Degradation of malachite green by Sm2O3 microspheres synthesized by the coprecipitation method

Abstract

This work reports the synthesis of samarium oxide (Sm2O3) microspheres and their effectiveness in degrading malachite green (MG) dye, both in the dark and under UV light. Single-phase cubic Sm2O3 (C-type) was prepared by a direct coprecipitation method, followed by calcination at 600 °C, yielding porous spheres with an average diameter of ~2.1 μm, for which an optical bandgap of 4.3 eV was determined. Remarkably, the material exhibited significant MG degradation in darkness within the first 2 h. which was attributed to the property of Sm₂O₃ to generate reactive oxygen species (ROS), such as hydroxyl radicals (•OH) and • $${O}_{2}^{-}$$ ions). Under UV light, the percentage of degradation increased by a very small amount indicating as a key factor the generation of ROS. Although this oxide is expensive, compared to other well-known materials, reuse tests suggest that it is a promising material for water remediation.