title: Sorption kinetics and equilibrium of the herbicide diuron to carbon nanotubes or soot in absence and presence of algae.
abstract: Carbon nanotubes (CNT) are strong sorbents for organic micropollutants, but changing environmental conditions may alter the distribution and bioavailability of the sorbed substances. Therefore, we investigated the effect of green algae (Chlorella vulgaris) on sorption of a model pollutant (diuron, synonyms: 3-(3,4-Dichlorophenyl)-1,1-dimethylurea, DCMU) to CNT (multi-walled purified, industrial grade, pristine, and oxidized; reference material: Diesel soot). In absence of algae, diuron sorption to CNT was fast, strong, and nonlinear (Freundlich coefficients: 10(5.79)-10(6.24) μg/kgCNT·(μg/L)(-n) and 0.62-0.70 for KF and n, respectively). Adding algae to equilibrated diuron-CNT mixtures led to 15-20% (median) diuron re-dissolution. The relatively high amorphous carbon content slowed down ad-/desorption to/from the high energy sorption sites for both industrial grade CNT and soot. The results suggest that diuron binds readily, but - particularly in presence of algae - partially reversibly to CNT, which is of relevance for environmental exposure and risk assessment.
authors.affiliation: Empa - Swiss Federal Laboratories for Materials Science and Technology, CH-9014 St. Gallen, Switzerland; Agroscope, Institute for Sustainability Sciences ISS, CH-8046 Zurich, Switzerland.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Schwab
authors.affiliation: Agroscope, Institute for Sustainability Sciences ISS, CH-8046 Zurich, Switzerland.
authors.forename: Louise
authors.initials: L
authors.lastname: Camenzuli
authors.affiliation: Federal Office for Agriculture FOAG, CH-3003 Bern, Switzerland.
authors.forename: Katja
authors.initials: K
authors.lastname: Knauer
authors.affiliation: Empa - Swiss Federal Laboratories for Materials Science and Technology, CH-9014 St. Gallen, Switzerland.
authors.forename: Bernd
authors.initials: B
authors.lastname: Nowack
authors.affiliation: EPFL - Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Magrez
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Duebendorf, Switzerland.
authors.forename: Laura
authors.initials: L
authors.lastname: Sigg
authors.affiliation: Agroscope, Institute for Sustainability Sciences ISS, CH-8046 Zurich, Switzerland. Electronic address: thomas.bucheli@agroscope.admin.ch.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Bucheli
mesh_terms: D000327:Adsorption; D002708:Chlorella / Q000187:drug effects / Q000502:physiology; D000460:Chlorophyta / Q000187:drug effects / Q000502:physiology*; D004237:Diuron / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D037742:Nanotubes, Carbon / Q000737:chemistry*; D053260:Soot / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D006540:Herbicides; D037742:Nanotubes, Carbon; D053260:Soot; D014874:Water Pollutants, Chemical; D004237:Diuron
keywords: Bioavailability; Black carbon; Engineered nanomaterials; Nanoparticles; Sorption kinetics