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Arsenic sorption onto natural hematite, magnetite, and goethite

2007.3.22  Natural hematite, goethite, and magnetite are suitable agents to remove both As(III) and As(V) from solutions, being natural hematite the solid that presents the

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Characterization of hematite (α‐Fe2O3), goethite

2006.12.16  Hematite and goethite have low spontaneous magnetizations and negligible magnetic interactions, while greigite and

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Authigenic magnetite formation from goethite and hematite

2018.3.8  Authigenic magnetite formed from microcrystalline goethite and hematite dominantly behaves as interacting single-domain particles, while nanophase goethite

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Production and in situ transformation of hematite into magnetite

2019.8.5  The transformation of hematite to magnetite occurs at 623 K (for biomass/nitrate mixture) and 723 K (for biomass/goethite mixture). The formation of

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Comparison of magnetite, hematite and goethite

2023.4.25  The characteristics and mechanism of phosphate adsorption onto magnetite, hematite and goethite were comparatively studied, and the effects of

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Thermomagnetic properties of the goethite transformation

2018.10.1  In this paper, transformations of synthetic goethite and brown goethite ore (Kerch iron ore basin) under oxidative (in air) and reducing (mixed with 4% of starch)

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Bulk and key surface structures of hematite, magnetite, and goethite

2009.10.1  The iron oxides hematite, magnetite, and goethite were studied with density functional theory to establish a consistent set of structures for both the bulk

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Goethite (gth/Nadeleisenerz) SpringerLink

2023.7.13  This chapter describes the common iron ore Goethite (abbrv. gth), as seen with optical, reflected light microscopy. After summing up compositional data, main

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Control of Earth-like magnetic fields on the transformation

2016.7.26  For fields below ~60 μT, hematite and goethite coexist. In contrast, above 60 μT, hematite is dominant and goethite is undetectable. Based on XRD results, we

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Characterization of hematite (α‐Fe2O3), goethite

2006.12.16  [1] First-order reversal curve (FORC) diagrams have become a standard tool in rock magnetism, yet magnetite is the only magnetic mineral that is well characterized using FORC diagrams. We

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Bulk and key surface structures of hematite, magnetite, and goethite

2009.10.1  Abstract The iron oxides hematite, magnetite, and goethite were studied with density functional theory to establish a consistent set of structures for both the bulk mineral and key surfaces, characterize surface relaxation, and predict and test calculated scanning tunneling microscopy (STM) images. Spinpolarized, plane-wave

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Arsenic sorption onto natural hematite, magnetite, and goethite

2007.3.22  A high sorption of both As (III) and As (V) on magnetite was observed by Parga et al. [19] when removing arsenic from a Mexican contaminated groundwater by using electrocoagulation. In this work, we have tested the sorption of arsenic on natural magnetite, hematite, and goethite in order to compare the sorption capacity of these minerals with ...

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Photoacoustic, EPR and electrical conductivity investigations of three ...

2002.5.1  The electrical conductivity (in logarithmic scale) of hematite, goethite and magnetite compounds dependence on temperature were shown in Fig. 2.For all samples, σ(T) increased strongly when increasing temperature within the studied temperature range.The results indicated that the materials were semiconductors.

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Bulk and key surface structures of hematite, magnetite, and goethite

2009.10.2  The iron oxides hematite, magnetite, and goethite were studied with density functional theory to establish a consistent set of structures for both the bulk mineral and key surfaces, characterize ...

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Transformation of various kinds of goethite into magnetite: Effect of ...

2013.4.1  Fe II-induced mineralogical transformations of three goethites (G1, G2 and G3), having different crystal habits, morphologies and surface properties, into magnetite were studied.Experimental data revealed that all estimated constants including kinetic rate constant of magnetite formation, first order rate constant of goethite reductive dissolution

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(IUCr) Misorientation relationships in goethite, hematite and magnetite ...

For magnetite this specific volume is equal to 18.476 Å 3, for hematite it is 16.818 Å 3 and for goethite 17.347 Å 3, i.e. the volume occupied by a single O in hematite is about 9% smaller than in the former magnetite, whereas the volume required for an O ion in goethite increases by about 3% compared with hematite. This probably explains ...

