Parallel-plate cell

Mass Transport. Probably the most iavestigated physical phenomenon ia an electrode process is mass transfer ia the form of a limiting current. A limiting current density is that which is controlled by reactant supply to the electrode surface and not the appHed electrode potential (42). For a simple analysis usiag the limiting current characteristics of various correlations for flow conditions ia a parallel plate cell, see Reference 43. 

Eig. 5. Options for electrolyte flow through parallel plate cells (a), parallel, and (b), series flow. 

Two-Dimensional Electrode Flow Cells. The simplest and least expensive cell design is the undivided parallel plate cell with electrolyte flow by some form of manifold. Electrical power is monopolar to the cell pack (72). An exploded view of the Foreman and Veatch cell is shown in Figure 7. Note that electrolyte flow is in series and that it is not easily adapted for divided cell operation. 

Because of its advantages (high sensitivity and selectivity, low cost and miniaturization) amperometric detection has been frequently used in flow injection analysis (FIA) and RP-HPLC. However, it has been established that the peak area (detector response) considerably depends on the flow rate. A general approach has been proposed to predict the effect of flow rate on the peak area in FIA and RP-HPLC. The general form of the correlation describing the flow in a parallel plate cell with short rectangular electrodes is... 

For a couette flow, the light transmission axis is often directed along the vorticity axis so that G = 0 and < > = n/2. In this case, An = An12 and a = %. Another frequently used geometry is the parallel plate cell, where the light propagates along... 

Several investigations [56,57] have been devoted to the electrochemical treatment of human wastes in an attempt to make possible its electrochemical combustion. Tennakoon et al. [57] degraded artificial feces/urine mixtures at 90°C in a U tube cell, further scaling up the process to a parallel plate cell... 

The nitrate would be electrolyzed in a 24-hr cycle in parallel-plate cells with proton-exchange membranes. The optimal overall NO reduction reactions are... 

The current distribution has to be completely uniform. A parallel plate cell configuration is important. Edge effects should be eliminated. 

Figure 10.8. Parallel plate cell the aluminium plates function both as the waveguide walls and as the Stark plates [2].

Fig. 7.2 Discontinuous cells used in the experiments - cell with rotating anode (left) and flowthrough cell with parallel plate electrodes (right). (1) Rotating contact, (2) electronically controlled stirrer, (3) thermostated beaker, (4) plate cathode with central hole or expanded mesh cathode, (5) rotating disk or expanded mesh anode, (6) parallel plate cell, (7) centrifugal pump, (8) stirred dark container for sampling, (9) magnetic stirrer, (10) cryostat...

Fig. 7.6 Active chlorine formation in parallel plate cell at very low chloride concentrations as indicated in the legend (IrCE/RuCE electrodes, 150Am 2, 750mL, 20°C, 0.8 and 1.4ppm chloride + 232 ppm sulphate + 5 ppm carbonate as sodium salts)...

Fig. 7.13 Perchlorate formation in the discontinuous parallel plate cell using BDD electrodes and artificial waters (200 Am-2, 650mL, 20°C)...

Fig. 7.22 Analysis values of active chlorine in discontinuous experiments using discontinuous parallel plate cell with MIO electrodes. Samples were analysed by DPD and in parallel by UV spectrophotometry after shifting pH to high values by adding 25 pi 2 M NaOH to the 50-mm cuvette (150mA, 240ppm sulphate + 25 ppm chloride as sodium salts, 20°C)...

The various configurations for a reference electrode in such a parallel plate cell have been analyzed a convenient way is to place the reference electrode in the feed line and compensate for ohmic potential drop [55]. 

Laboratory and industrial parallel plate cells (filterpress cells) are commercially available from ICI [60], Electrocell AB/Electrosynthesis [61], Reilly Tar and Chemical [62], and Electricity Company [63]. 

