One-step modification of MIL-88A(Fe) enhanced electro-Fenton coupled membrane filtration system for the removal of bisphenol A

Abstract

An electro-Fenton coupled membrane filtration system (abbreviated as EF-MF system) was constructed for the efficient removal of bisphenol A (abbreviated as BPA, a kind of pharmaceuticals and personal care products, abbreviated as PPCPs). In the EF-MF system, a porous Fe3O4/FeO/Fe@C catalyst was synthesized and applied to enhance the electro-Fenton reaction, and polyvinylidene fluoride/carbon fiber cloth composite cathode membrane was used as both cathode electrode and membrane. Characterization results indicated the porous Fe3O4/FeO/Fe@C catalyst exhibited micron-level rod morphology and was in an encapsulated structure with Fe3O4/FeO/Fe composite nanoparticles covered by porous graphitic carbon. Degradation experiments indicated the EF-MF system exhibited great removal efficiency (approximately 96.97%) towards BPA within 70 min in the conditions of catalyst dosing at 0.500 g·L−1, the value of pH at 3 and the current density at 0.67 mA cm−2. Quenching experiments verified both OH radical and O2− radical played significant roles in the decomposition of BPA. The mass formation of reactive oxygen radicals was mostly owing to the easy access of H2O2 to the activated sites of the porous Fe3O4/FeO/Fe@C catalyst through the porous structure and the rapid cycle conversion between zero-valent iron (ZVI), Fe(Ⅱ) and Fe(Ⅲ). Based on the results of intermediates identification, three possible decomposition pathways were presented. Toxicity analysis exhibited most of the intermediates were in less toxicity than BPA. Moreover, the EF-MF system exhibited good stability after four-cyclic utilization. This work provides an efficient and energy-saving strategy for the removal of PPCPs.