Silver anodic behaviour

Birss V I and Smith C K 1987 The anodic behaviour of silver in chloride solutions-l. The formation and reduction of thin silver chloride films Electrochim. Acta 32 259-68... 

Silver chloride is a common source and intermediate product in many extractive metallurgical processes, for example it occurs in the anode slimes from copper refineries, the residues of leaching processes for base metals, as a product of the chlorination of impure gold—silver bullion, and in photographic waste. A novel process for the leaching and purification of silver chloride, which was devised by Parker et a/.,26 is based on the observation that silver chloride is very soluble in some dipolar aprotic solvents containing chloride ion but is much less soluble when water is present. The very different behaviour of the equilibrium... 

VS. SCE, measured by the ratio of the SERRS band intensities at 1370 cm Fe(III) and 1360 cm Fe(II) agrees with the average of the anodic and cathodic potentials (—0.72 V and —0.58 V), see Fig. 30, 31. Furthermore, the irreversible character of the cyclic voltammetric redox process at a silver electrode, characterized by a potential peak separation larger than 0.06 V can also be illustrated by the non-Nem-stian behaviour of the ratio of the RR band intensities. This behaviour may reflect differential rates of adsorption and desorption of the oxidized and reduced species. 

In addition, electrooxidation of cystine and cysteine at platinum and gold electrodes has been described [158-160]. All a-amino acids have been found oxidizable at solid metal electrodes at approximately the same potentials [161, 162]. This oxidation leads to the formation of an imine intermediate, which is further oxidized to nornitril. At a silver electrode slow hydrolysis of this intermediate to noraldehyde also takes place. The electrochemical oxidation reactions of a- and jS-alanine at a platinum electrode in aqueous solutions produce free radicals accompanied by a second reaction involving loss of CO2 [163]. In the electrooxidation of a-alanine, the adsorbed intermediate species is either hydrolyzed anodically to acetaldehyde and ammonia, or is oxidized to a carbonium ion which is subsequently hydrolyzed to acetaldehyde and ammonia in solution, analoguous to the behaviour of glycine [164]. The mechanism for jS-alanine is similar except carbonium ion formation is accompanied by a hybrid transfer to form acetaldehyde. 

Comparatively little work on copper batteries has been reported. The substitution of silver by copper in RbAg I does not exceed 0.34 wt % and cells of/this electrolyte with copper anodes behaved in an unstable fashion. Preliminary cell measurements have also been reported using NN dimethyl triethylene-d gj ne dibromide - cuprous bromide in conjunction with copper anodes. With charge transfer complex cathodes (Br -perylene, iodine-perylene) the cells were unstable as the halogen oxidised the CuBr (or Cul) reaction product to the Cu state. With a stable behaviour was observed. 

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