Monopolar electrode

Monopolar electrodes have a direct electrical connection with an external power supply. This requites the distribution of current over the total area of one monopolar electrode, collecting the current from the other monopolar electrode for conduction to the next cell through interceU busbars. 

Monopolar cells operate at low voltages, and may requite high amperages. Industrial citcuits of cells may consist of one hundred or more monopolar cells in series. Monopolar electrodes are used in some membrane chlor-aLkaU cells (Figs. 4 and 5), fluorine cells (Fig. 6), and in metal electrowinning cells (Fig. 7). 

Monopnictides, plutonium, 7.9 691 Monopolar electrodes, 9 621 Mono/poly soluble dyes, 7 373t Monopotassium phosphate (MKP),... 

When it is necessary to collect the gases liberated during the electrochemical process because they are either the product required or a troublesome byproduct, the vessel is closed by a suitable cover which usually is used to support the electrodes. In the case of the filter-press electrolyzers with bipolar electrodes the top of the frames usually serves as a cover. Eleotrolyzers with monopolar electrodes are closed by covers made of steel, concrete, cement, stoneware, etc. Seals between covers and vessels or electrodes are made of asbestos cord, bitumen, asphalt, mixture of kaolin and tar, cement, synthetic resins, etc. 

The middle iron plates e1, e2 etc. act as bipolar electrodes, and have on both sides extended perforated sheets n. The terminal monopolar electrodes have only one sheet n each. The diaphragm frame holds the asbestos cloth. The top edges of the electrodes and diaphragm frames have angle irons a, b, which are riveted and form a flat surface beneath the electrolyte level. This surface iB... 

The electrolytical installation consists of a series of stoneware vessels fitted with overflows the vessels are arranged in terraces so that the electrolyte flows through from one into another. The odd vessels are electrolyzers, the even ones are coolers with cooling coils of lead. Each electrolyzer is provided with a number of platinum anodes and graphite cathodes, which act as monopolar electrodes. The anodes are shaped like frames with a 0.02 mm platinum foil fixed on them. The voltage across the electrolyzer is 5.5 to 6 V usually 18 to 20 such units are... 

In a bipolar arrangement, the sacrificial electrodes are placed between the two parallel electrodes without any electrical connection. The two monopolar electrodes are connected to the electric power source with no interconnections between the sacrificial electrodes. This cell arrangement provides a simple setup, which facilitates easy maintenance. When an electric current is passed through the two electrodes, the neutral sides of the conductive plate will be transformed to charged sides, which have opposite charge compared with the parallel side beside it. The sacrificial electrodes are known as bipolar electrodes. It has been reported that EC cell with monopolar electrodes in series connection was more effective where aluminum electrodes were used as sacrificial and iron was used as anode and cathode. And, electrocoagulation with Fe/Al (anode/cathode) was more effective for the treatment process than Fe/Fe electrode pair (Modirshahla et al. 2007). 

As for the acid red 14 removal by EC, 95% color removal and 85% COD removal were obtained when the pH ranged from 6 to 9, time of electrolysis was approximately 4min and current density was approximately 80 Am-2. The results also showed that an EC cell with monopolar electrodes had higher color removal efficiency than an EC cell with bipolar electrodes. Furthermore, within an EC cell, the series connection of the monopolar electrodes was more effective for the treatment process than the parallel connection in color removal (Daneshvar et al. 2004). 

FIGURE 25.6 Needle electrodes for subcutaneous EMG recordings. For the single fiber and concentric electrodes, the cannula of the hypodermic needle acts as reference electrode. The monopolar electrode is used with a remote reference electrode. 

The stimulus may he apphed through either monopolar or bipolar electrodes. The monopolar electrode is one in which a single active electrode is placed near the excitable nerve and the return electrode is placed remotely, generally at the implantable unit itself. Bipolar electrodes are placed at the stimulation site, thus hmiting the current paths to the area between the electrodes. Generally, in monopolar stimulation the active electrode is much smaller than the return electrode, while bipolar electrodes are the same size. 

Accordingly, 99% of the total resistance is within a sphere of radius 100a, and 90% within a sphere of radius 10a. The resistance value measured with a small spherical monopolar electrode may therefore show good spatial selectivity. A concentric hemisphere is an equipotential surface, and the surface can therefore be covered by a thin metal sheet acting as one electrode. It is not a neutral electrode until r is large. As a neutral electrode, a hemispherical electrode with r oo is equal to an infinite area bottom plate at infinite distance (Figure 6.2). 

Figure 7.13 DC monopolar electrode current. Working electrode (a) platinum,...

CC monopolar electrode with high current density (e.g., for electrosurgery or nerve stimulation). 

As a part of a monopolar electrode system electrode without influence on the measurement results or on power delivery (electrosurgery). Neutral means that the current density at the electrode surface is so low that the effect of current flow is negligible. In particular used for a monopolar impedance recording CC electrode with a surface area much larger than the monopolar electrode. May also refer to an electrode situated at an inactive skin site. 

A two-electrode monopolar electrode system is used as shown in Figure 8.22. DC voltage measurement is very simple. The potential of the monopolar electrode is coupled directly... 

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