Facile coating Co/Ca-silicate on 13X for enhanced degradation of metronidazole via peroxymonosulfate activation: Catalytic performance and toxicity evolution

A facile urea-assisted hydrothermal method was developed for synthesizing Co(Ca)-silicate nanosheets@13X (CoCa-13X) as catalyst materials for peroxymonosulfate activation. Urea gradually dissolves 13X to form the silicate anion, and anchors Co 2+ ions to the surface of 13X, while introducing Ca 2+ ions to form in situ Co/Ca-silicates. The degradation efficiency and reusability of the compound catalyst for metronidazole (MNZ) were investigated. The results demonstrated that at an initial concentration of 25 mg/L, the CoCa-13X-PMS system exhibited excellent catalytic degradation performance towards MNZ, and the degradation rate reached 99.52 % within 5 min. Furthermore, the CoCa-13X-PMS system maintained high catalytic activity against various organic pollutants and even at high concentrations of pollutants (up to 30 mg/L). Free radical quenching experiments revealed simultaneous participation of SO 4 • – and 1 O 2 in the oxidation process simultaneously. Additionally, the degradation mechanism and pathway of MNZ were studied and proposed, along with evaluation of biotoxicity associated with its degradation intermediates. This method offers a novel strategy for synthesizing silica zeolite-based cobalt catalysts with exceptional PMS activity for removal of organic pollutants.