title: Residence time effects on phase transformation of nanosilver in reduced soils.
abstract: Residence time effects on phase transformation of silver nanoparticles (AgNPs) (15-50 nm, with and without polyvinylpyrrolidone (PVP) coating) were investigated in reducing soils using experimental geochemistry and synchrotron-based x-ray techniques. After 30 days of anaerobic incubation, a substantial fraction of PVP-coated AgNPs (15 nm) were transformed into Ag₂S and or humic acid (HA) complexed Ag(I), whereas only the HA fraction was dominant in uncoated AgNPs (50 nm). Several investigations recently reported that sulfidation of AgNPs to Ag₂S was the predominant mechanism controlling the fate of AgNP in soil-water environments. However, this investigation showed each AgNP underwent particle-specific chemical transformations to different end compounds after 30 days. Considering the small contribution of Ag(I) dissolution from all AgNPs (less than 5%), we concluded that changes in solid-state chemical speciation of sorbed AgNPs was promoted by particle-specific interactions of NPs in soil chemical constituents, suggesting a critical role of soil absorbents in predicting the fate of AgNPs in terrestrial environments.
authors.affiliation: Department of Biological and Environmental Sciences, Georgia College & State University, Campus Box 081, Milledgeville, GA, 31061, USA.
authors.forename: Allison
authors.initials: A
authors.lastname: Rick VandeVoort
authors.forename: Ryan
authors.initials: R
authors.lastname: Tappero
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
mesh_terms: D004577:Electron Probe Microanalysis; D006812:Humic Substances / Q000032:analysis; D053768:Metal Nanoparticles / Q000032:analysis* / Q000737:chemistry; D011205:Povidone / Q000737:chemistry; D012834:Silver / Q000032:analysis* / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D017356:Synchrotrons; D013997:Time Factors
chemical_list: D006812:Humic Substances; D012987:Soil; D012989:Soil Pollutants; D012834:Silver; D011205:Povidone