Formation of disinfection byproducts (DBPs) such as trihalomethanes (THMs), haloacetic acids (HAAs) and others is recognized as the major drawback of drinking water disinfection based on chlorination.
In this project, we are investigating electrochemical disinfection of drinking water using graphene sponge electrodes. As graphene coating has very low electrocatalytic activity towards chloride, the formation of toxic and persistent chlorate and perchlorate, typical of all commercial anode materials including boron-doped diamond (BDD) anodes, is completely avoided. At the same time, current efficiency of chlorine formation at graphene sponge anode is less than 0.1% for brackish solutions (i.e., 20-30 mM chloride), whereas for chloride concentrations typical of drinking water, no chlorine formation is observed. This effectively eliminates the possibility of forming DBPs (THMs, HAAS and other halogenated byproducts) during electrochemical treatment of tap water.
The nanostructured surface of graphene-based sponge electrodes enables the killing of the bacteria and viruses via multiple mechanisms, such as electroporation, disinfection via the in situ formed reactive oxygen species (e.g., O3), and electrosorption and direct electron transfer at the anode surface. Furthermore, the capacitance of graphene opens up the possibility of operating the reactor with intermittent current supply instead of continuous, which can reduce drastically the energy consumption of the system.