Iron oxyhydroxide, a-FeOOH, plays a critical role in geochemical and atmospheric processes including as a potential source of iron in the open oceans as well as a reactive component of dust. In this study, we combine dissolution measurements along with spectroscopy and microscopy to focus on nanoscale size effects in surface adsorption of polyatomic oxyanions and iron dissolution in iron oxyhydroxide minerals from gas-phase precursors (like nitric) and as aqueous phase ions. In liquid-phase studies of oxyanions, including phosphate and carbonate, nanorods showed a higher surface adsorption of these anions compared to microrods. These differences are attributed to the presence of more reactive (021) faces with higher surface �OH group density in nanorods compared to microrods. However, in gas phase studies, nitric acid uptake leading to adsorbed nitrate yields a saturation coverage of nitrate on microrods higher than that on nanorods, an interesting size effect which is attributable to surface structural changes that occur as a function of particle size during the reaction.

Size-dependent behavior of iron oxyhydroxide minerals: Surface adsorption and iron dissolution in the presence of polyatomic oxyanions

243rd National Meeting (2012)

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