Comparison of first and second generation analytical silica monoliths by pore-scale simulations of eddy dispersion in the bulk region.
Comparison of first and second generation analytical silica monoliths by pore-scale simulations of eddy dispersion in the bulk region.
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DOI：
10.1016/j.chroma.2013.06.039
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发表时间：
2013-08
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影响因子：
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通讯作者：
D. Hlushkou;Kristof Hormann;A. Höltzel;S. Khirevich;A. Seidel-Morgenstern;U. Tallarek
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文献类型：
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作者：
D. Hlushkou;Kristof Hormann;A. Höltzel;S. Khirevich;A. Seidel-Morgenstern;U. Tallarek
我们提出了第一个定量比较涡流分散在大孔（流过）空间的第一代和第二代分析硅胶整体。基于从Chromolith柱体区采集的样品，采用共聚焦激光扫描显微镜对大块大孔空间进行了物理重构，作为孔隙尺度流动和分散模拟的模型。我们的研究结果涵盖了三维速度场、宏观达西渗透率、瞬态和渐近色散行为以及色谱带展宽的细节，从而将形态、微观和宏观性质联系起来。通过对模拟板高数据的Giddings分析，获得了整体中单个涡流弥散贡献的完整参数集。确定的短程结构非均质性对应于各自单体的平均畴尺寸。我们的板高曲线显示，第二代单体体形态的结构改进对观察到的整体柱效率的改善只起了很小的作用。结果还表明，第一代和第二代分析硅胶整体之间存在拓扑差异，这就提出了如何在不影响床层结构均匀性的情况下进一步减小硅胶整体的畴尺寸的问题。
We present the first quantitative comparison of eddy dispersion in the bulk macropore (flow-through) space of 1st and 2nd generation analytical silica monoliths. Based on samples taken from the bulk region of Chromolith columns, segments of the bulk macropore space were physically reconstructed by confocal laser scanning microscopy to serve as models in pore-scale simulations of flow and dispersion. Our results cover details of the 3D velocity field, macroscopic Darcy permeability, transient and asymptotic dispersion behavior, and chromatographic band broadening, and thus correlate morphological, microscopic, and macroscopic properties. A complete set of parameters for the individual eddy dispersion contributions in the bulk was obtained from a Giddings analysis of the simulated plate height data. The identified short-range structural heterogeneities correspond to the average domain size of the respective monoliths. Our plate height curves show that structural improvements in the bulk morphology of 2nd generation monoliths play only a minor role for the observed improvement in overall column efficiency. The results also indicate a topological dissimilarity between 1st and 2nd generation analytical silica monoliths, which raises the question how the domain size of silica monoliths can be further decreased without compromising the structural homogeneity of the bed.