Green rusts and the corrosion
of iron based materials
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,
Département Matériaux et Structures, ESSTIN,
405 rue de Vandoeuvre, F-54600 Villers-lès-Nancy, France.
E-Mail:genin@lcpme.cnrs-nancy.fr
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
Green rusts, i.e. FeII-III hydroxysalts, are layered double
hydroxides (LDH) constituted of [FeII(1-x) FeIIIx (OH)2 ] x+ layers and
[(x/n)An-(mx/n)H2O]x-interlayers.
Anions can be Cl-, CO32-, SO42-, HCOO-, C2O42-,, SeO42- …
For Chloride
Sulphate
Carbonate
[FeII2FeIII(OH)6]+[Cl-2H2O][FeII4FeIII2(OH)12]2+[SO42-8H2O]2[FeII4FeIII2(OH)12]2+[CO32-3H2O]2-
Two types of stacking by XRD: GR1 [R(-3)m] and GR2 [P(-3)m1]
XRD pattern of
hydroxycarbonate
GR1(CO32-).
(thesis of Omar Benali 2002).
R-3m
XRD pattern of
hydroxysulphate
GR2(SO42-)
(thesis of Rabha Aïssa 2004).
P-3m1
100
Transmittance %
Transmittance %
-6
2 ferrous doublets
D1 & D2 (large D)
1 ferric doublet D3
(small D)
x  0.33
96
78 K
94
92
(a)
-4-4
-3 -2-2
D1
D2
Transmittance %
x=
/ Fetotal is
obtained directly
from the spectrum
(RA of D3)
D3
-10 0
12 2
Velocity (mm s-1)
34 4
0.25 < x < 0.33
D1
D2
D3
D3
78 K
(b)
82
-46 -3
D1
-2
-1
0
1 2
Velocity (mm s-1)
3
4
3
4
100
98
98
GR1(CO32-)
97
x = 0.33
78 K
96
95
(c)
94
-4
-3 -2
GR1(Cl-)
0.33
d
x = 0.25
87
99
x
GR1(CO32-)
92
100
FeIII
Experimentally
GR1(Cl-)
D
Transmittance (%)
Transmission
Mössbauer spectra
measured at 78 K of
various Green Rusts
D2
97
98
D2
96
D3
GR2(SO42-)
x = 0.33
94
D1
78 K
92
(d)
90
-1
0
1 2
3
Velocity (mm s-1)
4
GR1(CO32-)
0.25
RA
d
D
mm s-1
%
mm s-1
1.27 2.89 37 1.28 2.97
1.25 2.60 32 1.28 2.55
0.47 0.41 31 0.47 0.43
D1
88
-4 -3
-2 -1 0
1 2
Velocity (mm s-1)
GR1(CO32-)
0.33
RA
%
62
12
26
D3
d
D
RA
mm s-1
%
1.27 2.93 51
1.28 2.64 15
0.47 0.42 34
GR2(SO42-)
0.33
d
D RA
mm s-1 %
1.27 2.88 66
0.47 0.44 34
Most of the time the corrosion of iron ends into a ferric oxyhydroxide FeOOH
that is the result of the oxidation of the green rust by dissolution-precipitation
Eh
0.2
1
-0.2
100
8
Eh
t
0.0
(a)
tf
t
pH
6
4
2
t t
-0.4
Transmittance (%)
pH
0.4
Carbonate containing
medium
2
S1 S 2
Eh and pH monitoring of the
solution with time
Mössbauer spectra during the
oxidation by dissolutionprecipitation
98
D3
96
t2
94
D1
D1, D2, D3 : GR1(CO32-)
doublets
S1 : ferrihydrite sextet
S2, S3 : goethite sextets
D4 : ferrihydrite doublet
g 3
0
100
200
300
time (mn)
400
D2
D1
90
D3
tg
92
-15
102
-10
-5
96
S1 D
4
S2
Transmittance
(%)
100
-5
0
5
V (mm s-1)
D2
10
94
92
15 -15
D3
t1
-10
D1
-5
0
5
V (mm s-1)
90
15 -15
t1 : GR1(CO32-) + some
ferrihydrite
t3
-10
-5
0
5
V (mm s-1)
10
15
t2 : GR1(CO32-) + goethite +
ferrihydrite
100
98
96
tg : GR1(CO32-) alone
94
85
