Predominantly Exposed Facets and Their Heterogeneous. UVA/Fenton Catalytic Activity

Transcription

1 Supporting Information Microwave-Assisted Synthesis of Fe 3 O 4 Nanocrystals with Predominantly Exposed Facets and Their Heterogeneous UVA/Fenton Catalytic Activity Yuanhong Zhong, Lin Yu,, * Zhi-Feng Chen, Hongping He, Fei Ye, Gao Cheng, and Qianxin Zhang School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou , China Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou , China CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou , China. *To whom correspondence should be addressed: L.Yu: gych@gdut.edu.cn S-1

2 Number of pages: 20 Number of texts: 1 Number of tables: 6 Number of figures: 12 Contents Text S1. Experimental procedures for heterogeneous UVA/Fenton catalytic activity tests. Table S1. The synthetic route, additional amount of reagents and reaction time of the prepared magnetite samples. Table S2. Fitting parameters of Fe 2p spectra. Table S3. The hyperfine parameters obtained from fitting of the Mössbauer spectra by sextets. Table S4 Saturation magnetization (M s ) and coercivity (H c ) values of the Fe 3 O 4 samples read from the M H curve. Table S5. Fitted kinetic parameters of the AOII degradation by UVA/Fenton reactions. Table S6. The Fe leaching concentration during the heterogeneous UVA/Fenton catalytic reactions. Figure S1 HRTEM analysis of the Fe 3 O 4 R, the lattice d-spacing corresponding to the known {211} and {311}. S-2

3 Figure S2 Fitting results of Fe 2p spectra in the assignment of Fe 2+ and Fe 3+. Figure S3 Fitting results of O 1s spectra. Figure S4 Room temperature magnetic hysteresis loops of the as-obtained Fe 3 O 4 NPs (Inset: magnified view). Figure S5 UV-vis spectral changes for AOII degradation with Fe 3 O 4 NPs by UVA/Fenton process. Figure S6 Mineralization efficiency of AOII after UVA/Fenton reaction 180 min catalyzed by Fe 3 O 4 NPs. Figure S7 The DMPO spin-trapping ESR spectra for hydroxyl radical ( OH) in aqueous solution generated by H 2 O 2 and Fenton systems under UVA irradiation. Figure S8. The DMPO spin-trapping ESR spectra for superoxide radical (O 2 ) in methanol medium generated by H 2 O 2 and Fenton systems under UVA irradiation. Figure S9 Comparison of degradation efficiency with and without the scavenger DMSO in reaction solution containing Fe 3 O 4 S. Figure S10 Degradation of AOII with the used Fe 3 O 4 S catalyst for four consecutive experiments. Figure S11 X-ray diffraction patterns of the fresh and used Fe 3 O 4 S NPs. Figure S12 SEM images of the used Fe 3 O 4 S NPs. S-3

4 Text S1. Experimental procedures for heterogeneous UVA/Fenton catalytic activity tests. In a typical process, 50 ml of AOII (100 mg L 1 ) aqueous solution was prepared and the ph value was adjusted to 3.0 before the reaction began. After adding the magnetite (0.5 g L 1 ) into the solution, the suspension was stirred for 30 min in dark until the adsorption-desorption equilibrium was achieved. The reaction time was initiated by simultaneously adding H 2 O 2 (20.0 mmol) and turning on the UVA lamp. The reaction solution was sampled at given intervals and followed by centrifugal separation. Subsequently, one milliliter (ml) supernatant was taken out and immediately diluted to 10.0 ml, and monitored the concentration of AOII by UV-vis spectroscopy SHMADZU UV-2700 at λ max = 484 nm. The UV-vis spectral changes between 280~600 nm were measured in order to trace the degradation products.two reference experiments, (i) with light irradiation in the absence of catalyst (With H 2 O 2 only), and (ii) without catalyst and H 2 O 2 (Blank) were also undertaken. At the end of the catalytic test, the leaching Fe ions concentration was determined using a Flame Atomic Absorption Spectrophotometer (FAAS) Hitachi Z 2000 at nm, with a hollow-cathode lamps operating at 30 ma and an acetylene air-flame. After reaction, the Fe 3 O 4 NPs was separated by a magnet, and washed three times with ethanol, then re-employed for cyclic reactions after freeze-dried in vacuum. S-4

5 Table S1. The synthetic route, additional amount of reagents and reaction time of the prepared magnetite samples. samples synthetic path reagents/mmol a Fe 2 SO 4 7H 2 O NaOH NaNO 3 PEG600 b PVP c CH 3 COOH d H 2 O d reaction time/min Fe 3 O 4 N coprecipitation Fe 3 O 4 S microwave reflux Fe 3 O 4 R microwave reflux Fe 3 O 4 C microwave reflux Fe 3 O 4 O microwave reflux Fe 3 O 4 P microwave reflux a, Without specifically stating, the unit is mmol. b, Polyethylene Glycol 600, ml c, polyvinylpyrrolidone, g. d, The volume is measured by ml. S-5

