title: Hydrophobicity of biofilm coatings influences the transport dynamics of polystyrene nanoparticles in biofilm-coated sand.
abstract: Engineered nanoparticles (ENPs) are used in the manufacture of over 2000 industrial and consumer products to enhance their material properties and functions or to enable new nanoparticle-dependent functions. The widespread use of ENPs will result in their release to the subsurface and aquatic environments, where they will interact with indigenous biota. Laboratory column experiments were designed to understand the influence of two different Pseudomonas aeruginosa biofilms on the mobility of polystyrene latex nanoparticles in granular porous media representative of groundwater aquifers or riverbank filtration settings. The transport behavior of 20 nm carboxylate-modified (CLPs) and sulfate (SLPs) polystyrene latex ENPs suspended in NaCl or CaCl2 (1 and 10 mM ionic strength, pH 7) was studied in columns packed with quartz sand coated with biofilms formed by two P. aeruginosa strains that differed in cell surface hydrophobicity (P. aeruginosa 9027™, relatively hydrophilic and P. aeruginosa PAO1, relatively hydrophobic). Biofilm-coated quartz sand retained more of the electrostatically-stabilized latex ENPs than clean, uncoated sand, regardless of the serotype. As IS increased, clear differences in the shape of the ENP breakthrough curves were observed for each type of biofilm coating. ENP breakthrough in the P. aeruginosa PAO1 biofilm-coated sand was generally constant with time whereby breakthrough in the P. aeruginosa 9027 biofilm-coated sand showed dynamic behavior. This indicates a fundamental difference in the mechanisms of ENP deposition onto hydrophilic or hydrophobic biofilm coatings due to the hydration properties of these biofilms. The results of this study demonstrate the importance of considering the surface properties of aquifer grain coatings when evaluating ENP fate in natural subsurface environments.
authors: Department of Chemical Engineering, McGill University, Montreal, Quebec, H3A 0C5, Canada; Department of Natural Resource Sciences, McGill University, Montreal, Quebec, H3A 0C5, Canada.
authors: Michael R
authors: MR
authors: Mitzel
authors: Department of Chemical Engineering, McGill University, Montreal, Quebec, H3A 0C5, Canada; Department of Water Science, Universität Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany.
authors: Stefanie
authors: S
authors: Sand
authors: Department of Natural Resource Sciences, McGill University, Montreal, Quebec, H3A 0C5, Canada.
authors: Joann K
authors: JK
authors: Whalen
authors: Department of Chemical Engineering, McGill University, Montreal, Quebec, H3A 0C5, Canada. Electronic address: nathalie.tufenkji@mcgill.ca.
authors: Nathalie
authors: N
authors: Tufenkji
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D002264:Carboxylic Acids / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008863:Microspheres; D053758:Nanoparticles / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D012822:Silicon Dioxide / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry
chemical_list: D002264:Carboxylic Acids; D011137:Polystyrenes; D013431:Sulfates; D012822:Silicon Dioxide
keywords: Biofilm; Fate; Filtration; Hydrophobicity; Nanoparticle; Transport