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Electrokinetic Properties of Fullerene nC60 Nanoparticles: Role of Co-ions and pH
Citation:
Mukherjee, B. AND J. W. WEAVER. Electrokinetic Properties of Fullerene nC60 Nanoparticles: Role of Co-ions and pH. Presented at Nano 2010: Environmental Effects of Nanoparticles and Nanomaterials, Clemson, SC, August 22 - 26, 2010.
Impact/Purpose:
Presentation of research at a scientific meeting.
Description:
Environmental exposure, bioavailability, and mobility of nanoparticles (NPs) in part depend on their aggregated state and their surface charge. These fundamental characteristics are functions of the aqueous media in which the particles are suspended. For example, inorganic ions play a significant role in determining the aggregation and electrokinetic properties of NPs. Although the role of counter-ions (ions charged oppositely to the surface charge of NPs) has been addressed by several previous studies, the literature on the role of co-ions (ions charged similarly to the surface charge of NPs) is relatively sparse. Co-ions can impact particle surface charges by preferential adsorption. This phenomenon has been debated as one possible explanation for the acquisition of negative surface charge by fullerene nC60 nanoparticles (NPs) in aqueous media. In this research, a comparative study of the effects of two co-ions (SO42- and Cl-) on the electrokinetic and initial aggregation behaviors of suspended nC60 NPs was made under acidic (~3.0), near neutral (~6.0), and alkaline (~10.0) pH conditions. In the presence of a monovalent counter-ion (Na+, 10 mM), both the co-ions similarly affected the change in the average aggregate size (DH,) and the electrophoretic mobility (UE,) of nC60 NPs. All these findings indicate fundamental differences in the interfacial interaction characteristics of nC60 NPs with co-ions and the pivotal role played by pH (i.e., OH-), which may allow us to better assess the behavior of nC60 in aquatic environments.