CoFe2O4-titanium hollow fiber membrane filtration coupling peroxymonosulfate activation for water purification: Preparation, performance and mechanism

Constructing membrane filtration coupled with peroxymonosulfate (PMS) activation system has emerged as a promising strategy for efficient water purification. In this work, a novel CoFe2O4-titanium hollow fiber membrane (CoFe2O4-THFM) filtration system was proposed, aiming to integrate Co/Fe synergism and membrane filtration for enhancing PMS activation (MFPA) toward phenol (PE) removal. The performance of CoFe2O4-THFM MFPA process was rationally regulated via electro-deposition and calcination process, which displayed 100% PE removal and showed 4.80 and 1.24 times (under 2 min running time) higher than that of FeO-THFM and CoO-THFM MFPA process. Mechanism analysis revealed a non-radical-dominated oxidation mechanism (involving 1O2, Fe (VI)=O, and electron transfer), primarily attributed to the crucial role of Fe. On the one hand, the synergistic promotion mechanism of dual metal centers (Co(III)/Fe(II)) in the PMS activation process significantly enhanced the content of Co(II), and together with Fe(II) acted as active sites to generate reactive oxygen species (ROS, especially 1O2) for PE removal. On the other hand, the generated Fe (VI)=O (from Fe(III)) tend to react with PE (electron-donating), while the formed CoFe2O4-THFM-PMS* complex (oxygen vacancy (OV) mediated) plundered electrons from PE (electron transfer), leading its oxidation. The notable non-radical process (1O2, Fe (VI)=O and electron transfer) mentioned above contributed to the excellent performance in real water matrix.