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Magnetite
About: Magnetite is a research topic. Over the lifetime, 10277 publications have been published within this topic receiving 278071 citations.
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TL;DR: In this article, the speciation and grain size distribution of iron have been examined in several riverine and glacial sediments, in order to evaluate controls on the concentrations and modes of occurrence of iron oxides in weathering-derived particulates.
157 citations
TL;DR: Stochichiometric magnetite, in the absence of aqueous Fe(II), can rapidly reduce nitrobenzene and it is speculated that contaminant reduction that was previously attributed to Fe( II) sorbed on magnetite is due to a process similar to negative (n) doping of a solid, which increases the stoichiometry of the magnetite and alters the bulk redox properties of the particle to make reduction more favorable.
Abstract: Magnetite (Fe3O4) is a common biomineralization product of microbial iron respiration and is often found in subsurface anoxic environments, such as groundwater aquifers where aqueous Fe(II) is present We investigated the reaction between aqueous Fe(II) and magnetite using the isotopic selectivity of 57Fe Mossbauer spectroscopy and revisited the reduction of nitrobenzene by magnetite. Similar to our previous findings with Fe3+ oxides, we did not observe the formation of a stable sorbed Fe(II) species; instead, we observed oxidation of the Fe(II) to a partially oxidized magnetite phase. Oxidation of Fe(II) was accompanied by reduction of the octahedral Fe3+ atoms in the underlying magnetite to octahedral Fe2+ atoms. The lack of a stable, sorbed Fe(II) species on magnetite prompted us to reevaluate what is controlling the extent of Fe(II) uptake on magnetite, as well as contaminant reduction in the presence of magnetite and Fe(II). Uptake of Fe(II) by magnetite appears to be limited by the stoichiometry of the magnetite particles, rather than the surface area of the particles. More oxidized (or less stoichiometric) magnetite particles take up more Fe(II), with the formation of stoichiometric magnetite (Fe2+/Fe3+ = 0.5) limiting the extent of Fe(II) uptake. We also showthat stoichiometric magnetite, in the absence of aqueous Fe(II), can rapidly reduce nitrobenzene. Based on these results, we speculate that contaminant reduction that was previously attributed to Fe(II) sorbed on magnetite is due to a process similar to negative (n) doping of a solid, which increases the stoichiometry of the magnetite and alters the bulk redox properties of the particle to make reduction more favorable.
157 citations
157 citations
TL;DR: The aging effects of nZVI, prepared using a borohydride reduction method in static water over a period of 90 days (d), are investigated and the patterns of occurrence of specific iron oxides in different natural conditions are explained.
156 citations
TL;DR: The distinctive structure and the heavy metal ions removal property of magnetic nanocomposites reflect their prospective application in water treatment.
156 citations