title: Nanoparticles of WC-Co, WC, Co and Cu of relevance for traffic wear particles - Particle stability and reactivity in synthetic surface water and influence of humic matter.
abstract: Studded tyres made of tungsten carbide cobalt (WC-Co) are in the Northern countries commonly used during the winter time. Tungsten (W)-containing nano- and micron-sized particles have been detected close to busy roads in several European countries. Other typical traffic wear particles consist of copper (Cu). The aims of this study were to investigate particle stability and transformation/dissolution properties of nanoparticles (NPs) of WC-Co compared with NPs of tungsten carbide (WC), cobalt (Co), and Cu. Their physicochemical characteristics (primarily surface oxide and charge) are compared with their extent of sedimentation and metal release in synthetic surface water (SW) with and without two different model organic molecules, 2,3- and 3,4-dihydroxybenzoic acid (DHBA) mimicking certain sorption sites of humic substances, for time periods up to 22 days. The WC-Co NPs possessed a higher electrochemical and chemical reactivity in SW with and without DHBA molecules as compared with NPs of WC, Co, and Cu. Co was completely released from the WC-Co NPs within a few hours of exposure, although it remained adsorbed/bonded to the particle surface and enabled the adsorption of negatively charged DHBA molecules, in contrast with the WC NPs (no adsorption of DHBA). The DHBA molecules were found to rapidly adsorb on the Co and Cu NPs. The sedimentation of the WC and WC-Co NPs was not influenced by the presence of the 2,3- or 3,4-DHBA molecules. A slight influence (slower sedimentation) was observed for the Co NPs, and a strong influence (slower sedimentation) was observed for the Cu NPs in SW with 2,3-DHBA compared with SW alone. The extent of metal release increased in the order: WC < Cu < Co < WC-Co NPs. All NPs released more than 1 wt-% of their metal total mass. The release from the Cu NPs was most influenced by the presence of DHBA molecules.
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Sweden; Unit of Work Environment Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Sweden. Electronic address: yolanda@kth.se.
authors.forename: Yolanda S
authors.initials: YS
authors.lastname: Hedberg
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Sweden. Electronic address: jhed@kth.se.
authors.forename: Jonas F
authors.initials: JF
authors.lastname: Hedberg
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Sweden. Electronic address: sarais@kth.se.
authors.forename: Sara
authors.initials: S
authors.lastname: Isaksson
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Sweden. Electronic address: nanxuan@kth.se.
authors.forename: Nanxuan
authors.initials: N
authors.lastname: Mei
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Sweden; SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, Sweden. Electronic address: blev@kth.se.
authors.forename: Eva
authors.initials: E
authors.lastname: Blomberg
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Technology, Applied Physical Chemistry, Sweden. Electronic address: wold@kth.se.
authors.forename: Susanna
authors.initials: S
authors.lastname: Wold
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, Sweden. Electronic address: ingero@kth.se.
authors.forename: Inger
authors.initials: I
authors.lastname: Odnevall Wallinder
mesh_terms: D001336:Automobiles; D003035:Cobalt / Q000032:analysis*; D003300:Copper / Q000032:analysis*; D006812:Humic Substances; D053758:Nanoparticles / Q000032:analysis* / Q000737:chemistry*; D010316:Particle Size; D012408:Rubber / Q000737:chemistry*; D017973:Tungsten Compounds / Q000032:analysis*; D014867:Water / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D017973:Tungsten Compounds; D014867:Water; C002802:tungsten carbide; D003035:Cobalt; D003300:Copper; D012408:Rubber
keywords: Cobalt; Copper; Metal release; Nanoparticles; Tungsten