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The Fe II-III oxyhydroxycarbonate fougerite mineral and green rusts in hydromorphic soils J.-M. R. Génin et al. Institut Jean Barriol Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS- Université Henri Poincaré-Nancy 1, - PowerPoint PPT Presentation
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“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
The FeII-III oxyhydroxycarbonate fougerite mineral and green rusts in
hydromorphic soils
J.-M. R. Génin et al.
Institut Jean BarriolLaboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS-
Université Henri Poincaré-Nancy 1,Département Matériaux et Structures, ESSTIN,
405 rue de Vandoeuvre, F-54600 Villers-lès-Nancy, France. E-Mail:[email protected]
Green rusts and fougerite in the biogeochemical cycle of iron, A. Herbillon and J.-M. R. Génin Editors, C. R. Geoscience, 338 (2006) 393-498.
“Gütlich, Bill, Trautwein: M össbauer Spectroscopy and Transition Metal Chemistry@�� Springer-Verlag 2009”
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
The morphology of hydromorphic gley soils, first described in 1905 by G. N. Vysostskii1, remained a mystery up till recently when Mössbauer spectroscopy has been the determining tool to identify the iron containing compound that lies in a horizon formed under waterlogged conditions in an anaerobic environment, which encourages the reduction of iron compounds by microorganisms and often causes mottling of soil into a patchwork of greenish-blue-grey and rust colors. This finding is of utmost practical importance since there exists a correlation between the concentration of some pollutants and that of FeII ions that are dissolved in the water table. For instance, nitrates disappear where FeII appear in the anaerobic zone by following the water level in equilibrium with a mineral, which has been given the name of fougerite (IMA 2003-05). It occurs to be the FeII-III oxyhydroxycarbonate of formula FeII
6(1-x) FeIII6x O12 H2(7-3x) CO3
where the domain of x is limited to [0.33-0.67]. Originally studied for explaining the corrosion of iron-based materials, FeII-III hydroxysalts belong to the family of layered
double hydroxides (LDH) and are constituted of layers, [FeII(1-x) FeIII
x (OH)2 ] x+, and interlayers, [(x/n)An-(mx/n)H2O]x-. Here, we shall consider only the case where the anion is CO3
2-.
• 1G. N. Vysostskii, Gley, Pochvovedeniye, 4 (1905) 291-327.
fougerite
Ferric oxyhydroxides
Organic matterHumus
Hydromorphic gley soil profileValley of the Vraine river, 10 km north of Vittel
(France)
0
2
3
4
0 2 4 6
Exchangeable Mn (mg kg-1)
0
1
2
3
4
0 10
20
CaCO3 (wt-%)
0
1
2
3
4
0 1 2
Nitrate-N (mg kg-1)
0
1
2
3
4
0 10
20
Exchangeable Fe
0
1
2
3
4
20
40
60
Fe(II) of total Fe (%)
0
1
2
3
4
0 0,2
0,4
Total Organic Carbon (wt-%)
Depth (m)
Vibeke Ernstsen, Geological Survey of Denmark and Greenland
(mg kg-1)
Depth profile analysis of a gleysol in Denmark through the redox zone between 2 and 3 meters deep. From left to right: Concentration of total organic carbon, calcium carbonate, nitrate, exchangeable iron, {[FeII] / [Fetotal]} and exchangeable Mn. Nitrates disappear when FeII appears.
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
The FeII-III hydroxycarbonate can be prepared by coprecipitation of a mixture of ferrous and ferric salts in the presence of carbonate ions when adding NaOH solution. Mössbauer spectra measured at 78 K demonstrate that the range of composition for x = [FeIII]/[Fetotal] is limited to [1/4, 1/3] since for x > 1/3 there exists two phases , the Green rust at x = 1/3, GR(CO3
2-), and another phase, -FeOOH.The spectrum of GR(CO3
2-) consists of 2 ferrous doublets D1 and D2 with large quadrupole splitting and one ferric doublet D3 with small splitting.
