A novel quinone/reduced graphene oxide composite as a solid-phase redox mediator for chemical and biological Acid Yellow 36 reduction

Abstract

A novel quinone-modified graphene material was developed to enhance the catalytic performance of graphene for the transformation of environmental pollutants. Graphene oxide (GO) was first reduced with diethylenetriamine and the obtained NH₂-RGO was further covalently modified with anthraquinone-2-sulfonic acid (AQS). The prepared AQS-modified RGO (AQS-RGO) was characterized by XPS, IR and SEM, respectively. The catalytic performance of AQS-RGO was investigated during azo dye Acid Yellow 36 (AY 36) decolorization. It was shown that pH and temperature had significant effects on AY 36 chemical decolorization by Na₂S. At the pH of 6.0, AQS-RGO exhibited better catalytic performance compared with NH₂-RGO due to the lower activation energy of the AQS-RGO amended system. AY 36 bio-decolorization could be enhanced in a dose-dependent manner with AQS-RGO. In the presence of 25 mg L⁻¹ AQS-RGO, the AY 36 bio-decolorization rate was 6.7-fold higher than that mediated by NH₂-RGO, indicating that AQS-RGO is a better electron-transfer mediator. Based on the above results, the electron transfer pathways of AQS-RGO-mediated AY 36 decolorization were proposed. These findings indicate that the application of AQS-RGO is a feasible method to enhance the treatment of azo dye-containing wastewater.