Efficient removal of perfluorooctanoic acid by persulfate advanced oxidative degradation: inherent roles of iron-porphyrin and persistent free radicals

Perfluorooctanoic acid (PFOA) is a persistent and bioaccumulative refractory organic pollutant, which has aroused great concern on its environmental fate. Herein, inspired by biomimetic materials, a preeminent heterogeneous catalyst, iron-porphyrin loaded biochar (Fe(TPFPP)/BC) was constructed to activate persulfate (PS) for PFOA degradation. Moreover, the existence of persistent free radicals (PFRs) on biochar could transfer electrons to iron-porphyrin and PS to directly or indirectly speed up the generation of SO4-center dot and OH. By introducing ascorbic acid (AA) as an electronic circulation agent to maintain the concentration of PFRs, the Fe (TPFPP)/BC-PS-AA system could degrade 75.90% PFOA in 30 min, even reaching 90.88% with increasing reaction time. The effects of key factors on PFOA degradation were investigated. The reaction mechanism and degradation pathway were proposed as well. This work not only provides insights into the catalytic field by integrating biomimetic thought, but also provides an efficient method to degrade perfluorinated compounds (PFCs).