Cation, increased concentration oxidizing action

However, the pH is not sufficient in order to predict the corrosion resistance of a metal or an alloy in aqueous solution. The nature of the acid (and thus of the anion associated with the proton H ) and of the base (and thus of the cation associated with OH ) also need to be taken into account. For example, mineral acids such as hydrochloric acid strongly attack aluminiiun. The rate of attack increases with concentration. On the other hand, concentrated nitric acid does not react with aluminium. Due to its oxidative action, it even... 

Other cationic surfactants such as TTAB, DTAB, DODAB, STAC, CEDAB, and DDDAB have been used in CL reactions with less frequency. Thus, tetradecyltrimethylammonium bromide [TTAB] has been used to increase the sensitivity of the method to determine Fe(II) and total Fe based on the catalytic action of Fe(II) in the oxidation of luminol with hydrogen peroxide in an alkaline medium [47], While other surfactants such as HTAB, hexadecylpiridinium bromide (HPB), Brij-35, and SDS do not enhance the CL intensity, TTAB shows a maximum enhancement at a concentration of 2.7 X 10 2 M (Fig. 11). At the same time it was found that the catalytic effect of Fe(II) is extremely efficient in the presence of citric acid. With regard to the mechanism of the reaction, it is thought that Fe(II) forms an anionic complex with citric acid, being later concentrated on the surface of the TTAB cationic micelle. The complex reacts with the hydrogen peroxide to form hydroxy radical or superoxide ion on the... 

Coexistence of the Hf(II) complexes in the melt and a small fi-action of Hf(IV) can be positive factors since, in the presence of cations of different degrees of oxidation, the stability of the plane crystallization fi-ont increases [10]. However, a shortcoming of this electrolyte is that it tends towards disproportionation. For example, at Hf(II) concentrations greater than 6 10 mol/cm the following reaction was observed to occur [8] ... 

Taking into account the penetration power of a natural oxide film by anions, in particular chlorides, the density and depth of pitting generally increases with increasing chloride concentration (Figure D.1.6). The action of chlorides is independent of the action of the associated cation (or cations, if several are present). 

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