Role of graphene oxide in mitigated toxicity of heavy metal ions on Daphnia magna.

Lingfeng Ni,Yi Li

doi:10.1039/c8ra09135h

Abstract

Graphene oxide (GO) is increasingly used and inevitably released into aquatic environments, facilitating its interaction with traditional pollutants such as heavy metal ions. However, the potential effect of GO on the toxicity of heavy metal ions to aquatic animals is unknown. This work aims to assess the toxicity of heavy metal ions (Cu(ii), Cd(ii), and Zn(ii)) on Daphnia magna (D. magna) in the presence of GO. GO nanoparticles remarkably reduced the concentrations of heavy metal ions by adsorption and decreased the metal accumulation in D. magna. The maximum desorption rate of heavy metal ions from metal-adsorbed GO was below 5%. At pH 7.8, with addition of 2 mg L−1 GO, the 72 h median lethal concentration (LC50) values of Cu(ii), Cd(ii), and Zn(ii) were increased from 14.3, 38, and 780 μg L−1 to 36.6, 72, and 1010 μg L−1, respectively. The analyses of oxidative stress indicators suggested that the oxidative damage to D. magna by heavy metal ions was reduced after addition of GO at pH 7.8. Moreover, a higher pH level in the growing range (6.5 to 8.5) of D. magna led to weaker toxicity of metal ions with GO addition due to more adsorption and less bioaccumulation. The results revealed the role of GO nanoparticles in the mitigated toxicity of heavy metal ions in the aquatic environment.

Highlights

Since the rst isolation in 2004,1 graphene and its derivatives have brought tremendous improvement and development in diverse elds, such as nanoelectronics, catalysis and nanomedicine due to their exceptional mechanical, electronic, optical and catalytic properties.[2,3,4] As an important intermediate product, graphene oxide (GO) could be used to directly produce graphene-based composites, resulting in its mass usage in the graphene industry.[5]
We examined the potential effects of GO on the biotoxicity of heavy metal ions to D. magna, a sensitive and standard Crustacea used in ecotoxicity experiments
The TEM image of the dispersion morphology and nanostructure of GO nanoparticles in reaction medium is shown in Fig. S1.† Layered GO nanosheets with few wrinkles were observed and GO nanoparticles were highly dispersed in reaction medium a er ultrasonication

Summary

Introduction

Since the rst isolation in 2004,1 graphene and its derivatives have brought tremendous improvement and development in diverse elds, such as nanoelectronics, catalysis and nanomedicine due to their exceptional mechanical, electronic, optical and catalytic properties.[2,3,4] As an important intermediate product, graphene oxide (GO) could be used to directly produce graphene-based composites, resulting in its mass usage in the graphene industry.[5]. The 48 h median lethal concentration (LC50) of GO

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