Catalytic Degradation of Methylene Blue on Magnesium Ferrite Doped with Lanthanides

The development of novel materials and technologies for wastewater treatment from organic pollutants is an urgent task. Nanostructured metal ferrites are characterized by high chemical stability, ease of production, and good magnetic properties, and are promising catalytic materials for advanced oxidation processes. In this study, heterogeneous Fenton catalysts based on magnesium ferrite doped with lanthanide ions are synthesized and studied. It is established that the obtained samples are single-phase products with a spinel ferrite structure. It is shown that crystal lattice parameter a ranges from 8.387 to 8.431 angstrom, depending on the nature of the dopant ion, and increases with an increase in the cation radius. The unit cell volume has similar values for the synthesized samples and ranges from about 0.590 to 0.599 nm(3). The doping of magnesium ferrite causes a decrease in the average crystallites size, which ranges from about 12.4 to 19.4 nm for the obtained samples. The catalytic activity of magnesium ferrites in the Fenton and photo-Fenton processes of oxidative degradation of methylene blue is studied. It is shown that the efficiency of oxidative degradation of the dye reaches, regardless of the nature of the dopant ion, 95-100% when the process is carried out under UV and visible radiation in 20 and 60 min, respectively. The initial magnesium ferrite is characterized by the highest catalytic activity when using the visible range of radiation, and magnesium ferrite samples doped with La3+, Ce3+, and Dy3+ ions exhibit the highest catalytic activity under UV radiation. The obtained results are of interest for the direct control of the crystal structure and catalytic properties of heterogeneous Fenton catalysts based on magnesium ferrite doped with lanthanides.