Cyclodextrin Functionalized Fe3O4@TiO2:Reusable, Magnetic ...
Cyclodextrin Functionalized Fe3O4@TiO2:Reusable, Magnetic Nanoparticles for Photocatalytic Degradation of Endocrine Disrupting Chemicals in Water Supplies Rajesh Chalasani and Sukumaran Vasudevan* Department of Inorganic and Physical Chemistry Indian Institute of Science, Bangalore 560012, INDIA
Supporting Information S1. TGA of Fe3O4@TiO2 and CMCD-Fe3O4@TiO2 nanoparticles. S2. Elemental analysis of CMCD and CMCD-Fe3O4@TiO2 nanoparticles. S3. Core level X-ray Photoelectron Spectroscopy of the CMCD-Fe3O4@TiO2 nanoparticles. S4. Infrared spectral assignments of CMCD and CMCD-Fe3O4@TiO2 nanoparticles. S5. Summary of the Rietveld refinement results for the thermally annealed
Fe3O4@TiO2 nanocrystals. S6. Atomic positions in the thermally annealed Fe3O4@TiO2 nanocrystals as obtained
from a Rietveld analysis of the X-ray diffraction patterns. S7. Efeect of pH on the photocatalytic degradation of BPA and DBP. S8. Mass spectral analysis of BPA and intermediates of the photocatalytic degradation. S9. Photocatalytic degradation of DBP by CMCD-Fe3O4@TiO2 nanoparticles. S10. Mass spectral analysis of DBP and intermediates of the photocatalytic degradation.
TGA of Fe3O4@TiO2 and CMCD-Fe3O4@TiO2 nanoparticles.
100
(a) Weight percentage
90
(b)
80
100
200
300
400
500
600
700
800
T/K
Figure S1. TGA of (a) Fe3O4@TiO2 and (b) CMCD-Fe3O4@TiO2.
Table S2. Elemental analysis of CMCD and CMCD-Fe3O4@TiO2 nanoparticles.
%C
%H
%O
CMCD
42.56
5.38
52.06
CMCD-Fe3O4@TiO2
7.28
1.12
8.25
Core level X-ray Photoelectron Spectroscopy of the CMCD-Fe3O4@TiO2 nanoparticles. (a)
CMCD-Fe3O4@TiO2 bulk TiO2
724.2ev
711.1ev
(b)
Intensity (a. u)
Intensity (a. u.)
700
459.4
465.2
460
465
CMCD-Fe3O4@TiO2 bulk Fe3O4 710
720
730
450
455
Binding energy (ev)
470
Binding energy (ev)
Figure S3. Core level XPS spectra of CMCD-Fe3O4@TiO2 nanoparticles (a) Fe 2p and (b) Ti 2p regions. The spectra of bulk Fe3O4 and TiO2 are also shown X-ray photoelectron spectroscopy was used to examine the oxidation state of iron and titanium in the CMCD-Fe3O4@TiO2 nanocrystals. The XPS of the Fe3O4@TiO2 nanocrystals along with that of bulk magnetite (Fe3O4) and bulk anatase (TiO2) fine powders were recorded on a Thermo Fisher Scientific Multilab 2000 spectrometer using a Mg Kα source. Figures (S3a) and (S3b) show the representative Fe 2p and Ti 2p core-level XPS spectra. It is known that the Fe 2p core levels of ferrous and ferric can both be detected and distinguished. The observed peaks for Fe3O4@TiO2 nanoparticles at 711.1ev and 724.2ev are the characteristic doublet from Fe 2p3/2 and Fe 2p1/2 core-level electrons for Fe3O4. Similarly the observed peaks for Fe3O4@TiO2 nanoparticles at 459.4 and 465.2 are the characteristic Ti 2p3/2 and Ti 2p1/2 core level doublet for TiO2.
475
Table S4. Infrared spectral assignments of CMCD and CMCD-Fe3O4@TiO2 nanoparticles.
Infrared (cm-1) CMCD
CMCD-Fe3O4
Assignment
759
757
Internal rotation modes about CH2OH (side)
947
949
C-C stretch
1158
1155
C-O stretch
1204,1237,1332
1205,1242,1328
C-O-H bending (coupled modes)
1418
Symmetric C-O stretching of COOgroup
1457
O-C-H
1558
asymmetric C-O stretching of COO- group
1457
1735 2929
C=O stretching of carboxylic acid 2927
C-H stretch
Table S5. Summary of the Rietveld refinement results for the thermally annealed Fe3O4 @TiO2 nanocrystals.