-10
10
S3
98
92
-15
0
5
V (mm s-1)
100
Transmittance (%)
Transmittance (%)
100
95
0
Transmittance (%)
-0.6
10
15
98
S2
t3 : goethite + ferrihydrite
96
94
92
-15
S1
After tf : goethite alone
(O. Benali)
after tf
-10
-5
0
5
V (mm s-1)
10
15
The in situ oxidation of green rusts by deprotonation
Use a strong oxidant such as H2O2, Dry the green rust and oxide in the air,
Violent air oxidation, Oxide in a basic medium…
0.1
d
b
0.0
-0.1
a
-0.2
0.2
0.4
0.6
0.8
1.0
1.2
{2 × [n(H2O2) / n(Fetotal)] + (1/3)}
96
95
78 K
94
-4
-3
-2
-1 0 1 2
Velocity (mm s-1)
x = 0.33
Transmittance %
92
x ~ 0.63
88
84
-4
(c)
78 K
-3
-2
-1 0 1 2
Velocity (mm s-1)
D4
x ~ 0.63
31 %
D3
3
D1
28 %
(c)
32 %
D2
9%
78 K
-1
0
1
2
100
3
Quadrupole splitting D (mm s-1)
(a)
0
4
D1
D2
17 %
1
2
Quadrupole splitting D (mm s-1)
x ~ 0.78
92
88
-4
(d)
78 K
-3
-2
-1 0 1 2 3
Velocity (mm s-1)
x ~ 0.78
D3
D4
4
(d)
43 %
D1 + D2
35 %
22 %
78 K
-1
0
1
2
3
Quadrupole splitting D (mm s-1)
88
x ~ 0.50
(b)
78 K
-3
-2
-1 0 1 2 3
Velocity (mm s-1)
D3
38 %
D4
16.5 %
78 K
4
D1
(b)
33 %
x ~ 0.50
3
96
84
4
D3
78 K
3
92
84
-4
50 %
33 %
1.4
Probability density (p)
Transmittance %
Probability density (p)
96
D3
(a)
-1
100
Transmittance %
c
x = 0.33
D1
Probability density (p)
0.2
97
D2
12.5 %
-1
0
1
2
3
Quadrupole splitting D (mm s-1)
Transmittance %
e
100
98
x=1
96
(e)
78 K
94
Probability density (p)
Transmittance %
0.3
Probability density (p)
Eh(V)
FeII-III oxyhydroxycarbonate FeII6(1-x) FeIII6x O12 H2(7-3x) CO3
100
100
0<x<1
99
96
H
with
H2O2
2 O2
D2
98
-4
-2
0
2
Velocity (mm s-1)
4
D4
x=1
67 %
(e)
D3
33 %
78 K
-1
0
1
2
Quadrupole splitting D (mm s-1)
“Gütlich, Bill, Trautwein: Mössbauer Spectroscopy and Transition Metal Chemistry@Springer-Verlag 2009”
3
GR(CO32-)
x = 0.33
(a)
H2O2
x = 0.50
(b)
0.2 µm
(a)
(c)
10
20
30
Diffraction Angle (2q°)
Intensity (arb. unit)
110 113
012
018
015
006
Intensity (arb. unit)
003
0.2 µm
Aerial
x=1
(d)
(d)
20
30
Diffraction Angle (2q°)
FeII-III
TEM and XRD patterns of the
due to the in situ deprotonation
0.5 µm
(b)
10
40
H2O2
x=1
(c)
40
oxyhydroxycarbonate
0.5 µm
GR1(CO32-)*
400
G
G
C
Oxidation by oxygen
(a) & (b) Dissolutionprecipitation
G
x(O2) =
C
Eh (mV)
200
E
20% …13,3%...6,7% ……….
0
-200
M+G
20% (750 rpm)
(c)
(b)
(1) FeII4FeIII2(OH)12 CO3 + 3/4 O2 →
B 5 FeIIIOOH + CO32- + Fe2+ + 7/2 H2O
(2) 3Fe2+ + (1/4)O2 + (3/2) H2O  a-FeIIIOOH
C + 2 Fe3+ + H
2
(3) FeII4FeIII2(OH)12 CO3 + 1/3 O2 →
D 5/3 FeIIFeIII O + CO 2- + Fe2+ + 6 H O
2
4
3
2
2,7% (375 rpm)
(a)
B
-400
D
Reaction time (min)
tg
0
400 tf
200
800
600
1200
1000
(c) In situ deprotonation
Both modes of oxidation exist depending on the rate of oxygen (4) FeII4FeIII2(OH)12CO3 + O2 →
FeIII6O12H8CO3 + 2 H2O
M
Intensity (u. a.)
