Photocatalytic degradation of methylene blue in aqueous solution by magnetic ZnMn2O4@copper porphyrin nanocomposite

Magnetic photocatalyst [magnetic@silica@zinc manganate, Fe3O4@SiO2@ZnMn2O4] (MZMO) and [magnetic@silica@zinc manganate@copper tetra hydroxyl phenyl porphyrin, Fe3O4@SiO2@ZnMn2O4@CuIITHPP] (MZMOCuP) nanocomposites were prepared using green synthesis method and characterized by means of Fourier transform-infrared, scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometer (VSM) and ultra-violent-diffuse reflectance spectroscopy techniques. The magnetic properties of the synthesized samples were measured by a VSM with maximum saturation magnetization values of 10 and 8 emu g−1 for MZMO and MZMOCuP nanocomposites, respectively. UV-diffuse reflectance spectroscopy data of MZMOCuP indicate the red shift of the absorption edge and reduction of the band gap from 1.4 to 1.1 eV in comparison with MZMO. The nanocomposite of MZMOCuP showed excellent photocatalytic activity for photodegradation of methylene blue (MB) in aqueous solution under visible-LED light irradiation. The degradation of MB was monitored by UV–Vis spectrophotometer. Maximum degradation of 98% for MB was obtained in the presence of MZMOCuP nanocomposite as the photocatalyst and under 180 min irradiation of 3 W blue LED light. The recovery of the photocatalyst was easily performed by using an external magnetic field.