J. Phys. IV France 7 (1997) C2-833-C2-834
XAFS Characterization of Copper in Model Aqueous Systems of Humic Acid and IlliteD. Hesterberg1, D.E. Sayers2, W. Zhou2, W.P. Robarge1 and G.M. Plummer2
1 Department of Soil Science, Box 7619, North Carolina State University, Raleigh NC 27695, U.S.A.
2 Department of Physics, Box 7518, North Carolina State University, Raleigh NC 27695, U.S.A.
Adsorption of heavy metals at mineral surfaces and complexation with reactive organic-matter functional groups are important processes regulating the solubility and fate of soil contaminants. To determine the nature of Cu(II) bonding in complex clay-organic systems, XAFS analyses were conducted on aqueous suspensions containing Cu(II) in various forms : (i) complexed with soil humic acid (HA) at various HA : Cu ratios, (ii) bound to illite, or (iii) bound in a mixture of illite and HA. Spectral features for Cu bound to HA did not depend significantly on the HA : Cu ratio, and average first-shell Cu-O bond lengths were consistently shorter than for the Cu-illite systems. In the mixed clay-organic suspension, Cu bonding was more characteristic to that of Cu bound with HA.
© EDP Sciences 1997