Spinel-based zinc-doped Co₃O₄ (ZCO) catalytic membrane for efficient peroxymonosulfate activation and chloroquine...

The degradation of emerging contaminants (ECs) in wastewater remains a significant challenge, primarily due to the low activation efficiency and difficulty in catalyst recovery associated with traditional heterogeneous peroxymonosulfate (PMS) systems. In this study, a zinc (Zn)-doped Co₃O₄ spinel (ZCO) catalyst was designed via an atom doping strategy and immobilized onto a polyvinylidene fluoride (PVDF) membrane to construct a ZCO@PVDF catalytic membrane, thereby developing an efficient and innovative approach for ECs degradation. The innovation of this study is the Zn doping-induced electron-polarized distribution, which creates electron-rich Co centers and significantly enhances the PMS activation efficiency. The porous structure and confined space of the membrane significantly improved the exposure of active sites, facilitated interfacial mass transfer, and promoted reactant enrichment. Consequently, the ZCO@PVDF membrane/PMS system enabled the efficient filtration-based removal of Chloroquine phosphate, with the pseudo-first-order rate constant K of 0.035 ms^-1 for its removal. The system exhibited exceptional catalytic performance, achieving 99.9 % Chloroquine phosphate degradation within 30 min, with the pseudo-first-order rate constant K dominating the reaction (pH = 6.8, PMS = 1.6 mM, Chloroquine phosphate = 10 mg L^-1, Catalyst loading = 2.0 mg cm^-2). The active species responsible for the degradation of emerging pollutants in the ZCO@PVDF membrane/PMS system was SO₄·^-, ·OH, and ¹O₂. The degradation pathway and toxicity evolution of Chloroquine phosphate were identified through molecular orbital calculations, Fukui index analysis, HPLC testing, and T.E.S.T. software predictions. This immobilized catalytic membrane-based AOPs presents an innovative solution to overcome the limitations of conventional heterogeneous catalysis.