Supplementary material

Impacts of Natural Organic Acids on Aquatic Behavior of Graphene Nanoplatelets and Their Induced Algal Toxicity and Antioxidant Capacity

Zhuang Wang1[*], Yucheng Gao1, Se Wang1*, Hao Fang1, Defu Xu1, Fan Zhang1

1 Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (AEET), Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing University of Information Science and Technology, Nanjing 210044, People’s Republic of China

*Corresponding authors:

Zhuang Wang: , Se Wang:

9 Pages

2 Tables

5 Figures


Table S1 Information of the commercial graphene nanoplatelets

Parameters / Details
Thickness / 1-4 nm
Particles size / 2 μm
Specific surface area / 700-800 m²/g
Purity / 91 at.%
Other elements / O < 7 at.%; N < 2 at.%


Fig. S1 TEM image of the studied graphene nanoplatelets

Fig. S2 Zeta potential measurements of the graphene nanoplatelets at various

pH, ranging from 4.1 to 10.0, in the algae growth medium


Table S2 pKa values of the LOA molecules

Name / pKa (298 K)
Experimental
Benzoic acid / 4.20 a
Gallic acid / 4.4, 8.6, 11.2, 12 b

a Braude and Nachod (1955).

b Sandmann et al. (1985).

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Fig. S3 Hydrodynamic size (A) and zeta potential (B) of graphene nanoplatelets (GNPs) at 1 mg/L of suspensions without and with dimethylsulfoxide (DMSO) of 0.4 v/v % in the algae culture medium after stirring for 24 h at room temperature to equilibrate. Values expressed as mean ± standard deviation (n = 3)


Fig. S4 Inhibition effects of dimethylsulfoxide (DMSO) of 0.4 v/v % in the test medium and the test control prepared at pH 6.5

Fig. S5 Growth inhibition rate of S. obliquus exposed to the graphene nanoplatelets (GNPs) as a function of hydrodynamic diameter (A and B) and zeta potential (C and D) of the GNPs obtained after adding initial particle concentrations of 1 and 5 mg/L GNPs into three different concentrations (1, 10, and 40 mg/L) of benzoic acid (BA) (A and C) and gallic acid (GA) (B and D).

References

Braude, E.A., Nachod, F.C. (Eds.), 1955. Determination of Organic Structures by Physical Methods. Academic Press, New York.

Sandmann, B.J., Chien, M.H., Sandmann, R.A., 1985. Stability constants of calcium, magnesium and zinc gallate using a divalent ion-selective electrode. Analytical Letters 18, 149–159.

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[*] Corresponding authors. Tel./fax: +86 25 58731090 (Z. Wang and S. Wang).

E-mail addresses: (Z. Wang); (S. Wang).