Unveiling pathways of oxytetracycline degradation induced by cold atmospheric plasma

Antibiotic pollution has received increasing global and scientific attention in recent years due to its serious impact on ecosystems and human health. As a new advanced oxidation method, Cold Atmospheric Plasmas (CAPs) have been successfully applied to degrade oxytetracycline (OTC) with a large removal rate, high energy efficiency, and environment-friendly requirements; however, the reaction pathways are still unclear. In this study, a reactive Molecular Dynamics (MD) simulation is performed to investigate the mechanisms of OTC degradation induced by Reactive Oxygen Species (ROS) in CAPs. The simulations showed the breaking of chemical bonds upon the impact of ROS, such as C–C, C–N, and C–O. In particular, the removal of important functional groups, including the acylamino at the C2 site, the dimethylamine at the C4 site, and the tertiary alcohol at the C12a site, is observed, and the destruction of these key structures indicates the degradation of OTC by reducing the antibacterial ability. The final products revealed by the computational data agree well with the experimental measurements. The dose effects on OTC degradation are also examined by adjusting the numbers of ROS in the simulation box. This study can further enhance the understanding of OTC degradation induced by CAP according to the reactive MD simulation results, unveiling the key pathways of OTC degradation.