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Redox-neutral electrochemical decontamination of hypersaline wastewater with high technology readiness level

Nature Nanotechnology (2024)Cite this article

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Abstract

Industrial hypersaline wastewaters contain diverse pollutants that harm the environment. Recovering clean water, alkali and acid from these wastewaters can promote circular economy and environmental protection. However, current electrochemical and advanced oxidation processes, which rely on hydroxyl radicals to degrade organic compounds, are inefficient and energy intensive. Here we report a flow-through redox-neutral electrochemical reactor (FRER) that effectively removes organic contaminants from hypersaline wastewaters via the chlorination–dehalogenation–hydroxylation route involving radical–radical cross-coupling. Bench-scale experiments demonstrate that the FRER achieves over 75% removal of total organic carbon across various compounds, and it maintains decontamination performance for over 360 h and continuously treats real hypersaline wastewaters for two months without corrosion. Integrating the FRER with electrodialysis reduces operating costs by 63.3% and CO2 emissions by 82.6% when compared with traditional multi-effect evaporation-crystallization techniques, placing our system at technology readiness levels of 7–8. The desalinated water, high-purity NaOH (>95%) and acid produced offset industrial production activities and thus support global sustainable development objectives.

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Fig. 1: Electrochemical systems for recovering resources from hypersaline wastewaters.
Fig. 2: Bench-scale FRER effectively decomposes various organic compounds.
Fig. 3: Identification and quantification of various radicals in FRER.
Fig. 4: Radical–radical cross-coupling removes TOC in FRER.
Fig. 5: The FRER is sufficiently stable for extended operation.
Fig. 6: Field application of FRER-ED.

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Data availability

All data generated for this study are available in the Article and Supplementary Information. Source experimental data are available from figshare repository at https://doi.org/10.6084/m9.figshare.25390759 (ref. 51).

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Acknowledgements

We acknowledge the National Natural Science Foundation of China (grants 52221004 to H.L., 22022606 to G. Zhang), X. Li and J. Lin from Beijing Capital Eco-Environment Protection Group Co., Ltd. for supporting this project and M.Z. Li from Huaibei GO-ON Power Co., Ltd. for supporting our field experiment. We thank Q. Liu from the Department of Chemistry, Tsinghua University, for discussions on the mechanisms of catalysis and electrochemical measurements. We also thank S. Qu from Beijing Institute of Technology for supporting LCA analysis. We thank A.L. Chun of Science Storylab for critically reading and editing the paper.

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Author notes

  1. These authors contributed equally: Gong Zhang, Yongqi Li, Chenxuan Zhao.

Authors and Affiliations

  1. Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, China

    Gong Zhang, Yongqi Li, Jiabao Gu, Yanfeng Shi, Qi Zhou, Qingbai Chen, Qinghua Ji, Jiuhui Qu & Huijuan Liu

  2. School of Hydraulic and Hydropower Engineering, North China Electric Power University, Beijing, China

    Yongqi Li & Feng Xiao

  3. Shanghai Key Laboratory of Magnetic Resonance, State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai, China

    Chenxuan Zhao

  4. Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, China

    Gang Zhou

  5. College of Environment and Resources, Guangxi Normal University, Guilin, China

    Wen-jie Fu

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Contributions

H.L. directed the project. G. Zhang designed the experiments. G. Zhang and Y.L. synthesized the materials and performed the bench-scale degradation and electrochemical experiments. G. Zhang and C.Z. analysed results of in situ EPR experiments. J.G., Y.L. and Q.C. performed the on-site field experiments. G. Zhou carried out the DFT calculations. W.-J.F. and Y.L. collected and analysed the HRMS data. Q.Z. and Y.L. conducted the LCA analysis. G. Zhang, Y.S., Y.L. and H.L. co-wrote the Article. H.L., Q.J., F.X. and J.Q. revised the Article. All authors discussed the results and commented on the Article.

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Correspondence to Huijuan Liu.

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Nature Nanotechnology thanks Yang Yang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–39, Discussion and Tables 1–8.

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Zhang, G., Li, Y., Zhao, C. et al. Redox-neutral electrochemical decontamination of hypersaline wastewater with high technology readiness level. Nat. Nanotechnol. (2024). https://doi.org/10.1038/s41565-024-01669-3

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