Phase 1
Phase 2
Fe3O4 (magnetite)
TiO2 (Anatase)
Space group
F d -3 m
I 41 / a m d
Lattice parameters
a = 8.3755 Å
a = 3.7866 Å
Preferred Orientation
Nil
Nil
Weight Percentage
73%
27%
Statistical indices, χ2
3.92
Table S6. Atomic positions in the thermally annealed Fe3O4@TiO2 nanocrystals as obtained from a Rietveld analysis of the X-ray diffraction pattern.
x
y
z
site
occupancy
Fe
Oxidation state +3
0.12500
0.12500
0.12500
8a
1.00000
Fe
+2
0.50000
0.50000
0.50000
16d
1.00000
O
-2
0.25597
0.25597
0.25597
32e
1.00000
Anatase
Atom
x
y
z
site
occupancy
Ti
Oxidation state +4
0.00000
0.25000
0.37500
4b
1.00000
O
-2
0.50000
0.25000
0.16497
8e
1.00000
Magnetite
Atom
Effect of pH on the photocatalytic degradation of BPA and DBP. 100
BPA
(a)
100
(b)
DBP
80
% Degradation
% Degradation
60
75
50
40 4
6
8
10
12
4
6
pH
8
10
12
pH
Figure S7. Effect of initial pH on the photocatalytic degradation of (a) BPA and (b) DBP
The effect of the initial pH of the dispersion on the photocatalytic degradation of BPA and DBP by CMCD-Fe3O4@TiO2 was investigated. The pH of the dispersions was adjusted from 4 to 12 by addition of either dilute HCl or dilute NaOH. It was observed that the degradation efficiency is maximum for pH values in the range of 7-9 (for BPA) and 7-10 for DBP.
Mass spectral analysis of BPA and intermediates of the photocatalytic degradation.
%
1 0 0
5 0
(a)
(b) OH
m/z = 133
0
1 0 0
m/z = 163
%
OH
HO
5 0
0 1 0 0
m/z = 203
%
OH
5 0 O HO
0 1 0 0
m/z = 269
HO
%
OH HO
5 0
OH O
0 1 0 0
%
m/z = 189
5 0
OH
0 1 0 0
m/z = 243
%
5 0
HO
OH
OH
0
1 0 0
m/z = 227
%
5 0
HO
OH
0
100
150
200
Mass (m/z)
250
300
100
150
200
250
300
Mass (m/z)
Figure S8. (a) Mass spectra of proposed structures of six main peaks along with BPA. (b) and their corresponding MS/MS spectra.
Photocatalytic degradation of DBP by CMCD-Fe3O4@TiO2 nanoparticles. O
(a)
m/z = 279
279
OH
O O
O
m/z = 249, 193, 221 237
m/z = 265
221
m/z = 293
HO
O OH
69
193
O
O
O
m/z =
O
O
249
O
O
H
O
0 min
(b)
15 min
30 min
45 min
60 min
75 min 90 min 2
4
6
8
12
13
Retention time (min)
Figure S9. Photocatalytic degradation of dibutyl phthalate by CMCD-Fe3O4@TiO2. (a) LC-MS chromatograms for different UV-irradiation times. The time in minutes is indicated. The m/z values of the ions corresponding to the species with different retention times are also indicated (b) Evolution of the products of the photodegradation of DBP
with irradiation time. The
molecular species corresponding to the different m/z ions is shown.
The chromatograms for the degradation of DBP for seven different UV-exposure times are shown in Figure S9a. The products at different retention times were mass-analyzed in the negative ion mode and their evolution with irradiation time displayed in Figure S9b. The six main product ions seen in the degradation of DBP appearing at different retention times are m/z 237, m/z 249, m/z 193, m/z 221, m/z 265 and m/z 293. The m/z 279 ion (retention time = 12.5min)
observed in the chromatograms at short exposure times is identified as the protonated DBP molecular ion.
After 60 minutes of UV-exposure this ion is no longer observed in the
chromatograms. Ions with molecular weight m/z 293 observed in the chromatograms recorded after irradiation for 15 minutes and 30 minutes suggest that the first step in the photocatalytic degradation is the reaction of hydroxyl radicals with the phenyl ring of DBP.
Mass spectral analysis of DBP and intermediates of the photocatalytic degradation.
1 0 0
(a)
(b) OH
O
%
m/z = 237
O
5 0
OH
O
0 1 0 0
m/z = 249
%
OH
O
5 0
O
O
0 1 0 0
m/z = 193 O
%
HO O
5 0
0 1 0 0
m/z = 221 O
%
O
5 0 OH
O
0
1 0 0
m/z = 265
%
OH
O
5 0
O OH
O
0 1 0 0
m/z = 293 O
%
O
5 0
O HO O
0 1 0 0
m/z = 279 O
%
O
5 0
O
O
100
150
200
250
300
100
150
200
250
300
Figure S10. (a) Mass spectra of proposed structures of six main peaks along with DBP. (b) and their corresponding MS/MS spectra.
