期刊
JOURNAL OF CHROMATOGRAPHY A
卷 1407, 期 -, 页码 139-156出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.chroma.2015.06.047
关键词
Band broadening; Plate height contributions; Core-shell particles; Lattice-Boltzmann method; Random walk; Discontinuous diffusion coefficient
资金
- Deutsche Forschungsgemeinschaft DFG (Bonn, Germany) [TA 268/5-1]
- John von Neumann Institute for Computing (NIC) [8214]
- Julich Supercomputing Center (JSC) [HMR10]
In recent years, chromatographic columns packed with core-shell particles have been widely used for efficient and fast separations at comparatively low operating pressure. However, the influence of the porous shell properties on the mass transfer kinetics in core-shell packings is still not fully understood. We report on results obtained with a modeling approach to simulate three-dimensional advective-diffusive transport in bulk random packings of monosized core-shell particles, covering a range of reduced mobile phase flow velocities from 0.5 up to 1000. The impact of the effective diffusivity of analyte molecules in the porous shell and the shell thickness on the resulting plate height was investigated. An extension of Giddings' theory of coupled eddy dispersion to account for retention of analyte molecules due to stagnant regions in porous shells with zero mobile phase flow velocity is presented. The plate height equation involving a modified eddy dispersion term excellently describes simulated data obtained for particle-packings with varied shell thickness and shell diffusion coefficient. It is confirmed that the model of trans-particle mass transfer resistance of core-shell particles by Kaczmarski and Guiochon [42] is applicable up to a constant factor. We analyze individual contributions to the plate height from different mass transfer mechanisms in dependence of the shell parameters. The simulations demonstrate that a reduction of plate height in packings of core-shell relative to fully porous particles arises mainly due to reduced trans-particle mass transfer resistance and transchannel eddy dispersion. (C) 2015 Elsevier B.V. All rights reserved.
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