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Goethite Iron Oxide, Hematite, Limonite Britannica

Goethite is normally formed under oxidizing conditions as a weathering product of iron minerals (e.g., pyrite, magnetite). Because it is formed near the surface, goethite is the major component of the gossan of iron sulfide deposits in locations such as Arizona and of lateritic deposits in places such as Cuba.

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Arsenic sorption onto natural hematite, magnetite, and goethite

2007.4.1  In other studied on porous hematite. pHPZC also measured at level of 6 (Singh and Pant 2004) and the pHPZC are: magnetite 6.5; goethite, 6.8; hematite, 6.7 (Giménez et al. 2007; Kosmulski 2014). ...

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Sorption of silicates on goethite, hematite, and magnetite:

2007.8.15  Sorption of H 4 SiO 4 (including experiments as a function of time, K d measurement with different m / v ratios and sorption edges) onto different iron (hydro)oxides as goethite (α-FeOOH), hematite (α-Fe 2 O 3), and magnetite (Fe 3 O 4) has been studied with concentration of silicates under solubility limit.A surface complexation model has

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Replacement of magnetite by hematite in hydrothermal systems

2022.1.1  In the BSY-1 foil, hematite nanocrystals were identified by electron diffraction patterns in large pores (Fig. 2).Although some of them have an acicular morphology with a width up to 5 nm, no d-spacings of goethite can be found and indexed in the diffraction patterns (Fig. 2 d).The rest consists of island-like hematite nanocrystals

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The origin and stability of lunar goethite, hematite and magnetite

1972.12.1  Goethite is stable at low temperatures and pressures in almost pure H 2 -H 2 O gases. Its minimum stability against hematite is 2 bars total pressure at 130°C and 10 −3 bars at 30°C for H 2 to H 2 O ratios compatible with the high temperature redox state of lunar materials. Thus the traces of magnetite, hematite and goethite in lunar ...

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Thermomagnetic properties of the goethite transformation

2018.10.1  The transformation of goethite into hematite occurred at about 270 °C for the synthetic sample and at 310 °C for the natural brown sample. ... The incomplete transformation of natural goethite into magnetite can be explained by the complicated interaction between iron ions and reducing agent due to the larger particle size and the

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Spectral and other physicochemical properties of submicron powders

Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (α-Fe 2 O 3), maghemite (γ-Fe 2 O 3), magnetite (Fe 3 O 4), goethite (α-FeOOH), and lepidocrocite (γ-FeOOH).The spectral reflectivity measurements were made between 0.35 and 2.20 μm over the temperature interval between about −110° and 20°C.

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Chemical and mineral transformation of a low grade goethite

2014.6.1  There is significant magnetite (M) in the roasted sample (Image B on right), while a number of impurities and goethite are seen in the head sample (Image A on left). H: Hematite, M: Magnetite, VG: Vitreous Goethite, EG: Earthy Goethite, OG: Ochreous Goethite, K: Kaolinite, and QTZ: Quartz. Download : Download full-size image; Fig. 15.

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Arsenic adsorption onto hematite and goethite - ScienceDirect

2009.8.1  Sorption experiments of arsenic were conducted onto commercial hematite and goethite. The main physico-chemical properties (Table 1) relative to the reactivity of a mineral powder are: the grain size, the specific surface area, the acid–base surface acidity constants (pK a1 and pK a2) corresponding to the protonation and deprotonation of the

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Heated goethite and natural hematite: Can Raman

2007.11.20  The chemical species involved in the present investigation are goethite, hematite and magnetite, since there are some reports in the literature suggesting the formation of magnetite when goethite is heated at temperatures close to 300 °C [22].These compounds are easily differentiated by their Raman spectra (Fig. 1 and Table 1), what

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Beneficiation of acid mine drainage (AMD): A viable option

2020.3.15  For the synthesis of goethite, hematite, and magnetite, Fe(III) and Fe(II) were recovered via sequential precipitation in batch reactors. Lime was added to treated water to synthesize high-grade gypsum. Furthermore, reverse osmosis (RO) was employed to reclaim drinking water as per South African drinking water standards (SANS 241 ...