In the case of the thermal-conductivity, there are three main techniques those based on Equation (1) and those based on a transient application of it. Prior to about 1975, two forms of steady-state technique dominated the field parallel-plate devices, in which the temperature difference between two parallel disks either side of a fluid is measured when heat is generated in one plate, and concentric cylinder devices that apply the same technique in an obviously different geometry. In both cases, early work ignored the effects of convection. In more recent work, exemplified by the careful work in Amsterdam with parallel plates, and in Paris with concentric cylinders, the effects of convection have been investigated. Indeed, the parallel-plate cells employed in Amsterdam by van den Berg and his co-workers have the unique feature that, because the temperature difference imposed can be very small and the horizontal fluid layer very thin, it is possible to approach the critical point in a fluid or fluid mixture very closely (mK). 

In the traditional cells, the cathodes and anodes are flat plates that are placed parallel to each other. Anodes and cathodes are suspended alternately in the cells with precise spacing. In some cases, it is necessary to separate anode and cathode electrolytes. This is done by using separators, with diaphragms that allow solution flow or membranes that allow only anion or cation transfer. The deposition of metal onto the cathodes is a batch process. The cathodes are removed from the cell when the deposit has grown thick enough. The flow rate of the electrolyte is kept low so that possible solids fall to the bottom of the cell and do not contaminate the cathodes. Figure 10 shows an example of the traditional parallel-plate cell. 

Fig. 10 Parallel-plate cell used in traditional electrowinning and electrorefining.

In the traditional parallel-plate cells, the Walker system is the most commonly used electrical arrangement (Fig. 13). In this system, the current flows from a copper busbar on one side of the cell to the anodes, and the cathodes are connected to another busbar on the opposing side of the cell. The second busbar feeds current to the anodes of the second cell, and so on. In the Walker system, only one side of each electrode is connected to the electric circuit. The intercell busbars do not require so much thickness as the end busbars as the current flows through the path of least resistance. 

Fig.6. Configuration of a vertical parallel-plate cell [10]. a Side view b Cross section view (X-X ) (1) silicone tube (outer diameter, 4 mm), (2) glass plate (length x width x thickness, 50x50x3 mm), (3) copper wire (diameter, 1 mm), (4) electrode (gold-plated copper foil diameter, 20 mm thickness, 0.035 mm), (5) guard electrode (gold-plated copper foil diameter, 22 mm thickness, 0.035 mm), (6) electrode (gold-plated copper foil length x width x thickness, 50x50x0.035 mm), (7) epoxy adhesives, (8) epoxy resin (thickness, 1.5-2.5 mm)...

A. Parallel plate cell a. Vertical type Aluminum Circle 2b No 71... 

Previous SDE development by Westinghouse Electric [10] utilised a two-compartment, flowthrough parallel plate cell with a porous rubber diaphragm separating the reaction compartments. Tire half-cell reactions are as follows ... 

The metals present can be recovered in a batch process using packed-bed deposition, dissolution, and potentiostatic deposition of individual ions described earlier (cf. [30]). The nitrates can be electrolyzed in a 24 h cycle in parallel plate cells with proton exchange membranes. Thus,... 

When a very thin slab ( 0.1 mmx 7 mm) of photons with a flux of 10 to 10 photons/sec is allowed to incident upon a parallel plate cell (Fig. 7 b), f 1 can be achieved and Eq (16) becomes... 

For the determination of ICE using the COD method and to study the influence of hydrodynamic conditions on ICE a parallel plate cell with external circulation of the electrolyte was used. 

The parallel plate cell is constructed in two halves each with two electrodes Anode-Cathode (100 cm2 surface each) inlaid in polypropylene blocks. On one of the halves inlet and outlets were provided for circulation of the electrol3d . The interelectrode gap was 4 mm (thickness of the viton gasket). 

Circulation of the electrolyte through the parallel plate cell was provided by a magnetic pump (Iwaki MD 50 R) and the electrolyte flow rate was measured with a magneto hydrodynamic flow meter (Deltaflux). 

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