Photochemical Behavior of Carbon Nanotubes in Natural Waters: Reactive Oxygen Species Production and Effects on •OH Generation by Suwannee River Fulvic Acid, Nitrate and Fe (III)
Lei Zhou a, b,#·Ya Zhang c, #· Qi Wang a· Corinne Ferronatob· Xi Yang a,*· Jean-Marc Chovelonb, **
a State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, P.R. China
b Université Lyon 1, UMR CNRS 5256, Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), 2 Avenue Albert Einstein, F-69626 Villeurbanne, France
c Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People’s Republic of China, Nanjing 210042, P.R. China
*Corresponding author
Prof. Xi Yang
School of the Environment, Nanjing University, Nanjing, 210046, China
Tel/Fax: +86-25-8968 0357
Email:
**Corresponding author
Prof. Jean-Marc Chovelon, Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON)
Université Claude Bernard Lyon 1, Villeurbanne, 69626, France
Tel: +33-0472432638, Fax: +33-0472448114
Email:
#These two authors contributed equally to this paper.
Supplementary Materials
Table S1. The parameters of 3 selected CNTs
Type / Purity / Inner diameter (nm) / Outer diameter (nm) / Length (nm) / BET (m2/g) / Tapdensity / Functional group contentSWCNT / ˃ 90% / 0.8-1.6 / 1-2 / 5-30 / > 380 / 0.14 / 0
MWCNT-OH / ˃ 95% / 5-10 / 10-20 / 10-30 / > 200 / 0.22 / 3,06%
MWCNT-COOH / ˃ 95% / 5-10 / 10-20 / 10-30 / > 200 / 0.22 / 2,00%
Table S2. HPLC analysis parameters.
Compound / Separationa column / Flow rate （mLmin-1） / Mobile phase composition / Injection volume （μL） / Detectionwavelength （nm）
water / methanol
ATL / TC-C18 / 0.8 / 70%b / 30% / 20 / 224
FFA / Zorbax SB-C18 / 1.0 / 40% / 60% / 20 / 216
a The specification of the columns: 250 mm × 4.6 mm, 5 μm,all the columns were purchased from Agilent, b the water phase contained 0.01M ammonium acetate.
Table S3. Standard curves of 3 kinds of CNTs
Type / standard curve / wavelength (nm) / R2SWCNT / TOC = 14.21× Abs / 400 / 0.9971
MWCNT-OH / TOC = 14.99× Abs / 400 / 0.9997
MWCNT-COOH / TOC = 23.70× Abs / 520 / 0.9993
The range of linear fit for the standard curve was 0.1 – 20 mg C L-1.
Table S4. Steady-state concentration of 1O2and·OH in irradiated SRFA (10 mg C L-1) solution.
DOM / [·OH]ss×1016 M / [1O2]ss×1013 MSRFA / 5.96 ± 0.52 / 1.79 ± 0.03
Table S5. Adsorption equations of Fe3+ on MWCNT-OH and MWCNT-COOH.
CNT type / adsorption equation / R2MWCNT-OH / log q =0.9363 × log C - 0.3544 / 0.9696
MWCNT-COOH / log q =0.5511 × log C - 0.2274 / 0.9090
Figure S3 shows the adsorption isotherms of Fe3+ on MWCNT-OH and MWCNT-COOH suspensions, indicating that the Freundlich isotherms better describe the experimental data rather than Langmuir isotherms. The expression for the Freundlich isotherm is as following:
q = KFC1/n(12)
after the logarithm,
logq = 1/nlogC + log KF(13)
whereC is the equilibrium concentration of Fe3+, q is the amount of adsorbed Fe3+. Table S3 displays the adsorption equations of Fe3+ on MWCNT-OH and MWCNT-COOH.
Figure S1. TEM of CNTs before and after ultrasonic dispersion (using MWCNT-COOH as an example)
.
Figure S2. Effects of ionic strength and pH on the stability of CNTs colloidal solution(using MWCNT-COOH as an example)
.
Figure S3. Adsorption isotherms of Fe3+on MWCNT-OH and MWCNT-COOH (pH = 3.5).
Figure S4. The impact of MWCNT-OH on the generation of ·OH by Fe3+-SRFA system ([Fe3+]0 = 45 μM, [SRFA]0 = 5 mgC L-1, [ATL]0 = 10 μM, pH = 6.3).
Figure S5. Irradiance spectra of the xenon lamp used in the experiments (Filters were used to cut off the light with wavelength less than 280 nm).
Figure S6. UV-Vis absorptive spectrum of 3 kinds of CNs. ([CNTs]0= 5 mg C L-1, pH = 6.3).