Supplementary Data
Solid Surface Photochemistry of montmorillonite: Mechanisms
of Arsenite Oxidation under UV-A Irradiation
Yanan Yuan a, Yajie Wang a,b, Wei Ding a, Jinjun Li a**, Feng Wu a*
a
Department of Environmental Science, Hubei Key Lab of Biomass Resource Chemistry and
Environmental Biotechnology, School of Resources and Environmental Science, Wuhan University,
Wuhan, 430079, P. R. CHINA
b
School of Chemistry and Environmental Science, Guizhou Minzu University, Guiyang, 550025, P. R
CHINA
*Corresponding author. Tel: 86-27-68778511, Fax: 86-27-68778511, E-mail: fengwu@whu.edu.cn.
**Co-corresponding author. Tel: 86-27-68778511, Fax: 86-27-68778511, E-mail: ljj0410@163.com.
1. Experimental setup
1
Fig. S1. Setup for photooxidation of As(III) on the montmorillonite layer. The temperature and relative
moisture of the chamber was maintained at 20 ± 2 °C and 70%, respectively.
2. The emission spectrum of the lamp used for photooxidation
Fig. S2. Emission spectrum of the black-light lamp, the main emission wavelength was at 365 nm.
2
3. Dark experiment at different initial As(III) concentration
-1
[As(III)]0 (g g )
100;
50;
200
150;
150
-1
[As(III)] (g g )
200
100
50
0
0
20
40
80
60
time (h)
100
120
Fig. S3. Effects of initial concentration on As(III) dark reaction. Experimental conditions: pH 6.8, 70%
RH.
Table S1 The extraction efficiencies of [As]total in controlling experiment. Experiment conditions:
[As(III)]0 =100 μg g-1，pH 6.8，70% RH.
Time (h)
0
24
48
72
96
120
As(total) photoreaction (μg g-1)
102.19
98.84
99.87
98.16
99.97
95.81
As(total) dark reaction (μg g-1)
97.92
97.48
94.32
99.48
99.47
100.64
4. Dark experiment at different pH values
3
-1
[As(III)] (g g )
90
80
70
pH = 8.5
pH = 6.8
pH = 5.2
pH = 4.3
60
50
0
20
40
80
60
time (h)
100
120
Fig. S4. Effect of pH value on As(III) dark reaction. Experiment conditions: [As(III)]0 =100.0 μg g-1, 70%
RH.
5. Effect of layer thickness in dark
Table S2 The relationship between thickness and mass of slurry applied.
Mass of slurry applied (g)
Thickness (mm)
7.5
0.052±0.001
15
0.104±0.001
22.5
0.162±0.001
30
0.210±0.003
4
-1
[As(III)] (g g )
95
90
85
80
z = 0.052 mm
z = 0.104 mm
z = 0.162 mm
z = 0.210 mm
75
70
65
0
20
40
60
80
time (h)
100
120
Fig. S5. Effect of thickness on As(III) dark reaction. Experiment conditions: [As(III)]0 =100.0 μg g-1,
pH 6.8, 70% RH.
6. Effect of HA in dark experiment
5
HA
HA+montorillonite
montmorillonite
relative intensity
2.0
1.6
1.2
0.8
0.4
0.0
200
300
400
500
600
700
800
wavelength (nm)
Fig. S6. Diffuse reflectance spectra of montmorillonite with and without HA. The conditions: 100%
montmorillonite, 100% HA, and 5% HA + 95% montmorillonite.
-1
[As(III)] (g g )
90
80
-1
[HA]0 (g g )
1000
500
250
125
0
70
60
0
20
40
60
80
time (h)
6
100
120
Fig. S7. Effect of HA on As(III) dark reaction. Experiment conditions: [As(III)]0 =100.0 μg g-1, pH 5.2,
70% RH.
7. Effect of additional iron ions in dark experiment
-1
[As(III)] (g g )
90
80
-1
[Fe(III)]0 (g g )
0
1.0
10.0
100.0
70
60
0
20
40
60
80
100
120
time (h)
Fig. S8. Effect of Fe(III) on As(III) dark reaction. Experiment conditions: [As(III)]0 =100.0 μg g-1, pH
5.2, 70% RH.
7
-1
[As(III)] (g g )
90
80
-1
[Fe(II)]0 (g g )
70
0
1.0
10.0
100.0
60
0
20
40
60
80
100
120
time (h)
Fig. S9. Effect of Fe(II) on As(III) dark reaction. Experiment conditions: [As(III)]0 =100.0 μg g-1, pH
5.2, 70% RH.
8 The influence of different radical scavengers on As(III) adsorption/desorption
in dark
8
Csupernatant/Ctotal (%)
100
A: None
B: 19.6 mol g-1 CCl4
80
C: 0.1 mol g-1 THB
D: 0.5 mol g-1 THB
E: 1.0 mol g-1 THB
F: 10.0 mol g-1 THB
60
40
20
0
A
C
B
D
E
F
Fig. S10. The influence of different radical scavengers on As(III) desorption in dark. where Csupernatant is
the As(III) concentration in supernatant, Ctotal is the total concentration of As(III) in samples.
Experimental conditions: [As(III)]0 = 100 μg g−1, pH 4.3, 70 % RH.
Cextracted /Ctotal (%)
100
A: None
B: 19.6 mol g-1 CCl4
C: 0.1 mol g-1 THB
D: 0.5 mol g-1 THB
E: 1.0 mol g-1 THB
F: 10.0 mol g-1 THB
80
60
40
20
0
A
B
C
D
E
F
Fig. S11. The influence of different radical scavengers on As(III) uptake in dark. where C extracted is the
extracted As(III) concentration, Ctotal is the total concentration of As(III) in samples. Experimental
9
conditions: [As(III)]0 = 100 μg g−1, pH 4.3, 70 % RH.
10