D3
D1
D2
78 K
-4 -3 -2 -1 0 1 2 3 4Velocity (mm s-1)
94
95
96
97
98
99100
Transmittance %
(b)
x = 0.33D1 D3
D2
Velocity (mm s-1)-4 -3 -2 -1 0 1 2 3 4
82
87
92
97
Transmittance %
x = 0.25
78 K (a)
D’1
D3
S2
S1
(c)78 K
x = 0.4
-12 -8 -4 0 4 8 12Velocity (mm s-1)
89
87
91
93
95
9799101
Transmittance %
D’1
D3
S2
S1
(d)78 K
x = 0.5
-12 -8 -4 0 4 8 12Velocity (mm s-1)
91
93
95
97
99
101
Transmittance %
FeII-FeIII ions coprecipitation giving for x > 1/3 a mixture of phases: GR(CO3
2-) and goethite
x 0.25 D1 D2 D3
1.28 1.28 0.47 2.97 2.55 0.43RA 62 12 26
x 0.33 D1 D2 D3
1.28 1.28 0.47 2.97 2.55 0.43RA 48 18 34
x 0.4 D1+D2 D3 S1 S2
H 490 482 1.30 0.50 0.43 0.54 2.9 0.47 0 0RA 52 25 17 6
x 0.5 D1+D2 D3 S1 S2
H 473 453 1.29 0.49 0.39 0.53 2.87 0.48 0 0RA 39 19 26 16Hyperfine parametersH (kOe), and (mm s-1), RA(%)FeII
(1-y)FeIIIy(OH)2 (y/2)CO3 with 1/4< y < 1/3
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
x = 0.33
Structure of GR(CO32-) FeII-III hydroxycarbonate at x = (1/3); (a) Three-dimensional view of the stacking of brucite-
like layers. OH- ions lie at the apices of the octahedrons surrounding the Fe cations. CO32- ions in interlayers.
(b) Projections along the c axis of the CO32- anions for three interlayers constituting a repeat.
Génin, J.-M. R.; Aissa, R.; Géhin, A.; Abdelmoula, M.; Benali, O.; Ernstsen, V.; Ona-Nguema, G.; Upadhyay, C.; Ruby, C. Fougerite and Fe II-III hydroxicarbonate green rust; ordering, deprotonation and/or cation substitution; structure of hydrotalcite-like compounds and mythic ferrosic hydroxide Fe(OH)(2+x). Solid State Sci., 7 (2005) 545-
572.
With synchrotronGR(CO3
2-) R(-3)m a = 0.317588(2) nm c = 2.27123(3) nm
R. Aissa, M. Francois, C. Ruby, F. Fauth, G. Medjahdi, M. Abdelmoula, J.-M. Génin, Formation and crystallographical structure of hydroxysulphate and hydroxycarbonate green rusts synthetised by coprecipitation • J. Phys. Chem. Solids, 67 (2006) 1016-1019.
(a) (b)
FeII4 FeIII
2 (OH)12 CO3
XRD and Mössbauer spectroscopy allowed us to determine the structure of all FeII-III hydroxysalts green rusts.
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
H2O2
Quadrupole splitting (mm s-1)
x = 1
84
88
92
96
100
x = 1
78 K(e)
94
96
98
100
Transmittance %
Velocity (mm s-1)-4 0 4-2 2-4 -3 -2 -1 0 1 2 3 4
Velocity (mm s-1)
x ~ 0.78
78 K (d)
Transmittance %
D3D1
D2
78 K
-4 -3 -2 -1 0 1 2 3 4Velocity (mm s-1)
99
94
95
96
97
98
100
Transmittance %
(a)
x = 0.33
Quadrupole splitting (mm s-1)
x ~ 0.50
D3
33 %D4
16.5 %78 K
Probability density (p) (b)
-1 0 1 2 3
D1
38 %
D2
12.5 %
x = 0.33 D3
33 %
78 K
Probability density (p)
(a)
-1 0 1 2 3
D1
50 %
D2
17 %
Quadrupole splitting (mm s-1)
84
88
92
96
100
Transmittance %
(b)
x ~ 0.50
78 K
-4 -3 -2 -1 0 1 2 3 4Velocity (mm s-1)
Quadrupole splitting (mm s-1)
D3
32 %
D4
31 %
78 K
Probability density (p)
(c)
-1 0 1 2 3
D1
28 %
D2
9 %
x ~ 0.63
(c)
x ~ 0.63
84
88
92
96
100
Transmittance %
78 K
-4 -3 -2 -1 0 1 2 3 4Velocity (mm s-1)
0.2 0.4 0.6 0.8 1.0 1.2 1.4
-0.2
-0.1
0.0
0.1
0.2
0.3
Eh(V)
{2 × [n(H2O2) / n(Fetotal)] + (1/3)}
Quadrupole splitting (mm s-1)
D3
35 %
D4
43 %
78 K
Probability density (p) (d)
-1 0 1 2 3
D1 + D2
22 %
x ~ 0.78
D3
33 %
D4
67 %
78 K
(e)
-1 0 1 2 3
Probability density (p)
with H2O2
a
bc
de
FeII6(1-x) FeIII
6x O12 H2(7-3x) CO3
The in situ oxidation of green rusts by deprotonationUse a strong oxidant such as H2O2, Dry the green rust and oxide in the air,
Violent air oxidation, Oxide in a basic medium…
FeII-III oxyhydroxycarbonate0 < x < 1
“Gütlich, Bill, Trautwein: M össbauer Spectroscopy and Transition Metal Chemistry@�� Springer-Verlag 2009”
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
003
