Accelerated decomposition of Oxone using graphene-like carbon nitride with visible light irradiation for enhanced decolorization in water

• GCN was used to accelerate the Oxone decomposition under visible light irradiation.
• The accelerated Oxone decomposition generated sulfate radicals to decolorize dye.
• Effects of GCN loading, Oxone dosage, pH and co-existing compounds were examined.
• Oxone decomposition by Oxone-GCN/vis was validated by EPR spectroscopy.
• GCN can be recyclable to accelerate the Oxone decomposition for the decolorization.

Degradation of organic pollutants using Oxone decomposition has been investigated to address aqueous pollution. Although metallic catalysts can effectively accelerate the Oxone decomposition, using non-metal catalysts to accelerate the Oxone decomposition attract great attention because it minimizes usage of metals and environmental concerns. In this study, graphene-like carbon nitride (GCN) is proposed as a non-metal catalyst to accelerate the Oxone decomposition. Under visible light irradiation (vis), photocatalytic reaction of GCN can initiate the Oxone decomposition to generate sulfate radicals for decolorization in water. A higher GCN loading appeared to enhance the decolorization but over loading could block the light irradiation. The elevated temperature was preferable to this Oxone-GCN/vis process, whereas the alkaline condition was adverse. Despite a high concentration of NaCl in the solution, the decolorization using Oxone-GCN/vis was not noticeably hindered, while ascorbic acid and ethanol could significantly inhibit the Oxone decomposition. Electron paramagnetic resonance spectroscopic results also validated that the combination of GCN/vis successfully accelerated the Oxone decomposition. A multiple-cycle test of using GCN/vis to facilitate the Oxone decomposition was also demonstrated without regeneration treatments on the spent GCN, showing that GCN/vis can be an effective and recyclable catalytic system to decompose Oxone to decolorize dyes in water.

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