Catalytic decolorization of methyl orange by the rectorite–sulfite system

•Methyl orange can be efficiently decolorized by the simple rectorite-sulfite system.•The rectorite was stable during the dye decolorization.•The possible catalytic mechanism was discussed.

The simple rectorite–sulfite system has been found to decolorize methyl orange efficiently with dioxygen as the oxidant under mild conditions. The rectorite was also stable during the reaction without significant metal ions leaching. The iron impurity, mainly presented as highly dispersed hematite, probably acted as the active centers. Suggested by the electron spin resonance spin-trapping technologies and radical scavenger measurements, the produced sulfate radicals were to be responsible for the dye decolorization. This study can provide us a simple, effective and economic system ideal for the treatment of toxic and nonbiodegradable azo dye.

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