Details

Autor(en) / Beteiligte

• Metreveli, George
• David, Jan
• Schneider, Reinhard
• Kurtz, Sandra
• Schaumann, Gabriele E.

Titel

Morphology, structure, and composition of sulfidized silver nanoparticles and their aggregation dynamics in river water

Ist Teil von

• The Science of the total environment, 2020-10, Vol.739, p.139989-139989, Article 139989

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2020

Quelle

ScienceDirect

Beschreibungen/Notizen

• The sulfidized form represents an environmentally relevant transformation state of silver nanoparticles (Ag-NPs) released into natural systems via wastewater route. However, the detailed characterization of sulfidized silver nanoparticles (S-Ag-NPs) is missing and their colloidal stability in aquatic systems is only insufficiently studied. The aim of this study was to systematically evaluate the surface properties, morphology, structure, composition, as well as aggregation dynamics of S-Ag-NPs in synthetic and natural river water. The S-Ag-NPs were prepared by sulfidation of citrate-coated silver nanoparticles (Cit-Ag-NPs). The sulfidation of Ag-NPs was accompanied by the formation of fiber-like Ag2S nano-bridges, Ag0-Ag2S core-shell structures, and hollow regions. In contrast to the published literature, the nano-bridges were thinner (2–9 nm) and longer (up to 60 nm), they formed at higher S2−/Ag molar ratio (2.041), and the formation of the core-shell structures was observed even in the absence of natural organic matter (NOM). Furthermore, we observed selective sulfidation of nanoparticles which can induce the hot spots for the release of toxic Ag+ ions. The critical coagulation concentration (CCC) of Ca2+ determined for S-Ag-NPs in reconstituted river water was 2.47 ± 0.23 mmol/L and thus higher than the CCC obtained for Cit-Ag-NPs in our earlier study revealing higher colloidal stability of S-Ag-NPs. In natural river water, S-Ag-NPs were also colloidally more stable compared to the Cit-Ag-NPs. Furthermore, the stabilizing effect of NOM was much higher for S-Ag-NPs than for Cit-Ag-NPs. For S-Ag-NPs stabilized by a low amount of citrate, we expect longer residence times in the water phase of rivers and thus higher risk for aquatic organisms. In contrast to this, the pristine Cit-Ag-NPs are expected to be accumulated faster in the sediments representing higher risk for benthic organisms. This study contributes to better understanding of environmental fate and effects of Ag-NPs released via wastewater route. [Display omitted] •Formation of thin and long silver sulfide nano-bridges for sulfidized Ag-NPs.•Nano-bridges are formed at a higher S2−/Ag molar ratio than reported in literature.•Ag0-Ag2S core-shell structures of sulfidized Ag-NPs are formed in absence of NOM.•Sulfidation enhances colloidal stability of citrate-coated Ag-NPs in river water.•Stabilizing effect of NOM is higher for sulfidized than for citrate-coated Ag-NPs.