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Abstract Photocatalytic ozonation is an attractive advanced oxidation process for wastewater treatment, but highly active catalysts with strong response to visible light are urgently needed to push forward its practical application. In this study, a hierarchical biomimetic monoclinic bismuth vanadate (BiVO 4) with leaves morphology was synthesized by a hydrothermal method, and employed as catalyst for oxalic acid and penicillin degradation in photocatalytic ozonation. The results show that the organics degradation was more efficient using leaves shaped BiVO 4 as catalyst than the bulk shaped one in photocatalytic ozonation and the synergy index is ranged from 2.8 to 3.3, indicating a superior positive synergistic effect between photocatalysis and ozonation. The higher activity of the leaves shaped BiVO 4 was probably attributed to the distinctive biomimetic morphology and preferable band structure with more negative CB potential. Mechanism studies suggested that the main reactive species were h+ and OH for the degradation of persistent oxalic acid in photocatalytic ozonation. In addition, the effect of ozone concentration and inorganic ions and reusability of the material were also intensively investigated. Graphical abstract Image 1 Highlights • Hierarchical biomimetic BiVO 4 with leaves morphology is synthesized. • L-BiVO 4 exhibits high synergy in photocatalytic ozonation process. • The reactive oxidizing species in photocatalytic ozonation is h+ and OH. • The high CB position plays an important role. [ABSTRACT FROM AUTHOR]

• Global softness of the NHCs was employed to correlate with the ozonation efficiency. • Higher global softness of NHCs resulted in a greater degradation efficiency. • Fewer N atoms in heterocyclic ring generated more OH from ozone dissociation. • Reactive sites for both O 3 and radical attack were located by FO theory. • Combined DFT and TOF-MS results were used to identify the hydroxylation products. Nitrogen-containing heterocyclic contaminants (NHCs) have aroused intense environmental issues in waterbody because of their high toxicity and strong recalcitrance against natural degradation. In this study, ozonation degradation on four typical NHCs - benzotriazole (BTA), benzimidazole (BMZ), indazole (IDZ), and indole (IDO) was carried out to investigate the effects of N atoms on degradation efficiency. Global softness of the NHCs was calculated by density functional theory (DFT) and correlated with ozonation efficiency. It was discovered that higher global softness of the NHCs resulted in the greater degradation efficiency. Mineralization results together with the quenching tests results suggested that NHCs with ortho-positioned N atoms in heterocyclic ring are easier to be mineralized, while the presence of para-positioned N atoms increased the recalcitrance for destruction. Apart from hydroxyl radicals, superoxide radicals and singlet oxygens were also identified by electron paramagnetic resonance (EPR) spectra. Condensed Fukui index was employed to probe the potential active sites for both direct ozone oxidation and radical-based attack. Single point energies were further calculated among these active sites to seek the initial-stage hydroxylation intermediates. Combined the calculation results with the identified intermediates from time-of-flight mass spectroscopy (TOF-MS), degradation routes of the NHCs were proposed. This study discovered structure-dependent behavior of NHCs on ozonation efficiency and envisaged a more accurate strategy for establishing the degradation pathway. [ABSTRACT FROM AUTHOR]