Redox-Active Polymers as Robust Electron-Shuttle Co-Catalysts for Fast Fe³⁺/Fe²⁺ Circulation and Green Fenton Oxidation
Date
2023
Authors
Zhou, H.
Peng, J.
Duan, X.
Yin, H.
Huang, B.
Zhou, C.
Zhong, S.
Zhang, H.
Zhou, P.
Xiong, Z.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Environmental Science and Technology, 2023; 57(8):3334-3344
Statement of Responsibility
Hongyu Zhou, Jiali Peng, Xiaoguang Duan, Haoxiang Yin, Bingkun Huang, Chenying Zhou, Shuang Zhong, Heng Zhang, Peng Zhou, Zhaokun Xiong, Zhimin Ao, Shaobin Wang, Gang Yao, and Bo Lai
Conference Name
Abstract
Accelerating the rate-limiting Fe3+/Fe2+ circulation in Fenton reactions through the addition of reducing agents (or co-catalysts) stands out as one of the most promising technologies for rapid water decontamination. However, conventional reducing agents such as hydroxylamine and metal sulfides are greatly restricted by three intractable challenges: (1) self-quenching effects, (2) heavy metal dissolution, and (3) irreversible capacity decline. To this end, we, for the first time, introduced redox-active polymers as electron shuttles to expedite the Fe3+/Fe2+ cycle and promote H2O2 activation. The reduction of Fe3+ mainly took place at active N-H or O-H bonds through a proton-coupled electron transfer process. As electron carriers, H atoms at the solid phase could effectively inhibit radical quenching, avoid metal dissolution, and maintain long-term reducing capacity via facile regeneration. Experimental and density functional theory (DFT) calculation results indicated that the activity of different polymers shows a volcano curve trend as a function of the energy barrier, highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap, and vertical ionization potential. Thanks to the appropriate redox ability, polyaniline outperforms other redox-active polymers (e.g., poypyrrole, hydroquinone resin, poly(2,6-diaminopyridine), and hexaazatrinaphthalene framework) with a highest iron reduction capacity up to 5.5 mmol/g, which corresponds to the state transformation from leucoemeraldine to emeraldine. Moreover, the proposed system exhibited high pollutant removal efficiency in a flow-through reactor for 8000 bed volumes without an obvious decline in performance. Overall, this work established a green and sustainable oxidation system, which offers great potential for practical organic wastewater remediation.
School/Discipline
Dissertation Note
Provenance
Description
Published: February 3, 2023
Access Status
Rights
© 2023 American Chemical Society