Cetyltrimethylammonium Bromide Assisted Synthesis of Honeycombed Iohexol-Microporous Organic Network for Efficient Membrane Removal of 2,4-Dichlorophenol from Wastewater Samples

The development of functionalized microporous organic networks (MONs) with low-cost monomers, tailored morphology, and practical processability remains a significant challenge for the advancement of MONs and their application in wastewater treatment. Herein, we report the first example of a cetyltrimethylammonium bromide (CTAB)-assisted synthesis of a honeycombed iohexol-based MON (H-IH-MON-2%) using a low-cost commercial contrast agent, iohexol, through the Sonogashira−Hagihara coupling reaction; this material is further integrated into an electrospun polyacrylonitrile (PAN) nanofiber membrane via electrospinning for the efficient removal of 2,4-dichlorophenol (2,4-DCP) from aqueous environments. As a result, iohexol serves as an inexpensive monomer and provides the MON with abundant hydroxyl and amide groups, while the introduction of CTAB effectively mitigates particle aggregation, yielding a well-defined honeycomb-like morphology with enhanced specific surface area of 176.6 m2 g−1 and a narrowed pore size of 1.2 nm. The resulting H-IH-MON-2% exhibits exceptional adsorption performance, achieving a maximum nonlinear Langmuir adsorption capacity of 531.2 mg g−1 for 2,4-DCP, with ultrafast kinetics (<10 min at an initial concentration of 10 mg L−1). The H-IH-MON-2%@PAN membrane not only overcomes the recovery limitations of powdered adsorbents but also demonstrates a high retention rate (>99%) and excellent reusability. Mechanistic studies, supported by XPS and FT-IR, reveal that the adsorption is governed by synergistic hydrogen bonding, π−π interactions, and hydrophobic effects. This work presents a promising strategy for constructing functionalized MON-based membranes, highlighting their substantial potential for the practical remediation of phenolic pollutants in complex water matrices.