Sensitization of magnetic TiO₂ with copper(II) tetrahydroxylphenyl porphyrin for photodegradation of methylene blue by visible LED light

Magnetic photocatalyst (magnetite@silica@titania@copper(II) 5,10,15,20-tetrakis(4-(hydroxyl)phenyl) porphyrin, Fe₃O₄@SiO₂@TiO₂@Cu^IITHPP) (MSTCuP) has been synthesized, characterized, and utilized to degrade the methylene blue (MB) under a visible LED light irradiation. The structural characteristics of the MSTCuP were determined using FT-IR, SEM, EDX, XRD, BET and VSM techniques. The magnetic properties of the synthesized samples were measured by a vibrant sample magnetometer (VSM) with maximum saturation magnetization values of 10 and 8 emu g⁻¹ for Fe₃O₄@SiO₂@TiO₂ (MST) and Fe₃O₄@SiO₂@TiO₂@Cu^IITHPP (MSTCuP) nanoparticles respectively. UV-DRS data show the red-shift of the absorption edge and decrease of the band gap to 1.8 eV. The degradation of MB was monitored by UV–Vis spectrometry. Maximum degradation of %98 for MB dye was attained by the use of MSTCuP nanocomposites as the catalyst and under 180 min irradiation of blue LED light. After three 180 min photocatalytic runs for MB degradation, the catalyst still showed high activity. The recovery of the catalyst was easily performed by applying the external magnetic field. The efficiency of green, red and yellow Vis-LED light sources for the photocatalytic degradation of MB was also investigated. The degradation of MB using MSTCuP nanocomposite was found to follow the pseudo-first-order kinetic.