Removal of Microcystis aeruginosa by using nano-Fe3O4 particles as a coagulant aid
Bo Zhang1, Dan Jiang1, Xiaochen Juo1, Yiliang He1*, Ong Choon Nam2, Yongpeng Xu3,
Amrita Pal2
1
School of Environmental Science & Engineering, Shanghai Jiaotong University
NUS Environmental Research Institute, National University of Singapore, Singapore
3
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin
150090, China
2
S1. The preparation of nano-Fe3O4.
The nano-Fe3O4 can 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,
poured into conical flask, 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 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-Fe3O4 in the lab was analyzed
by X-ray diffraction (XRD), as shown in Fig. S1a. This curve represents the typical spinelstructured 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 190629) (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 sizes by TEM analysis. The average
particle size is roughly 100 nm.
120
a
Intensity (Counts)
100
80
60
40
20
0
20
40
b
60
80
c
Fig S1. a. Characterization of Nano-Fe3O4; b. XRD analysis; 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. aeruginosa was
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.
Removal efficiency (%)
100
80
60
PACl
PACl:Nano-Fe3O4=8:1
40
PACl:Nano-Fe3O4=4:1
PACl:Nano-Fe3O4=1:1
20
PACl:Nano-Fe3O4=4:3
0
0
10
20
30
40
50
PACl concentraion (mg/L)
Fig.S2. Effect of PACl and nano-Fe3O4 dose on removal efficiency of M. aeruginosa. M.
aeruginosa concentration is 106 pcs/mL; Sedimentation time is 60 min
Fig.S3. Thickness of precipitation layer under different conditions. M. aeruginosa
concentration is 106 pcs/mL