a b s t r a c t
Cryptomelane type manganese oxide OMS-2 was prepared and tested in heterogeneous activation of
peroxymonosulfate (PMS) for Acid Orange 7 (AO7) degradation in aqueous solutions. X-ray diffraction,
scanning electron microscopy, N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy,
X-ray photoelectron spectroscopy (XPS), and electron spin resonance spectroscopy (ESR) were
used to characterize the properties ofthe material. The effect of several parameters on its catalytic activity
was also investigated. It was found thatthe catalyst was very active for AO7 and other organic dyes degradation,
and presented a long-term stability during multiple runs. Results from XPS and ESR suggested
thatthe highly catalytic efficiency possible involved the activation of PMS to sulfate radicals meditated by
the redox pair of Mn(IV)/Mn(III) in OMS-2. Based on intermediate detections, the degradation pathway
of AO7 in the OMS-2/PMS system was proposed.