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Multiwalled Carbon Nanotube Dispersion Methods Affect Their Aggregation, Deposition, and Biomarker Response
Citation:
Chang, X., Matt Henderson, AND D. Bouchard. Multiwalled Carbon Nanotube Dispersion Methods Affect Their Aggregation, Deposition, and Biomarker Response. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 49(11):6645-6653, (2015).
Impact/Purpose:
The purpose of this study is to systematically evaluate effects of the two dispersion methods (ultrasonication and long-term stirring) and various dispersants [natural water, small molecular weight organic acids, surfactants, and natural organic matter (NOM)] on MWNTs’ environmental behavior. MWNTs’ suspension properties including mass concentration, surface charge, morphology, size, and size distribution were characterized with a range of instruments. Dispersion methods effects on MWNT homo-aggregation and hetero-aggregation (deposition), and on exposure biomarkers (fathead minnow cell cultures), were also evaluated.
Description:
To systematically evaluate how dispersion methods affect the environmental behaviors of multiwalled carbon nanotubes (MWNTs), MWNTs were dispersed in various solutions (e.g., surfactants, natural organic matter (NOM), and etc.) via ultrasonication (SON) and long-term stirring (LT). The two tested surfactants [anionic sodium dodecyl sulfate (SDS) and nonionic poly(ethylene glycol)–poly(propylene glycol)–poly(ethylene glycol) (PEO–PPO–PEO) triblock copolymers (Pluronic)] could only disperse MWNTs via ultrasonication; while stable aqueous SON/MWNT and LT/MWNT suspensions were formed in the presence of the two model NOMs (Suwannee river humic acid and fulvic acid). Due to the inherent stochastic nature for both methods, the formed MWNT suspensions were highly heterogeneous. Their physicochemical properties, including surface charge, size, and morphology, greatly depended upon the dispersant type and concentration but were not very sensitive to the preparation methods. Aggregation and deposition behaviors of the dispersed MWNTs were controlled by van der Waal and electrostatic forces, as well as other non-DLVO forces (e.g., steric, hydrophobic forces, etc.). Unlike the preparation method-independent physicochemical properties, LT/NOM-MWNTs and SON/NOM-MWNTs differed in their fathead minnow epithelial cell metabolomics profiles.
