Azam Zamani - Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Mirabdullah Seyed Sadjadi - Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Ali Reza Mahjoub - Department of Chemistry, Tarbiat Modares University, Tehran, Iran.
Mohammad Yousefi - Department of Chemistry, Yadegar-e-Imam khomeini (RAH) Shahre Rey Branch, Islamic Azad University, Tehran, Iran.
Nazanin Farhadyar - Department of Chemistry, Varamin Pishva Branch, Islamic Azad University, Varamin, Iran.

In the present investigation, ZnFe۲O۴@MnO and MnFe۲O۴@ZnO magnetic nanocomposites were fabricated via a facile hydrothermal method and were calcined at ۳۰۰ °C for ۳ h. Synthesis of ZnFe۲O۴@MnO and MnFe۲O۴@ZnO magnetic nanocomposites optimized by the different weight percentages. The synthesized photocatalyst was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Vibrating Sample Magnetometer (VSM), EDAX (Energy dispersive X-ray Analysis), diffuse reflectance UV-vis spectroscopy (DRS)  and field emission scanning electron microscopy (FESEM). The ZnFe۲O۴@MnO nanoparticles were found to have ۲۰-۵۰ nm. Magnetic studies revealed that the ZnFe۲O۴@MnO and MnFe۲O۴@ZnO nanocomposites can be easily separated from the solution by an external magnetic field. The photocatalytic degradation of Congo red dye (CR) was investigated based on the removal of Congo red (CR) in aqueous solution in ۳۵ min of visible light irradiation. Compared with MnFe۲O۴@ZnO nanocomposite, the ZnFe۲O۴@MnO nanocomposite showed high photocatalytic performance on the photodegradation of Congo red. Effect of reaction time, pH, and loading of ZnO on degradation of CR was studied,The results demonstrated that the degradation efficiency of ZnFe۲O۴@MnO nanocomposite (۹۸.۵%) was better than that of MnFe۲O۴@ZnO nanocomposite (۹۰.۳۲%), which is due to the presence of narrow band gap energy of ZnFe۲O۴@MnO.Kinetics studies have displayed  that the degradation of CR by the prepared of photocatalysts follows the pseudo-first-order kinetics and the rate constant achieved for ZnFe۲O۴@MnO (k=۰.۰۳۷۱ min−۱) was much greater than of MnFe۲O۴@ZnO (k=۰.۰۳۲۱ min−۱). The synthesized ZnFe۲O۴@MnO nanocomposite can be potentially applied as a magnetically separable photocatalyst to deal with water pollution problems.

Congo Red, Hydrothermal Method, Magnetical Nanocomposites, Photocatalytic Activity, Visible Light