共沉淀
锰
氧化还原
材料科学
化学
冶金
无机化学
出处
期刊:Advances in chemistry series
日期:1980-11-01
卷期号:: 45-72
被引量:28
标识
DOI:10.1021/ba-1980-0189.ch003
摘要
A nonequilibrium thermodynamic model for precipitation and oxidation of naturally occurring manganese oxyhydroxides in aqueous systems postulates the maintenance of reaction affinities simultaneously favorable for both the precipitation of Mn3O4 and its disproportionation to MnO2 and Mn2+(aq). Experimental data show changes with pH in the MnO2-H+ stoichiometry that are explainable by the model. A solid-solution model can be used to predict the state of oxidation of manganese in mixed-valence oxide, based on pH and Mn2+(aq) activity in associated solutions. Both lead and cobalt raise the oxidation state of manganese oxides when coprecipitated at pH 8 and 8.5. Coupling of lead and cobalt redox processes to Mn3O4 disproportionation provides a model that can be used to predict the range of activity of these metals likely to occur in systems where manganese oxides are precipitating.
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