Construction and extension of carbon network conjugated systems under high temperature regeneration for cycling degradation of Naproxen by activating peroxymonosulfate: mechanisms of active sites self-cycling and reactive oxygen species regulation

The development of metal-free catalysts with excellent reusability and the research of effects for carbon network structures in activation process are great challenges in non-metallic catalysis today. In this study, a regenerated metal-free biochar (Re-TBC-800) was prepared by pyrolyzing multi-use black tea biochar (TBC-800) to activate peroxymonosulfate (PMS) for cycling degradation of naproxen (NPX) up to 48 times (only 6 times before regeneration). It was demonstrated by Raman and DFT calculations that the rearrangement of carbon networks during thermal regeneration resulted in the formation of a higher conjugated structure. After regeneration, C−O changed from electron acceptor to electron donor to achieve self-cycling between C=O and C−O. The reaction pathways changed from a non-radical (¹O₂ and electron transfer) effect to a synergistic (•OH, SO₄^•−, ¹O₂ and electron transfer) effect. Re-TBC-800 provided new insights into the structural design of functional catalysts.