Synergistic enhancement of the adsorption performance of covalent organic framework (COF) for chlorinated organic compounds through structural connection and electronic regulation

COF-V rapidly adsorbs 2,4-DCP, CAP and DCF-Na within 30 min. • Maximum capacities of 665.54–773.65 mg∙g −1 were achieved. • Ternary mixtures exhibit a non-additive synergistic compensation effect. • Imine sites and hierarchical pores enable stable, reusable adsorption. Efficient capture of structurally diverse chlorinated organic compounds (COCs) from mixed aqueous matrices requires adsorbents that combine accessible porosity with chemically differentiated binding environments. Here, we report an imine-linked covalent organic framework, COF-V, that integrates a conjugated pore surface, imine-rich polar sites and hierarchical micro-/mesoporosity, with a Brunauer-Emmett-Teller surface area of 752.73 m 2 ∙g −1 and dominant pore sizes of 1.92 and 3.78 nm. COF-V rapidly adsorbed 2,4-dichlorophenol (2,4-DCP), chloramphenicol (CAP) and diclofenac sodium (DCF-Na), reaching equilibrium within 30 min and exhibiting Langmuir capacities of 680.84, 773.65 and 665.54 mg∙g −1 at 293 K, respectively. In binary mixtures, competition depended strongly on molecular size and functional-group complementarity. In the ternary system, however, the observed adsorption-retention ratios of 77.15 %, 94.66 % and 83.43 % exceeded those predicted from independent superposition of the corresponding binary inhibition effects, giving compensation coefficients of 1.021, 1.014 and 1.072. This non-additive synergistic compensation arises from complementary occupation of confined and wider pore domains and differentiated use of aromatic and polar binding sites, rather than from adsorption exceeding the corresponding single-solute capacities. X-ray photoelectron spectroscopy and density functional theory calculations reveal a cooperative mechanism involving pore confinement, π-π and n-π interactions, hydrophobic association, hydrogen and halogen bonding, and speciation-dependent electrostatics. COF-V preserved its characteristic framework structure after acid and alkali exposure and retained cycle stability factors above 0.85 after five regeneration cycles. These results identify pore-molecule complementarity and spatially differentiated interfacial interactions as design principles for mitigating competitive adsorption in multicomponent aqueous systems. Download: Download high-res image (230KB) Download: Download full-size image