Kinetics of reductive dissolution of colloidal manganese dioxide

Journal Article · Thu Oct 18 04:00:00 EDT 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100384a063· OSTI ID:6044298

Mulvaney, P; Cooper, R; Grieser, F ^[1]; Meisel, D ^[2]

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1. Univ. of Melbourne, Victoria (Australia)
2. Argonne National Lab., IL (USA)

The temporal characteristics of electron transfer to and proton uptake by colloidal manganese oxides in acidic aqueous solutions have been examined in the time regime of milliseconds to tens of seconds. Time-resolved conductometric measurements coupled with electron-transfer-rate results indicate that electron deposition into the colloidal oxides and protonation occurs simultaneously; i.e., there is no polarization of the colloid during the reduction process. Reduction of the manganese oxides leads to their dissolution with quantitative amounts of Mn(II) produced in the bulk aqueous phase. A detailed examination of both thermal- and radiation-induced dissolution of the metal oxides indicates that Mn(III) centers present in the colloid are continually depleted to produce Mn(II). The driving force for this reaction is the chemical potential gradient between the colloid and the aqueous solution due to the homogeneous nature of mixed Mn(IV)/Mn(III) oxides. Equilibrium between the solution and the colloid is established in both acidic and alkaline solution by either conproportionation or disproportionation of Mn(III) depending only on pH or pMn.

• OSTI ID: 6044298
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:21; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ABSORPTION SPECTRA
AQUEOUS SOLUTIONS
CHALCOGENIDES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
COLLOIDS
DATA
DECOMPOSITION
DISPERSIONS
ELECTRON TRANSFER
EXPERIMENTAL DATA
INFORMATION
KINETICS
MANGANESE COMPOUNDS
MANGANESE OXIDES
MEASURING METHODS
MIXTURES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIOLYSIS
REACTION KINETICS
SOLUTIONS
SPECTRA
TRANSITION ELEMENT COMPOUNDS