Hydrodynamic electrochemistry

Figure 27.8 Tubular working electrodes for hydrodynamic electrochemistry (A) open tubular electrode (B) wire electrode in capillary (C) packed-bed tubular electrode.

Liquid chromatography (LC) and hydrodynamic electrochemistry are, for the most part, very compatible technologies which in combination yield important advantages for a number of trace determinations. In order of decreasing importance, the three major advantages are selectivity, sensitivity, and low cost. The use of modem LC for residue determinations requires a selective detector with a rapid response time, wide dynamic range, and low... 

A similar, but highly porous, vitreous carbon material—reticulated vitreous carbon (RVC)—has found widespread application for flow analysis and spectro-electrochemistry (25). As shown in Figure 4-10, RVC is an open-pore ( spongelike ) material such a network combines the electrochemical properties of glassy carbon with many structural and hydrodynamic advantages. These include a very high surface area ( 66 cm2 cm-3 for the 100-ppi grade), 90-97% void volume, and a low resistance to fluid flow. 

Data on the electrochemistry of the telluride ion in alkaline media are relatively limited. Mishra et al. [53] studied the oxidation of Te to Te° at solid electrodes, focusing on the intermediate step(s) of this process, and in particular, the possibility of detecting ditelluride Te via rotating ring disk electrode (RRDE) methodology. Oxidation beyond the elemental state to TeO and TeO was also studied using cyclic and hydrodynamic voltammetry. 

Up until the mid-1940s, most physical electrochemistry was based around the dropping mercury electrode. However, in 1942, Levich showed that rotating a disc-shaped electrode in a liquid renders it uniformly accessible to diffusion, yet the hydrodynamics of the liquid flow are soluble and the kinetic equations relatively simple. In addition, in contrast to the case of a stationary planar electrode, the current at an RDE rapidly attains a steady-state value. 

The convective diffusion theory was developed by V.G. Levich to solve specific problems in electrochemistry encountered with the rotating disc electrode. Later, he applied the classical concept of the boundary layer to a variety of practical tasks and challenges, such as particle-liquid hydrodynamics and liquid-gas interfacial problems. The conceptual transfer of the hydrodynamic boundary layer is applicable to the hydrodynamics of dissolving particles if the Peclet number (Pe) is greater than unity (Pe > 1) (9). The dimensionless Peclet number describes the relationship between convection and diffusion-driven mass transfer ... 

V. G. Levich spent a major part of his career in the world s largest institute of physical electrochemistry, The Frumkin Institute in Moscow. He was a man who had the good fortune to create a subfield in science and to dominate it during his lifetime. The field concerned is hydrodynamics applied to the relative movement of the solution near an electrode. His early work is encapsulated in a famous book Physicochemical Hydrodynamics, which was finally published in English only in 1962. The most useful equation in this book is one used in this section [Eq. (7.112)]. Later, he was persuaded by Frumkin to apply his talents to the quantum theory of charge transfer, where he led a research group of some twenty-five members. 

Introduction Some basic principles of hydrodynamics for electrochemistry... 

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