ENVR 92 |
| Buckminsterfullerene, C60, has attracted widespread attention due to its potential applications in diverse fields. With consumer products containing fullerene already available in the market, fullerene contamination of natural aquatic systems may become a major concern. In aqueous solutions, hydrophobic fullerene molecules bind strongly together to form negatively charged fullerene nanoparticles. To better understand the fate, transport and reactivity of these nanoparticles in natural aquatic systems, we investigate their aggregation kinetics in Suwannee River humic acid solutions in the presence of common monovalent and divalent electrolytes by employing time-resolved dynamic light scattering. In the absence of humic acid, the aggregation behavior of the fullerene nanoparticles in the presence of sodium, magnesium and calcium ions was consistent with the classic DLVO theory. In the presence of humic acid and sodium or magnesium ions, humic acid adsorbed onto the fullerene nanoparticles, causing steric stabilization. This increase in the nanoparticle stability was also observed in the presence of humic acid at low calcium ion concentrations; however, enhanced aggregation occurred at higher calcium concentrations. Light scattering measurements and TEM imaging of the fullerene aggregate structures indicated that humic acid aggregated to bridge the fullerene nanoparticles together, leading to the observed enhanced aggregation. |
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The C. Ellen Gonter Environmental Chemistry Awards
1:30 PM-4:35 PM, Tuesday, August 21, 2007 Boston Park Plaza -- Beacon Hill Rm, Oral
Division of Environmental Chemistry |