Improvement of peroxymonosulfate utilization efficiency for sulfamethazine degradation by photo-electron activating peroxymonosulfate: Performance and mechanism

Enhancing the utilization efficiency of oxidant is of great importance for advanced oxidation processes (AOPs). Herein, nitrogen-doped titania dioxide/carbon (NTC7) catalyst was fabricated via pyrolyzing NH2-MIL-125 under nitrogen atmosphere at 700 degrees C. Excitation of NTC7 under visible light can success-fully achieve efficient activation of peroxymonosulfate (PMS) (NTC7 + PMS + Vis). Degradation perfor-mance and PMS activation mechanism were systematically investigated using sulfamethazine (SMT) as the target pollutant. It was found that the photo-generated electrons excited from NTC7 under visible light played the dominant role in enhancing the productive consumption of PMS. Its utilization increased by 66 % (D[PMS]/D[SMT] = 7.0) in NTC7 + PMS + Vis process and the degradation rate was 2.14 times higher than that of NTC7 + PMS process. The ketonic C@O groups and structural defects were responsible for the generation of 1O2 in dark activation while radicals (.OH, O2.-) were more inclined to be continu-ously produced in NTC7 + PMS + Vis process. The involved degradation pathways, intermediates, and tox-icity assessment have been studied in detail. This work provides an effective approach to enhance the utilization efficiency of oxidant for pollutant degradation by AOPs.(c) 2022 Elsevier Inc. All rights reserved.