Solution Combustion Synthesis of Environmentally Friendly Magnetic Composites Based on Iron Oxide and Mango (Mangifera Indica L.) waste for UV and Solar - Driven Heterogeneous Photocatalysis

Abstract

Materials based on iron oxide were prepared via closed system solution combustion synthesis (IOP), evaluating the effect of the addition of mango seed Husk (T) peel (C) and mixture of the portions (M) on the material properties obtained (IOT, IOC and IOM, respectively). The structural (XRD, Mössbauer), morphological (SEM and TEM), optical (UV-VIS diffuse reflectance), textural (BET) and magnetic (VSM) properties of the materials obtained were evaluated. Different phase compositions (hematite, magnetite and maghemite) were identified in the structure of the materials. The addition of mango residue favored the formation of magnetite with superparamagnetic particles in the IOC sample. The solids were evaluated in the methylene blue photocatalysis at different concentrations, observing different effects on the discoloration rate: the IOP sample presented a better performance at the lowest concentration (50 mg L-1) of the dye, with 98% discoloration after 90 minutes and a specific speed of 44.7 x 10-3 min-1, which can be explained by the heterojunction effect, which makes electronic recombination harder, increasing the quantum yield of the photocatalyst. At the concentration of 70 mg L-1, the best catalyst was the IOM with 82% of discoloration and specific speed of 15.8 x 10-3 min-1, which can be explained by the increase in the specific area due to the insertion of biomass, which improved adsorptive capacity, maintaining the observed heterojunction effects. Under Sunlight, the best composite was IOC, with 90.5% discoloration and activity of 29.8 x 10-3 min-1, justified by the combination of favorable textural and optical properties.