EXAFS study of adsorbed Cu(II) on fly ashes with different residual carbon contents.

This work studied the speciation of copper species adsorbed onto the surface of fly ash using X-ray absorption spectroscopy (XAS). Experimental results verified that the chemical bond between Cu(II) and the surface of the fly ash was Cu-O. The data set was optimally fitted into the two atomic shells: the first shell containing O atoms and the second shell containing Cu atoms. The extended X-ray absorption fine structure (EXAFS) data also show that, in the first shell, about 2.03-2.41 nearest oxygen atoms surround the center Cu atom with a Cu-O bond distance of 1.96-1.99 A. The results further demonstrated that the bond distance slightly increased with an increasing carbon content of the fly ash.