Synthesis, characterization and investigation of photocatalytic activity of ZnMnO3/Fe3O4 nanocomposite for degradation of dye Congo red under visible light irradiation

Authors

• Azam Zamani ¹
• Mirabdullah Seyed Sadjadi * ¹
• Alireza Mahjoub ²
• Mohammad Yousefi ³
• Nazanin Farhadyar ⁴

1. Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran
2. Department of Chemistry, Tarbiat Modares University, Tehran, Iran
3. Department of Chemistry, Yadegar-E-Imam Khomeini(RAH) Shahre Rey Branch, Islamic Azad University, Tehran, Iran
4. Department of Chemistry, Varamin Pishva Branch, Islamic Azad University, Varamin, Iran

Abstract

ZnMnO₃/Fe₃O₄ magnetic nanocomposites were fabricated via facile co-precipitation route and were calcined at 400 °C for 3 h. Synthesis of ZnMnO₃/Fe₃O₄ magnetic nanocomposites were optimized by different weight percentages. Then, the as-synthesized sample was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), photoluminescence(PL), vibrating Sample Magnetometer (VSM), EDAX (Energy dispersive X-ray analysis), diffuse reflectance UV–Vis spectroscopy (DRS),ultraviolet–visible (UV–Vis) spectrometry, Bruner-Emmett-Teller (BET), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Based on the results, elemental analyses of the samples were similar to those expected from the initial concentrations of the solutions used during synthesis. The x-ray diffraction pattern revealed that ZnMnO₃/Fe₃O₄ has a cubic structure and average particle size of the catalyst was found 27.43 nm. In addition, Fourier transform infrared spectra could confirm the presence of hydroxyl group and Fe–O bond vibration in the catalyst. Further, the superparamagnetic behavior of the synthesized nanocomposite at room temperature was confirmed by VSM studies. Furthermore, the photocatalytic performance of ZnMnO₃/Fe₃O₄ samples were evaluated based on the removal of Congo red (CR) in aqueous solution in 60 min of under visible light irradiation. The experiment demonstrated that 0.10 g of ZnMnO₃/Fe₃O₄ nanocomposites can degrade (98.17%) 50 mg l⁻¹ of Congo red (CR) solution. The mechanistic study using scavengers propose that the superoxide (O2^·−) is the most reactive species involved in the photodegradation of organic dyes. The photocatalytic degradation of Congo red conformed the pseudo-first-order kinetic model and the rate constant achieved for 0.10 g l⁻¹ of ZnMnO₃/Fe₃O₄ was (k = 0.0384 min⁻¹). Finally, the effect of reaction time, pH, and loading of ZnMnO₃/Fe₃O₄ on degrading Congo red was studied. The synthesized ZnMnO₃/Fe₃O₄ nanocomposite can be potentially applied as a magnetically separable photocatalyst to deal with water pollution problems.

Keywords

• Congo Red
• ZnMnO3/Fe3O4
• Degradation
• Nanocomposite
• Photocatalytic Activity
• Co-precipitation method