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Title: Nano size crystals of goethite, {alpha}-FeOOH: Synthesis and thermal transformation

Abstract

An aqueous suspension of amorphous iron(III) hydroxide was kept at room temperature (298 K) for 23 years. During this period of time the pH of the liquid phase changed from 4.3 to 2.85, and nano size crystals of goethite, {alpha}-FeOOH crystallised from the amorphous iron(III) hydroxide. Transmission electron microscopy (TEM) investigations, Moessbauer spectra, and powder X-ray diffraction using Co K{alpha} radiation showed that the only iron containing crystalline phase present in the recovered product was {alpha}-FeOOH. The size of these nano particles range from 10 to 100 nm measured by TEM. The thermal decomposition of {alpha}-FeOOH was investigated by time-resolved in situ synchrotron radiation powder X-ray diffraction and the data showed that the sample of {alpha}-FeOOH transformed to {alpha}-Fe{sub 2}O{sub 3} in the temperature range 444-584 K. A quantitative phase analysis shows the increase in scattered X-ray intensity from {alpha}-Fe{sub 2}O{sub 3} to follow the decrease of intensity from {alpha}-FeOOH in agreement with the topotactic phase transition. - Graphical abstract: Nano size crystals of goethite, {alpha}-FeOOH formed from amorphous iron(III) hydroxide after 23 years, and transforms faster to {alpha}-Fe{sub 2}O{sub 3} upon heating.

Authors:
 [1];  [2];  [3];  [4]
  1. Crystal Chemistry, Hojkolvej 7, DK-8210 Arhus V (Denmark)
  2. Interdisciplinary Nanoscience Centre (iNANO), Department of Chemistry, University of Aarhus, DK-8000 Arhus C (Denmark), E-mail: trj@chem.au.dk
  3. Materials Research Department, Riso National Laboratory, P.O. Box 49, DK-4000 Roskilde (Denmark)
  4. National Synchrotron Light Source Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)
Publication Date:
OSTI Identifier:
21015793
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 4; Other Information: DOI: 10.1016/j.jssc.2007.01.032; PII: S0022-4596(07)00064-3; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; GOETHITE; IRON HYDROXIDES; IRON OXIDES; MOESSBAUER EFFECT; PHASE STUDIES; PHASE TRANSFORMATIONS; SYNCHROTRON RADIATION; SYNTHESIS; TEMPERATURE RANGE 0273-0400 K; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION

