Mechanistic interactions of phenolic contaminants and dissolved organic matter with manganese oxides

Abstract:

Manganese oxides are considered one of the strongest naturally-occurring oxidants in near surface environments. These minerals can oxidize several classes of inorganic and organic contaminants, including those with phenolic functional groups. As a result, manganese oxides such as MnO2 have been proposed for the passive, in-situ treatment of these pollutants in stormwater, landfill leachate, and other contaminated surface waters and may be a key driver of reactivity and contaminant fate in natural waters interfacing Mn-enriched soils. However, these surface waters have complex matrices containing a variety of organic contaminants and dissolved organic matter (DOM), which may interact with both the manganese surface and organic contaminants through sorption, redox reactions, complexation, and other mechanisms. This study evaluates the mechanisms by which these complex organic matrices alter the reactivity of manganese oxides as a factor of contaminant structure, manganese characteristics, and bulk DOM properties. The results of this study suggest that surface water complexities such as DOM mechanistically impact contaminant transformation by manganese oxides. These results could be applied to predict the relative changes in contaminant oxidation in differing surface water matrices and to explain the conflicting results of previous studies.