D. Hesterberg et al., XAFS CHARACTERIZATION OF COPPER IN MODEL AQUEOUS SYSTEMS OF HUMIC-ACID AND ILLITE, Journal de physique. IV, 7(C2), 1997, pp. 833-834
Adsorption of heavy metals at mineral surfaces and complexation with r
eactive organic-matter functional groups are important processes regul
ating the solubility and fate of soil contaminants. To determine the n
ature of Cu(II) bonding in complex clay-organic systems, XAFS analyses
were conducted on aqueous suspensions containing Cu(II) in various fo
rms: (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. Sp
ectral features for Cu bound to HA did not depend significantly on the
HA:Cu ratio, and average first-shell Cu-O bond lengths were consisten
tly shorter than for the Cu-illite systems. In the mixed clay-organic
suspension, Cu bonding was more characteristic to that of Cu bound wit
h HA.