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, Co3S4 nanosheets were modified on the surface of Fe3O4 particles to design a series of efficient and stable Fe3O4@Co3S4-X catalysts. Within the wide pH range of 3.0 similar to 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/ 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 O-1(2). 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.