Surface Redox Potential Research Articles

Das Redoxverhalten von Bisbiphenylchrom(I)-jodid in Wasser

Bisbiphenylchromiumiodide [BBCr(I)J] is widely used as a “reference ion” in comparing redox potentials in different solvents. The voltametric behaviour in aqueous solutions however, is complicated by adsorption phenomena of the oxidized as well as the reduced form. Classical polarography, A—C polarography, cyclic voltametry, large scale electrolysis and pulsevoltametric methods have been employed to obtain information about the nature of the electrode reaction, its reversibility and the solubility of the reactants. Based on these data it is shown that the formal standard redox potential corresponds to the reactionBBCr(I)ads/BBCr(O)ads and has to be regarded as a “surface redox potential”.

The mechanism of the adsorption of alkyl xanthate species on galena

AbstractOxidation of galena produced thiosulphate and sulphate ions at the mineral surface but flotation activity, using isopropyl xanthate as collector, was found to depend on the concentration of thiosulphate ions at the surface. It is proposed that the thiosulphate ion reacts with di‐isopropyl dixanthogen formed by oxidation of xanthate ion in solution. It was demonstrated that these species react in homogeneous solution to give xanthate and xanthogen‐thiosulphate ions. The proposed surface reaction may account for the formation of a layer of adsorbed xanthate ions and for the surface redox potential being raised to a value where more xanthate ions can be chemisorbed and where dixanthogen is stable.