Activation of peroxydisulfate by black fungus-derived N-doped biochar for tetracycline degradation via non-radical dominated oxidation pathway

N-doped biochar (N-BC) was prepared from black fungus by coupling a hydrothermal method with thermal pyrolysis, and the physicochemical properties of N-BC were characterized in detail by various techniques. As-synthesized N-BC exhibited a better catalytic performance to activate peroxydisulfate (PDS) for tetracycline (TC) degradation compared with as-obtained N-doped hydrochar (N-HC), N-doped calcined carbon (NCC) and most of the reported carbon catalysts. After reaction of 60 min, 89.8% of TC (20 mg/L) was degraded by N-BC/PDS oxidation system, and TC degradation obeyed the pseudo-second-order kinetic with a reaction rate constant at 0.843 L⋅mg−1⋅min−1. The effect of some important parameters (N-BC dosage, PDS dose, initial TC concentration, solution pH, reaction temperature and inorganic anions) on TC degradation was also investigated and analyzed. The radical trapping experiments, EPR test, and electrochemical analysis confirmed that TC degradation in N-BC/PDS system was achieved via the radical (SO4•−, ‧OH) and non-radical (1O2, electron transfer) pathways, and the later played the dominant role. Finally, the performance of N-BC/PDS oxidation system for the removal of TC from the different real water matrices was studied. This study provided a new material for the preparation of highly active PDS catalyst for the treatment of antibiotic wastewater.