Electrokinetic movement of multiple chlorobenzenes in contaminated soils in the presence of beta-cyclodextrin.

This study investigated the electrokinetic (EK) behavior of multiple chlorobenzenes, including 1,2,3,4-tetrachlorobenzene (TeCB), 1,2,4,5-tetrachlorobenzene (i-TeCB), and 1,2,3-trichlorobenzene (TCB) in contaminated clayed soils. The effect of beta-cyclodextrin (beta-CD) on the EK removal of the chlorobenzenes was studied. The largest removal was obtained when Na2CO3/NaHCO3 buffer was used as anodic purging solution without beta-CD. The removal efficiencies were related to the aqueous solubilities of chlorobenzenes. With the same cumulative electroosmotic flow, greater solubility led to higher removal efficiency. The addition of beta-CD inhibited the EK removal efficiency of all chlorobenzenes. The inhibition increased with the increase of beta-CD concentration. With the same beta-CD concentration, the inhibition increased with the rise of electric potential. It was found that the inclusion compounds between beta-CD and chlorobenzenzes were less soluble than chlorobenzenes. The formation of the less soluble inclusion compounds reduced the aqueous solubility of chlorobenzenes and led to the partial immobilization of the chlorobenzenes that desorbed from soil. It was feasible to use the EK technology to remove chlorobenzenes in contaminated soils using water as the anodic flushing solution. The addition of beta-CD was not recommended for the EK removal of chlorobenzenes.