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Study of mass transport in electro fluid dynamic devices Wang, Su

Abstract

Mass transport in one dimensional (1D) and two-dimensional (2D) electro-fluid dynamic devices for chemical separation is systematically studied. For 1D EFD devices, like capillary electrophoresis (CE), adding external pressure during the process usually results in unwanted band broadening. However, frontal analysis (FA) can potentially benefit from the external pressure by significantly reducing the amount of time needed for analysis. Therefore, the possible impact of the pressure-assisted capillary electrophoresis frontal analysis (PACE-FA) is studied. With a typical CE-FA set-up and a typically used length and internal diameter of the capillary used, it was found that the detected concentrations of analyte will not be significantly affected by an external pressure less than 5 psi in the simulation model. In addition, the measured ligand concentration in PACE-FA was also not affected by common variables such as molecular diffusion coefficient and capillary length within the tested range. By using PACE-FA to study the binding interactions between hydroxypropyl β-cyclodextrin (HP-β-CD) and small ligand molecules, the binding constants determined by CE-FA (18.3±0.8 M-1) and PACE-FA (16.5±0.5 M-1) are found to be similar. Based on the experimental results, it is concluded that PACE-FA can reduce the time of binding analysis while maintaining the accuracy of the measurements. For 2D-EFD device, an EFD desalination chip was designed; the desalting process was then modeled (both in single-element and multiple-element geometric design) and was simulated. The simulation results showed that the ionic components were separated and outflowed to specific channels as designed which suggests a potential alternative way for microscale-desalination. The result of this study also showed that the performance of the device relied on the geometry of the device relatively heavily and can be improved by applying a stronger electric field at the electrodes.

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Attribution-NonCommercial-NoDerivatives 4.0 International