The effect of electrode material on the generation of oxidants and microbial inactivation in the electrochemical disinfection processes

Electrochemical disinfection has gained increasing attention as an alternative for conventional drinking water treatment due to its high effectiveness and environmental compatibility. The most common method of electrochemical disinfection is the use of electro-generated oxidants, such as active chlorine and reactive oxygen species, as disinfectants. This study examined the role of electrode material on the generation of oxidants, and elucidated the different reaction pathways for generating individual oxidants by employing boron-doped diamond (BDD), Ti/RuO2, Ti/IrO2, Ti/Pt–IrO2, and Pt as anode materials. The efficiency of OH production, as determined by para-chlorobenzoic acid (pCBA) degradation, was in the order of BDD ≫ Ti/RuO2 ≈ Pt. No significant production of OH was observed at Ti/IrO2 and Ti/Pt–IrO2. The OH was found to play a key role in O3 generation at BDD, but not at the other electrodes. The production of active chlorine was in the order of Ti/IrO2 > Ti/RuO2 > Ti/Pt–IrO2 > BDD > Pt. The large difference in this order from that of ROS was attributed to the difference in the electrocatalytic activity of each electrode material toward the production of active chlorine, as evidenced by linear sweep voltammetry (LSV) measurements. In addition, the characteristics of microbial inactivation as a function of electrode material were examined under the presence of an inert electrolyte, using Escherichia coli as an indicator microorganism.