Benzene ring-driven metal hydrolysis and floc formation in coagulation: mechanistic insights from organic structural units
File(s)
Accepted version
Author(s)
Zhu, Jian
Graham, Nigel
Li, Guibai
Gregory, John
Yu, Wenzheng
Type
Journal Article
Abstract
The chemical structure of natural organic matter (NOM) is known to influence its removal during coagulation, yet the underlying molecular-scale mechanisms remain elusive. This has limited the rational design of advanced water treatment processes. Here, we reveal a previously overlooked mechanism, the cation–π interaction, as a key driver for the efficient removal of aromatic organic matter. Using model compounds with and without a benzene ring (benzoate/phthalate vs acetate), we demonstrate that the benzene ring is not merely a passive scaffold but an active participant in coagulation. It acts as an initial anchor, attracting trivalent metal ions via strong cation–π interactions. This initial attraction then facilitates a more stable, secondary binding as functional groups (e.g., –COOH and –OH) on the ring chelate with the metal ions, ultimately promoting floc growth. This dual-binding mechanism, supported by spectroscopic and microscopic evidence, explains how the presence of a benzene ring participates in metal ion hydrolysis and floc formation, leading to significantly improved coagulation performance. This finding highlights the critical role of aromatic structures in the coagulation process and provides a new theoretical foundation for optimizing coagulants to achieve the selective and efficient removal of specific aromatic pollutants.
Date Issued
2025-11-18
Date Acceptance
2025-10-31
Citation
Environmental Science and Technology, 2025, 59 (45), pp.24619-24630
ISSN
0013-936X
Publisher
American Chemical Society
Start Page
24619
End Page
24630
Journal / Book Title
Environmental Science and Technology
Volume
59
Issue
45
Copyright Statement
Copyright © 2025 American Chemical Society. This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/41191512
Subjects
benzene rings
cation–π interaction
coagulation
floc formation
metal-ion hydrolysis
natural organic matter
Hydrolysis
Benzene
Metals
Water Purification
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2025-11-05