Insights into the pollutant electron property inducing the transformation of peroxymonosulfate activation mechanisms on manganese dioxide

• Published in: Applied catalysis. B, Environmental Environmental, 2022-11, Vol.317, p.121753, Article 121753
• Main Authors: Huang, Renfeng, Gao, Peng, Zhu, Jinyuan, Zhang, Yongqing, Chen, Yan, Huang, Shaobin, Wang, Guangzhao, Yu, Zebin, Zhao, Shuaifei, Zhou, Shaoqi
• Format: Article
• Language: English
• Subjects: Advanced oxidation process; Electron property; Mediated electron transfer; Nonradical activation mechanism; Singlet oxygen
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121753

Herein, using manganese dioxide octahedral molecular sieve (Mn-OMS) as the catalyst, we investigate how pollutant electron property affects the peroxymonosulfate (PMS) activation mechanism. More than 95% of electron-rich pollutants are degraded in the Mn-OMS/PMS system after 30 min reaction time, but oxidative decomposition of electron-poor pollutants takes at least 150 min. This difference in reaction rate is proved to be pollutant-dependent. We then combine multiple methods to cross-validate the PMS activation mechanism, including the quenching test, EPR characterization, solvent-exchange experiment, PMS decomposition rate test, and electrochemical analysis. Catalyst-mediated electron transfer is determined as the main activation mechanism for electron-rich pollutants degradation, while removal of electron-poor pollutants relies on singlet oxygen (1O2) and/or radicals. Additionally, the PMS activation mechanism depends on whether H2O or pollutants or low-valence Mn ions preferentially transfer electrons to the adsorbed PMS. This work provides mechanistic insights into the effect of pollutants type on PMS activation. [Display omitted] •Pollutant type can induce the transformation of PMS activation mechanism.•Water molecules are indispensable reactants in singlet oxygen generation.•The sources of singlet oxygen are water molecules and peroxides.