A novel Fenton-like catalyst and peroxymonosulfate activator of Mn3O4/λ-MnO2 for phenol degradation: Synergistic effect and mechanism

• Published in: Inorganic chemistry communications 2023-04, Vol.150, p.110396, Article 110396
• Main Authors: Xing, Ziqin, Fan, Meng, Liu, Jianxin, Wang, Yawen, Zhang, Xiaochao, Li, Rui, Wang, Yunfang, Fan, Caimei
• Format: Article
• Language: English
• Subjects: Heterogeneous catalyst; Mn3O4/λ-MnO2; Peroxymonosulfate activation; Photo-Fenton-like
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2023.110396

An alcohol-thermal method was used to prepare novel Mn3O4/λ-MnO2 catalyst, which exhibited high performance in activating peroxymonosulfate for phenol degradation. For the photo-Fenton-like system, on the one hand, various valence manganese ions in Mn3O4/λ-MnO2 composite could react with peroxymonosulfate to produce hydroxyl radicals and sulfate radicals. On the other hand, the photoelectrons of Mn3O4/λ-MnO2 under visible light participated in the generation of superoxide radicals. As a result, these active radicals had synergistic effect for the degradation of phenol. [Display omitted] •A novel Mn3O4/λ-MnO2 catalyst rich in Mn2+, Mn3+ and Mn4+ various valences was successfully synthesized by an alcohol-thermal method.•The Mn3O4/λ-MnO2 catalyst was first reported as a Fenton-like catalyst for peroxymonosulfte activation for phenol removal.•The degradation of phenol in the photo-Fenton-like (Mn3O4/λ-MnO2/PMS/vis) and Fenton-like (Mn3O4/λ-MnO2/PMS/dark) systems were compared.•Controlling factors of phenol degradation in the photo-Fenton-like system were evaluated in detail.•The different phenol degradation mechanisms in the photo-Fenton-like system and Fenton-like system were proposed. A low-cost and highly efficient Fenton-like catalyst desired to produce the hydroxyl radical (·OH) and sulfate radical (SO4·-) at the same time for environmental applications was successfully fabricated via a noval alcohol-thermal method. Remarkably, the Mn3O4/λ-MnO2 composite exhibited the highly efficient activation for peroxymonosulfate (PMS) and deep mineralization for phenol under visible-light irradiation. The phenol degradation fitted the pseudo-first-order reaction kinetics well with rate constant of 0.0455 min−1 for photo-Fenton-like system and 0.0340 min−1 for Fenton-like system, respectively. Based on the results of radical quantification experiments and electron spin resonance (ESR) tests, ·OH, SO4·- and superoxide radical (·O2–) species played imperative roles during the oxidation process. The active species were mainly derived from the multivalent manganese ions on the surface of Mn3O4/λ-MnO2 composite formed a cyclic loop and reacted with HSO5- of PMS, thus significantly enhancing the catalytic performance. Finally, the probable reaction mechanism of Mn3O4/λ-MnO2 catalyst activation of PMS in a Fenton-like system under solar irradiation or in dark were speculated. This work will provide a new idea for the practical application of PMS activation in the treatment