Turning green tide into treasure: ball-milled and N-doped Enteromorpha prolifera biochar for peroxymonosulfate activation via a synergy of reactive species

To address the ecological problem caused by the accumulation of green tide Enteromorpha prolifera and the challenge of remediating organic pollutants in water bodies, this study utilized Enteromorpha prolifera as raw materials to synthesize a novel nitrogen-doped biochar (NBPBC) catalyst through ball-milling and pyrolysis. The resulting catalyst was applied to activate peroxymonosulfate (PMS) for antibiotic tetracycline (TC) degradation. The optimized NBPBC exhibited a large specific surface area (62.0022 m 2 /g) and a high content of graphitic nitrogen. Experimental results showed that the NBPBC/PMS system achieved 100% removal efficiency towards TC within 60 min with a rate constant k  = 0.06629 min − 1 , significantly outperforming systems without ball-milling or nitrogen doping. Additionally, NBPBC maintained good a catalytic activity and stability after six cycles, with the TC degradation efficiency remaining above 80%. Mechanistic studies revealed that the catalytic mechanism was dominated by ∙O 2 − , with synergistic contributions from ∙OH, 1 O 2 and SO 4 ∙ − . This work achieves the high-value utilization of Enteromorpha prolifera waste and provides an efficient strategy for aquatic organic pollutant remediation, offering a dual-win solution to ecological and environmental challenges. Graphical abstract A novel N-doped biochar catalyst based on Enteromorpha prolifera was synthesized through a ball-milling and single-step pyrolysis method, which can effectively activate PMS to realize the rapid degradation of organic pollutants and the high-value utilization of Enteromorpha prolifera .