Abstract:
The effect of Cu(II) ion on the dechlorination of carbon tetrachloride (CT) by Fe(II) associated with
various iron oxides was investigated. Iron oxides including goethite, hematite, ferrihydrite and magnetite
were selected as the model compounds. CT was dechlorinated to chloroform (CF) by 3 mM Fe(II) in iron
oxide suspensions at pH 7.2. The dechlorination followed pseudo first-order kinetics and the pseudo first order rate constants (kobs) were 0.048 h–1, 0.0836 h–1, 0.0609 h–1 and 0.0144 h–1 in goethite-, hematite-,
ferrihydrite- and magnetite-amended systems, respectively. Addition of Cu(II) into systems increased the
kobs for CT dechlorination significantly. A 3- to 120-fold increase in kobs relative to the systems without Cu(II)
was observed when 0.5 mM Cu(II) was added to the Fe(II)-Fe(III) suspensions. The pH of the system is an
important factor controlling the dechlorination rate of CT. The increase in concentrations of Fe(II) and iron
oxides also enhanced the dechlorination efficiency and rate of CT. Moreover, a linear relationship between
the kobs and Cu(II) concentration ranging between 0 and 0.4 mM was observed. Results obtained
demonstrate the feasibility of using surface-bound iron species with Cu(II) for the detoxification of
chlorinated solvents in the contaminated aquifers.
