Micelles inhibit electro-oxidation degradation of nonylphenol ethoxylates

Nonylphenol ethoxylates (NEPOs) are widely used as nonionic surfactant in the industry, which pose a threat to environment and human health. In this study, we conducted kinetic experiments and chemical analysis to investigate the effects of NEPOs micelles on degradation kinetics and electro-oxidation degradation mechanism. The electro-oxidation degradation of NEPOs followed pseudo-first order kinetics and more than 92% of NEPOs was degraded. Furthermore, the hydroxyl radicals generated by the Ti4O7 anode contributed to 41% of degradation performance. During the entire degradation process, the micelles of NEPOs undergo growth, and the steric hindrance phenomenon of micelles prevents NEPOs from being attack by hydroxyl radicals. As the results of the oxygen substituents destruction on the benzene ring and the generation of various lengths of ethoxylated chains, the Caryl-Oether bond of NEPOs was inferred as the oxidation preferential site. This study may broaden the understanding of how surfactant micelles affect advanced oxidation processes and improve the application prospects of electro-oxidation in the treatment of wastewater containing NEPOs.