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Infrared Vibrations of Hematite Formed From Aqueous- and Dry-Thermal Incubation of Si-Containing Ferrihydrite
Ferrihydrite Hematite Infrared spectroscopy Morphology Silicon Thermal treatment
2012/1/4
Ferrihydrite samples having Si/Fe molar ratios ranging from 0 to 1 were synthesized by the reaction of Fe2(SO4)3 and Na2SiO3 with NaOH to an equilibrium pH of 8.2. Hematite formed by incubating the fe...
Effect of Cobalt on the Formation of Crystalline Iron Oxides from Ferrihydrite in Alkaline Media
Cobalt Crystal growth Ferrihydrite Goethite Spinel Transmission electron microscopy
2011/11/30
Abstract: At pH 12 Co-ferrihydrite transformed to either Co-goethite or Co-magnetite, the latter compound appearing at Co additions of > 18 mole %. Although Co was readily taken up by the magnetite st...
Influence of Structural and Adsorbed Si on the Transformation of Synthetic Ferrihydrite
Adsorption Crystal structure Ferrihydrite Infrared spectroscopy Silicon Synthesis X-ray powder diffraction
2012/1/5
The transformation of ferrihydrite to goethite and/or hematite, as influenced by the presence of co-precipitated Si, was investigated by infrared spectroscopy (IR), X-ray powder diffraction (XRD), and...
New Data and a Revised Structural Model for Ferrihydrite
Crystal structure Ferrihydrite Iron Magnetic susceptibility Surface area Synthesis Thermal analysis Transmission electron microscopy X-ray absorption edge spectra
2012/1/9
Synthetic 2-line and 6-line ferrihydrite samples prepared from ferric nitrate solutions have the bulk compositions Fe4(O,OH,H20)12 and Fe4.6(O,OH,H2O)12, respectively. The composition depends on cryst...
Effect of Silicate Species on the Transformation of Ferrihydrite into Goethite and Hematite in Alkaline Media
Ferrihydrite Goethite Hematite Morphology Silicate Transmission electron microscopy
2011/11/25
Abstract: The transformation of ferrihydrite to goethite and/or hematite in alkaline media is strongly retarded by the presence of silicate species. These species probably stabilize ferrihydrite by ad...
Effect of Manganese on the Transformation of Ferrihydrite into Goethite and Jacobsite in Alkaline Media
Ferrihydrite Goethite Jacobsite Manganese Phyllomanganate Synthesis Transmission electron microscopy
2011/11/25
Abstract: In the presence of Mn(II), ferrihydrite transforms into Mn-goethite and/or jacobsite. Chemical analysis showed that as much as 15 mole % Mn replaced Fe in the goethite structure. If Mn(III) ...
Effect of Solution Conditions on the Proportion and Morphology of Goethite Formed from Ferrihydrite
Ferrihydrite Goethite Hydroxyl Iron Morphology Transmission electron microscopy
2012/2/2
In alkaline media and at 70°C dilute suspensions of ferrihydrite transformed to goethite between pH 11.2 and 14 and to a mixture of goethite and hematite above and below this pH range. Increasing the ...
Effect of pH on the Formation of Goethite and Hematite from Ferrihydrite
Ferrihydrite Goethite Hematite Mossbauer spectroscopy pH X-ray powder diffraction
2012/2/7
Storage of ferrihydrite in aqueous suspensions at 24°C and pHs between 2.5 and 12 for as long as three years resulted in the formation of goethite and hematite. The proportions and crystallinity of th...
Influence of Relative Humidity on the Crystallization of Fe(III) Oxides From Ferrihydrite
Ferrihydrite Goethite Hematite Iron oxides Relative humidity Synthesis
2012/2/7
Ferrihydrite prepared in different manners was kept under relative humidities ranging from 75 to 100% and at temperatures of 45° and 55°C for 180 days. Ferrihydrite transformed to hematite and goethit...
Influence of Organic Anions on the Crystallization of Ferrihydrite
Crystallization Ferrihydrite Goethite Hematite Hydroxy-carboxylic acid
2012/2/10
Hydroxy-carboxylic acids inhibit the crystallization of ferrihydrite in the pH range 9–11 in the order citric > meso tartaric > L-tartaric ≫ lactic and favor hematite formation relative to goeth...