Redox reactions manganese

Estuaries, in contrast, appear to be important sites for manganese redox reactions. Manganese maxima have been observed in several estuaries [421-423]... 

Bartlett, R.J., Manganese redox reactions and organic interactions in soils, in Manganese in soils and plants, Graham, R.D., Hannam, R.J., and Uren, N.C., Eds., Kluwer, Dordrecht, 1988, p. 59. 

The conversion of hydroperoxide/peroxide to superoxide is a one-electron redox reaction and requires the presence of transition metals having accessible multiple oxidation states as in biological iron or manganese clusters (e.g., Fe(II, III, IV) clusters of monooxygenase or the Mn(II, HI, IV) clusters of photosystems). Ti is usually not reduced at ambient temperatures. The various possibilities that could facilitate the transformation of hydroperoxo/peroxo to superoxo species are as follows ... 

Redox Reactions of Iron and Manganese at the Oxic Anoxic Boundary in Waters and Soils... 

Adsorption may influence precipitation by means other than the processes mentioned above. Davies (Chapter 23) discusses the role of the surface as a catalyst for oxidation of adsorbed Mnz+. Redox reactions may contribute substantially to the formation of manganese oxide coatings on mineral surfaces in soils and sediments. 

Chemical/Physical. Alkali or alkaline earth metals dissolve in aniline with hydrogen evolution and the formation of anilides (Windholz et ah, 1983). Laha and Luthy (1990) investigated the redox reaction between aniline and a synthetic manganese dioxide in aqueous suspensions at the pH range 3.7-6.5. They postulated that aniline undergoes oxidation by loss of one electron forming cation radicals. These radicals may undergo head-to-tail, tail-to-tail, and head-to-head... 

It should be noted that nonmetallic redox reactions also experience the sonication influence. The preparation of y lactons from olefines by oxidation of manganese triacetate is an example. 

OXII is responsible for the production of molecular oxygen in photosynthesis. A manganese complex, probably with four atoms of manganese, is attached to a protein molecule. It reduces OXjj which is recycled for use by another excited chlorophyll molecule in PS-II. In the redox reaction the manganese shuttles between two oxidation states with each manganese atom... 

We have used the reaction of m-chloroperbenzoic acid with Co/Mn/Br as a model system to attempt to understand the nature of this important autoxidation catalyst. Using stopped-flow and UV-VIS kinetic techniques, we have determined the step-wise order in which the catalyst components react with each other. The cobalt(II) is initially oxidized to Co(III) by the peracid, the cobalt(III) then oxidizes the manganese to Mn(III), which then oxidizes the bromide. The order of these redox reactions is the opposite to that expected from thermodynamics. Suggestions will be made of the relationship of this model to the known characteristics of autoxidation processes. 

In direct as well as in indirect electrolyses the burden for the environment by spent reagent is very small. In homogeneous redox reactions with stoichiometric quantities of the reagent, it is intolerably high in most cases. For example, it is unthinkable nowadays to dump spent manganese(II) or chromium(III). 

In the previous section it was shown how alkaline conditions could arise from interactions between sulfides and manganese oxides. Indeed, many redox reactions have a pH-controlling tendency. A general survey of the oxidizers and reducers that are available for exogenic and meta-morphic processes is therefore of interest. 

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