Efficient decontamination of organic pollutants under high salinity conditions by a nonradical peroxymonosulfate activation system

• Published in: Water research (Oxford) Vol. 191; p. 116799
• Main Authors: Chen, Fei, Liu, Lian-Lian, Chen, Jie-Jie, Li, Wen-Wei, Chen, You-Peng, Zhang, Ying-Jie, Wu, Jing-Hang, Mei, Shu-Chuan, Yang, Qi, Yu, Han-Qing
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2021
• Subjects: bisphenol A; catalysts; Decontamination; density functional theory; electrochemistry; electron transfer; Environmental Pollutants; Fe(V)=O; High salinity; Nonradical pathway; oxidation; Peroxides; Peroxymonosulfate; pollutants; saline water; Salinity; singlet oxygen; wastewater; wastewater treatment; Water treatment; High salinity; Water treatment; Nonradical pathway; Peroxymonosulfate; Fe(V)=O
• ISSN: 0043-1354; 1879-2448; 1879-2448
• DOI: 10.1016/j.watres.2020.116799

•Fe and O codopants substantially accelerated the electron transfer of g-C3N4 for PMS activation.•Efficient BPA removal was achieved at high salinity and within wider pH ranges.•High-valent iron-oxo species and singlet oxygen were identified as two main reactive species.•Nonradical pathways were elucidated based on experimental and theoretical analyses. Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) for wastewater treatment have recently attracted widespread interests. However, the degradation of organic pollutants via traditional radical-dominated pathway is severely limited by the side reactions between radicals and the co-existing inorganic anions, especially under high salinity conditions. Herein, an efficient Fe/O co-doped g-C3N4nanosheet catalyst was synthesized to dominantly activate PMS through a dual non-radical pathway with the singlet oxygen and high-valent iron-oxo species (Fe(V)=O). The rapid degradation of model pollutant bisphenol A (BPA) was achieved by dosing PMS (1 mM), catalyst (0.1 g/L) in a simulated high-salt wastewater (≥200 mM) of the developed Fe/O-doped g-C3N4+PMS system with a reaction rate constant of 1204-fold higher than that in g-C3N4+PMS system. The O and Fe co-dopants could reconfigurate the electronic structure of pristine g-C3N4 to produce more non-radical active species. The formed Fe(V)=O played a main role in the BPA degradation by promoting electron transfer from BPA molecule to the “metastable PMS/catalyst complex”, which was verified by electrochemical tests and density functional theory calculations. The auxiliary transient productions of ·OH+SO4·– species were also favorable for the pollutant degradation. Excellent reusability in a wide pH range confirmed the practical application prospects of the Fe/O-doped g-C3N4+PMS system. The successive addition of PMS with a low dosage into the system rich in pollutants was confirmed to favor the PMS utilization. Our work unveils the potential applications of a non-radical dominated process for the decontamination of organic pollutants in saline water.