Radical-based degradation of sulfamethoxazole via UVA/PMS-assisted photocatalysis, driven by magnetically separable Fe3O4@CeO2@BiOI nanospheres

Abstract

In this work, novel magnetic Fe3O4@CeO2@BiOI nanospheres were synthesized for the heterogeneous photocatalytic activation of peroxymonosulfate (PMS) towards sulfamethoxazole (SMX) degradation. The phase purity, morphology, and surface properties of the nanocomposite were fully characterized and confirmed the formation of a heterojunction between the magnetic Fe3O4@CeO2 and BiOI. Low catalyst (0.1 g/L) and PMS addition (0.2 mM) under UVA-LED light irradiation led to high catalytic activity in SMX degradation (97%, kapp = 0.221 min−1) within 15 min. The highest quantum yield (QY) value (5.02 × 10−4 molecules photon−1) was measured for the ternary Fe3O4@CeO2@BiOI nanocomposite, which is 3.54, 3.76, and 4.04 times higher than Fe3O4@CeO2, BiOI, and CeO2 coupled with PMS/UVA, respectively. Furthermore, different experimental conditions, including initial solution pH, catalyst:PMS ratio, water matrix ions on the Fe3O4@CeO2@BiOI/PMS/UVA system, were investigated under the optimum reaction conditions. As deduced from the LC/MS analysis, the possible SMX degradation pathways were proposed. Based on radicals scavenging experiments, SO4∙-, HO∙, and O2∙- are mainly involved in SMX degradation. Finally, recycling and leaching experiments confirmed a stable material with coherent catalytic performance for the activation of PMS by Fe3O4@CeO2@BiOI catalyst under UVA, with excellent magnetic recovery capabilities. As such, this material has high potential for degradation of organic contaminants and in extension for water treatment processes.