Supporting Information S1. TGA of Fe3O4@TiO2 and CMCD-Fe3O4@TiO2 nanoparticles. S2. Elemental analysis of CMCD and CMCD-Fe3O4@TiO2 nanoparticles. S3. Core level X-ray Photoelectron Spectroscopy of the CMCD-Fe3O4@TiO2 nanoparticles. S4. Infrared spectral assignments of CMCD and CMCD-Fe3O4@TiO2 nanoparticles. S5. Summary of the Rietveld refinement results for the thermally annealed
Fe3O4@TiO2 nanocrystals. S6. Atomic positions in the thermally annealed Fe3O4@TiO2 nanocrystals as obtained
from a Rietveld analysis of the X-ray diffraction patterns. S7. Efeect of pH on the photocatalytic degradation of BPA and DBP. S8. Mass spectral analysis of BPA and intermediates of the photocatalytic degradation. S9. Photocatalytic degradation of DBP by CMCD-Fe3O4@TiO2 nanoparticles. S10. Mass spectral analysis of DBP and intermediates of the photocatalytic degradation.
TGA of Fe3O4@TiO2 and CMCD-Fe3O4@TiO2 nanoparticles.
100
(a) Weight percentage
90
(b)
80
100
200
300
400
500
600
700
800
T/K
Figure S1. TGA of (a) Fe3O4@TiO2 and (b) CMCD-Fe3O4@TiO2.
Table S2. Elemental analysis of CMCD and CMCD-Fe3O4@TiO2 nanoparticles.
%C
%H
%O
CMCD
42.56
5.38
52.06
CMCD-Fe3O4@TiO2
7.28
1.12
8.25
Core level X-ray Photoelectron Spectroscopy of the CMCD-Fe3O4@TiO2 nanoparticles. (a)
CMCD-Fe3O4@TiO2 bulk TiO2
724.2ev
711.1ev
(b)
Intensity (a. u)
Intensity (a. u.)
700
459.4
465.2
460
465
CMCD-Fe3O4@TiO2 bulk Fe3O4 710
720
730
450
455
Binding energy (ev)
470
Binding energy (ev)
Figure S3. Core level XPS spectra of CMCD-Fe3O4@TiO2 nanoparticles (a) Fe 2p and (b) Ti 2p regions. The spectra of bulk Fe3O4 and TiO2 are also shown X-ray photoelectron spectroscopy was used to examine the oxidation state of iron and titanium in the CMCD-Fe3O4@TiO2 nanocrystals. The XPS of the Fe3O4@TiO2 nanocrystals along with that of bulk magnetite (Fe3O4) and bulk anatase (TiO2) fine powders were recorded on a Thermo Fisher Scientific Multilab 2000 spectrometer using a Mg Kα source. Figures (S3a) and (S3b) show the representative Fe 2p and Ti 2p core-level XPS spectra. It is known that the Fe 2p core levels of ferrous and ferric can both be detected and distinguished. The observed peaks for Fe3O4@TiO2 nanoparticles at 711.1ev and 724.2ev are the characteristic doublet from Fe 2p3/2 and Fe 2p1/2 core-level electrons for Fe3O4. Similarly the observed peaks for Fe3O4@TiO2 nanoparticles at 459.4 and 465.2 are the characteristic Ti 2p3/2 and Ti 2p1/2 core level doublet for TiO2.
475
Table S4. Infrared spectral assignments of CMCD and CMCD-Fe3O4@TiO2 nanoparticles.
Infrared (cm-1) CMCD
CMCD-Fe3O4
Assignment
759
757
Internal rotation modes about CH2OH (side)
947
949
C-C stretch
1158
1155
C-O stretch
1204,1237,1332
1205,1242,1328
C-O-H bending (coupled modes)
1418
Symmetric C-O stretching of COOgroup
1457
O-C-H
1558
asymmetric C-O stretching of COO- group
1457
1735 2929
C=O stretching of carboxylic acid 2927
C-H stretch
Table S5. Summary of the Rietveld refinement results for the thermally annealed Fe3O4 @TiO2 nanocrystals.
