Synergistic oxidation of simazine in electro-peroxone system with enhanced in-situ electrogenerated H2O2 activity electrode: Performance and mechanism

Abstract

Conventional electrocatalytic technology is limited by the efficiency of in-situ electrogenerated H2O2 over the cathode, and the degradability for some pollutants with specific structures is poor. In this study, tert-butyl-anthraquinone modified carbon nanotube electrode (CNT/TBAQ) was used as a cathode to assess the degradation efficiency of pollutants in synergy with O3. The surface hydrophobicity of the modified electrode was improved, the proportion of oxygen-containing functional groups was increased by 4.3%, and the catalytically active sites of the material were increased. Compared with electrochemical and ozone technology, the electro-peroxone process could basically achieve complete removal of simazine within 6 min. The TOC removal rate also reached 62.3% after 120 min. Within 90 min, the H2O2 concentration of the CNT/TBAQ cathode reached 583.36 mg/L with current efficiency of 86%. During the electro-peroxone process, the H2O2 produced by electroreduction reacted with ozone to produce a large amount of •OH, which improved the mineralization of pollutants. Degradation intermediates of simazine was identified by LC-MS and detailed transformation pathways was proposed. After 10 cycles, the CNT/TBAQ cathode still maintained a strong ability to produce H2O2 and oxidize pollutants. These results indicate that CNT/TBAQ combined with O3 oxidation, can improve the pollutant degradation efficiency, providing a promising technology for trace organic pollutant abatement.