Density functional theory calculations on the adsorption and degradation characteristics of ronidazole on the TiO2 surface

In this paper, density functional theory (DFT) is used to study the adsorption characteristics and degradation mechanisms of ronidazole (RNZ) on different surfaces of TiO2. The stable adsorption configurations of RNZ on different surfaces of TiO2 are obtained. The structural changes of the stable adsorption structures are carefully analyzed. It is found that the adsorption of RNZ on surfaces of TiO2 is chemical adsorption, and there is hydrogen bond interaction between RNZ and different surfaces of TiO2 during the adsorption process. This study reveals that all the adsorption processes of RNZ on different surfaces of TiO2 activate the C-N bond of the imidazole ring, which is beneficial to the photocatalytic reaction. We also studied the degradation reaction mechanisms of RNZ on different surfaces of hydroxylated TiO2, and studied two different degradation reaction channels of RNZ on different surfaces of TiO2. From the results of the energy barrier study of the degradation reaction, RNZ proceeds along the reaction path (RR1 -> RTS1 -> RM1 -> RTS2 -> RP1), and the main ring-opening product of the degradation is the formation of the C-N bond breaking of the imidazole ring of the RNZ, which is consistent with the results reported in previous experiment.