Abstract
Coagulation is one of the most common treatment processes for the removal of contaminants from water, representing ‘the first line of defence’ for drinking water safety. However, the macroscopic and descriptive theories of trivalent metal-based coagulation have limited the optimization of its performance in the removal of natural organic matter species, which are major precursors of hazardous disinfection by-products. In this study, we have extended the coagulation theory to the functional group level, highlighting the fundamental importance of η-H2O and η-OH groups on aluminium precipitates, and finding that the selectivity for natural organic matter during coagulation is determined by their functional groups. Drawing upon the fundamental characteristics of coagulants and organic substances, this study has elucidated their behaviour during the coagulation process and offers valuable theoretical insights to guide future applications of coagulation in practical settings.
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The data supporting the findings of this study are available within the paper and its Supplementary Information.
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Acknowledgements
This work was financially supported by the Key Research and Development Plan of the Chinese Ministry of Science and Technology (grant no. 2019YFC1906501, W.Y.) and Beijing Natural Science Foundation (grant no. JQ21032, W.Y.).
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W.Y., N.G. and M.E. designed the experiments. M.L. completed the main experiments and wrote the first draft of the paper. W.Y., N.G., J.G. and M.E. made the final revisions to the paper.
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Nature Water thanks Gregory Korshin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Supplementary Notes 1–6, Figs. 1–16, and Tables 1 and 2.
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Liu, M., Graham, N., Gregory, J. et al. Towards a molecular-scale theory for the removal of natural organic matter by coagulation with trivalent metals. Nat Water 2, 285–294 (2024). https://doi.org/10.1038/s44221-024-00212-x
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DOI: https://doi.org/10.1038/s44221-024-00212-x