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 Å. The results further demonstrated that the bond distance slightly increased with an increasing carbon content of the fly ash.