Investigation of catalytic self-cleaning process of multiple active species decorated macroporous PVDF membranes through peroxymonosulfate activation

Currently, carbon-based catalysts integrated with macroporous catalytic membrane have aroused considerable attention for environmental remediation because of its practicability and high efficiency. Herein, nitrogen doped carbon nanotube hybrids (Fe-Co@NC-CNTs) decorated with multiple active species (Fe₃Co₇/CoFe₂O₄@Fe/Co[sbnd]N[sbnd]C) were designed through N-molecule assisted pyrolysis of bimetallic (Fe/Co) metal–organic frameworks, and then immobilized on poly(vinylidene fluoride) (PVDF) membrane to construct macroporous Fe-Co@NC-CNTs/PVDF catalytic membrane via directional freezing technique, where active sites were efficiently exposed for oxidants and target pollutants. As expected, Fe-Co@NC-CNTs/PVDF membrane successfully achieved almost 100% bisphenol A (BPA) degradation after 40 min via PMS activation, which was significantly overperformed the majority of conventional carbon-based catalysts. Besides, we found that Fe-Co@NC-CNTs/PVDF membrane not only exhibited ideal catalytic and self-cleaning property in humic acid (HA)-BPA coexistence system, but also maintained the excellent reusability and ultrahigh water flux (10464.45 L m⁻² h⁻¹) even after 5 cycles. Notably, in EPR analysis and quenching experiments, it was found that sulfate radicals (SO₄·⁻ and ·OH) and singlet oxygen (¹O₂) participated the degradation process while ¹O₂ made a major contribution. More significantly, this study is very meaningful for the development of novel catalytic self-cleaning membranes with PMS activation.