Reactivity of Interfacial Iron Species on Mineral Colloids
Iron-containing minerals are naturally abundant and they represent an important class of reactive solids in the aquatic environment. Ample studies have been conducted focusing on the reactivity of single-phase iron oxides, however, mineral colloids such as alumina, silica, or aluminosilicates deposited with a thin layer of molecular iron species are less well understood. These iron-laden surfaces arise ubiquitously in the aquatic environment, particularly near redox transition zones.
Our current research efforts center on elucidating the surface chemistry and redox activity of iron anchored on two model mineral substrates, silica and alumina. The redox activity of these iron-deposited surfaces is assessed in two reaction systems, namely activation of environmental oxidants (e.g., hydrogen peroxide) for oxidation of organic carbons, and surface-mediated redox transformation of metalloid contaminants (e.g., arsenic). We take a multi-pronged approach combining conventional aqueous chemistry investigations and surface/solid characterization techniques (e.g., electron microscopy, XRD, XPS, DR UV-Vis, and Mössbauer spectroscopy) to dissect complex interactions in these heterogeneous systems.