Carbon-defect-driven persulfate activation for highly efficient degradation of extracellular DNA contaminant: Radical oxidation and electron transfer pathways

Extracellular DNA (eDNA), as a dynamic repository for antibiotic-resistant genes (ARGs), is a rising threat to public health. This work used a ball-milling method to enhance defect structures of activated carbon, and carbon defects exhibited an excellent capacity in persulfate (PS) activation for model eDNA and real ARGs degradation. The eDNA removal by defect-rich carbon with PS was 2.3-fold higher than that by unmilled activated carbon. The quenching experiment, electrochemical analysis and thermodynamic calculation showed that carbon defects could not only enhance the generation of SO4 center dot- and center dot OH, but formed an electron transfer bridge between eDNA and PS, leading to the non-radical oxidation of eDNA. According to molecular calculations, the nitrogenous bases of DNA were the easiest sites to be oxidized by electron transfer pathway. This research offers a new way using defective carbon materials as PS activator for eDNA pollutants, and an insight into the non-radical mechanism of eDNA degradation.

Automated summary

This study used a ball-milling method to enhance the defect structures of activated carbon, which showed excellent persulfate activation capacity for the degradation of model extracellular DNA and real antibiotic-resistant genes. The removal efficiency of extracellular DNA by defect-rich carbon with persulfate was 2.3 times higher than that by unmilled activated carbon. The research demonstrated that carbon defects not only enhanced the generation of reactive species, but also facilitated electron transfer between extracellular DNA and persulfate, leading to non-radical oxidation. The findings provide a new approach for utilizing defective carbon materials as persulfate activators for extracellular DNA pollutants and offer insights into the non-radical degradation mechanism of extracellular DNA.