Discoloration of methylene blue at neutral pH by heterogeneous photo-Fenton-like reactions using crystalline and amorphous iron oxides
Different iron oxides were evaluated for the discoloration of methylene blue (MB) at neutral pH by heterogeneous photo-Fenton-like reactions with a UV-LED lamp. Fe3O4, α-Fe2O3, and a-FeOOH catalysts were synthesized and characterized by X-ray diffraction, scanning electron microscopy (SEM), Raman sp...
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| Autores principales: | , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
De Gruyter
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/1e20f660523b43ada06371e7873e3ef4 |
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| Sumario: | Different iron oxides were evaluated for the discoloration of methylene blue (MB) at neutral pH by heterogeneous photo-Fenton-like reactions with a UV-LED lamp. Fe3O4, α-Fe2O3, and a-FeOOH catalysts were synthesized and characterized by X-ray diffraction, scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy, and adsorption isotherms of N2. The results show high crystallinity and relatively low surface areas for Fe3O4 and α-Fe2O3, and amorphous structure with high surface area for the case of a-FeOOH. The discoloration of MB by iron oxides as catalysts was studied using UV-Vis spectroscopy. Despite the relative high adsorption of MB for magnetite (12%) compared to the other oxides, it shows a slow discoloration kinetics. Besides, amorphous oxide (named a-FeOOH) shows a higher discoloration kinetics with negligible adsorption capacity. The pseudo first-order kinetic constant values for Fe3O4, α-Fe2O3, and a-FeOOH are 5.31 × 10−3, 6.89 × 10−3, and 13.01 × 10−3 min−1; and the discoloration efficiencies at 120 min were 56, 60, and 82%, respectively. It was testified that low crystallinity iron oxide can be used in the efficient discoloration of MB by photo-Fenton process with a hand UV-A lamp. |
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