Dissolved organic matter-mediated reduction of ionic Au(III) to elemental Au nanoparticles and their growth to visible granules |
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| Institution: | 1. Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;2. State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;3. University of Chinese Academy of Sciences, Beijing 100049, China;4. School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China;5. Shimadzu China Innovation Center, Shimadzu (China) Co. LTD, Beijing 100020, China;6. Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States |
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| Abstract: | The biogeochemical transformation of gold (Au), i.e. its dissolution and re-precipitation, is critical in supergene transport of Au and formation of Au granules. Besides biogenic reduction, the formation Au granules can also be driven by chemical processes. Previous studies have showed the formation of Au nanoparticles (AuNPs) from ionic Au(III) can be mediated by dissolved organic matter under sunlight. In this letter, we further demonstrated that these AuNPs can further slowly (in years) grow into visible Au granules. Different sized nano-flower and fractal dendrite-like branched gold structures (from tens of nanometres to over 100 μm) were observed in the Au granule sample. This growth of AuNPs into visible Au granules may play a critical role in the supergene mineralization and enrichment of secondary Au and drive the biogeochemical cycle of Au. |
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| Keywords: | Gold granule Gold nanoparticle Dissolved organic matter Photochemical reduction Mineralization |
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