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Exchange of Surfactant by Natural Organic Matter on the Surfaces of Multi-Walled Carbon Nanotubes
Chang, X. AND D. Bouchard. Exchange of Surfactant by Natural Organic Matter on the Surfaces of Multi-Walled Carbon Nanotubes. 250th American Chemical Society National Meeting & Exposition, Boston, MA, August 15 - 21, 2015.
Presentation given at 2015 ACS Fall Meeting.
The increasing production and applications of multi-walled carbon nanotubes (MWCNTs) have elicited concerns regarding their release and potential adverse effects in the environment. To form stable aqueous MWCNTs suspensions, surfactants are often employed to facilitate dispersion of the inherently hydrophobic MWCNTs in water. It has been reported that natural organic matter (NOM) is also efficient at dispersing and stabilizing MWCNTs. Upon the release of surfactant-wrapped MWCNTs to the environment, there is a possibility that the exchange of surfactant by NOM could occur on MWCNTs surfaces. Unfortunately, this process has not been studied and is incompletely understood. The present study investigates the stability of association between surfactant and MWCNTs in the presence of NOM. 14C-labelled sodium dodecyl sulfate (14C-SDS) is employed to disperse MWCNTs to form stable aqueous MWCNTs suspensions (14C-SDS-MWCNTs). The free 14C-SDS and 14C-SDS-MWCNTs are separated by filtration and SDS quantitation is performed using liquid scintillation counting. The release of MWCNTs associated 14C-SDS as a function of ionic strength and NOM concentration are investigated. The effects of surfactant/NOM exchange on MWCNTs properties (e.g., surface charge, aggregation, and deposition) are tested using phase analysis light scattering, dynamic lighter scattering, and quartz crystal microbalance with dissipation monitoring. The results of this work will advance our understanding of the nature of MWCNT surface decoration after release into the environment.
Record Details:Record Type: DOCUMENT (PRESENTATION/SLIDE)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LABORATORY
ECOSYSTEMS RESEARCH DIVISION
REGULATORY SUPPORT BRANCH