The rate of ferrihydrite transformation to goethite via the Fe(II) pathway

Yee, Nathan; Shaw, Samuel; Benning, Liane G.; Nguyen, Thu Hien

doi:10.2138/am.2006.1860

Cited by 165 publications

(138 citation statements)

References 17 publications

Supporting

Mentioning

122

Contrasting

Order By: Relevance

“…The induction times observed in this study are generally in accordance with the findings of Yee et al (6) at ambient temperature when 2-line ferrihydrite was reacted with concentrated 100mM Fe(II) solution. However, in their study, goethite was the only transformation product detected, in contrast to the observations from this study and those cited above.…”

Section: Reconciliation Of the Controversies In Previous Studiessupporting

confidence: 92%

“…There are also inconsistent reports on which transformation product formed in experiments conducted under similar conditions. Yee et al (6) reported a transformation product of goethite only for the reaction of 2-line ferrihydrite with 100 mM Fe(II), which is inconsistent with the results of magnetite formation at much lower Fe(II) concentrations in the studies of Hansel et al (4). Tronc et al (5) reported the topotactic transformation of freshly synthesized 2-line ferrihydrite to magnetite as a result of mixing with Fe(II) solution, while Hansel et al (4) attributed the transformation to magnetite mainly to nucleation and recrystallization.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Kinetics of Fe(II)-Catalyzed Transformation of 6-line Ferrihydrite under Anaerobic Flow Conditions

Yang

Steefel

Marcus

et al. 2010

Environ. Sci. Technol.

132

138

View full text Add to dashboard Cite

The readsorption of ferrous ions produced by the abiotic and microbially-mediated reductive dissolution of iron oxy-hydroxides drives a series of transformations of the host minerals. To further understand the mechanisms by which these transformations occur and their kinetics within a microporous flow environment, flow-through experiments were conducted in which capillary tubes packed with ferrihydrite-coated glass spheres were injected with inorganic Fe(II) solutions under circumneutral pH conditions at 25ºC. Synchrotron X-ray diffraction was used to identify the secondary phase(s) formed and to provide data for quantitative kinetic analysis. At concentrations at and above 1.8 mM Fe(II) in the injection solution, magnetite was the only secondary phase formed (no intermediates were detected), with complete transformation following a nonlinear rate law requiring 28 hours and 150 hours of reaction at 18 and 1.8 mM Fe(II), respectively. However, when the injection solution consisted of 0.36 mM Fe(II), goethite was the predominant reaction product and formed much more slowly according to a linear rate law, while only minor magnetite was formed. When the rates are normalized based on the time to react half of the ferrihydrite on a reduced time plot, it is apparent that the 1.8 mM and 18 mM input Fe(II) experiments can be described by the same reaction mechanism, while the 0.36 input Fe(II) experiment is distinct. The analysis of the transformation kinetics suggest that the transformations involved an electron transfer reaction between the aqueous as well as sorbed Fe(II) and ferrihydrite acting as a semiconductor, rather than a simple dissolution and recrystallization mechanism. A transformation mechanism involving sorbed inner sphere Fe(II) alone is not supported, since the essentially equal coverage of sorption sites in the 18 mM and 1.8 mM Fe(II) injections cannot explain the difference in the transformation rates observed.

show abstract

Section: Reconciliation Of the Controversies In Previous Studiessupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Kinetics of Fe(II)-Catalyzed Transformation of 6-line Ferrihydrite under Anaerobic Flow Conditions

Yang

Steefel

Marcus

et al. 2010

Environ. Sci. Technol.

132

138

View full text Add to dashboard Cite

show abstract

“…(II) The influence of temperature on the precipitation behavior was analyzed by conducting experiments at five temperatures (4,12,21,30,40 • C) for a 50 mmol·L −1 CaSO 4 solution. (III) Finally, the effect of additives on the precipitation of calcium sulphate was studied for 50, 75, 100 and 150 mmol·L −1 CaSO 4 solutions at 21 • C. One additive, Mg, which enhances the solubility of CaSO 4 , was introduced, replacing the Na + ions with Mg 2+ ions in stoichiometric conditions (MgSO 4 ·7H 2 O and CaCl 2 ·2H 2 O were used as reactants, and a 1:1 Ca 2+ /Mg 2+ ratio was maintained for all cases).…”

Section: Methodsmentioning

confidence: 99%

“…This model applies to specific solid-state phase transformations. However, it has also been used to fit other nucleation-and-growth processes exhibiting sigmoidal conversion kinetics, such as crystal formation from solution and melts [21,22]. For solid-state phase transformations, the value of n is usually related to the mechanism of nucleation and the dimensionality of growth.…”

Section: Saxs and Waxs Data Processingmentioning

confidence: 99%

See 1 more Smart Citation

Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum

et al. 2017

View full text Add to dashboard Cite

Synchrotron-based small-and wide-angle X-ray scattering (SAXS/WAXS) was used to examine in situ the precipitation of gypsum (CaSO 4 ·2H 2 O) from solution. We determined the role of (I) supersaturation, (II) temperature and (III) additives (Mg 2+ and citric acid) on the precipitation mechanism and rate of gypsum. Detailed analysis of the SAXS data showed that for all tested supersaturations and temperatures the same nucleation pathway was maintained, i.e., formation of primary particles that aggregate and transform/re-organize into gypsum. In the presence of Mg 2+ more primary particle are formed compared to the pure experiment, but the onset of their transformation/reorganization was slowed down. Citrate reduces the formation of primary particles resulting in a longer induction time of gypsum formation. Based on the WAXS data we determined that the precipitation rate of gypsum increased 5-fold from 4 to 40 • C, which results in an effective activation energy of~30 kJ·mol −1 . Mg 2+ reduces the precipitation rate of gypsum by more than half, most likely by blocking the attachment sites of the growth units, while citric acid only weakly hampers the growth of gypsum by lowering the effective supersaturation. In short, our results show that the nucleation mechanism is independent of the solution conditions and that Mg 2+ and citric acid influence differently the nucleation pathway and growth kinetics of gypsum. These insights are key for further improving our ability to control the crystallization process of calcium sulphate.

show abstract

Structural Effects of Solvents on the Breathing of Metal–Organic Frameworks: An In Situ Diffraction Study

et al. 2008

View full text Add to dashboard Cite

Raum zum Atmen: Zeitaufgelöste Beugungsstudien der Expansion und Kontraktion metall‐organischer Netzwerke in Gegenwart verschiedener Flüssigkeiten zeigen, dass ein schneller Austausch von Gastmolekülen stattfindet. In manchen Fällen ist der Austausch direkt (wie am Beispiel von Wasser gegen Pyridin gezeigt), in anderen Fällen treten kristalline Intermediate auf, die partiell expandierten Formen entsprechen.

show abstract

The rate of ferrihydrite transformation to goethite via the Fe(II) pathway

Cited by 165 publications

References 17 publications

Kinetics of Fe(II)-Catalyzed Transformation of 6-line Ferrihydrite under Anaerobic Flow Conditions

Kinetics of Fe(II)-Catalyzed Transformation of 6-line Ferrihydrite under Anaerobic Flow Conditions

Physicochemical and Additive Controls on the Multistep Precipitation Pathway of Gypsum

Structural Effects of Solvents on the Breathing of Metal–Organic Frameworks: An In Situ Diffraction Study

Contact Info

Product

Resources

About