Aggregation and Fate of Fullerene Nanoparticles in Aquatic Environments
K.L. Chen and M. Elimelech
Yale University, US
aggregation, fullerene, dynamic light scattering, nanoparticles
Fullerene has unique chemical properties and physical structure, and is emerging in a wide range of electronics and biomedical applications. However, toxicity studies have raised concern that fullerene may have adverse human health effects. With the fast growth in the use of fullerene products, fullerenes may end up in natural and engineered aquatic systems. Due to the hydrophobic nature of fullerene, fullerene molecules bind strongly together forming stable nanoparticles in aqueous solution. To predict the fate and transport of these nanoparticles, it is crucial to understand the influence of solution chemistry on their aggregation behavior. In this study, fullerene nanoparticles synthesized through two techniques are aggregated over different ionic strengths (NaCl). Aggregation kinetics are followed through dynamic light scattering. As salt concentration increases, aggregation occurs faster until the aggregation kinetics reach a maximum controlled by diffusion. Both nanoparticles undergo fast diffusive aggregation at NaCl concentrations consistent with aquatic systems of high salinity. This implies that fullerene nanoparticles are likely to aggregate forming bigger aggregate structures under high salt conditions, eventually settling out from the bulk phase of aquatic systems. The influence of divalent salt (calcium chloride) and natural organic matter on the aggregation kinetics and mechanisms involved will be discussed.
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Nanotech 2006 Conference Program Abstract