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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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Journal ArticleDOI
TL;DR: In this paper, the effects of silica and carbon supports on the structure and catalytic performance of iron catalysts for high temperature Fischer-Tropsch synthesis were investigated and the results showed that the performance of the catalysts depended on iron phase composition rather than on iron dispersion.
Abstract: The paper addresses the effects of silica and carbon supports on the structure and catalytic performance of iron catalysts for high temperature Fischer-Tropsch synthesis. Iron phase composition and dispersion in both calcined and activated catalysts were strongly affected by the support. Hematite was the major iron phase in calcined silica supported catalysts, while carbon supported counterparts contain magnetite. Catalyst activation in carbon monoxide leads to carbidisation of iron oxides to principally Haag iron carbide. Higher Fischer-Tropsch reaction rates were observed on carbon supported iron catalysts compared to silica supported counterparts. The catalytic performance principally depended on iron phase composition rather than on iron dispersion. Iron catalysts supported on carbon nanotubes and activated carbon showed highest activity in Fischer-Tropsch, which could be attributed to the formation of composites of iron carbide and residual magnetite.

92 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of mineral surface structure on the rate of electron transfer from Shewanella oneidensisstrain MR-1 outer membrane proteins to the mineral surface and the subsequent effect upon cell activity was investigated.

92 citations

Journal ArticleDOI
15 Oct 1996
TL;DR: In this article, the synthesis of colloidal polypyrrole-magnetite-silica nanocomposites is described, where pyrrole is chemically polymerized using (NH4)2S2O8, H2O2/Fe3+/HCl, or FeCl3oxidants in the presence of these silica-coated magnetite particles.
Abstract: The synthesis of colloidal polypyrrole–magnetite-silica nanocomposites is described. First, silica-coated magnetite particles were prepared by the aqueous deposition of silica onto ultrafine (5–20 nm) magnetite particles via controlled hydrolysis of sodium silicate. Then pyrrole was chemically polymerized using (NH4)2S2O8, H2O2/Fe3+/HCl, or FeCl3oxidants in the presence of these silica-coated magnetite particles to yield colloidal dispersions of polypyrrole–magnetite–silica particles. The magnetite contents of these materials were as high as 17.5% by mass. Vibrating sample magnetometry measurements confirmed that these nanocomposites were superparamagnetic, with bulk saturation magnetization values of up to 10.9 emu g−1. Disc centrifuge photosedimentometry was used to assess particle size and degree of dispersion, yielding weight-average particle diameters in the range 100–520 nm. Electron microscopy studies indicated a rather ill-defined particle morphology but provided some evidence for the magnetite component within the nanocomposites. Stable colloidal dispersions were obtained using the H2O2/Fe3+/HCl and (NH4)2S2O8, oxidants, whereas FeCl3-based syntheses yielded only flocculated particles or macroscopic precipitates under similar conditions. Solid-state electrical conductivities of nanocomposites synthesized using (NH4)2S2O8, H2O2/Fe3+/HCl, and FeCl3were about 10−3, 10−2, and 10−1S cm−1, respectively.

91 citations

Journal ArticleDOI
TL;DR: In this paper, an analysis of the Mossbauer parameters of the Pb-promoted catalysts shows that lead enters the spinel structure as Pb 4+ on tetrahedral sites, giving rise to a partly normal spinel.

91 citations

Journal ArticleDOI
TL;DR: Zinc-facilitated adsorption provides further advantage for magnetite nanoparticle-enhanced arsenic removal over conventional treatment approaches, and can be significantly enhanced with trace amount of Zn(2+) due to the formation of a ternary complex.

91 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023570
20221,277
2021367
2020478
2019494
2018446