Efficient degradation of perfluorooctanoic acid by electrospun lignin-based bimetallic MOFs nanofibers composite membranes with peroxymonosulfate under solar light irradiation

Perfluorooctanoic acid (PFOA) has demonstrated potential toxicity to human health and has been detected in different environmental matrices due to its stable physical and chemical properties. To degrade PFOA under solar light irradiation, we fabricated a lignin/polyvinyl alcohol (PVA)/Co/Fe metal-organic frameworks (lignin/PVA/bi-MOFs) composite membrane via a typical electrospinning and in-situ solvothermal method for the catalytic degradation of PFOA. In the peroxymonosulfate (PMS)/membranes/solar light system, Electron paramagnetic resonance analysis (EPR) demonstrated the sulfate radicals (SO₄⁻) and hydroxyl radicals (OH) were generated by activating PMS with transition metal and solar light irradiation. Lignin/PVA/bi-MOFs showed outstanding performance in that 89.6% of PFOA was degraded within 3 h under optimal conditions. Compared with that in solar light, only 59.6% PFOA was degraded in the dark, and the rate constant of PFOA degradation decreased from 0.0150 min⁻¹ to 0.0046 min⁻¹. Moreover, lignin/PVA/bi-MOFs were reused after simply rinsing with ultra-pure water and the degradation capacity of lignin/PVA/bi-MOFs remained at 77% after 4 cycles. The results might provide a new concept for the design of bimetallic MOFs for applications in organic pollutant removal.