title: Effect of natural organic matter on cerium dioxide nanoparticles settling in model fresh water.
abstract: The ecological risk assessment of chemicals including nanoparticles is based on the determination of adverse effects on organisms and on the environmental concentrations to which biota are exposed. The aim of this work was to better understand the behavior of nanoparticles in the environment, with the ultimate goal of predicting future exposure concentrations in water. We measured the concentrations and particle size distributions of CeO(2) nanoparticles in algae growth medium and deionized water in the presence of various concentrations and two types of natural organic matter (NOM). The presence of natural organic matter stabilizes the CeO(2) nanoparticles in suspension. In presence of NOM, up to 88% of the initially added CeO(2) nanoparticles remained suspended in deionized water and 41% in algae growth medium after 12d of settling. The adsorbed organic matter decreases the zeta potential from about -15 mV to -55 mV. This reduces aggregation by increased electrostatic repulsion. The particle diameter, pH, electric conductivity and NOM content shows significant correlation with the fraction of CeO(2) nanoparticles remaining in suspension.
authors: Department of Environmental Science, Radboud University Nijmegen, Institute for Wetland and Water Research, PO Box 9010, 6500 GL Nijmegen, The Netherlands. joris.quik@rivm.nl
authors: Joris T K
authors: JT
authors: Quik
authors: Iseult
authors: I
authors: Lynch
authors: Karen
authors: K
authors: Van Hoecke
authors: Cornelis J H
authors: CJ
authors: Miermans
authors: Karel A C
authors: KA
authors: De Schamphelaere
authors: Colin R
authors: CR
authors: Janssen
authors: Kenneth A
authors: KA
authors: Dawson
authors: Martien A Cohen
authors: MA
authors: Stuart
authors: Dik
authors: D
authors: Van De Meent
mesh_terms: D002563:Cerium / Q000737:chemistry*; D005618:Fresh Water / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D010316:Particle Size; D014873:Water Pollutants / Q000737:chemistry*
chemical_list: D009930:Organic Chemicals; D014873:Water Pollutants; D002563:Cerium; C030583:ceric oxide