Reductive dechlorination of carbon tetrachloride by zero-valent iron and related iron corrosion

Electrochemical corrosion behavior of iron in aqueous solutions with and without carbon tetrachloride (CT) was investigated in a wide pH range from 0.4 to 14 using steady-state polarization curves and electrochemical impedance spectroscopy (EIS). It was found that the presence of CT significantly accelerated the hydrogen evolution reaction (HER) on the iron surface in strong acidic solutions, causing severe corrosion of iron; in return, the iron corrosion was helpful for the reductive dechlorination of CT. The inherent relationship between the dechlorination of CT and the corrosion of iron is attributed to the fact that the adsorbed hydrogen atoms produced during the iron corrosion process are necessary for the dechlorination process of CT. As a result, the removal efficiency of CT is strongly dependent on the extent of iron corrosion in aqueous solutions at different pH values.