Affiliations: State Key Laboratory of Soil and Sustainable
Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing
210008, China | Department of Civil and Environmental Engineering,
Northeastern University, Boston, Massachusetts, USA
Abstract: The electrokinetic removal of chromium and copper from
contaminated soils by adding lactic acid in cathode chamber as an enhancing
reagent was evaluated. Two sets of duplicate experiments with chromium
contaminated kaolinite and with a silty soil sampled from a superfund site in
California of USA and polluted by Cr and Cu, were carried out in a constant
current mode. Changes of soil water content and soil pH before and after the
electrokinetic experiments, and variations of voltage drop and electroosmosis
flow during the treatments were examined. The results indicated that Cr, spiked
as Cr (VI) in the kaolinite, was accumulated mainly in the anode
chamber, and some of Cr and metal hydroxides precipitated in the soil sections
in contact with the cathode, which significantly increased electrical energy
consumption. Treatment of the soil collected from the site showed accumulation
of large amounts of Cr and Cu in the anode chamber while none was detected in
the cathode one. The results suggested that the two metals either complexed
with the injected lactic acid at the cathode or existed as negatively charged
complex, and electromigrated toward the anode under a voltage gradient.
