title: Sulfidation processes of PVP-coated silver nanoparticles in aqueous solution: impact on dissolution rate.
abstract: Despite the increasing use of silver nanoparticles (Ag-NPs) in nanotechnology and their toxicity to invertebrates, the transformations and fate of Ag-NPs in the environment are poorly understood. This work focuses on the sulfidation processes of PVP-coated Ag-NPs, one of the most likely corrosion phenomena that may happen in the environment. The sulfur to Ag-NPs ratio was varied in order to control the extent of Ag-NPs transformation to silver sulfide (Ag₂S). A combination of synchrotron-based X-ray Diffraction (XRD) and Extended X-ray Absorption Fine Structure spectroscopy shows the increasing formation of Ag₂S with an increasing sulfur to Ag-NPs ratio. TEM observations show that Ag₂S forms nanobridges between the Ag-NPs leading to chain-like structures. In addition, sulfidation strongly affects surface properties of the Ag-NPs in terms of surface charge and dissolution rate. Both may affect the reactivity, transport, and toxicity of Ag-NPs in soils. In particular, the decrease of dissolution rate as a function of sulfide exposure may strongly limit Ag-NPs toxicity since released Ag⁺ ions are known to be a major factor in the toxicity of Ag-NPs.
authors: Surface and Aqueous Geochemistry Group, Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305-2115, USA. clevard@stanford.edu
authors: Clément
authors: C
authors: Levard
authors: Brian C
authors: BC
authors: Reinsch
authors: F Marc
authors: FM
authors: Michel
authors: Camella
authors: C
authors: Oumahi
authors: Gregory V
authors: GV
authors: Lowry
authors: Gordon E
authors: GE
authors: Brown