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Ornidazole (ONZ) is an emerging pollutant posing a huge threat to the environment and humans. In this paper, the degradation mechanism of ONZ on anatase TiO2(101) and (001) surfaces in vacuum and neutral aqueous solution was elucidated at the DFT level. We found that ONZ was activated and oxidized after being adsorbed on the surface of TiO2; the C–N bond became longer, making the ring-opening degradation more likely to occur. This study found that the degradation of ONZ is more probable on the surface of TiO2(001) than on TiO2(101). When the surroundings of the reaction was changed from a vacuum to aqueous solution, the activation energy of ONZ degradation reaction on TiO2 surfaces was decreased, which indicated that the solvent condition was more favorable for ONZ degradation. [ABSTRACT FROM AUTHOR]

The adsorption characteristics of metronidazole on anatase TiO2(101) and (001) surfaces were studied by density functional theory (DFT). The adsorption structure of metronidazole on anatase TiO2(101) and (001) surfaces has been optimized under vacuum, water, acidic, and alkaline conditions, respectively. The optimum adsorption site, adsorption energy, and electronic structure of the stable adsorption model were calculated. The adsorption characteristics of metronidazole on two different surfaces of TiO2 were studied under acidic and alkaline conditions. Our calculated results found that the adsorption energy range is −0.95 ~ −3.11 eV on the TiO2 (101) surface, and the adsorption energy range is −0.84 ~ −3.29 eV on the TiO2 (001) surface. The adsorption wavelengths of electron transition between valence band and conduction band of metronidazole on the anatase TiO2(101) surface is in the range of visible wavelength, indicating that the TiO2(101) surface can effectively utilize visible light. However, the photocatalytic effect of the TiO2(001) surface is greatly affected by the environment. The results reveal the adsorption characteristics and the environmental influence for metronidazole on photocatalytic anatase TiO2 surfaces. Graphical abstract The adsorption characteristics of metronidazole on anatase TiO2(101) and (001) crystal surfaces were studied by density functional theory (DFT). [ABSTRACT FROM AUTHOR]

The adsorption characteristics and degradation mechanism of tinidazole on TiO 2 (101) and (001) surfaces under vacuum and aqueous solution conditions were studied by density functional theory (DFT). The results show that tinidazole can adsorb on the surfaces of TiO 2 (101) and (001) under different conditions. The hydrogen bond generated during the adsorption process can enhance the stability of the adsorption configuration, which makes the bond length of C-N of tinidazole longer and finally facilitates the ring-opening degradation reaction. As for the mechanism of the ring-opening degradation reaction, it was found that ring-opening can be carried out along reaction route II on both crystal surfaces, and the reaction activation energy is lower on (101) surface. Under the conditions of aqueous solution, the decrease of the activation energy of the ring-opening degradation reaction indicates that the solvent conditions can promote the degradation reaction., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)