Get access
Advertisement

Natural colloids are the dominant factor in the sedimentation of nanoparticles

Authors

  • Joris T.K. Quik,

    Corresponding author
    1. Institute for Wetland and Water Research, Department of Environmental Science, Radboud University Nijmegen, Nijmegen, The Netherlands
    2. Laboratory for Ecological Risk Assessment, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
    • Institute for Wetland and Water Research, Department of Environmental Science, Radboud University Nijmegen, Nijmegen, The Netherlands.
    Search for more papers by this author
  • Martien Cohen Stuart,

    1. Laboratory of Physical Chemistry and Colloid Science, Wageningen University and Research Centre, Wageningen, The Netherlands
    Search for more papers by this author
  • Marja Wouterse,

    1. Laboratory for Ecological Risk Assessment, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
    Search for more papers by this author
  • Willie Peijnenburg,

    1. Laboratory for Ecological Risk Assessment, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
    2. Institute of Environmental Sciences, Faculty of Science, Leiden University, Leiden, The Netherlands
    Search for more papers by this author
  • A. Jan Hendriks,

    1. Institute for Wetland and Water Research, Department of Environmental Science, Radboud University Nijmegen, Nijmegen, The Netherlands
    Search for more papers by this author
  • Dik van de Meent

    1. Institute for Wetland and Water Research, Department of Environmental Science, Radboud University Nijmegen, Nijmegen, The Netherlands
    2. Laboratory for Ecological Risk Assessment, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
    Search for more papers by this author

Abstract

Estimating the environmental exposure to manufactured nanomaterials is part of risk assessment. Because nanoparticles aggregate with each other (homoaggregation) and with other particles (heteroaggregation), the main route of the removal of most nanoparticles from water is aggregation, followed by sedimentation. The authors used water samples from two rivers in Europe, the Rhine and the Meuse. To distinguish between small (mainly natural organic matter [NOM]) particles and the remainder of the natural colloids present, both filtered and unfiltered river water was used to prepare the particle suspensions. The results show that the removal of nanoparticles from natural river water follows first-order kinetics toward a residual concentration. This was measured in river water with less than 1 mg L−1 CeO2 nanoparticles. The authors inferred that the heteroaggregation with or deposition onto the solid fraction of natural colloids was the main mechanism causing sedimentation in relation to homoaggregation. In contrast, the NOM fraction in filtered river water stabilized the residual nanoparticles against further sedimentation for up to 12 d. In 10 mg L−1 and 100 mg L−1 CeO2 nanoparticle suspensions, homoaggregation is likely the main mechanism leading to sedimentation. The proposed model could form the basis for improved exposure assessment for nanomaterials. Environ. Toxicol. Chem. 2012; 31: 1019–1022. © 2012 SETAC

Get access to the full text of this article

Ancillary