Geochemistry of carbon nanotube assemblages in coal fire soot, Ruth Mullins fire, Perry County, Kentucky

Coal fires typically generate a variety of mineral and organic deposits associated with the venting emission gases. In addition to the tars typically found at the Ruth Mullins coal fire, Perry County, Kentucky, a sooty carbon, superficially similar to a carbon from a university-based stoker-fired power plant, was sampled in an August 2010 visit. Carbons in the soot include complex carbon particles, nanotubes encapsulating Hg, onion-like structures with polyhedral and quasi-spherical morphology with hollow centers, and metal-bearing multiwalled nanotubes. Mineral and amorphous inorganic phases included glassy Al-Si spheres with associated Pb and Se; nanopyrite grains with trace As and Se; nanohematite with V ³⁺; salammoniac; quartz; Cr- and Pb-bearing jarosite; fibrous pickeringite with surficial natrojarosite; and Cd-, Co-, Mo-, Ni, V-, W-, and Zr-bearing nanospheres. The enrichment of ¹⁵N in the soot is associated with the fractionation of NH ₃ to NH ₄ in the formation of salammoniac. Selenium, Pb, and Zn are found in relatively high concentrations in the soot and Hg, with 5.68ppm, has a higher concentration than any Kentucky fly ash.