FULLERENES AND METALLOFULLERENES IN COAL-FIRED STOKER FLY ASH: EXAMPLES FROM A KENTUCKY POWER PLANT

A suite of high-As, high-C fly ashes from a university-based stoker-fired coal boiler were analyzed by a number of techniques, including polarized-light, oil-immersion optical microscopy; high-resolution transmission electron microscopy (HR-TEM); time-of-flight secondary ion mass spectrometry (TOF-SIMS); X-ray photoelectron spectroscopy (XPS); and field-emission scanning electron microscopy (FE-SEM). A sooty carbon phase is in the form of nanometer-scale balls with the major fullerenes at C₆₀⁺, C₇₀⁺, and C₈₀⁺, with species at C₂ increments from C₅₆⁺ to C₇₈⁺. Arsenic and Hg, among other metals, are found in association with the fullerenes, but, with our techniques, it is not possible to determine if the metals are encapsulated by the fullerenes or attached to the side of the structure. TOF-SIMS studies suggest an association of As with the Al-Si glass; an association of Pb with oxides, sulfates, and carbon; Hg with carbon; Se in elemental form with carbon; and Cr in a variety of forms, including nano carbons, Fe sulfates and oxides, glass, and Cr-oxyhydroxides.