Three-dimensional ordered mesoporous Co3O4/peroxymonosulfate triggered nanoconfined heterogeneous catalysis for rapid removal of ranitidine in aqueous solution

Peroxymonosulfate (PMS)-induced advanced oxidation processes hold great promise for the in-depth treatment of many challenging pollutants. Herein, three-dimensional ordered mesoporous Co3O4 (3D OM-Co3O4) was synthesized with a KIT-6 template to boost PMS activation for the rapid removal of a target pollutant of ranitidine (RAN). At the optimal conditions, 3D OM-Co3O4 achieved the RAN removal efficiency of 99.2% and the RAN mineralization efficiency of 63.7% within 7 min. PMS activation by 3D OM-Co3O4 involved simultaneous non-radical and radical pathways, with the latter accounting for 73.2% of the total RAN removal efficiency. Density functional theory calculations demonstrated that compared with Co3O4 nanoparticles, the adsorption energy of PMS molecules bonded to 3D OM-Co3O4 was increased from-0.213 eV to-0.297 eV due to its ordered mesoporous structure. The regeneration of 3D OM-Co3O4 by a reduction treatment indicated that its catalytic stability was associated with rapid charge transfer between the Co(III)/Co(II) redox couple. The possible degradation pathways revealed the oxidation behavior of RAN in the 3D OM-Co3O4/PMS heterogeneous system. This study provides a new perspective for the mechanism of PMS-induced heterogeneous catalytic oxidation and a novel method for enhancing the synergistic effect between Co3O4 nanoparticles.