Enhanced peroxymonosulfate activation for antibiotic removal using Ni₁Mn₁Fe₁-LDO/g-C₃N₄: Metallic electronic synergy...

By combining unique advantages of layered double oxides (LDOs) and graphitic carbon nitride (g-C₃N₄), Ni₁Mn₁Fe₁-LDO/g-C₃N₄ composite was fabricated for efficient degradation of ciprofloxacin (CIP) through peroxymonosulfate (PMS) activation. Under the optimal condition, 80% of CIP was rapidly removed within 5 min, and the time required for 100% degradation was shortened by 33.3% compared with Ni₁Mn₁Fe₁-LDO/PMS system. The incorporation of g-C₃N₄ effectively enhanced structural stability of Ni₁Mn₁Fe₁-LDO/g-C₃N₄ composite, enabling it to retain 91.2% of catalytic activity after five consecutive runs, and the catalyst had a low level of metal leaching. The operation conditions of Ni₁Mn₁Fe₁-LDO/g-C₃N₄ with PMS system were optimized using the response surface analysis and experiments. Multiple active species (SO₄^•-, •OH, O₂^•-, and ¹O₂, etc.) collectively contributed to CIP removal, and surface-bound SO₄^•- and ¹O₂ served as the primary ones. The combination of Ni₁Mn₁Fe₁-LDO and g-C₃N₄ facilitated the generation of oxygen vacancies (O_V) and persistent free radicals (PFRs), thereby improving electron transfer efficiency, accelerating reaction kinetic, and ultimately enhancing catalytic performance. The removal pathways and mechanism of CIP were elucidated in the as-constructed system. This work presented a novel strategy for constructing an efficient and cyclically stable Ni₁Mn₁Fe₁-LDO/g-C₃N₄ catalyst for PMS activation, offering valuable guidance for the improvement and practical application of SR-AOPs technology in wastewater treatment.