Effect of Ce(IV) doping on formation of goethite and its transformation to hematite

Mohapatra, Mamata; Sahoo, Saroj Kumar; Mohanty, Chandi; Das, R.P.; Anand, S.

doi:10.1016/j.matchemphys.2005.05.024

Cited by 24 publications

(20 citation statements)

References 22 publications

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“…1(b)], which is consistent with reports of other authors. [17][18][19][20] Through investigation with high-resolution TEM (HRTEM), we observed that some nanowires appear to have an amorphous surface and a highly crystalline core. One of these nanowires is shown on Fig.…”

Section: A Morphology Studiesmentioning

confidence: 99%

“…Our results are in general agreement with the reports, claiming that synthetic goethite forms needlelike crystallites. [16][17][18][19] We investigated their magnetic properties by superconducting quantum interference device (SQUID) and electron paramagnetic resonance (EPR) measurements. A typical superparamagnetic resonance was detected in the entire temperature range between 375 and 4 K. Upon heating, changes in the EPR signal occurred at 375 K. We believe that this is due to the magnetic transition of goethite nanowires into a paramagnetic state.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, structure, and magnetic properties of iron-oxide nanowires

et al. 2006

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Iron-oxide nanowires were synthesized by a hydrothermal treatment of Fe(OH) 3 dispersion in NaOH. The obtained materials were first structurally investigated by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, and thermogravimetric analysis techniques. Their magnetic properties were then examined by superconducting quantum interference device and electron paramagnetic resonance methods. A typical nanowire measured 10-15 nm in diameter and 600 nm in length. All the structural and magnetic investigations were consistent with the nanowire goethite structure. The nanowire Neél transition temperature occurred at 375 K; i.e., it was lowered by 25 K with respect to the corresponding goethite bulk value. The shift in the ordering temperature was suggested to be a consequence of a growing importance of strains and surface effects at the nanoscale. We were also able to irreversibly convert goethite nanowires into hematite, by warming the sample to temperatures exceeding 530 K.

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Section: A Morphology Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis, structure, and magnetic properties of iron-oxide nanowires

et al. 2006

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“…11). Mohapatra et al (2005) also detected CeO2 at Fe:Ce molar ratios lower than 29:1. According to the authors, it initially precipitated as amorphous Ce(OH)4 from aqueous solution containing both Fe and Ce and then crystallised as CeO2.…”

Section: Mineralogical Characterization Of Precipitated Phasesmentioning

confidence: 87%

“…On the other hand, such effects were not observed in Ce doped goethite. Mohapatra et al (2005) also reported higher capability of goethite to incorporate Ce without significant changes in its structures. This is probably the reason why the increase in Ce concentration did not lead to precipitation of lepidocrocite, differently of other REE in this study.…”

Section: Mineralogical Characterization Of Precipitated Phasesmentioning

confidence: 91%

“…It is unlike that REE isomorphically replace Fe 3+ , given the difference between the ionic radii of these elements, but it could still be considered depending on the Fe (hydr)oxide structure. In fact, there are reports for isomorphic substitution of Fe or Fe-O groups by Ce on Fe (hydr)oxides (Mohapatra et al 2005). Moreover, the possibility of adsorption and/or coprecipitation of these elements with Fe-oxides is a possibility that remains to be studied.…”

Section: Introductionmentioning

confidence: 99%

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Removal of lanthanum, cerium, europium and holmium from water by co-precipitation with iron and aluminium (hydr)oxides

Barcelos¹

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Effluents from mining activities may have high concentrations of trace elements such as arsenic, rare earth elements (REE) and actinides, mainly in areas where acid mine drainage (AMD) occurs. Use of lime to neutralise AMD also promote co-precipitation of iron (Fe) and aluminium (Al) (hydr)oxides, increasing the removal of trace elements from water. This study aimed to evaluate the efficiency of Fe/Al (hydr)oxides co-precipitation to remove lanthanum (La), cerium (Ce), europium (Eu) and holmium (Ho) from water under laboratory conditions. Two sets of experiments were performed with individual REE solutions containing Eu and Ho. In these cases, Fe(II) and Al sulphates were used at different Fe:Al:REE molar ratios. Two other sets of experiments with Fe(II) and Fe(III) sulphates were performed in a mixed REE solution containing La, Ce, Eu and Ho. To coprecipitate Fe/Al (hydr)oxides, pH's were raised to 9.0 and 6.0 with 5 mol L-1 KOH solution. Soluble contents of Fe, Al and REE were periodically measured in supernatants aliquots. Precipitates were collected at the end of the 60-day incubation period and, then, oven-dried, sieved and characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The stability of REE in precipitates was also assessed by BCR sequential extractions. All treatments presented high REE removal efficiency from water at pH 9.0, but significantly lower at pH 6.0 for Fe(II) treatments. Magnetite precipitation was favoured by lower contents of REE and Al, whereas goethite and lepidocrocite were favoured at higher contents. Segregated phases were not detected for Eu and Ho, but lanthanite and cerianite precipitated at high amounts of La and Ce, respectively. For mixed REE treatments, the mineralogical phases precipitated were mostly poorly crystallised. The presence of magnetite was associated to higher REE stabilities, whereas lepidocrocite decreased the stability as measured by BCR extractions. The presence of segregated phases as cerianite resulted in increased Ce stability, but presence of lanthanite decreased La stability in precipitates.

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⁵⁷Fe Mössbauer Spectroscopy In The Investigation of The Precipitation of Iron Oxides

Musić¹,

Ristić²,

Krehula³

2013

Mössbauer Spectroscopy

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Effect of Ce(IV) doping on formation of goethite and its transformation to hematite

Cited by 24 publications

References 22 publications

Synthesis, structure, and magnetic properties of iron-oxide nanowires

Synthesis, structure, and magnetic properties of iron-oxide nanowires

Removal of lanthanum, cerium, europium and holmium from water by co-precipitation with iron and aluminium (hydr)oxides

⁵⁷Fe Mössbauer Spectroscopy In The Investigation of The Precipitation of Iron Oxides

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Effect of Ce(IV) doping on formation of goethite and its transformation to hematite

Cited by 24 publications

References 22 publications

Synthesis, structure, and magnetic properties of iron-oxide nanowires

Synthesis, structure, and magnetic properties of iron-oxide nanowires

Removal of lanthanum, cerium, europium and holmium from water by co-precipitation with iron and aluminium (hydr)oxides

57Fe Mössbauer Spectroscopy In The Investigation of The Precipitation of Iron Oxides

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⁵⁷Fe Mössbauer Spectroscopy In The Investigation of The Precipitation of Iron Oxides