H13P-03
Transport of Silver Nanoparticles in Unsaturated Sand

Monday, 14 December 2015: 14:10
3016 (Moscone West)
Samuel Kwame Kumahor1, Pavel Hron2, George Metreveli3, Gabriele E. Schaumann3, Sondra Klitzke4 and Hans-Joerg Vogel1, (1)Helmholtz Centre for Environmental Research UFZ Halle, Halle, Germany, (2)University of Heidelberg, Interdisciplinary Center for Scientific Computing, Heidelberg, Germany, (3)Universität Koblenz-Landau, Institute for Environmental Sciences, Group of Environmental and Soil Chemistry, Landau, Germany, (4)Technische Universität Berlin, Institute for Ecology, Department of Soil Science, Berlin, Germany
Abstract:
Transport of citrate-coated Ag nanoparticles in the presence of a monovalent cation was compared with “soil-aged” Ag nanoparticles in the presence of both monovalent and multivalent cations using experimental breakthrough curves and numerical modeling. We integrated information on hydraulic state variables measured during transport, optimal parameters obtained from a numerical solution of a convection dispersion reaction model, structure of the flow field derived from morphological analysis and a classical DLVO model extended for hydrophobic interaction to understand the governing transport dynamics. The citrate-coated Ag NP were relatively more mobile compared to the “soil-aged” Ag nanoparticles explained by the differences in solution chemistry. Two processes are peculiar to both citrate-coated and “soil-aged” Ag nanoparticles: retardation and irreversible straining attributed to the air-water and solid-water interfaces respectively. However, the retardation seems to be less pronounced for the “soil-aged” Ag nanoparicles which could be explained by the differences in nanoparticle properties. As an additional phenomenon, cation brigding complexation is suggested for the “soil-aged” Ag nanoparticles due to the presence of multivalent cations. We suggest coupled physical and chemical processes during transport which could be fairly well described by the proposed convection-dispersion-reaction model.