Visible-light-driven activation of sodium persulfate for accelerating orange II degradation using ZnMn2O4 photocatalyst

A special catalytic system was obtained by using ZnMn 2 O 4 (ZMO) materials to activate Na 2 S 2 O 8 and catalytically degrade organic dye orange II under visible light irradiation. The ZMO nanoparticles were prepared by a simple one-step method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). In this study, the ZMO/Na 2 S 2 O 8 system was used to degrade orange II, and the degradation rate reached 97.44% in 60 min. ZMO catalysts could be recycled for at least five times, and its degradation rate was only decreased by 1.84%. The free radicals produced during the degradation of orange II were studied by classical quenching experiments, and the different types of free radicals produced in the system were further confirmed by electron paramagnetic resonance (EPR) spectroscopy. The catalytic degradation of orange II in this system was mainly caused by the production of superoxide , sulfate and hydroxyl radicals, which achieved high degradation.