Association of the sites of heavy metals with nanoscale carbon in a Kentucky electrostatic precipitator fly ash

James C. Hower, Uschi M. Graham, Alan Dozier, Michael T. Tseng, Rajesh A. Khatri

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

Abstract

A combination of high-resolution transmission electron microscopy, scanning transmission electron microscopy, and electron energy-loss spectroscopy (HRTEM-STEM-EELS) was used to study fly ashes produced from the combustion of an eastern Kentucky coal at a southeastern-Kentucky wall-fired pulverized coal utility boiler. Fly ash was collected from individual hoppers in each row of the electrostatic precipitators (ESP) pollution-control system, with multiple hoppers sampled within each of the three rows. Temperatures within the ESP array range from about 200°C at the entry to the first row to <150°C at the exit of the third row. HRTEM-STEM-EELS study demonstrated the presence of nanoscale (10 s nm) C agglomerates with typical soot-like appearance and others with graphitic fullerene-like nanocarbon structures. The minute carbon agglomerates are typically juxtaposed and intergrown with slightly larger aluminosilicate spheres and often form an ultrathin halo or deposit on the fly ash particles. The STEM-EELS analyses revealed that the nanocarbon agglomerates host even finer (<3 nm) metal and metal oxide particles. Elemental analysis indicated an association of Hg with the nanocarbon. Arsenic, Se, Pb, Co, and traces of Ti and Ba are often associated with Fe-rich particles within the nanocarbon deposits.

Original languageEnglish
Pages (from-to)8471-8477
Number of pages7
JournalEnvironmental Science and Technology
Volume42
Issue number22
DOIs
StatePublished - Nov 15 2008

ASJC Scopus subject areas

  • Chemistry (all)
  • Environmental Chemistry

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