Novel double-shelled hierarchical ferrihydrite hollow spheres (Fe(10)O(14)(OH)(2).4H(2)O) were successfully synthesized on a large scale by using a facile medicine-inspired solution-phase approach. Sodium nitroprusside (SNP), an ordinary and inexpensive medicine for expanding blood vessels, served as both a ferric source and an in situ formed gas-bubble template with the presence of sodium dihy...

Differential pair distribution function (d-PDF) analysis of high energy powder X-ray diffraction data was carried out on 2-line ferrihydrite nanoparticles with arsenate oxyanions adsorbed on the surface to investigate the binding mechanism. In this analysis, a PDF of ferrihydrite is subtracted from a PDF of ferrihydrite with arsenate sorbed on the surface, leaving only correlations from within ...

During deposition of Precambrian iron formation, the combined sedimentation of ferrihydrite and phytoplankton biomass should have facilitated Fe(III) reduction during diagenesis. However, the only evidence for this reaction in iron formations is the iron and carbon isotope values preserved in the authigenic ferrous iron-containing minerals. Here we show experimentally that spheroidal siderite, ...

Phosphorus affects the sorption of many metals and arsenate to iron (hydr)oxides. This may influence the mobility and bioavailability of metals and arsenate in soil and water. Phosphorus therefore plays an important role in, e.g., determining the ecotoxicological risk of contaminants in soils. The overall aim of this thesis was to improve the understanding of lead(II), copper(II), cadmium(II) a...

Many physical and chemical processes control the extent of Fe(III) oxyhydroxide reduction by dissimilatory Fe(III)-reducing bacteria. The surface precipitation of secondary Fe minerals on Fe(III) oxyhydroxides limits the extent of microbial Fe(III) reduction, but this phenomenon has not yet been observed in nature. This paper reports the observation of secondary Fe-mineral (goethite) encrustati...

A mesophilic, anaerobic, gram-negative bacterium, strain SB164P1, was enriched and isolated from oxidized marine surface sediment with elemental sulfur as the sole energy substrate in the presence of ferrihydrite. Elemental sulfur was disproportionated to hydrogen sulfide and sulfate. Growth was observed exclusively in the presence of a hydrogen sulfide scavenger, e.g., ferrihydrite. In the abs...

Elevated antimony concentrations in aqueous environments from anthropogenic sources 9 is becoming of global concern, here iron oxides are known to strongly adsorb aqueous antimony 10 species with different oxidation states, but the effect of silica on the removal characteristics is not 11 well understood despite being a common component in the environment. In this study, ferrihydrite 12 was syn...

Despite the number of detailed studies on arsenate adsorption onto synthetic 2-line ferrihydrite carried out during the past few decades, questions remain regarding the fate of adsorbed arsenate during phase transformation of this poorly crystalline iron oxy-hydroxide. We assessed arsenate partitioning during this transformation by aging synthetic 2-line ferrihydrite with adsorbed arsenate (at ...

This study investigated several knowledge gaps with respect to the diffusive gradients in thin films (DGT) technique for measurement of oxyanions (As(III), As(V), Se(IV), Se(VI), PO4(3-), and V(V)) using the ferrihydrite and Metsorb™ binding layers. Elution efficiencies for each binding layer were higher with 1:20 dilutions, as analytical interferences for ICP-MS were minimised. Diffusion coeff...