title: Hydrophobic interactions increase attachment of gum Arabic- and PVP-coated Ag nanoparticles to hydrophobic surfaces.
abstract: A fundamental understanding of attachment of surface-coated nanoparticles (NPs) is essential to predict the distribution and potential risks of NPs in the environment. Column deposition studies were used to examine the effect of surface-coating hydrophobicity on NP attachment to collector surfaces in mixtures with varying ratios of octadecylichlorosilane (OTS)-coated (hydrophobic) glass beads and clean silica (hydrophilic) glass beads. Silver nanoparticles (AgNPs) coated with organic coatings of varying hydrophobicity, including citrate, polyvinylpyrrolidone (PVP), and gum arabic (GA), were used. The attachment efficiencies of GA and PVP AgNPs increased by 2- and 4-fold, respectively, for OTS-coated glass beads compared to clean glass beads. Citrate AgNPs showed no substantial change in attachment efficiency for hydrophobic compared to hydrophilic surfaces. The attachment efficiency of PVP-, GA-, and citrate-coated AgNPs to hydrophobic collector surfaces correlated with the relative hydrophobicity of the coatings. The differences in the observed attachment efficiencies among AgNPs could not be explained by classical DLVO, suggesting that hydrophobic interactions between AgNPs and OTS-coated glass beads were responsible for the increase in attachment of surface-coated AgNPs with greater hydrophobicity. This study indicates that the overall attachment efficiency of AgNPs will be influenced by the hydrophobicity of the NP coating and the fraction of hydrophobic surfaces in the environment.
authors.affiliation: Center for Environmental Implications of Nanotechnology (CEINT) and Department of Civil & Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Jee Eun
authors.initials: JE
authors.lastname: Song
authors.forename: Tanapon
authors.initials: T
authors.lastname: Phenrat
authors.forename: Stella
authors.initials: S
authors.lastname: Marinakos
authors.forename: Yao
authors.initials: Y
authors.lastname: Xiao
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wiesner
authors.forename: Robert D
authors.initials: RD
authors.lastname: Tilton
authors.forename: Gregory V
authors.initials: GV
authors.lastname: Lowry
mesh_terms: D024202:Electrophoretic Mobility Shift Assay; D004785:Environmental Pollutants / Q000737:chemistry*; D006170:Gum Arabic / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D053768:Metal Nanoparticles / Q000737:chemistry*; D008956:Models, Chemical; D011205:Povidone / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013818:Thermogravimetry
chemical_list: D004785:Environmental Pollutants; D012834:Silver; D006170:Gum Arabic; D011205:Povidone