Redox-Active Polymers as Robust Electron-Shuttle Co-Catalysts for Fast Fe3+/Fe2+ Circulation and Green Fenton Oxidation

Environmental Science & Technology, vol. 57, pp. 3334–3344

Abstract

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.

Authors 14

1. Hongyu Zhou

   Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering · The University of Adelaide

   Affiliation as printed

   Sichuan University , , ,

   The University of Adelaide , , , ,

   School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia

   Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

   State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China

2. Jiali Peng

   Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering

   Affiliation as printed

   Sichuan University , , ,

   Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

   State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China

3. Xiaoguang Duan corresponding

   The University of Adelaide

   Affiliation as printed

   The University of Adelaide , , , ,

   School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia

4. Haoxiang Yin

   Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering

   Affiliation as printed

   Sichuan University , , ,

   Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

   State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China

5. Bingkun Huang

   Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering

   Affiliation as printed

   Sichuan University , , ,

   Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

   State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China

6. Chenying Zhou

   Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering

   Affiliation as printed

   Sichuan University , , ,

   Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

   State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China

7. Shuang Zhong

   The University of Adelaide

   Affiliation as printed

   The University of Adelaide , , , ,

   School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia

8. Heng Zhang

   Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering

   Affiliation as printed

   Sichuan University , , ,

   Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

   State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China

9. Peng Zhou

   Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering

   Affiliation as printed

   Sichuan University , , ,

   Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

   State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China

10. Zhaokun Xiong

    Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering

    Affiliation as printed

    Sichuan University , , ,

    Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

    State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China

11. Zhimin Ao

    Beijing Normal University · Beijing Normal University, Zhuhai

    Affiliation as printed

    Advanced Interdisciplinary Institute of Environment and Ecology Beijing Normal University , ,

    Advanced Interdisciplinary Institute of Environment and Ecology Beijing Normal University, Zhuhai 519087, China

12. Shaobin Wang

    The University of Adelaide

    Affiliation as printed

    The University of Adelaide , , , ,

    School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia

13. Gang Yao Aachen Institute of Environmental Engineering

    RWTH Aachen University

    Affiliation as printed

    RWTH Aachen University , , ,

    Institute of Environmental Engineering, RWTH Aachen University, Aachen 52074, Germany

14. Bo Lai corresponding

    Sichuan University · State Key Laboratory of Hydraulics and Mountain River Engineering

    Affiliation as printed

    Sichuan University , , ,

    Sino-German Centre for Water and Health Research, Sichuan University, Chengdu 610065, China

    State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, China