G
M
M
G
0
10
G
M
G
M
G
(a)
G
302 q (°) 40 0
10
00.3
GR*
(b)
01.2
GR*
G
G
M
20
lKa(Mo)
G
20
30
2 q (°)
400
00.6
GR*
01.5
GR*
10
20
(c)
01.8
GR*
lKa(Mo)
30
40
2 q (°)
50
Magnetite (M)
+ Goethite (G) 293 K
Goethite (G)
a-FeOOH
293 K
GR*
293 K End products
of oxidation
(A.Renard)
-12
-8
-4
0
4
Velocity (mm s-1)
8
12 -12
-8
-4
0
4
Velocity (mm s-1)
8
12
-12
-8
-4
0
4
Velocity (mm s-1)
8
12
Aqueous corrosion of iron
Fe0
FeII
Iron, Steels
Dissolution
and
Precipitation
Ferrous hydroxide
Agressive anions (Cl-, CO32-, SO42-)
CORROSION
PASSIVATION
Green rusts
FeII-III
Dissolution-precipitation
FeIII
In situ deprotonation
Common rusts
Ferric green rusts
including anions
Goethite, Magnetite, Lepidocrocite, Akaganeite,
d-FeOOH, 0.4
Ferroxyhite
HCO3-
The first step of corrosion:
the green rust layer
CO32Fe(OH)2+
Eh(V)
0.2 H2CO3
FeOH+
0
Eh-pH Pourbaix
diagrams of -0.2
GR(CO32-)
FeOOH-
D1 +D2
D3
a-Fe
Fe++
a-FeOOH
-0.4
GR(CO32-)
[Fe2+] is 10-6 M
In situ
deprotonation
of GR1(CO32-)
-0.6
Fe(OH)2
Fe
-0.8
5
6
7
8
9 10 11 12 13 14 pH
CEMS spectrum at room temperature of a
steel disk dipped 24 hours in a
0.1 M NaHCO3 solution.
GR* is also obtained by bacterial reduction
6
40
Fe(II)
Methanoate
Abiotic control
30
20
10
0
3
0
10
20
30
S (018)
50
GR1 (018)
60
(b)
GR1 (015)
Intensity (a.u.)
9
S (104)
GR1 (012)
(a)
GR1 (003)
70
(a)
GR1 (006)
12
502 q 60
40
100
0
6
12
18
24
30
Time (days)
(d)
Transmittance (%)
Methanoate (mM)
Fe(II) (mM)
80
36
98
96
(c)
Dg 2
bioreduction
D1
D’3 x ~ 0.50
78 K
94
(b)
D
Six days
92
-4
-2
0
Velocity (mm
2
s-1)
4
(c)
(d)
(e)
(A. Zegeye)
5 µm
20 µm
(G. Ona-Nguema)
(c)
Production of Fe(II) and
consumption of
methanoate during
culture of Shewanella
putrefaciens in presence
of lepidocrocite gFeOOH.
The initial amount of
FeIII (as lepidocrocite )
and of methanoate were
respectively 80 mM and
43 Mm.
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.
Mössbauer spectrum
after 6 days of
bioreduction.
TEM observations and
optical micrograph of GR
crystals obtained by
reduction of lepidocrocite
by S. putrefaciens; One
sees the bacteria that
respirate GR*.
Marine corrosion of steel and Microbially influenced corrosion
(c)
(Refait, Génin)
Transmittance (%)
(a) SEM micrograph showing hexagonal shaped crystals of GR(SO42−) upon corroded steel sheet left 25 years in seawater,
(b) sequence of the rust layers: metal–magnetite–lepidocrocite–GR(SO42−), (c) Raman spectrum of the outer part of the marine
corroded layer.
g-FeOOH
100
Experimental
Microbially induced corrosion in
DIRB
D2
98
marine sediments is due to the
Global computed
D3
GR(SO42-)
reduction of oxyhydroxides by
GR: Fe(II) = D1
2GR(SO4 ) dissimilatory iron reducing bacteria
Dg
96
D1
GR: Fe(III) = D3
that respirates FeIII producing
GR: Fe(II) = D2
FeII-III oxyhydroxysulphate followed
SRB
94
77 K
II
Fe
by its reduction into sulfides in
Lepidocrocite = Dg
acidic conditions due to sulphate
92
FeIIS
-4
-2Velocity0(mm s-1)2
4
(A. Zegeye)
reducing bacteria.
Formation of GR2(SO42-) during the reduction of g-FeOOH by a
0
dissimilatory iron-respiring bacterium, Shewanella putrefaciens. Reduction Fe
was performed in a non-buffered medium without any organic compounds,
Mössbauer spectroscopy allowed us to study the family of FeII-III hydroxysalts known as green rusts, which are
intermediate compounds during the corrosion of iron-based materials.
There exist two modes of oxidation of the green rusts, either by dissolution-precipitation that leads to corrosion, or by in
situ deprotonation giving rise to a ferric oxyhydroxysalt, e.g. FeIII6O12H8CO3, that leads to passivation of steels.