Periodate activation with stable MgMn₂O₄ spinel for bisphenol A removal: Radical and non-radical pathways

Nowadays, the limited catalytic efficiency, metal leaching, and stability decrease during catalyst reuse hinder the heterogeneous catalysis application in water treatment. Moreover, the heterogeneous catalysis mechanism regarding novel sodium periodate (NaIO₄)-based advanced oxidation process (AOP) is ambiguous. Herein, MgMn₂O₄ spinel was synthesized through the co-precipitation method to test the NaIO₄-based AOP's mechanism. The morphological and physicochemical properties of MgMn₂O₄ were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). In this research, 0.1 g L⁻¹ MgMn₂O₄ activated 1 mM NaIO₄ to remove 10 μM bisphenol A (BPA) in 60 min without toxic iodine species generation and the acute toxicity decrease through radical (iodine active substances, IO₃^•) and non-radical (¹O₂, Manganese (IV)-oxo species) pathways by utilizing X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), radical quenching experiments, and methyl phenyl sulfoxide (PMSO)-based probing experiment. With tetrahedral Mg²⁺ introduction and the Mn²⁺ /Mn³⁺ /Mn⁴⁺ redox domination, the MgMn₂O₄ shows high catalytic ability for NaIO₄. To summarize, this research would extend the mechanism for the NaIO₄-based advanced oxidation process.