title: Dissolution Behavior of Silver Nanoparticles and Formation of Secondary Silver Nanoparticles in Municipal Wastewater by Single-Particle ICP-MS.
abstract: Ag nanoparticles (nAg) are used in various consumer products and a significant fraction is eventually discharged with municipal wastewater (WW). In this study we assessed the release of Ag from polyvinylpyrrolidone (PVP)- and citrate-coated 80 nm nAg in aerobic WW effluent and mixed liquor and the related changes in nAg size, using single particle ICP-MS (spICP-MS). The concentration of dissolved (nonparticulate) Ag in WW effluent was 0.89 ± 0.05 ppb at 168 h and was 71% lower than in deionized (DI) water, in batch reactors spiked with 5 × 106PVP-nAg particles/mL (10 μg/L), an environmentally relevant concentration. Dissolved Ag in WW was partly reformed into ∼22 nm nAgxSyby inorganic sulfides and organosulfur dissolved organic carbon (DOC) after 120 h, whereas the parent nAg mean diameter decreased to 65.89 ± 0.9 nm. Reformation of nAgxSyfrom Ag+also occurred in cysteine solutions but not in DI water, or humic and fulvic acid solutions. Dissolution experiments with nAg in WW mixed liquor showed qualitatively similar dissolution trends. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) analyses indicated binding of thiol- and amine-containing DOC as well as inorganic sulfides with nAg. Those WW components, as well as limited dissolved oxygen, decreased dissolution in WW.
authors.affiliation: Department of Civil Engineering, McGill University , Montreal, Quebec, Canada.
authors.forename: Mehrnoosh
authors.initials: M
authors.lastname: Azodi
authors.affiliation: Environment and Climate Change Canada , Gatineau, Quebec, Canada.
authors.forename: Yasir
authors.initials: Y
authors.lastname: Sultan
authors.affiliation: Department of Civil Engineering, McGill University , Montreal, Quebec, Canada.
authors.forename: Subhasis
authors.initials: S
authors.lastname: Ghoshal
mesh_terms: D053768:Metal Nanoparticles / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D012995:Solubility; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D012834:Silver; D062065:Wastewater; D014874:Water Pollutants, Chemical