colloidal behavior of goethite nanoparticles modified …10.1007/s11051-017-3814... · s1...
TRANSCRIPT
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SUPPLEMENTARY MATERIAL
Colloidal Behavior of Goethite Nanoparticles Modified with Humic
Acid and Implications for Aquifer Reclamation
Journal of Nanoparticle Research
Alberto Tiraferri, Laura Andrea Saldarriaga Hernandez, Carlo Bianco, Tiziana Tosco,
Rajandrea Sethi*
DIATI (Department of Land, Environment and Infrastructure Engineering)
Politecnico di Torino
C.so Duca degli Abruzzi 24, Torino 10129, Italy
Corresponding Author: Tel +39-011-090-7735; Fax: +39-011-090-7699; e-mail: [email protected]
This Supplementary Material file is 11 pages long and it contains 7 figures and 3 tables.
Table of Contents
Figure S1. Electrophoretic mobility of humic acid-coated goethite nanoparticle suspensions as a function of
ionic strength in (a) NaCl, (b) CaCl2, and (c) MgCl2. ...................................................................................... S2
Figure S2. Examples of raw data from aggregation experiments. ................................................................... S3
Figure S3. Apparent aggregation rate as a function of slurry concentration in the presence of 0.7 mM CaCl2.
.......................................................................................................................................................................... S4
Figure S4. Representative results of sedimentation experiments. ................................................................... S5
Table S1. Pictures of sedimentation vials for different doses of calcium. ....................................................... S6
Figure S5. Representative results of sedimentation experiments of suspensions from which most of the
unadsorbed humic acid were removed by filtration. ........................................................................................ S7
Figure S6. Breakthrough curves of humic acid-coated goethite nanoparticles (total solid content of 1.70 g/L)
in silica sand in 10 mM NaCl. .......................................................................................................................... S8
Figure S7. Pictures of the column during transport tests carried out in 1.5 mM CaCl2 and 10.2 g/L solid
content. ............................................................................................................................................................. S9
Table S2. Pictures of sedimentation vials for different dilutions in tap water. .............................................. S10
Table S3. Results of transport tests conducted with suspensions diluted with tap water. ............................. S11
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Figure S1. Electrophoretic mobility of humic acid-coated goethite nanoparticle suspensions as a function of
ionic strength in (a) NaCl, (b) CaCl2, and (c) MgCl2. Mobilities were measured at varying slurry
concentrations. Data points are averages of at least three runs; lines are intended to be used as guide for the
eyes only. Experiments were performed at pH 7.5-8 and at 25°C.
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Figure S2. Examples of raw data from aggregation experiments. Change of hydrodynamic diameter
measured in time for (a) a suspension of 440 mg/L solid content upon addition of 140 mM NaCl, (b) a
suspension of 220 mg/L solid content upon addition of 300 mM NaCl, (c) a suspension of 440 mg/L solid
content upon addition of 300 mM NaCl, (d) a suspension of 110 mg/L solid content upon addition of 1050
mM NaCl. NaCl was added at time zero. Best linear fit of the initial increase in diameter is shown and the
value of its slope is indicated in red. Experiments were conducted at 25°C and at a pH value of 7.5.
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0.0 0.2 0.4 0.6 0.8 1.0
5x10-4
10-3
1.5x10-3
2x10-3
2.5x10-3
3x10-3
0.7 mM CaCl2
no
rma
lized
ap
pa
rent
ag
gre
gation
ra
te
(g/L
)-1(1
/s)
solid concentration (g/L)
44.8 mM NaCl
4x10-7 (g/L)
-1(1/s)
Figure S3. Apparent aggregation rate as a function of slurry concentration in the presence of 0.7 mM CaCl2.
The normalized rate, independent of solid concentration, that would be observed in 44.8 mM NaCl is
equivalent to 4×10‒7
(g/L)‒1
(1/s) and is three order of magnitude lower than the lowest rate measured with
calcium at the largest solid concentration probed in this study. Experiments were conducted at 25°C and at a
pH value of 7.5-8.
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Figure S4. Representative results of sedimentation experiments. Normalized light absorbance of samples at
800 nm wavelength for (a) a solid content of 1.02 g/L and varying concentration of CaCl2, (b) a solid content
of 2.55 g/L and varying concentration of CaCl2, (c) a solid content of 1.70 g/L and varying concentration of
MgCl2. The different concentrations are labeled. Experiments were performed at pH 7.5-8 and at
temperature of 25 °C.
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Table S1. Pictures of sedimentation vials for different doses of calcium.
time 10.2 g/L 5.10 g/L 1.70 g/L
0
10 min
40 min
1.5 hr
3 hr
DI 0.5 1 1.5 2 2.5 mM CaCl2
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Figure S5. Representative results of sedimentation experiments of suspensions from which most of the
unadsorbed humic acid were removed by filtration. Normalized light absorbance of samples at 800 nm
wavelength for (a) a solid content of 1.02 g/L, (b) 1.70 g/L, and (c) 5.10 g/L and varying concentration of
CaCl2. The different concentrations are labeled. Experiments were performed at pH 7.5-8 and at
temperature of 25 °C.
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Figure S6. Breakthrough curves of humic acid-coated goethite nanoparticles (total solid content of 1.70 g/L)
in silica sand in 10 mM NaCl. The nanoparticle suspension was introduced at time 0. The key experimental
conditions were: pH 7.5-8, porosity 0.45, mean grain diameter 0.87 mm, pore volume 10.2 mL, temperature
25 °C, and approach velocity 1.7×10‒4
m/s.
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Figure S7. Pictures of the column during transport tests carried out in 1.5 mM CaCl2 and 10.2 g/L solid
content.
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Table S2. Pictures of sedimentation vials for different dilutions in tap water.
time 10x 20x 40x 60x
20 min
50 min
5 hr
24 hr
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Table S3. Results of transport tests conducted with suspensions diluted with tap water.
dilution comment
60x transport test was impossible; the suspension sedimented in < 1 hour
40x transport test was impossible; the suspension sedimented in < 1 hour
20x the suspension sedimented during injection and was fully sedimented at the end of the
transport test; test was possible as long as the suspension was stable but solids stayed
entrapped in the column after flushing; the average hydrodynamic diameter of the
nanoparticles at the end of the test was 1.59 μm.
Injection suspension at the end of the test
Column appearance during injection
Column appearance at the end of the test after flushing
10x the suspension was stable and the transport test was successful; the column appeared clean
after final flushing; the dimension of the particles in the injection tank was 126 nm at the end
of the test.