Photoassisted dissolution of a colloidal manganese oxide in the presence of fulvic acid
The dissolution of a synthesized manganese dioxide by a well-characterized fulvic acid has been investigated over a range of reactant concentrations, pH, and illumination conditions, as have components of the overall dissolution process including fulvic acid and manganous ion adsorption to the oxide surface. The dissolution process is satisfactorily described by an initial rapid formation of a surface-located precursor complex followed by a slower intramolecular electron-transfer step resulting in Mn(II) formation at the oxide surface. Illumination by 365-nm light enhances the rate of electron transfer significantly, with an increase in first-order reduction rate constant from 0.31 min/sup -1/ (dark) to 0.55 min/sup -1/ (light at pH 4.00 and from 0.53 min/sup -1/ (dark) to 1.23 min/sup -1/ (light) at pH 7.10. Depending on the affinity of the oxide surface for manganous ion, a portion of the Mn(II) produced at the oxide surface will be rapidly released to solution, resulting in dissolution of the oxide.
- Research Organization:
- Australian Nuclear Science and Technology Organization, Menai
- OSTI ID:
- 6606818
- Journal Information:
- Environ. Sci. Technol.; (United States), Vol. 22:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
FULVIC ACIDS
CHEMICAL REACTIONS
MANGANESE OXIDES
DISSOLUTION
ELECTRON TRANSFER
PH VALUE
PHOTOCHEMISTRY
CHALCOGENIDES
CHEMISTRY
MANGANESE COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
520200* - Environment
Aquatic- Chemicals Monitoring & Transport- (-1989)
400500 - Photochemistry