Tetracycline degradation by persulfate activated with nitrogen magnetic graphene oxide confined Fe/Co dual single-atom catalyst: Performance and degradation mechanism

Tetracycline (TCN) is a typical antibiotic with ecological toxicity, which is easy to cause bacterial drug resistance. Single-atom catalysts have a broad application prospect in the remediation of antibiotic polluted water by activated persulfate (PDS), but its catalytic properties are limited because of its high surface energy and easy aggregation. Therefore, in our manuscript, a novel nitrogen doped magnetic graphene oxide confined Fe-Co dual single-atom catalyst (Fe/Co(1:1)(S)-NMGO) was prepared by one-step molten salt assisted high temperature pyrolysis. XPS and AC-HAADF-STEM analysis indicated single-atom Fe and Co existed. Fe and Co atoms were bound to the material mainly through coordination with pyridinic N and pyrrolic N. While single-atom Fe and Co were simultaneously introduced into the modified materials, the removal rate of TCN reached 93.1%, implying the significant synergistic effect of single-atom Fe and Co on TCN removal. Molten salt assisted high-temperature pyrolysis significantly improved the TCN degradation rate. In addition, this research showed that the existence of magnetite nanoparticles was beneficial to improve the separation performance of the single-atom catalysts as well as the catalytic performance. At the same time, the effects of some key parameters (Fe/Co molar ratio, catalyst dosage, PDS dosage, initial pH, coexisting anions and humic acids) on TCN degradation in Fe/Co(1:1)(S)-NMGO/PDS system were also investigated. The catalytic potential in actual water and regeneration performance of the material were also evaluated. The possible activation mechanism and degradation pathway of TCN were proposed. These findings will provide important reference for the future design and application of single-atom-involved catalysts.