Supporting Information 1 
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Exploring the influence of operational parameters on the reactivity of 
elemental iron materials
C. Noubactep1 (*), T. Licha1, T.B. Scott2, M. Fall3, M. Sauter1 
1 University of Göttingen, Centre of Geosciences - Applied Geology; Goldschmidtstrasse 3, D - 37077 
Göttingen, Germany 
2 Interface Analysis Centre; University of Bristol, England. 
3 University of Ottawa, Department of Civil Engineering, 161 Louis Pasteur, Ottawa, Ontario, Canada K1N 6N5 
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(*) corresponding author: cnoubac@gwdg.de; Tel. +49 551 39 3191, Fax. +49 551 399379 
 
 
Number of pages: 6 
Number of figures: 1 
Number of tables: 3 
 
Contents: 
™ Main characteristics and elemental composition of iron materials used in this study 
(Table SI 1 & 2). 
™ Iron dissolution as function of initial EDTA concentration (Table SI 3). 
™ Discussion on the effect of EDTA initial concentration on iron dissolution (Figure SI 
1a and 1b). 
 
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Table SI 1: Main characteristics and iron content of tested Fe0 materials. 24 
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 origin original denotation  code  form ∅ 
(μm) 
Fe 
(%) 
MAZ, mbH Sorte 69(a) ZVI0  fillings 100-2000 92.8 
G. Maier GmbH FG 0000/0080 ZVI1  powder ≤ 80 92(c)
G. Maier GmbH FG 0000/0200 ZVI2  powder ≤ 200 92(c)
G. Maier GmbH FG 0000/0500 ZVI3  powder ≤ 500 92(c)
G. Maier GmbH FG 0300/2000 ZVI4  fillings 200-2000 92(c)
G. Maier GmbH FG 1000/3000 ZVI5  fillings 1000-3000 92(c)
G. Maier GmbH FG 0350/1200 ZVI6 fillings 100-2000 92(c)
MAZ, mbH Zünder (a) ZVI7 fillings 100-2000 n.d.(b)
Würth Hartgußstrahlmittel ZVI8  spherical 1200 91.5 
Hermens Hartgußgranulat ZVI9 flat 1500 91.5 
G. Maier GmbH Graugußgranulat ZVI10 chips 700-1500 96.7 
ISPAT GmbH Schwammeisen ZVI11 spherical 9000 86.3 
Aldrich Fe, powder ZVI12  powder 10 >99(c)
ACROS Fe, powder, 99% ZVI13  powder 45 99(c)
J. T. Baker Fe ZVI14 fillings  >99(c)
Connelly-GPM CC-1200 ZVI15  powder <850 89.82(c)
Connelly-GPM CC-1190 ZVI16 fillings <2360 89.82(c)
Connelly-GPM CC-1004 ZVI17 fillings <4750 89.82(c)
(a) Scrap iron material; (b) n.d.; (c) average values from material supplier. 26 
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Table SI 2: Elemental composition of iron materials used in this study. 29 
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ZVI  elemental composition (%) 
 C Si Mn P S Cr Mo Ni Fe 
ZVI 0 3.52 2.12 0.93 n.d. (*) n.d. 0.66 n.d. n.d. 92.8 
ZVI 1 – 6(**) 3.20 1.95 n.d. 0.22 n.d. 0.23 n.d. 0.18 92 
ZVI 7 3.13 2.12 0.36 n.d. n.d. 0.077 n.d. 0.056 96.7 
ZVI 8 3.39 0.41 1.10 n.d. 0.105 0.34 n.d. 0.088 91.5 
ZVI 9 3.13 0.17 0.42 0.053 0.065 0.16 n.d. 0.23 n.d. 
ZVI 10 3.13 2.17 0.36 0.022 0.029 0.077 n.d. 0.056 n.d. 
ZVI 11 1.96 0.12 0.09 0.027 0.14 0.003 n.d. (*) <0.001 98.2 
ZVI 12 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 99 
ZVI 13 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 99 
ZVI 14 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. 99 
ZVI 15-
17(**)
2.85 1.85 0.60 0.132 0.107 0.1 0.15 0.13 89.82 
(*) n.d. = not determined and (**) average values from material supplier 31 
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Discussion on the effect of EDTA initial concentration 34 
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The effect of initial EDTA concentrations between 2.5 and 20.0 mM (prepared from 
commercial Na2-EDTA and Milli-Q purified water) was evaluated for ZVI0 (2 g L–1) and the 
deduced characteristic parameters are given in Table SI3. Figure SI 1a summarizes the 
evolution of iron concentration as function of time and Figure SI 1b gives the variation of the 
deduced dissolution rate (kEDTA values) as function of EDTA concentration. 
The results in Table SI3 showed that the iron dissolution rates (kEDTA) increased from 45 to 
500 μg h–1 when the EDTA concentration increased from 2.5 to 20.0 mM. This foreseeable 
observation attests the ability of EDTA to characterize Fe0 reactivity at pH values >5 and 
validates the chosen experimental protocol. It is interesting to note that b values decreased 
with increasing EDTA concentrations and reached a negative value for 20.0 mM ETDA. This 
trend was attributed to the increased solution corrosiveness for Fe0. Aggressive solutions also 
cause too rapid dissolution of fines (atmospheric corrosion products). Based on this 
observation a 20.0 mM EDTA solution was used as washing fluid in pre-treatment 
procedures. Note that at low EDTA concentration b values are primarily a reflect of the 
amount of atmospheric corrosion products on Fe0 [1]. For EDTA >15 mM (see below), b-
values were meaningless. This results shows clearly that the 50 mM EDTA used by Chen et al 
[2] was too aggressive for washing purposes. On the other hand while using EDTA to avoid 
iron precipitation, Abdelouas et al. [3] did not specified used concentrations. Finally, the 
values of τEDTA suggest that, apart from the system with 20.0 mM, all systems need more than 
six days to reach iron saturation. Due to numerous interferences (discussed in the article) only 
a limited number of experimental points (here, 4 ≤ n ≤ 6) yielding actual linearity was used. 
kEDTA and b valued were derived by regression. τEDTA was obtained by resolving the equation 
kEDTA*t  + b = 112. 
Figure SI 1b shows that kEDTA was a linear function of time only for [EDTA] ≤15 mM. A 
jump can be seen between the curve for 15.0 mM and that for 20.0 mM (Figure SI 1a). As the 
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EDTA concentration varies from 15.0 to 20.0 mM the dissolution rate varies from 200 to 500 
μg h
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–1 (Table SI3). 
References 
[1] C. Noubactep, M. Fall, G. Meinrath, B. Merkel, A simple method to select zero valent iron 
material for groundwater remediation. paper presented at the Quebec 2004, 57TH 
Canadian Geotechnical Conference, 5TH Joint CGS/IAH-CNC Conference, Session 1A, 
(2004) 6-13. 
[2] J.-L. Chen, S.R. Al-Abed, J.A. Ryan, Z. Li, Effects of pH on dechlorination of 
trichloroethylene by zero-valent iron, J. Hazard. Mater B83 (2001), 243-254. 
[3] A. Abdelouas, W. Lutze, H.E. Nutall, W. Gong, Réduction de l’U(VI) par le fer 
métallique: application à la dépollution des eaux. C. R. Acad. Sci. Paris Earth Planetary 
Sci. 328 (1999), 315-319. 
 
