic performance of packed bed columns in a magnified way. Comparing the performance of the different mixtures in a kinetic plot, it could be irrefutably shown that the addition of larger particles to a commercial batch of small particles cannot be expected to lead to an improved kinetic performance. Whereas the addition of 25 wt% of larger particles still only has a minor negative effect, a significantly deteriorated performance is obtained when 50 or 75 wt% of larger particles are added. In this case, separation impedance number increases up to 200% were observed. Studying the packing structure through computational packing simulations, together with the experimental determination of the external porosity, helped in understanding the obtained results. This showed that small particles tend to settle in the flow-through pores surrounding the larger particles, leading to very high packing densities (external porosities as low as 32% were observed) and also negatively influencing the column permeability as well as the band broadening (because of the broadened flow-through pore size range).
将 25%、50%和 75%（重量百分比，wt%）的较大颗粒（分别为 3μm 和 5μm）添加到商业批次的 1.9μm 颗粒中，作为一项学术研究，以放大方式研究粒径分布对填充床柱动力学性能的影响。通过在动力学图中比较不同混合物的性能，可以无可置疑地表明，将较大颗粒添加到商业批次的小颗粒中，不能期望改善动力学性能。虽然添加 25wt%的较大颗粒仍只有较小的负面影响，但当添加 50wt%或 75wt%的较大颗粒时，性能会显著恶化。在这种情况下，观察到分离阻抗数增加了高达 200%。通过计算填充模拟和外部孔隙率的实验测定来研究填充结构，有助于理解所得到的结果。这表明，小颗粒往往会在较大颗粒周围的贯穿流孔中沉降，导致非常高的填充密度（观察到的外部孔隙率低至 32%），并对柱渗透性和带宽展宽（由于贯穿流孔尺寸范围变宽）产生负面影响。
