The present work introduces a new method for the recycling of waste flocculation sludge to prepare electrode materials for supercapacitor. Hazardous azo dye was removal from textile dying wastewater by a new chitosan-based flocculant, and the generated dye sludge flocs was used as a nitrogen-containing precursor for the fabrication of N-doped carbon materials. The influence of azo dye on specific surface areas, nitrogen content, pore evolution of the resulting products and their electrochemical performance were investigated in detail. The results demonstrated a dual role of azo dye worked as both a nitrogen resource and pore-forming agent. The resulting N-doped carbon nanosheets derived from azo dye flocs demonstrated high electrochemical capacitance and good stability for supercapacitor electrode, which is attributed to the unique nitrogen doping, higher specific surface area and efficient charge transfer ability.

Nitrogen self-doped porous carbon nanosheets derived from azo dye flocs for efficient supercapacitor electrodes
    Abstract
    1 Introduction
    2 Experimental
        2.1 Materials
        2.2 Procedure for manufacturing the carbon nanosheets from azo dye flocs
        2.3 Characterization of materials
        2.4 Electrochemical measurements
    3 Results and discussion
        3.1 Characterization of the resulting annealed product
        3.2 Electrochemical performance of the N-doped carbon nanosheets
    4 Conclusions
    Acknowledgements 
    References

• Tingting Wei(Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University)
• Liang Wu(Chongqing Daxin Pharmaceutical Co. Ltd)
• Feng Yu(Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University)
• Yin Lv(Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University)
• Long Chen(Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University)
• Yulin Shi(Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University)
• Bin Dai(Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University)