6 Table S2. Fitting parameters of Fe 2p spectra. sample peak center (ev) * Fe 3 O 4 N Fe 3 O 4 S Fe 3 O 4 R Fe 3 O 4 C Fe 3 O 4 O Fe 3 O 4 P * The value of %GL fixed to 20%. S-6

7 Table S3. The hyperfine parameters obtained from fitting of the Mössbauer spectra by sextets. sample subspectra H hf (koe) QS (mm/s) IS (mm/s) W (mm/s) RA (%) Fe 3 O 4 N Sextet A Sextet B Doublet Fe 3 O 4 O Sextet A Sextet B Doublet Fe 3 O 4 R Sextet A Sextet B Sextet ,2 Sextet Doublet Doublet Fe 3 O 4 P Sextet A Sextet B Sextet Sextet Sextet Sextet Doublet Doublet H hf, hyperfine magnetic field; QS, quadrupole splitting; IS, isomer shift relative to α Fe; W, resonance half-height line width; RA, relative sub-spectral area. S-7

8 Table S4 Saturation magnetization (M s ) and coercivity (H c ) values of the Fe 3 O 4 samples read from the M H curve. sample M s (emu/g) M r (emu/g) H c (Oe) M r /M s Fe 3 O 4 N Fe 3 O 4 S Fe 3 O 4 R Fe 3 O 4 C Fe 3 O 4 O Fe 3 O 4 P S-8

9 Table S5. Fitted kinetic parameters of the AOII degradation by UVA/Fenton reaction. samples k app ( 10 3 min 1 ) t 1/2 (min) R 2 H 2 O Fe 3 O 4 N Fe 3 O 4 S Fe 3 O 4 R Fe 3 O 4 C Fe 3 O 4 O Fe 3 O 4 P S-9

10 Table S6. The Fe leaching concentration during the heterogeneous UVA/Fenton catalytic reactions (the total Fe amount of the added Fe 3 O 4 was 0.3 mmol). samples C (Fe ions) /mg L 1 M (Fe ions) 10 6 /mol percentage of dissolution/% without Fe 3 O 4 < DL < DL < DL Fe 3 O 4 N Fe 3 O 4 S Fe 3 O 4 R Fe 3 O 4 C Fe 3 O 4 O Fe 3 O 4 P S-10

11 Figure S1 HRTEM analysis of the Fe 3 O 4 R particle (a) and (b) and their Fourier transforms images (upper right insets), the lattice d-spacing corresponding to the known {211} and {311}. S-11

12 Figure S2. Fitting results of Fe 2p spectra in the assignment of Fe 2+ and Fe 3+. S-12

13 Figure S3. Fitting results of O 1s spectra. S-13

14 Figure S4. Room temperature magnetic hysteresis loops of the as-obtained Fe 3 O 4 NPs (Inset: magnified view). S-14

15 Figure S5. The kinetics process fitted by pseudo-first-order rate law (AOII: 100 mg L 1, H 2 O 2 : 20 mmol L 1, Catalyst: 0.5 g L 1, 50 ml, ph: 3.0, 25 o C). S-15

16 Figure S6. UV-vis spectral changes for AOII degradation with Fe 3 O 4 NPs by UVA/Fenton process: AOII: 100 mg L 1, H 2 O 2 : 20 mmol L 1, catalyst: 0.5 g L 1, 50 ml, ph: 3.0, 25 o C). S-16

17 Figure S7. The DMPO spin-trapping ESR spectra for hydroxyl radical ( OH) in aqueous solution generated by H 2 O 2 and Fenton systems under UVA irradiation. In situ UVA light irradiation was provided with a mercury lamp λ=365 nm, H 2 O 2 : 20 mmol L 1, Catalyst: 0.5 g L 1, Water: 50 ml, ph: 3.0, 25 o C. S-17

18 Figure S8. The DMPO spin-trapping ESR spectra for superoxide radical (O 2 ) in methanol medium generated by H 2 O 2 and Fenton systems under UVA irradiation. In situ UVA light irradiation was provided with a mercury lamp λ=365 nm, H 2 O 2 : 20 mmol L 1, Catalyst: 0.5 g L 1, Methanol: 50 ml, 25 o C. S-18

19 Figure S9. Comparison of degradation efficiency with and without the scavenger DMSO in reaction solution containing Fe 3 O 4 S (H 2 O 2 : 20 mmol L 1, Catalyst: 0.5 g L 1, C 0(AOII) : 100 mg L 1, DMSO: 100 mmol L 1, 25 o C). Figure S10. Degradation of AOII with the used Fe 3 O 4 S catalyst for four consecutive experiments (H 2 O 2 : 20 mmol L 1, Catalyst: 0.5 g L 1, C 0(AOII) : 100 mg L 1, 50 ml,, 25 o C) S-19

20 Figure S11. X-ray diffraction patterns of the fresh and used Fe 3 O 4 S NPs. Figure S12. SEM images of the used Fe 3 O 4 S NPs S-20