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Abstract  

A series of catalysts prepared by dispersing iron oxide on supports of different nature and acidity has been studied. Silica (S) and silica-zirconia mixed oxides (SZ) with different ZrO2 content (from 5 to 45 mass%) were used as supports for the iron oxide phase which was deposited over them by an equilibrium-adsorption method. The red-ox properties of the Fe-catalysts were studied by temperature programmed reduction (TPR) technique. The two well defined and narrow TPR peaks observed could be associated with the reduction steps: I) Fe2O3→FeO and Fe2O3→Fe(0) (at ca. 400°C) and II) FeO→Fe(0) (at ca. 800–900°C). The temperature of the second-step-peak increased with the zirconia content in the support, likely because of the stronger interaction of the iron oxide phase with the support. Activation parameters for the two step-reduction processes were obtained by a simple computation procedure applied to the TPR profiles.

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Abstract  

This paper reports on the synthesis of various iron oxides by the IR laser processing of different iron salts. X-ray diffraction techniques were used to characterize the reaction products. Some differences in terms of crystallite size and isotropy between these oxides and those obtained from the same salt by thermal means are described and explained.

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Journal of Flow Chemistry
Authors: Matthew Simmons, Charlotte Wiles, Vincent Rocher, M. Grazia Francesconi, and Paul Watts

; Hill , M. R. ; Harris , R. ; Muster , T. H. J. Magn. Magn. Mater . 2009 , 321 , 2677 – 2681 . 25. Cornell , R. M. ; Schwertmann , U. The Iron Oxides: Structure, Properties

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Low temperature reactivity in agglomerates containing iron oxide

Studies in the Ca(OH)2–C–Fe2O3 system

Journal of Thermal Analysis and Calorimetry
Authors: Ryan Robinson, Fabrice Patisson, and Bo Björkman

these dusts have shown to result in several industrial benefits, mostly in the decrease of natural resource dependence, reduction of landfill, and indirectly as energy savings [ 2 ]. These by-product dusts contain considerable amounts of iron oxides

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Introduction Among various metal oxide catalysts, iron oxides have attracted much attention in recent years due to their structural characteristics and physico-chemical properties [ 1 – 5 ]. Besides their catalytic potential

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Summary  

The removal of uranium (VI) from zerovalent iron permeable reactive barriers and wetlands can be explained by its association with iron oxides. The long term stability of immobilized U is yet to be addressed. The present study investigates the remobilization of U(VI) from iron oxides via diverse reaction pathways (acidification, reduction, complex formation). Prior, uranium coprecipitation experiments were conducted under various conditions. The addition of various amounts of a pH-shifting agents (pyrite), an iron complexing agent (EDTA) or iron (III) reduction agent (TiCl3) yielded in uranium remobilization, concentrations above the US EPA allowedmaximum contaminant level(MCL=30 µg/l). This study demonstrates that U(VI) release in nature strongly depends on the conditions and the mechanism of its fixation by geological materials.

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Abstract  

Composite SiO2—iron oxide materials were prepared by three experimental procedures. In the first case, the iron oxides were precipitated during a sol-gel process. In the second case, a SiO2 matrix was initially obtained, and the iron oxides were formed by thermal treatment after impregnation of a soluble Fe2+ salt in the previously processed matrix. In the third method, ferrite powders, prepared by wet chemical method, were embedded into a SiO2 based sol-gel matrix. Materials with convenient porosity and nano-sized iron oxide content could be prepared using the mentioned methods. The prepared composite has been tested for arsenic(V) removal.

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Journal of Thermal Analysis and Calorimetry
Authors: Marilda Vianna, Jo Dweck, Frank Quina, Flavio Carvalho, and Claudio Nascimento

Abstract  

Commercial bentonite (BFN) and organoclay (WS35), as well as iron oxide/clay composite (Mag_BFN) and iron/oxide organoclay composite (Mag_S35) were prepared for toluene and naphthalene sorption. Mag_BFN and Mag_S35 were obtained, respectively, by the precipitation of iron oxide hydrates onto sodium BFN and S35 clay particles. The materials were characterized by powder X-ray diffraction (XRD), X-ray Fluorescence (XRF), and TG and DTA. From XRF results and TG data on calcined mass basis, a quantitative method was developed to estimate the iron compound contents of the composites, as well as the organic matter content present in WS35 and Mag_S35.

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Abstract  

Factors that influence the adsorption of trace elements or radionuclides on hydrous iron oxides were investigated. The adsorption of monovalent cations (Cs+, Rb+) on hydrous iron oxides is not strongly pH-dependent and it can be regarded as nonspecific. On the other hand, the adsorption of Ag+, divalent cations (Zn2+, Cd2+, Mn2+, Sr2+) or trivalent cations (Cr3+, La3+, Ce3+, Eu3+, Gd3+, Er3+, Yb3+) is strongly pH-dependent. The regularities of the adsorption of these cations on hydrous iron oxides are discussed. Also, the differences in the adsorption behaviour of some divalent and trivalent cations are explained. Freshly precipitated iron(III) hydroxide can be used for the decontamination of radionuclides from low-level waste solutions. However, the efficacy of decontamination depends on the oxidation state and the chemical properties of radionuclides.

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Journal of Thermal Analysis and Calorimetry
Authors: Marilda Vianna, Jo Dweck, Frank Quina, Flavio Carvalho, and Claudio Nascimento

Abstract  

This study investigates the sorption of toluene and naphthalene by a sodium bentonite (BFN), an organoclay (WS35) and by their respective iron oxide hydrate composites Mag_BFN and Mag_S35. The organic matter content of WS35 and Mag_S35, determined by thermogravimetry, was used to obtain their organic matter sorption coefficients, which show that they are effective sorbents to remove organic contaminants from water, with a higher selectivity for naphthalene than for toluene sorption. The main iron oxide phase present in Mag_BFN and Mag_S35 is maghemite (γ-Fe2O3), which allows these sorbents to be separated from the effluent by a magnetic separation process after use.

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