Drinking water disinfection by hemin-modified graphite felt and electrogenerated reactive oxygen species

The electrochemical inactivation of microorganisms by a hemin/graphite felt (GF) composite electrode was investigated, and Escherichia coli was treated as the testing species. The composite electrode was constructed by chemically bonding hemin molecules onto an amino-mineralized GF (AGF) surface. Then, the electrode was characterized systematically by electrochemical methods, and the kinetic parameters of the modified electrode were investigated. The hemin molecules on the surface of the composite electrode have high activity for the reduction of O2. When the composite electrode was applied with negative potentials, the dissolved oxygen was electrochemically reduced to reactive oxygen species (ROS, such as H2O2 and OH) at the cathode surface. The ROS can cause biological damage and can eventually result in the death of bacteria. A sterilizing rate up to 99.9% could be obtained after 60 min of inactivation. Thus, this composite electrode could be applied to disinfect drinking water efficiently at a low potential (−0.6 V vs. SCE) without any addition of chloride.

► A hemin/graphite felt composite electrode, bonding hemin molecules on to the amino mineralized graphite felt surface, was successfully used as working electrode for the electrochemical inactivation of E. coli.
► The main contribution to the bacteria inactivation process is the oxidation in the liquid bulk by in situ electrogenerated reactive oxygen species (ROS).
► The ROS demonstrated to be sufficient to perform an effective disinfection, without the mediation of active chlorine substance.