Ferrocyanide, current-voltage

In Figure 2 we show the equivalent results with a reasonably effective stabilizing agent, ferrocyanide, present. In this figure we show results with HF present (no oxide) for comparison as curve (d). The first cycle of a freshly etched electrode in the 0,1 M potassium ferrocyanide/water solution is indicated in the current/voltage characteristics as curve (a). Now in curve... 

Figure 16 shows the theoretically predicted influence of the normalised frequency, f, on the phase angle between current and voltage, , along with experimental verification [70] using the ferri-ferrocyanide reversible couple... 

FIGURE 8.4 PHSS polarogram. A representative graph of PHSS current obtained for separate 20 pM sulfide samples as a function of polarizing voltage under anoxic conditions. Signal was stable between 100 and 200mV as the ferricyanide to ferrocyanide ratio remained near unity (after [41]). 

Ferrous iron in the anolyte is oxidized to Fe " by dissolved chlorine. Since the solubility product of ferric hydroxide is very small ( 10 ), iron deposits on the membrane surface before it can penetrate the membrane. Iron, therefore, does not affect the selectivity of the membrane but may increase the voltage drop by reducing the effective area. Nickel has similar effects. Iron is generally less harmful because of very low solubility. However, it was reported [109] that in the presence of iron contamination, the current efficiency of Asahi Chemical cells with Aciplex membranes decreased by 2%. The cell voltage, on the other hand, was unaffected over 50 months of operation. The source of the iron was potassium ferrocyanide, an anticaking agent in the evaporated salt used as the raw material. 

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