Sulfamethoxazole degradation by alpha-MnO2/periodate oxidative system: Role of MnO2 crystalline and reactive oxygen species

• Published in: Environmental science and pollution research international 2022-06, Vol.29 (29), p.44732-44745
• Main Authors: Wang, Zhijie, Bao, Jianguo, Du, Jiangkun, Luo, Liting, Xiao, Guangfeng, Zhou, Ting
• Format: Article
• Language: English
• Subjects: Antibiotics; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Contaminants; Crystal structure; Crystallinity; Earth and Environmental Science; Ecotoxicology; Electron paramagnetic resonance; Electron spin resonance; Energy efficiency; Environment; Environmental Chemistry; Environmental cleanup; Environmental Health; Environmental science; Hydroxylation; Manganese; Manganese dioxide; Metal oxides; Oxidation; Oxidation process; Pollutants; Radicals; Reactive oxygen species; Research Article; Singlet oxygen; Sulfamethoxazole; Sulfonamides; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-022-18901-z

Pollutant degradation via periodate ( IO 4 - ) and transitional metal oxides provides an economical, energy-efficient way for chemical oxidation process in environmental remediation. However, catalytic activation of periodate by manganese dioxide and the associated mechanism were barely investigated. In this study, four MnO 2 polymorphs (α-, β-, γ- and δ-MnO 2 ) were synthesized and tested to activate IO 4 - for the degradation of sulfamethoxazole (SMX). The reactivity of different MnO 2 structures followed the order of α-MnO 2  > β-MnO 2  > γ-MnO 2  > δ-MnO 2 , suggesting that the particular crystalline structure in α-MnO 2 would exhibit higher activities via IO 4 - activation. Herein, in α-MnO 2 / IO 4 - system, 91.1% of SMX was eliminated within 30 min with degradation rate constant of 0.0649 min −1 , and the neutral pH exhibited higher efficiency in SMX degradation compared with acidic and alkaline conditions. Singlet oxygen ( 1 O 2 ) was unveiled to be the dominant ROS according to the results of electron paramagnetic resonance, chemical probes and radical quenching experiments, whereas O 2 ∙ - and • OH were mainly acted as a free-radical precursor. Six oxidation products were identified by LC–MS, and the elimination of sulfonamide bond, hydroxylation and direct oxidation were found to be the important oxidation pathways. The study dedicates to the mechanistic study into periodate activation over alpha-MnO 2 and provides a novel catalytic activation for selective removal in aqueous contaminants.