Preparation and application of α-Fe₂O₃@MIL-101(Cr)@TiO₂ based on metal–organic framework for photocatalytic degradation of paraquat

Abstract

In this study, a new magnetic-Fe 2 O 3 @MIL-101(Cr)@TiO 2 photocatalyst was successfully synthesized. The material synthesized had been fully characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, transmission electron microscopy, and Brunauer-Emmett-Teller isotherm methods. The X-ray diffraction analysis corroborates that nanoparticles are polycrystalline with rhombohedral and tetragonal crystal structures for Fe 2 O 3 and TiO 2 , respectively. In addition, the photocatalytic degradation of the herbicide paraquat in the presence of-Fe 2 O 3 @MIL-101(Cr)@TiO 2 under ultraviolet (UV) irradiation was studied. The effect of experimental parameters such as the initial concentration of catalyst, the pH, and the initial paraquat was investigated. The optimal conditions were achieved for concentration of catalyst 0.2 g L À1 , pH 7, and concentration of paraquat 20 mg L À1. The photocatalytic degradation efficiency was 88.39% after 15 min with-Fe 2 O 3 @MIL-101(Cr)@TiO 2 under UV irradiation. The pseudo-second-order kinetic model for photocatalytic degradation of paraquat was obtained. The catalysts could be recovered and reused without any loss of efficiency for five times in the consequent reactions. To the best of our knowledge, this is the first report on the photocatalytic degradation of paraquat using new-Fe 2 O 3 @MIL-101(Cr)@TiO 2 photocatalyst under UV irradiation condition.

State of the Art and Prospects in Metal–Organic Framework (MOF)-Based and MOF-Derived Nanocatalysis

“…Nanomaterials including TiO 2 semiconductor as multifunction photocatalysts have been reviewed by Zou’s group who has also appropriately emphasized the specificity and interest of the construction of robust Ti­(IV)-based MOFs for these applications . TiO 2 has recently been associated with MIL-88B, MIL-101, and MIL-125. ,− Other associated semiconductors mostly include metal oxides such as α-Fe 2 O 3 with UiO-66, Fe 3 O 4 with MIL-100­(Fe), ZnO with ZIF-8, ZrO 2 with HKUST-1, Ag 2 WO 4 with UiO-66, and rare cases of metal phosphates such as Ag 3 PO 4 with MIL-53 (Fe) and UMOFN, CdS with MIL-53­(Fe) . Magnetic catalysts among the semiconductors, i.e., α-Fe 2 O 3 are especially useful for recycling. , Coupled to NH 2 -MIL-125, QDs served as both electron acceptors promoting photoinduced charge separation and spectrum converter to convert NIR light into visible light .…”

Tris(2-benzimidazolyl)amine (NTB)-Modified Metal-Organic Framework: Preparation, Characterization, and Mercury Ion Removal Studies

“…To obtain clear data, adsorption was conducted using a solution containing 50 ppm Hg 2+ ions to obtain MIL-101-NTB (after adsorption). The FTIR spectra of the pristine MOF contains a band at 1625 cm −1 corresponding to bending vibrations due to the adsorbed water on the surface of MIL-101 [37]. The band at 1392 cm −1 is attributed to symmetric (O-C-O) dicarboxylate vibrations, confirming the presence of a BDC linker inside the MIL-101 framework structure [38].…”

Synthesis, characterization, and application of α‐Fe2O3@TiO2@SO3H photo‐Fenton catalyst for photocatalytic degradation of biologically pre‐treated wood industry wastewater

“…XRD measurement differentiated α-Fe 2 O 3 phases from γ-Fe 2 O 3 (Figure 3). In the second step, the sol-gel technology was used to synthesize the magnetic α-Fe 2 O 3 @TiO 2 photocatalyst (Khodkar et al, 2018). A total of 0.5 g of α-Fe 2 O 3 nanoparticle was dispersed in water-ethanol solution (volume ratio: 1:20).…”