Design of magnetically assembled electrode (MAE) with Ti/PbO2 and heterogeneous auxiliary electrodes (AEs): The functionality of AEs for efficient electrochemical oxidation

Abstract

Heterogeneous auxiliary electrodes (AEs, Fe3O4/Sb-SnO2 or Fe3O4/Pb3O4 granules) with different amount were loaded on foil Ti/PbO2 (main electrode, ME) and thereby formed series of so-called magnetically assembled electrode (MAE) for more efficient, flexible and versatile electrochemical oxidation (EO) treatment of organic wastewater. Diverse material characterizations and electrochemical characterizations were performed to investigate the nature of the AEs and the effects of AEs type and assembling amount on the electrochemical behaviors of the MAE, respectively. Azo dye Acid red G (ARG) and lignosulphonate (lignin) were selected as the target pollutants to examine the effects of AEs type and assembling amount on the EO performance of MAE. Results show that both two types of AEs could increase the electrochemical roughness and the active sites, but with different optimum amount. Compared with 2D Ti/PbO2, a series of MAEs exhibited about 18%-30% higher efficiency in ARG degradation, among which the MAE with higher Fe3O4/Pb3O4 AEs amount had better performance. However, in breaking lignin macromolecule structure into smaller molecules, the MAE with higher Fe3O4/Sb-SnO2 AEs amount was better. The different synergisms between the two heterogeneous AEs and the ME in EO were proposed, and the relationship of the chemical composition, structure and electrocatalytic activity of the MAEs were further revealed. Finally, stability experiment results showed that the MAEs were safe and reliable.