title: Extensive FE-SEM/EDS, HR-TEM/EDS and ToF-SIMS studies of micron- to nano-particles in anthracite fly ash.
abstract: The generation of anthropogenic carbonaceous matter and mixed crystalline/amorphous mineral ultrafine/nano-particles in the 1 to 100 nm size range by worldwide coal power plants represents serious environmental problems due to their potential hazards. Coal fly ash (CFA) that resulted from anthracite combustion in a Portuguese thermal power plant was studied in this work. The physico-chemical characterization of ultrafine/nano-particles present in the CFA samples and their interaction with environment are the aim of this study. The methodologies applied for this work were field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy (HR-TEM/EDS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Some hazardous volatile elements, C, N, S and Hg contents were also determined in the studied samples. Generally, the CFA samples comprise carbonaceous, glassy and metallic solid spheres with some containing mixed amorphous/crystalline phases. The EDS analysis coupled with the FE-SEM and HR-TEM observations of the fly ash particles with 100 to 0.1 nm demonstrates that these materials contain a small but significant proportion of encapsulated HVEs. In addition, the presence of abundant multi-walled carbon nanotubes (MWCNTs) and amorphous carbon particles, both containing hazardous volatile elements (HVEs), was also evidenced by the FE-SEM/EDS and HR-TEM/EDS analysis. A wide range of organic and inorganic compounds was determined by chemical maps obtained in ToF-SIMS analysis.
authors.affiliation: Centro de Geologia, Universidade do Porto, Porto, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Ribeiro
authors.forename: Kátia
authors.initials: K
authors.lastname: DaBoit
authors.forename: Deolinda
authors.initials: D
authors.lastname: Flores
authors.forename: Marcio A
authors.initials: MA
authors.lastname: Kronbauer
authors.forename: Luis F O
authors.initials: LF
authors.lastname: Silva
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D003031:Coal / Q000032:analysis; D060729:Coal Ash / Q000032:analysis* / Q000737:chemistry; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D053758:Nanoparticles / Q000032:analysis*; D037742:Nanotubes, Carbon / Q000032:analysis; D011174:Portugal; D011210:Power Plants; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods*; D013052:Spectrometry, X-Ray Emission / Q000379:methods*
chemical_list: D000393:Air Pollutants; D003031:Coal; D060729:Coal Ash; D037742:Nanotubes, Carbon