Tuning halides recognition via side chain engineering in magnetically composite for DBP precursors capture

Large-scale water treatment facilities in both coastal and inland regions worldwide face significant challenges posed by disinfection byproducts (DBPs) arising from excessive iodide (I⁻) and bromide (Br⁻) concentrations. Herein, we report the development of a magnetic composite with tailored side chains (AQBP) for the precise recognition of I⁻ and Br⁻ in complex aquatic environments. Comparative evaluation of AQBP against the control composite (PSMP) and two commercially available resins (MIEX and D201) highlights the precise sequestration of I⁻ and Br⁻ by AQBP across various complex aquatic matrices. Notably, AQBP maintains a removal efficiency exceeding 80% for trace precursors even when competing anion concentrations are 10³-fold higher, and continues to demonstrate excellent capture performance in real coastal estuarine water samples. The elongated alkyl chains and densely packed aromatic architecture within the AQBP synergistically enhance hydrophobicity, conferring superior selectivity for the highly hydrophobic I⁻ and Br⁻. The abundant quaternary ammonium groups on AQBP significantly enhance electrostatic attraction toward target halides. Theoretical calculations further substantiate the strong non-covalent interactions between AQBP and I⁻ and Br⁻. Collectively, these findings confirm that AQBP represents an innovative and cost-effective solution for the precise capture of I⁻ and Br⁻ in large-scale water treatment applications, offering considerable promise for improving drinking water safety.