Highly Efficient Utilization of Ferrate(VI) Oxidation Capacity Initiated by Mn(II) for Contaminant Oxidation: Role of Manganese Species

• Published in: Environmental science & technology Vol. 57; no. 6; pp. 2527 - 2537
• Main Authors: Zhao, Xiao-Na, Huang, Zhuang-Song, Wang, Gui-Jing, Liu, Yu-Lei, Song, Wei-Wei, Ma, Jun, Wang, Lu
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.02.2023
• Subjects: Acetaminophen; Bisphenol A; Contaminants; Iron; Iron - chemistry; Iron constituents; Manganese; Manganese - chemistry; Manganese ions; Natural waters; Oxidation; Oxidation-Reduction; Species; Treatment and Resource Recovery; Water Pollutants, Chemical - chemistry; oxidation efficiency; reactive manganese species; ferrate; Mn(II); micropollutants
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.2c06931

Manganese ion [Mn­(II)] is a background constituent existing in natural waters. Herein, it was found that only 59% of bisphenol A (BPA), 47% of bisphenol F (BPF), 65% of acetaminophen (AAP), and 49% of 4-tert-butylphenol (4-tBP) were oxidized by 20 μM of Fe­(VI), while 97% of BPA, 95% of BPF, 96% of AAP, and 94% of 4-tBP could be oxidized by the Fe­(VI)/Mn­(II) system [20 μM Fe­(VI)/20 μM Mn­(II)] at pH 7.0. Further investigations showed that bisphenol S (BPS) was highly reactive with reactive iron species (RFeS) but was sluggish with reactive manganese species (RMnS). By using BPS and methyl phenyl sulfoxide (PMSO) as the probe compounds, it was found that reactive iron species contributed primarily for BPA oxidation at low Mn­(II)/Fe­(VI) molar ratios (below 0.1), while reactive manganese species [Mn­(VII)/Mn­(III)] contributed increasingly for BPA oxidation with the elevation of the Mn­(II)/Fe­(VI) molar ratio (from 0.1 to 3.0). In the interaction of Mn­(II) and Fe­(VI), the transfer of oxidation capacity from Fe­(VI) to Mn­(III), including the formation of Mn­(VII) and the inhibition of Fe­(VI) self-decay, improved the amount of electron equivalents per Fe­(VI) for BPA oxidation. UV–vis spectra and dominant transformation product analysis further revealed the evolution of iron and manganese species at different Mn­(II)/Fe­(VI) molar ratios.