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Table SI 3: Corresponding correlation parameters (kEDTA, b, R) and τEDTA of iron dissolution 
under various EDTA initial concentrations. General conditions: initial pH 5.2, room 
temperature 23 ± 2 °C, and Fe
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0 (ZVI0) mass loading 2 g L–1. n is the number of experimental 
points for which the curve iron vs. time is linear. a and b-values were calculated in Origin 6.0. 
Parameter n R kEDTA b τEDTA
(mM)   (μg h–1) (μg) (d) 
2.5 6 0.983 43 ± 4 257 ± 106 6.5 
5.0 6 0.996 65 ± 3 300 ± 83 8.8 
7.5 6 0.989 104 ± 8 204 ± 94 8.3 
10.0 6 0.992 158 ± 10 14 ± 79 7.4 
15.0 6 0.994 206 ± 11 33 ± 68 8.5 
20.0 4 0.994 498 ± 39 -897 ± 536 4.8 
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Figure SI 1: Characterization of the iron dissolution from ZVI0 as a function of the EDTA 
concentration: (a) kinetics of iron dissolution for various initial concentrations; 
(b). variation of the rate of iron dissolution (k
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EDTA) as a function of the EDTA 
concentration. Table SI 3 shows that for [EDTA] = 20 mg L-1, only 4 
experimental points (n = 4) were used for regression. 
0 20 40 60 80 100
0
75
150
225
300
375
450
525
600 (a) 2.5 mM 5.0 mM
 7.5 mM
 10.0 mM
 15.0 mM
 20.0 mM
iro
n 
/ [
m
g 
L-
1 ]
elapsed time / [hours]
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85 
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85  
4 8 12 16 20
75
150
225
300
375
k E
D
TA
 / 
[μg
 L
-1
]
EDTA / [mM]
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89 
 
 
 
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