Highly-efficient and stable MgCo2O4 spinel for bisphenol a removal by activating peroxymonosulfate via radical and non-radical pathways

Abstract

• Peroxymonosulfate can be activated by MgCo 2 O 4 over a board pH range of 5 to 9. • Mg 2+ facilitates the redox cycle of Co 2+ / Co 3+ on the surface of MgCo 2 O 4. • MgCo 2 O 4 /PMS system can degrade 99.6% BPA efficiently within 10 min. • Electron-transfer reactions rather than 1 O 2 dominated the non-radical pathway. • MgCo 2 O 4 is a highly-efficient and stable activator for PMS. Nowadays, the limited catalytic efficiency, secondary pollution of metal leaching and stability decrease during reuse bring challenges to practical application of heterogeneous catalysts in sulfate radical-based advanced oxidation processes. Herein, MgCo 2 O 4 spinel was synthesized through hydrothermal method and tested for its catalytic performance of activating PMS by using bisphenol A (BPA) as the target pollutant. MgCo 2 O 4 /PMS system can degrade 99.6% BPA efficiently at pH 7.2 within 10 min. The morphological and physicochemical properties of MgCo 2 O 4 were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Unlike conventional PMS activation, radical and non-radical pathways were identified through utilizing X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and radical quenching experiments. Tetrahedral Mg 2+ might make MgCo 2 O 4 more stable and promote the Co 2+ /Co 3+ redox, which dominated the catalytic ability of MgCo 2 O 4 . MgCo 2 O 4 spinel is efficient, stable, low-cost, and simple to synthesize, leading to BPA degradation via both radical and non-radical pathways. This research would extend the mechanism and potential application of spinel catalysis in water treatment.