Contaminants modulated the dominant ROS and reaction pathways: Rapid degradation for free DNA bases and antibiotic resistance genes in fenton-like process

The removal of DNA bases, main components of antibiotic resistance genes (ARGs) can provide a microscopic understanding of the degradation mechanism of ARGs. However, most previous studies concentrated on the effects of different materials/PMS on DNA bases, while neglecting the influence of the DNA bases characteristic. Thus, four DNA bases (adenine (A), guanine (G), cytosine (C) and guanine (G)) were selected and degraded by Co-Mn N-doped composites (CoMn@NC)/PMS system in this study. There were differences in reaction time for completely degrading four bases (5 min of A and G, 10 min of C, and 20 min of G). The reaction rate of different bases showed an obvious negative correlation (R² = 0.809) with their electrophilicity index. Non-radical pathways (¹O₂ and electron transfer) assumed a greater role in the degradation of bases with lower electrophilicity indices (A and G). While the base T with a higher electrophilicity index reflected a lower degradation efficiency. The reactive sites and degradation pathways of different bases revealed that better removal performance of bases A and G was also attributed to the synergistic oxidation of free and non-free radical ways. In addition, CoMn@NC/PMS could also completely inactivate antibiotic resistant bacteria (ARB) and efficiently degrade ARGs released from ARB within 30 min. Overall, this work proposed the electrophilicity index and reactive sites of DNA bases could influence PMS activation, providing an alternative strategy for selective and efficient degradation of ARGs.