Abstract
Per- and polyfluoroalkyl substances (PFAS) are persistent anthropogenic micropollutants that pose severe risks to ecological integrity and human health due to the extraordinary stability of their carbon–fluorine (C–F) bonds. Conventional water treatment techniques, such as granular activated carbon adsorption and membrane filtration, merely phase-transfer these contaminants without destroying them, while thermal incineration demands intensive energy inputs. In this study, we demonstrate the sustainable visible-light-driven photocatalytic degradation and defluorination of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) using engineered monoclinic bismuth vanadate (BiVO4) nanostructures. Synthesized via a facile hydrothermal route, the BiVO4 photocatalyst exhibited an optimal bandgap of 2.42 eV, enhanced surface area, and exposed high-energy crystal facets facilitating rapid charge separation. Under visible light irradiation (λ ≥ 420 nm), the BiVO4 system achieved 94.2% degradation and 76.8% defluorination of PFOA within 6 hours, following pseudo-first-order kinetics. Radical scavenging experiments and electron paramagnetic resonance spectroscopy identified photogenerated valence-band holes (h+) and reactive oxygen species as the primary drivers initiating C–F cleavage through a stepwise Kolbe-type decarboxylation and hydrodefluorination mechanism. Furthermore, the catalyst maintained robust structural stability and high catalytic efficiency across five consecutive cycles in real electroplating wastewater matrices. This work highlights BiVO4-mediated photocatalysis as an energy-efficient, environmentally benign technology for industrial wastewater decontamination.
