Electrochemical processes, overview

In this chapter, we describe some of the more widely used and successful kinetic techniques involving controlled hydrodynamics. We briefly discuss the nature of mass transport associated with each method, and assess the attributes and drawbacks. While the application of hydrodynamic methods to liquid liquid interfaces has largely involved the study of spontaneous processes, several of these methods can be used to investigate electrochemical processes at polarized ITIES we consider these applications when appropriate. We aim to provide an historical overview of the field, but since some of the older techniques have been reviewed extensively [2,3,13], we emphasize the most recent developments and applications. 

In addition to the function as reaction medium - as in all chemical reactions - in electrochemical processes, the electrolyte has to provide the transport of ions between the electrodes. An optimal combination of solvent and supporting electrolyte has to be found, considering the reaction conditions and the properties of reactants, products, and electrodes. A short overview of usual electrolytes - and some examples of unconventional electrolytes as thought-provoking impulse for research - is given... 

The most common applications of electrochemical processes of lead are lead-acid batteries, described in detail elsewhere ([1, 203, 346-349] and references given therein). Some detailed aspects of the electrochemistry of lead-acid batteries have already been described in the Sects 24.3.2.4 and 24.3.2.5. Therefore, only an overview of the main properties of this kind of power sources will be presented. 

In the remaining sections of this chapter, overviews of various electrochemical processes/sys-tems are presented. Where appropriate, these overviews refer back to the fundamental principles and theories presented above. 

General methods for the synthesis of biaryls will be reviewed in this section. Electrochemical processes are outside the scope of this work. Asymmetric syntheses have been excellently reviewed recently by Bringmann [9] and therefore will not be overviewed here. 

Fig. 31.4 Schematic illustration of the electrochemical processes that lead to cathodic delamination of polymer films from iron substrates (current /, galvanic potential difference A ). Middle overview of the polarization curves at the defect (left), the intact interface (right). Bottom the situation after galvanic coupling of these two parts.

In the limit of fast, reversible redox processes (i.e., thermodynamic equilibrium is maintained throughout the electrochemical process), the pH-dependence is given by the Nernst equation. The basic theory has received thorough treatment, and only a brief overview is given here. 

Batteries for storage of electricity from solar and wind generation farms are a key element in the success of sustainability. Electric vehicles are the second link in the chain powered by advanced battery systems. This section describes the various devices used in electrochemical energy storage including an overview of electrochemical processes and devices. 

In the first section, some fundamentals of electrochemical processes are defined. Common industrially relevant process flow schemes and equipment are described in the second section. The third section discusses the interest of microstructured reactors in electrochemical synthesis and gives an overview of the recent literature in this area. 

In closing this overview, it is important to emphasize that the three fields mentioned above need not be the only fields. As CRE encompasses more and more chemistry-based disciplines into its fold, the nnmber of field equations is likely to increase. For instance, when reaction engineers looked at electrochemical processes, they found the need to inclnde a set of equations defining the electrochemical field in the analysis and design of electrochemical reactors. Similarly, when sonochanical reactions were added, a new set of equations defining the sonochemical field had to be added, and so on. 

The aim of this overview is first to present the general principles of electrocatalysis by metal complexes, followed by a series of selected examples published over the last 20 years illustrating the major electrochemical reactions catalyzed by metal complexes and their potential applications in synthetic and biomimetic processes, and also in the development of sensory devices. The area of metal complex catalysts in electrochemical reactions was reviewed in 1990.1... 

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