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Spectroscopic Study of Surface Redox Reactions with Manganese Oxides
Author(s) -
Risser Jeffrey A.,
Bailey George W.
Publication year - 1992
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1992.03615995005600010013x
Subject(s) - redox , manganese , chemistry , phase (matter) , metal , spectroscopy , inorganic chemistry , absorbance , chemical engineering , organic chemistry , physics , chromatography , quantum mechanics , engineering
Redox reactions involving soil minerals and materials are important processes in environmental chemistry, but unfortunately they only have been characterized in the solution phase. The lack of a suitable method has prevented investigations of the mineral surface component of redox reactions. We present a model system in which ultraviolet‐visible spectroscopy is employed to observe a surface redox reaction. A synthetic MnO x is reacted with Cr(III), resulting in Cr oxidation to the hexavalent state and the reduction of the MnO x mineral. A scattered transmission accessory allowed us to observe spectroscopically both the appearance of Cr(VI) and the attenuation of MnO x in a suspension. Loss of absorbance intensity by MnO x suspensions may be useful as a general method to follow redox reactions as a function of the solid phase rather than relative to a specific reactant. This spectroscopic approach provides the capability to monitor in situ reactions of solid‐phase components and is useful for examining transformations of metallic and organic wastes and naturally occurring materials in the environment.