Enhancing hydroxyl radical production from cathodic ozone reduction during the ozone-electrolysis process with flow-through reactive electrochemical membrane cathode

In this study, a flow-through ozone-electrolysis (O 3 -electrolysis) process was developed by combining ozonation with an electrolysis using a porous reactive electrochemical membrane (REM) cathode. Due to the convection-enhanced mass transport and fast radial diffusion inside the small pores of REM cathodes, the rate of cathodic O 3 reduction to ozonide radicals (O 3 •− ) was significantly enhanced, while the further cathodic O 3 •− reduction to oxygen was inhibited during the flow-through O 3 -electrolysis process compared to the conventional mixed-tank O 3 -electrolysis process. Consequently, more hydroxyl radicals (•OH) were formed from O 3 •− decay in water during the flow-through O 3 -electrolysis process than the mixed-tank O 3 -electrolysis process. Corresponding to the higher •OH yields from cathodic O 3 reduction, the flow-through O 3 -electrolysis process substantially enhanced the abatement kinetics and efficiency of para -benzoic acid ( p CBA, a model compound of ozone-resistant micropollutant) in a groundwater than conventional ozonation and the mixed-tank O 3 -electrolysis process. These results suggest that the flow-through O 3 -electrolysis process may provide a competitive treatment technology for micropollutant abatement in water treatment .