The anticipated increases in the use and the resulting releases to the environment of Ag nanoparticles (nAg) necessitates a better understanding of the environmental transformation of nAg to effectively assess and manage environmental risks. Dissolution of Ag NPs is an important environmental transformation process because it releases dissolved Ag into the aquatic environment and alters the size of Ag NPs, both of which can influence the toxicity characteristics of NPs. A signification fraction of nAg used in various products are expected to be released with wastewater (WW) but the factors controlling the dissolution of nAg and the fate of Ag<sup>+</sup> ions released in a complex matrix such as WW are currently poorly understood. Wastewaters contain significant amount of inorganic and organic sulfides, which can influence the rates and extents of dissolution and precipitation of silver. In this study, dissolution of 80 nm PVP–coated nAg NPs in the municipal WW samples collected from a municipal WW treatment plant were studied, at two particle concentrations, 10 and 1000 ppb. Our investigations using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) show that WW organic and inorganic sulfidic constituents, influenced the rates of dissolution, and dissolved Ag reformed into small (~20 nm) sulfidated-nAg over time even under aerobic conditions. Single particle inductively coupled plasma mass spectrometry (SP ICP-MS) was used to determine the mean size and particle size distribution of the NPs and the dissolved silver concentrations to quantify the rate and extent of dissolution of nAg. The WW matrix was inhibitory to the dissolution and the nAg dissolved considerably less (~47%) in WW effluent as compared to DI water under aerobic conditions.

Dissolution behavior of silver nanoparticles and formation of secondary sulfidated silver nanoparticles in municipal wastewater by single particle ICP-MS

253rd National Meeting (2017)

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