Other Cell Designs

An alternative to using a rectangular plate as an electrode is to use a disk as in the BASF capillary gap cell, later called a disk-stack cell (Fig. 5.8a). It is a stack of horizontally mounted plates in a cylindrical outer shell. Thin 

FIGURE 5.8. Narrow gap cells, (a) BASF capillary gap cell (b) pump cell. 

Instead of pumping the electrolyte through the cell by means of an external pump, the cell itself can be made to perform this function by rotating the disk on a central spindle as in the pump cell (Fig. 5.8b). Higher mass transfer rates and current densities can be achieved than in the disk-stack cell but have to be paid for in higher capital and maintenance costs, which limit the application of rotating devices in industry. 

Rotation has also been applied to electrodes of cylindrical geometry (Fig. 5.9) where typically the electrode is rotated axially in a concentric cylinder unit. This has been applied to small-scale electroorganic synthesis and to metal recovery from eflBuents where the rotation assists in recovering the metal in powder form. 

In an attempt to increase the specific electrode area of the reactor, electrodes, spacers, and separators are wound in a spiral form (Fig. 5.10) in the Swiss Roll cell. Electrolyte flows axially in the narrow channels between electrodes and separator. In this compact design, the main problem is the need for flexible foil electrodes, spacers, and separators and the cost and difficulty of replacing damaged components. Nevertheless, the design has been used for relatively small-scale organic applications.  

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Other Cell Designs. Although not used in the United States, another important cell is based on designs developed by ICl (90). Cells of this type are used by British Nuclear Fuels pic and differ from the cells shown in Figures 2 and 3 in two ways (/) the anodes used are made of the same hard, nongraphitized carbon, but are more porous and 2) the cathodes are formed from coiled tubes and provide additional cooling (91). 

Other cell designs, flow cells, can be found in literature [47]. In this design, a flow sonoelectrochemical reactor is the operational unit in a batch recirculation system, see Fig. 4.4. In this, analyzing the performance of the sonoelectrochemical degradation of trichloroacetic acid, influence of the fluid flow, gases evacuation system and, especially, the maintenance of the values of the performance parameters in the scale-up were checked. 

EPR spectrochemical experiments yield information about (i) the site of redox activity in the compound (ii) the contribution of various nuclei to the molecular orbital occupied by the unpaired electron that may then be checked against the results of theoretical calculations and (iii) the half-wave potentials of systems where direct measurement is difficult (usually as a result of slow electron-transfer rates). Examples of each of these have been taken from our investigations and are detailed below. Initially, however, the cell used in these experiments is described followed by a review of some other cell designs. 

Some authors have used conventional glass cell in sealed autoclave, but in this case the temperature was limited to 225 °C (Campbell et al, 1954), 230 °C (Korobkov et al., 1970), 250 °C (Baghalha and Papangelakis, 2000), 300 °C (Gorbachev and Kondrat ev, 1961, 1965 Kondrat ev and Nikich, 1963, Polyakov, 1965) or 340 °C (Rodnanskii and Galinker, 1955) and saturation vapor pressure. Other cell designs (Bannard, 1975 Goemans et al., 1997) used a furnace to heat the middle part of the cell while the end parts, where the pressure seals are located, remains cold. 

Metal support cells are proposed to realize cost reduction from the materials cost and fabrication cost simultaneously. Compared with nickel which is the major component in the anode support cells, the metal support cells aim at using cheaper Fe-Cr alloy as supporting materials [19]. Instead, the fabrication process becomes rather difficult compared with other cell design. 

S. Other cell-design features, including the form of the electrodes and the presence or absence of a separator or a membrane. 

Other cell designs, such as radial configurations and more recently microtubular designs, have also been developed and demonstrated [21]. The microtubular designs can achieve lower operating temperature, since it has long been recognized that thinner electrolyte and electrode layers promote operation at lower temperature [22]. 

Ethylene glycol can be produced by an electrohydrodimerization of formaldehyde (16). The process has a number of variables necessary for optimum current efficiency including pH, electrolyte, temperature, methanol concentration, electrode materials, and cell design. Other methods include production of valuable oxidized materials at the electrochemical cell s anode simultaneous with formation of glycol at the cathode (17). The compound formed at the anode maybe used for commercial value direcdy, or coupled as an oxidant in a separate process. 

Other commercial cells designed for the electrolysis of fused sodium chloride iaclude the Danneel-Lon2a cell and the Seward cell, both used before World War I. The former had no diaphragm and the sodium was confined to the cathode 2one by salt curtains (ceramic walls) the latter utili2ed the contact-electrode principle, where the cathode was immersed only a few millimeters ia the electrolyte. The Ciba cell was used over a longer period of time. 

Separator s a physical barrier between the positive and negative electrodes incorporated into most cell designs to prevent electrical shorting. The separator can be a gelled electrolyte or a microporous plastic film or other porous inert material filled with electrolyte. Separators must be permeable to ions and inert in the battery environment. 

The other example, called the nickel/ zinc battery [(-Zn)/KOH/NiOOH(+)], has attracted more attention in two different versions from the "application" and "cell design" viewpoints one is the small cylindrical consumer cell [30], the other one is the flat-plate module for electrotraction [31], A very interesting review with an extended collection of references was pub-... 

The influenza virus inhibitors, zanamivir, and oseltamivir, act outside the cell after virus particles have been formed. The dtugs have been designed to fit into the active site of the viral envelope enzyme neuraminidase, which is required to cleave sialic acid off the surface of the producing cells. When its activity is blocked, new virus particles stay attached to the cell surface through binding of the virus protein hemagglutinin to sialic acid and are prevented from spreading to other cells. 

The other important factor in cell design optimization is the specific energy consumption, es, defined as ... 

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