Efficiency and mechanisms of tetracycline removal from water by enhanced peroxymonosulfate activation via carboxylated Fe2+

• • Achieved 88.80% tetracycline degradation within 60 min under optimized conditions (TC 5 mg·L−1, Fe2+ 0.02 mmol·L−1, CA 0.001 mmol·L−1, PMS 2 mmol·L−1), demonstrating high efficiency for antibiotic removal without external energy input. • • Identified singlet oxygen (1O2) as the dominant reactive species with a 50.5% contribution, followed by sulfate radicals (SO4•−) at 35.7%, enabling selective oxidation and robustness in complex matrices. • • Carboxylation with citric acid (CA) enhanced Fe2+ stability and catalytic activity, reducing iron sludge formation and overcoming limitations of traditional Fenton processes (e.g., H2O2 instability, heterogeneous catalyst complexity). • • Phytotoxicity tests showed no significant toxicity to wheat seedlings (P > 0.05), confirming the ecological safety of treated water and absence of secondary pollution, supporting practical application.