0.2 µm
(a)GR(CO3
2-)
x = 0.33
0.2 µm
(b)H2O2
x = 0.50(c)
0.5 µm
H2O2
x = 1
(d)
0.5 µm
Aerialx = 1
10 20 30 40
Intensity (arb. unit)
Diffraction Angle (2
(c)
113
110018
012
015006
(a) (b)
(d)
10 20 30 40
Intensity (arb. unit)
Diffraction Angle (2TEM and XRD patterns of the FeII-III oxyhydroxycarbonate due to the in situ deprotonation
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
GR(CO32-)§
Ferrous GR
xFe(III) = {nFe(III) / (nFe(II) + nFe(III))}
A: FeII6 O12 H14 CO3
B: FeII4 FeIII
2 (OH)12 CO3
C: FeII2 FeIII
4 O12 H10 CO3
D: FeIII6 O12 H8 CO3
AD: FeII6(1-x) FeIII
6x O12H2(7-3x) CO3
G: Fe(OH)2
H: Fe3 O4
E: Ferroxyhite ’ FeOOH
Fe(OH)2
GR(CO32-)
Stoichiometric
Fe(II) Fe(III)
R =
{n
OH- /
(nF
e(II)
+ n
Fe(
III))}
Fe3 O4
Ferroxyhite ’ FeOOH
0 0.2 0.4 0.6 0.8 1
0
0.5
1
1.5
2.5
3
2
GR(CO32-)*
Ferric GRB
E
D
0.33 0.67
1.67
G
Pro- & deprotonation ofGR(CO3
2-)
A
Mass balance diagram of iron compounds
FeII4FeIII
2(OH)12CO3 + O2
FeIII6O12H8CO3 + 2 H2O
The oxidation or reduction of GR(CO32-) gives rise to GR(CO3
2-)* or GR(CO32-)§,
i.e. FeII6(1-x) FeIII
6x O12 H2(7-3x) CO3 where x [0, 1]; the fougerite mineral is limited to the range [1/3, 2/3].
fougerite
Voltammograms obtained on an iron disc at 10 mVs−1 in 0.4 M NaHCO3 solution at 25 °C and pH = 9.6.
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
20 µm
(e)
(A. Zegeye)
(G. Ona-Nguema)
(a) (b)
5 µm
(d)
(a) Production of Fe(II) and consumption of methanoate during culture of Shewanella putrefaciens in presence of lepidocrocite FeOOH. The initial amount of FeIII (as lepidocrocite ) and of methanoate were respectively 80 mM and 43 Mm.
(b) X-ray pattern of the solid phase of incubation experiments with S. putrefaciens: mixture of green rust (GR1) and siderite (S) obtained after 15 days of incubation.
(c) Mössbauer spectrum after 6 days of bioreduction.
(c) TEM observations and(d) optical micrograph of GR
crystals obtained by reduction of lepidocrocite by S. putrefaciens; One sees the bacteria that respirate GR*.
0
3
6
9
12
10 20 30 40 50 60
Intensity (a.u.)
2
GR1 (012)
GR1 (015)
GR1 (018)
GR1 (003)
GR1 (006)
S (104)
S (018)
Time (days)
0
10
20
30
40
50
60
70
0 6 12 18 24 30 36
Fe(II)Methanoate Abiotic control Methanoate (mM)
Fe(II) (mM)
80
GR* is also obtained by bacterial reduction of ferric oxyhydroxide
x ~ 0.50
(c)
Six days
Velocity (mm s-1)
Transmittance (%)
-4 -2 0 2 4
92
94
96
98
100D2
D
D’3D1
78 K
bioreduction
G. Ona-Nguema, M. Abdelmoula, F. Jorand, O. Benali, A. Géhin, J.-C. Block and J.-M. R. Génin, Iron (II,III) hydroxycarbonate green rust formation and stabilization from lepidocrocite bioreduction, Environ. Sci. and Technol. 36 (2002) 16-20
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
(d) The fougerite mineral is able to reduce pollutants within the water table such as nitrates. Dissimilatory iron reducing bacteria regenerate the fougerite active mineral4.
(a)
x ~ 0.50
-4 -2 0 2 4
Fougères
D3
D1
98.0
98.5
99.0
99.5
100.0
Transmittance %
78 K
Velocity (mm s-1)
Transmittance %
(b)
x = 0.5078 K
-4 -3 -2 -1 0 1 2 3 4Velocity (mm s-1)
synthetic
293 K
Fougères
(c)D1
D2
D3
-4 -3 -2 -1 0 1 2 3 4Velocity (mm s-1)
fougerite
NO3-
N2,NH4
+
+CO3
2-
CH2OCH2O
(d) 1, 2 4, 5 3
FeIII
FeII
+CO3
2-
Fougerite : FeII6(1-x)FeIII
6xO12H2(7-3x)CO3
Comparison between field experiments and laboratory assays
The similarity between the original spectrum obtained in 19961 (a) and that of the deprotonated oxyhydroxycarbonate2 (b) is striking. More recently, field experiments were done in Fougères using back-scattering miniaturized Mössbauer spectrometer MIMOS3 (c) to follow the value of ratio x with time and depth in situ within the gley soil.
