Bipolar electrode

The lshi2uka cell (39—41), another multipolar cell that has been ia use by Showa Titanium (Toyama, Japan), is a cylindrical cell divided ia half by a refractory wall. Each half is further divided iato an electrolysis chamber and a metal collection chamber. The electrolysis chamber contains terminal and center cathodes, with an anode placed between each cathode pair. Several bipolar electrodes are placed between each anode—cathode pair. The cell operates at 670°C and a current of 50 kA, which is equivalent to a 300 kA monopolar cell. 

In 1976 the first section of a new smelting process that requited 30% less electric power than the best Hah-HAroult cehs came on stream. In this process, alumina, carbon, and chlorine reacted to produce aluminum chloride and carbon dioxide. The aluminum chloride was electrolyzed in bipolar electrode cehs to produce aluminum and chlorine and the chlorine was recycled to make more aluminum chloride. After six years of operation, the plant... 

Research and development efforts have been directed toward improved ceU designs, theoretical electrochemical studies of magnesium ceUs, and improved cathode conditions. A stacked-type bipolar electrode ceU has been operated on a lab scale (112). Electrochemical studies of the mechanism of magnesium ion reduction have determined that it is a two-electron reversible process that is mass-transfer controUed (113). A review of magnesium production is found ia Reference 114. 

A possible problem of sealing the electrolyte path is found in the Foreman and Veatch cell. This can be avoided by placing the cells in a vessel. The best known example of this is the Beck and Guthke cell shown in Figure 8 (74). The cell consists of a stack of circular bipolar electrodes in which the electrolyte is fed to the center and flows radially out. Synthesis experience using this cell at BASF has been described (76). This cell exhibits problems of current by-pass at the inner and outer edge of the disk cells. Where this has become a serious problem, insulator edges have been fitted. The cell stack has parallel electrolyte flow however, it is not readily adaptable to divided cell operation. 

As in aqueous electrochemistry it appears that application of a potential between the two terminal (Au) electrodes leads to charge separation on the Pt film so that half of it is charged positively and half negatively8 thus establishing two individual galvanic cells. The Pt film becomes a bipolar electrode and half of it is polarized anodically while the other half is polarized cathodically. The fact that p is smaller (roughly half) than that obtained upon anodic polarization in a classical electrochemical promotion experiment can be then easily explained. 

G. Foti, F. Bokeloh, and C. Comninellis, Electrochemical promotion of bipolar electrodes An estimation of the current bypass, Electrochim. Acta 46, 357-363 (2000). 

Another version of cell or group arrangement is that using bipolar electrodes (Eig. 18.1a). Here, combined electrodes are used One side of the electrode functions... 

FIGURE 18.1 (a) Bipolar electrode (i>) filter-press reactor (1) bipolar electrode (2) gas-... 

Male, Sprague-Dawley rats were implanted under pentobarbital anesthesia with a bipolar electrode in the right dorsal hippocampus for hippocampal stimulation and recording. Stainless steel screws were also placed over the contralateral frontal and parietal cortices for recording cortical seizure activity. The electrodes... 

Kossuth An electrochemical process for extracting bromine from brines. The cell had bipolar electrodes and no diaphragm. It was developed in Germany in 1897 but abandoned in favor of the Kubierschky process. See also Wunsche. 

Typical pilot process conditions are Reactor 4001 steel enamel tank. Electrolyzer -10 bipolar electrodes with a surface of 0.9 m2/300 A. A suspension of 1 kmol MnS04 H20 in 535 kg H2S04 [55-60%] at 85 °C is circulated from the tank to the electrolyzer. 

Characteristics of the industrial reactor 16 bipolar electrodes, total surface of 18.3 m2. Current 4000 A flow about 7001/h Mn2+ reaction mass at 80-85 °C. Yield about 90% Mn3+ [140]. Four technical cells are in operation [140b] with an output of 100 t/year. 

Fig. 12 Capillary gap cell (From Ref. [4]) 1 bipolar electrode plates,...

Fig. 2.2 Schematics of hydrogen production using an alkaline electrolyzer unit with bipolar electrode geometry.

A filter press arrangement incorporating perforated bipolar electrodes to allow flow channels is described in another Russian patent [140]. 

Fig. 9.20 Comb-type bipolar electrodes for zinc-chlorine batteries (a) bipolar stack (b) unit cell...

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