Supporting Information Coating Fe 3 O 4 Magnetic Nanoparticles with Humic Acid for High Efficient Removal of Heavy Metals in Water Jing-fu Liu, Zong-shan Zhao, and Gui-bin Jiang* State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco- Environmental Sciences, Chinese Academy of Sciences, P. O. Box 2871, Beijing 185, China. Number of Pages: 1 Number of Table: 1 Number of Figures: 1 S1
Experimental Reagents. All chemicals were of analytical grade obtained from Beijing Chemicals Co. (Beijing, China) otherwise stated, and used without further purification. Ultrapure water (EASY-pure LF, Barnstead International, Dubuque, Iowa USA) was used throughout the experiment. Terrestrial origin humic acid sodium salts were made from Acros organics (lignite, technical, 5-6 as humic acid; Acros Organics, Morris Plains, NJ, USA) and Aldrich (tech., lot. S15539-384, Sigma-Aldrich), respectively. The DOC (measured in a solution prepared by dissolving 2 mg in 2 ml of water and filtrated through.45 µm membrane, with a Phoenix 8 UV-persulfate TOC Analyzer, Tekmar Dohrmann, USA) for Acros humic acid and Aldrich humic acid were 45. % and 35.1%, respectively. Individual Hg(II), Pb(II), Cd(II) and Cu(II) standard solutions were prepared with their chloride except for Pb(II) was prepared with its acetic salts. Characterization of the Bare and Humic Acid Coated Fe 3 O 4 Magnetic Nanoparticles. Transmission electron microscopy (TEM) was carried out with H-75 (Hitachi, Japan). The dissolved organic carbon (DOC) was measured with a Phoenix 8 UV-persulfate TOC Analyzer (Tekmar Dohrmann, USA). UV/Vis absorbance was record on a UV/Vis visible spectrophotometer (U31, Hitachi, Japan). The BET (N 2 ) surface areas, measured with ASAP 2 (Micrometrics instrument Corp., USA), are 62 and 64 m 2 /g for freeze-dried Fe 3 O 4 and Fe 3 O 4 /HA, respectively. The zeta potential of Fe 3 O 4 and Fe 3 O 4 /HA particles were measured at various ph with a Malvern Zetasizer 2 (Malvern Instruments, UK). X-ray photoelectron spectroscopy (XPS) data were obtained with an ESCALab22i- XL electron spectrometer from VG scientific using 3 W AlKα radiations. The base pressure was about 3 1-9 mbar. The binding energies were referenced to C1s line at 284.8ev from adventitious carbon. The particle size in aqueous suspensions was also measured using a Mastersizer 2 laser particle size analyzer (Malvern, UK). S2
Results and Discussion Table S1. Leaching of HA, Fe and Heavy Metals per Total Amount after Re-suspending the Heavy Metal Laden Fe 3 O 4 /HA in Deionized Water for Varied Times. Time (day) Fe (%) TOC (%) Cu (%) Cd (%) Hg (%) Pb (%).5.66 3.5.28.3.18.24 3.16.67.28.29.52.24 5.19.4.28.3.48.22 7.2.32.28.29.47.31 12.21.33.28.29.47.26 S3
Figure S1. Scheme of the removal of heavy metals with the humic acid coated Fe 3 O 4 magnetic nanoparticles..3 Abs.2.1 a c b. 2 3 4 5 Wavelength (nm) Figure S2. UV-Vis spectra of Fe 3 O 4 (a), HA (b) and Fe 3 O 4 /HA (c) S4
5 4 Fe 2P3 (a) KCPS 3 2 O1s 1 N1s C1s 1 8 6 4 2 Binding Energy(eV) 2 (b) 15 O1s C1s KCPS 1 N1s Na(A) 5 Na2s 1 8 6 4 2 Binding Energy (ev) Figure S3. X-ray photoelectron spectroscopy (XPS) of Fe 3 O 4 /HA (a) and HA (b). S5
Zeta Potential (mv) 3 2 1-1 -2-3 2 4 6 8 1 ph Fe3O4/HA Fe3O4 Figure S4. The zeta potentials of the as-prepared Fe 3 O 4 and Fe 3 O 4 /HA at varied ph. Magnetization (emu/g) 1 8 6 4 2-2 -4-6 -8-1 a b -2-1 1 2 Applied Magnetic Field (Oe) Figure S5. Magnetization curves of the as-prepared Fe 3 O 4 (a) and Fe 3 O 4 /HA (b) nanoparticles. S6
Figure S6. TEM images of the as-prepared Fe 3 O 4 /HA. S7
1 8 (a) Intensity 6 4 2 5 1 15 2 25 3 35 4 Diameter (nm) 1 (b) 8 Intensity 6 4 2 5 1 15 2 25 3 35 4 Diameter(nm) Figure S7. Laser particle size analysis of the as-prepared Fe 3 O 4 (a) and Fe 3 O 4 /HA (b) nanoparticles. S8
Removal (%) 1 75 5 25 Removal (%) 97 96 95 94 93 1 2 3 4 5 6 7 8 9 Time (min) Hg Pb Cd Cu 1 2 3 4 5 6 7 8 9 Time (min) Figure S8. Sorption kinetics of heavy metals to the Fe 3 O 4 /HA. In 1 ml of aqueous solution containing.1 mg/l each of Hg(II), Pb(II), Cd(II) and Cu(II) (ph 6.) was added 1 mg of Fe 3 O 4 /HA. Removal (%) 1 9 8 7 6 5 4 3 2 1 Removal (%) 1 98 96 94 92 9 88..1.2.3.4 NaCl (%)..1.2.3.4 NaCl (%) Cu Cd Hg Pb Figure S9. Influence of salinity on the removal of heavy metals by the as-prepared Fe 3 O 4 /HA. In 1 ml of aqueous solutions containing.1 mg/l Hg(II), Pb(II), Cd(II) and Cu(II) adjusted to varied NaCl concentration was added 1 mg of Fe 3 O 4 /HA. S9
Cu Cd 6 6 5 5 q e (mg/g) 4 3 2 q e (mg/g) 4 3 2 1 1 1 2 3 4 5 1 2 3 4 5 C e (mg/l) C e (mg/l) Hg Pb 1 1 75 75 q e (mg/g) 5 q e (mg/g) 5 25 25 1 2 3 4 1 2 3 4 C e (mg/l) C e (mg/l) Figure S1. The adsorption isotherms of the heavy metals with the as-prepared Fe 3 O 4 /HA. S1