Speciation of copper in a contaminated soil during H3PO4-assisted EKR

Speciation of copper in a contaminated soil during electrokinetic remediation (EKR) assisted by H3PO4 was studied by in situ X-ray absorption near edge structural (XANES) spectroscopy. The least-square fit of the XANES spectrum showed that CuCO3 (68%) and CuCl2 (32%) were the major copper species in the contaminated soil. In the presence of H3PO4 (40%), most of CuCl2 and about 24% of CuCO3 were dissolved into the aqueous phase. After 90 min of EKR, at least 30% of Cu(II) ions were transported towards the cathode by electric field. A similar dissolution behavior of copper from the soil with 40% H3PO4 and 2% H2O2 was also observed. Nevertheless, migration of Cu(II) ions to the cathode was highly enhanced in the presence of H3PO4 and H2O2 by EKR for the first 90 min.