Efficient activation of periodate using MnFe₂O₄/BC composite for removal of organic contaminants: Performance and mechanism

The periodate (PI)-based advanced oxidation process (AOP) is an economical and energy-saving method for remediating water by degrading pollutants. An efficient system for PI activation was developed by loading manganese ferrite spinel (MnFe₂O₄) on biochar (BC) through a facile method, affording a metal-oxide MnFe₂O₄/BC composite catalyst. The developed system demonstrated significant effectiveness in eliminating various organic pollutants, particularly achieving high removal (5.26 and 2.83 times that of biochar and MnFe₂O₄, respectively) and mineralization (49.7 %) of the model pollutant tetracycline hydrochloride (TC) within 30 min. The system exhibited outstanding catalytic performance under various environmental conditions (pH, inorganic salts, humic acid, and real water bodies), as evidenced by quenching experiments and electron paramagnetic resonance (EPR) studies, proving that superoxide radicals (O₂^•-) are the main reactive species for TC degradation in the reaction system, in addition to singlet oxygen (¹O₂), iodyl radicals (IO₃^•) and hydroxyl radicals (•OH). Potential pathways for TC degradation in this system were revealed based on density functional theory (DFT) and the ecological toxicity of the intermediates was analyzed through quantitative structure–activity relationship (QSAR) assessment. Analysis of the magnetic hysteresis and cycling stability demonstrated that the composites were stable and could be recycled by applying a magnetic field. This work opens a new pathway for designing efficient PI activators for the selective oxidation of organic pollutants and highlights the potential application of this system in practical wastewater treatment. © 2024 Elsevier B.V.