Supplementary Materials for
Journal of Nanoparticle Research
Iron Oxide Nanoparticle Synthesis in Aqueous and Membrane Systems
for Oxidative Degradation of Trichloroethylene from Water
Minghui Gui,
1
Vasile Smuleac,
1
Lindell E. Ormsbee,
2
David L. Sedlak,
3
and Dibakar
Bhattacharyya*.1
1
Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY
40506
2
Department of Civil Engineering, University of Kentucky, Lexington, KY 40506
3
Department of Civil and Environmental Engineering, University of California at Berkeley,
Berkeley, CA 94720.
Fig. S1 Size distribution of iron oxide nanoparticles.
Fig. S2 N2 adsorption-desorption isotherms of iron and iron oxide nanoparticles.
Fig. S3 X-ray photoelectron spectroscopy (XPS) of iron oxide nanoparticles.
Fig. S4 Zeta-potentials of iron nanoparticles at pH=4-11.
Table. S1 Iron loading in PAA/PVDF membranes as iron oxide measured by atomic absorption
spectrometer (AAS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES)
Fig. S5 Iron captured by PAA/PVDF membranes during the ion exchange
1
Fig. S1 Size distribution of iron oxide nanoparticles (synthesized by air oxidation of Fe0 in
aqueous phase for 1 h). The dynamic light scattering (DLS) spectrum shows a single peak at the
size of 46.19 nm (width: 12.16 nm) and the z-average diameter is 75.33 nm (PDI: 0.323).
2
Volume of Adsorbed (cm3/g)
Volume of Adsorbed (cm3/g)
140
(a)
120
100
80
60
40
20
0
0
0.2
0.4
0.6
0.8
500
(b)
400
300
200
100
0
1
0
0.2
(c)
400
300
200
100
0
0
0.2
0.4
0.6
0.6
0.8
1
0.8
1
Relative Pressure
500
Volume of adsorbed (cm3/g)
Volume of adsorbed (cm3/g)
Relative Pressure
0.4
0.8
1
60
(d)
50
40
30
20
10
0
0
Relative pressure
0.2
0.4
0.6
Relative pressure
Fig. S2 N2 adsorption-desorption isotherms of fresh iron (a), iron oxide nanoparticles synthesized
by air oxidation of Fe0 in aqueous phase for: (b) 1h, (c) 2h, and (d) γ-Fe2O3 (Aldrich sample). BET
surface area (m2/g): (a) 37.8; (b) 175.5; (c) 253.4; (d): 28.4.
Ferrihydrite is a nanoporous material, made of individual nanocrystals with small size. The
nanoporosity can be proved by the calculation of specific surface area based on the particle size
obtained from SEM images. BET surface area of iron oxide nanoparticles prepared by air
oxidation of Fe0 for 1 h (175 m2/g) was much higher than that calculated from the nonporous
spherical particles with the diameter of 30 nm (19 m2/g). However, TEM shows that the base
particle size is around 3.1 nm which explains the high specific surface area obtained. Nonporous
γ-Fe2O3 nanoparticles (Aldrich, diameter: <50 nm) were also analyzed.
3
10000
6000
O 1s
4000
C 1s
Counts [a.u.]
8000
2000
(a)
0
1000 900 800 700 600 500 400 300 200 100
0
Binding Energy [eV]
45000
3+
Fe 2p3
3+
Fe 2p1
Counts [a.u.]
40000
(b)
35000
Fe 2p1 oxide
Fe 2p3 oxide
30000
(c)
25000
730
725
720
715
710
705
700
Binding Energy [eV]
Fig. S3 X-ray photoelectron spectroscopy (XPS) of iron oxide nanoparticles synthesized by air
oxidation of Fe0 in aqueous phase for 1 h: (a) Wide-scan survey of iron oxide nanoparticles;
High resolution scan spectra of FeCl3 (b, standard) and iron oxide nanoparticles (c).
4
50
ZVINs made without CMC
40
ZVINs made with CMC
Zeta Potential (mV)
30
ZVINs made with CMC aged in the air (20 mL)
for 120 d
20
10
0
-10
-20
-30
-40
-50
4
5
6
7
8
9
10
11
pH
Fig. S4 Zeta-potentials of iron nanoparticles at pH=4-11. [Fe0]=0.1 g/L; Volume of deoxygenated
and deionized water (dispersant): 10 mL.
5
Table. S1 Iron loading in PAA/PVDF membranes as iron oxide measured by atomic absorption
spectrometer (AAS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES)
AAS
Metal concentration before ion
exchange (mM)
Metal concentration after ion
exchange (mM)
Metal in PAA/PVDF by mass
balance (mmol)
ICP-AES
Fe: 386 nm
Fe: 238.204 nm
Na: 568.821 nm
3.480
3.700
0.037
2.810
3.021
1.353
0.134
0.136
0.263
Atomic ratio (Na/Fe)
Blank nitric acid (35 wt%) (mM)
Digested metal in nitric acid (35
wt%) (mM)
Metal in PAA/PVDF by digestion
(mmol)
Atomic ratio (Na/Fe)
1.937
0
0.018
0.136
3.340
3.461
6.657
0.134
0.138
0.261
1.894
The concentrations of iron and sodium ions were measured by ICP-AES (Varian) at the
following wavelengths: Fe: 238.204 nm; Na: 568.821 nm. The calibration curve for each ion was
obtained by diluting the commercial standards (Fisher Scientific) containing 1000 mg/L of the
desired metal with DIUF water. Yttrium chloride (1 mg/L) was added as the internal standard. The
analytical error is less than 3%.
6
Iron Captured in PAA/PVDF (mg)
20
18
16
14
Cycle
Fe captured as iron oxide NPs (mg)
1
2
3
4
17.6
11.9
5.48
1.23
12
10
8
6
4
2
0
1
2
3
4
Cycle No.
Fig. S5 Iron captured by PAA/PVDF membranes during the ion exchange. [FeCl2]= 3.57 mM;
V=200 mL; pH=5.00-5.30.
N2 was bubbled to prevent the oxidation of ferrous ions. After each cycle, the membranes
were reduced by NaBH4 followed by oxidation of compressed air. Then they were washed with
deoxygenated and deionized water, and put in FeCl2 solution for ion exchange again.
7