Per - and polyfluoroalkyl substances (PFAS) are highly harmful substances known as “forever chemicals” due to their resistance to degradation and their persistence in the environment. Many compounds in this class, such as perfluorooctanoic acid (PFOA), are also highly toxic to humans. We investigated the harvesting efficiency of accumulated PFOA from freshwater samples using zirconium-based metal-organic framework (MOF), i.e. UiO-66, as the primary adsorbent with a high chemical affinity for PFOA. To improve MOF stability and applicability, the UiO-66 gel was mixed with biodegradable polycaprolactone (PCL) at concentrations of 0 (pure PCL control), 5, 12, 21 and 35 wt%, respectively, and an electric field was used to electrospin a fibrous composite material (PCL-UiO-66). Gravity-driven filtration experiments using PFOA-contaminated water (2.36 mM solution) were performed to understand the correlation between the UiO-66 content in PCL-UiO-66 and the PFOA harvesting efficiency. The PFOA uptake increases linearly with the concentration of UiO-66 incorporated in the composite, achieving a maximum of ~57% using 35 wt% UiO-66 and a single-pass filtration process. Post-filtration fluorine content in the membranes confirms effective PFOA uptake of the PCL-UiO-66. Moreover, batch-soaking experiments showed that ~90% of PFOA was removed after 16 h soaking time. Here, PFOA uptake vs UiO-66 content follows an exponential trend, reaching saturation at ≧ 21 wt% of UiO-66. Stability and recyclability of the PCL-UiO-66 nanofibers have been assessed. Regenerated mats were subsequently used in a second batch soaking experiment under identical conditions and show now indication of performance loss or any signs of degradation. These results demonstrate the applicability of fibrous PCL-UiO-66-based filters for the highly efficient removal of PFOA traces from freshwater as a scalable water treatment technology using biodegradable materials. We fabricated biodegradable PCL nanofibers via electrospinning of UiO-66 MOF for the removal of perfluorooctanoic acid (PFOA) from water. Increasing MOF loading increased the adsorption capacity to ~35 mg g −1 . Batch soaking outperformed single-pass filtration due to equilibrium control. These hybrid membranes offer a sustainable, high-efficiency platform for PFAS remediation.
Palma et al. (Sun,) studied this question.