Novel magnetically recoverable MnFe2O4/TiO2 nanocomposites synthesized using green route for photocatalytic degradation of methylene blue
Deska Lismawenning Puspitarum, Nurul Imani Istiqomah, Dyah Ayu Larasati, Nining Sumawati Asri, Julia Angel, Ahmad Kusumaatmaja, Edi Suharyadi
Abstract
The photocatalytic degradation of hazardous organic dyes was investigated using green-produced MnFe 2 O 4 /TiO 2 nanocomposites, which demonstrated magnetic reusability and separability, making them efficient photocatalysts for rapid UV degradation. The MnFe 2 O 4 /TiO 2 diffraction peaks indicated a single-phase cubic spinel structure, with crystallite sizes spanning from 5.3 to 7.1 nm. The TiO 2 anatase phase showed typical peaks at 25.8° and 48.2°, corresponding to the (110) and (200) diffraction planes, respectively. The transmission electron microscopy image of MnFe 2 O 4 /TiO 2 revealed inter-grain aggregation between the particles. The particle size of MnFe 2 O 4 /TiO 2 exhibited a slight increase from 30 to 40 nm. MnFe 2 O 4 appeared as black spheres, whereas TiO 2 appeared as grey circles. X-ray spectroscopy confirmed the matching of chemical elements. The bandgap of the nanocomposites decreased from 2.9 to 3.2 eV after the surface treatment with TiO 2 , indicating an electronic transition between the two components. Furthermore, the addition of TiO 2 affected the saturation magnetization, which ranged from 7.6 to 11.2 emu/g. The nanocomposites clearly displayed superparamagnetic-like behavior. A photocatalytic investigation showed that MnFe 2 O 4 /TiO 2 nanoparticles exhibited higher photocatalytic activity than MnFe 2 O 4 nanoparticles. Methylene blue dye was degraded by 98 % using the MnFe 2 O 4 /TiO 2 nanocomposites after 2 h of UV exposure. This photodegradation was further investigated using a Langmuir–Hinshelwood kinetic model, and it was discovered that the rate constant ( K app ) increased with the TiO 2 concentration. The nanocomposites maintained over 90 % photocatalytic efficiency without any significant degradation after three reuse cycles. Therefore, green-synthesized MnFe 2 O 4 /TiO 2 nanocomposite photocatalysts for dye degradation are highly promising for the removal of harmful organic dyes from the environment. • Green-synthesized MnFe 2 O 4 /TiO 2 nanocomposites have high photocatalytic performance. • The MnFe 2 O 4 /TiO 2 were easily separated from the aqueous solution using magnet. • MB degradation of about 98 % was achieved. • MnFe 2 O 4 /TiO 2 displayed excellent photodegradation until three cycles.