Variable activity and selectivity for electrochemical oxidation wastewater treatment using a magnetically assembled electrode based on Ti/PbO2 and carbon nanotubes

• A modular anode architecture was organized by magnetic force. • Carbon nanotubes were used as the auxiliary electrodes. • The high-quality active sites were significantly increased. • The structure-activity-selectivity of the anode was variable. Magnetic multi-walled carbon nanotubes (CNTs) were loaded on Ti/PbO 2 electrode by a magnet in this study to improve the efficiency of electrochemical oxidation wastewater treatment (EOWT). These physically attached carbonaceous small granules worked as additional modules, giving the newly created electrode unique characteristics. Series of electrodes’ electrochemical properties, as well as their electrochemical oxidation performances against the azo dye acid red G, phenol, and real petrochemical wastewater, were studied. These carbonaceous granules improved the electrode's electroactivity as well as the affinity between the organics and the electrode. More importantly, the amount of CNTs loaded had a strong influence on the degrading efficiency and selectivity towards various target contaminants as well as their intermediate products in treating synthetic or real wastewaters. Lower CNTs loading resulted in heterogeneous electrode properties, whereas higher CNTs loading resulted in the new electrode acting as a porous carbonaceous electrode. The deeper operating mechanism of the new magnetically assembled electrode were discussed based on both the experiment results and multiphysics simulation.