High Resolution TEM Investigation of Ultrafine PM Derived from Coal Combustion: Are we regulating the right thing?

摘要

Ultrafine particles (<100nm) derived from coal fly ashes (CFA) produced by the combustion of three U.S. coals have been examined by high resolution transmission electron microscopy (HRTEM), using HR imaging, electron diffraction, electron energy-loss spectroscopy (EELS), energy-filtered transmission electron microscopy (EFTEM), and energy dispersive x-ray (EDX) spectroscopy. EFTEM C and O K-edge maps combined with Si, Al, Ti and Fe L-edge maps revealed abundant UFP crystalline particles rich in Fe, Ti and Al in bituminous CFA with sizes from a few nanometers to several hundred nanometers. Electron diffraction established that these UFP were predominantly rutile, iron-rich spinels, Fe-, Ti-, and Fe-Ti-aluminates and Fe-Ti-aluminosilicates. The UFP fraction of western low-rank CFA contained considerable amounts of Ca-sulfates and Ca-phosphates, as well as mixed species.