Biogenic manganese oxide: An efficient peroxymonosulfate activation catalyst for tetracycline and phenol degradation in water

From the view of environment and easy availability, to develop the most efficient manganese oxide for peroxymonosulfate (PMS) activation is of great importance for the degradation of recalcitrant organic pollutants. In this study, biogenic manganese oxide (BioMnO(x)) exhibited an unprecedented efficiency than the most efficient 3D alpha-Mn2O3 prepared by chemical method. 100% of phenol degradation at 40 min and 99.4% of tetracycline removal at 60 min were achieved over BioMnO(x) with PMS, which was 3-fold faster than 3D alpha-Mn2O3. BioMnO(x) also has an excellent long-term stability and good performance toward the pollutants degradation at a wide pH range of 3.0-9.0. Most importantly, O-1(2) was identified as the primary reactive species in BioMnO(x)/PMS system based on the trapping experiment and EPA analysis. The PMS activation over BioMnO(x) should follow a self-decomposition and energy quenching mechanism instead of electron transfer process as confirmed by the XPS analysis. Finally, the degradation pathways of tetracycline and phenol by O-1(2) over BioMnO(x) were proposed according to HPLC and HPLC-MS results, which are greatly different from that by (OH)-O-center dot oxidation in the literature.