Insight into the binding properties of carbamazepine onto dissolved organic matter using spectroscopic techniques during grassy swale treatment

Carbamazepine (CBZ) is a worldwide anti-epileptic drug, whose fate and migration can be greatly influenced by contact with dissolved organic matter (DOM). The properties of DOM in road runoff can be greatly changed by grassy swale (GS) treatment, which influences the complexation of CBZ with DOM. Spectroscopic techniques were employed to explore the different binding properties between CBZ and DOM, and to understand the migration and biogeochemistry of CBZ. The two-dimensional correlation spectroscopy (2D-COS)demonstrated that effluent DOM displayed more binding sites for CBZ than influent DOM, and the binding sequencing of CBZ with DOM fluorophores can be greatly influenced by GS treatment. The results also suggest that protein-like materials exhibit higher log K-M values than other fluorescent components, indicating that fluorescent protein-like materials play a crucial role in the biogeochemical behavior of CBZ. Meanwhile, the log K-M values showed a remarkable increase after GS treatment. GS treatment can also remove most fluorescent DOM, reducing the risk of CBZ in the water environment.