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Hematite Common Minerals - University of Minnesota

2024.7.10  Regardless of its setting, hematite is usually found with other iron-bearing minerals, especially magnetite, goethite and siderite. In Early Proterozoic (2.5 to 1.6 billion year ago) iron ore deposits, layers of hematite and other iron oxides alternate with bands of chert (microcrystalline quartz) to form distinctively layered deposits known as ...

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Thermal treatment of natural goethite: Thermal transformation and ...

2013.9.20  1. Introduction. Goethite, α-FeOOH, is widely distributed, occurs in rocks, soils and throughout the global ecosystem, and has the diaspore structure which is based on hexagonal close packing [1].Generally, goethite is an oxidation, decomposition, weathering and hydrolyzation product of pyrite, siderite, magnetite and Fe-containing silicates [1]. ...

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Control of Earth-like magnetic fields on the transformation

2016.7.26  Hematite and goethite are the two most abundant iron oxides in soils and sediments from many climatic zones; they are, however, generated in competition with each other 1,2,3.Therefore, the ratio ...

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Magnetism of Al‐substituted magnetite reduced

2016.6.7  For example, a fire can heat the topmost centimeters of soil to 800°C and cause a reducing soil-pore atmosphere, e.g., CO and CO 2 [Tunstall et al., 1976; Haliuc et al., 2016], which results in transformation

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Mechanical properties of magnetite (Fe3O4), hematite (α

2011.10.3  For example, iron forms a wide range of oxides, such as: magnetite, hematite, wüstite, goethite and maghemite, depending on the environmental conditions. In this work, we limited the mechanical study to three of the most common oxides: hematite (α-Fe 2 O 3), magnetite (Fe 3 O 4) and goethite (α-FeOOH) which can be found under

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Heterogeneous reaction of NO2 with hematite, goethite and magnetite ...

2020.3.1  The iron fractional solubility for unreacted hematite, magnetite and goethite were found to be approximately in the range of (1-10) × 10 −5. After heterogeneous reaction with 2.5 ± 0.1 ppmv NO 2 for 24 h, the increase in iron fractional solubilities was very small and in some cases even insignificant. To our ...

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The origin and stability of lunar goethite, hematite and magnetite

1972.12.1  Its minimum stability against hematite is 2 bars total pressure at 130°C and 10 −3 bars at 30°C for H 2 to H 2 O ratios compatible with the high temperature redox state of lunar materials. Thus the traces of magnetite, hematite and goethite in lunar materials may be the result of normal low-temperature processes indigenous to the Moon and ...

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Mechanical properties of magnetite (Fe3O4), hematite (α

2011.10.3  For example, iron forms a wide range of oxides, such as: magnetite, hematite, wüstite, goethite and maghemite, depending on the environmental conditions. In this work, we limited the mechanical study to three of the most common oxides: hematite (α-Fe 2 O 3), magnetite (Fe 3 O 4) and goethite (α-FeOOH) which can be found under

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Magnetic analysis of commercial hematite, magnetite, and

2017.12.19  Magnetite is a ferrimagnetic phase with high magnetization (∼92 Am 2 /kg) and low coercivity (10-40 mT) while hematite is a canted antiferromagnetic phase having a small magnetization (∼0.4 Am 2 /kg) and high coercivity (∼100-400 mT). 1,5–9 Since oxidation-reduction reactions often occur in iron oxides, mixtures of magnetite

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Contrasting behavior of hematite and goethite within

2006.10.17  Because maghemite and magnetite have a magnetization about two orders of magnitude higher than that of hematite and goethite, the conversion from a significant amount of hematite + goethite to maghemite or magnetite would result in a large corresponding increase of χ and χ fd. However, these proxies do not show anomalies at

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Transformation of magnetite to goethite under alkaline pH

2007.3.1  The exact phase into which Tc(IV) is incorporated is unclear, however, goethite is known to form during the oxidation of magnetite 73 and as discussed, the Tc−Fe distances are consistent with ...

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Arsenic (V) adsorption from aqueous solution onto goethite, hematite ...

2011.10.17  Highlights Hematite, goethite, zero-valent iron and magnetite were used to remove As(V). Hematite is a suitable adsorbent over wide ranges of pH and As(V) concentrations. Arsenate adsorption isotherms are well fitted with the Langmuir model. Adsorption capacity is related to the iron content of adsorbents. Arsenate desorption from

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