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Characterization of Carbon Onion Nanomaterials for Environmental Remediation
Li, Y., C. SU, A. Bailes, AND Y. Lu. Characterization of Carbon Onion Nanomaterials for Environmental Remediation. Presented at The American Geophysical Union 2009 Fall Meeting, San Francisco, CA, December 14 - 18, 2009.
To introduce a relatively new carbonaceous nanomaterial, i.e. carbon onion nanomaterials, which were produced in a cost-effective way of about $1/g, by oxygen-depleted combustion of hydrocarbon gases.
The unique properties of carbonaceous nanomaterials, including small particle size, high surface area, and manipulatable surface chemistry, provide high potential for their application to environmental remediation. While research has devoted to develop nanotechnology for environmental application using carbonaceous nanomaterials, e.g. carbon nanotube and C60 fullerene, the practical application is limited due to their high cost of production of about $50-100/g. We introduce a relatively new carbonaceous nanomaterial, i.e. carbon onion nanomaterials, which were produced in a cost-effective way of about $1/g, by oxygen-depleted combustion of hydrocarbon gases. Carbon onion nanomaterials consist of spherical fullerene cores surrounded by onion-like nested spherical graphite layers, with diameters of around 20 nm. In this work we characterized the properties of carbon onion nanomaterials to investigate their potential application for environmental remediation. The dry carbon onion powders were first characterized using transmission electron microcopy (TEM), X-ray diffraction (XRD), and gas sorption Surface Area Analyzer. Sorption capacity of carbon onion nanomaterials for heavy metals, including Zn(II), Ni(II), Pb(II), Cd(II), and Cu(II), was explored using different pH conditions and surface modification approaches. We found that carbon onion nanomaterials can effectively adsorb heavy metal contaminants at high pH or when surface functionalized with carboxylate groups. Stable aqueous suspension of carbon onion aggregates was produced by exchange of toluene organic solvent. The properties of carbon onion aggregates in aqueous suspension, including particle size, zeta potential, and concentration, were determined using a Zetasizer Nano ZS analyzer, Scanning Electron Microscope (SEM) / Energy-Dispersive X-Ray (EDX), and UV-VIS Scanning Spectrophotometer. Carbon onion nanomaterials were found to be very well dispersed in aqueous phase, forming stable aggregates with a hydrodynamic diameter of about 180 nm. Column experiments were conducted to evaluate the transport of carbon onion aggregates in Ottawa sand. The mobility of carbon onion aggregates was found to be influenced by the electrolyte types with higher mobility in NaCl than in CaCl2.