Inter-transformation between silver nanoparticles and Ag(+)induced by humic acid under light or dark conditions

文献类型： 外文期刊

第一作者： Liu, Yujia

作者： Liu, Yujia;Li, Chao;Wu, Haiyong;Liu, Yujia;Luo, Si;Wang, Xi;Zhang, Qingmei

作者机构：

关键词： AgNPs; Reduction; Oxidation; Natural organic matter; Sunlight

期刊名称：ECOTOXICOLOGY （ 影响因子：2.823； 五年影响因子：2.958 ）

ISSN： 0963-9292

年卷期：

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收录情况： SCI

摘要： The fate and toxicity of silver nanoparticles (AgNPs) and ions in water bodies is largely determined by the natural organic matter (NOM)-mediated redox cycling. However, the process of NOM-mediated redox cycling in the day/night cycles remains elusive. In this study, the inter-transformation between AgNPs and Ag(+)ion caused by humic acid (HA) was investigated under controlled light and dark conditions. It was shown that HA induced the reduction of Ag(+)into AgNPs in simulated sunlight, and also oxidize AgNPs to release Ag(+)in darkness. Kinetics data demonstrated that the rates of AgNPs formation and dissolution increased along with the increment of HA concentrations. Along with the pH increase, the reduction of Ag(+)accelerated, but the oxidative dissolution of AgNPs was inhibited. In day-night cycles, the AgNPs and Ag(+)concentrations exhibited similar wave-shaped change curves. The peaks of AgNPs and Ag(+)ion appeared at 7 p.m. and 7 a.m., respectively. The toxicity of AgNPs/Ag(+)toEscherichia coliwas determined primarily by the concentration of dissolved Ag+, but also affected by the particle-specific toxicity. The dual role of HA implied that previous reports about the photo-reduction of Ag(+)to AgNPs by NOM should be reconsidered, and the oxidizability of HA in darkness strongly affect the transformation and toxicity of AgNPs in water.

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