Removal of Microcystisaeruginosa by using nano-Fe3O4 particles as a coagulant aid
Bo Zhang1, Dan Jiang1, Xiaochen Juo1, Yiliang He1*, Ong Choon Nam2, Yongpeng Xu3 , Amrita Pal2
1School of Environmental Science & Engineering, Shanghai Jiaotong University
2NUS EnvironmentalRresearch Institute, National University of Singapore, Singapore
3State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
S1. The preparation ofnano-Fe3O4.
The nano-Fe3O4can be generated by using ferrous ion and ferric ion in alkaline condition. The reaction equation is shown as follows:
2FeC13·6H2O+FeCl2·4H2O+8NaOH=Fe3O4+8NaCl+20H2O
8g of FeC13·6H2O and 4g of FeCl2·4H2O were dissolved in 100 ml of deionized water, was poured into conical flask, was and heated in the water bath at the temperature of 40℃. After the FeC13 and FeCl2 were completely dissolved, NaOH solution of 5 mol/L was quickly added with violent vigorous stirring, and then 100 g/L of polyethyleneglycol solution（PEG-600）was dropwise added after color change of the solution. The mixture was stirred for 15 minutes in nitrogen, and was kept for 30 minutes in water bath through nitrogen at the temperature of 80℃. Finally, the obtained black fluid was cooled to room temperature. Centrifugal washing was performed twice by first using deionized water, and then by using absolute ethyl alcohol. The obtained black precipitate was put into vacuum drying oven for drying for 24 hours at the temperature of 65℃, and then ground by using mortar. The obtained powder was put into sealed bottle with nitrogen protection for subsequent use.
S2. Characterization of nano- Fe3O4
Compositions, internal structure or form of prepared nano-Fe3O4in the lab was analyzed by X-ray diffraction (XRD), as shown in Fig. S1a. This curve is represents the typical spinel-structured magnetic Fe3O4 particles. The diffraction peak appears at 2 theta of 18.3°, 30.1°, 35.4°, 37.2°, 43.1°, 53.3°, 56.9°, and 62.5°, which is typically the crystal surface structure of (1 1 1 ), (2 2 0), (3 1 1 ), (2 2 2 ), (4 0 0 ), (4 2 2 ), (5 1 1 ), and (4 4 0 ) of Fe3O4 (JCPDS 19-0629)(Qu et al., , Zhi et al., 2006, Shen et al. 2009). As is shown in Fig. S1b, the prepared magnetic Fe3O4 particles are aggregated in even particle sizesby TEM analysis. The average particle size is roughly 100 nm.
Fig S1. a. Characterization of Nano-Fe3O4.;ab.XRD analysis; b.c. TEM analysis
S3. The effect of the ratio of PACl to Nano-Fe3O4 on the removal efficiency of M. aeruginosa was evaluated, as indicated in Fig.S2. The removal efficiency of M. aeruginosawas improved with the increased concentrations of PACl dosage in the presence of nano-Fe3O4, and a dosage of 20 mg/L yielded more than 90% of removal efficiency.
Fig.S2. Effect of PACl and Nanonano- Fe3O4dose on removal efficiency of M. aeruginosa. M. aeruginosaconcentration is 106 pcs/mL; Sedimentation time of is 60 min
Fig.S3. Thickness of precipitation layer under different conditions. M. aeruginosaconcentration is 106 pcs/mL