The Fe II-III oxyhydroxycarbonate fougerite mineral and green rusts in hydromorphic soils

“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”


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.


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


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.


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


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 %


84

88

92

96

100

Transmittance %

(b)

x ~ 0.50

78 K

-4 -3 -2 -1 0 1 2 3 4Velocity (mm s-1)


D3

32 %

D4

31 %

78 K


(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)}


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


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”


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


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.


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


(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.


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.

Documents

The Fe II-III oxyhydroxycarbonate fougerite mineral and green rusts in hydromorphic soils