Chemistry of colloidal manganese dioxide. 1. Mechanism of reduction by an organic radical (a radiation chemical study)

Journal Article · Thu Dec 19 04:00:00 EST 1985 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100272a040· OSTI ID:6035354

Lume-Pereira, C; Baral, S; Henglein, A; Janata, E

Transparent sols of manganese(IV) oxide and manganese(III) oxide were prepared by ..gamma..-irradiating solutions of potassium permanganate. The reaction of radiolytically produced 1-hydroxy-1-methylethyl radicals, (CH/sub 3/)/sub 2/COH, with the MnO/sub 2/ colloid was investigated by recording the accompanying changes in optical absorption and conductivity. The yield of reduction is 5.7 MnO/sub 2/ molecules reduced per 100 eV. Electron transfer to the colloidal particles leads to the release of OH/sup -/ ions, depending on the pH and the degree of reduction. Mn/sup 3 +/ centers are formed in the reduction which accelerates the reaction of the radicals. A fast conproportionation reaction between Mn/sup 2 +/ and Mn/sup 4 +/ centers at the surface of the colloidal particles is postulated in alkaline sols. A strong accumulation of Mn/sup 3 +/ centers thus is achieved. In acidic solutions, the Mn/sup 3 +/ centers disproportionate. Mn/sup 3 +/ centers also are formed when Mn/sup 2 +/ ions are added to a MnO/sub 2/ sol of pH > 4. It is also pointed out that the absorption spectra of colloidal and macrocrystalline MnO/sub 2/ are distinctly different. 19 references, 14 figures, 1 table.

• Research Organization: Hahn-Meitner-Institut fuer Kernforschung Berlin, West Germany
• OSTI ID: 6035354
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 89:26; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ALKALI METAL COMPOUNDS
ALKYL RADICALS
CHALCOGENIDES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
COLLOIDS
DATA
DECOMPOSITION
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELECTRON TRANSFER
ETHYL RADICALS
EXPERIMENTAL DATA
GAMMA RADIATION
HYDROXYL RADICALS
INFORMATION
IONIZING RADIATIONS
MANGANESE COMPOUNDS
MANGANESE OXIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PERMANGANATES
POTASSIUM COMPOUNDS
POTASSIUM PERMANGANATES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
TRANSITION ELEMENT COMPOUNDS