C60 fullerenes from combustion of common fuels

Releases of C-60 fullerenes to the environment will increase with the growth of nanotechnology. Assessing the potential risks of manufactured C-60 requires an understanding of how its prevalence in the environment compares to that of natural and incidental C-60. This work describes the characterization of incidental C-60 present in aerosols generated by combustion of five common fuels: coal, firewood, diesel, gasoline, and propane. C-60 was found in exhaust generated by all five fuels; the highest concentrations in terms of mass of C-60 permass of particulate matter were associated with diesel and coal. Individual aerosols from these combustion processes were examined by transmission electron microscopy. No relationship was found between C-60 content and either the separation of graphitic layers (lamellae) within the particles, nor the curvature of those lamellae. Estimated global emissions of incidental C-60 to the atmosphere from coal and diesel combustion range from 1.6 to 6.3 t yr(-1), depending upon combustion conditions. These emissions may be similar in magnitude to the total amount of manufactured C-60 produced on an annual basis. Consequent loading of incidental C-60 to the environment may be several orders of magnitude higher than has previously been modeled for manufactured C-60. (C) 2015 Elsevier B.V. All rights reserved.