AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Oxidation of Aerosolized C60 by Ozone
Andrea Tiwari, LINSEY MARR, Virginia Tech
Abstract Number: 152 Working Group: Engineered Nanoparticles: Emissions, Transformation and Exposure
Abstract Manufactured carbonaceous nanoparticles, such as C$_(60) fullerenes, will enter the atmosphere during production, use, and disposal. There, they will be subject to chemical and physical transformations that could modify their properties and ultimately their fate, transport, and toxicity within the environment. The objective of this research is to determine the products and possible environmental impacts of the reaction of C$_(60) aerosols with atmospherically relevant concentrations of O$_3. C$_(60) was aerosolized into a 6 m$^3 Teflon chamber through dispersion of the powdered nanomaterial, producing a size distribution that peaked around 100 nm. The aerosols were then exposed to O$_3 concentrations of 45-120 ppb at relative humidities of ~15% and ~65%. Following exposure to ozone, aerosols were collected onto filters, copper tape, and copper grids for chemical and physical analysis by high performance liquid chromatography (HPLC), x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Results indicated that the reaction proceeded within minutes and appeared to be complete in less than 1 h. Reaction products included C$_(60)O, C$_(60)O$_2, and C$_(60)O$_3. Continued O$_3 uptake and the appearance of a brownish, toluene-insoluble residue suggested the formation of a C$_(60) polymer on the aerosol surface. The presence of water vapor enhanced ozone loss, oxygen uptake, the oxygen content of the aerosol surface, and the initial rate of formation for oxide reaction products. Results of assays for reactive oxygen species and mutagenicity indicated that exposure to ozone may affect the toxicity of C$_(60) aerosols. At atmospherically relevant O$_3 levels, C$_(60) may be rapidly oxidized, and this process may affect its fate, transport, and toxicity in the environment.