Wei Zhang - Fullerene nanoparticles exhibit greater retention in freshwater sediment than in model porous media

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  Publication Details (including relevant citation   information): Zhang, Wei, Isaacson, Carl W.,   Rattanaudompol, U-sa, Powell, Tremaine B., Bouchard, Dermont,   Water Research, 2012, 46 (9),   pp 2992-3004

  Abstract: Increasing production and use of   fullerene-based nanomaterials underscore the need to determine   their mobility in environmental transport pathways and potential   ecological exposures. This study investigated the transport of   two fullerenes (i.e., aqu/C60 and water-soluble C60 pyrrolidine   tris-acid [C60 PTA]) in columns packed with model porous media   (Iota quartz and Ottawa sand) and a sediment from Call’s creek   under saturated and unsaturated steady-state flows. The   fullerenes had the least retention in Iota quartz, and the   greatest retention in the sediment at near neutral pH,   correlating with the degree of grain surface chemical   heterogeneity (e.g., amorphous Al hydroxides concentration   increasing in the order of Iota quartz < Ottawa sand <   sediment). Surface roughness was elucidated as another important   factor responsible for the greatest fullerene retention in the   sediment. In accordance with the XDLVO energy calculations, C60   PTA was less retained than aqu/C60 at near neutral pH, due to its   greater hydrophilicity measured by tolune–water partition   coefficient, as well as smaller particle sizes revealed by atomic   force microscopy. Fullerene retention exhibited a strong   dependency on solution pH that could be explained partly by the   pH-dependent surface charge of fullerenes and grain surface, and   partly by increased hydrophobicity of C60 PTA when solution pH   approaches its isoelectric point (IEP). Finally, fullerene   retention was enhanced in unsaturated media, implying that   fullerenes may be more attenuated in the vadose zone than in   groundwater.

  Address (URL): http://www.sciencedirect.com/science/article/pii/S0043135412001534