Citation Formats

Christensen, Axel Norlund, Jensen, Torben R., Bahl, Christian R.H., and DiMasi, Elaine. Nano size crystals of goethite, {alpha}-FeOOH: Synthesis and thermal transformation. United States: N. p., 2007. Web. doi:10.1016/j.jssc.2007.01.032.
Christensen, Axel Norlund, Jensen, Torben R., Bahl, Christian R.H., & DiMasi, Elaine. Nano size crystals of goethite, {alpha}-FeOOH: Synthesis and thermal transformation. United States. doi:10.1016/j.jssc.2007.01.032.
Christensen, Axel Norlund, Jensen, Torben R., Bahl, Christian R.H., and DiMasi, Elaine. Sun . "Nano size crystals of goethite, {alpha}-FeOOH: Synthesis and thermal transformation". United States. doi:10.1016/j.jssc.2007.01.032.
@article{osti_21015793,
title = {Nano size crystals of goethite, {alpha}-FeOOH: Synthesis and thermal transformation},
author = {Christensen, Axel Norlund and Jensen, Torben R. and Bahl, Christian R.H. and DiMasi, Elaine},
abstractNote = {An aqueous suspension of amorphous iron(III) hydroxide was kept at room temperature (298 K) for 23 years. During this period of time the pH of the liquid phase changed from 4.3 to 2.85, and nano size crystals of goethite, {alpha}-FeOOH crystallised from the amorphous iron(III) hydroxide. Transmission electron microscopy (TEM) investigations, Moessbauer spectra, and powder X-ray diffraction using Co K{alpha} radiation showed that the only iron containing crystalline phase present in the recovered product was {alpha}-FeOOH. The size of these nano particles range from 10 to 100 nm measured by TEM. The thermal decomposition of {alpha}-FeOOH was investigated by time-resolved in situ synchrotron radiation powder X-ray diffraction and the data showed that the sample of {alpha}-FeOOH transformed to {alpha}-Fe{sub 2}O{sub 3} in the temperature range 444-584 K. A quantitative phase analysis shows the increase in scattered X-ray intensity from {alpha}-Fe{sub 2}O{sub 3} to follow the decrease of intensity from {alpha}-FeOOH in agreement with the topotactic phase transition. - Graphical abstract: Nano size crystals of goethite, {alpha}-FeOOH formed from amorphous iron(III) hydroxide after 23 years, and transforms faster to {alpha}-Fe{sub 2}O{sub 3} upon heating.},
doi = {10.1016/j.jssc.2007.01.032},
journal = {Journal of Solid State Chemistry},
number = 4,
volume = 180,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • An aqueous suspension of amorphous iron(III) hydroxide was kept at room temperature (298 K) for 23 years. During this period of time the pH of the liquid phase changed from 4.3 to 2.85, and nano size crystals of goethite, {alpha}-FeOOH crystallized from the amorphous iron(III) hydroxide. Transmission electron microscopy (TEM) investigations, Moessbauer spectra, and powder X-ray diffraction using Co K{alpha} radiation showed that the only iron containing crystalline phase present in the recovered product was {alpha}-FeOOH. The size of these nano particles range from 10 to 100 nm measured by TEM. The thermal decomposition of {alpha}-FeOOH was investigated by time-resolvedmore » in situ synchrotron radiation powder X-ray diffraction and the data showed that the sample of {alpha}-FeOOH transformed to {alpha}-Fe{sub 2}O{sub 3} in the temperature range 444--584 K. A quantitative phase analysis shows the increase in scattered X-ray intensity from {alpha}-Fe{sub 2}O{sub 3} to follow the decrease of intensity from {alpha}-FeOOH in agreement with the topotactic phase transition.« less
  • The complexation of Pb(II) on a hydrous goethite surface has been investigated. Equilibrium measurements have been performed as potentiometric titrations at 298.2 K, within the range 2.7 < -log [H[sup +]] < 8.5. Three different ionic media were used: 0.1 mol dm[sup [minus]3] NaNO[sub 3], 0.1 mol dm[sup [minus]3] NaCl, and a mixture (1:1) of both these media. The evaluation of experimental data was made, using the constant capacitance model, within which a previously determined model for the acid-base reactions was included. The formation of the following complexes within the system H[sup +] - [triple bond]FeOH - Pb[sup 2+], wasmore » found to describe the surface complexation: [triple bond]FeOHPb[sup 2+] (log [beta][sub 0,1,1,0][sup s](int) = 8.20 [+-] 0.06); [triple bond]FeOPb[sup +] (log [beta][sub -1,1,1,0][sup s](int) = 0.17 [+-] 0.04); [triple bond]FeOPbOH (log [beta][sub -2,1,1,0][sup s](int) = -8.85 [+-] 0.08). Within the four component system H[sup +] - [triple bond]FeOH - Pb[sup 2+] - Cl[sup [minus]], the following complexes were added to the model: [triple bond]FeOHPbCl[sup +] (log [beta][sub 0,1,1,1][sup s](int) = 7.50 [+-] 0.08); [triple bond]FeOPbCl (log [beta][sub -1,1,1,1][sup 2](int) = -0.35 [+-] 0.16); [triple bond]FeOPbOHCl[sup [minus]] (log [beta][sub -2,1,1,1][sup s](int) = -8.00 [+-] 0.12). In the presence of an excess of Pb(II) ions to surface binding sites, the formation of a polynuclear surface Pb(II) species is postulated. The proposed model has been verified by independent determination of total soluble Pb(II) concentrations. Model calculations, using concentrations typical for natural waters, demonstrate a strong adsorption of Pb(II) even at low concentrations of surface binding sites. The experimental data show fully reversible reactions.« less
  • Surface complexation of inorganic mercury(II) and monomethyl (CH[sub 3]Hg[sup +]) onto a hydrous goethite ([alpha]-FeOOH) surface has been studied. The pH ([minus]log[H[sup +]]) has been varied within the range 2.7 < [minus]log[H[sup +]] < 9, at 298 K, using a 0.1 mol dm[sup 3] NaNO[sub 3] medium. Low total mercury concentrations ([approx] 1 mmol/dm[sup 3]) were used. Inorganic mercury and methyl mercury content in the water phase, in the goethite phase, and adsorbed on the vessel walls was determined by GFAAS and GC-coupled MIP-AES. The inorganic mercury distribution was evaluated, using a previously determined surface complexation model, based on themore » constant capacitance concept. This model was derived using about 10[sup 3] times higher total mercury concentrations. In the presence of goethite, approximately 80% of both methyl mercury and inorganic mercury(II) was recovered in the different phases. The extractable fraction adsorbed to the vessel walls was found to be low. About 20% of the inorganic mercury added remained soluble in the presence of goethite. This is close to the predicted value, using a previously determined model derived in the mmol/dm[sup 3] range. This implies that the concept of specific high affinity sites is questionable in the case of near trace concentrations of Hg(II). Methyl mercury was found to be weakly coordinated, with about 15% adsorbed on the goethite surface. Furthermore, a model calculation describing the surface complexation of methyl mercury on goethite was performed. The experimental data could best be explained by the formation of the surface complexes [triple bond]FeOHHgCH[sub 3][sup +] and [triple bond]FeOHgCH[sub 3].« less
  • This work is concerned with the adsorption of o-phthalate (1,2-benzenedicarboxylate) at the water-metal (hydr)oxide interface. Previously published infrared spectroscopic, potentiometric, and adsorption data characterizing the boehmite ({gamma}-AlOOH) system are compared with new data collected for o-phthalate adsorption on aged {gamma}-Al{sub 2}O{sub 3} and goethite ({alpha}-FeOOH). The study focuses on identifying bonding mechanisms, stoichiometries, and stabilities of the formed complexes, and comparing these among the three systems. Furthermore, the effects of ionic strength and composition of the ionic medium are investigated. The infrared spectroscopic data provided direct, molecular-level evidence for the existence of two dominating surface complexes on all three solids.more » One was shown to be a deprotonated outer-sphere species and the other was n inner-sphere surface complex. The inner-sphere complexes on the three solids were structurally related, and they were tentatively assigned to a mononuclear, chelating structure involving both carboxylate groups. The outer-spheres complexes were shown to increase in relative importance at high pH and low ionic strengths, while low pH and high ionic strengths favored the inner-sphere complexes. The information gained from the infrared spectroscopic investigations was used as qualitative input in the formulation of the surface complexation models. New models, based on the extended constant capacitance approach, were presented for the o-phthalate/aged {gamma}-Al{sub 2}O{sub 3} and o-phthalate/goethite systems.« less