Electrochemical methods reactor

Figure 4.30 Electrochemical micro reactor, a diaphragm micro flow cell, applied to perform the cation flow method. Assembled device (left). Disassembled device showing the two compartments of the cell within the housings and the diaphragm (right) [67. ...

In the cation flow method an organic cation is generated continuously by low temperature electrolysis using an electrochemical microflow reactor. The cation thus generated is immediately allowed to react with a carbon nucleophile in the flow system. This method, in principle, enables the manipulation of highly reactive organic cations. 

When one is dealing with localized corrosion processes, the tendency is experimentally to determine or model whether a particular process can occur in a specific environment i.e., to determine the susceptibility. Such procedures are invaluable in materials selection, and the use of electrochemical methods is an integral part of these efforts. However, in some environments it is injudicious to assume that localized corrosion will not occur. One example would be SCC in nuclear reactor heat exchangers and other components. In other applications, the need to minimize materials costs leads to the selection of materials for which there is no guarantee of immunity to localized corrosion. For such applications there is a strong need for models that will predict how fast such processes will propagate once they are initiated and what kind and extent of damage will accumulate. 

Figure 5.8 Electrochemical microflow reactor for the cation-flow method (a) outside (b) inside (anodic part). Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with permission...

The determination of the real surface area of the electrocatalysts is an important factor for the calculation of the important parameters in the electrochemical reactors. It has been noticed that the real surface area determined by the electrochemical methods depends on the method used and on the experimental conditions. The STM and similar techniques are quite expensive for this single purpose. It is possible to determine the real surface area by means of different electrochemical methods in the aqueous and non-aqueous solutions in the presence of a non-adsorbing electrolyte. The values of the roughness factor using the methods based on the Gouy-Chapman theory are dependent on the diffuse layer thickness via the electrolyte concentration or the solvent dielectric constant. In general, the methods for the determination of the real area are based on either the mass transfer processes under diffusion control, or the adsorption processes at the surface or the measurements of the differential capacitance in the double layer region [56],... 

Figure 12.9 An electrochemical microflow reactor for the cation flow method.

The electrochemical method for the treatment of wastewater containing organic pollutants has attracted a great deal of attention recently (1). Mainly because of the ease of control and the increased efficiencies provided by the use of new electrode material (2,3,4,5) and compact bipolar electrochemical reactor (6). 

EnFACE is an electrochemical method that consists of specialized electrochemical reactor for transfer of micropattem on metal substrates. EnFACE is an acronym for Electrochemical Nano and micro-Fabrication by optimizing Chemistry and Engineering. This is a disruptive electrochemical deposition and dissolution process with the potential to create alternative to many existing micropatteming techniques. 

Post-chromatographic photochemical derivatization Solid-phase reactors Electrochemical methods... 

The generation of the cation can be monitored using an FTIR spectrometer (ATR method) equipped with a low-temperature flow cell attached to the outlet of the electrochemical microflow reactor. The absorption at 1814 cm , which is assigned as the C=0 vibration, increases with increase in the electric current. An interesting application of the cation flow method is continuous sequential combinatorial... 

Some part of the spent fuel of atomic reactors is reprocessed separating uranium, plutonium, and the fission products, in order to produce new fissionable fuel or to collect some part of the valuable fission products. While several reprocessing methods have been proposed, the Purex process is the most widely used all over the world. The process uses 30% tributyl phosphate, TBP, as extractant in dodecane or kerosene solvent that is used to decrease the viscosity and the density of the liquid. The mixture is easily separated from water. The spent fuel is dissolved in concentrated nitric acid and the aqueous solution is mixed with the organic extractant. U and Pu present in the aqueous phase in the forms U02 and Pu are extracted to the organic phase, the fission products remain in the aqueous solution. After reduction of Pu by chemical or electrochemical method, Pu goes back to the aqueous phase, while the uranium remains in the organic phase (Benndict et al., 1981 Choppin et al. 1995 Katsumura 2004). 

A significant amount of research has been performed on the measurement of liquid-solid mass transfer [67], Generally, liquid-solid mass transfer in fixed-bed reactors has been studied by five methods dissolution of slightly soluble solids into the liquid [68-73], chemical reaction with significant liquid-solid mass transfer resistance [74], ion exchange followed by an instantaneous irreversible reaction [75], dynamic absorption [76], and electrochemical technique [77-80]. The electrochemical method has certain advantages over the other it facilitates direct and instantaneous measurements of solid-liquid mass transfer and is thus very useful to measure mass transfer fluctuations, especially under pulse flow conditions. 

Complete mineralization of a pollutant can be achievable by combining biological and electrochemical methods. For example, tetracycline can be completely biologically mineralized after a single pass through commercially available graphite felt into a percolated electrochemical reactor (Fig. 7) [22]. 

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