Birnessites are ubiquitous components of natural systems and may exert a significant influence on the mobility and toxicity of environmental contaminants, of both inorganic and organic origin. Their small particle sizes and internal structure provide them with high sorption capacities and oxidizing abilities towards redox sensitive species. In the present work we show reactivity differences between two synthetic Mn(IV) birnessites of different particle sizes, identified previously as close structural analogs of biogenic Mn oxides. These layered Mn(IV) oxides not only sorb ionic species, but also may adsorb and even oxidize hydrophobic compounds. Differences in specific surface area of the birnessites studied have evident influences on their adsorption and oxidation behavior. However, equally important and unexpectedly, their differences in internal vacancy contents exert a strong influence on external surface-mediated processes. Illustrative case studies on adsorption and oxidation of arsenic and polycyclic aromatic hydrocarbons will be presented.

Influence of particle size and structure on the adsorption and oxidation behavior of Mn(IV) birnessites

247th National Meeting (2014)

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