Synthesis and characterization of a novel manganese ferrite–metal organic framework MIL-101(Cr) nanocomposite as an efficient and magnetically recyclable sonocatalyst

Abstract

This research reports that a novel magnetic sonocatalyst nanocomposite, MnFe₂O₄/MIL-101(Cr), has been effectively created utilizing a simple hydrothermal strategy. The as-prepared catalyst was thoroughly well-characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, vibrating sample magnetometry (VSM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and UV-Vis diffuse reflectance spectroscopy (DRS). This newly synthesized and magnetically recyclable sonocatalyst nanocomposite was applied under ultrasonic irradiation for the degradation of organic pollutants. The outcomes showed complete degradation of rhodamine B (RhB) (25 mg L⁻¹) in the presence of MnFe₂O₄/MIL-101(Cr) and H₂O₂ (60 mmol L⁻¹) as a green oxidant within 180 min. On the other hand, sonodegradation reactions of dye contaminants were investigated using a first-order kinetic model. The rate constant (k) data were obtained as 0.0161 min⁻¹, for the degradation of RhB in the MnFe₂O₄/MIL-101(Cr)/H₂O₂/US system. Compared with raw MnFe₂O₄ and raw MIL-101(Cr), the heterogeneous MnFe₂O₄/MIL-101(Cr) nanocomposite exhibited significantly enhanced sonocatalytic efficiency mainly due to the high efficiency in the separation of the electron–hole pairs induced by the remarkable synergistic effects of the MIL-101(Cr) and MnFe₂O₄ semiconductors. Besides, trapping experiments confirmed that ˙OH radicals were the main reactive species in the present sonocatalytic system for dye degradation. The effects of the main operating parameters such as H₂O₂ concentration, catalyst dosage, and dye initial concentration have also been investigated. After all, the nanocomposite could be effortlessly separated and recycled from the de-contaminated solution using a magnet without a considerable decrease in its sonocatalytic activity due to excellent chemical stability.