PAN/PVP/CD-MOF composite beads as an adsorbent for the removal of perfluorooctanoic acid in water

Perfluorooctanoic acid (PFOA), a persistent and bioaccumulative contaminant, poses significant challenges for water treatment due to its chemical stability and amphiphilic structure. This study reports the development of PAN/PVP/CD-MOF composite beads as a structured adsorbent integrating polymer stability with cyclodextrin-based host–guest recognition. The composite exhibits a hierarchical porous architecture that promotes rapid mass transfer and accessibility of adsorption domains despite a low BET surface area. Response surface methodology identified an optimal composition of 8 wt.% CD-MOF, 5.26 wt.% PVP, and 10 wt.% PAN. Adsorption is strongly governed by initial concentration and its interaction with adsorbent dose, while pH and contact time show minimal influence, indicating rapid equilibration and weak electrostatic dependence. Kinetic analysis reveals a coupled diffusion mechanism dominated by intraparticle transport with secondary boundary layer effects. Thermodynamic results confirm a spontaneous and entropy-driven process associated with desolvation and inclusion complex formation. The adsorption mechanism is governed by hydrophobic inclusion of the fluorinated chain within cyclodextrin cavities, complemented by hydrogen bonding and dipole interactions with the polymer matrix. These findings demonstrate that polymer-supported cyclodextrin frameworks provide an effective platform for selective and stable removal of PFOA from aqueous systems. • PAN/PVP/CD-MOF beads enable high PFOA adsorption capacity. • Cyclodextrin inclusion governs selective fluorinated chain capture. • Hierarchical pores enhance diffusion and site accessibility. • Adsorption is spontaneous and entropy-driven mechanism. • Strong CD-MOF–PAN synergy controls adsorption performance.