Electrochemical degradation of m-nitrophenol using an innovative zeolite modified PbO2 anode: Electrode characterization, influence factors and degradation mechanism

In this study, a zeolite-doped PbO2 (Zeo-PbO2) anode was fabricated via electrodeposition technology for electrochemical oxidation of m-nitrophenol (m-NP). The results of characterization revealed that doping zeolite efficiently promoted the oxygen evolution potential and active sites of PbO2 anode, thereby higher performance to generate center dot OH radical and degrade the m-NP. The center dot OH radical was confirmed to be the primary contributor to the electrochemical oxidation of m-NP by scavenging tests. Thus, the effect mechanism of current density, supporting electrolyte, and initial pH on the removal of m-NP in the electrochemical oxidation process was explored by the generation of center dot OH radicals at different conditions. Based on the vulnerable sites of m-NP to the attack of center dot OH radical supposed by the theoretical calculation and degradation intermediates identified by GC-MS and IC, the degradation pathways of m-NP in the electrochemical oxidation process were speculated. Besides, the good recyclability and stability of Zeo-PbO2 anode were exhibited in consecutive m-NP degradation, center dot OH generation experiments, and accelerated life tests.