Yuxue Shan,Yanyan Liu,Li Feng,Shuao Yang,Xiaohong Tan,Zerong Liu
Tetracycline is an organic compound that poses a significant threat to both the ecological environment and human health during its long-term production and use. Advanced oxidation processes based on sulfate radicals (SR-AOP) have been recognized as effective techniques for treating antibiotic contamination. However, The urgent demand for a green, efficient, and recyclable catalyst to effectively facilitate persulfate treatment of tetracycline pollution is evident. Magnetic Fe 3 O 4 -C@MoS 2 composite were synthesized using hydrothermal and pyrolysis methods. Degradation experiments, free radical quenching experiments, EPR analysis were carried out to investigate the degradation performance and mechanisms of Fe 3 O 4 -C@MoS 2 composite. Results showed that the degradation efficiency of 100 mL of 20 mg/L tetracycline solution reached up to 97% within 40 mins with the dosage of 20 mg Fe 3 O 4 -C@MoS 2 and 30.7 mg peroxmonosulfate. Furthermore, this degradation system exhibited excellent efficiency even over a wide pH range of 3–9. The transformation of Mo (IV) and S 2- /S n 2- species valence states facilitated the conversion between Fe(III)/Fe(II). Both free radical ( S O 4 ⋅ − , ⋅ O H and O 2 ⋅ − ) as well as non-free radical species ( O 2 1 ) were found to accelerate the catalytic reaction during the tetracycline degradation. The possible pathways of tetracycline degradation were proposed, and the toxicity of the intermediate products were proved to be lower than that of tetracycline. Finally, magnetic Fe 3 O 4 -C@MoS 2 composites possessed good reusability and stability after 4 cycles of degradation.
Nankun Chen,Yiyao Xiao,Chao Wang,Jiahao He,Ningning Song
Ternary hierarchical Fe3O4@C@MoS2 composites and binary hierarchical Fe3O4@C composites were successfully fabricated by a modified mixed solvothermal method, a self-oxidation polymerization method, and a hydrothermal process. Their magnetic properties and microwave absorption performance were investigated. Dual resonance behavior was observed in the Fe3O4@C@MoS2 composites. One of the resonances was attributed to natural resonance with a resonance frequency of 2.58 GHz, which was much higher than that for Fe3O4 bulk (1.5 GHz). The other originated from the superparamagnetic/ferromagnetic relaxation with a resonance frequency of 12.45 GHz. The minimum reflection loss (RLmin) reached −64.30 dB with a matched thickness of 2.24 mm at 11.64 GHz, and the maximum effective absorption bandwidth (EABmax) covered 6.39 GHz with a matched thickness of 1.89 mm. In addition, the maximum Radar cross section (RCS) reduction value reached 31.90 dB m2 at a scattering angle of 0°. Electron holography analysis confirmed a dense magnetic absorption network in the Fe3O4@C@MoS2 composites. The boost in microwave absorption performance was caused by the synergistic effects of magnetic and dielectric properties owing to the ternary hierarchical structure, shape magnetic anisotropy, and incorporation of 1T/2H MoS2. Besides, the binary hierarchical Fe3O4@C composites also exhibited good absorbing performance caused by natural resonance, with an RLmin of −52.90 dB at 5.80 mm, an EABmax of 5.98 GHz at 3.38 mm, and a relatively high RCS reduction value of 13.04 dB m2 at θ = 20°. This work paves the way for designing multicomponent hierarchical absorbers with broadband and intensive microwave absorption.
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