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

Abstract

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 of organic matters in the wastewater under solar light irradiation.