Enhanced degradation of humic acid by Co3O4/NCDs/PVDF photo-Fenton catalytic system

Humic acid (HA), a widely prevalent natural organic matter in aquatic environments, poses serious health risks due to its potential to form carcinogenic by-products during water treatment. While the photo-Fenton process can be employed for HA degradation, its effectiveness is often hindered by the poor catalytic performance of conventional catalysts. In this study, Co 3 O 4 was modified with nitrogen-doped carbon quantum dots (NCDs) and immobilized on a PVDF membrane. Compared with Co 3 O 4 /PVDF, Co 3 O 4 /NCDs/PVDF system achieved 85.1 % HA removal and 66 % mineralization within 60 min through photocatalytic peroxymonosulfate (PMS) activation as well as showed excellent stability in cycle experiments. The incorporation of NCDs enhanced the synergistic effect between light and PMS, improved light absorption due to the narrowed bandgap of Co 3 O 4 /NCDs/PVDF, and played a significant role in generating the primary reactive species, 1 O 2 . Additionally, Co 3 O 4 /NCDs/PVDF effectively controlled Co ions leaching. Finally, the degradation intermediates were identified, and the degradation pathways were proposed. The photo-Fenton degradation of HA preferentially broke unsaturated bonds and degraded aromatic ring compounds. The Co 3 O 4 /NCDs/PVDF photo-Fenton catalytic system serves as an effective approach for boosting the efficiency of photo-Fenton degradation.