The role of Fe oxyhydroxide coating, illite clay, and peat moss in nanoscale titanium dioxide (nTiO) retention and transport in geochemically heterogeneous media.

Natural media such as soil and sediment contain mineralogical and organic components with distinct chemical, surface, and electrostatic properties. To better understand the role of various soil and sediment components on particle transport, columns were packed with quartz sand and natural sediment with added Fe oxyhydroxide coating, illite clay, and peat moss to investigate how these added components influence nTiO retention and transport in geochemically heterogeneous medium. Results showed that nTiO transport was low at pH 5, attributable to the electrostatic attraction between positively-charged nTiO and negatively-charged medium.

Fine particle attachment to quartz sand in the presence of multiple interacting dissolved components.

In natural aquatic systems water chemistry is complicated and fine particles encounter multiple water components simultaneously, yet the combined effects of some multiple components on the fate and transport of these particles have not been elucidated. In this study nTiO and illite colloid attachment to quartz sand was investigated in 1 mM NaCl and 0.5 mM CaCl background solutions using a range of phosphate concentrations (0 to 10 mg/L) at pH 5 and 9.

Cu and Zn adsorption to a heterogeneous natural sediment: Influence of leached cations and natural organic matter.

Adsorption of heavy metals by natural sediments has important implications to the fate and transport of contaminants in subsurface environments. Although the importance of major multivalent cations and dissolved organic matter (DOM) in heavy metal adsorption had been previously demonstrated, the leaching of major cations and DOM from sediments and its influence on heavy metal adsorption have not been fully examined. In this study, the concentrations of Ca, Mg, Al, Fe, and natural organic matter that leached from a natural sediment in Cu and Zn adsorption experiments were measured and used in surface complexation models to elucidate their effects on Cu and Zn adsorption.