Phase 1
Phase 2
Fe3O4 (magnetite)
TiO2 (Anatase)
Space group
F d -3 m
I 41 / a m d
Lattice parameters
a = 8.3755 Å
a = 3.7866 Å
Preferred Orientation
Nil
Nil
Weight Percentage
73%
27%
Statistical indices, χ2
3.92
Table S6. Atomic positions in the thermally annealed Fe3O4@TiO2 nanocrystals as obtained from a Rietveld analysis of the X-ray diffraction pattern.
x
y
z
site
occupancy
Fe
Oxidation state +3
0.12500
0.12500
0.12500
8a
1.00000
Fe
+2
0.50000
0.50000
0.50000
16d
1.00000
O
-2
0.25597
0.25597
0.25597
32e
1.00000
Anatase
Atom
x
y
z
site
occupancy
Ti
Oxidation state +4
0.00000
0.25000
0.37500
4b
1.00000
O
-2
0.50000
0.25000
0.16497
8e
1.00000
Magnetite
Atom
Effect of pH on the photocatalytic degradation of BPA and DBP. 100
BPA
(a)
100
(b)
DBP
80
% Degradation
% Degradation
60
75
50
40 4
6
8
10
12
4
6
pH
8
10
12
pH
Figure S7. Effect of initial pH on the photocatalytic degradation of (a) BPA and (b) DBP
The effect of the initial pH of the dispersion on the photocatalytic degradation of BPA and DBP by CMCD-Fe3O4@TiO2 was investigated. The pH of the dispersions was adjusted from 4 to 12 by addition of either dilute HCl or dilute NaOH. It was observed that the degradation efficiency is maximum for pH values in the range of 7-9 (for BPA) and 7-10 for DBP.
Mass spectral analysis of BPA and intermediates of the photocatalytic degradation.
%
1 0 0
5 0
(a)
(b) OH
m/z = 133
0
1 0 0
m/z = 163
%
OH
HO
5 0
0 1 0 0
m/z = 203
%
OH
5 0 O HO
0 1 0 0
m/z = 269
HO
%
OH HO
5 0
OH O
0 1 0 0
%
m/z = 189
5 0
OH
0 1 0 0
m/z = 243
%
5 0
HO
OH
OH
0
1 0 0
m/z = 227
%
5 0
HO
OH
0
100
150
200
Mass (m/z)
250
300
100
150
200
250
300
Mass (m/z)
Figure S8. (a) Mass spectra of proposed structures of six main peaks along with BPA. (b) and their corresponding MS/MS spectra.
Photocatalytic degradation of DBP by CMCD-Fe3O4@TiO2 nanoparticles. O
(a)
m/z = 279
279
OH
O O
O
m/z = 249, 193, 221 237
m/z = 265
221
m/z = 293
HO
O OH
69
193
O
O
O
m/z =
O
O
249
O
O
H
O
0 min
(b)
15 min
30 min
45 min
60 min
75 min 90 min 2
4
6
8
12
13
Retention time (min)
Figure S9. Photocatalytic degradation of dibutyl phthalate by CMCD-Fe3O4@TiO2. (a) LC-MS chromatograms for different UV-irradiation times. The time in minutes is indicated. The m/z values of the ions corresponding to the species with different retention times are also indicated (b) Evolution of the products of the photodegradation of DBP
with irradiation time. The
molecular species corresponding to the different m/z ions is shown.
The chromatograms for the degradation of DBP for seven different UV-exposure times are shown in Figure S9a. The products at different retention times were mass-analyzed in the negative ion mode and their evolution with irradiation time displayed in Figure S9b. The six main product ions seen in the degradation of DBP appearing at different retention times are m/z 237, m/z 249, m/z 193, m/z 221, m/z 265 and m/z 293. The m/z 279 ion (retention time = 12.5min)
observed in the chromatograms at short exposure times is identified as the protonated DBP molecular ion.
After 60 minutes of UV-exposure this ion is no longer observed in the
chromatograms. Ions with molecular weight m/z 293 observed in the chromatograms recorded after irradiation for 15 minutes and 30 minutes suggest that the first step in the photocatalytic degradation is the reaction of hydroxyl radicals with the phenyl ring of DBP.
Mass spectral analysis of DBP and intermediates of the photocatalytic degradation.
1 0 0
(a)
(b) OH
O
%
m/z = 237
O
5 0
OH
O
0 1 0 0
m/z = 249
%
OH
O
5 0
O
O
0 1 0 0
m/z = 193 O
%
HO O
5 0
0 1 0 0
m/z = 221 O
%
O
5 0 OH
O
0
1 0 0
m/z = 265
%
OH
O
5 0
O OH
O
0 1 0 0
m/z = 293 O
%
O
5 0
O HO O
0 1 0 0
m/z = 279 O
%
O
5 0
O
O
100
150
200
250
300
100
150
200
250
300
Figure S10. (a) Mass spectra of proposed structures of six main peaks along with DBP. (b) and their corresponding MS/MS spectra.
