Arsenic (V) adsorption from aqueous solution onto goethite, hematite, magnetite and zero-valent iron: Effects of pH, concentration and reversibility 2011 • Charlotte Hurel

The objectives of this study were to (1) characterize synthetic and natural iron oxides (hematite, magnetite), hydroxides (ferrihydrite, goethite, lepidocrocite, akaganéite), a carbonate (siderite), a sulfate (Na-jarosite), and ferric arsenates (scorodite, yukonite) using Raman spectroscopy; (2) record and analyze the spectral patterns of ...

610‡C. Goethite and hematite were the magnetically dominant phases after all runs except 500‡C and 610‡C, for which only hematite was found. However, partially dehydrated goethites after the 238^402‡C runs had broad peaks or ... Magnetite and hematite have distinctive rema-nence transitions: magnetite at TV =110^125 K (the Verwey ...

Like magnetite, hematite is an oxide of iron and it has the formula Fe 2 O 3. Hematite is not magnetic, and so is not readily removed from soils to which it has been added. ... Interestingly, when the hematite is hydrated to either goethite or ferrihydrite, adsorption favours phosphate, whilst unhydrated hematite favours the herbicide. It ...

Magnetite is a redox active Fe oxide common in most soil and sedimentary environments. In this study, we investigated magnetite transformations under extreme alkaline conditions (0.1–2 mol l –1 NaOH) similar to those found under high-level radioactive waste storage tanks at the Hanford site in the State of Washington, USA. X-ray diffraction ...

The transformation of weakly magnetic hematite to magnetite is a promising technique that can enhance the efficiency of magnetic separation of hematite quartzite. The transformation of hematite into magnetite involves the partial reduction of Fe(III) to Fe(II) and converting the rhombohedral crystal system of hematite into cubic of magnetite.

The samples were composed of hematite, magnetite and goethite with a great variety of microstructural features. The following fea-tures were identified: martitic hematite with marked microporosity resulting from the martitization process; lamellar hematite; botryoidal goethite; microporous goethite; earthy-like goethite; and magnetite in differ-

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 …

Hematite-Goethite: from Norristown, Montgomery County, Pennsylvania Hemimorphite var. Calamine: from Friedensville, Lehigh County, ... Magnetite (dodecahedral crystals) from Jones Mine (Jones Good Luck Mine ), Hopewell Furnace District, Caernarvon Township, Berks County, Pennsylvania

The magnetite, hematite and goethite capping all can be effective for the suppression of endogenous P release from sediment into OW under anoxic conditions, …

Abstract Iron ore, pellets, and sinter were reduced with hydrogen at 800 °C to understand the degree of reduction and the mineralogical aspects. The weight loss of goethite and limonite iron ore was noticed to be lower than that of magnetite and hematite varieties. X-ray diffractometry (XRD) indicated 100 pct Fe in the case of hematite, 93 pct …

The hematite is red to black, oolitic to massive, earthy to hard. It was associated with goethite and an array of phosphate minerals (Chamberlain, 1877, Hawley and Beavens, 1934; U.S.G.S., 1976; Paull, 1977). It was mined along Iron Ridge near Mayville in Sec. 12 and 13 T.11N R.16E until the mid-1970's. Beds up to 55 feet thick occurred.

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 ...

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 …

[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 present FORC diagrams for predominantly single-domain (SD) synthetic aluminous hematite (α-Fe 2-x Al x O 3) and goethite (α-(FeAl)OOH) and …

Compared with hematite and magnetite, goethite has a much more diverse range of textural forms and occurrences, and its influence on iron ore processing is less understood. Currently, most analysis of the effects of goethite on mine performance considers only the chemistry of the ore and not its textural components. Through improved textural ...

The iron formation-hosted iron ores are subdivided into unenriched iron formation ores, martite-goethite supergene ores, residual hematite ores and microplaty hematite ores. The three most common iron ore minerals are magnetite (Fe 3 O 4 ), hematite (Fe 2 O 3 ) and goethite (FeOOH), with the most common forms of goethite being brown, yellow ...

Elemental mappings of Fe-hydroxide, goethite, hematite, magnetite, and gypsum were obtained using the HR-SEM-EDS Results are shown in Fig. 3 (A–E). Specifically, as shown in Fig. 3 (A–C), granular like structures were observed on the surface of recovered material. This is a clear indication that calcination did not affected the …

The present study was undertaken with the aim of preparing magnetite and goethite of pigment particle size < 10 μm via water-soluble mill scale-derived precursors. Furthermore, maghemite and hematite could then be prepared by thermal treatment of the obtained magnetite and goethite, respectively.2. Experimental2.1. Chemical …

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

Raman peaks identified in the range of 100–1250 cm −1 are collected in Table 2 for complex and pure oxides together with the peak values related to hematite, magnetite and goethite mentioned by de Faria and Lopes [16]. It is noticeable that the values of the Raman peaks observed on the complex and on the pure oxides are very similar and ...

The transformation of goethite and hematite to magnetite was monitored by measuring the hysteresis properties of each sample after heating. Distinct …

Magnetite displays an unusual lamellar and/or acicular habit underlined by dusty Si-bearing inclusions, less than 1 μm in size, typical of the variety termed "silician magnetite" ().In detail, the inner parts of such magnetite lamellae become inclusion-free prior to pseudomorphic replacement by hematite ().The resulting hematite is a …

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 …

Spectral and other physicochemical properties were determined for a suite of submicron powders of hematite (alpha-Fe2O3), maghemite (gamma-Fe2O3), magnetite (Fe3O4), goethite (alpha-FeOOH), and lepidocrocite (gamma-FeOOH). The spectral reflectivity measurements were made between 0.35 and 2.20 microg …

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 …

A commercial hematite (BDH Chemicals) with 95% purity was also considered as a reference sample. Differential thermal analysis (DTA) and …