Size-selective trapping and photocatalytic degradation of PFOA in Fe-modified zeolite frameworks

Removal and destruction of perfluorooctanoic acid (PFOA) are challenging due to its extreme persistence and dilute concentrations. This study investigated dual-function adsorptive-photocatalytic zeolite materials to selectively adsorb and degrade PFOA via tuning pore structures and doping transition metals. It is found that the pore opening is critical in the size-selective trapping of PFOA, while the iron doped zeolites present excellent adsorption of PFOA (>80 mg g −1 ) combining hydrophobic and electrostatic interactions. The formation of PFOA-iron complexes has reduced bond dissociation energy of C−F, calculated from density functional theory, for favorable stepwise defluorination (over 60% defluorination in 4 hours) by superoxide radicals and ligand-to-metal charge transfer. This mechanistic investigation extends the potential of the concentrate-and-degrade concept to remove PFOA selectively and effectively from contaminated water. • Zeolites with comparable pore opening to PFOA favor its adsorption and degradation. • PFOA adsorption on Fe-BEA is driven by hydrophobic and electrostatic interactions. • PFOA molecule activation by Fe complexes decreases the decarboxylation energy. • Ligand-to-metal charge transfer and superoxide radical contribute to PFOA degradation.