Photo-transformation of graphene oxide in the presence of co-existing metal ions regulated its toxicity to freshwater algae

WATER RESEARCH

卷:176

Article

Zhao, Jian^1,2  Ning, Fangyuan¹  Cao, Xuesong³  Yao, Huan¹  Wang, Zhenyu³  Xing, Baoshan⁴ 

[1] Ocean Univ China, Inst Coastal Environm Pollut Control, Inst Adv Ocean Study, Key Lab Marine Environm & Ecol,Minist Educ, Qingdao 266100, Peoples R China

[2] Qingdao Natl Lab Marine Sci & Technol, Lab Marine Ecol & Environm Sci, Qingdao 266237, Peoples R China

[3] Jiangnan Univ, Sch Environm & Civil Engn, Inst Environm Proc & Pollut Control, Wuxi 214122, Jiangsu, Peoples R China

[4] Univ Massachusetts, Stockbridge Sch Agr, Amherst, MA 01003 USA

关键词: Graphene oxide;    Photo-transformation;    Heavy metal;    Combined toxicity;    Membrane damage;   

DOI  :  10.1016/j.watres.2020.115735

来源: Elsevier

【 摘 要 】

Graphene oxide (GO) sheets are unstable in aqueous environments, and the effect of photo-transformation on GO toxicity to freshwater algae (Chlorella pyrenoidosa) was investigated. Our results demonstrated that GO underwent photo-reduction under 25-day sunlight irradiation, and the transformation was generally completed at Day 8. The toxicological investigation showed that 8-day sunlight irradiation significantly increased growth inhibition of GO (25 mg/L) to algal cells by 11.2%, due to enhanced oxidative stress and stronger membrane damage. Low molecular weight (LMW) species were produced during the 8-day GO transformation, and they were identified as two types of aromatic compounds, which played a crucial role in increasing toxicity. The combined toxicity of GO and Cu2+ ions before and after light irradiation was further investigated. Antagonistic effect was observed between the toxicity of pristine GO and co-existing Cu2+ ions. After co-irradiation of GO and Cu2+ ions for 8 days, their combined toxicity was unexpectedly lower or insignificant in comparison with the treatments of pristine GO, or pristine GO in the presence of Cu2+ ions. Two mechanisms were revealed for this finding: (1) Cu2+ ions suppressed the photo-transformation of GO; (2) the toxicity of free Cu2+ ions was decreased through the adsorption/retention of Cu2+ ions and formation of Cu-based nanoparticles (e.g., Cu2O and Cu2S) on the photo-transformed GO. The provided data are helpful for better understanding the environmental process and risk of GO under natural conditions. (C) 2020 Elsevier Ltd. All rights reserved.

【 授权许可】

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