In-situ EXAFS study of copper in the electrokinetic remediation process

The speciation of copper in the early stage of the electrokinetic remediati on (EKR) process has been studied by extended X-ray absorption fine structu re (EXAFS) spectroscopy in the present work. By in-situ EXAFS, we found tha t copper in a contaminated soil possessed a Cu-O bond distance of 1.98 Angs trom with a coordination number (CN) of 5.8. In the second shell, the bond distance of Cu(O)-Cu was 2.87 Angstrom with a CN of 6.4. However, possibly due to the fact that incompact copper atoms in the outer shells were distor ted by EKR, the Cu-(O)-Cu (2nd shell) bond distance and the CN of copper in the contaminated soil decreased by 0.08 Angstrom and 5.4, respectively in the early stage of the EKR process. Interestingly, after prolonging the con tact time to about 80 minutes, the 1st-shell copper atoms were also perturb ed by EKR. This work is an example of usefulness of the in-situ EXAFS spect roscopy for detailed studies of the speciation of copper in the contaminate d soil during EKR process.