title: Mobility of functionalized quantum dots and a model polystyrene nanoparticle in saturated quartz sand and loamy sand.
abstract: Quantum dots (QDs) are one example of engineered nanoparticles (ENPs) with demonstrated toxic effects. Yet, little is known about the behavior of QDs in the natural environment. This study assessed the transport of two commercial carboxylated QDs (CdTe and CdSe) and carboxylated polystyrene latex (nPL) as a model nanoparticle using saturated laboratory-scale columns. The influence of solution ionic strength (IS) and cation type (K(+) or Ca(2+)) on the transport potential of these ENPs was examined in two granular matrices - quartz sand and loamy sand. The retention of all three particles was generally low in the quartz sand columns within the range of studied IS (0.1-100 mM) for the monovalent salt (KCl). In contrast, the retention of the three ENPs in the quartz sand was significant in the presence of 10 mM Ca(2+). Moreover, ENP attachment efficiencies (α) were enhanced by at least 1 order of magnitude in columns packed with loamy sand (for IS between 0.1-10 mM KCl). Although all three ENPs used here are carboxylated, they differ in the type of surface coating (e.g., choice of polymers or polyelectrolytes). Regardless of the surface coatings, the three ENPs exhibit comparable mobility in the quartz sand. However, the ENPs demonstrate variable transport potential in loamy sand suggesting that differences in the binding affinities of surface-modified ENPs for specific soil constituents can play a key role in the fate of ENPs in soils.
authors.affiliation: Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 2B2, Canada.
authors.forename: Ivan R
authors.initials: IR
authors.lastname: Quevedo
authors.forename: Nathalie
authors.initials: N
authors.lastname: Tufenkji
mesh_terms: D002122:Calcium Chloride / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry*; D011189:Potassium Chloride / Q000737:chemistry; D045663:Quantum Dots; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D011137:Polystyrenes; D011189:Potassium Chloride; D012822:Silicon Dioxide; D002122:Calcium Chloride