title: Release of (14)C-labelled carbon nanotubes from polycarbonate composites.
abstract: Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs ((14)C-CNT) for polycarbonate polymer nanocomposites with 1 wt% (14)C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m(2), whereas only 0.8 mg CNT/m(2) were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites.
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rhiem
authors.affiliation: Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
authors.forename: Anne-Kathrin
authors.initials: AK
authors.lastname: Barthel
authors.affiliation: BAuA - Federal Institute for Occupational Safety and Health, Nöldnerstr. 40-42, 10317 Berlin, Germany.
authors.forename: Asmus
authors.initials: A
authors.lastname: Meyer-Plath
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hennig
authors.affiliation: Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Wachtendorf
authors.affiliation: Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
authors.forename: Heinz
authors.initials: H
authors.lastname: Sturm
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schäffer
authors.affiliation: Institute for Environmental Research (Biology V), RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany. Electronic address: hanna.maes@bio5.rwth-aachen.de.
authors.forename: Hanna M
authors.initials: HM
authors.lastname: Maes
mesh_terms: D002247:Carbon Isotopes; D002254:Carbonates / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011076:Polycarboxylate Cement / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011851:Radioactivity; D012037:Refuse Disposal / Q000379:methods*; D013055:Spectrophotometry, Infrared; D013472:Sunlight
chemical_list: D002247:Carbon Isotopes; D002254:Carbonates; D004785:Environmental Pollutants; D037742:Nanotubes, Carbon; D011076:Polycarboxylate Cement; D011108:Polymers; C005506:polycarbonate
keywords: Carbon nanotubes; Nanocomposites; Quantification; Release; Weathering