G. Weyns

Ion Transport Models for Electroanalytical Simulation. 1. Theoretical Comparison

Ion transport models are compared by computing the limiting current density of an electrodeposition on a rotating disk electrode for various hypothetical electrolytes. The first ion transport model is the pseudoideal solution model, on which many commercial electroanalytical simulation tools are built. The second, more rigorous model consists of the linear phenomenological equations for which the activity coefficients and Onsager coefficients are calculated locally with the mean spherical approximation (MSA).

Study of Ion Transport Models for Electroanalytical Simulation. Part 2: Experimental Comparison †

Ion transport models are compared by simulating the limiting current density of copper deposition from aqueous CuSO(4) solutions on a rotating disk electrode. The first ion transport model is the pseudoideal solution model, on which many commercial electroanalytical simulation tools are built. The second, more rigorous model consists of the linear phenomenological equations for which the activity coefficients and Onsager coefficients are calculated locally with the mean spherical approximation (MSA). The influence of the formal association constant in the pseudoideal solution model is also investigated.

INFLUENCE OF THE PILLAR SHAPE ON THE BAND BROADENING IN PRESSURE-DRIVEN AND ELECTRO-OSMOSIS-DRIVEN ORDERED 2D POROUS CHROMATOGRAPHIC COLUMNS

A newly developed computational fluid dynamics method for simulating chromatographic adsorption is presented. This well-validated software package takes adsorption reactions as well as internal porosity into account to explain differences caused by the design and flow regime. Focusing on the band broadening in perfectly ordered 2D chromatographic columns, it is found that the method used for forcing the fluid through the column has a significant influence. Electro-osmosis-driven (ED) flows have a slight advantage (i.e. produce less band broadening) over pressure-driven (PD) flows. This is explained by the way the flow passes through a tortuous pore structure with changing pore size. Furthermore, this behavior does not change when the shape of the pillars is changed. Only for hexagon-like shapes is there a slight gain in performance for ED flows based on a bigger recuperation mechanism typical of ED flows in undulating pore spaces. When concentrating on the effect of the pillar, a better performance is obtained for more elongated shapes compared to more compact shapes like cylinders, as they pack in a more uniform pore space. It is also observed that the uniformity of the fluid field is the most important factor when comparing different shapes or systems. Heterogeneity in the velocity field inevitably leads to an increase of the band broadening.