Enhanced oxidative degradation of 4-chlorophenol via peroxymonosulfate activated by Co3Fe7 and Co0 embedded in N-doped porous carbons: Pivotal role of nitrogen-vacancy

Abstract

The incorporation of nitrogen-vacancy (NV) is an effective approach for boosting the catalytic performance. Herein, the FCCNV catalyst was developed via CoFe2O4 on the zeolitic imidazolate frameworks-67 and g-C3N4 modified with NV through the pyrolysis process involving self-reduction. Further, it was used to treat 4-chlorophenol (4-CP) through peroxymonosulfate (PMS) activation. The FCCNV/PMS system exhibited high performance for 4-CP degradation in a wide pH range of 3.0–11.0. Moreover, it also showed robust durability after five cycles without significant loss of catalytic performance or metal leaching. Quenching experiments and electron spin resonance technologies confirmed that the FCCNV/PMS system was mainly enriched in 1O2, SO4−, and OH species. After NV modification, more low-price cobalt-iron metals were encapsulated in a CN structure of the FCCNV catalyst, which remarkably improved it's stability and enhanced the degradation performance through accelerating the transformation such as Co3+/Co2+ or Fe3+/Fe2+. Furthermore, the catalytic mechanism of FCCNV and the removal pathway of 4-CP were proposed when the FCCNV/PMS system was employed. This proof-of-concept avenue for developing such a high-efficient FCCNV catalyst clarifies the in-depth effect of NV modification for effluent treatment via PMS activation.