"Contaminant Transformation by Transition Metal Oxides"

The influence of iron (Fe) and manganese (Mn) (hydr)oxides on contaminant transformation and fate is far greater then their environmental prevalence. Their high reactive surface area and their presence as grain and fracture coatings in contact with groundwater enhance their reactivity. Additionally, Mn oxides are considered to be the strongest, naturally occurring oxidants and are capable of transforming a wide range of inorganic and organic substrates. Substrates affected by the presence of transition metal (hydr)oxides include toxic heavy metals and metalloids, such as arsenic and chromium, and numerous emerging organic contaminants, such as antibacterial agents and endocrine disruptors. Here we utilize traditional and in situ, quick-scanning X-ray absorption spectroscopy (XAS), and high resolution TEM in conjunction with wet chemical techniques to characterize the rates and mechanisms of As(III) and bisphenol A (BPA) oxidation by delta Mn(IV) oxide. We use similar techniques to examine the role of redox cycling in changing the reactivity of Fe (hydr)oxides with respect to common, redox active, inorganic contaminants. Our research demonstrates that an understanding of the rates, and mechanisms of contaminant transformation by transition metal oxides requires characterization of both the solid-phase and aqueous-phase products