High-capacity and selective removal of perfluorooctanoic acid by magnetic chitosan-based molecularly imprinted polymers

Perfluorooctanoic acid (PFOA), a representative "forever chemical," poses significant threats to ecosystems and human health due to its persistence and bioaccumulation. While molecularly imprinted polymers (MIPs) offer selectivity for PFOA removal, their practical application is often hindered by low adsorption capacity and difficulties in separation. To address these limitations, this study developed a novel magnetic chitosan-based molecularly imprinted polymer (MMIP) via a surface molecular imprinting strategy. The synthesized MMIP utilized magnetic chitosan as a support and employed a dual-functional monomer system (methacrylic acid and chitosan) to enhance adsorption sites. Characterization confirmed the material's superparamagnetism, uniform porous structure, and crystalline stability. The adsorption process followed a Pseudo-second-order kinetic model and the Langmuir isotherm model, suggesting monolayer chemisorption as the primary adsorption mechanism with the synergy of electrostatic interactions and hydrogen bonding. The MMIP exhibited a high saturation adsorption capacity of 51.28 mg g-1 and a significant imprinting factor of 2.65, demonstrating excellent selectivity for PFOA even in the presence of structural analogs. Furthermore, the material retained over 90% of its adsorption capacity after five cycles, proving its robust reusability. This work highlights the potential of the designed MMIP as a highly efficient, selective, and easily separable adsorbent for the remediation of PFOA-contaminated water.