Highly efficient activation of peroxymonosulfate for rapid sulfadiazine degradation by Fe₃O₄ @Co₃S₄

Low Fe²⁺/Fe³⁺ cycling efficiency is the key factor limiting the efficiency of magnetic nanoparticles in advanced oxidation process. In this study, Co₃O₄ nanosheets were modified on the surface of Fe₃O₄ particles to design a series of efficient and stable Fe₃O₄@Co₃O₄-X catalysts. Within the wide pH range of 3.0∼10.0, Fe₃O₄@Co₃S₄-3/PMS system can degrade more than 95% of sulfadiazine (SDZ) within 5 min, and its catalytic activity was significantly higher than Fe₃O₄/PMS and Co₃S₄/PMS. Except SDZ, Fe₃O₄@Co₃S₄-3/PMS system also efficiently degraded sulfonamides, chloroxylenol, bisphenol S, bisphenol A, 2,4-dichlorophenol within 5 min. Quenching experiments and electron paramagnetic resonance (EPR) analysis confirmed that the main active species in the above system were SO·- 4and ¹O₂. Active Co(II) reduced Fe(III) on the surface of Fe₃O₄ to Fe(II), and the electron transfer between them promoted the Fe²⁺/Fe³⁺ cycle. Sulfur accelerated the cycle of Co³⁺/Co²⁺ and Fe²⁺/Fe³⁺, the synergistic effect between the two improved the catalytic activity and the decomposition efficiency of PMS. The unique core-shell structure of the composite effectively improves the catalytic activity and reduced the metal ions leaching. This study provides an effective strategy and theoretical support for the improvement and efficient utilization of magnetic nanoparticles, and reveals the degradation path of SDZ in the iron- and cobalt-based catalysts system. Copyright © 2022 Elsevier B.V. All rights reserved.