title: Discovery and characterization of silver sulfide nanoparticles in final sewage sludge products.
abstract: Nanosized silver sulfide (α-Ag(2)S) particles were identified in the final stage sewage sludge materials of a full-scale municipal wastewater treatment plant using analytical high-resolution transmission electron microscopy. The Ag(2)S nanocrystals are in the size range of 5-20 nm with ellipsoidal shape, and they form very small, loosely packed aggregates. Some of the Ag(2)S nanoparticles (NPs) have excess S on the surface of the sulfide minerals under S-rich environments, resulting in a ratio of Ag to S close to 1. Considering the current extensive production of Ag NPs and their widespread use in consumer products, it is likely that they are entering wastewater streams and the treatment facilities that process this water. This study suggests that in a reduced, S-rich environment, such as the sedimentation processes during wastewater treatment, nanosized silver sulfides are being formed. This field-scale study provides for the first time nanoparticle-level information of the Ag(2)S present in sewage sludge products, and further suggests the role of wastewater treatment processes on transformation of Ag nanoparticles and ionic Ag potentially released from them.
authors.affiliation: The Center for NanoBioEarth, Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA. bk74@vt.edu
authors.forename: Bojeong
authors.initials: B
authors.lastname: Kim
authors.forename: Chee-Sung
authors.initials: CS
authors.lastname: Park
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Murayama
authors.forename: Michael F
authors.initials: MF
authors.lastname: Hochella
mesh_terms: D017348:Microscopy, Electron, Scanning Transmission; D053758:Nanoparticles; D012722:Sewage; D018030:Silver Compounds / Q000737:chemistry*
chemical_list: D012722:Sewage; D018030:Silver Compounds; C013251:silver sulfide