1. J.-M. R Génin., G. Bourrié, F. Trolard, M. Abdelmoula, A. Jaffrezic, Ph. Refait, V. Maître, B. Humbert and A. Herbillon, Thermodynamic equilibria in aqueous suspensions of synthetic and natural Fe(II) - Fe(III) green rusts; occurences of the mineral in hydromorphic soils, Environ. Sci. Technol. 32 (1998) 1058-1068.2. J.-M. R. Génin, R. Aïssa, A. Géhin, M. Abdelmoula, O. Benali, V. Ernstsen, G. Ona-Nguema,C. Upadhyay and C. Ruby, Fougerite and FeII–III hydroxycarbonate green rust; ordering, deprotonation and/or cation substitution; structure of hydrotalcite-like compounds and mythic ferrosic hydroxide Fe(OH)(2+x), Solid State Sci., 7 (2005) 545-572. 3. D. Rodionov, G. Klingelhöfer, B. Bernhardt, C. Schröder, M. Blumers, S. Kane, F. Trolard, G. Bourrié, and . J.-M. R. Génin, Automated Mössbauer spectroscopy in the field and monitoring of fougerite, Hyperfine Interactions, 167 (2006) 869-873.4. C. Ruby, C. Upadhyay, A. Géhin, G. Ona-Nguema and J.-M. R. Génin, In situ redox flexibility of FeII-III oxyhydroxycarbonate green rust and fougerite, Environ. Sci. Technol., 40 (2006) 4696-4702.
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
3 m
78 K
Transmittance (%)
velocity (mm s-1)
DFeII(clay)
DFeII(foug)
DFeIII(clay)
DFeIII(foug)
-4 -2 0 2 4
97
98
99
100
(c)
2 m
78 K
-15 -10 -5 0 5 10 15
97
98
99
100
Transmittance (%)
velocity (mm s-1)
DFeIIS1 + S2
DFeIII(a)
2.50 m
78 K
Transmittance (%)
velocity (mm s-1)
DFeII
DFeIII
S
-10 -5 0 5 10 15
98
99
100
(b)
fougerite
clays
Oxidised zone Reduced zone
FeII
FeIII
FeII FeIII
Fe+2aq
clays
goethite
paramagnetic
Ferricoxyhydroxides
(d)
δ Δ H RA(mm s−1) (mm s−1) (kOe) (mm s−1) (%)
Depth 2 m
DFeIII (para +clay) 0.39 0.65 0.67 55(para +clay)DFeII (clay) 1.17 2.85 0.41 11.7S1 (goethite) 0.37 −0.21 474 0.41 10.6S2 (goethite) 0.38 −0.19 442 0.70 22.5S1 +S2 (goethite) 33
Depth 2.50 mDFeIII 0.39 0.62 0.72 57.7(para+clay+foug)DFeII (clay+ foug) 1.18 2.86 0.44 30.4S (goethite) 0.43 −0.19 468 0.68 11.8
Depth 3 mDFeII (foug) 1.17 2.84 0.37 39DFeIII (foug) 0.39 0.63 0.55 40.5DFeII (clay) 0.96 2.71 0.30 9DFeIII (clay) 0.20 0.48 0.42 11.5
Hyperfine parameters of Mössbauer spectra measured at 78 K of samples extracted in Denmark at different depths of 2 m, 2.50 m, 3 m out of hydric soils from (a) an oxidised zone to (c) a reduced zone. A mixture of fougerite, ferric oxyhydroxides and clay minerals is observed . H: hyperfine field (kOe); δ: isomer shift (mm s−1) with respect to α Fe at room temperature; Δ or ε: quadrupole splitting or shift (mm s−1); Γ : half-width at half maximum (mm s−1); RA: relative abundance (%).
Fougerite is the active mineral that is mixed with clay minerals and responsible for the natural reduction of nitrates in gley soils within the water table.
J.-M. R. Génin, R. Aïssa, A. Géhin, M. Abdelmoula, O. Benali, V. Ernstsen, G. Ona-Nguema,C. Upadhyay and C. Ruby, Fougerite and FeII–III hydroxycarbonate green rust; ordering, deprotonation and/or cation substitution; structure of hydrotalcite-like compounds and mythic ferrosic hydroxide Fe(OH) (2+x), Solid State Sci., 7 (2005) 545-572.