Enhanced chlorine dioxide decay in the presence of metal oxides in drinking water distribution systems

Abstract

The present study focused on enhanced chlorine dioxide (ClO2) decay in the presence of metal oxides formed in drinking water distribution systems due to metal pipe corrosion phenomena. Chlorine dioxide decays via three pathways: 1) catalytic disproportionation which produces equal molar amounts of chlorite and chlorate, 2) the decay to chlorite and oxygen and 3) oxidation of metals to a higher oxidation state. Cupric oxide (CuO) and nickel oxide (NiO) showed significantly stronger ability to catalyze the ClO2 disproportionation than goethite (a-FeOOH). CuO and NiO also enhanced ClO2 decay to produce chlorite and oxygen. Chlorine dioxide can oxidize cuprous oxide (Cu2O) to CuO, with the release of chlorite. The interaction between metal oxides and chlorine dioxide will raise an issue on how to maintain oxidant residual in drinking water distribution systems.